Clinic for Reproductive Medicine, Unit of Small Animal Reproduction, University of Zurich, Zurich, Switzerland.
BMC Vet Res. 2012 May 30;8:72. doi: 10.1186/1746-6148-8-72.
Mammary tumors represent the most common neoplastic disease in female dogs. Recently, the promoting role of prolactin (PRL) in the development of human breast carcinoma has been shown. Possible proliferative, anti-apoptotic, migratory and angiogenic effects of PRL on human mammary cancer cells in vitro and in vivo were suggested. The effects of PRL are mediated by its receptor, and alterations in receptor expression are likely to play a role in tumor development. Currently, not much data is available about prolactin receptor (PRLR) expression in canine mammary tumors. To set the basis for investigations on the role of PRL in mammary tumorigenesis in this species, prolactin receptor expression was evaluated by semi-quantitative real time PCR and immunohistochemistry on 10 formalin-fixed, paraffin-embedded samples each of canine non-neoplastic mammary tissue, mammary adenomas and adenocarcinomas.
The highest PRLR expression levels were found in normal mammary tissue, while adenomas, and to an even higher degree adenocarcinomas, showed a significant decrease in prolactin receptor expression. Compared to normal tissue, PRLR mRNA was reduced 2.4 fold (p = 0.0261) in adenomas and 4.8 fold (p = 0.008) in adenocarcinomas. PRLR mRNA expression was significantly lower in malignant than in benign lesions (p = 0.0165). Immunohistochemistry demonstrated PRLR expression in all three tissue types with signals mostly limited to epithelial cells.
Malignant transformation of mammary tissue was associated with a decline in prolactin receptor expression. Further studies are warranted to address the functional significance of this finding.
乳腺肿瘤是犬类女性中最常见的肿瘤疾病。最近，催乳素（PRL）在人类乳腺癌发展中的促进作用已被证明。体外和体内研究表明，PRL 对人乳腺癌细胞具有增殖、抗凋亡、迁移和血管生成作用。PRL 的作用是通过其受体介导的，受体表达的改变可能在肿瘤发展中起作用。目前，关于犬乳腺肿瘤中催乳素受体（PRLR）表达的数据还不多。为了为研究 PRL 在该物种乳腺肿瘤发生中的作用奠定基础，通过半定量实时 PCR 和免疫组织化学方法，对 10 例福尔马林固定、石蜡包埋的犬非肿瘤性乳腺组织、乳腺腺瘤和腺癌样本进行了催乳素受体表达评估。
正常乳腺组织中 PRLR 表达水平最高，而腺瘤，甚至更高程度的腺癌，催乳素受体表达显著降低。与正常组织相比，腺瘤中 PRLR mRNA 减少了 2.4 倍（p=0.0261），腺癌中减少了 4.8 倍（p=0.008）。与良性病变相比，恶性病变中 PRLR mRNA 表达显著降低（p=0.0165）。免疫组织化学显示 PRLR 在三种组织类型中均有表达，信号主要局限于上皮细胞。
乳腺组织的恶性转化与催乳素受体表达的下降有关。需要进一步研究来阐明这一发现的功能意义。
