Hypoxia-induced MIF induces dysregulation of lipid metabolism in Hep2 laryngocarcinoma through the IL-6/JAK-STAT pathway.

PURPOSE

Hypoxia is a common feature of laryngocarcinoma. Alterations in lipid metabolism are an important metabolic rewiring phenomenon for malignant cells to maintain their rapid proliferation in the hypoxic microenvironment, which makes most cancers, including laryngocarcinoma, difficult to cure. However, the mechanisms involved in lipid metabolism in laryngocarcinoma is still unclear. This study aimed to clarify the changes in lipid metabolism of laryngocarcinoma cells under hypoxic conditions and explore the related mechanisms.

METHODS

Hep2 cells were incubated in a normoxic or hypoxic environment (5% CO and 1% O) at 37 °C for 24 h. CCK-8 cell viability assay and colony formation assay were performed to detect cells proliferation. And lipid metabolic indices including TG and NEFA were determined by kits. The mechanism involved in the regulation of lipid metabolism was explored by RNA-seq and bioinformatic analysis. The MIF inhibitor ISO-1 and JAK inhibitor XL019 were used to verify the mechanism. Finally, a tumour xenograft model was applied to further verify these results in vivo.

RESULTS

Hypoxia promoted cell proliferation and increased the levels of TG and NEFA in Hep2 cells. Three genes, MIF, ENO2, and LDHA, that were screened by the intersection of hypoxia gene sets and fatty gene sets and were verified by qPCR. The MIF levels were elevated when cells were exposed to hypoxia. Through GSEA and RNA-seq analysis, the JAK/STAT pathway was screened. Hypoxia increased MIF levels and activated the IL-6/JAK/STAT pathway. The MIF inhibitor ISO-1inhibited cell proliferation under hypoxia and reversed the change in TG levels and IL-6 levels. And ISO-1 reversed the expression pattern of the screened genes in the JAK/STAT pathway. Finally, a tumour xenograft model further verified these results in vivo.

CONCLUSION

Hypoxia induced reprogramming of lipid metabolism in laryngocarcinoma cells through the MIF/IL-6/JAK-STAT pathway. This study revealed one mechanism that allows laryngocarcinoma cells to adapt to the hypoxic tumour microenvironment. Therefore, a drug targeting the MIF/IL-6/JAK-STAT pathway might be a promising therapeutic option for the treatment of laryngocarcinoma.