Chloroquine reverses chemoresistance via upregulation of p21WAF1/CIP1 and autophagy inhibition in ovarian cancer

Abstract

Overcoming drug-resistance is a big challenge to improve the survival of patients with epithelial ovarian cancer (EOC). In this study, we investigated the effect of chloroquine (CQ) and its combination with cisplatin (CDDP) in drug-resistant EOC cells. We used the three EOC cell lines CDDP-resistant A2780-CP20, RMG-1 cells, and CDDP-sensitive A2780 cells. The CQ-CDDP combination significantly decreased cell proliferation and increased apoptosis in all cell lines. The combination induced expression of γH2AX, a DNA damage marker protein, and induced G2/M cell cycle arrest. Although the CQ-CDDP combination decreased protein expression of ATM and ATR, phosphorylation of ATM was increased and expression of p21WAF1/CIP1 was also increased in CQ-CDDP-treated cells. Knockdown of p21WAF1/CIP1 by shRNA reduced the expression of γH2AX and phosphorylated ATM and inhibited caspase-3 activity but induced ATM protein expression. Knockdown of p21WAF1/CIP1 partly inhibited CQ-CDDP-induced G2/M arrest, demonstrating that knockdown of p21WAF1/CIP1 overcame the cytotoxic effect of the CQ-CDDP combination. Ectopic expression of p21WAF1/CIP1 in CDDP-treated ATG5-shRNA/A2780-CP20 cells increased expression of γH2AX and caspase-3 activity, demonstrating increased DNA damage and cell death. The inhibition of autophagy by ATG5-shRNA demonstrated similar results upon CDDP treatment, except p21WAF1/CIP1 expression. In an in vivo efficacy study, the CQ-CDDP combination significantly decreased tumor weight and increased expression of γH2AX and p21WAF1/CIP1 in A2780-CP20 orthotopic xenografts and a drug-resistant patient-derived xenograft model of EOC compared with controls. These results demonstrated that CQ increases cytotoxicity in combination with CDDP by inducing lethal DNA damage by induction of p21WAF1/CIP1 expression and autophagy inhibition in CDDP-resistant EOC.

Repositioning of Antiparasitic Drugs for Tumor Treatment

“…However, drug-resistant cancer cells can survive the DNA damage induced by anticancer drugs through DNA repair pathways or bypassing cell cycle checkpoints ( 160 , 161 ); however, CQ can upregulate the expression of p21 WAF1/CIP1 to prevent this phenomenon and reverse the drug resistance of cancer cells. This function seems to depend on autophagy inhibition, but the connection is not yet clear ( 162 ). Many other functions of CQ depend on its inhibitory effect on autophagy.…”

The Intricate Interplay between Cell Cycle Regulators and Autophagy in Cancer

“…The protein p21 CIP1 can be targeted by autophagy [ 97 , 98 , 99 ]. Under various conditions, inhibition of autophagy is able to stabilize p21 CIP1 levels [ 97 , 98 , 99 ].…”

“…The protein p21 CIP1 can be targeted by autophagy [ 97 , 98 , 99 ]. Under various conditions, inhibition of autophagy is able to stabilize p21 CIP1 levels [ 97 , 98 , 99 ]. Of note, a recent study demonstrates that the ectopic expression of one of the master transcription factors of lysosomal biogenesis, TFEB, also induces p21 CIP1 expression [ 100 ].…”

Current Treatments and New Possible Complementary Therapies for Epithelial Ovarian Cancer

“…In vitro experiments have shown that chloroquine reverses cisplatin resistance in EOC cells, producing autophagy inhibition and lethal DNA damage by inducing p21WAF1/CIP1 expression [ 152 ]. Besides, autophagy inhibitors have been tested in combination with other anti-tumoral compounds.…”