Abstract 1409: Inhibiting Neuropilin-2 overcomes resistance to enzalutamide in prostate cancer
Authors: Bodas Sanika , Islam Ridwan , Polavaram Navatha , Bhattacharya Sreyashi , Muders Michael , Dutta Samikshan , Teply Benjamin A. , Datta Kaustubh 
Published: July 2021

Abstract
INTRODUCTION:Patients with advanced prostate cancer often report resistance to standard ARSI (Androgen Receptor Signaling Inhibitor) therapy. One reason for such therapy resistance is the development of splice variants of Androgen Receptor (AR). Additionally, studies have reported AR-independent signaling axis to play an important role in conferring therapy resistance in these cancers. The purpose of this study is to explore the underlying molecular mechanisms of resistance and develop an alternate therapeutic strategy for such patients.OBJECTIVES: In this study we investigated the role of Neuropilin-2 (NRP2), a receptor protein often upregulated in advanced prostate cancer, in imparting therapy-resistance to ARSI treatment (like enzalutamide). The final objective of this study is to develop a treatment strategy which targets NRP2 along with Enzalutamide treatment to increase treatment efficacy in therapy-resistant prostate cancer.
METHODS: To establish the expression pattern of NRP2 in advanced prostate cancer, we analyzed a dataset of 396 patients with advanced prostate cancer. Immunohistochemistry was performed on tissue samples to observe NRP2 localization within the cancer cells. NRP2 was knocked down using two independent siRNAs in various prostate cancer cell lines to determine the effect of NRP2 inhibition on cancer growth and survival. The knockdown was validated by Western Blot and RT-PCR. The efficacy of NRP2 inhibition was quantitated by measuring cell death using YO-PRO-I and PI assay for cellular apoptosis. In vitro tumorigenicity of cells after NRP2 inhibition in combination with enzalutamide was assessed using soft agar colony formation assay.
RESULTS:Our patient datasets showed a significant upregulation of NRP2, as well as poor cancer-specific survival, in advanced prostate cancer patients with higher Gleason scores. Immunohistochemistry analyses revealed a markedly high expression of NRP2 in the nucleus of cancer cells. We found that NRP2 nuclear translocation enabled transcription of novel oncogenes by interacting with AR. Knockdown of NRP2 was shown to bring about increased cell death in vitro. Inhibiting NRP2 was also seen to reduce AR-regulated oncogenesis. Cancer cell tumorigenicity was significantly reduced when NRP2 was inhibited in combination with enzalutamide, as evidenced by the decreased number of colonies in our colony formation assay.
CONCLUSION:Our results indicate that inhibiting NRP2 in combination with enzalutamide sensitizes the cells to ARSI treatment. Thus, NRP2 inhibition along with enzalutamide can be further explored as a treatment option for patients with treatment-refractory prostate cancer.
Citation Format: Sanika Bodas, Ridwan Islam, Navatha Polavaram, Sreyashi Bhattacharya, Michael Muders, Samikshan Dutta, Benjamin A. Teply, Kaustubh Datta. Inhibiting Neuropilin-2 overcomes resistance to enzalutamide in prostate 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 1409.