Met-thodology

New technological developments have frequently preceded major advances in biomedical research and medicine [1]. For example, the development of fluorescent DNA sequencing techniques made it possible to establish the large-scale high-throughput technology needed for human genome sequencing. Polymerase chain reaction (PCR), fluorescent DNA sequencing, and other techniques have enabled the discovery of about 1700 mendelian disease genes [2]. The advent of the DNA microarray based technologies has now made it possible to measure simultaneously the expression of tens of thousands of genes in different tissues under a variety of conditions. This high-throughput technology has afforded biomedical scientists a unique opportunity to integrate the descriptive characteristics (i.e. ‘phenotype’) of a biological system under study with the genomic readout (i.e. gene expression). The opportunity to contemplate the integrated view of biological systems has provoked a shift in biological sciences away from the classical reductionism to systems biology [1,3,4]. The systems approach to a disease is based on the hypothesis that disease processes perturb a regulatory network of genes and proteins in a way that differs from the respective normal counterpart. Consequently, by using multi-parametric measurements it may be possible to transform current diagnostic and therapeutic approaches and enable a predictive and preventive personalized medicine [4]. The application of microarray technologies to characterize tumors at the gene expression level has significantly impacted clinical oncology [5,6]. Global gene expression analysis of various human tumors has resulted in

Liver cancer: Approaching a personalized care

Transcriptional regulators in hepatocarcinogenesis – Key integrators of malignant transformation

Genome-scale profiling of gene expression in hepatocellular carcinoma: Classification, survival prediction, and identification of therapeutic targets

Notch signaling and new therapeutic options in liver disease

The immunobiology of hepatocellular carcinoma in humans and mice: Basic concepts and therapeutic implications

The biological aggressiveness of hepatocellular carcinoma (HCC) and the lack of optimal therapeutic strategies have rendered the disease a major challenge. Highly heterogeneous genetic alteration profiles of HCC have made it difficult to identify effective tailor-made molecular therapeutic targets. Therefore, classification of HCC into genetically homogeneous subclasses would be of great worth to develop novel therapeutic strategies. We clarified genome-scale chromosomal copy number alteration profiles and mutational statuses of p53 and beta-catenin in 87 HCC tumors. We investigated the possibility that HCC might be classifiable into a number of homogeneous subclasses based solely on their genetic alteration profiles. We also explored putative molecular therapeutic targets specific for each HCC subgroup. Unsupervised hierarchical cluster analysis based on chromosomal alteration profiles suggested that HCCs with heterogeneous genetic backgrounds are divisible into homogeneous subclasses that are highly associated with a range of clinicopathologic features of the tumors and moreover with clinical outcomes of the patients (P < .05). These genetically homogeneous subclasses could be characterized distinctively by pathognomonic chromosomal amplifications (eg, c-Myc-induced HCC, 6p/1q-amplified HCC, and 17q-amplified HCC). An in vitro experiment raised a possibility that Rapamycin would significantly inhibit the proliferative activities of HCCs with 17q amplification. HCC is composed of several genetically homogeneous subclasses, each of which harbors characteristic genetic alterations that can be putative tailor-made molecular therapeutic targets for HCCs with specific genetic backgrounds. Our results offer an opportunity for developing novel individualized therapeutic modalities for distinctive genome types of HCC.

Hepatitis B Virus X Protein and Pin1 in Liver Cancer: “Les Liaisons Dangereuses”

miR-122 acts as a tumor suppressor in hepatocarcinogenesis in vivo

Treatment for Hepatocellular Carcinoma in South Asia

Hepatocellular carcinoma (HCC) is the fifth most prevalent cancer worldwide and the third most lethal. Dysregulation of alternative splicing underlies a number of human diseases, yet its contribution to liver cancer has not been explored fully. The Krüppel-like factor 6 (KLF6) gene is a zinc finger transcription factor that inhibits cellular growth in part by transcriptional activation of p21. KLF6 function is abrogated in human cancers owing to increased alternative splicing that yields a dominant-negative isoform, KLF6 splice variant 1 (SV1), which antagonizes full-length KLF6-mediated growth suppression. The molecular basis for stimulation of KLF6 splicing is unknown. In human HCC samples and cell lines, we functionally link oncogenic Ras signaling to increased alternative splicing of KLF6 through signaling by phosphatidylinositol-3 kinase and Akt, mediated by the splice regulatory protein ASF/SF2. In 67 human HCCs, there is a significant correlation between activated Ras signaling and increased KLF6 alternative splicing. In cultured cells, Ras signaling increases the expression of KLF6 SV1, relative to full-length KLF6, thereby enhancing proliferation. Abrogation of oncogenic Ras signaling by small interfering RNA (siRNA) or a farnesyl-transferase inhibitor decreases KLF6 SV1 and suppresses growth. Growth inhibition by farnesyl-transferase inhibitor in transformed cell lines is overcome by ectopic expression of KLF6 SV1. Down-regulation of the splice factor ASF/SF2 by siRNA increases KLF6 SV1 messenger RNA levels. KLF6 alternative splicing is not coupled to its transcriptional regulation. Our findings expand the role of Ras in human HCC by identifying a novel mechanism of tumor-suppressor inactivation through increased alternative splicing mediated by an oncogenic signaling cascade.

Notch signaling is a complex, highly conserved mechanism, originally discovered as critical regulator of cell fate determination during development in several tissues and organs.1,2 Activation of Notch may stimulate cells either to undergo a phenotypic switch or to maintain the original cell phenotype by preventing further differentiation,3 Notch is also involved in establishing organ-specific stem cell niches necessary for epithelial tissue homeostasis.3,4 The Notch system encompasses 4 genes encoding for different membrane receptors (Notch 1, 2, 3, and 4), which are activated by their binding to 5 ligands (Jagged-1, Jagged-2, and Delta-like 1, 3, and 4).4 Cell-to-cell contact is a prerequisite for the activation of Notch signaling.3,4 Whereas Notch receptors are expressed by the “receiver” cell, ligands are expressed by the “transmitter” cell. This interaction leads to the proteolytic cleavage and subsequent nuclear translocation of the intracellular domain of Notch receptors (NICD). Once migrated into the nucleus, NICD associates with the nuclear protein of the RBP-Jκ family and transcriptionally activates several other transcriptional activators or repressors that act as critical regulators of cell differentiation, apoptosis, and proliferation4 (see drawing on the left side of Figure 1). NICD is then rapidly deactivated by phosphorylation and by proteosomal degradation. The signal is maintained through ligand-induced proteolytic supply of new NICD.

Transforming growth factor beta (TGF-beta) and related growth factors are essential regulators of embryogenesis and tissue homeostasis. The signaling pathways mediated by their receptors and Smad proteins are precisely modulated by various means. Xenopus BAMBI (bone morphogenic protein (BMP) and activin membrane-bound inhibitor) has been shown to function as a general negative regulator of TGF-beta/BMP/activin signaling. Here, we provide evidence that human BAMBI (hBAMBI), like its Xenopus homolog, inhibits TGF-beta- and BMP-mediated transcriptional responses as well as TGF-beta-induced R-Smad phosphorylation and cell growth arrest, whereas knockdown of endogenous BAMBI enhances the TGF-beta-induced reporter expression. Mechanistically, in addition to interfering with the complex formation between the type I and type II receptors, hBAMBI cooperates with Smad7 to inhibit TGF-beta signaling. hBAMBI forms a ternary complex with Smad7 and the TGF-beta type I receptor ALK5/TbetaRI and inhibits the interaction between ALK5/TbetaRI and Smad3, thus impairing Smad3 activation. These findings provide a novel insight to understand the molecular mechanism underlying the inhibitory effect of BAMBI on TGF-beta signaling.

Chemoembolization and Radioembolization for Hepatocellular Carcinoma

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