HSP27 affects cisplatin-induced DNA damage response through ATR/CHK1 pathway in human colon cancer cells

ANALÍA REDONDO; LAURA VARGAS ROIG; ANTONELLA LOSSINO; SILVINA B. NADIN; NIUBYS CAYADO-GUTIÉRREZ; MARIEL FANELLI

Congreso; Reunión de Sociedades de Biociencias 2021. LXVI REUNIÓN ANUAL DE LA SOCIEDAD ARGENTINA DE INVESTIGACIÓN CLÍNICA (SAIC); 2021

HSP27 (HSPB1) is overexpressed in many tumor cells and has been involved with cancer progression and resistance to cancer therapy. Accordingly, HSP27 has become an attractive therapeutic target. Previously, we reported that HSP27 interacts with DNA mismatch repair (MMR) proteins after cisplatin (cPt) treatment. However, the role of HSP27 in cPt-induced DNA damage response (DDR) through ATR/CHK1 pathway in MMR deficient/proficient tumor cells remains unknown. Here, human colon cancer cell lines HCT116+ch2 (MMR deficient, MMR-) and HCT116+ch3 (MMR proficient, MMR+) were exposed to 10 μM of cPt for 24 h. Downregulation of HSP27 was performed using the antisense oligonucleotide (OGX427) and ATR/CHK1 inhibition by VE-821 (VE). Cells were collected at T0, T3, T9 and T24 (0, 3, 9 and 24 h post-cPt or cPt+VE, respectively). γH2AX (DNA double-strand breaks marker), HSP27 and phosphorylated CHK1 (pCHK1, Ser345) were analyzed by western blot and cell viability by CCK8. HSP27 downregulation significantly reduced the expression of γH2AX and pCHK1 after cPt treatment in MMR+ cells (P