MiR-224-5p Contained in Urinary Extracellular Vesicles Regulates PD-L1 Expression by Inhibiting Cyclin D1 in Renal Cell Carcinoma Cells.

Zhiyuan Qin,Lushan Yu,Yuxi Liu,Wen Sun,Qingwen Xu,Shengnan Jin,Su Zeng,Haihong Hu,Lu Chen

doi:10.3390/cancers13040618

Abstract

Simple SummaryThe detailed effects of abundant microRNAs contained in extracellular vesicles (EVs) on renal cell carcinoma (RCC) progression are still unclear. This study identified the overexpression of miR-224-5p in urinary EVs of RCC patients. miR-224-5p suppressed RCC cell proliferation and induced cell cycle arrest through inhibiting cyclin D1 expression. PD-L1 protein abundance was increased by miR-224-5p, and this regulation could be transmitted via EVs intercellularly. These findings may shed light on biomarker discovery for RCC immunotherapy.The abundant miRNAs in urinary extracellular vesicles (EVs) represent ideal reservoirs for biomarker discovery, especially in renal cell carcinoma (RCC). However, the content and biological functions of microRNAs contained in urinary EVs in RCC remain ambiguous. In this study, urinary EVs were isolated and characterized from RCC patients and healthy volunteers. Differentially expressed microRNAs in urinary EVs were screened by small RNA sequencing. The target gene and biological functions of selected microRNAs were investigated through multifaceted methods. Results indicated that miR-224-5p was significantly upregulated in urinary EVs of RCC patients compared to healthy volunteers. The overexpression of miR-224-5p inhibited RCC cell proliferation and induced cell cycle arrest. The gene CCND1 encoding cyclin D1 was identified as a direct target of miR-224-5p via prediction and validation. Moreover, the invasive and metastatic abilities of RCC cells were enhanced by miR-224-5p. Interestingly, miR-224-5p also increased the stability of PD-L1 protein by inhibiting CCND1. This effect could be transmitted via EVs and further promoted the resistance of RCC cells to T cell-dependent toxicity. In summary, urinary EVs containing miR-224-5p were identified as a potential biomarker in RCC. Regulation of PD-L1 protein expression by miR-224-5p through suppressing CCND1 elucidates new roles of miR-224-5p in RCC progression.

Highlights

Renal cell carcinoma (RCC) is among the most common urological cancers, accounting for approximately 90% of all kidney cancer cases [1]
To characterize the shape and size distribution of extracellular vesicles (EVs), EVs were examined by transmission electron microscopy (TEM) and nanoparticle tracking analysis (NTA), respectively
The results suggested that more RCC cells were alive after transfection of miR-224-5p mimics compared to NC, and this effect could be reversed by miR-224-5p inhibitors (Figure 8B)

Summary

Introduction

Renal cell carcinoma (RCC) is among the most common urological cancers, accounting for approximately 90% of all kidney cancer cases [1]. Owing to advances in early diagnosis techniques and targeted therapies, the five-year survival rate of RCC patients has improved in recent years. It is estimated that approximately one-third of patients with RCC are diagnosed with metastases, which typically require systemic treatments targeting tumor signaling pathways or the immune system [2]. One of the immunotherapies that target immune checkpoints, represented by blockade of programmed cell death protein 1. (PD-1) and its ligand programmed death ligand 1 (PD-L1), has been approved for clinical treatment of RCC patients [3]. The response rate of PD1/PD-L1 inhibitors in RCC is relatively low [4]. It is necessary to identify relevant PD-1/PD-L1 biomarkers to predict treatment responses

Methods

Results

Conclusion