OncoTargets and Therapy (May 2020)
Inhibition of Serine Metabolism Promotes Resistance to Cisplatin in Gastric Cancer
Abstract
Xiaoya Zhao,1,2,* Jianfei Fu,3,* Wanfen Tang,3 Liangliang Yu,4 Wenxia Xu1 1Central Laboratory, Jinhua Hospital of Zhejiang University, Jinhua 321000, Zhejiang Province, People’s Republic of China; 2Department of Medical Oncology, Sir Run Run Shaw Hospital, Medical School of Zhejiang University, Hangzhou 310000, Zhejiang Province, People’s Republic of China; 3Department of Medical Oncology, Jinhua Hospital of Zhejiang University, Jinhua 321000, Zhejiang Province, People’s Republic of China; 4Department of Gastroenterology, Sir Run Run Shaw Hospital, Medical School of Zhejiang University, Hangzhou 310000, Zhejiang Province, People’s Republic of China*These authors contributed equally to this workCorrespondence: Liangliang YuDepartment of Gastroenterology, Sir Run Run Shaw Hospital, Medical School of Zhejiang University, No. 3 Qingchun Road, Jianggan District, Hangzhou 310000, Zhejiang Province, People’s Republic of ChinaTel +86 571-86006646Email [email protected] XuCentral Laboratory, Jinhua Hospital of Zhejiang University, No. 351 Mingyue Street, Wucheng District, Jinhua 321000, Zhejiang Province, People’s Republic of ChinaTel +86 579 82553851Email [email protected]: Serine provides important precursors of protein, lipid, and nucleotide synthesis needed for tumor cell growth. Phosphoglycerate dehydrogenase (PHGDH), a key rate-limiting enzyme in the serine de novo synthesis pathway, is highly expressed in many tumor types (including gastric cancer) and negatively correlated with overall survival. Cisplatin is a chemotherapeutic drug commonly used in the treatment of gastric cancer. In this study, we mainly investigated the relationship between serine metabolism and resistance to cisplatin in gastric cancer cells, as well as the regulatory mechanism involved in this process.Materials and Methods: We determined the effect of different concentrations of serine or a PHGDH inhibitor combined with cisplatin or oxaliplatin on the viability and apoptosis of SGC7901, BGC823, and MGC803 cells via the Cell Counting Kit-8 and Hoechst 33258 staining, respectively. Western blotting was utilized to detect the relative protein expression. Furthermore, we investigated DNA damage through the micrococcal nuclease sensitivity assay detected using agarose gels.Results: We found that reduced concentrations of serine or inhibition of PHGDH hindered the toxicity and pro-apoptotic effects of cisplatin on gastric cancer cells. Moreover, the addition of serine could reverse the sensitivity of gastric cancer cells to cisplatin. Moreover, we found that DNA damage was reduced by treatment with PHGDH inhibitor NCT-503 or CBR-5884. Inhibition of serine metabolism induced a decrease in H3K4 tri-methylation, which was reversed by JIB-04 (inhibitor of H3K4 demethylase). The tolerance of gastric cancer cells to cisplatin was relieved by JIB-04. Through micrococcal nuclease experiments, we further found that inhibiting the activity of PHGDH strengthened chromatin tightness.Conclusion: Inhibition of serine metabolism reduced H3K4 tri-methylation and increased the density of chromatin, which leads to decreased toxicity and pro-apoptotic effect of platinum chemotherapeutic drugs on gastric cancer cells.Keywords: serine metabolism, cisplatin resistance, PHGDH, DNA damage, gastric cancer
