Kazan Jalal M, El-Saghir Jamal, Saliba Jessica, Shaito Abdullah, Jalaleddine Nour, El-Hajjar Layal, Al-Ghadban Sara, Yehia Lamis, Zibara Kazem, El-Sabban Marwan
Department of Anatomy, Cell Biology and Physiological Sciences, Faculty of Medicine, American University of Beirut, Beirut 1107 2020, Lebanon.
Department of Biology, Faculty of Sciences, Lebanese University, Hadath 1003, Lebanon.
Cancers (Basel). 2019 Apr 1;11(4):460. doi: 10.3390/cancers11040460.
Connexins regulate multiple cellular functions and are considered tumor suppressors. Connexin43 (Cx43) is frequently down-regulated in breast tumors. However, Cx43 regulation during cancer onset and metastasis is complex and context-dependent. We investigated the effect of Cx43 over-expression or knock-down on the metastatic potential of MDA-MB-231 breast cancer cells in vitro and in vivo and in human breast cancer tissues. MDA-MB-231 cells over-expressing (Cx43D) or down-regulating Cx43 (shCx43) were generated and used in proliferation, migration, and invasion assays. The regulation of genes/proteins implicated in progression, invasion and metastasis was assessed in vitro and in immune-compromized mice injected with MDA-MB-231, Cx43D or shCx43 cells. Primary tumor onset/growth, metastasis and overall survival of these animals was monitored and evaluated. In addition, Cx43 expression in human breast carcinoma samples was assessed by qPCR. Cx43 over-expression increased protein levels of epithelial markers E-cadherin and zonula occludens 1 expression and resulted in the sequestration of β-catenin at the cell membrane, while Cx43 knock-down induced protein expression of the mesenchymal marker N-cadherin and an increased invasive potential of shCx43 cells. In vivo, in mice xenografted with breast cancer cells, Cx43 over-expression decreased tumor volume, attenuated cell metastasis to lungs and liver and increased overall mice survival. Importantly, the expression of Cx43 in triple negative human breast cancer tissues is also down-regulated. Collectively, Cx43 over-expression induced an epithelial-like phenotype in MDA-MB-231 cells and suppressed tumor growth and metastasis to secondary organs in vivo. In contrast, Cx43 knock-down in MDA-MB-231 cells induced a mesenchymal phenotype with increased cell invasion leading to an enhanced metastatic phenotype. These data provide evidence for a pivotal role of Cx43 in breast cancer metastasis and support the potential targeting of connexins in breast cancer therapy.
连接蛋白调节多种细胞功能，被认为是肿瘤抑制因子。连接蛋白43（Cx43）在乳腺肿瘤中经常下调。然而，Cx43在癌症发生和转移过程中的调节是复杂的且依赖于背景。我们研究了Cx43过表达或敲低对MDA-MB-231乳腺癌细胞在体外、体内以及人乳腺癌组织中的转移潜能的影响。构建了过表达（Cx43D）或下调Cx43（shCx43）的MDA-MB-231细胞，并用于增殖、迁移和侵袭实验。在体外以及注射了MDA-MB-231、Cx43D或shCx43细胞的免疫缺陷小鼠中，评估了与进展、侵袭和转移相关的基因/蛋白的调节情况。监测并评估了这些动物的原发性肿瘤发生/生长、转移和总体生存期。此外，通过qPCR评估了人乳腺癌样本中Cx43的表达。Cx43过表达增加了上皮标志物E-钙黏蛋白和紧密连接蛋白1的蛋白水平，并导致β-连环蛋白在细胞膜上的隔离，而Cx43敲低诱导了间充质标志物N-钙黏蛋白的蛋白表达，并增加了shCx43细胞的侵袭潜能。在体内，在接种了乳腺癌细胞的小鼠中，Cx43过表达减小了肿瘤体积，减弱了细胞向肺和肝的转移，并提高了小鼠的总体生存期。重要的是，三阴性人乳腺癌组织中Cx43的表达也下调。总的来说，Cx43过表达在MDA-MB-231细胞中诱导了上皮样表型，并在体内抑制了肿瘤生长和向次级器官的转移。相反，MDA-MB-231细胞中Cx43敲低诱导了间充质表型，增加了细胞侵袭，导致转移表型增强。这些数据为Cx43在乳腺癌转移中的关键作用提供了证据，并支持在乳腺癌治疗中对连接蛋白进行潜在靶向治疗。
