Mice lacking bi-1 gene show accelerated liver regeneration

The liver has enormous regenerative capacity such that, after partial hepatectomy, hepatocytes rapidly replicate to restore liver mass, thus providing a context for studying in vivo mechanisms of cell growth regulation. Bax inhibitor-1 (BI-1) is an evolutionarily conserved endoplasmic reticulum (ER) protein that suppresses cell death. Interestingly, the BI-1 protein has been shown to regulate Ca(2+) handling by the ER similar to antiapoptotic Bcl-2 family proteins. Effects on cell cycle entry by Bcl-2 family proteins have been described, prompting us to explore whether bi-1-deficient mice display alterations in the in vivo regulation of cell cycle entry using a model of liver regeneration. Accordingly, we compared bi-1(+/+) and bi-1(-/-) mice subjected to partial hepatectomy with respect to the kinetics of liver regeneration and molecular events associated with hepatocyte proliferation. We found that bi-1 deficiency accelerates liver regeneration after partial hepatectomy. Regenerating hepatocytes in bi-1(-/-) mice enter cell cycle faster, as documented by more rapid incorporation of deoxynucleotides, associated with earlier increases in cyclin D1, cyclin D3, cyclin-dependent kinase (Cdk) 2, and Cdk4 protein levels, more rapid hyperphosphorylation of retinoblastoma protein, and faster degradation of p27(Kip1). Dephosphorylation and nuclear translocation of nuclear factor of activated T cells 1 (NFAT1), a substrate of the Ca(2+)-sensitive phosphatase calcineurin, were also accelerated following partial hepatectomy in BI-1-deficient hepatocytes. These findings therefore reveal additional similarities between BI-1 and Bcl-2 family proteins, showing a role for BI-1 in regulating cell proliferation in vivo, in addition to its previously described actions as a regulator of cell survival.     

Cigarette smoke components inhibited intercellular communication and differentiation in human pancreatic ductal epithelial cells

Smoking is a well-documented risk factor for the development of pancreatic adenocarcinoma. Although the most abundant polycyclic aromatic hydrocarbons (PAHs) in cigarette smoke are methylated anthracenes and phenanthrenes, the epigenetic toxicity of these compounds has not been extensively studied. We previously showed that methylanthracenes, which possess a bay-like structure, affect epigenetic events such as an induced release of arachidonic acid, inhibition of gap junctional intercellular communication (GJIC) and induction of mitogen-activated protein kinases in a pluripotent rat liver epithelial stem cell line. Anthracenes with no bay-like structures were inactive. These biological effects are all molecular events associated with the promotional phase of cancer. A human immortalized, nontumorigenic pancreatic ductal epithelial cell line, H6c7, was examined to study the epigenetic toxicity of PAHs related to pancreatic cancer by using scrape-loading dye transfer, immunostaining, RT-PCR and telomerase assay methods. H6c7 cells were GJIC-incompetent and exhibited high telomerase activity when grown in growth factor and hormone-supplemented medium. In the presence of the cAMP elevating drugs (forskolin and IBMX) the cells became GJIC competent and expressed connexins. Telomerase activity was also decreased by cAMP elevating drug treatment. After induction of cAMP, 1-methylanthracene with bay-like structures inhibited GJIC, whereas the 2-methylanthracene lacking a bay-like structure had no effect on GJIC. Telomerase activity remained high in 1-methylanthracene treatment but not with 2-methylanthracene. These results indicate that a prominent component of cigarette smoke, namely methylanthracenes with distinct structural configurations, could be a potential etiological agent contributing to the epigenetic events of pancreatic cancer.     

Influence of VEGF-A gene variation and protein levels in breast cancer susceptibility and severity

Vascular endothelial growth factor-A (VEGF-A) plays an important role in tumour angiogenesis and cancer progression. VEGF gene variation may influence VEGF levels and therefore cancer susceptibility and progression. We studied the role of VEGF single nucleotide polymorphisms and haplotypes in breast cancer susceptibility and severity. We also studied the relationships of VEGF SNPs with circulating VEGF levels in healthy volunteers and protein expression in breast cancers. Single nucleotide polymorphisms (SNPs) in the regulatory regions of the VEGF gene were genotyped by high throughput methods in approximately 500 breast cancer cases and 500 appropriate controls. Haplotype frequencies were inferred using methods based on the Expectation Maximisation algorithm. The effect of VEGF genotypes on serum and plasma VEGF levels were studied in another cohort of healthy individuals. A semi-quantitative assessment of VEGF protein expression on tissue micro arrays (TMA) constructed from approximately 300 breast cancer samples was performed and compared with VEGF genotypes and with histopathological parameters and survival in breast cancer. The -460T/+405C/-7C/936C haplotype in the VEGF gene was found to be associated with decreased breast cancer risk (p = 0.029). The -7C>T polymorphism may influence overall breast cancer survival (p = 0.027). Individual polymorphisms however did not affect breast cancer susceptibility. There was no association between the individual polymorphisms and circulating VEGF levels in healthy volunteers and VEGF expression on the breast cancer micro array. VEGF expression in breast cancers was however associated with high grade (p = 0.002) and ER negative tumours (p = 0.03).     

A novel duplex SSP–PCR typing method for KIR gene profiling

Killer-cell immunoglobulin-like receptors (KIR) control the function of natural killer cells. The number and type of KIR genes are substantially variable among individuals. Sequence-specific primer–directed polymerase chain reaction (SSP-PCR) based genotyping is the most commonly used method to assess the KIR gene content. However, it requires a minimum of 16 gene-specific amplifications and often yields false-negative results. Herein, we describe the development of a simple and efficient duplex SSP-PCR assay to identify the presence and absence of 16 KIR genes. This system further distinguishes subsets of KIR2DS4 and KIR3DP1 alleles. The assay was subjected to a blind validation using a panel of 78 reference DNA standards from the UCLA KIR Exchange Program, which showed 100% specificity and accuracy. Compared with the conventional SSP typing methods, the present method is an accurate, simple, cost-effective and labor-saving KIR genotyping method for high volume testing.     

Genotyping as a diagnostic aid in genetic haemochromatosis

BACKGROUND: Two mutations in a newly described gene, HFE, have been proposed as genetic markers for the inherited iron overload disease, genetic haemochromatosis. METHODS: We assessed the frequency of both mutations in a cohort of genetic haemochromatosis patients and compared these with a control population. The patients were genetic haemochromatosis patients from Western Australia whose diagnosis met strict criteria for phenotypic expression. Control patients had other liver disease where iron overload was excluded. RESULTS: Genomic DNA of 72 genetic haemochromatosis patients and 69 controls was examined for the C282Y and H63D mutations of the HFE gene using polymerase chain reaction amplification and restriction enzyme digestion. In genetic haemochromatosis patients, the C282Y mutation was homozygous in 64 of 72, giving a sensitivity of 89% (95% confidence interval 82-96%), heterozygous in five (7%) and absent in another three (4%), whereas none of the control subjects were homozygous. The H63D mutation was present in one genetic haemochromatosis patient and was not useful as a diagnostic marker. In this cohort of Western Australian patients with phenotypic expression of genetic haemochromatosis, the specificity of a homozygous C282Y mutation for genetic haemochromatosis was 100%. CONCLUSIONS: The results indicate that genotyping for the C282Y mutation is a useful test for the diagnosis of genetic haemochromatosis in clinical practice.