Associations of plasma miRNAs with waist circumference and insulin resistance among women with polycystic ovary syndrome - Pilot study.

BACKGROUND: Insulin resistance (IR) and central obesity are common in polycystic ovary syndrome (PCOS), but pathomechanisms for IR in PCOS are not established. Circulating microRNAs (miRNAs) are non-invasive biomarkers of epigenetic regulation that may contribute to the pathogenesis of IR and central adiposity in PCOS. METHODS: We conducted a pilot study to examine associations of circulating miRNAs with IR and central adiposity among women with PCOS (n = 11) using high-throughput miRNA sequencing. We fit generalized linear models examining associations of waist circumference and HOMA-IR with plasma miRNAs. We used false discovery rate (FDR)-adjusted cutoff p < 0.1 to correct for multiple testing. We used miRDB's Gene Ontology (GO) tool to identify predicted pathways for top hits. RESULTS: Mean age and BMI of participants were 27.9 years and 32.5 kg/m2, respectively. Lower levels of miR-1294 were associated with higher waist circumference (ß = -0.10, FDR = 0.095). While no miRNAs were associated with HOMA-IR at our FDR cut off <0.1, 11 miRNAs were associated with waist circumference and 14 miRNAs with HOMA-IR at unadjusted p < 0.01, including members of the highly conserved miR-17/92 cluster and miR-1294 (ß = -0.10, p < 0.001). The GO analysis of miR-1294 identified 54 overrepresented pathways, including "negative regulation of insulin receptor signaling" (FDR = 0.019), and 6 underrepresented pathways. CONCLUSIONS: Plasma miR-1294 along with members of the miR-17/92 cluster and miRNAs involved in insulin signaling may be associated with central obesity and insulin resistance in PCOS. Larger studies among women with and without PCOS are needed to validate these findings.

Persistence of improved glucose homeostasis in Gclm null mice with age and cadmium treatment.

Antioxidant signaling/communication is among the most important cellular defense and survival pathways, and the importance of redox signaling and homeostasis in aging has been well-documented. Intracellular levels of glutathione (GSH), a very important endogenous antioxidant, both govern and are governed by the Nrf2 pathway through expression of genes involved in its biosynthesis, including the subunits of the rate-limiting enzyme (glutamate cysteine ligase, GCL) in GSH production, GCLC and GCLM. Mice homozygous null for the Gclm gene are severely deficient in GSH compared to wild-type controls, expressing approximately 10% of normal GSH levels. To compensate for GSH deficiency, Gclm null mice have upregulated redox-regulated genes, and, surprisingly, are less susceptible to certain types of oxidative damage. Furthermore, young Gclm null mice display an interesting lean phenotype, resistance to high fat diet-induced diabetes and obesity, improved insulin and glucose tolerance, and decreased expression of genes involved in lipogenesis. However, the persistence of this phenotype has not been investigated into old age, which is important in light of studies which suggest aging attenuates antioxidant signaling, particularly in response to exogenous stimuli. In this work, we addressed whether aging compromises the favorable phenotype of increased antioxidant activity and improved glucose homeostasis observed in younger Gclm null mice. We present data showing that under basal conditions and in response to cadmium exposure (2 mg/kg, dosed once via intraperitoneal injection), the phenotype previously described in young (<6 months) Gclm null mice persists into old age (24+ months). We also provide evidence that transcriptional activation of the Nrf2, AMPK, and PPARγ pathways underlie the favorable metabolic phenotype observed previously in young Gclm null mice.

Association of diabetes susceptibility gene calpain-10 with pancreatic cancer among smokers.

OBJECTIVE: The objective of this study was to test the association between calpain-10 (CAPN10), a diabetes susceptibility gene, with risk of pancreatic cancer (PC). METHODS: DNA samples from 83 incident exocrine PC cases and 166 controls, all of whom were smokers, were genotyped for four markers of CAPN10 in a nested case-control study based on the Beta-Carotene and Retinol Efficacy Trial (CARET), a randomized chemoprevention trial of subjects at high risk of lung cancer. Controls were matched on sex, race, age, CARET intervention arm, duration of exposure to asbestos, and smoking history. Conditional logistic regression was used for statistical analyses. RESULTS: The minor allele of SNP-43 (rs3792267) in intron 3 was associated with increased risk of PC with an odds ratio of 1.57 (95%CI 1.03-2.38, p = 0.035) per allele. The three markers of the highest risk haplotype had an odds ratio of 1.98 (95%CI 1.12-3.49, p = 0.019) for risk of PC compared to the most common haplotype. There was no evidence of interaction between either of these associations by diabetes status. CONCLUSION: These results suggest that variation in CAPN10 may be associated with increased risk of PC among smokers. Thus, studies of genes associated with diabetes risk in PC are warranted in a larger population.

Association between the peroxisome proliferator-activated receptor gamma Pro12Ala variant and haplotype and pancreatic cancer in a high-risk cohort of smokers: a pilot study.

OBJECTIVES: The Pro12Ala variant in the peroxisome proliferator-activated receptor gamma (PPARG) gene has been associated with diabetes and several cancers. This pilot study tested for the association between Pro12Ala and pancreatic cancer risk in a high-risk sample of smokers. METHODS: A nested case-control study was conducted in 83 incident cases of pancreatic cancer and 166 matched controls originally recruited into a cohort chemoprevention study of lung cancer. Associations between Pro12Ala and pancreatic cancer risk were measured using conditional logistic regression. RESULTS: Carriers of the G allele (Ala) of the Pro12Ala variant had a borderline increased relative risk of pancreatic cancer compared with homozygous carriers of the C allele (Pro), with an odds ratio of 1.79 (95% confidence interval [CI], 0.96-3.33; P=0.06). Among subjects randomized to high-dose vitamin A, the odds ratio was 2.80 (95% CI, 1.16-6.74; P=0.02) versus 1.20 (95% CI, 0.45-3.23; P=0.71) in the placebo group. A haplotype including Pro12Ala was also significantly associated with pancreatic cancer risk in all subjects and in subjects randomized to vitamin A. CONCLUSIONS: This analysis presents the first evidence that PPARG may be associated with pancreatic cancer risk, and this candidate gene should be investigated in future, larger studies.

Acetaminophen-induced liver injury is attenuated in male glutamate-cysteine ligase transgenic mice.

Acetaminophen overdose is a leading cause of drug-related acute liver failure in the United States. Glutathione, a tripeptide antioxidant protects cells against oxidative damage from reactive oxygen species and plays a crucial role in the detoxification of xenobiotics, including acetaminophen. Glutathione is synthesized in a two-step enzymatic reaction. Glutamate-cysteine ligase carries out the rate-limiting and first step in glutathione synthesis. We have generated C57Bl/6 mice that conditionally overexpress glutamate-cysteine ligase, and report here their resistance to acetaminophen-induced liver injury. Indices of liver injury included histopathology and serum alanine aminotransferase activity. Male transgenic mice induced to overexpress glutamate-cysteine ligase exhibited resistance to acetaminophen-induced liver injury when compared with acetaminophen-treated male mice carrying, but not expressing glutamate-cysteine ligase transgenes, or to female glutamate-cysteine ligase transgenic mice. We conclude that glutamate-cysteine ligase activity is an important factor in determining acetaminophen-induced liver injury in C57Bl/6 male mice. Because people are known to vary in their glutamate-cysteine ligase activity, this enzyme may also be an important determinant of sensitivity to acetaminophen-induced liver injury in humans.

Genetic Susceptibility to Prostate Cancer: Prostate-specific Antigen and its Interaction with the Androgen Receptor (United States).

OBJECTIVE: To determine whether directly observed prostate-specific antigen (PSA) promoter diploid haplotype, either alone or in conjunction with androgen receptor (AR) genotype, is associated with prostate cancer risk. METHODS: We conducted a case-control study nested within the US population-based Cardiovascular Health Study cohort. Incident prostate cancers were identified by linkage to cancer registry records for the years 1989-2000. We genotyped 193 cases and 391 controls for the PSA -252 G/A and -158 G/A SNPs and the AR CAG microsatellite, and developed methods to directly determine proximal PSA promoter haplotypes. Exact logistic regression was used to estimate odds ratios and significance levels. RESULTS: No significant associations were observed between PSA diplotype and prostate cancer overall. Short (< 20) AR CAG repeat lengths were associated with modest increases in the risk of prostate cancer (OR, 1.46; 95% CI, 0.97-2.19; p = 0.071) that were significant for advanced disease (OR, 1.82; 95% CI, 1.02-3.26; p = 0.044). Men who possessed two copies of the PSA*2 (-252G/-158G) haplotype and short AR CAG repeat lengths had a 4-fold (95% CI, 1.05-20.75; exact p = 0.040) increased risk of prostate cancer, and a 7-fold (95% CI, 1.25-39.78; exact p = 0.026) increased risk of advanced disease. CONCLUSIONS: We found evidence that the PSA*2*2 diplotype in combination with short AR CAG alleles increases a man's risk of developing prostate cancer. These findings support an etiologic role in prostate cancer of genetic interactions between polymorphisms that increase AR transactivation strength and those that alter the regulatory regions of target genes such as PSA that are responsive to androgen stimulation.

Gene expression profiling of nephrotoxicity from the sevoflurane degradation product fluoromethyl-2,2-difluoro-1-(trifluoromethyl)vinyl ether ("compound A") in rats.

The major degradation product of the volatile anesthetic sevoflurane, the haloalkene fluoromethyl-2,2-difluoro-1-(trifluoromethyl)vinyl ether (FDVE or "compound A"), is nephrotoxic in rats. FDVE undergoes complex metabolism and bioactivation, which mediates the nephrotoxicity. Nevertheless, the molecular and cellular mechanisms of FDVE toxification are unknown. This investigation evaluated the gene expression profile of kidneys in rats administered a nephrotoxic dose of FDVE. Male Fischer 344 rats (five per group) received 0.25 mmol/kg intraperitoneal FDVE or corn oil (controls) and were sacrificed after 24 or 72 h. Urine output and kidney histological changes were quantified. Kidney RNA was extracted for microarray analysis using Affymetrix GeneChip Rat Expression Array 230A arrays. Quantitative real-time PCR confirmed the modulation of several genes. FDVE caused significant diuresis and necrosis at 24 h, with normal urine output and evidence of tubular regeneration at 72 h. There were 517 informative genes that were differentially expressed >1.5-fold (p < 0.05) versus control at 24 h, of which 283 and 234 were upregulated and downregulated, respectively. Major classes of upregulated genes included those involved in apoptosis, oxidative stress, and inflammatory response (mostly at 24 h), and regeneration and repair; downregulated genes were generally associated with transporters and intermediary metabolism. Among the quantitatively most upregulated genes were kidney injury molecule, osteopontin, clusterin, tissue inhibitor of metalloproteinase 1, and TNF receptor 12, which have been associated with other forms of nephrotoxicity, and angiopoietin-like protein 4, glycoprotein nmb, ubiquitin hydrolase, and HSP70. Microarray results were confirmed by quantitative real-time PCR. FDVE causes rapid and brisk changes in gene expression, providing potential insights into the mechanism of FDVE toxification, and potential biomarkers for FDVE nephrotoxicity which are more sensitive than conventional measures of renal function.

The Prevalence of CYP2C8, 2C9, 2J2, and soluble epoxide hydrolase polymorphisms in African Americans with hypertension.

BACKGROUND: The cytochrome P450 (CYP) epoxygenase pathway produces arachidonic acid metabolites that are vasoactive, that affect renal sodium handling, and that have been proposed to play a mechanistic role in hypertension. Multiple single nucleotide polymorphisms (SNP) in CYP2C8, 2C9, 2J2 and soluble epoxide hydrolase (sEH) have been identified, many of which have altered functional activity in vitro. We performed a case-control study to determine the prevalence of epoxygenase-related SNP in African American individuals and to evaluate whether these SNP are associated with increased risk of hypertension. METHODS: Normotensive African American individuals (N = 107) and African American patients with hypertension (N = 108) were recruited. DNA was extracted from a venous blood sample and genotyped for CYP2C8*2,*3, CYP2C9*2-*5,*8,*11, CYP2J2 *2-*7, L50L, R49S, V113M, N124S, sEH R287Q, and sEH 403Rins variant alleles by allelic discrimination using real-time polymerase chain reaction. Genotype and allele frequencies were calculated and associations with hypertension were estimated using unconditional logistic regression, adjusting for age and sex. RESULTS: No association was found between any of the variant alleles and hypertension. We did find that only the CYP2C8*3and CYP2C9*2 alleles were in strong linkage disequilibrium in both the hypertensive and healthy African American groups, a finding that was reported previously in healthy individuals of white ethnicity. CONCLUSIONS: These results suggest that these epoxygenase-related SNP are not associated with increased risk of hypertension in the African American population. There was significant linkage disequilibrium between CYP2C8*3 and CYP2C9*2 alleles that was not associated with hypertension.