Department of Biomorphology and Biotechnologies, University of Messina, Italy.
Cells Tissues Organs. 2012;195(6):550-62. doi: 10.1159/000329508. Epub 2011 Nov 8.
The sarcoglycan complex, consisting of α-, β-, γ-, δ- and ε-sarcoglycans, is a multimember transmembrane system providing a mechanosignaling connection from the cytoskeleton to the extracellular matrix. Whereas the expression of α- and γ-sarcoglycan is restricted to striated muscle, other sarcoglycans are widely expressed. Although many studies have investigated sarcoglycans in all muscle types, insufficient data are available on the distribution of the sarcoglycan complex in nonmuscle tissue. On this basis, we used immunohistochemical and RT-PCR techniques to study preliminarily the sarcoglycans in normal glandular breast tissue (which has never been studied in the literature on these proteins) to verify the effective wider distribution of this complex. Moreover, to understand the role of sarcoglycans, we also tested samples obtained from patients affected by fibrocystic mastopathy and breast fibroadenoma. Our data showed, for the first time, that all sarcoglycans are always detectable in all normal samples both in epithelial and myoepithelial cells; in pathological breast tissue, all sarcoglycans appeared severely reduced. These data demonstrated that all sarcoglycans, not only β-, δ-, and ε-sarcoglycans, have a wider distribution, implying a new unknown role for these proteins. Moreover, in breast diseases, sarcoglycans containing cadherin domain homologs could provoke a loss of strong adhesion between epithelial cells, permitting and facilitating the degeneration of these benign breast tumors into malignant tumors. Consequently, sarcoglycans could play an important and intriguing role in many breast diseases and in particular in tumor progression from benign to malignant.
肌聚糖复合物由α-、β-、γ-、δ-和ε-肌聚糖组成，是一个多成员跨膜系统，提供了从细胞骨架到细胞外基质的机械信号连接。虽然α-和γ-肌聚糖的表达仅限于横纹肌，但其他肌聚糖广泛表达。尽管许多研究已经调查了所有肌肉类型中的肌聚糖，但关于非肌肉组织中肌聚糖复合物的分布，数据仍然不足。在此基础上，我们使用免疫组织化学和 RT-PCR 技术初步研究了正常乳腺组织中的肌聚糖（这些蛋白在文献中从未研究过），以验证该复合物的广泛分布。此外，为了了解肌聚糖的作用，我们还测试了来自患有纤维囊性乳腺炎和乳腺纤维腺瘤的患者的样本。我们的数据首次表明，所有肌聚糖在所有正常样本中（上皮细胞和肌上皮细胞中）都始终可检测到；在病理性乳腺组织中，所有肌聚糖都明显减少。这些数据表明，所有肌聚糖，不仅是β-、δ-和ε-肌聚糖，都有更广泛的分布，暗示这些蛋白具有新的未知作用。此外，在乳腺疾病中，含有钙黏蛋白结构域同源物的肌聚糖可能会引起上皮细胞之间强粘附的丧失，从而允许和促进这些良性乳腺肿瘤向恶性肿瘤的退化。因此，肌聚糖可能在许多乳腺疾病中发挥重要且有趣的作用，特别是在良性到恶性的肿瘤进展中。
