The kinetic parameters, steroid substrate specificity and identities of reaction products were determined for four homogeneous recombinant human 3alpha-hydroxysteroid dehydrogenase (3alpha-HSD) isoforms of the aldo-keto reductase (AKR) superfamily. The enzymes correspond to type 1 3alpha-HSD (AKR1C4), type 2 3alpha(17beta)-HSD (AKR1C3), type 3 3alpha-HSD (AKR1C2) and 20alpha(3alpha)-HSD (AKR1C1), and share at least 84% amino acid sequence identity. All enzymes acted as NAD(P)(H)-dependent 3-, 17- and 20-ketosteroid reductases and as 3alpha-, 17beta- and 20alpha-hydroxysteroid oxidases. The functional plasticity of these isoforms highlights their ability to modulate the levels of active androgens, oestrogens and progestins. Salient features were that AKR1C4 was the most catalytically efficient, with k(cat)/K(m) values for substrates that exceeded those obtained with other isoforms by 10-30-fold. In the reduction direction, all isoforms inactivated 5alpha-dihydrotestosterone (17beta-hydroxy-5alpha-androstan-3-one; 5alpha-DHT) to yield 5alpha-androstane-3alpha,17beta-diol (3alpha-androstanediol). However, only AKR1C3 reduced Delta(4)-androstene-3,17-dione to produce significant amounts of testosterone. All isoforms reduced oestrone to 17beta-oestradiol, and progesterone to 20alpha-hydroxy-pregn-4-ene-3,20-dione (20alpha-hydroxyprogesterone). In the oxidation direction, only AKR1C2 converted 3alpha-androstanediol to the active hormone 5alpha-DHT. AKR1C3 and AKR1C4 oxidized testosterone to Delta(4)-androstene-3,17-dione. All isoforms oxidized 17beta-oestradiol to oestrone, and 20alpha-hydroxyprogesterone to progesterone. Discrete tissue distribution of these AKR1C enzymes was observed using isoform-specific reverse transcriptase-PCR. AKR1C4 was virtually liver-specific and its high k(cat)/K(m) allows this enzyme to form 5alpha/5beta-tetrahydrosteroids robustly. AKR1C3 was most prominent in the prostate and mammary glands. The ability of AKR1C3 to interconvert testosterone with Delta(4)-androstene-3,17-dione, but to inactivate 5alpha-DHT, is consistent with this enzyme eliminating active androgens from the prostate. In the mammary gland, AKR1C3 will convert Delta(4)-androstene-3,17-dione to testosterone (a substrate aromatizable to 17beta-oestradiol), oestrone to 17beta-oestradiol, and progesterone to 20alpha-hydroxyprogesterone, and this concerted reductive activity may yield a pro-oesterogenic state. AKR1C3 is also the dominant form in the uterus and is responsible for the synthesis of 3alpha-androstanediol which has been implicated as a parturition hormone. The major isoforms in the brain, capable of synthesizing anxiolytic steroids, are AKR1C1 and AKR1C2. These studies are in stark contrast with those in rat where only a single AKR with positional- and stereo-specificity for 3alpha-hydroxysteroids exists.

The kinetic parameters, steroid substrate specificity and identities of reaction products were determined for four homogeneous recombinant human 3α-hydroxysteroid dehydrogenase (3α-HSD) isoforms of the aldo-keto reductase (AKR) superfamily. The enzymes correspond to type 1 3α-HSD (AKR1C4), type 2 3α(17β)-HSD (AKR1C3), type 3 3α-HSD (AKR1C2) and 20α(3α)-HSD (AKR1C1), and share at least 84 % amino acid sequence identity. All enzymes acted as NAD(P)(H)-dependent 3-, 17-and 20-ketosteroid reductases and as 3α-, 17β-and 20α-hydroxysteroid oxidases. The functional plasticity of these isoforms highlights their ability to modulate the levels of active androgens, oestrogens and progestins. Salient features were that AKR1C4 was the most catalytically efficient, with k cat \K m values for substrates that exceeded those obtained with other isoforms by 10-30-fold. In the reduction direction, all isoforms inactivated 5α-dihydrotestosterone (17β-hydroxy-5α-androstan-3-one ; 5α-DHT) to yield 5α-androstane-3α,17β-diol (3α-androstanediol). However, only AKR1C3 reduced ∆%-androstene-3,17-dione to produce significant amounts of testosterone. All isoforms reduced oestrone to 17β-oestradiol, and progesterone to 20α-hydroxypregn-4-ene-3,20-dione (20α-hydroxyprogesterone). In the oxidation direction, only AKR1C2 converted 3α-androstanediol to the active hormone 5α-DHT. AKR1C3 and AKR1C4 oxidized testosterone to ∆%-androstene-3,17-dione. All isoforms oxid-

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We assessed the efficacy of interferon (IFN) alpha-2b plus ribavirin therapy in patients with hepatitis C virus (HCV)-related cirrhosis, and elucidated the risk factors for the development of hepatocellular carcinoma (HCC) to determine whether these therapies might reduce the incidence of HCC. One hundred and thirty-two HCV-cirrhotic patients receiving IFN alpha-2b (3 or 5 MU thrice weekly) and oral ribavirin (1,000-1,200 mg/day) for 24 or 48 weeks were analysed. Cumulative incidence of HCC was estimated by the Kaplan-Meier method. The prognostic relevance of clinical variables and HCC occurrence was evaluated by univariate analysis with the log-rank test and by multivariate Cox's regression analysis. A total of 116 patients completed the treatment and 73 (55%) achieved a sustained virological response (SVR). Stepwise logistic regression analysis showed that nongenotype 1b (P < 0.001) and low viral load (P = 0.018) were independent variables of SVR. During a median follow-up period of 37 (12-63) months, HCC developed in 11 patients with non-SVR and five with SVR (P = 0.0178), whereas there was no difference between those with transient biochemical response and nonresponse (P = 0.5970). The Kaplan-Meier method also showed that old age (>or=60 years) (P = 0.0034) and genotype 1b (P = 0.0104) were associated with HCC occurrence. Using Cox's regression analysis, non-SVR (odds ratio = 3.521, P = 0.036), male (odds ratio = 6.269, P = 0.011) and old age (odds ratio = 3.076, P = 0.049) were independent significant risk factors contributing to HCC development. Our results suggest that achieving SVR by IFN alpha-2b plus ribavirin therapy may decrease the incidence of HCC in patients with HCV-related cirrhosis.

BackgroundUntil now, no risk score could predict hepatocellular carcinoma (HCC) in nucleos(t)ide analog (NA)-treated Asian patients.MethodsWe enrolled 1325 NA-naïve chronic hepatitis B patients with entecavir monotherapy for >12 months, with 883 and 442 patients randomly assigned to the development and validation groups, respectively, in the risk model.ResultsThe cumulative probabilities of HCC were 2.4%, 4.1%, and 9.9% after 2, 3, and 5 years of treatment, respectively. In the development group, age, platelet counts, and alpha-fetoprotein levels after 12 months of treatment were the independent predictors of HCC. We converted the Cox proportional hazards regression coefficients for these predictors into risk scores and developed the APA-B model, with the total risk scores ranging from 0 to 15. The risk scores accurately categorized patients with low (0–5), medium (6–9), and high (10–15) risks in the validation group (P <0.001). The areas under the receiver operating characteristic curve for predicting HCC risk after 2, 3, and 5 years were 0.877, 0.842, and 0.827, respectively, in the development group and 0.939, 0.892, and 0.862, respectively, in the validation group.ConclusionThe proposed HCC risk prediction model exhibited excellent predictive accuracy in NA-naïve Asian patients receiving entecavir therapy.

This study aims to assess the nephrotoxicity and efficacy of tenofovir disoproxil fumarate (tenofovir), telbivudine and entecavir. A retrospective study of 587 patients with chronic hepatitis B treated with tenofovir (n = 170), telbivudine (n = 184) and entecavir (n = 233) for at least 1 year. Renal function and efficacy were assessed. The estimated glomerular filtration rate (eGFR) decreased significantly in the tenofovir group after a mean of 17 months treatment (from 92.2 to 85.6 mL/min/1.73 m(2), p < 0.001), but increased in the telbivudine group after a mean of 32 months of treatment (from 86.1 to 95 mL/min/1.73 m(2), p < 0.001). There was no significant change in eGFR in the entecavir group after a mean of 44 months. By multivariate analysis, pre-existing renal insufficiency (p = 0.003), tenofovir (p = 0.007) and diuretic treatment (p = 0.001) were independent predictors for renal function deterioration. Cumulative virological breakthrough was 0% in tenofovir after 2 years, 3.4% in entecavir after 7 years and 22.9% in telbivudine after 5 years. Liver cirrhosis (p = 0.008) and virological breakthrough (p = 0.040) were independently associated with increased risk of hepatocellular carcinoma development. Tenofovir may lead to deterioration in renal function as assessed by serial eGFR measurements. Although telbivudine appeared to be associated with an improvement in eGFR, it was associated with high rates of virological breakthrough, which was an independent risk factor for HCC development. With low rates of virological breakthrough and preservation of renal function, entecavir could be the best choice among these three agents.

With the novel risk scores, we can estimate the chance of HCC development more exactly and practically. This approach can be used for HCC screening in CHC patients achieving SVR.

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