Abstract AP14: THERAPEUTIC TARGETING USING TUMOR SPECIFIC PEPTIDES INHIBITS LONG NON–CODING RNA HOTAIR ONCOGENIC ACTIVITY IN OVARIAN CANCER

PURPOSE: Most women diagnosed with advanced-stage ovarian cancer develop chemo-resistant tumor recurrence, which is uniformly fatal. Long non-coding RNAs (lncRNAs) play key roles in human diseases, including cancer. Functional studies of the lncRNA HOTAIR (HOX transcript antisense RNA) provide compelling evidence for therapeutic targeting of HOTAIR in ovarian cancer to impact chemoresistance, but targeting lncRNAs in vivo has proven to be difficult. EXPERIMENTAL DESIGN: In the current study, we describe a peptide nucleic acids (PNA)-based approach to effectively block the ability of HOTAIR to interact with EZH2 and subsequently inhibit oncogenic HOTAIR-EZH2 activity. In order to deliver the anti-lncRNA to the acidic (pH approximately 6) microenvironment of solid tumors in vivo , PNAs were conjugated to pH-low insertion peptide (pHLIP). RESULTS: Treatment of HOTAIR-overexpressing ovarian cancer cell lines with PNAs decreased cancer cell invasion and increased chemotherapy sensitivity. The mechanism of action of the anti-lncRNA agent correlated with reduced nuclear factor-kappaB (NF-κB) activation and decreased expression of key NF-κB target genes including matrix metalloprotease 9 and interleukin 6. PNA treatment of ALDH1A1 positive/ovarian tumor initiating cells overexpressing HOTAIR markedly decreased ALDH1A1 activity and reduced the ovarian cancer stem cell population. In mice harboring ovarian tumor xerographs and treated with pHLIP-PNA constructs, HOTAIR oncogenic activity was suppressed, ovarian tumors were resensitized to platinum, and a significant (64%) survival improvement was observed. CONCLUSIONS: Toward developing new therapeutic approaches against chemoresistant ovarian cancer, we designed a PNA-targeting strategy for HOTAIR that effectively blocks the ability of HOTAIR to interact with EZH2 and inhibits oncogenic HOTAIR-EZH2. This first report on pHLIP-PNA targeting HOTAIR in vivo offer pre-clinical proof-of-concept and represents a possible treatment alternative for chemotherapy-resistant ovarian cancer. Citation Format: Ali R. Ozes, Yinu Wang, Fang Fang, and Kenneth P. Nephew. THERAPEUTIC TARGETING USING TUMOR SPECIFIC PEPTIDES INHIBITS LONG NON–CODING RNA HOTAIR ONCOGENIC ACTIVITY IN OVARIAN CANCER [abstract]. In: Proceedings of the 11th Biennial Ovarian Cancer Research Symposium; Sep 12-13, 2016; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2017;23(11 Suppl):Abstract nr AP14.