Differential pituitary gene expression profiles associated- to aging and spontaneous tumors as revealed by rat cDNA expression array

Chronic hypoxia changes gene expression profile of primary rat carotid body cells: consequences on the expression of NOS isoforms and ET-1 receptors

Sustained chronic hypoxia (CH) produces morphological and functional changes in the carotid body (CB). Nitric oxide (NO) and endothelin-1 (ET-1) play a major role as modulators of the CB oxygen chemosensory process. To characterize the effects of CH related to normoxia (Nx) on gene expression, particularly on ET-1 and NO pathways, primary cultures of rat CB cells were exposed to 7 days of CH. Total RNA was extracted, and cDNA-32P was synthesized and hybridized with 1,185 genes printed on a nylon membrane Atlas cDNA Expression Array. Out of 324 differentially expressed genes, 184 genes were upregulated, while 140 genes were downregulated. The cluster annotation and protein network analyses showed that both NO and ET-1 signaling pathways were significantly enriched and key elements of each pathway were differentially expressed. Thus, we assessed the effect of CH at the protein level of nitric oxide synthase (NOS) isoforms and ET-1 receptors. CH induced an increase in the expression of endothelial NOS, inducible NOS, and ETB. During CH, the administration of SNAP, a NO donor, upregulated ETB. Treatment with Tezosentan (ET-1 receptor blocker) during CH upregulated all three NOS isoforms, while the NOS blocker L-NAME induced upregulation of iNOS and ETB and downregulated the protein levels of ETA. These results show that CH for 7 days changed the cultured cell CB gene expression profile, the NO and ET-1 signaling pathways were highly enriched, and these two signaling pathways interfered with the protein expression of each other.

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

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.

Motor hyperactivity caused by a deficit in dopaminergic neurons and the effects of endocrine disruptors: a study inspired by the physiological roles of PACAP in the brain

Recent studies have revealed that the pituitary adenylate cyclase-activating polypeptide (PACAP) might act as a psychostimulant. Here we investigated the mechanisms underlying motor hyperactivity in patients with pervasive developmental disorders, such as autism, and attention-deficit hyperactivity disorder (ADHD). We studied the effects of intracisternal administration of 6-hydroxydopamine (6-OHDA) or endocrine disruptors (EDs) on spontaneous motor activity (SMA) and multiple gene expression in neonatal rats. Treatment with 6-OHDA caused significant hyperactivity during the dark phase in rats aged 4-5 weeks. Motor hyperactivities also were observed after treatment with endocrine disruptors, such as bisphenol A, nonylphenol, diethylhexyl phthalate and dibutyl phthalate, during both dark and light phases. Gene-expression profiles produced using cDNA macroarrays of 8-week-old rats with 6-OHDA lesions revealed the altered expression of several classes of gene, including the N-methyl-D-aspartate (NMDA) receptor 1, glutamate/aspartate transporter, gamma-aminobutyric-acid transporter, dopamine transporter 1, D4 receptor, and peptidergic elements such as the galanin receptor, arginine vasopressin receptor, neuropeptide Y and tachykinin 2. The changes in gene expression caused by treatment with endocrine disruptors differed from those induced by 6-OHDA. These results suggest that the mechanisms underlying the induction of motor hyperactivity and/or compensatory changes in young adult rats might differ between 6-OHDA and endocrine disruptors.

Age-associated changes in hypothalamic and pituitary neuroendocrine gene expression in the rat

A cDNA membrane array displaying 1183 probes was used to detect hypothalamic and pituitary changes in gene expression accompanying ageing and age-associated pituitary macroadenomas. Four groups of male Sprague-Dawley rats (3-, 15-, 24-month-old and 24-month-old with prolactinoma) were compared in two independent hybridizations. cDNA array data were confirmed and completed by comparative reverse transcriptase-polymerase chain reaction on selected genes. The expression of 454 and 116 mRNAs was detected in hypothalamus and pituitary, respectively. Growth hormone (GH) mRNA alone represented 85% of total gene expression in the gland of young rats, and other pituitary hormone transcripts 2.8%, while melanin-concentrating hormone (MCH) mRNA, the most expressed neuropeptide transcript involved in neuroendocrine regulation, accounted for only 0.8% of total hypothalamic transcripts. The proportion of genes modified in the hypothalamus and pituitary was rather modest: 1.5% and 5.2%, respectively, for ageing per se, and 1.1% and 5.2% for age-associated macroprolactinomas. Among pituitary specific RNAs, GH mRNA expression was notably decreased with age. At the hypothalamic level, expression of genes directly involved in GH regulation, such as somatostatin and growth hormone-releasing hormone, was not altered, while neuropeptide transcripts involved in feeding behaviour [orexin/hypocretin, MCH, pro-opiomelanocortin (POMC), cocaine- and amphetamine-regulated transcript (CART)] were significantly altered. In addition, a few ubiquitous transcripts (hnRNP-K, PFKm, CCND 2, calponin and set) were differently affected in both tissues. Modifications in hypothalamic orexigenic (orexin, MCH) and anorexigenic (POMC, CART) gene expression are in keeping with an age-associated decrease in energy consumption but a higher one in the presence of macroprolactinomas.

cDNA array analysis of gene expression following hemorrhagic shock and resuscitation in rats

The aim of this study was to characterize gene expression following hemorrhagic shock and resuscitation with emphasis on the differences between various resuscitation strategies.

METHODS

Male Sprague Dawley rats (n = 25; 5/group) were subjected to a three stage hemorrhage and resuscitated as follows: (1) sham hemorrhage; (2) sham resuscitation; (3) lactated Ringer's solution (LR), 3:1 volume; (4) 7.5% hypertonic saline (HTS) 9.7 ml/kg; (5) plasma, 1:1 volume. Liver, spleen, lung and muscle were collected 3 h post resuscitation and cDNA array analysis was performed on the total RNA.

RESULTS

Expression of 1,176 genes was analyzed. Following resuscitation, 82 of the genes studied (7%) displayed an altered expression of at least 2-fold compared to the sham hemorrhage group. Depending on organ system under study and resuscitation conditions, expression of these 82 genes was down- or up-regulated, bringing the total number of expression alterations to 167. Largest number of organ-specific changes in gene expression was noted in liver (63/167), followed by lung (57), muscle (25), and spleen (22). Most of the resuscitation strategy specific changes were caused by plasma resuscitation (68/167), followed by LR (51), and HTS (48). In every organ studied, gene expression profile was dependent upon the fluid used for resuscitation.

CONCLUSION

Cellular response to hemorrhagic shock, even at the level of gene expression, is dependent on the resuscitation strategy. We have discovered altered expression of genes not previously implicated in the physiology of hemorrhagic shock and resuscitation. Gene array technology provides a rapid and efficient means of dissecting the complex genetic regulation of cellular response to shock.

Comparison of gene expression in old versus young rat hippocampus by cDNA array

We sought to identify genes affected by the aging process in the rat hippocampus using cDNA expression array analysis. RNA samples were extracted from the hippocampus of 2-month-old and 20-month-old rats and reverse-transcribed in the presence of [32P]dCTP. Membrane sets of Rat Atlas array 2 (Clontech) were hybridized with cDNA probe sets. Among a total of 1176 cDNAs, 23 showed significant (more than 2-fold) changes between groups. Eight genes were increased in the old group, while the remaining fifteen genes were decreased. Reverse transcription-polymerase chain reaction (RT-PCR) was used to validate the relative expression pattern obtained by the cDNA array. The results were consistent for 20 of the 23 genes tested. Most interesting findings were the decrease in expression of proteins for energy metabolism, proteins involved in secretion, and ribosomal proteins. The possible physiological significance of these changes are discussed.

Ribosomal 18S RNA prevails over glyceraldehyde-3-phosphate dehydrogenase and beta-actin genes as internal standard for quantitative comparison of mRNA levels in invasive and noninvasive human melanoma cell subpopulations

The comparison of the gene expression profiles between two subpopulations of melanoma cells (1C8 and T1C3) derived from the tumor of one patient by cDNA array revealed differences in GAPDH and beta-actin gene levels. These two housekeeping genes were up-regulated in invasive T1C3 melanoma cells compared to noninvasive 1C8 cells. Since cDNA array results were not confirmed by conventional RT-PCR throughout the exponential phase of amplification, we performed duplex relative RT-PCR using ribosomal 18S RNA as internal standard including competimer technology. Statistical analyses provided significant evidence that invasive T1C3 melanoma cells exhibited a twofold higher mRNA level of both GAPDH and beta-actin than noninvasive 1C8 cells. This study demonstrates that the duplex relative RT-PCR procedure including ribosomal 18S RNA as internal standard and competimer technology is precise for RNA quantification and is tailored for cDNA array validation. Our data provide molecular evidence that cellular subpopulations of the same pathological origin are highly heterogeneous and extend the concept that the selection of an appropriate internal control for comparative mRNA analysis should be adapted to each model of human cancers.