Clinicopathological significance of loss of heterozygosity on chromosome 13q in hepatocellular carcinoma.

PURPOSE: Allelic loss is the most frequently genetic alteration found in hepatocellular carcinoma (HCC). Previous genome-wide studies have indicated that chromosome 13q is one of the most frequently affected chromosomes. However, reports on detailed deletion mapping as well as detailed clinicopathological correlation are scanty. EXPERIMENTAL DESIGN: We performed high-density allelotyping on chromosome 13q in HCC from 60 patients and investigated the correlation between allelic losses on chromosome 13q and the clinicopathological features. RESULTS: Allelic loss at one or more of the 29 microsatellite markers was found in 28 (47%) of the 60 HCCs. Allelic losses were more frequently found in tumors with larger size or in tumors at more advanced tumor stages (P = 0.015 and 0.012, respectively). These two clinicopathological features were also significantly associated with the accumulation of allelic losses in terms of fractional allelic loss index (P = 0.028 and 0.018, respectively). In addition, subchromosomal regions located at 13q12.3-14.1 and 13q32 were found to be significantly associated with advanced tumor stages and larger tumor size, respectively (P = 0.008 and 0.007). CONCLUSIONS: The overall findings suggested that allelic losses on 13q might play an important role in contributing to a more aggressive tumor behavior. Putative tumor suppressor genes might be harbored at 13q12.3-14.1 and 13q32, and inactivation of these genes via allelic losses might enhance tumor progression in HCC.

Doxorubicin-induced apoptosis and chemosensitivity in hepatoma cell lines.

PURPOSE: Doxorubicin (DOX) is a commonly used anticancer drug which causes DNA damage and kills cancer cells mainly by apoptosis. However, the process leading to killing of cancer cells and the molecular basis of resistance to DOX are not well understood. To evaluate the role of p53 and the cellular effects of DOX on hepatoma cell lines, we examined three hepatoma cell lines with different p53 status--Huh-7 (mutated p53), HepG2 (wild-type p53) and Hep3B (deleted p53). METHODS: The chemosensitivity of the three hepatoma cell lines was assessed using the MTT assay, and cell cycle distribution was evaluated by flow cytometry. Western blotting and immunostaining were employed to examine the protein alterations in response to DOX treatment, and a DNA fragmentation assay was performed to detect apoptosis. RESULTS: Of the three cell lines, HepG2 was found to be most resistant to DOX, followed by Hep3B, and Huh-7 was most sensitive to DOX treatment. HepG2 showed G1 arrest 24 h after drug administration and upregulation of p53 protein level in a time-dependent manner. In Hep3B cells (deleted p53), G2/M phase arrest was observed soon after drug administration, accompanied by induced apoptosis that was p53-independent. In Huh-7 cells (mutated p53), which were most sensitive to DOX, there was neither G1 nor G2 arrest, and the level of p53 mutated protein was downregulated after DOX treatment. MDM2 and p27 proteins were downregulated in all cell lines independently of p53 status. p21 was upregulated following p53 activation at low doses of DOX in HepG2 cells, but at higher doses, p21 was downregulated in Huh-7 and HepG2 cells. CONCLUSION: DOX confers different chemosensitivity on different hepatoma cell lines with different p53 status. The contrasting relationships between chemosensitivity and p53 status and expression suggest that DOX-induced apoptosis and cell death involve pathways that are independent of p53.