Effects of cadmium on the expression of beta-catenin, caveolin-1 and HSPs in ERalpha-positive and ERalpha-negative cancer cell lines

JORGE SHORTREDE; DAIANA ALVAREZ-OLMEDO; CUELLO-CARRIÓN F.D.; CIOCCA DR; FANELLI M.A.

Workshop; IX Cell Stress Society International Workshop on the Molecular Biology of Stress Responses; 2012

Effects of cadmium on the expression of β-catenin, caveolin-1 and HSPs in ERα-positive and ERα-negative cancer cell lines. Jorge Shortrede, Daiana G. Alvarez-Olmedo, F. Darío Cuello-Carrión, Daniel R. Ciocca and Mariel A. Fanelli. Oncology Laboratory, IMBECU, CCT-CONICET-Mendoza, Argentina. Introduction: The metal Cd is an environmental pollutant that enters the body through diet and cigarette smoke. It is a class 1 carcinogen associated with different human cancer types. Cd works at all stages of the oncogenic process through multiple non-exclusive mechanisms that affect different intracellular pathways. As a metalloestrogen, Cd acts via estrogen receptor α (ERα). However, ER-independent pathways are also affected. At the level of distal tubule cells of the kidney, Cd induced disruption of adherents junctions mediated by E-cadherin and β-catenin. In these cells, Cd induced β-catenin translocation from the cytoplasm to the nucleus promoting cell proliferation and survival. Protein location is emerging as a key factor to understand tumor cell biology. In addition, there are interactions of β-catenin with Hsp27 (HSPB1) and caveolin-1 (cav-1), proteins that are important in several regulatory pathways. Objetives: To evaluate the effects of Cd on the expression and localization of -catenin, Hsp27 and cav-1 in ERα positive and negatives cancer cells lines, correlating with cytotoxicity as well as with cell survival and apoptosis. Methodology: HeLa, MDA-MB-231 and MCF-7 cells were exposed to different CdCl2 concentrations (0, 1, 5, 10, 25, 50, 100 μM), during 3 hours. Cytotoxicity was evaluated by MTT and clonogenic assay. The localization and expression of -catenin, Hsp27 and cav-1 were evaluated by immunocytochemistry. Apoptosis was studied by the TUNEL and by the Bax/Bcl-2 ratio.Results: Cd treatment (100 μM) reduced the viability of HeLa cells to 26%, MDA-MB-231 to 84% and MCF-7 cells to 85%. Long term survival was inhibited in HeLa and MCF-7 at 10 and 50 μM CdCl2 respectively, while in MDA-MB-231 few colonies were detected at 100 μM CdCl2. Apoptosis did not change significantly in HeLa cells but significant changes were observed in MCF-7 cells line. With increasing CdCl2 concentrations -catenin acquired, in MDA-MB-231 cells, para/peri nuclear location, while in HeLa cells this protein showed an intricate distribution pattern. In MCF-7 β-catenin expression was modified passing from membrane to the cytoplasmic/peri-nuclear region. Cav-1 changed from a cytoplasmic distribution to a para-nuclear location in the three cell lines after Cd administration. In all cell lines Hsp27 expression was observed in the cytoplasm but Cd induced noticeable dots in the nuclei. Conclusions: Cd differentially modulated the distribution of β-catenin, cav-1 and Hsp27 in the ERα-positive and negative cancer cell lines. These changes might explain the differences in the viability and colony formation. Financial support: CONICET (PIP2428) and PICT 1047 (2007 BID).