JWA reverses cisplatin resistance via the CK2-XRCC1 pathway in human gastric cancer cells.

W Xu,Q Chen,Q Wang,Y Sun,S Wang,J Zhou,R Zhang,L Yang,A Li,M Wang,S Xu,O D Røe

doi:10.1038/cddis.2014.517

Abstract

Gastric cancer is the third most common malignancy in China, with a median 5-year survival of only 20%. Cisplatin has been used in first-line cancer treatment for several types of cancer including gastric cancer. However, patients are often primary resistant or develop acquired resistance resulting in relapse of the cancer and reduced survival. Recently, we demonstrated that the reduced expression of base excision repair protein XRCC1 and its upstream regulator JWA in gastric cancerous tissues correlated with a significant survival benefit of adjuvant first-line platinum-based chemotherapy as well as XRCC1 playing an important role in the DNA repair of cisplatin-resistant gastric cancer cells. In the present study, we demonstrated the role of JWA in cisplatin-induced DNA lesions and aquired cisplatin resistance in five cell-culture models: gastric epithelial cells GES-1, cisplatin-sensitive gastric cancer cell lines BGC823 and SGC7901, and the cisplatin-resistant gastric cancer cell lines BGC823/DDP and SGC7901/DDP. Our results indicated that JWA is required for DNA repair following cisplatin-induced double-strand breaks (DSBs) via XRCC1 in normal gastric epithelial cells. However, in gastric cancer cells, JWA enhanced cisplatin-induced cell death through regulation of DNA damage-induced apoptosis. The protein expression of JWA was significantly decreased in cisplatin-resistant cells and contributed to cisplatin resistance. Interestingly, as JWA upregulated XRCC1 expression in normal cells, JWA downregulated XRCC1 expression through promoting the degradation of XRCC1 in cisplatin-resistant gastric cancer cells. Furthermore, the negative regulation of JWA to XRCC1 was blocked due to the mutation of 518S/519T/523T residues of XRCC1, and indicating that the CK2 activated 518S/519T/523T phosphorylation is a key point in the regulation of JWA to XRCC1. In conclusion, we report for the first time that JWA regulated cisplatin-induced DNA damage and apoptosis through the CK2—P-XRCC1—XRCC1 pathway, indicating a putative drug target for reversing cisplatin resistance in gastric cancer.

Highlights

Gastric cancer (GC) is the fifth most common human malignant tumor worldwide but third cause of cancer death.[1]
Gastric epithelial GES-1 cells were used to study the role of ADP-ribosylation-like factor interacting protein 5 (JWA) and X-ray repair cross complementing group1 (XRCC1) in cisplatin-induced double-strand break (DSB) repair where phosphorylated histone H2AX was employed as a sensitive surrogate marker of DSBs
ΓH2AX levels increased by co-transfection of flag-JWA plasmid and XRCC1 small interfering RNA (siRNA) compared with transfected flagJWA alone (Figure 1e)

Summary

Introduction

Gastric cancer (GC) is the fifth most common human malignant tumor worldwide but third cause of cancer death.[1]. Owing to intrinsic or acquired drug resistance, relapse and metastasis are common and result in high mortality of GC.[2]. Cisplatin is a widely used chemotherapeutic drug for treating various tumors including GC.[3] Cisplatin triggers apoptosis by inducing DNA damage through crosslinking of the DNA.[4] cancer cells often develop multiple mechanisms to overcome cisplatin-induced DNA damage and apoptosis, and lead to cisplatin resistance.[5,6] Two of the major systems activated are enhanced capability of DNA repair and anti-apoptosis signaling pathways.[7,8].

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Results

Conclusion