Abstract 5040: Involvement of PI3K/Akt pathway in cadmium triggered aggressive prostate cancer
Authors: Kulkarni Priyanka , Dasgupta Pritha , Bhat Nadeem S. , Hashimoto Yutaka , Saini Sharanjot , Dar Altaf A. , Shahryari Varahram , Shiina Marisa , Yamamura Soichiro , Tanaka Yuichiro , Dahiya Rajvir , Majid Shahana 
Published: August 2019

Abstract
Cadmium (Cd) has been implicated in cancer development and classified as a type I carcinogen by the International Agency for Cancer Research. The etiology of prostate cancer development is associated with multitude of causative risk factors including exposure to cadmium. However, the molecular mechanisms associated with Cd-induced prostate cancer remain elusive. This study provides evidence that PI3K/Akt signaling is a major molecular pathway involved in Cd induced malignant transformation of normal prostate epithelial cells. Functionally, Cd exposure induced aggressive behavior as indicated by increased proliferation, migration and invasion in Cd-RWPE1 cells compared to parental RWPE1. PI3K/Akt pathway is constitutively activated in prostate cancer driving the most aggressive forms of cancer and metastasis. Consistent with these findings, the RT2 PCR array analysis of 84 genes involved in the PI3K/Akt pathway revealed induction of gene expression in catalytic units (P110α, Akt, mTOR, NFKB1, RAF etc.) with a concomitant reduction in expression of regulatory units (PIK3R1, PIK3R2, PTEN etc.) of the PI3K/Akt pathway in Cd-RWPE1 cells compared to parental RWPE1. This was confirmed by individual quantitative real-time PCR analysis using TaqMan gene expression assay probes. Effect of Cd on the translation of the PI3K/Akt pathway genes was examined by immunoblot assays. Gene Set Enrichment Analysis (GSEA) for differentially expressed genes in Cd-RWPE1 showed 5 overlapping pathways that were enriched in Cd-treated cells (Cd-RWPE1) and negatively correlated with parental RWPE1. The overlapping pathways include KEGG Apoptosis pathway (ES=0.56, NES=1), KEGG ERBB pathway (ES=0.25, NES=1), KEGG MAPK pathway (ES=0.48, NES=1), KEGG Pathways in cancer (ES=0.33, NES=1) and KEGG Prostate Cancer pathway (ES=0.35, NES=1). Interestingly, all these pathways are implicated in prostate cancer progression and metastasis. We randomly selected up- and down-regulated genes from the PI3K/Akt pathway in PCR array and performed profile analysis in a prostate adenocarcinoma data set (n=534) from the TCGA/GDC data base. We observed upregulation of the oncogenes along with downregulation of tumor suppressors in prostate cancer compared to normal prostate samples. Taken together, these data reveal that Cd exposure induced aggressive malignant characteristics in normal prostate epithelial cells via modulation of the PI3K/Akt signaling pathway. Understanding the molecular mechanisms involved in the malignant transformation of normal prostate epithelial cells may help develop optimal therapeutic strategies for advanced prostate cancer.
Citation Format: Priyanka Kulkarni, Pritha Dasgupta, Nadeem S. Bhat, Yutaka Hashimoto, Sharanjot Saini, Altaf A. Dar, Varahram Shahryari, Marisa Shiina, Soichiro Yamamura, Yuichiro Tanaka, Rajvir Dahiya, Shahana Majid. Involvement of PI3K/Akt pathway in cadmium triggered aggressive prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 5040.