Stress-induced upregulation of TNFSF4 in cancer-associated fibroblast facilitates chemoresistance of lung adenocarcinoma through inhibiting apoptosis of tumor cells.

Stress conditions induced by routine treatments might affect cancer-associated fibroblasts in lung adenocarcinoma. The present study tried to explore transcriptome changes in lung fibroblasts under chemotherapeutics, irradiation, and hypoxia, which were induced by chemotherapy, radiotherapy, and anti-angiogenesis therapy, respectively. We established three in vitro models to mimic the stress conditions for lung fibroblasts. Interestingly, one of the secretory molecules, tumor necrosis factor superfamily member 4 (TNFSF4, also known as OX40L), was significantly up-regulated in lung fibroblasts under stress environments. Lung adenocarcinoma patients received chemotherapy and radiotherapy had a higher expression level of TNFSF4 in serum and tumor tissues. There was a negative correlation between the increase of serum TNFSF4 levels and the shrink of the tumor after chemotherapy. TNFSF4 could promote cisplatin resistance and inhibit the apoptosis of lung adenocarcinoma cells. Furthermore, TNFSF4 could significantly increase the activity of NF-κB/BCL-XL pathway in lung adenocarcinoma cells, which could be counteracted by knocking down the expression of TNFRSF4 (receptor of TNFSF4). In conclusion, TNFSF4, secreted by cancer-associated fibroblasts under stress conditions, could facilitate chemoresistance of lung adenocarcinoma through inhibiting apoptosis of tumor cells.