Targeted induction of endogenous NKX3-1 by small activating RNA inhibits prostate tumor growth

• Published in: The Prostate 2013-10, Vol.73 (14), p.1591-1601
• Main Authors: Ren, Shancheng, Kang, Moo Rim, Wang, Ji, Huang, Vera, Place, Robert F., Sun, Yinhao, Li, Long-Cheng
• Format: Article
• Language: English
• Subjects: Animals; Cell Line, Tumor; Cell Physiological Phenomena - drug effects; Cell Physiological Phenomena - genetics; Genes, Tumor Suppressor; Homeodomain Proteins - genetics; Homeodomain Proteins - pharmacology; Humans; Male; Mice; Models, Animal; NKX3-1; Plasmids; Prostate - metabolism; Prostate - pathology; prostate cancer; Prostatic Neoplasms - genetics; Prostatic Neoplasms - metabolism; Prostatic Neoplasms - pathology; RNA, Double-Stranded - genetics; RNA, Double-Stranded - pharmacology; RNAa; saRNA; Transcription Factors - genetics; Transcription Factors - pharmacology; Transcriptional Activation - drug effects; Transfection; Transplantation, Heterologous; Treatment Outcome; xenograft
• ISSN: 0270-4137; 1097-0045
• DOI: 10.1002/pros.22709

BACKGROUND RNA activation (RNAa) is a small RNA‐mediated gene regulation mechanism by which expression of a particular gene can be induced by targeting its promoter using small double‐stranded RNA also known as small activating RNA (saRNA). We used saRNA as a molecular tool to examine NKX3‐1's role as a tumor suppressor and tested in vitro and in vivo antitumor effects of NKX3‐1 induction by saRNA. MATERIALS AND METHODS NKX3‐1 saRNA was transfected into human prostate cancer cells including LNCaP, CWR22R, PC‐3, CWR22RV1, DuPro, LAPC4, and DU145. The transfected cells were used for analysis of gene expression by RT‐PCR and immunoblotting, proliferation, apoptosis and cell cycle distribution. PC‐3 xenograft models were established in immunocompromised mice and treated with NKX3‐1 saRNA. RESULTS NKX3‐1 saRNA induced NKX3‐1 expression in different prostate cancer cell lines, resulting in inhibited cell proliferation and survival, cell cycle arrest and apoptotic cell death. These effects were partly mediated by NKX3‐1's regulation of several downstream genes including the upregulation of p21 and p27, and the inhibition of VEGFC expression. Treatment of mouse xenograft prostate tumors with intratumoral delivery of NKX3‐1 saRNA formulated in lipid nanoparticles significantly inhibited tumor growth and prolonged animal survival. CONCLUSIONS By revealing several important target genes of NKX3‐1, our findings corroborated NKX3‐1's role as a tumor suppressor gene through direct regulation of the cell cycle and growth/survival pathways. This study also validated the therapeutic potential of saRNA for the treatment of prostate cancer via targeted activation of tumor suppressor genes. Prostate 73: 1591–1601, 2013 © 2013 Wiley Periodicals, Inc.