Combined FAK and MEK inhibition suppresses chromosome 8 gain malignant peripheral nerve sheath tumors
Guangfeng Wang, Dana C. Borcherding, Jiawan Wang, Xiaochun Zhang, Liuzhan Yang, Gorkem Oztosun, James J. Sears, Kangwen Xiao, Belinda B. Garana, Mark I. Zoberi, Aaron U. Bektas, Jeffrey J. Szymanski, Richa Rathore, Silvia Coma, Jonathan A. Pachter, Sara J.C. Gosline, Christine A. Pratilas, Angela C. Hirbe
Guangfeng Wang, Dana C. Borcherding, Jiawan Wang, Xiaochun Zhang, Liuzhan Yang, Gorkem Oztosun, James J. Sears, Kangwen Xiao, Belinda B. Garana, Mark I. Zoberi, Aaron U. Bektas, Jeffrey J. Szymanski, Richa Rathore, Silvia Coma, Jonathan A. Pachter, Sara J.C. Gosline, Christine A. Pratilas, Angela C. Hirbe
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Research Article Cell biology Oncology

Combined FAK and MEK inhibition suppresses chromosome 8 gain malignant peripheral nerve sheath tumors

Abstract

Aneuploidy is a hallmark of cancer often associated with inferior prognosis. Copy number gains of chromosome 8 (chr8) are recurrent in multiple cancers, including breast, prostate, and colorectal cancers, and sarcomas, such as malignant peripheral nerve sheath tumors (MPNSTs). MPNSTs are aggressive, hard-to-treat sarcomas frequently linked to the neurofibromatosis type 1 (NF1) cancer predisposition syndrome. To investigate the role of chr8 gain in MPNST pathogenesis, we performed a CRISPR-knockout screen and identified 58 essential genes on chr8, including PTK2, which encodes focal adhesion kinase (FAK). We evaluated FAK as a therapeutic target and tested small-molecule FAK inhibitors (FAKi) alone or combined with RAF/MEK inhibitors (RAF/MEKi), a class of agents relevant to NF1-deficient tumors with ERK pathway hyperactivation. Both pharmacological and genetic inhibition of FAK reduced MPNST cell proliferation in vitro and tumor growth in vivo. Combined FAKi and RAF/MEKi treatment further suppressed phosphorylation of FAK, STAT3, and AKT while increasing cleaved caspase-3 and poly (ADP-ribose) polymerase 1 (PARP-1), indicating enhanced apoptosis. In MPNST patient-derived xenograft (PDX) models, combination therapy significantly reduced tumor growth, showing superior efficacy, particularly in chr8 gain MPNST PDX. These results support FAK/RAF/MEK cotargeting as a promising therapeutic strategy for chr8 gain MPNST and related tumors.

Authors

Guangfeng Wang, Dana C. Borcherding, Jiawan Wang, Xiaochun Zhang, Liuzhan Yang, Gorkem Oztosun, James J. Sears, Kangwen Xiao, Belinda B. Garana, Mark I. Zoberi, Aaron U. Bektas, Jeffrey J. Szymanski, Richa Rathore, Silvia Coma, Jonathan A. Pachter, Sara J.C. Gosline, Christine A. Pratilas, Angela C. Hirbe

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Figure 2

Knockdown of PTK2 inhibits cell proliferation and tumorigenesis of MPNST cells.

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Knockdown of PTK2 inhibits cell proliferation and tumorigenesis of MPNST...
(A) Reverse transcription-PCR (RT-PCR) results demonstrated a significant decrease in PTK2 mRNA in murine MPNST cells (JW23.3) and human MPNST cells (JH-2-002 and WU-356) following PTK2 knockdown by shRNA. Statistical significance was determined using 1-way ANOVA followed by Tukey’s post hoc test for multiple-group comparisons. (B) FAK protein expression is decreased with PTK2 shRNA knockdown in MPNST cell lines JW23.3, JH-2-002, and WU-356, as determined by Western blot (Simple WES) analysis. (C) Cell confluence over time after PTK2 knockdown in MPNST cell lines JW23.3, JH-2-002, and WU-356. Cell confluence was monitored over time using the Incucyte system. Statistical significance was determined using 1-way ANOVA followed by Tukey’s post hoc test for multiple-group comparisons. (D) Representative images of Incucyte assay for JH-2-002 cells at 0 hour and 144 hours. (E) PTK2 knockdown via shRNA prolonged survival in the MPNST cell JH-2-002 orthotopic mouse model. Kaplan-Meier survival analysis of nude mice injected orthotopically with 1 × 105 JH-2-002 cells (5 μL) into the sciatic nerve, showing prolonged survival in the PTK2-knockdown groups. Survival distributions were compared using the log-rank (Mantel-Cox) test. (F) Histological (H&E) and immunohistochemical (Ki67 and FAK) staining of nerve tumor tissues. Scale bar, 50 μm. (G) IHC staining was quantified using ImageJ (NIH; http://imagej.org) by measuring integrated density or performing particle analysis. Statistical significance was determined using 1-way ANOVA followed by Tukey’s post hoc test for multiple-group comparisons.