Patterns of gene expression in pituitary carcinomas and adenomas analyzed by high-density oligonucleotide arrays, reverse transcriptase-quantitative PCR, and protein expression.

Abstract

Very few of the genes that are important in pituitary tumor initiation, progression, and metastasis have been identified to date. To identify potential genes that may be important in pituitary tumor progression and carcinoma development, we used Affymetrix GeneChip HGU-133A-oligonucleotide arrays, which contain more than 15,000 characterized genes from the human genome to study gene expression in an ACTH pituitary carcinoma metastatic to the liver and four pituitary adenomas. Reverse-transcriptase real-time quantitative- PCR (RT-qPCR) was then used to analyze 4 nonneoplastic pituitaries, 19 adenomas, and the ACTH carcinoma. A larger series of pituitary adenomas and carcinomas were also analyzed for protein expression using tissue microarrays (TMA) (n = 233) and by Western blotting (n = 18). There were 4298 genes that were differentially expressed among the adenomas compared to the carcinoma, with 2057 genes overexpressed and 2241 genes underexpressed in the adenomas. The beta-galactoside binding protein galactin-3 was underexpressed in some adenomas compared to the carcinomas. Prolactin (PRL) and ACTH tumors had the highest levels of expression of galectin-3. The human achaetescute homolog-1 ASCL1 (hASH-1) gene was also underexpressed in some adenomas compared to the carcinoma. Prolactin and ACTH tumors had the highest levels of expression of hASH-1. ID2, which has an important role in cell development and tumorigenesis, was underexpressed in some adenomas compared to the carcinomas. Transducin-like enhancer of split four/ Groucho (TLE-4) was over-expressed in adenomas compared to the ACTH carcinoma. The differential expression of these genes was validated by RT-qPCR, by immunohistochemistry using TMA and by Western blotting. These results indicate that the LGALS3, hASH1, ID2, and TLE-4 genes may have important roles in the development of pituitary carcinomas.

• Authors: Katharina H Ruebel, Alexey A Leontovich, Long Jin, Gail A Stilling, Heyu Zhang, Xiang Qian, Nobuki Nakamura, Bernd W Scheithauer, Kalman Kovacs, Ricardo V Lloyd
• Journal: Endocrine (Endocrine) Vol. 29 Issue 3 Pg. 435-44 (Jun 2006) ISSN: 1355-008X [Print] United States
• PMID: 16943582 (Publication Type: Comparative Study, Journal Article, Research Support, N.I.H., Extramural, Validation Study)

Chemical References

• DNA-Binding Proteins
• GRB2 Adaptor Protein
• GRB2 protein, human
• ID2 protein, human
• Inhibitor of Differentiation Protein 2
• Nuclear Proteins
• Repressor Proteins
• TLE4 protein, human
• Luteinizing Hormone
• Follicle Stimulating Hormone

Topics

• ACTH-Secreting Pituitary Adenoma (metabolism)
• Adenoma (genetics, metabolism)
• Blotting, Western
• Carcinoma (genetics, metabolism)
• DNA-Binding Proteins (metabolism)
• Follicle Stimulating Hormone (metabolism)
• GRB2 Adaptor Protein (metabolism)
• Gene Expression Profiling (methods)
• Growth Hormone-Secreting Pituitary Adenoma (metabolism)
• Humans
• Immunohistochemistry
• Inhibitor of Differentiation Protein 2 (metabolism)
• Luteinizing Hormone (metabolism)
• Nuclear Proteins (metabolism)
• Oligonucleotide Array Sequence Analysis (methods)
• Pituitary Neoplasms (genetics, metabolism)
• Prolactinoma (metabolism)
• Repressor Proteins (metabolism)
• Reverse Transcriptase Polymerase Chain Reaction (methods)