Our results also suggest that deregulation of the tissue-specific alternative splicing of fibronectin pre-mRNA is not a unique phenotype of liver cancer but rather a general feature of naturally occurring human cancer.
These results indicate that tissue-specific alternative splicing of fibronectin mRNA is modified in human liver cancer and raise a possibility that the putative molecular machinery governing alternative RNA splicing of not only fibronectin but also other cellular proteins is deregulated in malignant human tumors.
Furthermore, these results indicate a differential expression of IGF-II transcripts in nonmalignant hepatocyte proliferation (benign liver tumors and cirrhosis) as compared to liver cancer.
Thus hepatocellular cancer tissue does not over-express mRNA for hepatocyte growth factor, though this growth factor might play a role in hyperproliferative states leading to liver cancer.
As Senegal is a country where liver cancer incidence is one of the highest in the world and where people are highly exposed to aflatoxin, we screened 15 liver cancer samples from this country for mutation at codon 249 of the p53 gene.
The cyclin A gene plays an important role in both the S and G2-M phases of the cell cycle, and has been identified at a site of hepatitis B virus DNA integration in a human liver cancer.
Mutations in p53 have successfully been used to establish links between dietary aflatoxin exposure and liver cancer, exposure to ultraviolet light and skin cancer, smoking and cancers of the lung and bladder, and vinyl chloride exposure and liver cancer.
Aflatoxin may increase the proportion of p53 mutations by causing a single mutation, the codon 249 G > T transversion, thus explaining some of the excess liver cancer associated with aflatoxin exposure.
One candidate is the hepatocyte mitogen transforming growth factor alpha (TGF-alpha); in HBV-infected patients with liver cancer, TGF-alpha and HBsAg accumulate in the same hepatocytes.
To study abnormalities of the FHIT gene in human hepatocellular carcinoma (HCC), eight liver cancer cell lines, 18 matched tumorous and non-tumorous tissues from patients with HCC and three normal liver tissues were analysed by microsatellite polymorphism analysis and reverse transcription of FHIT mRNA followed by polymerase chain reaction (PCR) amplification and sequencing of the products.
The high frequency of detection of hepatitis B virus X (HBV-X) antigen in liver cells from patients with chronic hepatitis, cirrhosis, and liver cancer suggested that the expressions of HBV-X and IGF-II are associated.