Matricellular proteins are a subset of extracellular matrix (ECM) proteins which are dynamically expressed and serve many regulatory roles. Among matricellular proteins, the CCN family, a group of secreted proteins are known to regulate cell adhesion, migration, proliferation, differentiation, apoptosis, survival, senescence, and gene expression. Connective tissue growth factor (CTGF), also known as CCN2, is a member of the CCN family. CTGF is known to have many roles in biological processes such as cell proliferation, migration, adhesion, and angiogenesis.
To investigate the function of CTGF in triple-negative breast cancer cells (TNBC), we silenced CTGF in TNBC cell lines using short hairpin RNA. Knockdown of CTGF was verified by western blot, qPCR, and immunostaining. The effect of CTGF knockdown on TNBCs was examined by cell proliferation assay, adhesion assay, migration assays, metabolism assays, and cell cycle analysis.
Knockdown of CTGF decreased cell proliferation, adhesion, migration, glucose uptake, ATP production and lactate production. Since CTGF is a secreted protein, we gave recombinant human CTGF (rhCTGF) to the cells and found that rhCTGF induced activation of the Src/FAK/MAPK pathway and led to expression of proteins related to cell cycle progression. Also, when CTGF-specific antibodies were given to the cells, they expressed cytotoxicity by neutralizing the extracellular CTGF and decreasing CTGF-mediated signalling.
We suggest that the secreted CTGF mediates tumor cell progression via modulation of cell proliferation, adhesion, migration and metabolism and could possess a potential for being a therapeutic target.
National Research Foundation of Korea.
All authors have declared no conflicts of interest.