Lamivudine is a potent inhibitor of hepatitis B virus (HBV) replication, but its long‐term use may be associated with HBV tyrosine‐methionine‐aspartate‐aspartate (YMDD) motif mutation. To examine the ...clinical features and course after emergence of YMDD mutants, 55 patients who received lamivudine therapy over 104 weeks at our unit were assayed for YMDD mutation(s). Thirty‐two of them were found to have the YMDD mutation. They continued lamivudine therapy and were followed up weekly or biweekly if clinically indicated. Thirty (93.7%) of them showed elevation of alanine transaminase (ALT), and 13 (40.6%) experienced acute exacerbation at 4 to 94 weeks (median, 24 weeks) after emergence of the YMDD mutant. The incidence of exacerbation is much higher than 4.3% in patients without the YMDD mutation (P = .003). Compared with patients without exacerbation, patients with exacerbation had a significantly higher serum HBV‐DNA level after emergence of the YMDD mutant (P < .005). Before exacerbation, serum HBV‐DNA level was rising to its peak, followed by the peaking of ALT (247‐2,010 U/L) 1 to 4 weeks later. Three patients developed hepatic decompensation, but then in association with hepatitis B e antigen (HBeAg) seroconversion, recovered. Of the 12 evaluable patients, 8 (75%) showed HBeAg seroconversion, and 3 showed mutant clearance within 1 to 5 months after exacerbation. In contrast, none of the patients without exacerbation showed HBeAg seroconversion (P < .001). These results indicate that acute exacerbations may occur after emergence of the YMDD mutation. The incidence, clinicopathological features, and subsequent course, and possibly the underlying immune mechanisms, are similar to those of wild‐type HBV chronic infection. Because severe hepatitis may occur, patients should be followed carefully once the YMDD mutant emerges.
Aciculatin, a natural compound extracted from the medicinal herb Chrysopogon aciculatus, shows potent anti-cancer potency. This study is the first to prove that aciculatin induces cell death in human ...cancer cells and HCT116 mouse xenografts due to G1 arrest and subsequent apoptosis. The primary reason for cell cycle arrest and cell death was p53 accumulation followed by increased p21 level, dephosphorylation of Rb protein, PUMA expression, and induction of apoptotic signals such as cleavage of caspase-9, caspase-3, and PARP. We demonstrated that p53 allele-null (-/-) (p53-KO) HCT116 cells were more resistant to aciculatin than cells with wild-type p53 (+/+). The same result was achieved by knocking down p53 with siRNA in p53 wild-type cells, indicating that p53 plays a crucial role in aciculatin-induced apoptosis. Although DNA damage is the most common event leading to p53 activation, we found only weak evidence of DNA damage after aciculatin treatment. Interestingly, the aciculatin-induced downregulation of MDM2, an important negative regulator of p53, contributed to p53 accumulation. The anti-cancer activity and importance of p53 after aciculatin treatment were also confirmed in the HCT116 xenograft models. Collectively, these results indicate that aciculatin treatment induces cell cycle arrest and apoptosis via inhibition of MDM2 expression, thereby inducing p53 accumulation without significant DNA damage and genome toxicity.
There are inconsistent data on the durability of hepatitis B e antigen (HBeAg) seroconversion after lamivudine is discontinued. The aim of this study was to examine the determinants for sustained ...HBeAg response to lamivudine therapy. Both host and viral factors as well as the drug factor were compared between 43 patients with sustained HBeAg response and 39 patients whose response was not sustained. All of them received a mean period of 16 months (range, 3–55 months) lamivudine therapy and had achieved complete response (HBeAg seroconversion plus HBV DNA seroclearance by hybrid capture assay and normal alanine aminotransferase ALT) and were followed-up for a mean period of 44 months (range, 12–88 months). Stepwise logistic regression model was used to estimate the sustained response on the presence of the following variables: age; gender; pretherapy ALT; total bilirubin and HBV DNA levels; time to HBeAg seroconversion; additional lamivudine treatment after HBeAg seroconversion; total duration of treatment; hepatitis activity index scores; periportal, intralobular, and portal inflammation and fibrosis scores; scores excluding fibrosis; status of precore mutation; basal core promoter mutation; and genotype. The results showed that genotype (OR, 5.922; 95% CI, 1.611–21.768;
P = .007), age (OR, 0.943; 95% CI, 0.891–0.997;
P = .040), and additional treatment (OR, 1.097; 95% CI, 1.028–1.171;
P = .005) were independent factors to sustained HBeAg response. Further categorical analysis disclosed that patients with genotype B, age ≤36 years, and additional lamivudine treatment over 8 months have higher sustained response. In conclusion, HBV genotype, age, and additional treatment are the major determinants for the sustained HBeAg response to lamivudine therapy.
TNFα has recently emerged as a regulator linking inflammation to cancer pathogenesis, but the detailed cellular and molecular mechanisms underlying this link remain to be elucidated. The tuberous ...sclerosis 1 (TSC1)/TSC2 tumor suppressor complex serves as a repressor of the mTOR pathway, and disruption of TSC1/TSC2 complex function may contribute to tumorigenesis. Here we show that IKKβ, a major downstream kinase in the TNFα signaling pathway, physically interacts with and phosphorylates TSC1 at Ser487 and Ser511, resulting in suppression of TSC1. The IKKβ-mediated TSC1 suppression activates the mTOR pathway, enhances angiogenesis, and results in tumor development. We further find that expression of activated IKKβ is associated with TSC1 Ser511 phosphorylation and VEGF production in multiple tumor types and correlates with poor clinical outcome of breast cancer patients. Our findings identify a pathway that is critical for inflammation-mediated tumor angiogenesis and may provide a target for clinical intervention in human cancer.
Epithelial-to-mesenchymal transition (EMT) is an essential physiologic process that promotes cancer cell migration, invasion, and metastasis. Several lines of evidence from both cellular and genetic ...studies suggest that AKT1/PKBα, but not AKT2 or AKT3, serves as a negative regulator of EMT and breast cancer metastasis. However, the underlying mechanism by which AKT1 suppresses EMT remains poorly defined. Here, we demonstrate that phosphorylation of Twist1 by AKT1 is required for β-TrCP-mediated Twist1 ubiquitination and degradation. The clinically used AKT inhibitor MK-2206, which possesses higher specificity toward AKT1, stabilized Twist1 and enhanced EMT in breast cancer cells. However, we discovered that resveratrol, a naturally occurring compound, induced β-TrCP-mediated Twist1 degradation to attenuate MK-2206-induced EMT in breast cancer cells. Taken together, our findings demonstrate that resveratrol counteracts the unexpected metastatic potential induced by anti-AKT therapy and therefore suggest that the addition of resveratrol to an anti-AKT therapeutic regimen may provide extra support for limiting EMT.
Abstract Attacking angiogenesis is considered an effective strategy for controls the expansion and metastasis of tumors and other related-diseases. The aim of this study was to assess the effects of ...moscatilin, a bibenzyl derivative, on VEGF and bFGF-induced angiogenesis in cultured human umbilical vein endothelial cells (HUVECs) in vitro and in vivo . Moscatilin significantly inhibited growth of lung cancer cell line A549 (NSCLC) and suppressed growth factor-induced neovascularization. In addition, VEGF- and bFGF-induced cell proliferation, migration, and tube formation of HUVECs was markedly inhibited by moscatilin. Western blotting analysis of cell signaling molecules indicated that moscatilin inhibited ERK1/2, Akt, and eNOS signaling pathways in HUVECs. These results suggest that inhibition of angiogenesis by moscatilin may be a major mechanism in cancer therapy.
Chemotherapeutic drugs are usually designed to induce cancer cell death via cell cycle arrest and/or apoptosis pathways. In this study, we used the chemical drug 15,16-dihydrotanshinone I (DHTS) to ...inhibit breast cancer cell proliferation and tumor growth, and investigate the underlying molecular mechanisms. Human breast cancer cell lines MCF-7 and MDA-MB-231 were both used in this study, and DHTS was found to significantly decrease cell proliferation by a dose-dependent manner in both cells. Flow cytometry indicated that DHTS induced G1 phase arrest in synchronous MCF-7 and MDA-MB-231 cells. When analyzing the expression of cell cycle-related proteins, we found that DHTS reduced cyclin D1, cyclin D3, cyclin E, and CDK4 expression, and increased CDK inhibitor p27 expression in a dose-dependent manner. In addition, DHTS inhibited the kinase activities of CDK2 and CDK4 by an immunocomplex kinase assay. In addition, DHTS also induced apoptosis in both cells through mainly mitochondrial apoptosis pathways. We found that DHTS decreased the anti-apoptotic protein Bcl-xL level and increased the loss of mitochondria membrane potential and the amount of cytochrome
c released. Moreover, DHTS activated caspase-9, caspase-3, and caspase-7 and caused cell apoptosis. The fact that DHTS-induced apoptosis could be blocked by pretreating cells with pan-caspase inhibitor confirmed that it is mediated through activation of the caspase-3-dependent pathway. In a nude mice xenograft experiment, DHTS significantly inhibited the tumor growth of MDA-MB-231 cells. Taken together, these results suggest that DHTS can inhibit human breast cancer cell proliferation and tumor growth, and might have potential chemotherapeutic applications.
Up-regulation of Wnt-1 protein has been reported in hepatitis B virus (HBV)-related and hepatitis C virus (HCV)-related hepatocellular carcinoma (HCC) tissues and cell lines. It is known to play a ...fundamental role in signaling cancer progression, whereas its prognostic role in HCC remains unexplored.
As a prognostic biomarker, this study analyzed Wnt-1 protein expression in 63 histology-verified HCC patients receiving curative resection. In each paired tumor and nontumor specimen, Wnt-1 levels were semiquantitatively measured by Western blotting and expressed by tumor/nontumor ratio. The data were further correlated with quantitative real-time PCR as well as with beta-catenin and E-cadherin expression by immunohistochemistry. Cumulative tumor recurrence-free survival curves were constructed using the Kaplan-Meier method and compared by the log-rank test.
The results showed that 26 (group I) and 37 (group II) HCC patients had an expression ratio of Wnt-1 > or =1.5 and <1.5, respectively. The amount of Wnt-1 estimated by tumor/nontumor ratio correlated with the results by quantitative real-time PCR. High tumor Wnt-1 expression correlated with enhanced nuclear beta-catenin accumulation, diminished membranous E-cadherin expression, and increased tumor recurrence after curative tumor resection.
These results suggest that Wnt-1 may be used as a predisposing risk factor for HCC recurrence. The use of tumor Wnt-1 as prognostic biomarker may identify patients with HBV- and/or HCV-related HCC patients with a high risk of tumor recurrence who may then benefit from further intensive therapy after surgery.
CHM-1 (2′-fluoro-6,7-methylenedioxy-2-phenyl-4-quinolone) has been identified as a potent antitumor agent in human hepatocellular carcinoma; however, its role in tumor angiogenesis is unclear. This ...study investigated the effects of CHM-1 and the mechanisms by which it exerts its antiangiogenic and vascular disrupting properties. Using a xenograft model antitumor assay, we found that CHM-1 significantly inhibits tumor growth and microvessel formation. Flow cytometry, immunofluorescence microscopy, and cell death enzyme-linked immunosorbent assay kit revealed that CHM-1 inhibits growth of human umbilical vein endothelial cells (HUVEC) by induction of apoptotic cell death in a concentration-dependent manner. CHM-1 also suppresses HUVEC migration and capillary-like tube formation. We were able to correlate CHM-1-induced apoptosis in HUVEC with the cleavage of procaspase-3, -7, and -8, as well as with the cleavage of poly(ADP-ribose) polymerase by Western blotting assay. Such sensitization was achieved through up-regulation of death receptor 5 (DR5) but not DR4 or Fas. CHM-1 was also capable of increasing the expression level of p53, and most importantly, the induction of DR5 by CHM-1 was abolished by p53 small interfering RNA. Taken together, the results of this study indicate that CHM-1 exhibits vascular targeting activity associated with the induction of DR5-mediated endothelial cell apoptosis through p53 up-regulation, which suggests its potential as an antivascular and antitumor therapeutic agent.
PDF
