Myat Oo Aung

Role of the miR‐106b‐25 microRNA cluster in hepatocellular carcinoma

MicroRNAs are tiny RNA molecules which serve as important post‐transcriptional regulators of gene expression. Dysregulated expression of microRNAs has been observed in human cancers, indicating that microRNAs may function as oncogenes or as tumor suppressors. To date, the microRNAs encoded by the oncogenic miR‐17‐92 cluster, and its paralog the miR‐106b‐25 cluster, are among those which are differentially expressed in human cancers. In this study, we examined and confirmed the over‐expression of these clusters in hepatocellular carcinoma and in hepatoma‐derived cells. At least 50% of the tumor samples showed a greater than two‐fold increase in the expression for miR‐18 and for the miR‐106b‐25 cluster when compared with the corresponding paired non‐tumor samples. Knock‐down studies for the miR‐106b‐25 cluster, which includes miR‐106b, miR‐93 and miR‐25, showed that the expression of the cluster is necessary for cell proliferation and for anchorage‐independent growth. In tumors with high expression of this cluster, reduced expression of the BH3‐only protein Bim, a miR‐25 target, was observed. We further identified the transcription factor E2F1 as a target gene for miR‐106b and miR‐93 and it is likely that one of the roles of the miR‐106b‐25 cluster is to prevent excessively high E2F1 expression, which may then cause apoptosis. We conclude that there is aberrant expression of microRNAs encoded by the oncogenic miR‐17‐92 cluster and the miR‐106b‐25 cluster in hepatocellular carcinoma. The consistent overexpression of the miR‐106b‐25 cluster and its role in cell proliferation and anchorage‐independent growth points to the oncogenic potential of this cluster. (Cancer Sci 2009; 100: 1234–1242)

Fibroblast growth factor receptor 4 regulates proliferation, anti-apoptosis and alpha-fetoprotein secretion during hepatocellular carcinoma progression and represents a potential target for therapeutic intervention

BACKGROUND/AIMS FGFR4, a member of the fibroblast growth factor receptor family, has been recently associated with progression of melanoma, breast and head and neck carcinoma. Given its uniquely high expression in the liver, we investigated its contributory role to hepatocellular carcinoma (HCC). METHODS We performed a comprehensive sequencing of full-length FGFR4 transcript in 57 tumor/normal HCC tissue pairs, and quantified their mRNA expressions. Notable mutations and expression patterns were correlated with patient data. Clinically significant trends were examined in in vitro models. RESULTS We found eight genetic alterations including two highly frequent polymorphisms (V10I and G338R). Secretion of alpha-fetoprotein (AFP), a HCC biomarker, was increased among patients bearing homozygous Arg388 alleles. One-third of these patients exhibited increased FGFR4 mRNA expression in the matched tumor/normal tissue. Subsequent in vitro perturbation of FGFR4 signaling through both FGF19-stimulation and FGFR4 silencing confirmed a mechanistic link between FGFR4 activities and tumor aggressiveness. More importantly, inhibition of FGFR activity with PD173074 exquisitely blocked HuH7 (high FGFR4 expression) proliferation as compared to control cell lines. CONCLUSIONS FGFR4 contributes significantly to HCC progression by modulating AFP secretion, proliferation and anti-apoptosis. Its frequent overexpression in patients renders its inhibition a novel and much needed pharmacological approach against HCC.

Utility of the Health Belief Model in predicting compliance of screening in patients with chronic hepatitis B

Background : Regular surveillance is recommended for patients with chronic hepatitis B, to select candidates for anti‐viral therapy and detect early complications. However, factors that determine compliance are not well studied.

Klotho-beta overexpression as a novel target for suppressing proliferation and fibroblast growth factor receptor-4 signaling in hepatocellular carcinoma

BackgroundWe had previously demonstrated overexpression of fibroblast growth factor receptor-4 (FGFR4) in hepatocellular carcinoma (HCC). However, additional molecular mechanisms resulting in amplified FGFR4 signaling in HCC remain under-studied. Here, we studied the mechanistic role of its co-receptor klotho-beta (KLB) in driving elevated FGFR4 activity in HCC progression.ResultsQuantitative real-time PCR analysis identified frequent elevation of KLB gene expression in HCC tumors relative to matched non-tumor tissue, with a more than two-fold increase correlating with development of multiple tumors in patients. KLB-silencing in Huh7 cells decreased cell proliferation and suppressed FGFR4 downstream signaling. While transient repression of KLB-FGFR4 signaling decreased protein expression of alpha-fetoprotein (AFP), a HCC diagnostic marker, prolonged inhibition enriched for resistant HCC cells exhibiting increased liver stemness.ConclusionsElevated KLB expression in HCC tissues provides further credence to the oncogenic role of increased FGFR4 signaling in HCC progression and represents a novel biomarker to identify additional patients amenable to anti-FGFR4 therapy. The restricted tissue expression profile of KLB, together with the anti-proliferative effect observed with KLB-silencing, also qualifies it as a specific and potent therapeutic target for HCC patients. The enrichment of a liver stem cell-like population in response to extended KLB-FGFR4 repression necessitates further investigation to target the development of drug resistance.

Resolution of adefovir‐related nephrotoxicity by adefovir dose‐reduction in patients with chronic hepatitis B

Chronic hepatitis B patients (CHB) treated with adefovir were followed up to evaluate nephrotoxicity and its outcome.

Clinical outcomes of lamivudine-adefovir therapy in chronic hepatitis B cirrhosis.

Goals To determine the clinical outcome of chronic hepatitis B cirrhotics on antiviral therapy. Background The long-term outcome of hepatitis B cirrhotics on therapy remains to be characterized. Methods A large clinic cohort of chronic hepatitis B cirrhotic patients were enrolled in a treatment program of lamivudine±adefovir therapy. Patients were analyzed for clinical outcomes, and predictors of these outcomes were evaluated by multivariate analysis. Clinical outcomes of ascites, encephalopathy, hepatocellular carcinoma (HCC), and progression in Child-Pugh score, Model for End-stage Liver Disease score, and mortality were assessed. Data were analyzed by Kaplan-Meier graphs, log-rank test, and Cox regression. Results Of 143 chronic hepatitis B cirrhotics, 19.6% had decompensated cirrhosis. At 5 years, the mean survival was 83.6%, development of ascites, HCC, encephalopathy, and deterioration in Child-Pugh score were 7.0%, 15.9%, 10.8%, and 16.9%, respectively. The overall progression of liver-related complications was 32.8% at 5 years. Multivariate analysis showed that ascites, albumin ⩽28 g/L, Child-Pugh score ≥7.9, Model for End-stage Liver Disease score ≥10.9 were significantly associated with liver-related complications. Low albumin and low hepatitis B virus DNA were independent factors for liver-associated mortality. Lamivudine resistance did not affect mortality or liver disease progression. When stratified by Child-Pugh status, the mean survival of those with Child C cirrhosis was worse than Child A and B cirrhosis (P<0.001, log-rank test). Early deaths (⩽12 mo) were due to liver failure or sepsis, whereas deaths ≥12 mo were mainly due to HCC. Conclusion Decompensated chronic hepatitis B cirrhotics may suffer early mortality despite antiviral treatment, and therefore should be considered for early liver transplantation.

M1895 Hepatitis B Patients Who are Lamivudine-Resistant, Adefovir Poor-Responders May Be Selected for Entecavir Monotherapy Based on Their Pre-Treatment Resistance Substitutions - A Four-Year Cohort Study

Background: Entecavir is one of the treatment options for lamivudine-resistant hepatitis B patients though there is increased entecavir-resistance rate. The response of lamivudineresistant, adefovir poor-responders is unclear. Methods: We performed a four-year cohort study on the efficacy of entecavir 1mg/day on lamivudine-resistant patients. Enrolment criteria include: documented lamivudine resistannce mutations, HBV DNA ≥ 2x10(4)IU/ ml, ALT <1.3X upper limit of normal, and Child-Pugh score <7. Clinical outcomes, liver biochemistries, and HBVDNAweremonitored regularly every 16 weeks. Factors contributing to entecavir treatment failure were examined. Result: Fourteen Chinese patients who were lamivudine-resistant were recruited, twelve of whomwere poor-responders to adefovir rescue. Follow-up was complete at mean of 49 months. Mean HBV DNA fell from 1.03x10(7)IU/ml (baseline) to 1.35x10(2)IU/ml. The presence of rtM204V mutation (n=5) at baseline was found to be the major risk factor for entecavir failure. Compared with rtM204I (n=7) and rtA181V (n=2), rtM204V patients have high risk of virologic breakthrough requiring addon adefovir (4/5 patients), slower virologic responses, failure to reach undetectable HBV DNA levels (3/5 patients), high risk of entecavir-resistance (3/5 patients) and death (2/5 patients). All the other patients had undetectable HBV DNA by 18th month. Conclusion: Lamivudine-resistant, adefovir poor-responders can be selected for entecavir monotherapy, based on their pre-existing resistance substitutions (rtM204I and rtA181V). Those with rtM204V mutation had high risk of entecavir resistance and viral breakthrough, and could benefit from combination therapy from the start.