Identification of WISP1 as an important survival factor in human mesenchymal stem cells

WNT-induced secreted protein 1 (WISP1/CCN4), a member of the CCN protein family, acts as a downstream factor of the canonical WNT-signaling pathway. A dysregulated expression of WISP1 often reflects its oncogenic potential by inhibition of apoptosis, a necessary form of cell death that protect cell populations for transformation into malignant phenotypes. WISP1-signaling is also known to affect proliferation and differentiation of human mesenchymal stem cells (hMSCs), which are fundamental for the constitution and maintenance of the musculoskeletal system. Our study emphasizes the importance of WISP1-signaling for cell survival of primary human cells. Therefore, we established a successful down-regulation of endogenous WISP1 transcripts through gene silencing in hMSCs. We were able to demonstrate the consequence of cell death immediately after WISP1 down-regulation took place. Bioinformatical analyses of subsequent performed microarrays from WISP1 down-regulated vs. control samples confirmed this observation. We uncovered several clusters of differential expressed genes important for cellular apoptosis induction and immuno-regulatory processes, thereby indicating TRAIL-induced and p53-mediated apoptosis as well as IFNbeta-signaling. Since all of them act as potent inhibitors for malignant cell growth, in vitro knowledge about the connection with WISP1-signaling could help to find new therapeutic approaches concerning cancerogenesis and tumor growth in musculoskeletal tissues. We established a successful down-regulation of endogenous WISP1 transcripts through gene silencing in hMSCs. Knock-down versus controls.