Molecular Diagnostic of Prostate Cancer From Body Fluids Using Methylation-Specific PCR (MS-PCR) Method

BACKGROUND

Worldwide prostate cancer (PCa) represents the 2nd leading cause of cancer related deaths among men. Currently, the screening for early detection of PCa is based on determination of serum prostate-specific antigen (PSA) levels. But this biomarker presents some disadvantages related to its specificity and sensitivity. In our study, we want to determine if methylation levels of the glutathione S-transferase P1 (GSTP1) gene could be used as a new biomarker for the early detection of PCa and to distinguish between malignant and benign pros-tatic lesions.

METHODS

To determine the methylation levels of the GSTP1 gene, 31 men with histopathological diagnosis of prostate adenocarcinoma and 34 men with the histopathological diagnosis of benign prostatic hyperplasia (BPH) as controls were included in the study group. The genomic DNA was extracted from urine samples. We analyzed the methylation levels of the GSTP1 gene by methylation-specific polymerase chain reaction (MS-PCR) method.

RESULTS

In prostate cancer patients 27 of 31 (87%) presented hypermethylated levels of the GSTP1 gene, whereas 4 of 34 (11.8%) BPH patients had hypermethylated levels of the GSTP1 gene. Further, in the case of these four patients a second biopsy was done, which confirmed the diagnosis of prostate adenocarcinoma. Using the receiver operating curve (ROC), we obtained a specificity of 87% and a sensitivity of 98% for the GSTP1 gene.

CONCLUSIONS

We can conclude that GSTP1 represents a new molecular biomarker which can aid in early detection of PCa and be used to discriminate between benign and malignant prostatic lesions from body fluids by noninvasive methods.

Study of genetic and epigenetic alterations in urine samples as diagnostic markers for prostate cancer

BACKGROUND

Early diagnosis of prostate cancer and identification of new prognostic factors remain main issues in prostate cancer research. In this study, we sought to test a panel of cancer-specific markers in urine samples as an aid for early cancer diagnosis.

MATERIALS AND METHODS

Sedimented urine samples of 66 candidates for needle biopsy were tested. Real time-polymerase chain reaction (RT-PCR) was applied to detect the expression of transmembrane protease serine-2 and Ets-related gene fusion (TMPRSS2-ERG), Ets-related gene (ERG), prostate cancer antigen-3 (PCA3), and serine peptidase inhibitor kazal type-1 (SPINK1) transcripts. For testing of the methylation status of Glutahione S-tranferase P (GSTP1) and Ras association domain family member-1(RASSF1A) promoter region, methylation-specific PCR (MSP-PCR) was applied.

RESULTS

Among the tested parameters, the presence of TMPRSS2-ERG (OR=9.044, 95% CI=2.207-37.066, p=0.002), as well as a positive test result for PCA3 (OR=7.549, 95% CI=1,858-30,672, p=0.005) were associated with the subsequent diagnosis of prostate cancer. A multivariable logistic regression including all the significantly associated variables [prostate-specific antigen (PSA), digital rectal examination (DRE), TMPRSS2-ERG and PCA3], yielded a model with area under the receiver-operating characteristic curve (AUC) =0.894 (95% CI=0.772-1.00).

CONCLUSION

A multiplexed quantitative PCR analysis on sedimented urine, in conjunction with the results of serum PSA levels and DRE, has the potential to accurately foresee subsequent needle biopsy outcomes. On the basis of the above, algorithms may be designed to guide decisions for needle biopsy.

Glutathione enzyme and selenoprotein polymorphisms associate with mercury biomarker levels in Michigan dental professionals

Mercury is a potent toxicant of concern to both the general public and occupationally exposed workers (e.g., dentists). Recent studies suggest that several genes mediating the toxicokinetics of mercury are polymorphic in humans and may influence inter-individual variability in mercury accumulation. This work hypothesizes that polymorphisms in key glutathione synthesizing enzyme, glutathione S-transferase, and selenoprotein genes underlie inter-individual differences in mercury body burden as assessed by analytical mercury measurement in urine and hair, biomarkers of elemental mercury and methylmercury, respectively. Urine and hair samples were collected from a population of dental professionals (n=515), and total mercury content was measured. Average urine (1.06±1.24 microg/L) and hair mercury levels (0.49±0.63 microg/g) were similar to national U.S. population averages. Taqman assays were used to genotype DNA from buccal swab samples at 15 polymorphic sites in genes implicated in mercury metabolism. Linear regression modeling assessed the ability of polymorphisms to modify the relationship between mercury biomarker levels and exposure sources (e.g., amalgams, fish consumption). Five polymorphisms were significantly associated with urine mercury levels (GSTT1 deletion), hair mercury levels (GSTP1-105, GSTP1-114, GSS 5'), or both (SEPP1 3'UTR). Overall, this study suggests that polymorphisms in selenoproteins and glutathione-related genes may influence elimination of mercury in the urine and hair or mercury retention following exposures to elemental mercury (via dental amalgams) and methylmercury (via fish consumption).

Frequent methylation of RASSF1 and RARB in urine sediments from patients with early stage prostate cancer

BACKGROUND. Prostate cancer (PCa) is the second most prevalent malignancy among males, characterized by high mortality rates. Aberrant DNA methylation in promoters of tumor suppressor genes is an early and frequent event during prostate carcinogenesis. Modern techniques allow a sensitive detection of DNA methylation biomarkers in bodily fluids from cancer patients offering a noninvasive tool for PCa monitoring. Our study aimed at the analysis of DNA methylation in urine sediments from PCa patients for the selection of most informative noninvasive biomarkers. MATERIAL AND METHODS. Real-time methylation-specific polymerase chain reaction was used for the detection of methylated RASSF1, RARB, and GSTP1 genes in catheterized urine specimens from 34 patients with biopsy-proven early or medium stage PCa. RESULTS. At least one gene was methylated in urine sediments from 28 cases with PCa, with a sensitivity of the test reaching 82%. RASSF1 was methylated in 71% (24 of 34), RARB in 44% (15 of 34), and GSTP1 in 3% (1 of 34) of the specimens. High level of methylation (≥50%) in RARB and RASSF1 genes was detected in 40% and 20% of cases, respectively. A significant association was observed between high level of RARB methylation and Gleason score (P=0.01), while methylation of at least one gene occurred more frequently in urine DNA of older patients (P=0.02). CONCLUSIONS. Results of our study show a high sensitivity of DNA methylation biomarkers, especially RASSF1 and RARB, for the early and noninvasive detection of PCa.

Urinary collagen IV and πGST: potential biomarkers for detecting localized kidney injury in diabetes--a pilot study

BACKGROUND/AIMS

Urinary biomarkers can identify damage to specific parts of the nephron. We performed a cross-sectional study to characterise the pattern of diabetic nephropathy using urinary biomarkers of glomerular fibrosis (collagen IV), proximal tubular damage (α-glutathione-S-transferase, GST) and distal tubular damage (πGST).

METHODS

Clinical data from 457 unselected patients attending a hospital diabetes clinic were collected. Spot urine samples were analysed for albumin and creatinine. Biomarkers were measured by enzyme-linked immunosorbent assay, and corrected to urinary creatinine.

RESULTS

All 3 biomarkers correlated weakly with albumin/creatinine ratios (Pearson correlation <0.2, p values <0.001). The most common abnormality was elevated urinary collagen IV (glomerular, 35%) compared to αGST (proximal tubule, 18%) or πGST (distal tubule, 15%). The proportion of patients with abnormal biomarker results increased across the normo-, micro- and macroalbuminuria groups, with collagen IV (26, 58, 65%) and πGST (11, 25, 35%) but not αGST.

CONCLUSION

In patients with diabetes, these urinary biomarkers appear to identify renal damage that is related to, but distinct from, urine albumin/creatinine ratios. The markers of glomerular fibrosis and distal tubular damage related most closely to the degree of albuminuria. Longitudinal studies are now required to assess whether these biomarkers can detect early renal disease with greater specificity and sensitivity than the albumin/creatinine ratio.

DNA methylation biomarkers of prostate cancer: confirmation of candidates and evidence urine is the most sensitive body fluid for non-invasive detection

BACKGROUND

A prostate cancer (PCa) biomarker with improved specificity relative to PSA is a public health priority. Hypermethylated DNA can be detected in body fluids from PCa patients and may be a useful biomarker, although clinical performance varies between studies. We investigated the performance of candidate PCa DNA methylation biomarkers identified through a genome-wide search.

METHODS

Real-time PCR was used to measure four DNA methylation biomarkers: GSTP1 and three previously unreported candidates associated with the genes RASSF2, HIST1H4K, and TFAP2E in sodium bisulfite-modified DNA. Matched plasma and urine collected prospectively from 142 patients referred for prostate biopsy and 50 young asymptomatic males were analyzed.

RESULTS

Analysis of all biomarkers in urine DNA significantly discriminated PCa from biopsy negative patients. The biomarkers discriminated PCa from biopsy negative patients with AUCs ranging from 0.64 for HIST1H4K (95% CI 0.55-0.72, P < 0.00001) to 0.69 for GSTP1 (95% CI 0.60-0.77, P < 0.00001). All biomarkers showed minimal correlation with PSA. Multivariate analysis did not yield a panel that significantly improved performance over that of single biomarkers. All biomarkers showed greater sensitivity for PCa in urine than in plasma DNA.

CONCLUSIONS

Analysis of the biomarkers in urine DNA significantly discriminated PCa from biopsy negative patients. The biomarkers provided information independent of PSA and may warrant inclusion in nomograms for predicting prostate biopsy outcome. The biomarkers' PCa sensitivity was greater for urine than plasma DNA. The biomarker performances in urine DNA should next be validated in formal training and test studies.

[Prospects for diagnosis of prostate cancer by biomarkers in the urine]

Prostate cancer is the most frequently diagnosed cancer in the Western male population and the second leading cause of cancer mortality. Recently many new methods are used to detect the tumor, some of which use the urine as the sample. The biomarkers in the urine will possibly improve the sensitivity and specificity to aid in prostate cancer detection.

Quantitation of glutathione S transferase-pi in the urine of preterm neonates

BACKGROUND

Glutathione S transferases (GSTs) are widely distributed enzymes found in highly varying amounts in tissues of the human body. The enzyme GST-pi in urine has been used as a marker of renal distal tubular cell damage. The present study was intended to evaluate urinary excretion of GST-pi and its relationship to other renal markers and to the status of oxidative stress in preterm neonates.

METHODS

Levels of urinary GST-pi, N-acetyl-beta-glucosaminidase (a marker of proximal tubular damage), albumin (a marker of glomerular damage) and 8-hydroxy-2'-deoxyguanosine (a marker of oxidative stress) and serum creatinine were measured in preterm neonates at 1 and 4 weeks of age.

RESULTS

The results showed that urinary excretion of GST-pi is increased in preterm neonates compared with reported values for healthy adults. No significant relationship was detected between urinary GST-pi and other markers for renal function. Urinary GST-pi showed significantly positive correlation with urinary 8-hydroxy-2'-deoxyguanosine at 1 and 4 weeks. Sick neonates treated with supplemental oxygen and mechanical ventilation showed significantly higher levels of GST-pi as well as 8-hydroxy-2'-deoxyguanosine than clinically stable neonates did at 4 weeks.

CONCLUSIONS

These results indicate the potential effect of systemic oxidative stress on urinary excretion of GST-pi. Further studies are necessary to explore the effect of oxidative conditions on expression of GST-pi in distal tubules in the human kidney.

Urinary GSTP1-1 excretion is markedly increased in normotensive pregnancy as well as in preeclampsia

BACKGROUND

Glutathione S-transferases (GSTs) are present in large amounts in the human kidney, where they demonstrate a specific distribution. The assessment of urinary excretion of GST alpha (proximal tubules) and pi (distal and collecting tubules) could be helpful in determining if, and to what degree renal tubular damage is present in preeclampsia and whether this damage is in the proximal or distal region.

METHODS

Urine samples were collected from 22 women with severe preeclampsia and/or HELLP syndrome (PE), from 30 non-pregnant women with a history of severe preeclampsia (HPE), from 18 women with uncomplicated pregnancies (PC) and from 30 non-pregnant women with a history of uncomplicated pregnancies (HPC). GSTA1-1 and GSTP1-1 were assayed by ELISA and were expressed as nanograms per 10 mmol creatinine (Cr).

RESULTS

Median urinary GSTP1-1 concentrations were significantly (p<0.001) higher in women with preeclampsia [62.2 (4.3-291.2) ng/10 mmol Cr] compared to non-pregnant women with a history of preeclampsia [22.3 (0-142.6) ng/10 mmol Cr]). In addition, in normotensive pregnant women, urinary GSTP1-1 concentrations were significantly (p<0.01) higher [82.6 (8.3-206.7) ng/10 mmol Cr]) compared to non-pregnant controls [5.1 (0-66.7) ng/10 mmol Cr]. No difference in GSTP1-1 concentrations was found between women with preeclampsia and normotensive pregnant women. GSTA1-1 concentrations were not significantly different between the four groups of women investigated. There were no correlations between the degree of proteinuria and urinary GSTP1-1 or GSTA1-1 concentrations.

CONCLUSION

GSTP1-1 metabolism in the distal tubule changes during normotensive as well as preeclamptic pregnancy. Whether this is due to tubular cell damage, disturbed resorption or an increase in cellular levels cannot be determined as yet.