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MapK
MapK MapK(10)
ERK is sometimes used as a synonym for MAPK, but has been adopted for a specific subset of the mammalian MAPK family. ERKs or classical MapKs are kinase signalling proteins involved regulation of meiosis, mitosis, and post-mitotic functions in differentiated cells. The Raf/Mek/Erk signal transduction pathway regulates proliferation, differentiation, survival, senescence, and migration.(5) In the MAPK/ERK pathway, Ras activates c-Raf, followed by mitogen-activated protein kinase kinase (called MKK, MEK, or MAP2K) and then MAPK1/2.(1) ERK phosphorylates a number of substrates with critical roles in regulating gene expression, proliferation, and cell survival.(6) Many different stimuli, including growth factors, cytokines, virus infection, ligands for heterotrimeric GPCR, transforming agents, and carcinogens, activate the ERK pathway.(2,3,4)
P38s are a class of mitogen-activated protein kinases that are responsive to stress stimuli, such as cytokines, ultraviolet irradiation, heat shock, and osmotic shock, and are involved in cell differentiation, apoptosis, and autophagy.(7) There are four p38 MAP kinases, MAPK14, MAPK11, MAPK12/ERK6, and MAPK13/SAPK4.(7) MKK3 and SEK activate p38 MAP kinase by phosphorylation. Activated p38 MAP kinase phosphorylates MAPK AP kinase 2, the transcription factors ATF2, Mac and MEF2, and post-transcriptional regulating factors like TTP.(7, 8)
Disruption of the ERK pathway is common in cancers, especially Ras, c-Raf, and receptors such as HER2.(1) Some components of these pathways are mutated or aberrantly expressed in human cancer (e.g., Ras, B-Raf). Mutations also occur at genes encoding upstream receptors (e.g., EGFR and Flt-3) and chimeric chromosomal translocations (e.g., BCR-ABL) which transmit their signals through these cascades.(2, 3) Because the development of RAS inhibitors have been largely unsuccessful for lung cancer (e.g., farnesyltransferase inhibitors), various investigations thus have focused on the modulation of downstream proteins or protein trafficking pathways. The Ras/Raf/MEK/ERK and PI3K/PTEN/Akt/mTOR cascades are often activated by genetic alterations in upstream signaling molecules such as RTK. Targeting these pathways is often complex and can result in pathway activation depending on the presence of upstream mutations (e.g., Raf inhibitors induce Raf activation in cells with wild type RAF in the presence of mutant, activated RAS) and rapamycin can induce Akt activation. Targeting with inhibitors directed at two constituents of the same pathway or two different signaling pathways may be a more effective approach.(9)
Growth factors and mitogens use the Ras/Raf/MEK/ERK signaling cascade to transmit signals from their receptors to regulate gene expression and prevent apoptosis.(2, 3) The Raf/Mek/Erk signal transduction pathway regulates proliferation, differentiation, survival, senescence, and migration.(5)
MEK enzymes selectively phosphorylate serine/threonine and tyrosine residues within the activation loop of their specific MAP kinase substrates.(10, 11) MEK1 and MEK2 are the prototype members of MEK family proteins.(10) MEK 1/2 proteins consist of a N-terminal sequence, a protein kinase domain, and a C-terminal sequence. The N-terminal sequence contains an inhibitory/allosteric segment, a nuclear export sequence (a unique feature not shared with other MAPKK family members), and a docking site (D-domain) that aids in binding ERK substrates.(10)
MEK inhibitors can induce significant tumor regressions in KRAS - or BRAF-induced lung tumors.(12) Unlike Raf inhibitors, Mek inhibitors are unfortunately rather toxic for normal tissues.(5) MEK inhibitors differ from most other kinase inhibitors as they do not compete with ATP binding (non-ATP competitive), which confers a high specificity. Most MEK inhibitors are specific and do not inhibit many different protein kinases. Effective targeting of MEK1/MEK2 is highly specific, as ERK1/ERK2 are the only well-described downstream targets. A distinct advantage of inhibiting MEK is that it can be targeted without knowledge of the precise genetic mutation that results in its aberrant activation.(9) This is not true with targeting Raf as certain Raf inhibitors will activate Raf and also certain B-Raf-specific inhibitors will not be effective in the presence of RAS mutations. An advantage of targeting MEK is that the Ras/Raf/MEK/ERK pathway is a convergence point where a number of upstream signaling pathways can be blocked with the inhibition of MEK.(9)

Drugs/Indications
Marketed Drugs
Generic Code Old Code Brand Company Indication trials
trametinib GSK1120212 Mekinist GSK Mkt: melanoma; P2: NSCLC, CRC, MM, oral, cervical, solid; P1: HCC, rectal trials
Trial Drugs/Indications
Generic Code Old Code Brand Company Indication trials
binimetinib MEK162 MSC1936369B, ARRY-438162, ARRY-162 Array P3: ovarian, melanoma; P2: CRC, solid, hem; P1/2: leukemia, glioma, GIST, pancreatic, AML; P1: NSCLC, biliary, MDS trials
selumetinib AZD6244 ARRY-142886 AstraZeneca P3: NSCLC, thyroid, melanoma; P2: solid, CRC (terminated), HCC (terminated), BC, ovarian, fallopian, gastric, esophageal, pancreatic, endometrial, gallbladder (terminated), RCC, glioma (withdrawn), nasal, B-cell lymphoma, biliary, trials
PD-0325901 Pfizer P3: BC; P2: NSCLC, HCC, ovarian, PC, GBM, GIST, solid, CRC, liposarcoma, urothelial; P1/w: melanoma, AML, ALL trials
pimasertib MSC1936369B SAR405838, AS703026, SNX-1012 Sanofi P2: ovarian, pancreatic, melanoma; P1: solid trials
antroquinonol CHEBI:65415 Hocena Gold P2: NSCLC trials
cobimetnib GDC-0973 RG7421, XL518 Roche P2: melanoma, BC; P1: pancreatic, endometrial, solid, CRC, gastric trials
AZD2644 AstraZeneca P2: melanoma trials
refametinib BAY 86-9766 AR 119, RDEA 119 Bayer P2: HCC, biliary; P1/2: pancreatic, solid trials
LY2228820 Eli Lilly P2: GBM, ovarian, fallopian; P1: solid trials
BVD-523 BioMed Valley P1/2: solid, MDS trials
WX-554 Wilex P1/2: solid trials
E6201 Eisai P1/2: AML, MDS, CMML; P1: solid trials
LY3007113 Eli Lilly P1: various trials
BI 847325 Boehringer Ingelheim P1: solid trials
CKI27 RG7304, RO5126766 Chugai P1: solid trials
RO4987655 RG7167, CH4987655 Roche P1: solid trials
GDC-0994 Roche P1: solid trials
MK-8353 SCH 900353 Merck P1: solid trials
MSC2015103B AS703988 EMD Serono P1: solid trials
TAK-733 Takeda P1: solid trials
ARRY-614 Array P1: MDS trials
Failed Drugs
Generic Code Old Code Brand Company Indication trials
SCIO-469 Tocris Last new trial started in 2005; P2: MM, MDS, hem, bone trials
MRPL28 Tocris Last new trial started in 2005; P1/2: melanoma trials
TAK-960 Takeda terminated; P1: solid trials
AZD8330 ARRY-704 AstraZeneca terminated; solid trials
News
References

1. Extracellular_signal-regulated_kinases. Available from: http://en.wikipedia.org/wiki/Extracellular_signal-regulated_kinases.

2. McCubrey JA SL, Chappell WH, Abrams SL, Wong EW, Chang F, Lehmann B, Terrian DM, Milella M, Tafuri A, Stivala F, Libra M, Basecke J, Evangelisti C, Martelli AM, Franklin RA. Roles of the Raf/MEK/ERK pathway in cell growth, malignant transformation and drug resistance. Biochim Biophys Acta. 2007;1773(8):1263-84; PMCID: 17126425.

3. Stirewalt DL KK, Meshinchi S, Appelbaum FR, Slovak ML, Willman CL, Radich JP. FLT3, RAS, and TP53 mutations in elderly patients with acute myeloid leukemia. Blood. 2001;97:3589-95.

4. Vogelstein B, Kinzler KW. Cancer genes and the pathways they control. Nature medicine. 2004;10(8):789-99.

5. Cseh B, Doma E, Baccarini M. The "RAF" neighborhood: Protein-protein interaction in the Raf/Mek/Erk pathway. FEBS letters. 2014.

6. Corcoran RB SJ, Engelman JA. Potential therapeutic strategies to overcome acquired resistance to BRAF or MEK inhibitors in BRAF mutant cancers. Oncotarget. 2011;4:336-46; PMCID: 21505228.

7. Cortez V NB, Chakravarty D, Vadlamudi RK. Integrin-linked kinase 1: role in hormonal cancer progression. Front Biosci (Schol Ed). 2010;3:788-96; PMCID: 21196412.

8. Tudor C, Marchese FP, Hitti E, Aubareda A, Rawlinson L, Gaestel M, Blackshear PJ, Clark AR, Saklatvala J, Dean JL. The p38 MAPK pathway inhibits tristetraprolin-directed decay of interleukin-10 and pro-inflammatory mediator mRNAs in murine macrophages. FEBS letters. 2009;583(12):1933-8.

9. McCubrey JA, Steelman LS, Chappell WH, Abrams SL, Franklin RA, Montalto G, Cervello M, Libra M, Candido S, Malaponte G. Ras/Raf/MEK/ERK and PI3K/PTEN/Akt/mTOR cascade inhibitors: how mutations can result in therapy resistance and how to overcome resistance. Oncotarget. 2012;3(10):1068.

10. Akinleye A, Furqan M, Mukhi N, Ravella P, Liu D. MEK and the inhibitors: from bench to bedside. J Hematol Oncol. 2013;6(1):27.

11. Chang L, Karin M. Mammalian MAP kinase signalling cascades. Nature. 2001;410(6824):37-40.

12. T Reungwetwattana GD. Targeted therapies in development for non-small cell lung cancer. J Carcinog. 2013;12:22; PMCID: PMC3927069.

13. Erk_cascade_2. Available from: http://dna.brc.riken.jp/en/GENESETBANK/0200104Erk_cascade_2.html.



News
Friday, September 16, 2016 4:27 PM|Gang Ma, Jianjun He, Yang Yu, Yixiang Xu, Xiaobin Yu, Jarrod Martinez, David M. Lonard, Jianming Xu|International Journal of Biological Sciences|Labels: MapK, breast cancer

Twist1 is a transcription factor driving epithelial-mesenchymal transition, invasion and metastasis of breast cancer cells. Mice with germ-line Twist1 knockout are embryonic lethal, while adult mice with inducible Twist1 knockout have no obvious health problems, suggesting that Twist1 is a viable therapeutic target for the inhibition of invasion and metastasis of breast cancer in adult patients. In this study, we expressed a luciferase protein or a Twist1-luciferase fusion protein in HeLa cells as part of a high throughput system to screen 1280 compounds in the Library of Pharmacologically Active Compounds (LOPAC) from Sigma-Aldrich for their effects on Twist1 protein expression. One of the most interesting compounds identified is tamoxifen, a selective estrogen receptor (ER) modulator used to treat ER-positive breast cancer. Tamoxifen treatment significantly accelerated Twist1 degradation in multiple cell lines including HEK293 human kidney cells, 4T1 and 168FARN mouse mammary tumor cells with either ectopically or endogenously expressed Twist1. Tamoxifen-induced Twist1 degradation could be blocked by the MG132 proteasome inhibitor, suggesting that tamoxifen induces Twist1 degradation through the ubiquitination-proteasome pathway. However, tamoxifen-induced Twist1 degradation was independent of Twist1 mRNA expression, estrogen signaling and MAPK-mediated Twist1 phosphorylation in these cells. Importantly, tamoxifen also significantly inhibited invasive behavior in Matrigel and lung metastasis in SCID-bg mice of ER-negative 4T1 mammary tumor cells, which depend on endogenous Twist1 to invade and metastasize. These results indicate that tamoxifen can significantly accelerate Twist1 degradation to suppress cancer cell invasion and metastasis, suggesting that tamoxifen can be used not only to treat ER-positive breast cancers but also to reduce Twist1-mediated invasion and metastasis in ER-negative breast cancers.

Friday, September 16, 2016 4:27 PM|Pengfei Ma, Yujie Fu, Minjiang Chen, Ying Jing, Jie Wu, Ke Li, Ying Shen, Jian-Xin Gao, Mengzhao Wang, Xiaojing Zhao, Guanglei Zhuang|Theranostics|Labels: EGFR, MapK

Both adaptive and acquired resistance significantly limits the efficacy of the epidermal growth factor receptor (EGFR) kinase inhibitors. However, the distinct or common mechanisms of adaptive and acquired resistance have not been fully characterized. Here, through systematic modeling of erlotinib resistance in lung cancer, we found that feedback reactivation of MAPK signaling following erlotinib treatment, which was dependent on the MET receptor, contributed to the adaptive resistance of EGFR inhibitors. Interestingly, acquired resistance to erlotinib was also associated with the MAPK pathway activation as a result of CRAF or NRAS amplification. Consequently, combined inhibition of EGFR and MAPK impeded the development of both adaptive and acquired resistance. These observations demonstrate that adaptive and acquired resistance to EGFR inhibitors can converge on the same pathway and credential cotargeting EGFR and MAPK as a promising therapeutic approach in EGFR mutant tumors.

Thursday, September 15, 2016 7:42 AM|L. G. T.|JournalTOCs API - Clinical Cancer Research (27 articles)|Labels: MapK, salivary duct cancer

Molecular Characterization of Salivary Duct Carcinoma
Dalin, M. G Desrichard, A, Katabi, N, Makarov, V, Walsh, L. A, Lee, K.-W, Wang, Q, Armenia, J, West, L, Dogan, S, Wang, L, Ramaswami, D, Ho, A. L, Ganly, I, Solit, D. B, Berger, M. F, Schultz, N. D, Reis-Filho, J. S, Chan, T. A, Morris, L. G. T.
Clinical Cancer Research, Vol. 22, No. 18 (2016) pp. 4623 - 4633
Purpose: Salivary duct carcinoma (SDC) is an aggressive salivary malignancy, which is resistant to chemotherapy and has high mortality rates. We investigated the molecular landscape of SDC, focusing on genetic alterations and gene expression profiles. Experimental Design: We performed whole-exome sequencing, RNA sequencing, and immunohistochemical analyses in 16 SDC tumors and examined selected alterations via targeted sequencing of 410 genes in a second cohort of 15 SDCs. Results: SDCs harbored a higher mutational burden than many other salivary carcinomas (1.7 mutations/Mb). The most frequent genetic alterations were mutations in TP53 (55%), HRAS (23%), PIK3CA (23%), and amplification of ERBB2 (35%). Most (74%) tumors had alterations in either MAPK (BRAF/HRAS/NF1) genes or ERBB2. Potentially targetable alterations based on supportive clinical evidence were present in 61% of tumors. Androgen receptor (AR) was overexpressed in 75%; several potential resistance mechanisms to androgen deprivation therapy (ADT) were identified, including the AR-V7 splice variant (present in 50%, often at low ratios compared with full-length AR) and FOXA1 mutations (10%). Consensus clustering and pathway analyses in transcriptome data revealed striking similarities between SDC and molecular apocrine breast cancer. Conclusions: This study illuminates the landscape of genetic alterations and gene expression programs in SDC, identifying numerous molecular targets and potential determinants of response to AR antagonism. This has relevance for emerging clinical studies of ADT and other targeted therapies in SDC. The similarities between SDC and apocrine breast cancer indicate that clinical data in breast cancer may generate useful hypotheses for SDC. Clin Cancer Res; 22(18); 4623–33. ©2016 AACR.

Tuesday, September 13, 2016 11:38 PM|Johanna Samulin Erdem, Vidar Skaug, Aage Haugen, Shanbeh Zienolddiny|Journal of Cancer|Labels: MapK, lung cancer

Identification of genetic alterations in members of the p38 mitogen-activated protein kinase (MAPK) pathway is important as these proteins have dynamic roles in tumor progression and may serve as potential therapeutic targets in cancer. We analyzed tumor and non-tumorous lung tissue of 233 non-small cell lung cancer (NSCLC) patients for the presence of copy number alterations (CNAs) in the MAPK kinase 3 (MKK3) and MAPK-activated kinase 2 (MK2) genes. We report frequent CNAs in MKK3 and MK2 genes in NSCLC. Copy number losses were detected in 31% of NSCLC tumors (odds ratio: 7.08, 95% confidence interval: 3.2-15.6, P<0.001) for the MKK3 gene and in 28% of tumors for the MK2 gene (odds ratio: 3.68, 95% confidence interval: 1.9-7.2, P<0.001). Several of the non-tumorous tissues showed an elevated MKK3 copy number, with a concurrent loss of this in 89% of the paired tumors. MKK3 gene deletions were significantly more frequent in squamous and large cell carcinoma than in adenocarcinoma. These data demonstrate a novel loss of MKK3 and MK2 genomic copy numbers in NSCLC tumors, and suggest these genes as interesting therapeutic candidates in NSCLC.

Tuesday, September 13, 2016 8:19 PM|Andrea L. George, Robert Suriano, Shilpi Rajoria, Maria C. Osso, Neha Tuli, Elyse Hanly, Jan Geliebter, Angelo N. Arnold, Marc Wallack, Raj K. Tiwari|Journal of Cancer (RSS 2.0)|Labels: BRAF, MapK, melanoma

Over expression of various immunogenic melanoma associated antigens (MAAs) has been exploited in the development of immunotherapeutic melanoma vaccines. Expression of MAAs such as MART-1 and gp100 is modulated by the MAPK signaling pathway, which is often deregulated in melanoma. The protein BRAF, a member of the MAPK pathway, is mutated in over 60% of melanomas providing an opportunity for the identification and approval by the FDA of a small molecule MAPK signaling inhibitor PLX4032 that functions to inactivate mutant BRAFV600E.

To this end, we characterized five patient derived primary melanoma cell lines with respect to treatment with PLX4032. Cells were treated with 5μM PLX4032 and harvested. Western blotting analysis, RT-PCR and in vitro transwell migration and invasion assays were utilized to determine treatment effects. PLX4032 treatment modulated phosphorylation of signaling proteins belonging to the MAPK pathway including BRAF, MEK, and ERK and abrogated cell phenotypic characteristics such as migration and invasion. Most significantly, PLX4032 led to an up regulation of many MAA proteins in three of the four BRAF mutated cell lines, as determined at the protein and RNA level. Interestingly, MAGE-A1 protein and mRNA levels were reduced upon PLX4032 treatment in two of the primary lines.

Taken together, our findings suggest that the BRAFV600E inhibitor PLX4032 has therapeutic potential over and above its known target and in combination with specific melanoma targeting vaccine strategies may have further clinical utility.

Sunday, September 11, 2016 11:00 PM|Qi, Kang; Li, Yang; Li, XueBing; Lei, Xing; Wang, Bo; Zhang, LianBin; Chu, XiangYang|Anti-Cancer Drugs - Published Ahead-of-Print|Labels: MapK, lung cancer
Inhibitor of differentiation 4 (Id4) plays an important role in tumorigenesis, but its role in cancer chemoresistance remains unclear. Our study showed that Id4 expression in cisplatin-resistant A549/DDP cells was higher than that in parental A549 cells. Moreover, overexpression of Id4 in A549 cells results in cisplatin resistance and apoptosis inhibition, while increasing the IC50 for cisplatin through activation of phospho-p38 MAPK. However, Id4 knockdown in A549/DDP cells was shown to resensitize A549/DDP cells to cisplatin and induce apoptosis, as well as decrease the IC50 for cisplatin through inactivation of phospho-p38 MAPK. In addition, a p38 MAPK inhibitor (SB202190) could partly reverse both Id4-reduced apoptosis and Id4-induced cisplatin resistance. These results suggest that Id4 inhibits cisplatin-induced apoptosis in human lung adenocarcinoma, partially through activation of the p38 MAPK pathway. Our research indicates that Id4 may be a new target for non-small-cell lung cancer treatment. Copyright (C) 2016 Wolters Kluwer Health, Inc. All rights reserved.
Friday, September 2, 2016 1:30 AM|Junya Azumi, Toshiaki Tsubota, Tomohiko Sakabe, Goshi Shiota|Cancer Science|Labels: MapK, liver cancer
Sorafenib, a multi-kinase inhibitor, is the only standard clinical drug for patients with advanced hepatocellular carcinoma (HCC); however, development of sorafenib resistance in HCC often prevents its long-term efficacy. Therefore, novel targets and strategies are urgently needed to improve the antitumor effect of sorafenib. In the present study, we examined the novel mechanisms of sorafenib resistance of HCC cells by investigating the difference in sorafenib sensitivity between two HCC cell lines. Sorafenib induced more apoptosis of HepG2 cells compared to Hep3B cells. Sorafenib exposure to HepG2 cells but not Hep3B cells increased the expression of proapoptotic factor PUMA, and activated PARP and caspase-3. Notably, microRNA-181a (miR-181a) expression levels were lower in HepG2 cells than in Hep3B cells. Exogenous miR-181a expression in HepG2 cells reduced apoptosis, whereas inhibition of miR-181a in Hpe3B cells increased apoptosis. In addition, we demonstrated that miR-181a directly targets RASSF1, a MAPK signaling factor, and knockdown of RASSF1 increased sorafenib resistance. Taken together, these results suggest that miR-181a provokes sorafenib resistance through suppression of RASSF1. Our data provide important insight into the novel therapeutic strategy against sorafenib resistance of HCC cells by targeting of miR-181a pathway. Sorafenib, a multi-kinase inhibitor, is the first systemic drug against patients with advanced hepatocellular carcinoma (HCC), however, development of sorafenib resistance in HCC often prevents its long-term efficacy. We demonstrate that miR-181a, an onco-microRNA, provokes sorafenib resistance by suppression of tumor suppressor gene RASSF1.
Sunday, August 14, 2016 10:05 PM|Bachegowda, L., Morrone, K., Winski, S. L., Mantzaris, I., Bartenstein, M., Ramachandra, N., Giricz, O., Sukrithan, V., Nwankwo, G., Shahnaz, S., Bhagat, T. D., Bhattacharyya, S., Assal, A., Shastri, A., Gordon-Mitchell, S., Pellagatti, A., Boultwood, J., Schinke, C., Yu, Y., Guha, C., Rizzi, J., Garrus, J., Brown, S., Wollenberg, L., Hogeland, G., Wright, D., Munson, M., Rodriguez, M., Gross, S., Chantry, D., Zou, Y., Platanias, L. C., Burgess, L. E., Pradhan, K., Steidl, U., Verma, A.|Cancer Research recent issues|Labels: ANG, MapK, AML
Myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) suppress normal hematopoietic activity in part by enabling a pathogenic inflammatory milieu in the bone marrow. In this report, we show that elevation of angiopoietin-1 in myelodysplastic CD34+ stem-like cells is associated with higher risk disease and reduced overall survival in MDS and AML patients. Increased angiopoietin-1 expression was associated with a transcriptomic signature similar to known MDS/AML stem-like cell profiles. In seeking a small-molecule inhibitor of this pathway, we discovered and validated pexmetinib (ARRY-614), an inhibitor of the angiopoietin-1 receptor Tie-2, which was also found to inhibit the proinflammatory kinase p38 MAPK (which is overactivated in MDS). Pexmetinib inhibited leukemic proliferation, prevented activation of downstream effector kinases, and abrogated the effects of TNFα on healthy hematopoietic stem cells. Notably, treatment of primary MDS specimens with this compound stimulated hematopoiesis. Our results provide preclinical proof of concept for pexmetinib as a Tie-2/p38 MAPK dual inhibitor applicable to the treatment of MDS/AML. Cancer Res; 76(16); 4841–9. ©2016 AACR.
Sunday, August 14, 2016 10:05 PM|Menard, J. A., Christianson, H. C., Kucharzewska, P., Bourseau–Guilmain, E., Svensson, K. J., Lindqvist, E., Chandran, V. I., Kȷellen, L., Welinder, C., Bengzon, J., Johansson, M. C., Belting, M.|Cancer Research recent issues|Labels: ERK, MapK
Hypoxia and acidosis are inherent stress factors of the tumor microenvironment and have been linked to increased tumor aggressiveness and treatment resistance. Molecules involved in the adaptive mechanisms that drive stress-induced disease progression constitute interesting candidates of therapeutic intervention. Here, we provide evidence of a novel role of heparan sulfate proteoglycans (HSPG) in the adaptive response of tumor cells to hypoxia and acidosis through increased internalization of lipoproteins, resulting in a lipid-storing phenotype and enhanced tumor-forming capacity. Patient glioblastoma tumors and cells under hypoxic and acidic stress acquired a lipid droplet (LD)-loaded phenotype, and showed an increased recruitment of all major lipoproteins, HDL, LDL, and VLDL. Stress-induced LD accumulation was associated with increased spheroid-forming capacity during reoxygenation in vitro and lung metastatic potential in vivo. On a mechanistic level, we found no apparent effect of hypoxia on HSPGs, whereas lipoprotein receptors (VLDLR and SR-B1) were transiently upregulated by hypoxia. Importantly, however, using pharmacologic and genetic approaches, we show that stress-mediated lipoprotein uptake is highly dependent on intact HSPG expression. The functional relevance of HSPG in the context of tumor cell stress was evidenced by HSPG-dependent lipoprotein cell signaling activation through the ERK/MAPK pathway and by reversal of the LD-loaded phenotype by targeting of HSPGs. We conclude that HSPGs may have an important role in the adaptive response to major stress factors of the tumor microenvironment, with functional consequences on tumor cell signaling and metastatic potential. Cancer Res; 76(16); 4828–40. ©2016 AACR.
Monday, August 1, 2016 10:05 PM|Pearson, A., Smyth, E., Babina, I. S., Herrera-Abreu, M. T., Tarazona, N., Peckitt, C., Kilgour, E., Smith, N. R., Geh, C., Rooney, C., Cutts, R., Campbell, J., Ning, J., Fenwick, K., Swain, A., Brown, G., Chua, S., Thomas, A., Johnston, S. R. D., Ajaz, M., Sumpter, K., Gillbanks, A., Watkins, D., Chau, I., Popat, S., Cunningham, D., Turner, N. C.|Cancer Discovery recent issues|Labels: FGFR, MapK

FGFR1 and FGFR2 are amplified in many tumor types, yet what determines response to FGFR inhibition in amplified cancers is unknown. In a translational clinical trial, we show that gastric cancers with high-level clonal FGFR2 amplification have a high response rate to the selective FGFR inhibitor AZD4547, whereas cancers with subclonal or low-level amplification did not respond. Using cell lines and patient-derived xenograft models, we show that high-level FGFR2 amplification initiates a distinct oncogene addiction phenotype, characterized by FGFR2-mediated transactivation of alternative receptor kinases, bringing PI3K/mTOR signaling under FGFR control. Signaling in low-level FGFR1-amplified cancers is more restricted to MAPK signaling, limiting sensitivity to FGFR inhibition. Finally, we show that circulating tumor DNA screening can identify high-level clonally amplified cancers. Our data provide a mechanistic understanding of the distinct pattern of oncogene addiction seen in highly amplified cancers and demonstrate the importance of clonality in predicting response to targeted therapy.

Significance: Robust single-agent response to FGFR inhibition is seen only in high-level FGFR-amplified cancers, with copy-number level dictating response to FGFR inhibition in vitro, in vivo, and in the clinic. High-level amplification of FGFR2 is relatively rare in gastric and breast cancers, and we show that screening for amplification in circulating tumor DNA may present a viable strategy to screen patients. Cancer Discov; 6(8); 838–51. ©2016 AACR.

This article is highlighted in the In This Issue feature, p. 803

Thursday, July 28, 2016 6:00 PM|Gopal C. Kundu|JournalTOCs API - Journal of Investigative Dermatology (875 articles)|Labels: MapK, Notch, melanoma

Notch1-MAPK Signaling Axis Regulates CD133+ Cancer Stem Cell-Mediated Melanoma Growth and Angiogenesis
Dhiraj Kumar Santosh Kumar, Mahadeo Gorain, Deepti Tomar, Harshal S. Patil, N.N.V. Radharani, T.V.S. Kumar, Tushar V. Patil, H.V. Thulasiram, Gopal C. Kundu
Journal of Investigative Dermatology, Vol. , No. (2016) pp. -
Functional characterization and understanding of the intricate signaling mechanisms in stem like cells is crucial for the development of effective therapies in melanoma. We have studied whether melanoma cells are phenotypically distinct and hierarchically organized according to their tumorigenic nature. We report that melanoma-specific CD133+ cancer stem cells exhibit increased tumor-initiating potential, tumor-endothelial cell interaction and lung metastasis. These cells are able to trans-differentiate into an endothelial-like phenotype when cultured under endothelial differentiation-promoting conditions.

Thursday, July 28, 2016 7:56 AM|Soukup, K., Halfmann, A., Poyer, F., Martin, K., Blauensteiner, B., Huber, B., Kuttke, M., Schabbauer, G., Zopf, L., Zinnanti, J., Dohnal, A. M.|Cancer Research recent issues|Labels: MapK, TNF
The MAPK signaling pathway represents a central player in inflammatory processes. As a downstream target of p38, MAPK-activated protein kinase 2 (MK2) contributes to signal transduction regulating the expression and translation of various targets, among them several cytokines such as tumor necrosis factor (TNF) α. While MK2 was shown to promote an inflammatory macrophage phenotype, we have reported its Th1-attenuating function in dendritic cells (DCs). These observations of differential regulatory functions prompted us to investigate MK2 in the context of DCs and other myeloid cells in the tumor microenvironment.Murine DCs lacking MK2 activity exhibit an enhanced potential to differentiate Th1 cells upon Toll-like receptor (TLR) ligation in vitro and in vivo. In line with this finding, we observe significantly reduced B16.F10 melanoma growth in CD11cCre-MK2fl/fl mice upon DC activation by administration of lipopolysaccharide (LPS) together with whole tumor cell lysate as compared to wildtype littermate controls. Interestingly, CD11cCre-MK2fl/fl mice show an overall reduced myeloid cell tumor infiltration. Looking at MK2 expression in DCs isolated from orthotopic B16.F10 tumor-bearing mice, we find elevated MK2 levels in tumor-resident as opposed to splenic DCs, which has also been confirmed in a model of intracranial glioma (GL-261). This MK2 up-regulation in glioma-infiltrating DCs is associated with an enhanced expression of IL-10. Furthermore, tumor-resident myeloid-derived suppressor cells (MDSCs) show elevated MK2 expression, further underlining its potential involvement in immunosuppressive mechanisms in the myeloid lineage. In DCs we have observed cross-regulation of MAPK signaling by MK2, which promotes ERK1/2 while attenuating p38 activation and is further implicated to enhance STAT3 phosphorylation – all together contributing to a tolerogenic DC phenotype. Therefore we are now looking to unravel mechanisms by which MK2 impacts on signaling networks involved in myeloid immunosuppression in the tumor microenvironment.Our data contrast the previously described role of MK2 in pro-inflammatory mechanisms of the p38 signaling route and suggest an additional immunosuppressive feedback function in myeloid cells, which might be exploited by tumor cells to escape immune recognition and elimination. These indications are particularly interesting with regard to glioma, since the glioma microenvironment has been shown to be rich in various cytokines promoting favourable conditions for tumor growth. Finally, MK2 represents a promising target for combination therapy, as it has been reported to mediate chemo- as well as radioresistance in different types of tumors. Nevertheless, its function in tumor-infiltrating immune cells remains to be elucidated. We therefore aim to contribute to a deeper understanding of the complex interplay between extra- and intracellular signaling molecules regulating tumor as well as immune cell phenotypes.Citation Format: Klara Soukup, Angela Halfmann, Fiona Poyer, Katharina Martin, Bernadette Blauensteiner, Bastien Huber, Mario Kuttke, Gernot Schabbauer, Lydia Zopf, Jelena Zinnanti, Alexander Michael Dohnal. MAPK-activated protein kinase MK2 exerts immune regulatory functions in the microenvironment of orthotopic tumors. [abstract]. In: Proceedings of the AACR Special Conference: Function of Tumor Microenvironment in Cancer Progression; 2016 Jan 7–10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2016;76(15 Suppl):Abstract nr A43.
Friday, July 22, 2016 8:03 AM|Dalin, M. G., Desrichard, A., Katabi, N., Makarov, V., Walsh, L. A., Lee, K.-W., Wang, Q., Armenia, J., West, L., Dogan, S., Wang, L., Ramaswami, D., Ho, A. L., Ganly, I., Solit, D. B., Berger, M. F., Schultz, N. D., Reis-Filho, J. S., Chan, T. A., Morris, L. G. T.|Clinical Cancer Research Online First Articles|Labels: MapK, P53, salivary duct cancer

Purpose: Salivary duct carcinoma (SDC) is an aggressive salivary malignancy, which is resistant to chemotherapy and has high mortality rates. We investigated the molecular landscape of SDC, focusing on genetic alterations and gene expression profiles.

Experimental Design: We performed whole-exome sequencing, RNA sequencing, and immunohistochemical analyses in 16 SDC tumors and examined selected alterations via targeted sequencing of 410 genes in a second cohort of 15 SDCs.

Results: SDCs harbored a higher mutational burden than many other salivary carcinomas (1.7 mutations/Mb). The most frequent genetic alterations were mutations in TP53 (55%), HRAS (23%), PIK3CA (23%), and amplification of ERBB2 (35%). Most (74%) tumors had alterations in either MAPK (BRAF/HRAS/NF1) genes or ERBB2. Potentially targetable alterations based on supportive clinical evidence were present in 61% of tumors. Androgen receptor (AR) was overexpressed in 75%; several potential resistance mechanisms to androgen deprivation therapy (ADT) were identified, including the AR-V7 splice variant (present in 50%, often at low ratios compared with full-length AR) and FOXA1 mutations (10%). Consensus clustering and pathway analyses in transcriptome data revealed striking similarities between SDC and molecular apocrine breast cancer.

Conclusions: This study illuminates the landscape of genetic alterations and gene expression programs in SDC, identifying numerous molecular targets and potential determinants of response to AR antagonism. This has relevance for emerging clinical studies of ADT and other targeted therapies in SDC. The similarities between SDC and apocrine breast cancer indicate that clinical data in breast cancer may generate useful hypotheses for SDC. Clin Cancer Res; 1–11. ©2016 AACR.

Wednesday, May 18, 2016 6:00 PM|Kathleen Gallo|Cancers|Labels: MapK
Mixed-lineage kinase 3 (MLK3) was first cloned in 1994; however, only in the past decade has MLK3 become recognized as a player in oncogenic signaling. MLK3 is a mitogen-activated protein kinase kinase kinase (MAP3K) that mediates signals from several cell surface receptors including receptor tyrosine kinases (RTKs), chemokine receptors, and cytokine receptors. Once activated, MLK3 transduces signals to multiple downstream pathways, primarily to c-Jun terminal kinase (JNK) MAPK, as well as to extracellular-signal-regulated kinase (ERK) MAPK, P38 MAPK, and NF-κB, resulting in both transcriptional and post-translational regulation of multiple effector proteins. In several types of cancer, MLK3 signaling is implicated in promoting cell proliferation, as well as driving cell migration, invasion and metastasis.
Monday, May 16, 2016 9:52 AM|Francica, P., Nisa, L., Aebersold, D. M., Langer, R., Bladt, F., Blaukat, A., Stroka, D., Rodriguez Martinez, M., Zimmer, Y., Medova, M.|Clinical Cancer Research Online First Articles|Labels: MapK, gastric

Purpose: Deregulated signaling via the MET receptor tyrosine kinase is abundant in gastric tumors, with up to 80% of cases displaying aberrant MET expression. A growing body of evidence suggests MET as a potential target for tumor radiosensitization. Experimental Design: Cellular proliferation and DNA damage-induced senescence were studied in a panel of MET-overexpressing human gastric cancer cell lines as well as in xenograft models following MET inhibition and/or ionizing radiation. Pathways activation and protein expression were assessed by immunoblotting and immunohistochemistry. Tumor tissue microarrays (91 gastric cancer patients) were generated and copy number alteration (178 patients) and gene expression (373 patients) data available at The Cancer Genome Atlas were analyzed to assess co-alterations of MET and FOXM1. Results: MET targeting administered prior ionizing radiation instigates DNA damage-induced senescence (~80%, P<0.001) rather than cell death. MET inhibition-associated senescence is linked to blockade of the MAPK pathway, correlates with downregulation of FOXM1 and can be abrogated (11,8% vs. 95,3%, P<0.001) by ectopic expression of FOXM1 in the corresponding gastric tumor cells. Cells with ectopic FOXM1 expression demonstrate considerable (~20%, P<0.001) growth advantage despite MET targeting, suggesting a novel clinically-relevant resistance mechanism to MET inhibition as the co-presence of both MET and FOXM1 protein (33%) and mRNA (30%) overexpression as well as gene amplification (24,7%) is common in patients with gastric cancer. Conclusions: FOXM1, a negative regulator of senescence, has been identified as a key downstream effector and potential clinical biomarker that mediates MET signaling following infliction of DNA damage in gastric tumors.

Thursday, May 12, 2016 10:05 PM|Toste, P. A., Nguyen, A. H., Kadera, B. E., Duong, M., Wu, N., Gawlas, I., Tran, L. M., Bikhchandani, M., Li, L., Patel, S. G., Dawson, D. W., Donahue, T. R.|Molecular Cancer Research recent issues|Labels: MapK, pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) has a characteristically dense stroma comprised predominantly of cancer-associated fibroblasts (CAF). CAFs promote tumor growth, metastasis, and treatment resistance. This study aimed to investigate the molecular changes and functional consequences associated with chemotherapy treatment of PDAC CAFs. Chemoresistant immortalized CAFs (R-CAF) were generated by continuous incubation in gemcitabine. Gene expression differences between treatment-naïve CAFs (N-CAF) and R-CAFs were compared by array analysis. Functionally, tumor cells (TC) were exposed to N-CAF– or R-CAF–conditioned media and assayed for migration, invasion, and viability in vitro. Furthermore, a coinjection (TC and CAF) model was used to compare tumor growth in vivo. R-CAFs increased TC viability, migration, and invasion compared with N-CAFs. In vivo, TCs coinjected with R-CAFs grew larger than those accompanied by N-CAFs. Genomic analysis demonstrated that R-CAFs had increased expression of various inflammatory mediators, similar to the previously described senescence-associated secretory phenotype (SASP). In addition, SASP mediators were found to be upregulated in response to short duration treatment with gemcitabine in both immortalized and primary CAFs. Inhibition of stress-associated MAPK signaling (P38 MAPK or JNK) attenuated SASP induction as well as the tumor-supportive functions of chemotherapy-treated CAFs in vitro and in vivo. These results identify a negative consequence of chemotherapy on the PDAC microenvironment that could be targeted to improve the efficacy of current therapeutic regimens.

Implications: Chemotherapy treatment of pancreatic cancer–associated fibroblasts results in a proinflammatory response driven by stress-associated MAPK signaling that enhances tumor cell growth and invasiveness. Mol Cancer Res; 14(5); 437–47. ©2016 AACR.

Tuesday, March 8, 2016 7:36 AM|Pandzic, T., Larsson, J., He, L., Kundu, S., Ban, K., Akhtar-Ali, M., Hellström, A. R., Schuh, A., Clifford, R., Blakemore, S. J., Strefford, J. C., Bauman, T. S., Lopez-Guillermo, A., Campo, E., Ljungström, V., Mansouri, L., Rosenquist, R., Sjöblom, T., Hellström, M.|Clinical Cancer Research Online First Articles|Labels: MapK, CLL

Purpose: To identify resistance mechanisms for the chemotherapeutic drug fludarabine in chronic lymphocytic leukemia (CLL), as innate and acquired resistance to fludarabine-based chemotherapy represents a major challenge for long-term disease control. Experimental Design: We employed piggyBac transposon-mediated mutagenesis, combined with next-generation sequencing, to identify genes that confer resistance to fludarabine in a human CLL cell line. Results: In total, this screen identified 782 genes with transposon integrations in fludarabine-resistant pools of cells. One of the identified genes is a known resistance mediator DCK (deoxycytidine kinase), which encodes an enzyme that is essential for the phosphorylation of the pro-drug to the active metabolite. BMP2K, a gene not previously linked to CLL, was also identified as a modulator of response to fludarabine. In addition, ten out of 782 transposon-targeted genes had previously been implicated in treatment resistance based on somatic mutations seen in patients refractory to fludarabine-based therapy. Functional characterization of these genes supported a significant role for ARID5B and BRAF in fludarabine sensitivity. Finally, pathway analysis of transposon-targeted genes and RNA-seq profiling of fludarabine-resistant cells suggested deregulated MAPK signaling as involved in mediating drug resistance in CLL. Conclusions: To our knowledge, this is the first forward genetic screen for chemotherapy resistance in CLL. The screen pinpointed novel genes and pathways involved in fludarabine resistance along with previously known resistance mechanisms. Transposon screens can therefore aid interpretation of cancer genome sequencing data in the identification of genes modifying sensitivity to chemotherapy

Monday, March 7, 2016 4:00 PM|Biochemical and Biophysical Research communications|MedWorm: Cancer Therapy|Comments|Labels: MapK
In this study, we analyzed the gene expression profiles of gynecological CSCs/CICs isolated as aldehyde dehydrogenase high (ALDH(high)) cells, and found that MAPK13, PTTG1IP, CAPN1 and UBQLN2 were preferentially expressed in CSCs/CICs. MAPK13 is expressed in uterine, ovary, stomach, colon, liver and kidney cancer tissues at higher levels compared with adjacent normal tissues. MAPK13 gene knockdown using siRNA reduced the ALDH(high) population and abrogated the tumor-initiating ability. These results indicate that MAPK13 is expressed in gynecological CSCs/CICs and has roles in the maintenance of CSCs/CICs and tumor-initiating ability, and MAPK13 might be a novel molecular target for treatment-resistant CSCs/CICs. PMID: 26969274 [PubMed - as supplied by publisher] (Source: Biochemical an...

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Friday, January 29, 2016 8:39 PM|Oncotarget|MedWorm: Non-Small Cell Lung Cancer|Comments|Labels: MapK, ROS, lung cancer
Authors: Xie D, Wu X, Lan L, Shangguan F, Lin X, Chen F, Xu S, Zhang Y, Chen Z, Huang K, Wang R, Wang L, Song X, Liu Y, Lu B Abstract Mitochondrial transcription factor A (TFAM) is essential for the replication, transcription and maintenance of mitochondrial DNA (mtDNA). The role of TFAM in non-small cell lung cancer (NSCLC) remains largely unknown. Herein, we report that downregulation of TFAM in NSCLC cells resulted in cell cycle arrest at G1 phase and significantly blocked NSCLC cell growth and migration through the activation of reactive oxygen species (ROS)-induced c-Jun amino-terminal kinase(JNK)/p38 MAPK signaling and decreased cellular bioenergetics. We further found that TFAM downregulation in NSCLC cells led to increased apoptotic cell death and enhanced the sensitivity o...
Sunday, January 24, 2016 1:59 AM|Oncotarget|MedWorm: Non-Small Cell Lung Cancer|Comments|Labels: MapK, lung cancer
This study determined the signaling pathway that contributes to PTX resistance. We first established PTX resistant cell lines (H460/R and 226B/R) using a dose-escalating maintenance of PTX. We found that p38 MAPK and epidermal growth factor receptor (EGFR) were constitutively activated in these cell lines. The inhibition of p38 MAPK activity by SB203580 treatment or the transfection of dominant-negative p38 MAPK sensitized both cell lines to PTX treatment. Erlotinib, an EGFR inhibitor, also increased PTX-induced apoptosis in PTX resistant cells, which suggests a role for p38 MAPK and EGFR in the development of PTX resistance. We demonstrated that p38 MAPK enhanced EGFR expression via the induction of the rapid degradation of mouse double-minute 2 homolog (MDM2) and the consequent stabiliza...
Wednesday, January 20, 2016 4:00 PM|Tumor Biology|MedWorm: Non-Small Cell Lung Cancer|Comments|Labels: MapK, ROS, lung cancer
In this study, we investigated whether fisetin can induce endoplasmic reticulum (ER) stress-mediated apoptosis in NCI-H460 cells. Fisetin induced mitochondrial reactive oxygen species (ROS) and characteristic signs of ER stress: ER staining; mitochondrial Ca2+ overload; expression of ER stress-related proteins; glucose-regulated protein (GRP)-78, phosphorylation of protein kinase RNA (PKR)-like endoplasmic reticulum kinase (PERK) and phosphorylation of eukaryotic initiation factor-2 α subunit; cleavage of activating transcription factor-6; phosphorylation of inositol-requiring kinase-1 and splicing of X-box transcription factor-1; induction of C/EBP homologous protein and cleaved caspase-12. siRNA-mediated knockdown of CHOP and ATF-6 attenuated fisetin-induced apoptotic cell death. In add...