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ABSTRACT: Histone deacetylation regulates chromatin remodeling and transcriptional down-regulation of specific genomic regions; it is altered in many types of cancer cells. We searched for microRNAs (miRs) that are affected by histone deacetylation and investigated the effects in hepatocellular carcinoma (HCC) cells.
HCC cell lines (HepG2, HLE, HLF, and Huh7) and immortalized liver cell lines (THLE-2 and THLE-3) were incubated with the histone deacetylase inhibitor trichostatin A. Differentially expressed messenger RNAs (mRNAs) and miRs were identified by expression profiling. Small interfering RNAs were used to reduce levels of histone deacetylases (HDAC)1-3, and HCC cell lines were transfected with miR-449. We evaluated growth of xenograft tumors from modified cells in nude mice. Cells were analyzed by immunoblot and luciferase reporter assays. We analyzed HCC samples from 23 patients.
HDAC1-3 were up-regulated in HCC samples from patients. In cell lines, inhibition of HDAC significantly increased levels of hsa-miR-449a. c-MET mRNA, which encodes the receptor tyrosine kinase for hepatocyte growth factor, is a target of miR-449. Incubation of HCC cells with trichostatin A or transfection with miR-449 reduced expression of c-MET and phosphorylation of extracellular signal-regulated kinases 1 and 2 (downstream effectors of c-MET), increased apoptosis, and reduced proliferation. Huh-7 cells transfected with miR-449 formed tumors more slowly in mice than cells expressing control miRs. HCC samples from patients had lower levels of miR-449 and higher levels of c-MET than human reference.
In HCC cells, up-regulation of HDAC1-3 reduces expression of miR-449. miR-449 binds c-MET mRNA to reduce its levels, promoting apoptosis and reducing proliferation of liver cells. Expression of miR-449 slows growth of HCC xenograft tumors in mice; this miR might function as a tumor suppressor.
Gastroenterology 05/2012; 143(3):811-20.e1-15. · 11.68 Impact Factor
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ABSTRACT: This study aimed to identify microRNAs as novel biomarkers for improved diagnosis, prognosis prediction, and as a therapeutic target for pancreatic cancer. microRNAs may have a general role by acting as superordinated key regulators of tumorigenesis.
Individual cellular molecules of multiple pathways associated with pancreatic cancer were analyzed for common microRNA binding sites, thereby enabling the identification of key regulating microRNAs. The potential of the identified microRNAs was subsequently determined in cell culture experiments.
Using bioinformatic pathway analyses, miR-548d was identified to target multiple components of pancreatic cancer-related pathways. The effect of microRNA on pancreatic cells was determined by overexpression studies using PANC-1 cells, resulting in impaired cell proliferation because of increased apoptosis and cell cycle arrest. In addition, miR-548d overexpression led to a sensitization to gemcitabine.
MicroRNA miR-548d was identified as a potential superior regulator for the development and progression of pancreatic cancer by targeting multiple factors of crucial pathways. Therapeutically, microRNAs with superordinate function, such as miR-548d, may be promising diagnostic and therapeutic tools for the future treatment of pancreatic cancer.
Pancreas 09/2011; 41(2):218-21. · 2.39 Impact Factor
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ABSTRACT: Array-based comparative genomic hybridization (array-CGH) is an emerging high-resolution and high-throughput molecular genetic technique that allows genome-wide screening for chromosome alterations. DNA copy number alterations (CNAs) are a hallmark of somatic mutations in tumor genomes and congenital abnormalities that lead to diseases such as mental retardation. However, accurate identification of amplified or deleted regions requires a sequence of different computational analysis steps of the microarray data.
We have developed a user-friendly and versatile tool for the normalization, visualization, breakpoint detection, and comparative analysis of array-CGH data which allows the accurate and sensitive detection of CNAs.
The implemented option for the determination of minimal altered regions (MARs) from a series of tumor samples is a step forward in the identification of new tumor suppressor genes or oncogenes.
Comparative and Functional Genomics 02/2009; · 1.28 Impact Factor
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ABSTRACT: Dedifferentiation of hepatocellular carcinoma implies aggressive clinical behavior and is associated with an increasing number of genomic alterations, eg deletion of 13q. Genes directly or indirectly deregulated due to these genomic alterations are mainly unknown. Therefore this study compares array comparative genomic hybridization and whole genome gene expression data of 23 well, moderately, or poorly dedifferentiated hepatocellular carcinoma, using unsupervised hierarchical clustering. Dedifferentiated carcinoma clearly branched off from well and moderately differentiated carcinoma (P<0.001 chi(2)-test). Within the dedifferentiated group, 827 genes were upregulated and 33 genes were downregulated. Significance analysis of microarrays for hepatocellular carcinoma with and without deletion of 13q did not display deregulation of any gene located in the deleted region. However, 531 significantly upregulated genes were identified in these cases. A total of 6 genes (BIC, CPNE1, RBPMS, RFC4, RPSA, TOP2A) were among the 20 most significantly upregulated genes both in dedifferentiated carcinoma and in carcinoma with loss of 13q. These genes are involved in cell-cycle control and proliferation. Of 33 downregulated genes in the dedifferentiated subgroup, 4 metallothioneins had the lowest fold change, most probably mediated through inactivation of C/EBPalpha by the PI3K/AKT cascade. In conclusion dedifferentiation of hepatocellular carcinoma is associated with upregulation of genes involved in cell-cycle control and proliferation. Notably, a significant portion of these genes is also upregulated in carcinoma with deletion of 13q. As no downregulated genes were identified and microRNAs (mir-621, mir-16-1, mir-15a) are located within the deleted region of 13q and may be lost, we speculate that these miRNAs may induce the upregulation of critical cell-cycle control genes.
Modern Pathology 10/2008; 21(12):1479-89. · 4.79 Impact Factor
