Tissue Inhibitors of Metalloproteinases 1 Confers 5-Fluorouracil Resistance and Stemness of Gastric Cancer Cells via the Up-Regulation of Hypoxia-Inducible Factor-1α

The role and potential mechanism of TIMP1 in resistance to 5-Fluorouracil (5-Fu) and stem properties in gastric cancer (GC) were investigated. The expressions of HIF-1α and TIMP1, as well as the chemosensitivity of the 5-Fu in GC cell lines (GCCL) (e.g., MGC-803, BGC-823, SGC-7901, HGC-27 and AGS) upon normoxia or hypoxia were analyzed by means of RT-PCR and CCK-8 assay, respectively. Meanwhile, the population of stem cells was determined by using sphere formation assay, while stem cell markers (SCM) (Oct4 and CD44) were detected by western blot to evaluate stem properties. Hypoxia led to upregulated expression of HIF-1α and TIMP1, and enhanced resistance to 5-Fu, sphere formation capability, and expression of SCM in GC cells (GCCs). Indeed, the expressions of TIMP1 and HIF-1α were positively related to each other. The protein levels of both HIF-1α and TIMP1 were increased and decreased by overexpressing and silencing TIMP1, respectively. Under hypoxia conditions, overexpression of TIMP1 conferred 5-Fu-resistance and stem properties to MGC-803 and AGS cells, as revealed by increased IC50 value of 5-Fu, enhanced sphere formation, and up-regulation of Oct4 and CD44; silencing TIMP1 caused the contrary results. TIMP1 is an effective regulator of HIF-1 and plays a critical role in resistance to 5-Fu and stem properties in GCCs upon hypoxia.