钙离子通道CACNA1B通过调控伪足延伸促进乳腺癌转移的机制研究

Ion channels have been implicated in multiple neurological diseases, but much less is known regarding their roles in cancer. Using bioinformatic analysis of breast cancer genomics data, we recently discovered that high expression of an ion channel protein is significantly inversely correlated with breast cancer survival. Specifically, we found that high expression of the calcium channel CACNA1B is predictive of poor prognosis. In preliminary data, we show that CACNA1B is required for breast cancer cell migration, invasion and metastasis, but has no effect on proliferation. Importantly, we show that CACNA1B is highly expressed in breast cancer cell lines but not in normal breast epithelial cells or in normal breast tissue or in any normal adult tissues except brain. We also show in five matched pairs of tumor samples, CACNA1B is overexpressed in the metastatic tumor compared to the primary tumor, thus supporting the premise that this ion channel promotes metastasis. Based on these findings, we hypothesize that CACNA1B is a critical regulator of breast cancer development. Because FDA-approved inhibitors are available for this protein, we posit that this channel protein is also an exciting new therapeutic target in breast cancer. In order to determine the molecular mechanisms underlying CACNA1B function in metastasis, and to validate its potential as a therapeutic target, we propose the following aims: 1. To determine CACNA1B and its signaling molecules as prognosis biomarkers in clinical breast cancer samples; 2. To elucidate the signaling pathway of the calcium channel CACNA1B in breast cancer cell migration and invasion; 3. To determine the functions and mechanisms of CACNA1B and its signaling pathway in cell invasion in 3D breast cancer organoid model; 4. To test the hypothesis that CACNA1B can be used in therapeutic targeting of metastasis.

离子通道与多种神经系统疾病有关，但在癌症中的作用却知之甚少。通过乳腺癌基因组学分析，我们发现钙离子通道CACNA1B的表达与乳腺癌患者存活相关，CACNA1B是乳腺癌细胞侵袭和转移所必需的。CACNA1B在乳腺癌细胞系中高表达，在正常乳腺组织不表达，在转移性肿瘤中表达更高。基于上述发现，我们推测CACNA1B是乳腺癌侵袭转移的关键调节因子，确定CACNA1B在乳腺癌侵袭转移中的功能及分子机制，同时验证CACNA1B的抑制剂齐考诺肽的效果，将为乳腺癌转移的治疗提供新靶点。因此，我们提出以下研究目标：1.确定CACNA1B及其信号分子是乳腺癌转移的关键调节点; 2.确定CACNA1B在乳腺癌细胞迁移侵袭转移中的信号传导途径; 3. 通过三维乳腺癌器官模型阐明CACNA1B及其信号通路在细胞侵袭中的作用和机制; 4.验证CACNA1B抑制剂齐考诺肽对乳腺癌转移的治疗作用。

CACNA1B属于电压门控钙离子渗透通道，对膜电位变化敏感。CACNA1B只表达于脑和神经系统。钙信号在细胞增殖、凋亡、细胞迁移和侵袭中起重要作用。然而，钙通道是否是乳腺癌发生或转移的驱动力，乳腺癌中钙信号的改变是否可以作为治疗乳腺癌转移的靶点，这些问题尚无明确答案。.我们前期通过对乳腺癌组织基因表达数据分析，发现离子通道蛋白CACNA1B的高表达与乳腺癌的生存率呈显著负相关。高表达的钙通道CACNA1B是预后不良的标志物。CACNA1B可以影响乳腺癌细胞迁移、侵袭和转移。敲除人乳腺癌细胞CACNA1B能够显著降低小鼠模型中癌细胞的转移。.为阐明CACNA1B的分子机制，我们建立了CACNA1B过表达以及表达敲低的慢病毒质粒。CACNA1B过表达慢病毒感染CACNA1B表达低的细胞系，CACNA1B表达敲低的慢病毒感染CACNA1B表达高的细胞系。我们发现CACNA1B调控Src磷酸化和Cortactin表达。Cortactin是侵袭伪足的重要组成部分。侵袭伪足是癌细胞的前突结构并反映相关的蛋白水解酶活性，为癌细胞提供重塑细胞外基质的能力。侵袭伪足促进了侵入性迁移及其形成与癌细胞侵袭性和转移潜能相关。我们发现CACNA1B是侵袭伪足形成和基质降解的必需和必要条件。因此，CACNA1B通过调控Src磷酸化和Cortactin表达影响侵袭性伪足形成和基质降解，从而促进乳腺癌转移。