title: GABA receptor expression in benign and malignant thyroid tumors.
abstract: Neurotransmitter systems have recently been shown to be involved in multiple malignancies including breast, colon and prostate cancers. The role of neurotransmitters and neurotrophic factors has not yet been examined in thyroid cancer. To determine the possible involvement of neurotransmitter systems in thyroid carcinogenesis we characterized the patterns of gamma-aminobutyric acid (GABA) receptor expression in normal thyroid and thyroid tumors. We examined the expression patterns of the GABAergic system in 70 human thyroid tumor samples (13 follicular adenomas, 14 follicular carcinomas, 43 papillary carcinomas) and adjacent normal thyroid by immunohistochemistry. GABAergic system mRNA expression in thyroid cancer cell lines derived from primary (FTC133) and metastatic tumors (FTC236 and FTC238) was examined by real time PCR. Overall, GABA receptor expression is increased in tumors compared to normal thyroid tissue. Expression of GABAA receptor beta2 was detected in the vasculature of normal thyroid and thyroid tumors but not in thyroid cancer cells. GABAA alpha2 was detected in metastatic-derived but not in primary-tumor derived cell lines. Expression levels of GABAB R2 and GABA receptor associated protein (GABARAP) are increased in adenomas and thyroid cancer suggesting their role in early stages of thyroid tumorigenesis. This study represents the first demonstration of GABA receptor expression in human thyroid tissue and suggests that the GABAergic system is involved in thyroid carcinogenesis.
authors.affiliation: Department of Pediatrics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD, 20814, USA. sroberts@usuhs.mil
authors.forename: Stephen S
authors.initials: SS
authors.lastname: Roberts
authors.forename: Maria Cecilia
authors.initials: MC
authors.lastname: Mendonça-Torres
authors.forename: Kirk
authors.initials: K
authors.lastname: Jensen
authors.forename: Gary L
authors.initials: GL
authors.lastname: Francis
authors.forename: Vasyl
authors.initials: V
authors.lastname: Vasko
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D018263:Adenocarcinoma, Follicular / Q000378:metabolism / Q000473:pathology; D000236:Adenoma / Q000378:metabolism / Q000473:pathology; D051017:Apoptosis Regulatory Proteins; D002291:Carcinoma, Papillary / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D006801:Humans; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D018079:Receptors, GABA / Q000378:metabolism*; D011963:Receptors, GABA-A / Q000378:metabolism; D018080:Receptors, GABA-B / Q000378:metabolism; D012189:Retrospective Studies; D013961:Thyroid Gland / Q000378:metabolism* / Q000473:pathology; D013964:Thyroid Neoplasms / Q000378:metabolism* / Q000473:pathology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D051017:Apoptosis Regulatory Proteins; C116741:GABARAP protein, human; D008869:Microtubule-Associated Proteins; D018079:Receptors, GABA; D011963:Receptors, GABA-A; D018080:Receptors, GABA-B