Beta-Pix-dynamin 2 complex promotes colorectal cancer progression by facilitating membrane dynamics

초록

Purpose Spatiotemporal regulation of cell membrane dynamics is a major process that promotes cancer cell invasion by acting as a driving force for cell migration. Beta-Pix (beta Pix), a guanine nucleotide exchange factor for Rac1, has been reported to be involved in actin-mediated cellular processes, such as cell migration, by interacting with various proteins. As yet, however, the molecular mechanisms underlying beta Pix-mediated cancer cell invasion remain unclear. Methods The clinical significance of beta Pix was analyzed in patients with colorectal cancer (CRC) using public clinical databases. Pull-down and immunoprecipitation assays were employed to identify novel binding partners for beta Pix. Additionally, various cell biological assays including immunocytochemistry and time-lapse video microscopy were performed to assess the effects of beta Pix on CRC progression. A beta Pix-SH3 antibody delivery system was used to determine the effects of the beta Pix-Dyn2 complex in CRC cells. Results We found that the Src homology 3 (SH3) domain of beta Pix interacts with the proline-rich domain of Dynamin 2 (Dyn2), a large GTPase. The beta Pix-Dyn2 interaction promoted lamellipodia formation, along with plasma membrane localization of membrane-type 1 matrix metalloproteinase (MT1-MMP). Furthermore, we found that Src kinase-mediated phosphorylation of the tyrosine residue at position 442 of beta Pix enhanced beta Pix-Dyn2 complex formation. Disruption of the beta Pix-Dyn2 complex by beta Pix-SH3 antibodies targeting intracellular beta Pix inhibited CRC cell invasion. Conclusions Our data indicate that spatiotemporal regulation of the Src-beta Pix-Dyn2 axis is crucial for CRC cell invasion by promoting membrane dynamics and MT1-MMP recruitment into the leading edge. The development of inhibitors that disrupt the beta Pix-Dyn2 complex may be a useful therapeutic strategy for CRC.

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