Abstract 2910: The dual role of autophagy in cadmium induced prostate carcinogenesis

Abstract

Abstract Cadmium chloride (Cd) and cadmium products cause both acute and chronic cytotoxicity and Cd exposure correlates with the risk of cancer, especially prostate cancer in humans. On the cellular and molecular level, Cd compounds may promote transformation of healthy cells to a malignant state by inducing expression of pro-survival signaling molecules. However, the precise molecular mechanism by which Cd affects cellular transformation in different tissue types, especially in prostate, is yet to be delineated. Autophagy is an intracellular lysosomal degradation process by which cells remove damaged organelles and maintain the integrity of intracellular components. In cancer cells, autophagy promotes cancer cell survival as well as cell death. It is unclear of how, and under what circumstances, these dual and opposite roles of autophagy affect both anti-oncogenic and oncogenic functions. It is possible that uncharacterized molecular switch that influences the anti-oncogenic function of autophagy in healthy cells to become oncogenic. In our studies, we found that exposure of normal prostate epithelial cells (RWPE-2) in culture to Cd (10μM) results in growth inhibition. By contrast, the growth of Cd-transformed prostate epithelial (CTPE) cells was not inhibited by the same Cd treatment. While analyzing the molecular link between Cd induced toxicity and generation of reactive oxygen species (ROS) generation in RWPE-2 and CTPE cells; we found there was no significant change in the ROS induction in both cell types. In addition, no changes in the expression of autophagy targeted genes (Atg family proteins) were seen in Cd treated in both non-transformed and transformed cells. However, microtubule-associated protein 1A/1B-light chain 3B (LC-3B), which is directly involved in autophagy initiation was upregulated in Cd-treated non-transformed cells, but not in Cd-treated transformed cells. LC-3B activation also correlated with growth inhibition in non-transformed cells, while impairing LC-3B activation in RWPE-2 cells causes resistance to CD induced growth inhibition. Our ongoing study will determine whether induction of autophagy via LC-3B is a key event that facilitates Cd-mediated conversion of non-transformed prostate epithelial cells to a malignant state. We strongly believe our studies will define a new concept of LC-3B mediated autophagy in Cd-induced prostate carcinogenesis. Citation Format: Trinath P. Das, Arokya MS John, Suman Suman, Murali Ankem, Chendil Damodaran. The dual role of autophagy in cadmium induced prostate carcinogenesis. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2910. doi:10.1158/1538-7445.AM2015-2910