Department of Life Science, Chung-Ang University, Seoul, 06974, Republic of Korea.
Translational Research Program, Benaroya Research Institute at Virginia Mason, Seattle, WA, 98101, USA.
Cell Oncol (Dordr). 2021 Dec;44(6):1287-1305. doi: 10.1007/s13402-021-00637-6. Epub 2021 Sep 28.
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 (βPix), 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 βPix-mediated cancer cell invasion remain unclear.
The clinical significance of βPix 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 βPix. Additionally, various cell biological assays including immunocytochemistry and time-lapse video microscopy were performed to assess the effects of βPix on CRC progression. A βPix-SH3 antibody delivery system was used to determine the effects of the βPix-Dyn2 complex in CRC cells.
We found that the Src homology 3 (SH3) domain of βPix interacts with the proline-rich domain of Dynamin 2 (Dyn2), a large GTPase. The βPix-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 βPix enhanced βPix-Dyn2 complex formation. Disruption of the βPix-Dyn2 complex by βPix-SH3 antibodies targeting intracellular βPix inhibited CRC cell invasion.
Our data indicate that spatiotemporal regulation of the Src-βPix-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 βPix-Dyn2 complex may be a useful therapeutic strategy for CRC.
细胞膜动力学的时空调节是促进癌细胞侵袭的主要过程，它作为细胞迁移的驱动力发挥作用。β-Pix（βPix）是 Rac1 的鸟嘌呤核苷酸交换因子，据报道通过与各种蛋白质相互作用参与细胞运动等肌动蛋白介导的细胞过程。然而，βPix 介导的癌细胞侵袭的分子机制尚不清楚。
使用公共临床数据库分析结直肠癌（CRC）患者中βPix 的临床意义。采用下拉和免疫沉淀实验鉴定βPix 的新结合伴侣。此外，还进行了各种细胞生物学实验，包括免疫细胞化学和延时视频显微镜检查，以评估βPix 对 CRC 进展的影响。使用βPix-SH3 抗体传递系统来确定βPix-Dyn2 复合物在 CRC 细胞中的作用。
我们发现βPix 的Src 同源结构域 3（SH3）与动力蛋白 2（Dyn2）的富含脯氨酸结构域相互作用，Dyn2 是一种大型 GTPase。βPix-Dyn2 相互作用促进了片状伪足的形成，以及膜型 1 基质金属蛋白酶（MT1-MMP）的质膜定位。此外，我们发现Src 激酶介导的βPix 位置 442 酪氨酸残基磷酸化增强了βPix-Dyn2 复合物的形成。针对细胞内βPix 的βPix-SH3 抗体破坏βPix-Dyn2 复合物抑制了 CRC 细胞侵袭。
我们的数据表明，Src-βPix-Dyn2 轴的时空调节通过促进膜动力学和 MT1-MMP 募集到前缘对于 CRC 细胞侵袭至关重要。开发破坏βPix-Dyn2 复合物的抑制剂可能是 CRC 的一种有用的治疗策略。
