Novel mutations in transthyretin gene associated with hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is one of the major health problems with increasing incidence worldwide. We report the elevation in transthyretin (TTR) expression following HCC induction using diethylnitrosamine (DEN) and 2-aminoacetylfluorine (2-AAF) in male Wistar rats. The increase in its expression took place at very early stage and remained elevated throughout HCC progression. The analysis of TTR gene in HCC bearing rats revealed four novel mutations that alter three amino acids at positions 61, 100, and 115. While these mutations do not directly affect the binding of TTR to thyroxine (T4 ), the mutation in amino acid 115 interferes with TTR tetramer formation that leads to its accumulation. Further, the mutated TTR is unable to cleave C-terminal of apolipoprotein A1 (APOA1) that results in abnormal lipid metabolism. This has correlation with development of liver cirrhosis and HCC. Furthermore, the mutated TTR seems to have potential as biomarker for early detection of HCC.