Benjamin Chun-Yu Wong

Independent risk factors and predictive score for the development of hepatocellular carcinoma in chronic hepatitis B

BACKGROUND/AIMSnTo determine whether gender, age, hepatitis B virus genotype, core promoter and precore mutations, HBeAg/ anti-HBe status, HBV DNA, ALT levels and cirrhosis on presentation were independent risk factors and derive a novel risk score for the development of HCC.nnnMETHODSnCHB patients (820) were followed up (mean duration 76.8 months) for the occurrence of HCC.nnnRESULTSnThe 5- and 10-year prevalence of HCC were 4.4% and 6.3%, respectively. Cox regression analysis showed that male gender (p = 0.025, RR 2.98), increasing age (p < 0.001, RR 1.07), higher HBV DNA levels (p = 0.02, RR 1.28), core promoter mutations (p = 0.007, RR 3.66), and presence of cirrhosis (p < 0.001, RR 7.31) were independent risks for the development of HCC. A risk score was derived and validated with sensitivity > 84% and specificity > 76% to predict the 5- and 10- year risks for the development of HCC. The AUC for the 5- and 10-year prediction were 0.88 and 0.89, respectively.nnnCONCLUSIONSnThe risk score, based on age, gender, HBV DNA levels, core promoter mutations and cirrhosis, can estimate the chance of development of HCC in 5 and 10 years after presentation. It can be used to identify high-risk CHB patients for treatment and screening of HCC.

Functional p53 is required for triptolide-induced apoptosis and AP-1 and nuclear factor-κB activation in gastric cancer cells

Triptolide, a major component in the extract of Chinese herbal plant Tripterygium wilfordii Hook f (TWHf), has potential anti-neoplastic effect. In the present study we investigated the potential therapeutic effects and mechanisms of triptolide against human gastric cancer cells. Four gastric cancer cell lines with different p53 status, AGS and MKN-45 (wild type p53); MKN-28 and SGC-7901 (mutant p53) were observed as to cell growth inhibition and induction of apoptosis in response to triptolide treatment. We showed that triptolide inhibited cell growth, induced apoptosis and suppressed NK-κB and AP-1 transactivation in AGS cells with wild-type p53. Triptolide induced apoptosis by stimulating the expressions of p53, p21waf1/cip1, bax protein, and increased the activity of caspases. In addition, it caused cell cycle arrest in the G0/G1 phase. To examine the role of p53 in these functions, we showed that suppression of p53 level with antisense oligonucleotide abrogated triptolide-induced apoptosis and over-expression of dominant negative p53 abolished the inhibitory effect on NF-κB activation. Furthermore, we demonstrated that triptolide had differential effects on gastric cancer cells with different p53 status. We showed that triptolide also inhibited cell growth and induced apoptosis in MKN-45 with wild-type p53, whereas it had no significant growth-inhibition and apoptosis induction effects on the MKN-28 and SGC-7901 cells with mutant p53. Our data suggest that triptolide exhibits anti-tumor and anti-inflammatory effects by inhibiting cell proliferation, inducing apoptosis and inhibiting NF-κB and AP-1 transcriptional activity. However, a functional p53 is required for these proapoptotic, anti-inflammatory and anti-tumor effects.

Histogenesis of human colorectal adenomas and hyperplastic polyps: the role of cell proliferation and crypt fission

Background: The histogenesis of human colorectal hyperplastic polyps and colorectal adenomas is poorly understood even now. Method: Human colorectal adenomas, hyperplastic polyps, and normal colorectal mucosae (patients with familial adenomatous polyposis and hereditary non-polyposis colorectal carcinoma were excluded) were obtained during colonoscopy and microdissected into individual crypts. Morphology, cell proliferation characteristics, and fission indices of crypts isolated from these lesions were then studied. Results: Crypts isolated from colorectal adenomas and colorectal hyperplastic polyps were significantly larger (p<0.001) than crypts from normal colorectal mucosae. Crypt fission was an uncommon event in normal colonic mucosae but common in crypts isolated from adenomas and hyperplastic polyps (p<0.001). Analysis of the distribution of mitoses suggested an upward expansion of the proliferation compartment in adenomas to the surface of the crypt with no reversal of proliferating cell distribution, as has previously been described. Conclusions: Sporadic human colorectal adenomas and hyperplastic polyps grow by the process of crypt fission. Expansion of the proliferative compartment was demonstrated in crypts from adenomas, consistent with deregulation of cell cycle control.

Arsenic trioxide induces apoptosis in human gastric cancer cells through up‐regulation of P53 and activation of caspase‐3

Arsenic trioxide (As2O3) can induce clinical remission in patients suffering from acute promyelocytic leukemia, through induction of apoptosis and activation of caspases. We investigated the potential use of As2O3 in human gastric cancer and its possible mechanisms. Human gastric cancer cell lines AGS and MKN‐28 were treated with various concentrations (0.1 to 100 μM) of As2O3 for 24 to 72 hr. Apoptosis was determined by acridine orange staining, flow cytometry and DNA fragmentation. Protein levels of p53, p21waf1/cip1, c‐myc, bcl‐2 and bax were detected by Western blotting. Effects of As2O3 on caspase‐3 protease activity, its protein concentration and cleavage of poly(ADP)‐ribose polymerase (PARP) were also studied. As2O3 inhibited cell growth and induced apoptosis in both cell lines, though AGS cells were more sensitive. As2O3 induced apoptosis in AGS cells in a concentration‐ and time‐dependent manner. Treatment resulted in a marked increase in p53 protein levels as early as 4 hr. Co‐incubation with p53 anti‐sense oligo‐nucleotide suppressed As2O3‐induced intracellular p53 over‐expression and apoptosis. As2O3 increased the activity of caspase‐3, with appearance of its 17 kDa peptide fragment, and cleavage of PARP, with appearance of the 85 kDa cleavage product, both in parallel with the induction of apoptosis. Both the tripeptide caspase inhibitor zVAD‐fmk and the specific caspase‐3 inhibitor DEVD‐fmk partially suppressed As2O3‐induced caspase‐3 activation and apoptosis. As2O3 inhibits cell growth and induces apoptosis in gastric cancer cells, involving p53 over‐expression and activation of caspase‐3. The potential use of this compound in the treatment of gastric cancer is worth further investigation.

A large population study of spontaneous HBeAg seroconversion and acute exacerbation of chronic hepatitis B infection: implications for antiviral therapy

Background and aim: Clinical data on spontaneous hepatitis B e antigen (HBeAg) seroconversion and acute exacerbation of chronic hepatitis B (CHB) virus infection from large population studies are lacking. In the present study we examined the clinical features and significance of HBeAg seroconversion and acute exacerbation in 3063 Chinese CHB patients. Methods: Clinical assessment, liver biochemistry, hepatitis B virus (HBV) serology and HBV DNA, time of HBeAg seroconversion, and acute exacerbation were monitored. Results: Median age at HBeAg seroconversion was 34.5 years. The cumulative HBeAg seroconversion rate significantly increased with alanine aminotransferase (ALT) levels on presentation (p<0.0001). For patients with ALT levels more than twice the upper limit of normal (ULN) on presentation, the HBeAg seroconversion rate at the fifth year of follow up was 72.4%. After HBeAg seroconversion, 65.2% (73/110) of patients had undetectable HBV DNA levels by the Digene Hybrid Capture assay. Of these, 78.1% still had HBV DNA levels detectable by the Amplicor HBV Monitor Test. We found that 37.5% antibody to HBeAg (anti-HBe) positive patients had undetectable HBV DNA levels by the Digene Hybrid Capture assay before acute exacerbation. Acute exacerbations of longer duration, with higher peak ALT, bilirubin, and α fetoprotein levels were associated with an increased HBeAg seroconversion rate (p<0.0001–0.045). Acute exacerbation with peak ALT levels more than five times the ULN carried a 46.4% chance of HBeAg seroconversion within three months. HBeAg seroreversion and mortality occurred in 2.7% and 0.7% of acute exacerbations, respectively. Conclusion: In the present study we have provided information on HBeAg seroconversion and acute exacerbation, which are important in decision making for CHB treatment and in designing clinical trials.

Novel target for induction of apoptosis by cyclo-oxygenase-2 inhibitor SC-236 through a protein kinase C-β 1 -dependent pathway

Nonsteroidal anti-inflammatory drugs (NSAIDs) reduce the risk of gastrointestinal cancers. Recently, a similar protective effect has been demonstrated by the specific cyclo-oxygenase-2 (COX-2) inhibitors. However, the exact mechanism that accounts for the anti-proliferative effect of specific COX-2 inhibitors is still not fully understood, and it is still controversial whether these protective effects are predominantly mediated through the inhibition of COX-2 activity and prostaglandin synthesis. Identification of molecular targets regulated by COX-2 inhibitors could lead to a better understanding of their pro-apoptotic and anti-neoplastic activities. In the present study, we investigated the effect and the possible molecular target of a COX-2-specific inhibitor SC-236 on gastric cancer. We showed that SC-236 induced apoptosis in gastric cancer cells. However, this effect was not dependent on COX-2 inhibition. SC-236 down-regulated the protein expression and kinase activity of PKC-β1, increased the expression of PKCδ and PKCη, but did not alter the expression of other PKC isoforms in AGS cells. Moreover, exogenous prostaglandins or PGE2 receptor antagonists could not reverse the inhibition effect on PKCβ1 by SC-236, which suggested that this effect occurred through a mechanism independent of cyclo-oxygenase activity and prostaglandin synthesis. Overexpression of PKCβ1 attenuated the apoptotic response of AGS cells to SC-236 and was associated with overexpression of p21waf1/cip1. Inhibition of PKCβ1-mediated overexpression of p21waf1/cip1 partially reduced the anti-apoptotic effect of PKCβ1. The down-regulation of PKCβ1 provides an explanation for COX-independent apoptotic effects of specific COX-2 inhibitor in cultured gastric cancer cells. We also suggest that PKCβ1 act as survival mediator in gastric cancer, and its down-regulation by COX-2 inhibitor SC-236 may provide new target for future treatment of gastric cancer.

Relationship between the Development of Precore and Core Promoter Mutations and Hepatitis B e Antigen Seroconversion in Patients with Chronic Hepatitis B Virus

Chinese patients with chronic hepatitis B virus (332 with and 44 without cirrhosis-related complications) were studied. Fifty percent of patients <30 years old had precore mutations. The prevalence of precore mutations among hepatitis B e antigen (HBeAg)-positive patients, although lower than that among anti-HBe-positive patients (P=.031), was already high (44.2%). Median HBV DNA level in anti-HBe-positive patients was 1.5 x 10(6)-1.55 x 10(6) copies/mL, irrespective of the presence or absence of precore mutations. There was no difference in the prevalence of precore mutations between patients with and without complications (P, not significant). However the prevalence of core promoter mutations was higher among patients with complications than among those without complications (90.5% vs. 69.3%, respectively; P=.003). In conclusion, precore mutations occurred in a large proportion of Chinese patients with chronic hepatitis B virus before HBeAg seroconversion. The development of complications was not related to precore mutations but was probably due to the persistence of significant viremia after HBeAg seroconversion.

Interferon and Ribavirin Therapy for Chronic Hepatitis C Virus Genotype 6: A Comparison with Genotype 1

Because there is a lack of data on the treatment outcome of patients who carry hepatitis C virus (HCV) genotype 6, we conducted a prospective study, to compare the effect of interferon and ribavirin therapy in HCV genotypes 1 and 6, of patients with seropositive anti-HCV, persistently elevated alanine transaminase levels, and detectable HCV RNA. Patients were treated with subcutaneous recombinant interferon alpha-2b and ribavirin for 12 months. Of 40 patients, 16 had genotype 6, and 24 had genotype 1. An end-of-treatment response was detected in 12 (75%) patients with genotype 6 and in 10 (41.6%) patients with genotype 1 (P=.05). A sustained virological response (SVR) was present in 10 (62.5%) patients with genotype 6 and in 7 (29.2%) patients with genotype 1 (P=.04). Genotype 6 has a better response than genotype 1 and is associated with a higher SVR.

Aspirin inhibits the growth of Helicobacter pylori and enhances its susceptibility to antimicrobial agents

Background and aim: The role of Helicobacter pylori and aspirin in peptic ulcer formation and recurrence remains an important clinical topic. The interaction between aspirin and H pylori in vitro is also not clear. We investigated the effect of aspirin on the growth of H pylori and on the susceptibility of H pylori to antimicrobials. Methods: Time killing studies of H pylori were performed with different concentrations of aspirin and salicylate. Growth of bacteria was assessed spectrophotometrically and by viable colony count. The effects of aspirin on the efficiency of colony formation and on metronidazole induced mutation to rifampicin resistance in H pylori were determined. Minimal inhibitory concentrations (MICs) of aspirin and metronidazole were tested by the standard agar dilution method. MICs of amoxycillin and clarithromycin were determined by the E test method. Results: Aspirin and salicylate inhibited the growth of H pylori in a dose dependent manner and bactericidal activity was due to cell lysis. Aspirin 400 μg/ml caused a 2 logs decrease in colony forming units/ml at 48 hours, and suppressed the normal ability of metronidazole to induce new mutations to rifampicin. The IC90 of aspirin was 512 μg/ml. Increased susceptibility of amoxycillin, clarithromycin, and metronidazole to H pylori was observed at 1 mM (180 μg/ml) aspirin. Conclusions: Aspirin inhibited the growth of H pylori, suppressed the mutagenic effect of metronidazole, and enhanced the susceptibility of H pylori to antimicrobial agents. This mechanism is important in future drug development for effective clearing and overcoming resistance.

Treatment of Helicobacter pylori in patients with duodenal ulcer hemorrhage: A long-term randomized, controlled study

OBJECTIVE:Eradication of Helicobacter pylori (H. pylori) in patients with uncomplicated duodenal ulcers prevents long-term recurrence of ulcers. We aimed to study whether treatment of H. pylori prevents the long-term recurrence of duodenal ulcer hemorrhage.METHODS:Patients with duodenal ulcer bleeding and confirmed H. pylori infection were recruited. A total of 120 patients were randomly assigned to triple therapy (DeNoltab 120 mg, amoxycillin 500 mg, and metronidazole 300 mg four times daily) or DeNoltab 120 mg four times daily alone. No maintenance therapy was given during the follow-up period. The endpoints were the cumulative rates of symptomatic and bleeding duodenal ulcer recurrences.RESULTS:Of the patients receiving the triple regimen, 85.1% had H. pylori eradicated as compared to 2.0% of patients receiving DeNoltab (p < 0.05). More patients in the DeNoltab group than those in the Triple group had recurrence of ulcer bleeding, but this did not reach statistical significance (12/60 vs 6/60, p = 0.20). Logistic regression analysis on clinical, personal, and endoscopic characteristics identified persistent H. pylori infection as the only independent predictor of recurrence of duodenal ulcer bleeding.CONCLUSIONS:Treatment of H. pylori alone with the present bismuth-based triple therapy in patients with duodenal ulcer hemorrhage did not result in significant reduction in further bleeding episodes, although a trend was seen for the group that was given triple therapy. On the other hand, posttreatment H. pylori status was found to be an independent predictor of bleeding recurrence.