Repression of AXL expression by AP-1/JNK blockage overcomes resistance to PI3Ka therapy
Mai Badarni, Manu Prasad, Noa Balaban, Jonathan Zorea, Ksenia M. Yegodayev, Ben-Zion Joshua, Anat Bahat Dinur, Reidar Grénman, Barak Rotblat, Limor Cohen, Moshe Elkabets
Mai Badarni, Manu Prasad, Noa Balaban, Jonathan Zorea, Ksenia M. Yegodayev, Ben-Zion Joshua, Anat Bahat Dinur, Reidar Grénman, Barak Rotblat, Limor Cohen, Moshe Elkabets
View: Text | PDF
Research Article Oncology Therapeutics

Repression of AXL expression by AP-1/JNK blockage overcomes resistance to PI3Ka therapy

Abstract

AXL overexpression is a common resistance mechanism to anticancer therapies, including the resistance to BYL719 (Alpelisib) — the p110α isoform specific inhibitor of phosphoinositide 3-kinase (PI3K) — in esophagus squamous cell carcinoma (ESCC) and head and neck squamous cell carcinoma (HNSCC). However, the mechanisms underlying AXL overexpression in resistance to BYL719 remain elusive. Here, we demonstrate that the AP-1 transcription factors c-JUN and c-FOS regulate AXL overexpression in HNSCC and ESCC. The expression of AXL was correlated with that of c-JUN both in HNSCC patients and in HNSCC and ESCC cell lines. Silencing of c-JUN and c-FOS expression in tumor cells downregulated AXL expression and enhanced the sensitivity of human papilloma virus–positive (HPVPos) and –negative (HPVNeg) tumor cells to BYL719 in vitro. Blocking of JNK using SP600125 in combination with BYL719 showed a synergistic antiproliferative effect in vitro, which was accompanied by AXL downregulation and potent inhibition of the mTOR pathway. In vivo, the BYL719–SP600125 drug combination led to the arrest of tumor growth in cell line–derived and patient-derived xenograft models, as well as in syngeneic head and neck murine cancer models. Collectively, our data suggest that JNK inhibition, in combination with anti-PI3K therapy, is a new therapeutic strategy that should be tested in HPVPos and HPVNeg HNSCC and ESCC patients.

Authors

Mai Badarni, Manu Prasad, Noa Balaban, Jonathan Zorea, Ksenia M. Yegodayev, Ben-Zion Joshua, Anat Bahat Dinur, Reidar Grénman, Barak Rotblat, Limor Cohen, Moshe Elkabets

×

Figure 6

SP600125 increases BYL719 efficacy in vivo in syngeneic head and neck cancer models.

Options: View larger image (or click on image) Download as PowerPoint
SP600125 increases BYL719 efficacy in vivo in syngeneic head and neck ca...
(A) IHC staining showing the expression of Ki67, pAKT, AXL, c-JUN, and keratin-14 (KRT14) in the 4NQO-induced tongue tumor region. Scale bars: 1000 μm (left) in the small magnification image of whole tongue and 50 μm (right) for the higher-magnification images. (B) Proliferation assay of 4NQO-induced tumor cell lines from the tongue and lips following 4 days of treatment with BYL719 (2 μM), SP600125 (5 and 10 μM), or the BYL719–SP600125 combination (n > 10). (C) WB analysis of tongue and lip 4NQO-induced tumor cell lines after 24 hours with the indicated treatments, showing activation of the AKT/mTOR pathway. (D) Survival rates of immunocompetent C57BL/6 mice (n = 5–6) in an orthotopic tongue cancer model following daily treatments with BYL719 (25 mg/kg), SP600125 (15 mg/kg), or the BYL719–SP600125 combination. Also presented are T2 weighted coronal images (obtained from the MRI) of tongues (lower panel), showing the difference in tumor progression following 10 days of treatments. Tumor margin, yellow. (E) Tumor growth (n = 8–10) of immunocompetent C57BL/6 mice bearing a syngeneic lip cancer model, treated as indicated in D. WB analysis was assessed in 2–3 independent experiments. One-way ANOVA. *P < 0.05; **P < 0.01; ***P < 0.001.