HIF-1α is necessary for activation and tumour-promotion effect of cancer-associated fibroblasts in lung cancer.

Cancer-associated fibroblasts (CAFs) activation is crucial for the establishment of a tumour promoting microenvironment, but our understanding of CAFs activation is still limited. In this study, we found that hypoxia-inducible factor-1α (HIF-1α) was highly expressed in CAFs of human lung cancer tissues and mouse spontaneous lung tumour. Accordingly, enhancing the expression of HIF-1α in fibroblasts via hypoxia induced the conversion of normal fibroblasts into CAFs. HIF-1α-specific inhibitor or HIF-1α knockout (KO) significantly attenuated CAFs activation, which was manifested by the decreased expression of COL1A2 and α-SMA. In vivo, during tumour formation, the expression of Ki-67 and proliferating cell nuclear antigen (PCNA) in the tumour tissue with HIF-1α KO fibroblasts was significantly lower than that of normal fibroblasts. Moreover, HIF-1α in fibroblasts could activate the NF-κB signalling pathway and enhance a subsequent secretion of CCL5, thus promoting the tumour growth. In conclusion, our results suggest that HIF-1α is essential for the activation and tumour-promotion function of CAFs in lung cancer (LC). And targeting HIF-1α expression on CAFs may be a promising strategy for LC therapy.