Hyperthermia effects on Hsp27 and Hsp72 associations with mismatch repair (MMR) proteins and cisplatin toxicity in MMR-deficient/proficient colon cancer cell lines

SOTTILE M; ANTONELLA D. LOSINNO; FANELLI M.; CUELLO CARRIÓN FD; MM MONTT GUEVARA; VARGAS-ROIG L; NADIN S.;

INTERNATIONAL JOURNAL OF HYPERTHERMIA

INFORMA HEALTHCARE

Lugar: London; Año: 2015

0265-6736

Purpose: Hyperthermia is used in combination with conventional anticancer agents topotentiate their cytotoxicity. One of its key events is the synthesis of heat shock proteins(HSPs), which are able to associate with components from DNA repair mechanisms. However,little is known about their relationship with the mismatch repair system (MMR). Our aim was tostudy the effects of hyperthermia on cisplatin (cPt) sensitivity and to determine whether MLH1and MSH2 associate with Hsp27 and Hsp72 in MMR-deficient()/-proficient(+) cells.Materials and methods: HCT116+ch2 (MMR) and HCT116+ch3 (MMR+) cell lines were exposedto cPt with or without previous hyperthermia (42 C, 1 h). Clonogenic survival assays, MTT,confocal immunofluorescence, immunoprecipitation, immunoblotting and flow cytometrywere performed.Results: Hyperthermia increased the cPt resistance in MMR cells 1.42-fold. Immunofluorescencerevealed that after cPt, Hsp27 and Hsp72 translocated to the nucleus and colocalisationcoefficients between these proteins with MLH1 and MSH2 increased in MMR+ cells.Immunoprecipitation confirmed the interactions between HSPs and MMR proteins in controland treated cells. Hyperthermia pretreatment induced cell cycle arrest, increased p73 expressionand potentiated cPt sensitivity in MMR+ cells.Conclusions: This is the first report showing in a MMR/+ cellular model that MLH1 and MSH2are client proteins of Hsp27 and Hsp72. Our study suggests that p73 might participate in thecellular response to hyperthermia and cPt in a MMR-dependent manner. Further functionalstudies will confirm whether HSPs cooperate with the MMR system in cPt-induced DNA damageresponse or whether these protein interactions are only the result of their chaperone functions.Key