Department of Pharmaceutical Sciences, West Virginia University, Morgantown, WV, USA.
Department of Pharmaceutical Sciences, West Virginia University, Morgantown, WV, USA; Siriraj Center of Excellence for Stem Cell Research, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
Lung Cancer. 2023 Jul;181:107258. doi: 10.1016/j.lungcan.2023.107258. Epub 2023 May 22.
A cure for cancer is out of reach for most patients due to chemoresistance. Cancer-associated fibroblasts (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).
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 chemoresistance was assessed using CRISPR/Cas9 knockdown and various functional assays including MTT, cell invasion, sphere formation, and cell apoptosis. In vivo experiments were conducted using a co-implantation xenograft mouse model with live cell imaging and immunohistochemistry.
We demonstrated that chemotherapy-stimulated CAFs promoted tumorigenic and stem cell-like properties 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.
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 chemotherapy response biomarker and as a drug delivery and therapeutic target for chemoresistant NSCLC.
由于化疗耐药性，大多数患者无法治愈癌症。癌症相关成纤维细胞（CAFs）在癌症化疗耐药性中起着至关重要的作用，但对其过程的详细了解，特别是在耐药性肺癌中，仍然缺乏。在这项研究中，我们研究了程序性死亡配体 1（PDL-1）作为 CAF 诱导的化疗耐药性的潜在生物标志物，并评估了其在非小细胞肺癌（NSCLC）中的作用和潜在的化疗耐药机制。
对 NSCLC 多种组织的基因表达谱进行系统搜索，以确定传统成纤维细胞生物标志物和 CAF 分泌的促肿瘤细胞因子的表达强度。通过 ELISA、Western blot 和流式细胞术分析 CAFs 中的 PDL-1 表达。使用人细胞因子阵列鉴定 CAFs 分泌的特定细胞因子。通过 CRISPR/Cas9 敲低和各种功能测定（包括 MTT、细胞侵袭、球体形成和细胞凋亡）评估 PDL-1 在 NSCLC 化疗耐药中的作用。使用活细胞成像和免疫组织化学的共植入异种移植小鼠模型进行体内实验。
我们证明了化疗刺激的 CAFs 促进了 NSCLC 细胞的致瘤和干细胞样特性，从而导致其化疗耐药性。随后，我们揭示了 PDL-1 在化疗处理的 CAFs 中表达上调，并与不良预后相关。沉默 PDL-1 表达抑制了 CAFs 促进肺癌细胞干细胞样特性和侵袭性的能力，有利于化疗耐药性。机制上，化疗处理的 CAFs 中 PDL-1 的上调导致肝细胞生长因子（HGF）分泌增加，从而刺激肺癌细胞的进展、侵袭和干细胞特性，同时抑制凋亡。
我们的结果表明，PDL-1 阳性 CAFs 通过分泌升高的 HGF 调节 NSCLC 细胞的干细胞样特性，从而促进化疗耐药性。我们的发现支持 CAFs 中的 PDL-1 作为化疗反应生物标志物以及用于治疗耐药性 NSCLC 的药物输送和治疗靶点。
