Expression of genes involved with cell cycle control, cell growth and chromatin modification are altered in hepatoblastomas

Hepatoblastoma is a rare pediatric liver tumor. While much progress has been made in the treatment of the disease, very little is known about the moleculer events underlying the pathogenesis of this disease. We sought to investigate a series of hepatoblastomas for alterations in gene expression patterns with emphasis on important cell regulatory genes, including chromatin modifying enzymes, cyclin dependent kinase inhibitors, growth factors, oncogenes and cell cycle regulators. Total RNA was extracted from a series of sporadic hepatoblastomas with matched normal liver, some unmatched tumors and fetal livers, and gene expression was measured for various genes using RNase Protection Analysis (RPA). The results of this analysis show that the expression of many important regulatory genes are distinctly altered in these tumors, and a subset of tumors can be distinguished on the basis of these gene expression differences and histopathological features. Because the molecular events underlying the pathogenesis of this rare tumor are so poorly understood, this study represents a first step in determining some of the possible mechanisms involved which may provide future avenues of research.

Spectral karyotyping and chromosome banding studies of primary breast carcinomas and their lymph node metastases

Three primary breast tumors and their lymph node metastases were characterized by G-banding, spectral karyotyping (SKY), and fluorescence in situ hybridization (FISH). In each case, the karyotypic abnormalities detected were similar in the primary tumor and its matched metastasis. Two of the pairs had near-diploid karyotypes with three to four chromosomal aberrations, whereas the third pair had a near-pentaploid chromosome content and many marker chromosomes in the primary tumor and a near-tetraploid chromosome number with almost the same marker chromosomes in the metastasis. SKY and FISH confirmed the karyotypic similarities between the primary tumors and their metastases and, in addition, improved the identification and characterization of marker chromosomes. One of the tumor pairs with near-diploid karyotypes had gain of 8q, 16q, and 17q, whereas the other had gain of 1q and chromosome 8 material in the form of ring chromosomes. The third pair had more complex chromosomal translocations and numerical changes resulting in net gain of material from chromosomes X, 1, 2, 6, 7, 14, 16, 19, and 20, and chromosome arms 8q and 11q, as well as net loss of material from chromosomes 3, 13, 18, 21, and 22. The present study underscores the need to combine conventional chromosome banding and molecular cytogenetic techniques in the cytogenetic analysis of solid tumors.

Modulating IGFBP-3 expression by trichostatin A: potential therapeutic role in the treatment of hepatocellular carcinoma

The Hep3B cell line analyzed in the present study is a widely used in vitro model in studies characterizing pathogenetic, functional, and therapeutic aspects of human hepatocellular carcinoma (HCC). Here we have determined the chromosomal composition using a combination of cytogenetic techniques. In agreement with the original description for this cell line, Hep3B was found to have a hypotriploid chromosome content carrying 59-63 chromosomes and no cytogenetic differences were demonstrated between early and late passages suggesting that this cell line has remained stable after repeated subculturing. Mutations and alterations of the IGF-axis as well as of chromosome 1p34, where the genes for histone deacetylase 1 (HDAC1) and transforming growth factor beta receptor interacting protein-1 (TRIP-1) map, are frequent events in hepatocarcinogenesis. This study characterizes the Hep3B cell line in detail at the karyotypic level, using comparative genomic hybridization (CGH), spectral karyotyping (SKY), G-banding and FISH techniques. We have also examined the effects of the histone deacetylase inhibitor trichostatin A (TSA) on members of the IGF-axis, and analysed them with regard to the karyotype. The results show that expression of one member of the IGF-axis, IGFBP-3, is greatly upregulated by treatment of Hep3B cells with TSA. As IGFBP-3 has been shown to induce apoptosis, these results suggest a possible use for histone deacetylase inhibitors and/or IGFBP-3 in the treatment of HCC.