CMTM6 drives cisplatin resistance by regulating Wnt signaling through the ENO-1/AKT/GSK3β axis
Pallavi Mohapatra, Omprakash Shriwas, Sibasish Mohanty, Arup Ghosh, Shuchi Smita, Sandeep Rai Kaushik, Rakesh Arya, Rachna Rath, Saroj Kumar Das Majumdar, Dillip Kumar Muduly, Sunil K. Raghav, Ranjan K. Nanda, Rupesh Dash
Pallavi Mohapatra, Omprakash Shriwas, Sibasish Mohanty, Arup Ghosh, Shuchi Smita, Sandeep Rai Kaushik, Rakesh Arya, Rachna Rath, Saroj Kumar Das Majumdar, Dillip Kumar Muduly, Sunil K. Raghav, Ranjan K. Nanda, Rupesh Dash
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Research Article Cell biology Oncology

CMTM6 drives cisplatin resistance by regulating Wnt signaling through the ENO-1/AKT/GSK3β axis

Abstract

Rewiring tumor cells to undergo drug-induced apoptosis is a promising way to overcome chemoresistance. Therefore, identifying causative factors for chemoresistance is of high importance. Unbiased global proteome profiling of sensitive, early, and late cisplatin-resistant oral squamous cell carcinoma (OSCC) lines identified CMTM6 as a top-ranked upregulated protein. Analyses of OSCC patient tumor samples demonstrated significantly higher CMTM6 expression in chemotherapy (CT) nonresponders as compared with CT responders. In addition, a significant association between higher CMTM6 expression and poorer relapse-free survival in esophageal squamous cell carcinoma, head and neck squamous cell carcinoma, and lung squamous cell carcinoma was observed from Kaplan-Meier plot analysis. Stable knockdown (KD) of CMTM6 restored cisplatin-mediated cell death in chemoresistant OSCC lines. Upon CMTM6 overexpression in CMTM6-KD lines, the cisplatin-resistant phenotype was rescued. The patient-derived cell xenograft model of chemoresistant OSCC displaying CMTM6 depletion restored the cisplatin-induced cell death and tumor burden substantially. The transcriptome analysis of CMTM6-KD and control chemoresistant cells depicted enrichment of the Wnt signaling pathway. We demonstrated that CMTM6 interaction with membrane-bound Enolase-1 stabilized its expression, leading to activation of Wnt signaling mediated by AKT–glycogen synthase kinase-3β. CMTM6 has been identified as a stabilizer of programmed cell death ligand 1. Therefore, as CMTM6 facilitates tumor cells for immune evasion and mediates cisplatin resistance, it could be a promising therapeutic target for treating therapy-resistant OSCC.

Authors

Pallavi Mohapatra, Omprakash Shriwas, Sibasish Mohanty, Arup Ghosh, Shuchi Smita, Sandeep Rai Kaushik, Rakesh Arya, Rachna Rath, Saroj Kumar Das Majumdar, Dillip Kumar Muduly, Sunil K. Raghav, Ranjan K. Nanda, Rupesh Dash

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Figure 4

CMTM6 KD restores cisplatin-induced cell death in drug-resistant OSCC.

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CMTM6 KD restores cisplatin-induced cell death in drug-resistant OSCC. (...
(A) Cisplatin-resistant cells stably expressing NTShRNA and CMTM6ShRNA were treated with cisplatin for 48 hours, after which cell death was determined by annexin V/7AAD assay using flow cytometer. Bar diagrams indicate the percentage of cell death with respective treated groups (mean ± SEM, n = 3). Two-way ANOVA. (B) Cisplatin-resistant cells stably expressing NTShRNA and CMTM6ShRNA were treated with cisplatin for 48 hours, and immunoblotting (n = 3) was performed with indicated antibodies. (C) Patient-derived cells (PDC1) established from tumor of CT nonresponder patient. PDC1 cells stably expressing NtShRNA were implanted in the right upper flank of athymic male nude mice, and PDC1 cells stably expressing CMTM6ShRNA#1 (PDC1 CMTM6KD) were implanted in the left upper flank, after which they were treated with cisplatin at indicated concentration. At the end of the experiment mice were euthanized, and tumors were isolated and photographed (n = 6). (D) Tumor growth was measured at the indicated time point using digital slide calipers and plotted as a graph (mean ± SEM, n = 6). Two-way ANOVA. (E) Bar diagram indicates the tumor weight measured at the end of the experiment (mean ± SEM, n = 6). Two-way ANOVA. (F) After completion of treatment, tumors were isolated, and paraffin-embedded sections were prepared as described in Methods to perform IHC with indicated antibodies. Scale bars: 50 μm.