Biomedical subjects

Long-Cheng Li

Publications and source records attributed to Long-Cheng Li.

At least 19 recordsLinked to original sources

PubMed2006

Small dsRNAs induce transcriptional activation in human cells.

Recent studies have shown that small noncoding RNAs, such as microRNAs and siRNAs, regulate gene expression at multiple levels including chromatin architecture, transcription, RNA editing, RNA stability, and translation. Each form of RNA-dependent regulation has been generally found to silence homologous sequences and collectively called RNAi. To further study the regulatory role of small RNAs at the transcriptional level, we designed and synthesized 21-nt dsRNAs targeting selected promoter regions of human genes E-cadherin, p21(WAF1/CIP1) (p21), and VEGF. Surprisingly, transfection of these dsRNAs into human cell lines caused long-lasting and sequence-specific induction of targeted genes. dsRNA mutation studies reveal that the 5' end of the antisense strand, or "seed" sequence, is critical for activity. Mechanistically, the dsRNA-induced gene activation requires the Argonaute 2 (Ago2) protein and is associated with a loss of lysine-9 methylation on histone 3 at dsRNA-target sites. In conclusion, we have identified several dsRNAs that activate gene expression by targeting noncoding regulatory regions in gene promoters. These findings reveal a more diverse role for small RNA molecules in the regulation of gene expression than previously recognized and identify a potential therapeutic use for dsRNA in targeted gene activation.

Argonaute Proteins↗

PubMed2006

Epigenetic inactivation of the dioxin-responsive cytochrome P4501A1 gene in human prostate cancer.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD; dioxin) is a toxic environmental contaminant that works through dioxin response elements (DRE) to activate gene expression. We tested the hypothesis that cancer-related epigenetic changes suppress dioxin activation of the cytochrome P4501A1 (CYP1A1) gene. 5-Aza-2'-deoxycytidine (5-aza-CdR), an inhibitor of DNA methylation, increases TCDD-inducible CYP1A1 mRNA expression in cancerous LNCaP cells but not in noncancerous PWR-1E and RWPE-1 cells (all human prostate cell lines). Bisulfite DNA sequencing shows that the TCDD-responsive CYP1A1 enhancer is highly methylated in LNCaP cells but not in RWPE-1 cells. In vivo footprinting experiments reveal that unmethylated DRE sites do not bind protein in response to TCDD in LNCaP cells, whereas inducible DRE occupancy occurs in RWPE-1 cells. Pretreatment of LNCaP cells with 5-aza-CdR partially restores TCDD-inducible DRE occupancy, showing that DNA methylation indirectly suppresses DRE occupancy. Chromatin immunoprecipitation experiments reveal that LNCaP cells lack trimethyl histone H3 lysine 4, a mark of active genes, on the CYP1A1 regulatory region, whereas this histone modification is prevalent in PWR-1E and RWPE-1 cells. We also analyzed CYP1A1 enhancer methylation in human prostate tissue DNA. We do not detect CYP1A1 enhancer methylation in 30 DNA samples isolated from noncancerous prostate tissue. In contrast, 11 of 30 prostate tumor DNA samples have detectable CYP1A1 enhancer methylation, indicating that it is hypermethylated in prostate tumors. This is the first report that shows that CYP1A1 is aberrantly hypermethylated in human prostate cancer and has an altered, inaccessible chromatin structure that suppresses its dioxin responsiveness.

Azacitidine↗

PubMed2006

Epigenetic inactivation of Wnt inhibitory factor-1 plays an important role in bladder cancer through aberrant canonical Wnt/beta-catenin signaling pathway.

PURPOSE: Aberrant activation of the Wingless-type (Wnt) pathway plays a significant role in the pathogenesis of several human cancers. Wnt inhibitory factor-1 (Wif-1) was identified as one of the secreted antagonists that can bind Wnt protein. We hypothesize that Wif-1 plays an important role in bladder cancer pathogenesis. EXPERIMENTAL DESIGN: To test this hypothesis, epigenetic and genetic pathways involved in the Wif-1 gene modulation and expression of Wnt/beta-catenin-related genes were analyzed in 4 bladder tumor cell lines and 54 bladder tumor and matched normal bladder mucosa. RESULTS: Wif-1 mRNA expression was significantly enhanced after 5-aza-2'-deoxycytidine treatment in bladder tumor cell lines. Wif-1 promoter methylation level was significantly higher and Wif-1 mRNA expression was significantly lower in bladder tumor samples than in bladder mucosa samples. In the total bladder tumor and bladder mucosa samples, an inverse correlation was found between promoter methylation and Wif-1 mRNA transcript levels. However, loss-of-heterozygosity at chromosome 12q14.3 close to the Wif-1 gene loci was a rare event (3.7%). Nuclear accumulation of beta-catenin was significantly more frequent in bladder tumor than in bladder mucosa and inversely correlated with Wif-1 expression. In addition, known targets of the canonical Wnt/beta-catenin signaling pathway, such as c-myc and cyclin D1, were up-regulated in bladder tumor compared with bladder mucosa, and this up-regulation was associated with reduced Wif-1 expression at both mRNA and protein levels. Furthermore, transfection of Wif-1 small interfering RNA into bladder tumor cells expressing Wif-1 mRNA transcripts had increased levels of c-myc and cyclin D1 and accelerated cell growth. CONCLUSION: This is the first report showing that CpG hypermethylation of the Wif-1 promoter is a frequent event in bladder tumor and may contribute to pathogenesis of bladder cancer through aberrant canonical Wnt/beta-catenin signaling pathway. The present study elucidates novel pathways that are involved in the pathogenesis of bladder cancer.

Adaptor Proteins, Signal Transducing↗

PubMed2006

Smoking influences aberrant CpG hypermethylation of multiple genes in human prostate carcinoma.

BACKGROUND: Aberrant CpG methylation profiles of gene promoters and their correlation with advanced pathologic features have been well investigated in prostate carcinoma (PC). Several case-control and prospective studies have revealed a positive association between current smoking and PC. The authors hypothesized that smoking influences both progression and prognosis of PC through CpG hypermethylation of related genes. METHODS: A total of 164 PC patients (52 current, 30 former, and 82 never smokers) and 69 benign prostatic hyperplasia (BPH) patients were examined by methylation-specific PCR (MSP) for 3 genes: adenomatous polyposis coli (APC), glutathione S-transferase pi (GSTP1), and multidrug resistance one (MDR1). The methylation status of representative samples was confirmed by bisulfite DNA sequencing analysis. The newly defined methylation score (M-score) of each sample is the sum of the corresponding log hazard ratio (HR) coefficients derived from multivariate logistic regression analysis for pathology (BPH vs. PC), and was related to clinical and pathologic outcome including smoking status. RESULTS: The M-score was significantly higher in the current smokers than in never smokers (P = 0.008). Spearman rank correlation test demonstrated a significant correlation between pack-years smoked and M-score in PCs (P = 0.039). Significant correlation of the M-score methylation was observed with high pT category (P < 0.001), high Gleason sum (P < 0.001), high preoperative prostate-specific antigen (PSA) (P = 0.041), and advanced pathologic features. In addition, Gleason sum was significantly associated with PSA failure-free probability as a poor outcome (P = 0.020). CONCLUSIONS: This is the first study to demonstrate significant correlation of the methylation status of multigenes with smoking status in PC. Smoking status may influence both progression and prognosis of PC through CpG hypermethylation of related genes.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2006

The E-cadherin -160 C/A polymorphism and prostate cancer risk in white and black American men.

PURPOSE: We have previously reported that a C/A single nucleotide polymorphism at position -160 of the human E-cadherin gene promoter affects E-cadherin transcription. Although this single nucleotide polymorphism is associated with a number of human cancers, including prostate cancer, it is not known whether it has a role in race related prostate cancer. We hypothesized that allelic variation at this site may be associated with racial differences in the incidence and severity of prostate cancer. MATERIALS AND METHODS: We analyzed the genotypes of this single nucleotide polymorphism in a total of 135 prostate cancer samples from 86 white and 49 black American men, and in 237 samples from normal healthy controls, including 120 white and 117 black men, using the polymerase chain reaction-restriction fragment length polymorphism technique. RESULTS: Of normal controls black men had a higher frequency of the A allele and CA genotype than white men (26.5 and 39.3 vs 22.5 and 28.3, respectively). In white men A allele frequency was significantly higher in those with prostate cancer than in controls (p <0.05). White men carrying the A allele and AA genotype were at 1.99-fold (95% CI 1.29 to 3.08) and 3.04-fold (95% CI 1.26 to 7.32) higher risk for prostate cancer than carriers of the C allele and CC genotype. However, in black men the A allele was more frequent in controls than in patients with cancer and it was associated with a 2.4-fold decrease in prostate cancer risk (95% CI 0.22 to 0.81) compared to the C allele. CONCLUSIONS: The A allele of the E-cadherin -160 single nucleotide polymorphism represents a prostate cancer risk factor in white but not in black men.

Black or African American↗

PubMed2005

Multigene methylation analysis for detection and staging of prostate cancer.

PURPOSE: Aberrant gene promoter methylation profiles have been well-studied in human prostate cancer. Therefore, we rationalize that multigene methylation analysis could be useful as a diagnostic biomarker. We hypothesize that a new method of multigene methylation analysis could be a good diagnostic and staging biomarker for prostate cancer. EXPERIMENTAL DESIGN: To test our hypothesis, prostate cancer samples (170) and benign prostatic hyperplasia samples (69) were examined by methylation-specific PCR for three genes: adenomatous polyposis coli (APC), glutathione S-transferase pi (GSTP1), and multidrug resistance 1 (MDR1). The methylation status of representative samples was confirmed by bisulfite DNA sequencing analysis. We further investigated whether methylation score (M score) can be used as a diagnostic and staging biomarker for prostate cancer. The M score of each sample was calculated as the sum of the corresponding log hazard ratio coefficients derived from multivariate logistic regression analysis of methylation status of various genes for benign prostatic hyperplasia and prostate cancer. The optimal sensitivity and specificity of the M score for diagnosis and for staging of prostate cancer was determined by receiver-operator characteristic (ROC) curve analysis. A pairwise comparison was employed to test for significance using the area under the ROC curve analysis. For each clinicopathologic finding, the association with prostate-specific antigen (PSA) failure-free probability was determined using Kaplan-Meier curves and a log-rank test was used to determine significance. The relationship between M score and clinicopathologic findings was analyzed by either the Mann-Whitney U test, Kruskal-Wallis test, or the Spearman rank correlation test. RESULTS: The frequency of positive methylation-specific PCR bands for APC, GSTP1, and MDR1 genes in prostate cancer samples was 64.1%, 54.0%, and 55.3%, respectively. In benign prostatic hyperplasia samples, it was 8.7%, 5.8%, and 11.6%, respectively. There was a significant correlation of M score with high pT category (P < 0.001), high Gleason sum (P < 0.001), high preoperative PSA (P = 0.027), and advanced pathologic features. For all patients, the M score had a sensitivity of 75.9% and a specificity of 84.1% as a diagnostic biomarker using a cutoff value of 1.0. In patients with low or borderline PSA levels (<10.0 ng/mL), the M score was significantly higher in prostate cancers than in benign prostatic hyperplasias (2.635 +/- 0.200 and 0.357 +/- 0.121, respectively). ROC curve analysis revealed that the M score had a sensitivity of 65.4% and a specificity of 94.2% when 1.0 was used as a cutoff value. For all patients, M score can distinguish organ-confined (< or =pT(2)) from locally advanced cancer (> or =pT(3)) with a sensitivity of 72.1% and a specificity of 67.8%. Moreover, considering patients with PSA levels of <10 ng/mL, the M score has a sensitivity of 67.1% and a specificity of 85.7%. The ROC curve analysis showed a significant difference between M score and PSA (P = 0.010). CONCLUSIONS: This is the first report demonstrating that M score is a new method for multigene methylation analysis that can serve as a good diagnostic and staging biomarker for prostate cancer.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2005

Ethnic group-related differences in CpG hypermethylation of the GSTP1 gene promoter among African-American, Caucasian and Asian patients with prostate cancer.

The incidence and mortality of prostate cancer (PC) is approximately 2-fold higher among African-Americans as compared to Caucasians and very low in Asian. We hypothesize that inactivation of GSTP1 genes through CpG methylation plays a role in the pathogenesis of PC, and its ability to serve as a diagnostic marker that differs among ethnic groups. GSTP1 promoter hypermethylation and its correlation with clinico-pathological findings were evaluated in 291 PC (Asian = 170; African-American = 44; Caucasian = 77) and 172 benign prostate hypertrophy samples (BPH) (Asian = 96; African-American = 38; Caucasian = 38) using methylation-specific PCR. In PC cells, 5-aza-dC treatment increased expression of GSTP1 mRNA transcripts. The methylation of all CpG sites was found in 191 of 291 PC (65.6%), but only in 34 of 139 BPH (24.5%). The GSTP1 hypermethylation was significantly higher in PC as compared to BPH in each ethnic group (p < 0.0001). Logistic regression analysis (PC vs. BPH) showed that African-Americans had a higher hazard ratio (HR) (13.361) compared to Caucasians (3.829) and Asian (8.603). Chi-square analysis showed correlation of GSTP1 hypermethylation with pathological findings (pT categories and higher Gleason sum) in Asian PC (p < 0.0001) but not in African-Americans and Caucasian PC. Our results suggest that GSTP1 hypermethylation is a sensitive biomarker in African-Americans as compared to that in Caucasians or Asian, and that it strongly influences tumor progression in Asian PC. Ours is the first study investigating GSTP1 methylation differences in PC among African-American, Caucasian and Asian.

Adult↗

PubMed2005

Cytochrome P450 1B1 is overexpressed and regulated by hypomethylation in prostate cancer.

PURPOSE: Cytochrome P450 1B1 (CYP1B1), a dioxin inducible member of the CYP supergene family, is overexpressed in various human malignancies including prostate cancer. We hypothesized that promoter/enhancer CpG methylation contributes to the regulation of CYP1B1 expression in human prostate tissue. EXPERIMENTAL DESIGN: Expression and induction of the CYP1B1 gene in clinical prostate tissues and prostate cancer cell lines were investigated. The methylation status of the CYP1B1 gene was analyzed in 175 prostate cancer and 96 benign prostatic hyperplasia samples using methylation-specific PCR (MSP) and bisulfite-modified DNA sequencing. MSP primers covered dioxin response elements (DRE) and Sp1 sites that are important for the expression of CYP1B1. RESULTS: Expressions of CYP1B1 mRNA and protein were increased in prostate cancer. The aryl hydrocarbon receptor (AhR)/AhR nuclear translocator (ARNT) heterodimer complex activates gene transcription by binding to the DREs of CYP1B1. In prostate cancer cells, CYP1B1 mRNA was induced by 2,3,7,8-tetrachlorodigenzo-p-dioxin (TCDD) and/or demethylation agent (5-aza-2-deoxycytidine). There was no change in the expressions of AhR and ARNT. Methylation of promoter/enhancer regions was significantly higher in benign prostatic hyperplasia compared with prostate cancer. MSP-positive patients had significantly lower risk for prostate cancer as compared with MSP-negative patients. There was no correlation between CYP1B1 methylation status and clinicopathologic features. CONCLUSIONS: CYP1B1 is overexpressed in prostate cancer and regulated by hypomethylation of its promoter/enhancer region. This is the first report about CYP1B1 regulation in human clinical prostate samples showing that hypomethylation of the CYP1B1 gene may play an important role in prostate cancer.

Aged↗

PubMed2005

CpG methylation at promoter site -140 inactivates TGFbeta2 receptor gene in prostate cancer.

BACKGROUND: The action of transforming growth factor beta (TGF-beta) is mediated through type 1 (TbetaRI) and type 2 (TbetaRII) receptors. Prostate cancer cells are often resistant to TGF-beta signaling due to loss of TbetaRII expression. The authors of the current study hypothesized that CpG methylation of the TbetaRII promoter at the Sp1 binding site -140 mediates this loss of TbetaRII expression in prostate cancer. METHODS: Sixty-seven prostate cancer (PC) samples, 8 benign prostatic hyperplasia (BPH) samples, and 4 prostate cancer cell lines (DUPro, LNCaP, ND-1 and PC-3) were analyzed for 1) TbetaRII mRNA expression by semiquantitative RT-PCR, 2) TbetaRII protein expression by immunohistochemistry, and 3) TGFbetaRII promoter methylation at CpG site -140 by methylation specific PCR and bisulfite DNA sequencing. Prostate cancer cell lines were treated with the demethylating agent 5aza2'deoxycytidine to determine if TbetaRII gene expression could be increased by blocking promoter methylation. RESULTS: mRNA and protein expression of TbetaRII was lower in the PC samples than in the BPH samples. CpG methylation at site -140 was higher in PC than in BPH (P < 0.01). Promoter methylation was inversely correlated with TbetaRII mRNA expression in the PC and BPH samples (P < 0.0001). PC3, ND1, and DUPro TbetaRII mRNA expression increased following treatment of cells with 5-aza-2'-deoxycytidine. CONCLUSION: CpG methylation of the TbetaRII promoter at CPG site -140 leads to functional loss of the TbetaRII gene in prostate cancer. Treatment with 5-aza-2' deoxycytidine can restore gene expression. The current study results report the first association between prostate cancer and loss of the TGF- beta signaling pathway by TbetaRII DNA promoter methylation.

Azacitidine↗

PubMed2005

Functional Loss of the gamma-catenin gene through epigenetic and genetic pathways in human prostate cancer.

Gamma-catenin is a cell adhesion molecule and a candidate mediator of Wnt signal transduction. We hypothesized that impaired regulation of gamma-catenin through genetic and epigenetic pathways is associated with the pathogenesis of prostate cancer. To test this hypothesis, cytosine-phosphate-guanine methylation, loss of heterozygosity (LOH), and mutation status of the gamma-catenin gene were analyzed in cultured prostate cancer cell lines, 180 localized prostate cancers, 69 benign prostatic hyperplasias, and 11 hormone refractory prostate cancers (HRPC). In prostate cancer cell lines (DuPro, LNCaP, ND-1, and PC3), gamma-catenin mRNA transcripts were increased after 5-aza-2'-deoxycytidine treatment. In localized prostate cancer, gamma-catenin expression was lower but prevalence of gamma-catenin methylation was higher compared with benign prostatic hyperplasia. However, gamma-catenin methylation did not correlate with Gleason sum, pT category, or capsular penetration. Among localized prostate cancers with positive gamma-catenin methylation, the presence of LOH at chromosome 17q21 was closely related to down-regulation of gamma-catenin mRNA expression. The gamma-catenin mutations were not found in localized prostate cancers, whereas six mutations were found in five HRPCs within or close to the GSK-3beta consensus motif phosphorylation site, among which four HRPCs showed strong nuclear gamma-catenin accumulation. In these four HRPCs, Bcl-2 expression was increased, whereas the target of the Wnt signal, c-myc, was only expressed in one HRPC. Therefore, although epigenetic gamma-catenin methylation is an early event in the development of prostate cancer, simultaneous events of epigenetic cytosine-phosphate-guanine methylation and genetic LOH may be responsible for functional loss of gamma-catenin. The gamma-catenin mutation related to Bcl-2 overexpression has a significant effect on the pathogenesis of HRPC. This is the first report to characterize the epigenetic and genetic regulation of gamma-catenin in human prostate cancer.

Amino Acid Sequence↗

PubMed2005

Increased heparanase expression is caused by promoter hypomethylation and up-regulation of transcriptional factor early growth response-1 in human prostate cancer.

PURPOSE: Heparanase degrades heparan sulfate and has been implicated in tumor invasion and metastasis. The transcription factor, early growth response 1 (EGR1), is associated with the inducible transcription of the heparanase gene. We hypothesize that CpG hypomethylation in the heparanase promoter coupled with up-regulation of EGR1 levels may induce heparanase expression in human prostate cancer. EXPERIMENTAL DESIGN: Cultured prostate cancer cell lines (Du145, DuPro, LNCaP, and PC-3) with and without 5'-aza-2-deoxycytidine treatment, 177 prostate cancer samples, and 69 benign prostatic hyperplasia (BPH) samples were used. The frequency and level of heparanase promoter methylation were analyzed by methylation-specific primers which covered the core binding motif of EGR1 (GGCG) or SP1 (GGGCGG) or both. RESULTS: In cultured Du145, DuPro, LNCaP, and PC-3 cell lines, mRNA transcripts of heparanase were significantly increased after 5'-aza-2-deoxycytidine treatment, suggesting that promoter methylation was involved in the regulation of heparanase mRNA transcript. Significantly higher methylation was found in BPH samples than in prostate cancer samples (P < 0.0001), whereas mRNA transcripts of the heparanase gene were inversely lower in BPH samples than in prostate cancer samples (P < 0.01). EGR1 expression in prostate cancer tissues was significantly higher than in BPH tissues (P < 0.001) and correlated with heparanase expression (P < 0.0001). Moreover, multiple regression analysis revealed that up-regulation of EGR1 contributed significantly more to heparanase expression than did promoter CpG hypomethylation in prostate cancer samples (P < 0.0001). CONCLUSIONS: To our knowledge this is the first comprehensive study demonstrating that increased heparanase expression in prostate cancer tissues is due to promoter hypomethylation and up-regulation of transcription factor EGR1.

Aged↗

PubMed2005

Epigenetic changes in prostate cancer: implication for diagnosis and treatment.

Prostate cancer is the most common noncutaneous malignancy and the second leading cause of cancer death among men in the United States. DNA methylation and histone modifications are important epigenetic mechanisms of gene regulation and play essential roles both independently and cooperatively in tumor initiation and progression. Aberrant epigenetic events such as DNA hypo- and hypermethylation and altered histone acetylation have both been observed in prostate cancer, in which they affect a large number of genes. Although the list of aberrantly epigenetically regulated genes continues to grow, only a few genes have, so far, given promising results as potential tumor biomarkers for early diagnosis and risk assessment of prostate cancer. Thus, large-scale screening of aberrant epigenetic events such as DNA hypermethylation is needed to identify prostate cancer-specific epigenetic fingerprints. The reversibility of epigenetic aberrations has made them attractive targets for cancer treatment with modulators that demethylate DNA and inhibit histone deacetylases, leading to reactivation of silenced genes. More studies into the mechanism and consequence of demethylation are required before the cancer epigenome can be safely manipulated with therapeutics as a treatment modality. In this review, we examine the current literature on epigenetic changes in prostate cancer and discuss the clinical potential of cancer epigenetics for the diagnosis and treatment of this disease.

Acyltransferases↗

PubMed2005

Retroperitoneal laparoscopic nephron-sparing surgery for renal tumors: report of 32 cases.

OBJECTIVES: To evaluate the feasibility and clinical efficacy of retroperitoneal laparoscopic nephron-sparing surgery for renal tumors. METHODS: Between June 2002 and February 2004, 11 cases of renal benign tumor and 21 cases of renal malignant tumor underwent enucleation of the tumor and wedge resection of the tumor through retroperitoneal laparoscopy, respectively. Tumor resection and hemostasis were mainly achieved by harmonic scalpel. Follow-up studies were performed with an evaluation using renal spiral computed tomography. RESULTS: All procedures were technically successful. The mean operating time was 70 minutes for enucleation and 96 minutes for wedge resection. The mean estimated blood loss was 35 mL for enucleation and 65.5 mL for wedge resection. The mean hospital stay after surgery was 6.5 days. No intraoperative complications occurred. The pathologic examination confirmed renal cell carcinoma in 21 patients and angiomyolipoma in 11. The pathologic stage was pT1a in the 21 patients with renal cell carcinoma. All resected tumor specimens had negative surgical margins for cancer. No local recurrence or trocar site metastasis was observed during a mean follow-up period of 13 months. CONCLUSIONS: Our results indicate that retroperitoneal laparoscopic nephron-sparing surgery represents a feasible option for patients with localized renal tumors. This procedure could offer precise and complete tumor excision while minimizing morbidity, improving cosmesis, and shortening convalescence.

Adult↗

PubMed2005

Comparison of retroperitoneoscopic nephrectomy versus open approaches to nonfunctioning tuberculous kidneys: a report of 44 cases.

PURPOSE: We retrospectively investigated the advantages of retroperitoneoscopic nephrectomy for nonfunctioning tuberculous kidneys by comparing its clinical results, operative methods and skills with those of open nephrectomy. MATERIALS AND METHODS: Clinical data on 22 patients with nonfunctioning tuberculous kidneys who underwent retroperitoneoscopic nephrectomy, including simple and subcapsular nephrectomy, were compared with those on 22 who underwent open nephrectomy for a similar indication during the same period. Results in the 2 groups were analyzed. RESULTS: There was no statistical difference between the retroperitoneoscopy and open surgery groups with regard to patient age, sex or mean operative time +/- SD (93.0 +/- 12.6 vs 92.6 +/- 35.5 minutes). Mean blood loss was significantly less in the retroperitoneoscopy group than in the open surgery group (78.3 +/- 60.6 vs 160 +/- 120.0 ml). Mean hospital stay after operation was notably shorter in the retroperitoneoscopy group compared with the open surgery group (3.3 +/- 0.9 vs 9.1 +/- 0.8 days). The mean analgesic requirement for opioids and diclofenac sodium was also lower in the retroperitoneoscopy group than in the open surgery group (0 vs 2.1 +/- 0.9 and 5.2 +/- 1.1 vs 5.8 +/- 1.3 doses, respectively). CONCLUSIONS: Retroperitoneoscopic nephrectomy for renal tuberculosis has several advantages over open nephrectomy, namely a smaller wound, less blood loss and more rapid recovery. It may provide a safe and reliable method for treating refractory renal tuberculosis clinically.

Adult↗

PubMed2004

DNA methylation in prostate cancer.

Prostate cancer is the most common malignancy and the second leading cause of cancer death among men in the United States. There are three well-established risk factors for prostate cancer: age, race and family history. The molecular bases for these risk factors are unclear; however, they may be influenced by epigenetic events. Epigenetic events covalently modify chromatin and alter gene expression. Methylation of cytosine residues within CpG islands on gene promoters is a primary epigenetic event that acts to suppress gene expression. In tumorigenesis, the normal functioning of the epigenetic-regulatory system is disrupted leading to inappropriate CpG island hypermethylation and aberrant expression of a battery of genes involved in critical cellular processes. Cancer-dependent epigenetic regulation of genes involved in DNA damage repair, hormone response, cell cycle control and tumor-cell adhesion/metastasis can contribute significantly to tumor initiation, progression and metastasis and, thereby, increase prostate cancer susceptibility and risk. In this review, we will discuss current research on genes that are hypermethylated in human prostate cancer. We will also discuss the potential involvement of DNA methylation in age-related, race-related and hereditary prostate cancer, and the potential use of hypermethylated genes as biomarkers to detect prostate cancer and assess its risk.

Age Factors↗

PubMed2004

CpG hypermethylation of MDR1 gene contributes to the pathogenesis and progression of human prostate cancer.

Multidrug resistance 1 (MDR1) gene encodes for P-glycoprotein (P-gp), a Mr 170,000 transmembrane calcium-dependent efflux pump that is inactivated in prostate cancer. We hypothesize that inactivation of the MDR1 gene through CpG methylation contributes to the pathogenesis and progression of prostate cancer. To test this hypothesis, CpG methylation status of the MDR1 promoter and its correlation with clinicopathological findings were evaluated in 177 prostate cancer samples and 69 benign prostate hypertrophy (BPH) samples. Cellular proliferation index and apoptotic index were determined by proliferating cell nuclear antigen (PCNA) and single-strand DNA immunostaining, respectively. After 5-aza-2'-deoxycytidine treatment, increased expression of MDR1 mRNA transcript was found in prostate cancer cell lines (DU145, DuPro, and ND1). MDR1 methylation frequency was significantly higher in prostate cancer samples compared with BPH samples (54.8 versus 11.6%, respectively, P < 0.001). Logistic regression analysis revealed that PC patients are 11.5 times more likely to have MDR1 methylation than BPH patients (95% confidence interval 4.87-27.0) and that MDR1 methylation is independent of the age. Significant correlation of MDR1 methylation was observed with high pT category (P < 0.001), high Gleason sum (P = 0.008), high preoperative prostate-specific antigen (P = 0.01), and advancing pathological features. In addition, PCNA-labeling index were significantly higher in methylation-specific PCR (MSP)-positive than in MSP-negative prostate cancer samples (P = 0.048). In contrast, no significant difference in apoptotic index was found between MSP-positive and -negative prostate cancer samples. These findings suggest that CpG hypermethylation of MDR1 promoter is a frequent event in prostate cancer and is related to disease progression via increased cell proliferation in prostate cancer cells.

Aged↗

PubMed2004

Age-dependent methylation of ESR1 gene in prostate cancer.

The incidence of prostate cancer increases dramatically with age and the mechanism underlying this association is unclear. Age-dependent methylation of estrogen receptor alpha (ESR1) gene has been previously implicated in other cancerous and benign diseases. We evaluated the age-dependent methylation of ESR1 in prostate cancer. The methylation status of ESR1 in 83 prostate cancer samples from patients aged 49 to 77 years (mean age at 67.4 years) was examined using the bisulfite genomic sequencing technique. The samples were divided into three age groups: men aged 60 years and under (n = 14), men aged 61-70 years (n = 40), and men aged over 70 years (n = 29). Overall, ESR1 promoter methylation was detected in 54 out of 83 (65.1%) prostate samples. The methylation rate of ESR1 increased dramatically with age from 50.0% in patients aged 60 years and under to 89.7% for patients aged 70 years and over. Logistic regression analyses revealed that age and Gleason score were the only variables that affect incidence of ESR1 methylation; other clinical factors such as prostate-specific antigen level and clinical stage did not. We also calculated ESR1 methylation density (the percentage of methylated CpGs among all CpGs within the analyzed region) and severity (the percentage of methylated CpG alleles) for each sample analyzed. Multiple regression analyses showed a positive correlation between age and methylation density (beta, 0.35; P, 0.012; 95% CI, 0.26-2.01); while Gleason score was positively associated with methylation severity (beta, 0.45; P, 0.018; 95% CI, 1.04-4.26). These findings suggest that methylation of ESR1 is both age-dependent and tumor differentiation-dependent and age-dependent methylation of ESR1 may represent a mechanism linking aging and prostate cancer.

Aged↗

PubMed2004

Kidney gene database: a curated and integrated database of genes involved in kidney disease.

PURPOSE: We have created a curated and integrated database, the Kidney Gene Database (KGDB) (http://www.urogene.org/kgdb) that contains current information about genes or genomic loci involved in human kidney disease. MATERIALS AND METHODS: Genes that undergo molecular, genetic or epigenetic events that affect kidney function are identified through a biomedical literature search and catalogued in the database. RESULTS: Events that are currently screened for are gene amplification, mutation, deletion, polymorphism, loss of heterozygosity, DNA methylation and DNA hypomethylation. In addition, genes that are uniquely expressed in the kidney, as determined by analyzing the expressed sequence tags database and the Serial Analysis of Gene Expression database, are also included in KGDB. For each gene KGDB provides basic information about the gene product, a tissue type gene expression profile, links to protein, mRNA and genomic DNA sequence information, relevant literature citations and cross-references to other databases. CONCLUSIONS: We present KGDB, which is to our knowledge the first curated and integrated database of genes involved in human kidney disease. KGDB is free, widely accessible and easy to use, and it provides a wealth of relevant information. In addition, KGDB will be continuously updated every 6 months to include new information published in the biomedical literature or in gene expression databases. We envision that KGDB will serve as a valuable resource for scientists and clinicians.

Databases, Genetic↗