HYPERTHERMIA MODULATES CISPLATIN SENSITIVITY

SOTTILE M.L.; CUELLO CARRIÓN, F.D.; VARGAS ROIG, L.M.; CIOCCA, D.R.; NADIN S.B.

Porto Alegre

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

Cell Stress Society International

Introduction. A mild hyperthermia (39-42°C) induces the expression of heat shock proteins (HSPs). HSPB1 (HSP27) and HSPA1A (HSP72) participate in cell proliferation and survival; they were also implicated in resistance to antineoplasic drugs, ie cisplatin (cPt).  The cytotoxicity of cPt is mediated by DNA-crosslinks formation; which are recognized by components of the Mismatch Repair system (MMR). Defects of MMR proteins, such as hMLH1 and hMSH2, have been related to cPt resistance. Recently, we have reported that hyperthermia induced the nuclear accumulation of HSPB1 and HSPA1A and affected the subcellular localization of hMLH1 and hMSH2 in MMR proficient colon cancer cells. However, the implications of HSPs on cisplatin DNA damage/repair mediated by MMR system have not been determined in MMR deficient/proficient tumor cell lines. HCT116 and HCT116+ch2 (MMR deficient) and HCT116+ch3 (MMR proficient) were exposed to: 1- cPt, 10 µM (1 h) and 2- HS+cPt, 10 µM (1 h) 24 h after HS (42°C, 1 h). Cells were collected after treatments at times: 0 (immediately after cPt), 4 and 24 h after cPt. Gene expressions were evaluated using qRT-PCR, DNA damage by alkaline comet assay, senescence by cytochemical detection of SA-âgal activity and apoptosis by TUNEL. Results. cPt reduced the expression of HSPB1 in HCT116+ch3 cells (P<0.001). The expression of HSPA1A increased 4 h after cPt (P<0.001) with or without hyperthermia in MMR deficient/proficient cell lines. However, the expression of hMSH2 decreased (P<0.001) in MMR proficient cells (cPt and HS+cPt groups).  24 h after cPt, heat shocked HCT116+ch3 cells (HS+cPt) showed increased expression of HSF1 (P<0.001) and hMLH1 (P<0.001), which were higher than in HCT116 cells (P<0.001). Hyperthermia reduced approximately 30% cPt crosslinks in HCT116+ch3 cells (P<0.001). After cPt treatment, senescence increased in heat shocked HCT116+ch3 cells (P<0.001). HCT116 cells (HS+cPt) showed higher apoptotic index than cells exposed to cPt alone (P<0.001) Conclusions. A mild heat shock before cPt exposure increased senescence in MMR proficient cells and apoptosis in MMR deficient cells, which may suggest that hyperthermia could improve cisplatin sensitivity in colon cancer cells by different mechanisms independently of MMR system status.