Mammary cancer is highly prevalent in non-castrated female dogs. Cell-to-cell communication is an important mechanism to maintain homeostasis, and connexins are proteins that assemble to form the communicating gap junctions. In many cancers, communication capacity is reduced; several approaches are being tested in order to increase the communication capacity in cancer cells and, therefore, alter their viability. This study analyzed the effects of the alpha-connexin carboxyl-terminal peptide (αCT1) on canine mammary non-neoplastic and neoplastic epithelial cells. Seven canine epithelial mammary cell lines were used. Among these, one was a normal canine epithelial mammary cell line (LOEC-NMG), two canine mammary adenomas (LOEC-MAd1 and LOEC-MAd2), and four canine mammary adenocarcinomas (LOEC-MCA1, LOEC-MCA2, LOEC-MCA3 and CF41). The αCT1 corresponds to a short Cx43 C-terminal sequence linked to an internalization sequence called the antennapedia. After 24 h of incubation, the medium containing different αCT1 peptide concentrations was added to the cells, and only the culture medium was used for control. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test was used to quantify cell viability before treatment and 48, 72, and 96 h after the treatment. Results showed that the normal mammary epithelial cell line (LOEC-NMG) was resistant to treatment with αCT1, which is consistent with a previous study on human mammary cell lines. One of the adenoma cell lines (LOEC-MAd2) was also resistant to treatment with αCT1, although the other (LOEC-MAd1) was susceptible to treatment, mostly at 72 h after treatment. Regarding the four canine adenocarcinoma cell lines, they differ regarding the susceptibility to the treatment with αCT1. Three cell lines, canine mixed adenocarcinoma (LOEC-MCA1), canine complex adenocarcinoma (LOEC-MCA2), and commercial canine mammary adenocarcinoma cell line CF41, were susceptible to treatment with αCT1, while one canine mammary adenocarcinoma cell line (LOEC-MCA3) was resistant to treatment. In most αCT1 treated cell lines, Cx43 was strongly detected in cell membranes by immunofluorescence. We propose that αCT1 restored the cell-to-cell communication capacity of neoplastic cells and induced inhibitory effects on cell viability.
乳腺肿瘤在未绝育母犬中具有高发病率。细胞间通讯是维持稳态的重要机制，连接蛋白是组装形成通讯性间隙连接的蛋白质。在多种癌症中，细胞通讯能力常出现下降；目前已有多种方法被用于测试增强癌细胞通讯能力，从而改变其生存状态的可能性。本研究分析了α-连接蛋白羧基末端肽（αCT1）对犬乳腺非肿瘤性及肿瘤性上皮细胞的作用。实验采用七种犬乳腺上皮细胞系，包括一种正常犬乳腺上皮细胞系（LOEC-NMG）、两种犬乳腺腺瘤细胞系（LOEC-MAd1和LOEC-MAd2）以及四种犬乳腺腺癌细胞系（LOEC-MCA1、LOEC-MCA2、LOEC-MCA3和CF41）。αCT1由连接蛋白43羧基末端短肽序列与一种称为触角足蛋白的内化序列连接而成。细胞孵育24小时后，分别加入含不同浓度αCT1肽的培养液，对照组仅使用基础培养基。通过3-(4,5-二甲基噻唑-2-基)-2,5-二苯基四氮唑溴盐（MTT）实验检测处理前及处理后48、72、96小时的细胞活力。结果显示：正常乳腺上皮细胞系（LOEC-NMG）对αCT1处理具有耐受性，这与前人关于人类乳腺细胞系的研究结果一致。腺瘤细胞系LOEC-MAd2同样表现耐受性，而LOEC-MAd1则对处理敏感（尤以处理后72小时最为显著）。四种犬腺癌细胞系对αCT1处理的敏感性存在差异：犬混合型腺癌（LOEC-MCA1）、犬复合型腺癌（LOEC-MCA2）及商品化犬乳腺腺癌细胞系CF41对αCT1处理敏感，而犬乳腺腺癌细胞系LOEC-MCA3则表现耐受。免疫荧光检测显示，在多数经αCT1处理的细胞系中，细胞膜上连接蛋白43呈现强阳性表达。本研究认为αCT1能够恢复肿瘤细胞的细胞间通讯能力，并对细胞活力产生抑制作用。
肿瘤(癌症)患者之家