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Gene copy number alterations, tumor cell stemness, and the development of platinum chemotherapy resistance contribute to high-grade serous ovarian cancer (HGSOC) recurrence. Stem phenotypes involving Wnt-β-catenin, aldehyde dehydrogenase activities, intrinsic platinum resistance, and tumorsphere formation are here associated with spontaneous gains in Kras, Myc and FAK (KMF) genes in a new aggressive murine model of ovarian cancer. Adhesion-independent FAK signaling sustained KMF and human tumorsphere proliferation as well as resistance to cisplatin cytotoxicity. Platinum-resistant tumorspheres can acquire a dependence on FAK for growth. Accordingly, increased FAK tyrosine phosphorylation was observed within HGSOC patient tumors surviving neo-adjuvant chemotherapy. Combining a FAK inhibitor with platinum overcame chemoresistance and triggered cell apoptosis. FAK transcriptomic analyses across knockout and reconstituted cells identified 135 targets, elevated in HGSOC, that were regulated by FAK activity and β-catenin including Myc, pluripotency and DNA repair genes. These studies reveal an oncogenic FAK signaling role supporting chemoresistance.

Gene copy number alterations, tumor cell stemness, and the development of platinum chemotherapy resistance contribute to high-grade serous ovarian cancer (HGSOC) recurrence. Stem phenotypes involving Wnt-β-catenin, aldehyde dehydrogenase activities, intrinsic platinum resistance, and tumorsphere formation are here associated with spontaneous gains in Kras, Myc and FAK (KMF) genes in a new aggressive murine model of ovarian cancer. Adhesion-independent FAK signaling sustained KMF and human tumorsphere proliferation as well as resistance to cisplatin cytotoxicity. Platinum-resistant tumorspheres can acquire a dependence on FAK for growth. Accordingly, increased FAK tyrosine phosphorylation was observed within HGSOC patient tumors surviving neo-adjuvant chemotherapy. Combining a FAK inhibitor with platinum overcame chemoresistance and triggered cell apoptosis. FAK transcriptomic analyses across knockout and reconstituted cells identified 135 targets, elevated in HGSOC, that were regulated by FAK activity and β-catenin including Myc, pluripotency and DNA repair genes. These studies reveal an oncogenic FAK signaling role supporting chemoresistance.

Oncogenes provide tumor cells with a growth and survival advantage. Directed therapies targeted to oncogenic mutations (such as BRAF V600E) are part of effective late-stage melanoma treatment. However, tumors with BRAF V600E mutations, in approximately 10% of colorectal cancer, are generally treatment-insensitive. Research has identified various "feedback" mechanisms that result in BRAF signal pathway reactivation in response to BRAF inhibition. Herein, we highlight key findings from Chen and colleagues (this issue) showing that integrin-associated focal adhesion kinase (FAK) activation selectively occurs in BRAF V600E-mutant colorectal cancer cells in response to pharmacological BRAF inhibition. FAK activation results in elevated β-catenin protein levels, β-catenin nuclear localization, and increased gene transcription. Small-molecule inhibitors of β-catenin or FAK synergize with vemurafenib BRAF inhibitor to prevent BRAF V600E colorectal cancer cell proliferation in vitro and xenograft tumor growth in mice. This study complements findings linking FAK to β-catenin in intestinal tumorigenesis, resistance to radiotherapy, and cancer stem cell survival. Thus, FAK activation may occur as a frequent tumor cell "adaptive resistance" mechanism. Although FAK (PTK2) is not mutated in most cancers, targeting FAK activity in combinational approaches may limit tumor cell escape mechanisms and enhance durable responses to treatment. Mol Cancer Ther; 17(4); 719-23. ©2018 AACR.

Key content Gynaecological and breast cancers affect premenopausal and perimenopausal women at rates ranging 15-70% and treatment often causes the abrupt onset of menopause., Available studies do not show an increase in recurrence or decrease in survival among women with endometrial, ovarian or cervical cancer who use hormone replacement therapy (HRT)., Data regarding the risks of systemic HRT in survivors of breast cancer are varied, and an increase in breast cancer recurrence with the use of systemic HRT has been demonstrated in randomised controlled trials. Limited data exist regarding the use of vaginal estrogen, however, no effect on recurrence has been demonstrated., The decision regarding the use of HRT in women with cancer must be individualised and should take into account issues regarding quality of life., Learning objectives To review the evidence regarding the cancer-specific risks, that is, recurrence or death, of HRT in survivors of gynaecological and breast cancer., To provide recommendations for the use of HRT in survivors of gynaecological and breast cancer., Ethical issues How to balance the risks of HRT with quality of life concerns in survivors of gynaecological and breast cancer when evidence to guide our recommendations is limited? [ABSTRACT FROM AUTHOR]