Palmitic Acid Inhibits the Growth and Metastasis of Gastric Cancer by Blocking the STAT3 Signaling Pathway

SIMPLE SUMMARY: In this study, we investigated the effects of palmitic acid (PA) on multiple human gastric cancer cell lines and combined them with the results from clinical gastric cancer and paracancerous tissue samples. Our findings demonstrated that PA exerted anti-gastric cancer effects by regulating key molecules in the signal transduction and activation of a transcription 3 (STAT3) protein inhibitor of the activated STAT 3 (PIAS3) signaling pathway. Our results serve as a foundation for further research on the correlation between the anti-gastric cancer activity of PA and the STAT3-PIAS3 signaling pathway. Our results also represent a critical step toward understanding gastric cancer prevention and prognosis and promoting PA supplementation as a gastric cancer treatment. ABSTRACT: Lipidomic analyses have suggested that palmitic acid (PA) is linked to gastric cancer. However, its effects and action mechanisms remain unclear. Therefore, we evaluated the effects of PA on cell proliferation, invasion, and apoptosis in human gastric cancer, as well as the role of p-STAT3 in mediating its effects. The results of the MTT and colony formation assays revealed that PA blocked gastric cancer cell proliferation in a concentration-dependent manner. The EdU-DNA assay indicated that 50 μM of PA could block gastric cell proliferation by 30.6–80.0%. The Transwell assay also confirmed the concentration dependence of PA-induced inhibitory effect on cell invasion. The flow cytometry analysis indicated that PA treatment for 18 h could induce gastric cancer cell apoptosis. The immunohistochemical staining revealed that p-STAT3 levels were higher in the gastric cancer tissues than in the control tissues. We demonstrated that PA treatment for 12 h decreased the expressions of p-STAT3, p-JAK2, N-cadherin, and vimentin, and inhibited the nuclear expression of p-STAT3 in gastric cancer cells. Finally, PA treatment (50 mg/kg) decreased gastric cancer growth (54.3%) in the xenograft models. Collectively, these findings demonstrate that PA inhibits cell proliferation and invasion and induces human gastric cancer cell apoptosis.