Use of the MyProstateScore Test to Rule Out Clinically Significant Cancer: Validation of a Straightforward Clinical Testing Approach.

PURPOSE: The MyProstateScore test was validated for improved detection of clinically significant (grade group ≥2) prostate cancer relative to prostate specific antigen based risk calculators. We sought to validate an optimal MyProstateScore threshold for clinical use in ruling out grade group ≥2 cancer in men referred for biopsy. MATERIALS AND METHODS: Biopsy naïve men provided post-digital rectal examination urine prior to biopsy. MyProstateScore was calculated using the validated, locked multivariable model including only serum prostate specific antigen, urinary prostate cancer antigen 3 and urinary TMPRSS2:ERG. The MyProstateScore threshold approximating 95% sensitivity for grade group ≥2 cancer was identified in a training cohort, and performance was measured in 2 external validation cohorts. We assessed the 1) overall biopsy referral population and 2) population meeting guideline based testing criteria (ie, prostate specific antigen 3-10, or <3 with suspicious digital rectal examination). RESULTS: Validation cohorts were prospectively enrolled from academic (977 patients, median prostate specific antigen 4.5, IQR 3.1-6.0) and community (548, median prostate specific antigen 4.9, IQR 3.7-6.8) settings. In the overall validation population (1,525 patients), 338 men (22%) had grade group ≥2 cancer on biopsy. The MyProstateScore threshold of 10 provided 97% sensitivity and 98% negative predictive value for grade group ≥2 cancer. MyProstateScore testing would have prevented 387 unnecessary biopsies (33%), while missing only 10 grade group ≥2 cancers (3.0%). In 1,242 patients meeting guideline based criteria, MyProstateScore ≤10 provided 96% sensitivity and 97% negative predictive value, and would have prevented 32% of unnecessary biopsies, missing 3.7% of grade group ≥2 cancers. CONCLUSIONS: In a large, clinically pertinent biopsy referral population, MyProstateScore ≤10 provided exceptional sensitivity and negative predictive value for ruling out grade group ≥2 cancer. This straightforward secondary testing approach would reduce the use of more costly and invasive procedures after screening with prostate specific antigen.

Corin plays a protective role via upregulating MAPK and downregulating eNOS in diabetic nephropathy endothelial dysfunction.

Diabetic nephropathy (DN) is one of the leading causes of mortality in diabetic patients, but its pathogenesis is unclear. We aimed to study the role of the pro-ANP convertase Corin in the pathogenesis of DN. Corin and ANP expression in DN rat kidneys and high-glucose-treated HK-2 cells was analyzed by real-time PCR, western blotting, and immunohistochemical staining. The effect of Corin-siRNA or ANP-siRNA HK-2 cells on EA.hy926 cell migration was determined by scratch-wound healing assay. The expression of mitogen-activated protein kinase (MAPK) and endothelial NO synthase (eNOS) in EA.hy926 cells treated with conditioned medium from Corin-siRNA- or ANP-siRNA-transfected HK-2 cells was determined by western blotting. We found a significant reduction in Corin and ANP expression in DN rat kidneys. These results were recapitulated in HK-2 cells treated with high glucose. EA.hy926 cells treated with conditioned medium from Corin-deficient HK-2 cells had inhibited migration, increased MAPK activity, and decreased eNOS activity. Similar effects were observed with ANP-siRNA transfection. Finally, adding ANP to the Corin-deficient HK-2 conditioned medium rescued the above defects, indicating that Corin mediates its effects through ANP. In conclusion, Corin plays a renoprotective role through pro-ANP processing, and defects in Corin cause endothelial dysfunction through MAPK and eNOS signaling in DN.

Dietary Na+ intake in healthy humans changes the urine extracellular vesicle prostasin abundance while the vesicle excretion rate, NCC, and ENaC are not altered.

Low Na+ intake activates aldosterone signaling, which increases renal Na+ reabsorption through increased apical activity of the NaCl cotransporter (NCC) and the epithelial Na+ channel (ENaC). Na+ transporter proteins are excreted in urine as an integral part of cell-derived extracellular vesicles (uEVs). It was hypothesized that Na+ transport protein levels in uEVs from healthy humans reflect their physiological regulation by aldosterone. Urine and plasma samples from 10 healthy men (median age: 22.8 yr) were collected after 5 days on a low-Na+ (70 mmol/day) diet and 5 days on a high-Na+ (250 mmol/day) diet. uEVs were isolated by ultracentrifugation and analyzed by Western blot analysis for EV markers (CD9, CD63, and ALIX), transport proteins (Na+-K+-ATPase α1-subunit, NCC, ENaC α- and γ-subunits, and aquaporin 2), and the ENaC-cleaving protease prostasin. Plasma renin and aldosterone concentrations increased during the low-Na+ diet. uEV size and concentration were not different between diets by tunable resistive pulse sensing. EV markers ALIX and CD9 increased with the low-Na+ diet, whereas CD63 and aquaporin 2 excretion were unchanged. Full-length ENaC γ-subunits were generally not detectable in uEVs, whereas ENaC α-subunits, NCC, and phosphorylated NCC were consistently detected but not changed by Na+ intake. Prostasin increased with low Na+ in uEVs. uEV excretion of transporters was not correlated with blood pressure, urinary Na+ and K+ excretion, plasma renin, or aldosterone. In conclusion, apical Na+ transporter proteins and proteases were excreted in uEVs, and while the excretion rate and size of uEVs were not affected, EV markers and prostasin increased in response to the low-Na+ diet.

Albuminuria is associated with an increased prostasin in urine while aldosterone has no direct effect on urine and kidney tissue abundance of prostasin.

The proteinase prostasin is a candidate mediator for aldosterone-driven proteolytic activation of the epithelial sodium channel (ENaC). It was hypothesized that the aldosterone-mineralocorticoid receptor (MR) pathway stimulates prostasin abundance in kidney and urine. Prostasin was measured in plasma and urine from type 2 diabetic patients with resistant hypertension (n = 112) randomized to spironolactone/placebo in a clinical trial. Prostasin protein level was assessed by immunoblotting in (1) human and rat urines with/without nephrotic syndrome, (2) human nephrectomy tissue, (3) urine and kidney from aldosterone synthase-deficient (AS-/-) mice and ANGII- and aldosterone-infused mice, and in (4) kidney from adrenalectomized rats. Serum aldosterone concentration related to prostasin concentration in urine but not in plasma. Plasma prostasin concentration increased significantly after spironolactone compared to control. Urinary prostasin and albumin related directly and were reduced by spironolactone. In patients with nephrotic syndrome, urinary prostasin protein was elevated compared to controls. In rat nephrosis, proteinuria coincided with increased urinary prostasin, unchanged kidney tissue prostasin, and decreased plasma prostasin while plasma aldosterone was suppressed. Prostasin protein abundance in human nephrectomy tissue was similar across gender and ANGII inhibition regimens. Prostasin urine abundance was not different in AS-/- and aldosterone-infused mice. Prostasin kidney level was not different from control in adrenalectomized rats and AS-/- mice. We found no evidence for a direct relationship between mineralocorticoid receptor signaling and kidney and urine prostasin abundance. The reduction of urinary prostasin in spironolactone-treated patients is most likely the result of an improved glomerular filtration barrier function and generally reduced proteinuria.

Racial Variation in the Utility of Urinary Biomarkers PCA3 and T2ERG in a Large Multicenter Study.

PURPOSE: To our knowledge it is unknown whether urinary biomarkers for prostate cancer have added utility to clinical risk calculators in different racial groups. We examined the utility of urinary biomarkers added to clinical risk calculators for predicting prostate cancer in African American and nonAfrican American men. MATERIALS AND METHODS: Demographics, PCPT (Prostate Cancer Prevention Trial) risk scores, data on the biomarkers data PCA3 (prostate cancer antigen 3) and T2ERG (transmembrane protease serine 2 and v-ets erythroblastosis virus E26 oncogene homolog gene fusion), and biopsy pathology features were prospectively collected on 718 men as part of EDRN (Early Detection Research Network). Utility was determined by generating ROC curves and comparing AUC values for the baseline multivariable PCPT model and for models containing biomarker scores. RESULTS: PCA3 and T2ERG added utility for the prediction of prostate cancer and clinically significant prostate cancer when combined with the PCPT Risk Calculator. This utility was seen in nonAfrican American men only for PCA3 (AUC 0.64 increased to 0.75 for prostate cancer and to 0.69-0.77 for clinically significant prostate cancer, both p <0.001) and for T2ERG (AUC 0.64-0.74 for prostate cancer, p <0.001, and 0.69-0.73 for clinically significant prostate cancer, p = 0.029). African American men did not have an added benefit with the addition of biomarkers, including PCA3 (AUC 0.75-0.77, p = 0.64, and 0.65-0.66, p = 0.74) and T2ERG (AUC 0.75-0.74, p = 0.74, and 0.65-0.64, p = 0.88), for prostate cancer and clinically significant prostate cancer, respectively. Limitations include the small number of African American men (72). The post hoc subgroup analysis nature of the study limited findings to being hypothesis generating. CONCLUSIONS: As novel biomarkers are discovered, clinical utility should be established across demographically diverse cohorts.

Prostate Cancer Detection and Prognosis: From Prostate Specific Antigen (PSA) to Exosomal Biomarkers.

Prostate specific antigen (PSA) remains the most used biomarker in the management of early prostate cancer (PCa), in spite of the problems related to false positive results and overdiagnosis. New biomarkers have been proposed in recent years with the aim of increasing specificity and distinguishing aggressive from non-aggressive PCa. The emerging role of the prostate health index and the 4Kscore is reviewed in this article. Both are blood-based tests related to the aggressiveness of the tumor, which provide the risk of suffering PCa and avoiding negative biopsies. Furthermore, the use of urine has emerged as a non-invasive way to identify new biomarkers in recent years, including the PCA3 and TMPRSS2:ERG fusion gene. Available results about the PCA3 score showed its usefulness to decide the repetition of biopsy in patients with a previous negative result, although its relationship with the aggressiveness of the tumor is controversial. More recently, aberrant microRNA expression in PCa has been reported by different authors. Preliminary results suggest the utility of circulating and urinary microRNAs in the detection and prognosis of PCa. Although several of these new biomarkers have been recommended by different guidelines, large prospective and comparative studies are necessary to establish their value in PCa detection and prognosis.

Diabetic nephropathy is associated with increased urine excretion of proteases plasmin, prostasin and urokinase and activation of amiloride-sensitive current in collecting duct cells.

BACKGROUND: Diabetic nephropathy (DN) is associated with hypertension, expanded extracellular volume and impaired renal Na(+) excretion. It was hypothesized that aberrant glomerular filtration of serine proteases in DN causes proteolytic activation of the epithelial sodium channel (ENaC) in the kidney by excision of an inhibitory peptide tract from the γ subunit. METHODS: In a cross-sectional design, urine, plasma and clinical data were collected from type 1 diabetic patients with DN (n = 19) and matched normoalbuminuric type 1 diabetics (controls, n = 20). Urine was examined for proteases by western immunoblotting, patch clamp and ELISA. Urine exosomes were isolated to elucidate potential cleavage of γENaC by a monoclonal antibody directed against the 'inhibitory' peptide tract. RESULTS: Compared with control, DN patients displayed significantly higher blood pressure and urinary excretion of plasmin(ogen), prostasin and urokinase that correlated directly with urine albumin. Western blotting confirmed plasmin, prostasin and urokinase in urine from the DN group predominantly. Urine from DN evoked a significantly larger amiloride-sensitive inward current in single collecting duct cells compared with controls. Immunoblotting of urine exosomes showed aquaporin 2 in all patient samples. Exosomes displayed a virtual absence of intact γENaC while moieties compatible with cleavage by furin only, were shown in both groups. Proteolytic cleavage by the extracellular serine proteases plasmin or prostasin was observed in DN samples predominantly. CONCLUSION: DN is associated with increased urinary excretion of plasmin, prostasin and urokinase and proteolytic activation of ENaC that might contribute to impaired renal Na(+) excretion and hypertension.

Hormone-dependent changes in female urinary proteome.

Human urine represents a good source for proteomic research for clinically related studies as it can be collected and processed easily and can give information about kidney-related mechanisms. Little is known about the urinary proteomic changes resulting from physiological (normal), pathological, or environmental variations, and there are few reports on hormone-related modifications of urine proteome. In our study, we highlighted the variations of urinary proteins associated with menstrual cycle or estro-progestin pill in females. We also described an association between some urinary proteins and the renin-angiotensin-aldosterone system, which might help to improve the understanding of physiological and pathological processes when a gender-specific pattern such as the menopause-related hypertension or eclampsia is evident. We therefore support the usefulness of urinary proteomics as a valuable tool for clinically related study as it can provide information on candidate biomarkers which, in turn, need to be confirmed by multiple approaches before the use in a clinical setting.

Comparative evaluation of urinary PCA3 and TMPRSS2: ERG scores and serum PHI in predicting prostate cancer aggressiveness.

It has been suggested that urinary PCA3 and TMPRSS2:ERG fusion tests and serum PHI correlate to cancer aggressiveness-related pathological criteria at prostatectomy. To evaluate and compare their ability in predicting prostate cancer aggressiveness, PHI and urinary PCA3 and TMPRSS2:ERG (T2) scores were assessed in 154 patients who underwent radical prostatectomy for biopsy-proven prostate cancer. Univariate and multivariate analyses using logistic regression and decision curve analyses were performed. All three markers were predictors of a tumor volume≥0.5 mL. Only PHI predicted Gleason score≥7. T2 score and PHI were both independent predictors of extracapsular extension(≥pT3), while multifocality was only predicted by PCA3 score. Moreover, when compared to a base model (age, digital rectal examination, serum PSA, and Gleason sum at biopsy), the addition of both PCA3 score and PHI to the base model induced a significant increase (+12%) when predicting tumor volume>0.5 mL. PHI and urinary PCA3 and T2 scores can be considered as complementary predictors of cancer aggressiveness at prostatectomy.

[New challenges and earlier approved methods in the laboratory diagnosis of prostate cancer]. / Új lehetoségek és bevált utak a prosztatarák laboratóriumi diagnosztikájában.

Prostate cancer is usually a disease of elderly men, however, over 40 years of age the tumor can appear at any times. PSA is a protein molecule synthesized by prostate cells. Measurement of serum PSA has revolutionized the diagnosis and treatment of prostate cancer. However, PSA is not sufficiently specific for the detection of prostate cancer, since serum PSA might also be elevated in benign prostate diseases, as well as following physical stimulation of the gland (digital rectal examination, biopsy, catheterization, or even ejaculation). To increase the specificity of PSA, different derivative parameters have been developed i.e. PSA density (ratio of PSA to prostate volume), PSA velocity (change of PSA over a time period) or age-specific reference ranges. 65-95% of circulating PSA is bound to different proteins, while the rest of PSA circulates in a non-bound form (free PSA, fPSA). In addition to fPSA, the prostate health index [phi; (-2)proPSA/fPSA×√PSA] is increasingly used to differentiate between carcinoma-induced and non-carcinoma-induced increase in PSA. PCA3 is a non-coding messenger RNA, which is 60-70-fold overexpressed by cancer cells in the prostate. Measurement of urine PCA3 appears to be more sensitive than %tPSA, and is independent of prostate volume, age or tPSA. The author reviews laboratory biomarkers related to prostate cancer, used either in the routine clinical practice, or in research. Laboratory biomarkers seem to be useful tools to reduce the incidence of advanced stage, or metastatic prostate cancer, and the cancer-related death rate. A promising perspective for the future is the detection of circulating prostate cancer cells and the profiling of microRNAs, especially on the field of tumor prognosis.

HtrA1 in human urothelial bladder cancer: a secreted protein and a potential novel biomarker.

Our aim was to analyze the expression of the serine protease HtrA1 in human bladder tissue and urine in order to point out its possible association with the presence of urothelial bladder cancer. Bladder tissue and urine specimens from cancer patients with different tumor grades and stages (n = 68) and from individuals with cystitis (n = 16) were collected along with biopsy specimens and urine from healthy individuals (n = 68). For the first time, we demonstrated by immunohistochemistry that HtrA1 protein is produced by bladder urothelium in both physiological and inflammatory conditions, whereas it is not detectable in urothelial cancer cells regardless of tumor grade and stage. A different HtrA1 expression between normal-looking and neoplastic bladder tissue, despite similar HtrA1 mRNA levels, was also found by western blotting, which disclosed the presence of two forms of HtrA1, a native form of ∼50 kDa and an autocatalytic form of ∼38 kDa. Our investigations documented the presence of the two forms of HtrA1 also in urine. The ∼38 kDa form was significantly down-regulated in neoplastic tissue, whereas significantly higher amounts of both HtrA1 forms were found in urine from cancer patients compared with both healthy subjects and patients with cystitis. Our findings suggest that HtrA1 is a downexpressed molecule since an early stage of bladder urothelial carcinoma development and that urinary HtrA1 protein may be considered, if successfully validated, as an early and highly sensitive and specific biomarker for this neoplasia (the sensitivity and specificity of HtrA1 are 92.65% and 95.59%, respectively).

Urine TMPRSS2:ERG fusion transcript integrated with PCA3 score, genotyping, and biological features are correlated to the results of prostatic biopsies in men at risk of prostate cancer.

BACKGROUND: Detection of fusion gene TMPRSS2:ERG transcripts in urine have been recently described in order to refine urine-based detection of prostate cancer (PCa), but data its clinical impact remain scarce. We aimed at investigating the correlation of TMPRSS2:ERG, prostate cancer antigen 3 (PCA3), prostate specific antigen (PSA) density, genetic variants, and androgenic status with outcome and pathological findings at prostatic biopsy. METHODS: Between 2007 and 2011, 291 patients at risk of PCa because of PSA > 3.0 ng/ml (55%) or candidate to active surveillance protocol justifying restaging biopsy management (45%) were recruited. TMPRSS2:ERG was detected by urine assay (Progensa™). PCA3-score, PSA level, bioavailable testosterone level, prostate volume, rs1447295 and rs6983267 genotypes were prospectively assessed. Univariate and multivariate analysis by logistic regression model (logit) were conducted to study the correlation of TMPRSS2:ERG status, PCA3, and PSA density with biopsy results, and Gleason score. RESULTS: Of 291 patients, 173 had PCa and 118 had negative biopsy. PCA3 score, PSA density and TMPRSS2:ERG-score were correlated with presence of PCa (P < 0.0001, P = 0.046, and P < 0.0001, respectively). This correlation remained strong on multivariable analysis model (area under curve 0.743). PCA3 score and PSA density were significantly associated with presence of Grade 4 through multivariable analysis. PCA3 score was also correlated to the percentage of positive cores at biopsy (P = 0.008). CONCLUSIONS: Integration of levels TMPRSS2:ERG transcripts in urine, with PCA3-score, androgenic status, genetic status and traditional clinical variables could significantly increase detection of high risk localized PCa.

Reduced urinary corin levels in patients with chronic kidney disease.

Corin is a cardiac protease that regulates BP (blood pressure) by activating natriuretic peptides. Recent animal studies identified corin expression in the kidney where it may regulate renal function. In the present study, we tested the hypothesis that corin may be present in human urine and that urinary corin levels may be altered in patients with kidney disease. We obtained urine and kidney tissue samples from normal individuals and CKD (chronic kidney disease) patients. Using ELISA, we detected corin protein in human urine. In normal individuals, urinary corin levels did not correlate with that of plasma, indicating that urinary corin is probably of kidney origin. Compared with normal controls, CKD patients had markedly reduced urinary corin levels and this reduction correlated with disease severity. By immunostaining, human corin protein was identified on the epithelial cell surface in renal tubules. The renal corin mRNA and protein levels were significantly lower in CKD patients than non-CKD controls. The results indicate that renal tubular corin may be shed into urine and that urinary and renal corin levels were reduced in CKD patients. These data suggest that reduced corin levels in the kidney may reflect the underlying pathology in CKD.

Urinary prostasin excretion is associated with adiposity in nonhypertensive African-American adolescents.

BACKGROUND: Metabolic abnormalities in obesity can overstimulate the renal epithelial sodium channel (ENaC) and subsequently lead to blood pressure (BP) elevation. Prostasin, a membrane-bound/secretive serine protease, is thought to activate ENaC via the proteolytic cleavage of the channel. Our specific aim was to explore whether there is a relationship between adiposity and urinary prostasin excretion at the population level. METHODS: In 271 African-American adolescents, urinary prostasin concentrations were determined by enzyme-linked immunosorbent assay and normalized by urinary creatinine. RESULTS: Urinary prostasin excretion increased in the overweight/obese group (n = 110, 38.2 ± 4.0 ng/mg) vs. the normal-weight group (n = 161, 20.7 ± 1.2 ng/mg, P = 0.03). Urinary prostasin excretion was significantly correlated with BMI percentiles (r = 0.14, P = 0.02), waist circumference (r = 0.13, P = 0.05), total body fat mass (r = 0.20, P < 0.01), and percentage body fat (r = 0.23, P < 0.01). Urinary prostasin excretion was also correlated with plasma aldosterone (r = 0.11, P = 0.05) and systolic BP (SBP; r = 0.15, P = 0.02), but the significances disappeared after adjustment of any of the adiposity variables. CONCLUSION: Our data for the first time suggest that adiposity plays a role in urinary prostasin excretion, and its associations with aldosterone and BP appear to be modulated by adiposity. Whether urinary prostasin excretion is a biomarker/mechanism underlying obesity-related hypertension deserves further investigations.

Urinary prostasin: a possible biomarker for renal pressure natriuresis in black adolescents.

Prostasin is a membrane-bound/secretive serine protease interacting with aldosterone and the epithelial sodium channel in the kidney. We and others have previously proposed the concept of stress-induced pressure natriuresis (SIPN) where increased urinary sodium excretion (UNaV) is coupled with elevated blood pressure (BP) in response to behavioral stress in normotensive adolescents. This study thus aimed to test the relationship between prostasin and pressure natriuresis using the SIPN model. A cohort of 102 normotensive black adolescents (mean age: 17.0 +/- 1.2 y; 56% females) were placed on a controlled sodium (4000 +/- 200 mg/d) and potassium (2600 +/- 200 mg/d) diet for three days before testing. The SIPN protocol consisted of a 1-h baseline period, a 1-h stress period (competitive video game), and a 1-h recovery period. During the stress period, BP elevation was coupled with an increase in UNaV. Urinary prostasin concentration had more than a 2-fold reduction from baseline (38.4 +/- 32.7 ng/mL) to stress (17.2 +/- 16.0 ng/mL), and further declined during recovery (12.1 +/- 16.2 ng/mL) (p < 0.001). Urinary prostasin was inversely correlated with UNaV during stress (r = -0.43, p = 0.0001), even after being normalized by urinary creatinine. Our data suggest that urinary prostasin could be a novel biomarker and/or mechanism for renal pressure natriuresis in normotensive black adolescents.

Incorporation of Urinary Prostate Cancer Antigen 3 and TMPRSS2:ERG into Prostate Cancer Prevention Trial Risk Calculator.

BACKGROUND: The Prostate Cancer Prevention Trial Risk Calculator (PCPTRC) is a commonly used risk tool for predicting the outcome on biopsy based on the established risk factors. OBJECTIVE: To determine whether incorporation of the novel urinary markers prostate cancer antigen 3 (PCA3) and TMPRSS2:ERG (T2:ERG) into the PCPTRC improves its discrimination, accuracy, and clinical net benefit. DESIGN, SETTING, AND PARTICIPANTS: Since PCA3 and T2:ERG were not measured as part of the PCPTRC, a Bayesian modeling approach was used to combine data where the markers were measured in a Michigan cohort with the PCPTRC as prior probabilities to form an updated PCPTRC. This update was compared to the existing PCPTRC on an independent Early Detection Research Network cohort in terms of discrimination, calibration, and decision curve analysis. RESULTS AND LIMITATIONS: Among the 1225 Michigan biopsies, 57.7%, 24.0%, and 18.3% were negative, with low- and high-grade (Gleason grade≥7) prostate cancer, respectively. Evaluated on the Early Detection Research Network validation set comprising 854 biopsies, areas under the curve (95% confidence interval) for predicting high-grade cancer in the 854 biopsies comprising the validation set were 70.0% (66.0-74.0%), 76.4% (72.8-80.0%), and 77.1% (73.6-80.6%) for the PCPTRC alone, with PCA3 added, and PCA3 and T2:ERG added, respectively. Net benefit was improved for the updated PCPTRC, while calibration was not. Limitations are that the updated PCPTRC is based on two different cohorts, the PCPT and Michigan, and that 20% of the validation set came from the Michigan center. More validation is required; hence, the updated risk tool is posted online. CONCLUSIONS: Incorporation of PCA3 into the PCPTRC improved validation on an independent cohort, whereas T2:ERG offered negligible utility in addition to PCA3. PATIENT SUMMARY: After passing external validation, prostate cancer antigen 3 has been added to the online Prostate Cancer Prevention Trial Risk Calculator for use by patients in deciding whether to proceed to biopsy. TMPRSS2:ERG did not improve prediction on the external validation set, but is included for further validation.

Activity-based Protein Profiling Approaches for Transplantation.

Enzyme activity may be more pathophysiologically relevant than enzyme quantity and is regulated by changes in conformational status that are undetectable by traditional proteomic approaches. Further, enzyme activity may provide insights into rapid physiological responses to inflammation/injury that are not dependent on de novo protein transcription. Activity-based protein profiling (ABPP) is a chemical proteomic approach designed to characterize and identify active enzymes within complex biological samples. Activity probes have been developed to interrogate multiple enzyme families with broad applicability, including but not limited to serine hydrolases, cysteine proteases, matrix metalloproteases, nitrilases, caspases, and histone deacetylases. The goal of this overview is to describe the overall rationale, approach, methods, challenges, and potential applications of ABPP to transplantation research. To do so, we present a case example of urine serine hydrolase ABPP in kidney transplant rejection to illustrate the utility and workflow of this analytical approach. Ultimately, developing novel transplant therapeutics is critically dependent on understanding the pathophysiological processes that result in loss of transplant function. ABPP offers a new dimension for characterizing dynamic changes in clinical samples. The capacity to identify and measure relevant enzyme activities provides fresh opportunities for understanding these processes and may help identify markers of disease activity for the development of novel diagnostics and real-time monitoring of patients. Finally, these insights into enzyme activity may also help to identify new transplant therapeutics, such as enzyme-specific inhibitors.

Performance of PCA3 and TMPRSS2:ERG urinary biomarkers in prediction of biopsy outcome in the Canary Prostate Active Surveillance Study (PASS).

BACKGROUND: For men on active surveillance for prostate cancer, biomarkers may improve prediction of reclassification to higher grade or volume cancer. This study examined the association of urinary PCA3 and TMPRSS2:ERG (T2:ERG) with biopsy-based reclassification. METHODS: Urine was collected at baseline, 6, 12, and 24 months in the multi-institutional Canary Prostate Active Surveillance Study (PASS), and PCA3 and T2:ERG levels were quantitated. Reclassification was an increase in Gleason score or ratio of biopsy cores with cancer to ≥34%. The association of biomarker scores, adjusted for common clinical variables, with short- and long-term reclassification was evaluated. Discriminatory capacity of models with clinical variables alone or with biomarkers was assessed using receiver operating characteristic (ROC) curves and decision curve analysis (DCA). RESULTS: Seven hundred and eighty-two men contributed 2069 urine specimens. After adjusting for PSA, prostate size, and ratio of biopsy cores with cancer, PCA3 but not T2:ERG was associated with short-term reclassification at the first surveillance biopsy (OR = 1.3; 95% CI 1.0-1.7, p = 0.02). The addition of PCA3 to a model with clinical variables improved area under the curve from 0.743 to 0.753 and increased net benefit minimally. After adjusting for clinical variables, neither marker nor marker kinetics was associated with time to reclassification in subsequent biopsies. CONCLUSIONS: PCA3 but not T2:ERG was associated with cancer reclassification in the first surveillance biopsy but has negligible improvement over clinical variables alone in ROC or DCA analyses. Neither marker was associated with reclassification in subsequent biopsies.

Regulation of prostasin by aldosterone in the kidney.

Prostasin is a serine protease present in mammalian urine that increases the activity of the epithelial sodium channel (ENaC) when the two are coexpressed in Xenopus oocytes. To determine if aldosterone, one of the principal regulators of urinary Na reabsorption by the distal nephron, affects prostasin expression, we examined prostasin mRNA and protein in a cultured mouse cortical collecting duct cell line (M-1), whole rats, and patients with primary aldosteronism. Aldosterone treatment of M-1 cells substantially increased prostasin expression and stimulated (22)Na uptake. Urinary excretion of prostasin in rats that were infused with aldosterone likewise increased by approximately 4-fold when compared with the vehicle-infused rats. Finally, urinary excretion of prostasin in patients with primary aldosteronism was substantially increased when compared with normal patients. Adrenalectomy reduced urinary prostasin excretion to control levels, whereas urinary prostasin levels were not altered in patients undergoing surgery for other reasons. In patients with primary aldosteronism, reduction in the urinary excretion of prostasin correlated with the increase in the urinary Na/K ratio. These findings, together with our previous report that prostasin activates the amiloride-sensitive Na currents through ENaC, demonstrate that prostasin regulates Na balance in vivo by virtue of its heightened expression in the presence of aldosterone.

Increased urinary excretion of the epithelial Na channel activator prostasin in patients with primary aldosteronism.

OBJECTIVES: Prostasin is a glycosylphosphatidylinositol-anchored serine protease that is released in urine and is involved in epithelial Na channel activation. A direct association between urinary prostasin (u-prostasin) concentration and activation of the aldosterone-driven pathway has been suggested; however, in previous studies on primary aldosteronism, a semiquantitative evaluation, rather than a precise quantification, of prostasin was performed. We aim to investigate if u-prostasin concentrations are higher in patients with primary aldosteronism than in patients with essential hypertension and whether u-prostasin measurements could be a useful marker for diagnosing primary aldosteronism in hypertensive patients. METHODS: A total of 62 primary aldosteronism and 56 essential hypertension patients were enrolled. Biochemical and hormonal parameters were measured by applying routine laboratory methods, and u-prostasin levels were assessed by ELISA. RESULTS: Primary aldosteronism patients had higher u-prostasin levels than did essential hypertension patients. Prostasin levels were positively correlated with the aldosterone-to-renin ratio and inversely correlated with plasma K and urinary Na levels. In the highest concentration quartile, u-prostasin levels were associated with a several-fold higher probability of primary aldosteronism diagnosis in hypertensive patients. Receiver operating characteristic curve analysis showed that prostasin was specific but poorly sensitive as a diagnostic marker for primary aldosteronism. CONCLUSIONS: The study shows that an elevated u-prostasin concentration in humans is a specific marker for primary aldosteronism, which involves the classical model of epithelial Na channel activation. There was no statistically significant difference in prostasin concentrations among patients with different primary aldosteronism subtypes. Studies with a larger series of patients are necessary to clarify the clinical usefulness of the prostasin assay.