Study of pit-1 gene expression in human pituitary adenomas

研究了垂体腺瘤（13例GH细胞腺瘤、7例PRL细胞腺瘤、3例TSH细胞腺瘤、4例ACTH细胞腺瘤和10例临床无功能腺瘤）中Pit-1及其亚型、GH、PRL和TSH β mrna的表达。Pit-1 mRNA不仅在正常人和大鼠垂体中表达，在所有GH、PRL和TSH细胞腺瘤中也表达。在这三种类型的腺瘤中，Pit-1转录物与生物学行为或组织学结果之间没有相关性，这表明Pit-1通常是决定细胞表型所必需的，但在这些垂体腺瘤中，它不足以调节激素活性和肿瘤生长。此外，Pit-1在部分ACTH细胞（2/4）和无功能腺瘤（7/10）中也有表达。虽然在Pit-1 mRNA阴性的ACTH细胞和无功能腺瘤中没有GH、PRL和TSH β转录物，但在所有Pit-1 mRNA阳性的ACTH细胞腺瘤中均检测到PRL mRNA，在7个Pit-1 mRNA阳性的无功能腺瘤中有4个检测到GH、PRL和/或TSH β mRNA。相比之下，只有三种非功能腺瘤中没有任何GH、PRL或TSH β转录物表达Pit-1 mRAN，这表明在这些非功能腺瘤中真正表达了Pit-1基因。这些数据表明，在这两种类型的腺瘤中，Pit-1 mRAN的表达主要归因于GH、PRL和/或TSH β mRNA表达细胞的存在，而在无功能腺瘤中发现真正的Pit-1转录物可能是罕见的事件。此外，有2例表达了Pit-1 α mRNA，但未显示其他Pit-1异构体mRNA。然而，两种仅表达Pit-1 α mRNA的腺瘤和其他同时表达Pit-1 α mRNA和其他Pit-1异构体mRNA的腺瘤之间没有临床和组织学差异。

Expression of the Pit-1, its isoforms, GH,PRL and TSH beta mRNAs were studied in human pituitary adenomas (13 GH cell adenomas, 7 PRL cell adenomas, 3 TSH cell adenomas, 4 ACTH cell adenomas, and 10 clinically nonfunctioning adenomas).Pit-1 mRNA was not only expressed in normal hman and rat pituitaries, but also in all GH,PRL,and TSH cell adenomas. These was no correlation between Pit-1 transcripts and biological behavior or histological findings in these three types of adenomas, suggesting that Pit-1 is generally required for the determination of cell phenotype, but is insufficient for the regulation of hormonal activity and tumor growth in these pituitary adenomas. In addition, Pit-1 was also expressed in some ACTH cell (2/4) and nonfunctioning adenomas (7/10). Whereas there were no GH,PRL,and TSH beta transcripts in Pit-1 mRNA-negative ACTH cell and nonfunctioning adenomas, PRL mRNA was detected in all Pit-1 mRNA-positive ACTH cell adenomas and GH,PRL,and/or TSH beta mRNA were found in four of seven Pit-1 mRNA-positive nonfunctioning adenomas. In contrast, Pit-1 mRAN was expressed withot any GH,PRL,or TSH beta transcripts in only three nontunctining adenomas, indicating real Pit-1 gene expression in these nonfunctioning adenomas. These data suggest that expression of Pit-1 mRAN in these two types of adenomas can be mainly attributed to the presence of GH,PRL and/or TSH beta mRNA expressing cells and that true Pit-1 transcripts found in nonfunctioning adenomas may be a rare event. Moreover, there were two cases which expressed Pit-1 alpha mRNA,but failed to show other Pit-1 isoform mRNA.There were, however, no clinical and histological differences between these two adenomas showing only Pit-1 alpha mRNA and the others expressing both Pit-1 alpha mRNA and other Pit-1 isoform mRNA.