Mapping and analysis of protein and gene profiles identify the important role of TGF-β in synovial invasion in pigmented villonodular synovitis.

Abstract

Pigmented villonodular synovitis (PVNS) is a rare benign proliferative disease affecting the soft tissue lining the synovial joints and tendons. Its etiology is poorly understood, largely limiting the availability of current therapeutic options. Here, we mapped the synovial gene and protein profiles of patients with PVNS, revealed a link between synovial inflammation and invasion, and elucidated the potential molecular mechanism involved. The expression of synovial genes from six control individuals, seven OA patients, and nineteen PVNS patients was analyzed via RNA sequencing. Protein profiles from five control individuals, ten OA patients, and thirty-two PVNS patients were analyzed using label-free proteomics. Microarray and RT-PCR analyses and immunohistochemical staining were used to evaluate inflammatory cytokine and target gene expression levels in synovial tissue, epithelial cells, and synovial fibroblasts (FLSs) derived from PVNS tissue. Various signaling pathway inhibitors, siRNAs, and western blots were used for molecular mechanism studies. Transwell migration and invasion assays were subsequently performed. In total, 522 differentially expressed proteins were identified in the PVNS tissues. By integrating RNA sequencing and microarray analyses, significant changes in the expression of EMT-related genes, including TGFBI, N-cadherin, E-cadherin, SNAIL, and TWIST, were confirmed in the PVNS tissue compared to the control tissue. In vitro, TGF-β induced EMT and increased epithelial cell migration and invasion. Moreover, TGF-β not only promoted interactions between epithelial cells and FLSs but also directly increased the migration and invasion abilities of FLSs by activating the classical Smad2/3 and nonclassical JNK/AKT signaling pathways. This study provides overall protein and gene profiles of PVNS and identifies the crucial role of TGF-β in synovial invasion pathology. Exploring the related molecular mechanism may also reveal a new strategy or target for PVNS therapy.