Hepatocarcinogenesis in rodents and humans

Identification of candidate lung cancer susceptibility genes in mouse using oligonucleotide arrays

We applied microarray gene expression profiling to lungs from mouse strains having variable susceptibility to lung tumour development as a means to identify, within known quantitative trait loci (QTLs), candidate genes responsible for susceptibility or resistance to lung cancer. At least eight chromosomal regions of mice have been mapped and verified to be linked with lung tumour susceptibility or resistance. In this study, high density oligonucleotide arrays were used to measure the relative expression levels of >36 000 genes and ESTs in lung tissues of A/J, BALB/cJ, SM/J, C3H/HeJ, and C57BL/6J mice. A number of differentially expressed genes were found in each of the lung cancer susceptibility QTLs. Bioinformatic analysis of the differentially expressed genes located within QTLs produced 28 susceptibility candidates and 22 resistance candidates. These candidates may be extremely helpful in the ultimate identification of the precise genes responsible for lung tumour susceptibility or resistance in mice and, through follow up, humans. Complete data sets are available at http://thinker.med.ohio-state.edu.

A novel gene "Niban" upregulated in renal carcinogenesis: cloning by the cDNA-amplified fragment length polymorphism approach

A modified AFLP (amplified fragment length polymorphism) method was employed to isolate genes differentially expressed in renal carcinogenesis of Tsc2 gene mutant (Eker) rats. One gene, selected for further investigation, was named "Niban" "second" in Japanese), because it is the second new gene to be found after Erc (expressed in renal carcinoma) in our laboratory. Importantly, "Niban" is well expressed even in small primary rat Eker renal tumors, more than in progressed cell lines, and is also expressed in human renal carcinoma cells, but not in normal human or rat kidneys. Chromosome assignment was to RNO 13 in the rat, and HSA 1. This "Niban" gene is a candidate as a marker for renal tumor, especially early-stage renal carcinogenesis.

Frequent rearrangements at minisatellite loci D1S7 (1p33-35), D7S22 (7q36-ter) and D12S11 (12q24.3-ter) in hepatitis B virus-positive hepatocellular carcinomas from Thai patients

Primary hepatocellular carcinoma (HCC) is one of the most common cancers in Thailand; chronic infection with hepatitis B virus (HBV) is endemic and represents a major risk factor for the development of this cancer. Several mechanisms for HBV-related hepatocarcinogenesis have been proposed, among them a direct role of HBV in the promotion of genetic recombination leading to chromosomal alterations. Minisatellite DNA sequences are hypervariable regions dispersed throughout the genome which are susceptible to genetic recombination events. In the present study, somatic rearrangements affecting minisatellite sequences were examined in a total of 26 HCC from Thai patients. Multilocus DNA fingerprinting using probes 33.15 and 33.6 detected rearrangements in 11 and 12 HCC, respectively, all of them carrying integrated HBV DNA. The frequency of rearranged bands was calculated for each probe based on the total number of rearrangements observed in the 26 tumours and the total number of bands revealed by DNA fingerprinting in the non-tumour DNA. With each probe a total of 23 rearrangements was observed, yielding rearrangement frequencies of 3.7% and 4.2% for the 33.15 and 33.6 minisatellite families, respectively. To test for possible clustering of these rearrangements at specific loci, we used minisatellite locus-specific probes previously cloned from 33.15 and 33.6. Minisatellites located at 1p33-35, 7q36-ter and 12q24.3-ter were shown to be frequently affected by rearrangement events in this series of HBV-positive HCC. Frequent rearrangements at minisatellite locus D7S22 (7q36-ter) in HBV-positive human HCC have not been reported so far.