Identification and Validation of programmed cell death-related biomarkers in Osteoarthritis and an Exploratory...

This study aimed to identify programmed cell death (PCD)-related hub genes in osteoarthritis (OA) and to explore their potential diagnostic value. Given the shared biological pathways between OA and cancer, an exploratory pan-cancer analysis was also conducted to investigate the potential links.

We integrated OA patient information from two GEO databases for differential gene expression (DEGs) analysis. OA-related module genes were selected by weighted gene co-expression network analysis (WGCNA). Programmed cell death (PCD)-related genes were extracted from a previous study. The module genes related to DEGs, WGCNA and PCD were overlapped. After using LASSO algorithms to analyze these key genes and take the intersection, we constructed an OA diagnostic model based on the six identified hub genes (SHARPIN, FLCN, PIK3R2, TBK1, VPS33A and ZMYND11). The diagnostic model's performance was evaluated, and further gene correlation, immune infiltration, and functional pathway analyses were performed. We exploratorily investigated the potential carcinogenesis of hub genes, including dissecting the correlation of prognosis, immune cell infiltration, and immune checkpoint-related genes. For this exploratory analysis, we obtained pan-cancer-related genes from the TCGA and GTEx databases. Finally, the expression of hub genes was further verified by immunofluorescence (IF) in OA patients.

The results indicate a significant up-regulation of SHARPIN, FLCN, PIK3R2 and VPS33A in OA synovial tissues, while TBK1 and ZMYND11 exhibit a significant down-regulation. SHARPIN exhibited a notably significant increase in expression, prompting its selection for further experiments. The expression level of SHARPIN mRNA was significantly changed in IL-1β-induced rat synovial fibroblasts (SFs) in an in vitro qPCR experiment. Knockdown of SHARPIN reduced the expression of ADAMTS-5, MMP3, MMP13, and altered Bcl2 and Bax expression in IL-1β-stimulated SFs.

These findings suggest that SHARPIN may be a potential diagnostic biomarker and intervention target for OA. The exploratory pan-cancer analysis revealed correlative associations that warrant further investigation but does not establish a definitive link between OA and cancer. Keypoints • SHARPIN, FLCN, PIK3R2, TBK1, VPS33A, and ZMYND11 were identified as hub genes associated with programmed cell death in osteoarthritis. •The six-gene diagnostic model demonstrated high accuracy in distinguishing OA patients from controls, supporting its potential as a biomarker panel. • SHARPIN was significantly upregulated in OA synovial tissues, and its knockdown reversed the expression of ADAMTS-5, MMP3, MMP13, Bcl2, and Bax in IL-1β stimulated synovial fibroblasts. • Targeting SHARPIN may represent a novel diagnostic or therapeutic strategy to modulate inflammation and joint destruction in osteoarthritis.