Silencing of Growth Differentiation Factor-15 Promotes Breast Cancer Cell Invasion by Down-regulating Focal Adhesion Genes

Background/aim: As metastasis accounts for most breast cancer (BC)-related deaths, identifying key players becomes research priority. Growth differentiation factor-15 (GDF15), a member of the transforming growth factor-beta superfamily, is affected by the actin cytoskeleton and has been associated with cancer. However, its exact role in BC cell invasiveness is vague. Materials and Methods: GDF15 shorthairpin (shRNA)-mediated silencing was used to inhibit GDF15 expression in MCF-7 and MDA-MB-231 BC cells and gene expression of relevant focal adhesion (FA) genes, cell migration, invasion and tumor spheroid invasion were subsequently analyzed. Results: GDF15 silencing promoted cell migration, cell invasion as well as tumor spheroid invasion and up-regulated urokinase plasminogen activator (uPA) and FA genes, integrin-linked kinase (ILK), LIM zinc finger domain containing 1 (LIMS1), alpha-parvin (PARVA), and RAS suppressor-1 (RSU1). Computational analysis of Cancer Genome Atlas BC dataset however, revealed no significant correlation between GDF15 expression and metastasis pointing towards a more complex molecular interplay between GDF15, actin cytoskeleton and FA-related genes which ultimately affects their expression pattern, in vivo. Conclusion: GDF15 suppresses BC cell invasion in vitro through down-regulation of FA genes but its role in BC is more complicated in vivo and warrants further investigation.