The role and molecular mechanism of GDF5 in regulating cell migration and angiogenesis via the Hippo-YAP signaling pathway in colorectal cancer.

292 Background: Distant metastasis is a leading cause of poor prognosis and mortality in colorectal cancer (CRC) patients, with angiogenesis playing a crucial role in tumor progression. The TGF-β superfamily has been shown to significantly influence tumor angiogenesis, yet the biological function and molecular mechanism of Growth Differentiation Factor 5 (GDF5), a member of this superfamily, remain unexplored in CRC. Given that the efficacy of current anti-angiogenic therapies is limited to a subset of patients, identifying new therapeutic targets involved in tumor angiogenesis is of great clinical importance. GDF5, with its potential role in angiogenesis regulation, presents a promising candidate to bridge this therapeutic gap. Methods: In this study, we analyzed GDF5 expression in CRC tissue samples using both the TCGA dataset and samples from our center, revealing significantly lower GDF5 expression in tumors compared to adjacent normal tissues. Moreover, GDF5 downregulation correlated with lymph node metastasis and disease recurrence. Functional assays in vitro demonstrated that GDF5 overexpression reduced tumor cell migration and invasion, while its knockdown produced the opposite effect. Co-culture assays showed that GDF5 knockdown significantly enhanced endothelial cell migration and angiogenesis, whereas overexpression diminished these effects. Additionally, F-actin cytoskeletal staining indicated that GDF5 overexpression led to cytoskeletal remodeling in endothelial cells. Mechanistically, we found that GDF5 overexpression in tumor cells downregulated the epithelial-mesenchymal transition (EMT) marker Slug and upregulated E-cadherin, while downregulating N-cadherin. In endothelial cells, GDF5 inhibited the Hippo-YAP signaling pathway, increasing YAP phosphorylation and reducing nuclear YAP levels. Conversely, GDF5 knockdown suppressed YAP phosphorylation and promoted its nuclear translocation. Results: Our findings demonstrate that GDF5 functions as a tumor suppressor in CRC by regulating cell migration and angiogenesis. This study reveals that GDF5 exerts its anti-cancer effects by modulating both EMT in tumor cells and cytoskeletal changes in endothelial cells, leading to the inhibition of the Hippo-YAP signaling pathway and reduced angiogenic potential. These results identify GDF5 as a promising new target for anti-angiogenic therapy in CRC, offering potential avenues for improving treatment strategies in patients resistant to current therapies. Conclusions: GDF5 acts as a tumor suppressor in colorectal cancer by inhibiting cell migration and angiogenesis through modulation of the Hippo-YAP signaling pathway, making it a promising therapeutic target for anti-angiogenic treatment in patients resistant to current therapies.