Abstract 1013: Mechanistic role of nelfinavir as drug-repurposing strategy against high-grade serous ovarian cancer

Abstract

Abstract Platinum-based therapy following tumor-debulking surgery has been the backbone of treatment for high-grade serous ovarian cancer (HGSOC) since the 1970s; however, high recurrence of platinum-resistant disease necessitates the development of improved alternative therapies. Repurposing market-available drugs as cancer therapeutics carries the prospect of reducing the timeframe and cost of drug development, posing potential benefits to drug-resistant as well as financially underprivileged patients. Nelfinavir (NFV), an orally available anti-HIV drug, has shown promising effects against diverse cancers as demonstrated through a myriad of pre-clinical studies and clinical trials; however, its remedial benefits against HGSOC are still unclear. In this study, we explored the therapeutic efficacy of NFV on HGSOC cells generated from patients when platinum sensitive or resistant. Acute drug toxicity was assessed by total cell count, percent viability, and the level of hypo-diploid DNA content following 72 h of treatment with NFV. Living cells that tolerated 72 h of NFV treatment were subjected to further drug-free re-incubation for 14-21 days, to assess the residual anti-clonogenic potential of the drug. NFV triggered a dose-depended reduction of total cell number and viability, with a parallel increased hypo-diploid DNA content in both platinum-sensitive and resistant HGSOC cells. A dose-dependent reduction in the number of colonies - originating from cells that evaded acute toxicity - suggested long-term residual toxicity of NFV. Western blot analysis of underlying molecular mechanisms revealed phosphorylation of γH2AX, which suggested NFV-mediated induction of DNA damage. NFV also inhibited proliferation signals by reducing the phosphorylation of Akt and ERK. Moreover, NFV stimulated endoplasmic reticulum (ER) stress in a dose-dependent manner, which was evident from the enhanced expression of GRP78, IRE1α, ATF4, CHOP, and phosphorylated eIF2α. A time-dependent steady increase of ATF4 and CHOP suggested a progressive temporal apoptotic shift during NFV treatment. Finally, the cleavage of caspases-3 and -7 and their downstream effector PARP, in association with increased pro-apoptotic protein BAX, indicated caspase-associated cell-death during NFV-mediated cytotoxicity. In summary, we demonstrated that HGSOC cells of differential platinum sensitivities could be therapeutically targeted by NFV via multipronged mechanistic approaches, encouraging its prospective repurposing benefit against HGSOC. Citation Format: Mahbuba R. Subeha, Alicia A. Goyeneche, Carlos M. Telleria. Mechanistic role of nelfinavir as drug-repurposing strategy against high-grade serous ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1013.