Expression profile of nine novel genes differentially expressed in hepatitis B virus-associated hepatocellular carcinomas

Chronic hepatitis B virus (HBV) infection is known to be one of the major c auses in the development of hepatocellular carcinoma (HCC), although the bi omolecular mechanism(s) involved remain unclear. To identify the cellular g ene(s) involved in HBV-associated hepatocarcinogenesis, we used the mRNA di fferential display method and examined three paired tumor and nontumor tiss ues, all of which had chromosomally integrated HBV-DNA through chronic infe ction. Using 240 different combinations of three one-base anchored oligo-dT primers and 80 arbitrary 13-mers, genes decreased or increased in expressi on more than twofold between each tumor tissue and its paired nontumor tiss ue were identified. Twenty-nine known genes and four novel genes were diffe rentially over-expressed in the HCC tumor tissues. In contrast, 27 known ge nes and five novel genes were under-expressed in those tumor tissues. The n ucleotide sequences of the nine novel gene fragments were determined and th eir expression patterns were examined in 40 HCC samples. HA61T2, PT18, HG63 T1, and HG57T1 were preferentially over-expressed in 32 cases (80%, P<0.001 ), 24 cases (60%), 23 cases (57.5%) and 22 cases (55%) of the 40 tumor tiss ues, respectively. There was an increased frequency of HG57T1 over-expressi on in HCC patients with HBV-positive serology and low serum alpha-feto prot ein (AFP) levels (P<0.05). DNT10, PTB, PT19, ENT25 and HA6T4 were under-exp ressed in 26 cases (65%), 23 cases (57.5%), 21 cases (53%), 20 cases (50%) and 18 cases (45%) of the 40 tumor samples, respectively. There was a stron g correlation of DNT10 under-expression with high serum AFP level in HCC pa tients, irrespective of HBV serology (P<0.01). HA6T4 was preferentially und er-expressed in HCC tumors in patients with HBV-positive serology and high serum AFP levels (P<0.05). Thus, the functional analyses of the known and n ovel genes identified in this study should prove valuable to further unders tand the mechanism(s) of hepatocarcinogenesis.