Novel human malignancy-associated gene (MAG) expressed in various tumors and in some tumor preexisting conditions.

We have identified a novel human malignancy-associated gene (MAG) expressed in various malignant tumors including glioblastomas and hepatocellular carcinomas (HCCs) and in tumor preexisting conditions such as hepatitis C virus- and hepatitis B virus-induced liver cirrhosis. The expression of MAG was characterized using reverse transcription-PCR (RT-PCR), rapid amplification of cDNA ends PCR, RNA dot blotting, RNase protection assay, and Northern blot analysis. Rapid amplification of cDNA ends PCR yielded a 536-bp MAG fragment in HCC, macroregenerative liver nodules with dysplasia, and liver cirrhosis but not in normal liver or placenta. By RT-PCR, MAG expression was not found in 12 different normal tissues but found in 46 of 51 (90%) premalignant and malignant tissues of various sites. Embryonic liver and brain were positive for MAG expression together with tumors from the same organs, but the corresponding normal adult tissues were negative. By RNase protection assay, MAG mRNA was expressed in the HepG2 liver tumor cell line and in an ovarian carcinoma but not in normal liver. The estimated transcript size from Northern blot analysis was 8.8 kb. This novel gene may play a role in the progression of premalignant conditions and in the development of HCC and other cancers.