No abstract

Cisplatin is the major chemotherapeutic drug in gastric cancer, particularly in treating advanced gastric cancer. Tumour cells often develop resistance to chemotherapeutic drugs, which seriously affects the efficacy of chemotherapy. GPR30 is a novel oestrogen receptor that is involved in the invasion, metastasis and drug resistance of many tumours. Targeting GPR30 has been shown to increase the drug sensitivity of breast cancer cells. However, few studies have investigated the role of GPR30 in gastric cancer. Epithelial‐mesenchymal transition (EMT) has been shown to be associated with the development of chemotherapeutic drug resistance. In this study, we demonstrated that GPR30 is involved in cisplatin resistance by promoting EMT in gastric cancer. GPR30 knockdown resulted in increased sensitivity of different gastric cancer (GC) cells to cisplatin and alterations in the epithelial/mesenchymal markers. Furthermore, G15 significantly enhanced the cisplatin sensitivity of GC cells while G1 inhibited this phenomenon. In addition, EMT occurred when AGS and BGC‐823 were treated with cisplatin. Down‐regulation of GPR30 with G15 inhibited this transformation, while G1 promoted it. Taken together, these results revealed the role of GPR30 in the formation of cisplatin resistance, suggesting that targeting GPR30 signalling may be a potential strategy for improving the efficacy of chemotherapy in gastric cancer.

Background and aim: Paclitaxel (PTX) plus 5-fluorouracil (5-Fu) has become the standard chemotherapy for advanced gastric cancer (GC). Apatinib, a small-molecule tyrosine kinase inhibitor targeting vascular endothelial growth factor receptor-2, improves outcomes in GC patients as a third-line treatment. However, its impact on the chemosensitivity of GC remains to be determined. Hence, we aimed to assess the efficacy and safety of apatinib combined with chemotherapy in vivo and in vitro. Methods: The MGC803 cell viability was determined by Cell Counting Kit-8 assay, and the interactions between apatinib and conventional cytotoxic agents revealed by combination index values were calculated using Calcusyn 2.0 software. We also used a zebrafish embryo xenograft model to validate the synergistic interactions. Furthermore, 4 patients with late-stage GC were enrolled to explore the efficacy and safety of PTX/Tegafur Gimeracil Oteracil Potassium (S1) (PS) chemotherapy plus apatinib in conversion surgery. Results: Apatinib showed synergistic interactions with both PTX and 5-Fu in vivo. The zebrafish embryo xenograft model also demonstrated that apatinib significantly enhanced the antitumor activity of PTX and 5-Fu. Apatinib plus PS chemotherapy was well tolerated before surgery. Objective response to preoperative SPA treatment was achieved in all 4 patients. No postoperative bleeding events or wound-healing complications were observed. No postperative morbidity occurred and no morbidity was encountered. Pathological examination showed that all patients had grade Ib pathological response. Conclusion: The experimental data suggested that apatinib improves the efficacy of PTX and 5-Fu both in vitro and in vivo. Clinical evidence showed that a combination of PS chemotherapy with apatinib may be an efficient and acceptable safety treatment for late-stage GC, especially in conversion surgery.