Hepatocellular carcinoma in a mouse model fed a choline-deficient, L-amino acid-defined, high-fat diet.

Hepatocellular carcinoma (HCC) is a common cancer worldwide and represents the outcome of the natural history of chronic liver disease. The growing rates of HCC may be partially attributable to increased numbers of people with non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH). However, details of the liver-specific molecular mechanisms responsible for the NAFLD-NASH-HCC progression remain unclear, and mouse models that can be used to explore the exact factors that influence the progression of NAFLD/NASH to the more chronic stages of liver disease and subsequent HCC are not yet fully established. We have previously reported a choline-deficient, L-amino acid-defined, high-fat diet (CDAHFD) as a dietary NASH model with rapidly progressive liver fibrosis in mice. The current study in C57BL/6J mice fed CDAHFD provided evidence for the chronic persistence of advanced hepatic fibrosis in NASH and disease progression towards HCC in a period of 36 weeks. When mice fed CDAHFD were switched back to a standard diet, hepatic steatosis was normalized and NAFLD activity score improved, but HCC incidence increased and the phenotype of fibrosis-associated HCC development was observed. Moreover, when mice continued to be fed CDAHFD for 60 weeks, HCC further developed without severe body weight loss or carcinogenesis in other organs. The autochthonous tumours showed a variety of histological features and architectural patterns including trabecular, pseudoglandular and solid growth. The CDAHFD mouse model might be a useful tool for studying the development of HCC from NAFLD/NASH, and potentially useful for better understanding pathological changes during hepatocarcinogenesis.

BUBR1 Insufficiency in Mice Increases their Sensitivity to Oxidative Stress.

BACKGROUND/AIM: Budding uninhibited by benzimidazole-related 1 (BUBR1) plays an important role in the spindle assembly checkpoint to prevent chromosome missegregation and aneuploidy during mitosis. We previously generated mutant mice that express BUBR1 at only 20% of the normal level (BubR1L/L mice). Here, we examined the effect of low BUBR1 expression on oxidative stress-induced carcinogenesis in mice. MATERIALS AND METHODS: We orally administered either a potassium bromate (KBrO3) solution (2 g/l) or tap water to BubR1L/L and wild-type (BubR1+/+)mice for 16 weeks and examined the subsequent incidence of tumours. RESULTS: KBrO3-treated BubR1L/L mice showed significantly higher mortality than the KBrO3-treated BubR1+/+ and control tap water-treated mice (p=0.0082). Histopathological and immunohistochemical analyses revealed that the spleens of surviving BubR1L/L mice were occupied by non-B-, non-T-cells with high proliferative potential. CONCLUSION: Our results indicate that low BUBR1 expression increases oxidative stress-induced mortality in mice, possibly caused by splenic neoplasms.

Correlation of HER2 expression with clinicopathological characteristics and prognosis in resectable gastric cancer.

Results from the Trastuzumab for Gastric Cancer (ToGA) trial highlighted the clinical significance of trastuzumab in the treatment of HER2 (Human Epidermal Growth Factor Receptor type 2)-positive gastric cancer. However, whether expression of HER2 is related to prognosis of gastric cancer is still controversial. A total of 360 consecutive patients with gastric cancer who underwent surgical resection in our Department from 1994 to 2007 were analyzed. We performed immunohistochemical analysis of HER2 expression. HER2 expression level was classified into four scores (0, 1+, 2+ and 3+). There were 37 (10%) patients with a score of 3+. A score of 3+ was defined as being HER2-positive. Recurrence-free survival was worse in HER2-positive cases (p=0.045). When the analysis was conducted with intestinal types of cancer, RFS was considerably worse in the HER2-positive group (p=0.011). HER2 expression may have potential as a prognostic factor for intestinal cancer types. Further research is warranted.

Aberrations of BUBR1 and TP53 gene mutually associated with chromosomal instability in human colorectal cancer.

BACKGROUND/AIM: Defects in mitotic checkpoint and p53-dependent pathways associate with chromosomal instability. In the present study, we investigated the interplay between BUBR1 and p53 and their association with genetic instability in colorectal cancer. PATIENTS AND METHODS: 139 colorectal cases were examined for BUBR1, p53 and genetic instability indicators. BUBR1 expression was evaluated by immunohistochemistry and TP53 gene was directly sequenced. DNA ploidy was studied by laser scanning cytometry; MSI and TP53 loss of heterozygosity was also examined. RESULTS: 64% of cases had high BUBR1 expression and were associated with the TP53 mutation. High BUBR1 expression and TP53 mutation associated with DNA aneuploidy and showed an inverse association with MSI. Cases with high BUBR1 expression and TP53 mutation had profound aneuploidy phenotypes and less frequent MSI compared to cases with one or neither aberration. CONCLUSION: Our findings indicated an interplay between BUBR1 and p53 in colorectal cancer. Altered expression of both molecules was associated with chromosomal instability.

Mortalin is a prognostic factor of gastric cancer with normal p53 function.

BACKGROUND: Mortalin is a heat-non-inducible member of the heat shock protein 70 family. Mortalin binds to p53 and prevents p53 from entering the nucleus. To understand the significance of mortalin in gastric cancer, we investigated the expression of mortalin and p53. METHODS: Expression of mortalin and p53 was examined by immunohistochemical staining of 182 clinical samples of gastric cancer. RESULTS: Mortalin-positive and aberrant p53-positive tumors were found in 75.2 and 49.5 % of cases, respectively. Mortalin-positive tumors were deeper in invasion and had more lymph node and liver metastases compared with mortalin-negative tumors (P < 0.01, P < 0.05, respectively). Mortalin-positive tumors had worse prognosis compared with mortalin-negative tumors (P = 0.035). Moreover, in tumors with normal p53 function, mortalin-positive tumors had worse prognosis compared with mortalin-negative tumors (P = 0.017). CONCLUSIONS: Mortalin has a great impact on gastric cancer with normal p53. Therefore, mortalin is a target molecule for treatment of gastric cancer, as well as a promising prognostic factor, especially in tumors with normal p53.

Contribution of BubR1 to oxidative stress-induced aneuploidy in p53-deficient cells.

DNA aneuploidy is observed in various human tumors and is associated with the abnormal expression of spindle assembly checkpoint (SAC) proteins. Oxidative stress (OS) causes DNA damage and chromosome instability that may lead to carcinogenesis. OS is also suggested to contribute to an increase in aneuploid cells. However, it is not clear how OS is involved in the regulation of SAC and contributes to carcinogenesis associated with aneuploidy. Here we show that an oxidant (KBrO3) activated the p53 signaling pathway and suppressed the expression of SAC factors, BubR1, and Mad2, in human diploid fibroblast MRC5 cells. This suppression was dependent on functional p53 and reactive oxygen species. In p53 knockdown cells, KBrO3 did not suppress BubR1 and Mad2 expression and increased both binucleated cells and cells with >4N DNA content. BubR1 and not Mad2 downregulation suppressed KBrO3-induced binucleated cells and cells with >4N DNA content in p53 knockdown cells, suggesting that BubR1 contributes to enhanced polyploidization by a mechanism other than its SAC function. In analysis of 182 gastric cancer specimens, we found that BubR1 expression was significantly high when p53 was positively stained, which indicates loss of p53 function (P = 0.0019). Moreover, positive staining of p53 and high expression of BubR1 in tumors were significantly correlated with DNA aneuploidy (P = 0.0065). These observations suggest that p53 deficiency may lead to the failure of BubR1 downregulation by OS and that p53 deficiency and BubR1 accumulation could contribute to gastric carcinogenesis associated with aneuploidy.

Hepatic interferon-gamma-induced protein-10 expression is more strongly associated with liver fibrosis than interleukin-28B single nucleotide polymorphisms in hepatocellular carcinoma resected patients with chronic hepatitis C.

AIM: Single nucleotide polymorphisms (SNP) around IL-28B and interferon (IFN)-stimulated gene (ISG) expression are predictors of response to standard therapy involving IFN for chronic hepatitis C virus (HCV) infection. We analyzed the association between these predictors to improve the prediction of the response to IFN therapy after liver resection for hepatocellular carcinoma (HCC). METHODS: Data were collected from 74 patients with HCV-induced HCC. The IL-28B genotype and hepatic ISG mRNA levels were analyzed to clarify their association, focusing on the progression of liver fibrosis. RESULTS: Fifty patients were identified as having major alleles (rs8099917 TT) and the remaining 24 patients had minor alleles (rs8099917 TG or GG). Hepatic ISG15 expression was lower in the IL-28B major group than that in the IL-28B minor group (P < 0.005). IP-10 expression was similar between the IL-28B major and minor groups (P = 0.44). IP-10 expression was elevated with advancing stages of liver fibrosis in HCV infected patients (P = 0.005). In patients with mild or no fibrosis, the IL-28B major group had lower IP-10 expression than the IL-28B minor group (P = 0.02). However, in patients with advanced fibrosis, IP-10 expression was not different between the IL-28B major and minor groups (P = 0.66). CONCLUSION: Hepatic ISG15 expression is associated with IL-28B polymorphisms, while IP-10 is strongly affected by liver fibrosis.