Low-dose metformin suppresses hepatocellular carcinoma metastasis via the AMPK/JNK/IL-8 pathway.

BACKGROUND AND OBJECTIVES: Metformin, an oral hypoglycemic drug, has been suggested to possess antitumour activity in several types of cancers. Additionally, interleukin-8 (IL-8) has been reported to be involved in the development and metastasis of many cancers. However, the effect of metformin on IL-8 expression in hepatocellular carcinoma (HCC) remains unclear. Therefore, this study aimed to investigate whether metformin could inhibit IL-8 expression to exert an inhibitory effect on HCC progression.

MATERIALS AND METHODS: The IL-8 levels were measured in the plasma of 159 HCC patients (86 men, 73 women; average age 56 years) and in the culture supernatant of HCC cells (Hep3B and HuH7) using flow cytometry. In addition, the protein expression levels of IL-8 were also validated by the Human Protein Atlas (HPA) database. The prognostic value of IL-8 was evaluated using the Kaplan-Meier Plotter database. The association between IL-8 expression and immune checkpoints was estimated using the TIMER and The Cancer Genome Atlas (TCGA) databases. What's more, bioinformatics analysis, western blotting, and transwell assays were conducted to illustrate the molecular mechanism of metformin (≤1 mM) on IL-8 in HCC.

RESULTS: IL-8 expression was found to be increased in the plasma of HCC patients, which is consistent with the expression of IL-8 in HCC cells and tissues. High expression of IL-8 was significantly related to poor prognosis. In addition, IL-8 was positively correlated with immune checkpoints in HCC. Notably, we found that low-dose metformin could inhibit the secretion of IL-8 by HCC cells and the migration of HCC cells. Mechanistically, low-dose metformin significantly suppresses HCC metastasis mainly through the AMPK/JNK/IL-8/MMP9 pathway.

CONCLUSION: The results indicate that low-dose metformin can inhibit HCC metastasis by suppressing IL-8 expression. Targeting the AMPK/JNK/IL-8 axis may be a promising treatment strategy for patients with HCC metastasis.