MiR-140 Expression Regulates Cell Proliferation and Targets PD-L1 in NSCLC

Abstract

Background/Aims: Programmed death ligand1(PD-L1) plays a role in the development and progression of non-small cell lung cancer (NSCLC). This study aimed to identify miRNA(s) that are responsible for regulation of expression of PD-L1 in NSCLC, and to investigate the role of PD-L1 in regulation of the cell cycle in NSCLC. Methods: We predicted the target miRNA of PD-L1, which was miR-140, using the online tools TargetScan and miBase. In NSCLC cells obtained from clinical specimens, in addition to A549 and NCI-H1650 cell cultures, western blots were used to detect the level of expression of proteins, while real-time PCR was used to determine the level of expression of PD-L1, miR-140, cyclin E, and β-actin. Transfection with miR-140 mimics, miR-140 inhibitors, and PD-L1 siRNA were conducted using commercial kits. To determine whether miR-140 directly binds PD-L1, a luciferase reporter gene with wild type or mutated PD-L1 was used. Cell viability was measured with the MTT assay, and PI staining was used for cell cycle analysis. Results: We found low expression of miR-140 and high expression of PD-L1 and cyclin E in NSCLC cells. Over-expression of miR-140 suppressed the expression of PD-L1 by directly binding its 3’ UTR, and was also associated with decreased expression of cyclin E and inhibition of cellular proliferation in A549 and NCI-H1650 cells. Inhibition of PD-L1, in the absence of manipulations to miR-140, also decreased the expression of cyclin E. Conclusion: We conclude that miR-140 directly suppresses PD-L1 and inhibits the miR-140/PD-L1/cyclin E pathway in NSCLC.

MicroRNAs aid the assessment of programmed death ligand�1 expression in patients with non‑small cell lung cancer

“…These molecules act by either promoting mRNA degradation or inhibiting translation (15,16). There are few reports concerning the regulation of PD-L1 expression by miRs in lung cancer (17)(18)(19). Therefore, the purpose of the present study was to assess the expression of miRs with the ability to regulate PD-L1 expression in patients with NSCLC, and to determine the association between these factors and the expression of PD-L1 mRNA and protein in tumor cells.…”

Roles of circRNAs in the tumour microenvironment

“…Currently, drugs targeting PD-L1 are being tested in clinical trials against multiple cancer types, including colorectal cancer (CRC) [83], nonsmall cell lung cancer (NSCLC) [84,85], and urothelial carcinoma [86]. In the past few decades, the roles of miR-NAs in regulating the expression of the PD-1/PD-L1 immune checkpoint and the sensitivity of tumours to chemotherapy drugs have been well studied [87,88], revealing that circRNAs contribute to immune escape through a circRNA-miRNA-PD-1/PD-L1 axis (Fig. 1c).…”

Non-Coding RNAs in Lung Tumor Initiation and Progression

“…Chen et al found that miR-200/ZEB1 axis regulates PD-L1 expression and has a strong correlation with EMT tumors [180]. Another miRNA that binds and inhibits PD-L1 is miR-140 [111]. miR-140 is downregulated in NSCLC, leading to increased expression of PD-L1, which can increase the expression of cyclin E [111], a gene that dysregulates G1-S transition and the S phase in lung tumors to increase their proliferation [181].…”

“…Another miRNA that binds and inhibits PD-L1 is miR-140 [111]. miR-140 is downregulated in NSCLC, leading to increased expression of PD-L1, which can increase the expression of cyclin E [111], a gene that dysregulates G1-S transition and the S phase in lung tumors to increase their proliferation [181]. Other reported PD-L1 regulators include miR-197 through the miR-197/CKS1B/STAT3 signaling pathway [182] and an inverse relationship with miR-33a [183].…”