Chemotherapy-induced PDL-1 expression in cancer-associated fibroblasts promotes chemoresistance in NSCLC

Objectives: A cure for cancer is out of reach for most patients due to chemoresistance. Cancer-associated fibro-blasts (CAFs) play a vital role in cancer chemoresistance, but detailed understanding of the process particularly in chemoresistant lung cancer is lacking. In this study, we investigated programmed death-ligand 1 (PDL-1) as a potential biomarker for CAF-induced chemoresistance and evaluated its role and the underlying mechanisms of chemoresistance in non-small cell lung cancer (NSCLC).Materials and Methods: A systemic search of gene expression profiles of multiple tissues in NSCLC was carried out to determine the expression intensities of traditional fibroblast biomarkers and CAF-secreted protumorigenic cytokines. PDL-1 expression in CAFs was analyzed by ELISA, Western blotting, and flow cytometry. Human cytokine array was used to identify specific cytokines secreted from CAFs. Role of PDL-1 in NSCLC chemo-resistance was assessed using CRISPR/Cas9 knockdown and various functional assays including MTT, cell in-vasion, sphere formation, and cell apoptosis. In vivo experiments were conducted using a co-implantation xenograft mouse model with live cell imaging and immunohistochemistry.Results: We demonstrated that chemotherapy-stimulated CAFs promoted tumorigenic and stem cell-like prop-erties of NSCLC cells, which contribute to their chemoresistance. Subsequently, we revealed that PDL-1 expression is upregulated in chemotherapy-treated CAFs and is associated with poor prognosis. Silencing PDL-1 expression suppressed CAFs' ability to promote stem cell-like properties and invasiveness of lung cancer cells, favoring chemoresistance. Mechanistically, an upregulation of PDL-1 in chemotherapy-treated CAFs led to an increase in hepatocyte growth factor (HGF) secretion, which stimulates cancer progression, cell invasion, and stemness of lung cancer cells, while inhibiting apoptosis.Conclusion: Our results show that PDL-1-positive CAFs modulate stem cell-like properties of NSCLC cells by secreting elevated HGF, thereby promoting chemoresistance. Our finding supports PDL-1 in CAFs as a chemo-therapy response biomarker and as a drug delivery and therapeutic target for chemoresistant NSCLC.

Automated summary

This study investigated the potential biomarker programmed death-ligand 1 (PDL-1) for cancer-associated fibroblasts (CAFs)-induced chemoresistance in non-small cell lung cancer (NSCLC). The results showed that chemotherapy-stimulated CAFs promote tumorigenic and stem cell-like properties of NSCLC cells, leading to chemoresistance. Upregulation of PDL-1 expression in chemotherapy-treated CAFs is associated with poor prognosis, and silencing PDL-1 expression suppresses CAFs' ability to promote stem cell-like properties and invasiveness of lung cancer cells, favoring chemoresistance.