Citations

Abstract Prostate cancer, a complex disease, can be relatively harmless or extremely aggressive. To identify candidate genes involved in causal pathways of aggressive prostate cancer, we implemented a systems biology approach by combining differential expression analysis and coexpression network analysis to evaluate transcriptional profiles using lymphoblastoid cell lines from 62 prostate cancer patients with aggressive phenotype (Gleason grade ≥ 8) and 63 prostate cancer patients with nonaggressive phenotype (Gleason grade ≤ 5). From 13,935 mRNA genes and 273 microRNAs (miRNA) tested, we identified significant differences in 1,100 mRNAs and 7 miRNAs with a false discovery rate (FDR) of <0.01. We also identified a coexpression module demonstrating significant association with the aggressive phenotype of prostate cancer (P = 3.67 × 10−11). The module of interest was characterized by overrepresentation of cell cycle–related genes (FDR = 3.50 × 10−50). From this module, we further defined 20 hub genes that were highly connected to other genes. Interestingly, 5 of the 7 differentially expressed miRNAs have been implicated in cell cycle regulation and 2 (miR-145 and miR-331-3p) are predicted to target 3 of the 20 hub genes. Ectopic expression of these two miRNAs reduced expression of target hub genes and subsequently resulted in cell growth inhibition and apoptosis. These results suggest that cell cycle is likely to be a molecular pathway causing aggressive phenotype of prostate cancer. Further characterization of cell cycle–related genes (particularly, the hub genes) and miRNAs that regulate these hub genes could facilitate identification of candidate genes responsible for the aggressive phenotype and lead to a better understanding of prostate cancer etiology and progression. [Cancer Res 2009;69(24):9490–7]

Mutations in the electrogenic Na+/ nHCO3− cotransporter (NBCe1, SLC4A4) cause severe proximal renal tubular acidosis, glaucoma, and cataracts in humans, indicating NBCe1 has a critical role in acid-base homeostasis and ocular fluid transport. To better understand the homeostatic roles and protein ontogeny of NBCe1, we have cloned, localized, and downregulated NBCe1 expression in zebrafish, and examined its transport characteristics when expressed in Xenopus oocytes. Zebrafish NBCe1 (zNBCe1) is 80% identical to published mammalian NBCe1 cDNAs. Like other fish NBCe1 clones, zebrafish NBCe1 is most similar to the pancreatic form of mammalian NBC (Slc4a4-B) but appears to be the dominant isoform found in zebrafish. In situ hybridization of embryos demonstrated mRNA expression in kidney pronephros and eye by 24 h postfertilization (hpf) and gill and brain by 120 hpf. Immunohistochemical labeling demonstrated expression in adult zebrafish eye and gill. Morpholino knockdown studies demonstrated roles in eye and brain development and caused edema, indicating altered fluid and electrolyte balance. With the use of microelectrodes to measure membrane potential ( Vm), voltage clamp (VC), intracellular pH (pHi), or intracellular Na+ activity ( aNai), we examined the function of zNBCe1 expressed in Xenopus oocytes. Zebrafish NBCe1 shared transport properties with mammalian NBCe1s, demonstrating electrogenic Na+ and HCO3− transport as well as similar drug sensitivity, including inhibition by 4,4′-diiso-thiocyano-2,2′-disulfonic acid stilbene and tenidap. These data indicate that NBCe1 in zebrafish shares many characteristics with mammalian NBCe1, including tissue distribution, importance in systemic water and electrolyte balance, and electrogenic transport of Na+ and HCO3−. Thus zebrafish promise to be useful model system for studies of NBCe1 physiology.

The objective of this study was to determine the impact of lupus nephritis disease activity on maternal and foetal outcomes in pregnant patients with systemic lupus erythematosus (SLE). Medical records of all pregnant patients with SLE treated at our institution between 1976 and 2007 were reviewed. All patients met American College of Rheumatology classification criteria for SLE. Demographic data, history of lupus nephritis, nephritis disease activity and maternal and foetal outcomes of pregnancy were abstracted. Active lupus nephritis was defined as the presence of proteinuria >0.5 g/day and/or active urinary sediment with or without an elevation in serum creatinine (Cr). Quiescent lupus nephritis was confirmed in the presence of proteinuria <0.5 mg/day and inactive urinary sediment. We identified 58 patients with 90 pregnancies. Compared with pregnancies in SLE patients without renal involvement ( n = 47), pregnancies in patients with active lupus nephritis ( n = 23) were associated with a higher incidence of maternal complications (57% vs 11%, P < 0.001), whereas those with quiescent lupus nephritis ( n = 20) were not (35% vs 11%, P = 0.10). Women with active lupus nephritis were more likely to deliver preterm than women without lupus nephritis, median of 34 weeks vs 40 gestational weeks, respectively ( P = 0.002) and were more likely to suffer foetal loss (35% vs 9%, P = 0.031). Active, but not quiescent, lupus nephritis during pregnancy is associated with a higher incidence of maternal and foetal complications compared with pregnancies in SLE patients without renal involvement.

Abstract The mitochondrion, conventionally thought to be an organelle specific to energy metabolism, is in fact multifunctional and implicated in many diseases, including cancer. To evaluate whether mitochondria-related genes are associated with increased risk for prostate cancer, we genotyped 24 single-nucleotide polymorphisms (SNP) within the mitochondrial genome and 376 tagSNPs localized to 78 nuclear-encoded mitochondrial genes. The tagSNPs were selected to achieve ≥80% coverage based on linkage disequilibrium. We compared allele and haplotype frequencies in ∼1,000 prostate cancer cases with ∼500 population controls. An association with prostate cancer was not detected for any of the SNPs within the mitochondrial genome individually or for 10 mitochondrial common haplotypes when evaluated using a global score statistic. For the nuclear-encoded genes, none of the tagSNPs were significantly associated with prostate cancer after adjusting for multiple testing. Nonetheless, we evaluated unadjusted P values by comparing our results with those from the Cancer Genetic Markers of Susceptibility (CGEMS) phase I data set. Seven tagSNPs had unadjusted P ≤ 0.05 in both our data and in CGEMS (two SNPs were identical and five were in strong linkage disequilibrium with CGEMS SNPs). These seven SNPs (rs17184211, rs4147684, rs4233367, rs2070902, rs3829037, rs7830235, and rs1203213) are located in genes MTRR, NDUFA9, NDUFS2, NDUFB9, and COX7A2, respectively. Five of the seven SNPs were further included in the CGEMS phase II study; however, none of the findings for these were replicated. Overall, these results suggest that polymorphisms in the mitochondrial genome and those in the nuclear-encoded mitochondrial genes evaluated are not substantial risk factors for prostate cancer. (Cancer Epidemiol Biomarkers Prev 2008;17(12):3558–66)

The Dahl salt-sensitive rat is a widely used model of human salt-sensitive forms of hypertension. The kidney plays an important role in the pathogenesis of Dahl salt-sensitive hypertension, but the molecular mechanisms involved remain a subject of intensive investigation. Gene expression profiling studies suggested that 11β-hydroxysteroid dehydrogenase type 1 might be dysregulated in the renal medulla of Dahl salt-sensitive rats. Additional analysis confirmed that renal medullary expression of 11β-hydroxysteroid dehydrogenase type 1 was downregulated by a high-salt diet in SS-13BN rats, a consomic rat strain with reduced blood pressure salt sensitivity, but not in Dahl salt-sensitive rats. 11β-Hydroxysteroid dehydrogenase type 1 is known to convert inactive 11-dehydrocorticosterone to active corticosterone. The urinary corticosterone/11-dehydrocorticosterone ratio as well as urinary excretion of corticosterone was higher in Dahl salt-sensitive rats than in SS-13BN rats. Knockdown of renal medullary 11β-hydroxysteroid dehydrogenase type 1 with small-interfering RNA attenuated the early phase of salt-induced hypertension in Dahl salt-sensitive rats and reduced urinary excretion of corticosterone. Knockdown of 11β-hydroxysteroid dehydrogenase type 1 did not affect blood pressure in SS-13BN rats. Long-term attenuation of salt-induced hypertension was achieved with small hairpin RNA targeting renal medullary 11β-hydroxysteroid dehydrogenase type 1. In summary, we have demonstrated that suppression of 11β-hydroxysteroid dehydrogenase type 1 expression in the renal medulla attenuates salt-induced hypertension in Dahl salt-sensitive rats.

Abstract Pancreatic cancer is a highly lethal malignancy, and the majority of patients succumb to the disease within 2 years. We evaluated the role of variants of mitochondrial DNA and mitochondrial haplogroups in predicting prognosis of patients with pancreatic cancer. A total of 24 mitochondrial single nucleotide polymorphisms were genotyped in 990 patients with pancreatic cancer. After adjusting for covariates and multiple comparisons, no association between any of the mitochondrial single nucleotide polymorphisms or haplogroups and survival was observed. (Cancer Epidemiol Biomarkers Prev 2008;17(9):2512–3)

Abstract Two cytidine analogues, gemcitabine (dFdC) and 1-β-d-arabinofuranosylcytosine (AraC), show significant therapeutic effect in a variety of cancers. However, response to these drugs varies widely. Evidence from tumor biopsy samples shows that expression levels for genes involved in the cytidine transport, metabolism, and bioactivation pathway contribute to this variation in response. In the present study, we set out to test the hypothesis that variation in gene expression both within and outside of this “pathway” might influence sensitivity to gemcitabine and AraC. Specifically, Affymetrix U133 Plus 2.0 GeneChip and cytotoxicity assays were performed to obtain basal mRNA expression and IC50 values for both drugs in 197 ethnically defined Human Variation Panel lymphoblastoid cell lines. Genes with a high degree of association with IC50 values were involved mainly in cell death, cancer, cell cycle, and nucleic acid metabolism pathways. We validated selected significant genes by performing real-time quantitative reverse transcription-PCR and selected two representative candidates, NT5C3 (within the pathway) and FKBP5 (outside of the pathway), for functional validation. Those studies showed that down-regulation of NT5C3 and FKBP5 altered tumor cell sensitivity to both drugs. Our results suggest that cell-based model system studies, when combined with complementary functional characterization, may help to identify biomarkers for response to chemotherapy with these cytidine analogues. [Cancer Res 2008;68(17):7050–8]

Abstract AZD6244 (ARRY 142886) is a potent and selective mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) kinase (MEK) inhibitor currently in early clinical trials. We examined the activity of AZD6244 in a panel of non–small cell lung cancer and a panel of cell lines representing many cancer types using in vitro growth assays. AZD6244 induced G0-G1 cell cycle arrest in sensitive cell lines that primarily included cells containing the BRAF V600E mutation. In these cells, G0-G1 arrest is accompanied by the up-regulation of the cell cycle inhibitors p21WAF1 and p27Kip1 and down-regulation of cyclin D1. In the majority of cell lines tested, including those with K-ras or non-V600E BRAF mutations, AZD6244 induced the accumulation of phospho-MEK, an effect not observed in the most sensitive BRAF V600E-containing cells. Accumulation of phospho-MEK in non–V600E-containing cell lines is due to abrogation of negative feedback pathways. BRAF V600E disrupts negative feedback signaling, which results in enhanced baseline phospho-MEK expression. Exogenous expression of BRAF V600E disrupts feedback inhibition but does not sensitize cells to AZD6244. Specific suppression of endogenous BRAF V600E does not confer resistance to AZD6244 but enhances sensitivity to AZD6244. Thus, our findings show that BRAF V600E marks cells with an in vitro requirement for MAPK signaling to support proliferation. These cells are exquisitely sensitive to AZD6244 (IC50, &lt;100 nmol/L), have high baseline levels of phospho-MEK, and lack feedback inhibition between ERK and Raf. These data suggest an approach to identifying cells that may be sensitive to AZD6244 and other MEK inhibitors. [Cancer Res 2008;68(15):6145–53]