Gil-Puig C, Seoane S, Blanco M, Macia M, Garcia-Caballero T, Segura C, Perez-Fernandez R
Department of Physiology, University of Santiago de Compostela, Spain.
Eur J Endocrinol. 2005 Aug;153(2):335-44. doi: 10.1530/eje.1.01962.
The transcription factor pituitary-1 (Pit-1) is mainly expressed in the pituitary gland, where it has critical roles in cell differentiation and as a transcriptional factor for GH and prolactin (PRL). It is also expressed in human extrapituitary tissues (placenta, lymphoid and haematopoietic tissues) and cell lines (human breast adenocarcinoma cells, MCF-7). Despite the widely suggested roles of GH and PRL in the progression of proliferative mammary disorders, Pit-1 expression in human mammary gland has not yet been reported.
To evaluate the expression of Pit-1 in human breast and, using the MCF-7 cell line, to investigate whether Pit-1 overexpression regulates GH expression and increases cell proliferation.
Using real-time RT-PCR, western blotting and immunohistochemistry, we evaluated the expression of Pit-1 mRNA and protein in seven normal human breasts and 14 invasive ductal mammary carcinomas. GH regulation by Pit-1 in MCF-7 cells was evaluated using RT-PCR, western blotting, ELISA and transfection assays. Cell proliferation was evaluated using bromodeoxyuridine.
We found expression of Pit-1 mRNA and protein in both normal and tumorous human breast. We also found that Pit-1 mRNA levels were significantly increased in breast carcinoma compared with normal breast. In MCF-7 cells, Pit-1 overexpression increased GH mRNA and protein concentrations and significantly increased cell proliferation.
These findings indicate that Pit-1 is expressed in human breast, that it regulates endogenous human mammary GH secretion, and that it increases cell proliferation. This suggests that, depending on its level of expression, Pit-1 may be involved in normal mammary development, breast disorders, or both.
转录因子垂体-1（Pit-1）主要在垂体中表达，在细胞分化过程中以及作为生长激素（GH）和催乳素（PRL）的转录因子发挥关键作用。它也在人类垂体外组织（胎盘、淋巴和造血组织）以及细胞系（人乳腺腺癌细胞，MCF-7）中表达。尽管广泛认为GH和PRL在增殖性乳腺疾病进展中发挥作用，但尚未有关于Pit-1在人乳腺中表达的报道。
评估Pit-1在人乳腺中的表达，并利用MCF-7细胞系研究Pit-1过表达是否调节GH表达并增加细胞增殖。
使用实时逆转录聚合酶链反应（RT-PCR）、蛋白质印迹法和免疫组织化学，我们评估了7例正常人类乳腺组织和14例浸润性导管癌组织中Pit-1 mRNA和蛋白质的表达。利用RT-PCR、蛋白质印迹法、酶联免疫吸附测定（ELISA）和转染试验评估MCF-7细胞中Pit-1对GH的调节作用。使用溴脱氧尿苷评估细胞增殖。
我们发现Pit-1 mRNA和蛋白质在正常和肿瘤性人乳腺组织中均有表达。我们还发现，与正常乳腺相比，乳腺癌组织中Pit-1 mRNA水平显著升高。在MCF-7细胞中，Pit-1过表达增加了GH mRNA和蛋白质浓度，并显著增加了细胞增殖。
这些发现表明Pit-1在人乳腺中表达，它调节内源性人乳腺GH分泌，并增加细胞增殖。这表明，根据其表达水平，Pit-1可能参与正常乳腺发育、乳腺疾病或两者皆有。
