Comprehensive analysis of microRNA expression patterns in hepatocellular carcinoma and non-tumorous tissues

Cyclin G1 is a target of miR-122a, a microRNA frequently down-regulated in human hepatocellular carcinoma

We investigated the role of microRNAs (miRNAs) in the pathogenesis of human hepatocellular carcinoma (HCC). A genome-wide miRNA microarray was used to identify differentially expressed miRNAs in HCCs arisen on cirrhotic livers. Thirty-five miRNAs were identified. Several of these miRNAs were previously found deregulated in other human cancers, such as members of the let-7 family, mir-221, and mir-145. In addition, the hepato-specific miR-122a was found down-regulated in approximately 70% of HCCs and in all HCC-derived cell lines. Microarray data for let-7a, mir-221, and mir-122a were validated by Northern blot and real-time PCR analysis. Understanding the contribution of deregulated miRNAs to cancer requires the identification of gene targets. Here, we show that miR-122a can modulate cyclin G1 expression in HCC-derived cell lines and an inverse correlation between miR-122a and cyclin G1 expression exists in primary liver carcinomas. These results indicate that cyclin G1 is a target of miR-122a and expand our knowledge of the molecular alterations involved in HCC pathogenesis and of the role of miRNAs in human cancer.

MicroRNA Expression Profiling in Prostate Cancer

MicroRNAs (miRNA) are small, endogenously expressed noncoding RNAs that negatively regulate expression of protein-coding genes at the translational level. Accumulating evidence, such as aberrant expression of miRNAs, suggests that they are involved in the development of cancer. They have been identified in various tumor types, showing that different sets of miRNAs are usually deregulated in different cancers. To identify the miRNA signature specific for prostate cancer, miRNA expression profiling of 6 prostate cancer cell lines, 9 prostate cancer xenografts samples, 4 benign prostatic hyperplasia (BPH), and 9 prostate carcinoma samples was carried out by using an oligonucleotide array hybridization method. Differential expression of 51 individual miRNAs between benign tumors and carcinoma tumors was detected, 37 of them showing down-regulation and 14 up-regulation in carcinoma samples, thus identifying those miRNAs that could be significant in prostate cancer development and/or growth. There was a significant trend (P=0.029) between the expression of miRNAs and miRNA locus copy number determined by array comparative genomic hybridization, indicating that genetic aberrations may target miRNAs. Hierarchical clustering of the tumor samples by their miRNA expression accurately separated the carcinomas from the BPH samples and also further classified the carcinoma tumors according to their androgen dependence (hormone naive versus hormone refractory), indicating the potential of miRNAs as a novel diagnostic and prognostic tool for prostate cancer.

Unique MicroRNA signature and clinical outcome of cancers

MicroRNAs (miRNAs) are endogenous small non-protein-coding RNAs (18-25 nucleotides) that conduct the post-transcriptional repression of hundreds of their target proteins. They regulate many kinds of basic cellular processes including proliferation, differentiation, stress response, and cell death. Recent evidence has shown that deregulation of miRNAs correlates with certain features of diverse cancers (such as tumorigenesis, differentiation status, and outcome of tumor patients), and indicates that miRNAs can act as oncogenes or tumor suppressors. Here, we summarize these recent studies and provide a new perspective on understanding the role of miRNAs in initiation and progression of cancers. We also discuss the future applications of miRNAs in diagnostic and prognostic implications of cancers.

A polymorphism of microRNA 27a genome region is associated with the development of gastric mucosal atrophy in Japanese male subjects

Noncoding microRNAs regulate the expression of various mRNAs. We attempted to clarify the relationship between miR-27a genome polymorphism and chronic gastritis. The study was performed in 179 patients with no evidence of gastric malignancy. The severity of histologic chronic gastritis was classified according to the updated Sydney system. The frequency of miR-27a G allele was 34.6%. Although the frequencies of miR-27a G allele were increased in subjects with peptic ulcer or severe mucosal atrophy, no significant differences were seen. The miR-27a polymorphism showed an interaction with gender in relation to gastric mucosal atrophy (P=.090). In only male subjects, the miR-27a polymorphism was associated with the gastric mucosal atrophy (P=.039) and both atrophy and metaplasia scores in G/G group were significantly higher than those in the other groups. The miR-27a genome region polymorphism may be an important definitive factor to develop the gastric mucosal atrophy in Japanese male subjects.

MicroRNAs and regenerative medicine

MicroRNAs, identified only relatively recently, are regulators of gene expression with potential medical benefits. The combination of microRNAs and regenerative medicine is an emerging interdisciplinary medical field that can yield exciting new possibilities for clinical medicine. In this paper, we review the prospects of microRNAs as future therapies in regenerative medicine. Recently, researchers have demonstrated the crucial roles of microRNAs, not only in the differentiation and proliferation of stem cells, which have a key function in the regeneration and transplantation of organs, but also in oncogenesis. Several lines of indirect evidence show that the initiation and maintenance of cancer stem cells might also be under the control of microRNAs. Further, microRNAs have been indicated to be involved in diverse biological processes, suggesting the potential role of these molecules in the treatment of diseases.

miR-221 and miR-222 expression affects the proliferation potential of human prostate carcinoma cell lines by targeting p27Kip1

MicroRNAs are short regulatory RNAs that negatively modulate protein expression at a post-transcriptional level and are deeply involved in the pathogenesis of several types of cancers. Here we show that miR-221 and miR-222, encoded in tandem on chromosome X, are overexpressed in the PC3 cellular model of aggressive prostate carcinoma, as compared with LNCaP and 22Rv1 cell line models of slowly growing carcinomas. In all cell lines tested, we show an inverse relationship between the expression of miR-221 and miR-222 and the cell cycle inhibitor p27(Kip1). We recognize two target sites for the microRNAs in the 3' untranslated region of p27 mRNA, and we show that miR-221/222 ectopic overexpression directly results in p27 down-regulation in LNCaP cells. In those cells, we demonstrate that the ectopic overexpression of miR-221/222 strongly affects their growth potential by inducing a G(1) to S shift in the cell cycle and is sufficient to induce a powerful enhancement of their colony-forming potential in soft agar. Consistently, miR-221 and miR-222 knock-down through antisense LNA oligonucleotides increases p27(Kip1) in PC3 cells and strongly reduces their clonogenicity in vitro. Our results suggest that miR-221/222 can be regarded as a new family of oncogenes, directly targeting the tumor suppressor p27(Kip1), and that their overexpression might be one of the factors contributing to the oncogenesis and progression of prostate carcinoma through p27(Kip1) down-regulation.

MicroRNAs in the search for understanding human diseases

MiroRNAs (miRNAs) are double-stranded, noncoding RNA molecules (with an average size of 22bp) that serve as post-transcriptional regulators of gene expression in higher eukaryotes. miRNAs play an important role in development and other cellular processes by hybridizing with complementary target mRNA transcripts, preventing their translation and thereby destabilizing the target transcripts. Though hundreds of miRNAs have been discovered in a variety of organisms, little is known about their cellular function. They have been implicated in the regulation of developmental timing and pattern formation, restriction of differentiation potential, regulation of insulin secretion, resistance to viral infection, and in genomic rearrangements associated with carcinogenesis or other genetic disorders, such as fragile X syndrome. Recent evidence suggests that the number of unique miRNA genes in humans exceeds 1000, and may be as high as 20,000. It is estimated that 20-30% of all human mRNAs are miRNA targets. During the last few years, special attention has been given to miRNAs as candidate drug targets for cancer, diabetes mellitus, obesity, and viral diseases.

The role of microRNAs in cancer: no small matter

MicroRNAs are a recently discovered class of small, evolutionarily conserved, RNA molecules that negatively regulate gene expression at the post-transcriptional level. Mature microRNAs of approximately 20-22 nucleotides are formed from longer primary transcripts by two sequential processing steps mediated by a nuclear (Drosha) and a cytoplasmic (Dicer) RNAse III endonuclease. In the context of a protein complex, the RNA-induced silencing complex (RISC), microRNAs base-pair with target messenger RNA sequences causing translational repression and/or messenger RNA degradation. MicroRNAs have been implicated in the control of many fundamental cellular and physiological processes such as tissue development, cellular differentiation and proliferation, metabolic and signalling pathways, apoptosis and stem cell maintenance. Mounting evidence indicates that microRNAs also play a significant role in cellular transformation and carcinogenesis acting either as oncogenes or tumour suppressors. This review briefly introduces microRNAs in a historical perspective and focuses on the biogenesis of microRNAs, their mode of action, mammalian microRNA functions with emphasis on their involvement in disease - particularly cancer - and their potential therapeutic use.

MicroRNAs as Cancer Players: Potential Clinical and Biological Effects

MicroRNAs (miRNAs) are nonprotein-coding RNAs that function as posttranscriptional gene regulators. They can regulate their targets directly by mRNA cleavage or by repressing their translation, depending on the degree of complementariety between the miRNA and the target. Recent evidences have shown that miRNA control cell growth, apoptosis, and differentiation. Moreover, miRNA expression correlates with cancers and could have a crucial function in tumor progression. Bioinformatic data indicates that each miRNA can control hundreds of target genes, but identification of the accurate miRNA targets will be crucial to exploit the emerging knowledge of miRNA contribution to cancer process. While the miRNA field is still emerging, the benefit of our understanding of miRNA in cancer is potentially enormous, especially if we are able to apply this knowledge to provide new therapies for patients.

Use of miRNA expression profiling to identify novel biomarkers

Micro (mi)RNAs are small, noncoding RNAs that regulate gene expression through binding to the 3´-untranslated region of mRNAs by complementary base pairing and mainly act through cleavage or translational inhibition of mRNAs. Recent studies have shown the roles of miRNAs in development and cancer, revealing the physiological and pathological importance of these tiny molecules. Therefore, as with mRNAs, researchers have focused on the global analyses of miRNAs to seek their potential use as biomarkers for physiological and pathological states of a cell. Methods developed for miRNA profiling are briefly discussed in this review. Recent evidences supporting the use of miRNAs as biomarkers in both differentiation and cancer are presented. The profiling studies may highlight the clinical relevance of miRNAs and will enable the researchers to uncover the enormous potential of these tiny molecules. In the near future, selected miRNA genes based on expression abnormalities will be tested as candidates for miRNA-based cancer gene therapy.

Characterization of microRNA expression levels and their biological correlates in human cancer cell lines

MicroRNAs are small noncoding RNAs that function by regulating target gene expression posttranscriptionally. They play a critical role in developmental and physiologic processes and are implicated in the pathogenesis of several human diseases including cancer. We examined the expression profiles of 241 human microRNAs in normal tissues and the NCI-60 panel of human tumor-derived cell lines. To quantify microRNA expression, we employed a highly sensitive technique that uses stem-loop primers for reverse transcription followed by real-time PCR. Most microRNAs were expressed at lower levels in tumor-derived cell lines compared with the corresponding normal tissue. Agglomerative hierarchical clustering analysis of microRNA expression revealed four groups among the NCI-60 cell lines consisting of hematologic, colon, central nervous system, and melanoma tumor-derived cell lines clustered in a manner that reflected their tissue of origin. We identified specific subsets of microRNAs that provide candidate molecular signatures characteristic of the tumor-derived cell lines belonging to these four clusters. We also identified specific microRNA expression patterns that correlated with the proliferation indices of the NCI-60 cell lines, and we developed evidence for the identification of specific microRNAs as candidate oncogenes and tumor suppressor genes in different tumor types. Our results provide evidence that microRNA expression patterns may mark specific biological characteristics of tumors and/or mediate biological activities important for the pathobiology of malignant tumors. These findings call attention to the potential of microRNAs to provide etiologic insights as well as to serve as both diagnostic markers and therapeutic targets for many different tumor types.

MicroRNA profiles and initiation, diagnosis and treatment of cancers in digestive organs

MicroRNA (miRNA) is a kind of small non-coding RNA containin 21 to 23 nucleotides in length that down-regulates gene expression during various crucial cell processes such as development, proliferation, differentiation and apoptosis. Recent studies supported an important role of miRNA in the initiation and progression of human malignancies. Some miRNAs may function as oncogenes or tumor suppressors. It is found that several miRNAs are directly involved in human cancers of digestive organs, including liver, colon, stomach, pancreas and bile duct. In addition, miRNA expression profiling of tumors in digestive organs has identified signatures associated with diagnosis, staging, progression, prognosis and response to treatment. Profiling has also been exploited to identify miRNA genes that might represent downstream targets of activated oncogenic pathways, or target protein coding genes involved in cancer. Moveover, miRNA-mediated therapy may be a powerful tool for cancer prevention and therapy.

Effect of BRAFV600E mutation on transcription and post-transcriptional regulation in a papillary thyroid carcinoma model

Background

microRNAs (miRNAs) are a group of non-coding single stranded RNAs measuring approximately 22 nucleotides in length that have been found to control cell growth, differentiation and apoptosis. They negatively regulate target genes and have recently been implicated in tumourigenesis. Furthermore, miRNA expression profiling correlates with various cancers, with these genes thought to act as both tumour suppressors and oncogenes. Recently, a point mutation in the BRAF gene leading to a V600E substitution has been identified as the most common genetic change in papillary thyroid carcinoma (PTC) occurring in 29–69% of cases. This mutation leads to aberrant MAPK activation that is implicated in tumourigenesis.

Aim

The aim of this study was to identify the effect that BRAF oncogene has on post-transcriptional regulation in PTC by using microRNA analysis.

Results

A unique miRNA expression signature differentiated between PTC cell lines with BRAF mutations and a normal thyroid cell line. 15 miRNAs were found to be upregulated and 23 miRNAs were downregulated. Several of these up/down regulated miRNAs may be involved in PTC pathogenesis. miRNA profiling will assist in the elucidation of disease pathogenesis and identification biomarkers and targets.

MicroRNAs and cancer

BACKGROUND

MicroRNAs (miRNAs) are small sequences of RNA, 21 to 22 nucleotides long, that have been discovered recently. They are produced from areas of the human genome that were previously thought to have no function. These sequences now appear to be important in the regulation of many fundamental processes. Evidence has recently emerged that deregulated miRNA activity is associated with human cancers.

METHODS

The English literature was searched using PubMed for publications relevant to miRNAs and cancer. Relevant references from identified publications were also sourced. These publications were reviewed to identify existing evidence for the role of miRNAs in cancer.

RESULTS

miRNAs inhibit the translation of mRNA from many target genes involved in cancer development. This leads to changes in the levels of protein encoded by these target genes and drives the development of cancer. The genes that produce miRNAs are frequently located in regions of the genome that are either lost, or amplified, in cancer cells.

CONCLUSION

Determination of the miRNA expression profile in cancer tissues should lead to a better understanding of the genetic pathways involved in tumour development.

Induction of microRNAome deregulation in rat liver by long-term tamoxifen exposure

Micro RNAs (miRNAs) are small non-coding RNA molecules that function as negative regulators of gene expression. They play a crucial role in the regulation of genes involved in the control of development, cell proliferation, apoptosis, and stress response. Although miRNA levels are substantially altered in tumors, their role in carcinogenesis, specifically at the early pre-cancerous stages, has not been established. Here we report that exposure of Fisher 344 rats to tamoxifen, a potent hepatocarcinogen in rats, for 24 weeks leads to substantial changes in the expression of miRNA genes in the liver. We noted a significant up-regulation of known oncogenic miRNAs, such as the 17-92 cluster, miR-106a, and miR-34. Furthermore, we confirmed the corresponding changes in the expression of proteins targeted by these miRNAs, which include important cell cycle regulators, chromatin modifiers, and expression regulators implicated in carcinogenesis. All these miRNA changes correspond to previously reported alterations in full-fledged tumors, including hepatocellular carcinomas. Thus, our findings indicate that miRNA changes occur prior to tumor formation and are not merely a consequence of a transformed state.

Microarray Analysis of miRNA Gene Expression

MicroRNAs (miRNAs) are small, noncoding RNAs that regulate the expression of target mRNAs. Although thousands of miRNAs have been identified, few have been functionally linked to specific biological pathways. Microarray-based expression analysis is an ideal strategy for identifying candidate miRNAs that correlate with biological pathways and for generating molecular signatures of disease states. This chapter will describe a simple, low-cost microarray platform optimized for miRNA expression analysis.

Molecular therapy in the microRNA era

MicroRNAs (miRNAs) consist of a growing class of non-coding RNAs (ncRNAs) that negatively regulate the expression of genes involved in development, differentiation, proliferation, apoptosis and other important cellular processes. miRNAs are usually 18-25 nt long and are each able to regulate several mRNAs by mechanisms such as incomplete base pairing and Post-Transcriptional Gene Silencing (PTGS). A growing number of reports have shown that aberrant miRNA expression is a common feature of human diseases including cancer, which has sparked interest in targeting these regulators of gene expression as a means of ameliorating these diseases. Here, we review important aspects of miRNA function in normal and pathological states and discuss new modalities of epigenetic intervention strategies that could be used to amend defects in miRNA/mRNA interactions.

Hepatitis B virus integration, fragile sites, and hepatocarcinogenesis

Chronic liver disease associated with long term hepatitis B virus (HBV) infection contributes importantly to the development of hepatocellular carcinoma (HCC). A salient feature of these chronic infections is the integration of subgenomic HBV DNA fragments into many different locations within the host DNA, suggesting that integration is random. Although this may promote genetic instability during liver regeneration which accompanies a bout of chronic liver disease, the actual role of integrated HBV DNA in hepatocarcinogenesis is uncertain. Importantly, most integration events retain the HBV open reading frame encoding the HBx antigen (HBxAg), which is the virus contribution to HCC. In addition, many integration events reported in the literature occur near or within fragile sites or other cancer associated regions of the human genome that are prone to instability in tumor development and progression. Genetic instability associated with integration potentially alters the expression of oncogenes, tumor suppressor genes, and microRNAs (miRNAs) that may contribute importantly to tumorigenesis. If so, then selected integration events may alter pathways that are rate limiting in hepatocarcinogenesis, thereby providing targets with diagnostic/prognostic potential and for therapeutic intervention.

Cancer research with non-coding RNA

Cancer research is not limited to medical research; it expands over several disciplines, incorporating molecular bioscience at both the macro and micro levels. All stages and aspects of cells, from development and differentiation, apoptosis, cell adhesion and many more, are research fields with a connection to cancer. Cancer research in itself is the research of cancer cures. Recently, not only cancer but also bioscience research has surfed on the new wave of RNA knowledge. Most of those RNAs are non-protein-coding RNAs and are connected to cell development and differentiation, and thereby with cancer differentiation and treatment. Here we would like to introduce the latest in cancer research that has emerged from the field of molecular biology research.

MicroRNA signatures in human cancers

MicroRNA (miRNA) alterations are involved in the initiation and progression of human cancer. The causes of the widespread differential expression of miRNA genes in malignant compared with normal cells can be explained by the location of these genes in cancer-associated genomic regions, by epigenetic mechanisms and by alterations in the miRNA processing machinery. MiRNA-expression profiling of human tumours has identified signatures associated with diagnosis, staging, progression, prognosis and response to treatment. In addition, profiling has been exploited to identify miRNA genes that might represent downstream targets of activated oncogenic pathways, or that target protein-coding genes involved in cancer.

MicroRNAs and chromosomal abnormalities in cancer cells

Over the past five decades, a plethora of nonrandom chromosomal abnormalities have been consistently reported in malignant cells facilitating the identification of cancer-associated protein coding oncogenes and tumor suppressors. The genetic dissection of hot spots for chromosomal abnormalities in the age of the sequenced human genome resulted in the discovery that microRNA (miRNA) genes, encoding for a class of small noncoding RNAs, frequently resides in such genomic regions. The combination of nonrandom chromosomal abnormalities and other types of genetic alterations or epigenetic events contribute to downregulation or overexpression of miRNAs. The consequent abnormal expression of miRNAs affect cell cycle, survival and differentiation programs and selective targeting of these noncoding genes could provide novel therapeutic options for killing the malignant cells.

MicroRNA-cancer connection: the beginning of a new tale

Cancer initiation and progression can involve microRNAs (miRNA), which are small noncoding RNAs that can regulate gene expression. Their expression profiles can be used for the classification, diagnosis, and prognosis of human malignancies. Loss or amplification of miRNA genes has been reported in a variety of cancers, and altered patterns of miRNA expression may affect cell cycle and survival programs. Germ-line and somatic mutations in miRNAs or polymorphisms in the mRNAs targeted by miRNAs may also contribute to cancer predisposition and progression. We propose that alterations in miRNA genes play a critical role in the pathophysiology of many, perhaps all, human cancers.

A limited set of human MicroRNA is deregulated in follicular thyroid carcinoma

CONTEXT

Although the pathogenesis of follicular thyroid carcinoma (FTC) and its relation to follicular adenoma (FA) remains unclear, detailed understanding of FTC carcinogenesis would facilitate addressing the scientific and clinical challenges, given that there are morphological and molecular similarities between FTC and the frequently occurring FA. Micro-RNAs (miRNAs) are a new class of small, noncoding RNAs implicated in development and cancer and may lend novel clues to FTC genesis. For the latter process, a deregulated miRNA can orchestrate the aberrant expression of several hundred target genes.

OBJECTIVE

The objective of the study was to identify deregulated miRNAs in FTC.

DESIGN

We used two high-density expression arrays to identify miRNAs and their target genes that are differentially expressed between FTC and FA. Validation was done by quantitative RT-PCR. We further functionally characterized the effect of deregulated miRNAs in vitro using HEK293T, FTC133, and K5 cell lines.

PATIENTS

In total, 45 primary thyroid samples (23 FTC, 20 FA, four normal control thyroid) were analyzed.

RESULTS

Two specific miRNAs, miR-197 and miR-346, were significantly overexpressed in FTC. In vitro overexpression of either miRNA induced proliferation, whereas inhibition led to growth arrest. Overexpression of miR-197 and miR-346 repressed the expression of their predicted target genes in vitro and in vivo.

CONCLUSIONS

Our observations show that miR-197 and miR-346 contribute to FTC carcinogenesis. Both miRNAs and their target genes might potentially provide for novel molecular markers and act as novel targets for treatment by interference, which could potentially normalize the deregulated profile of many downstream target genes.

microRNAs as oncogenes and tumor suppressors

microRNAs (miRNAs) are a new class of non-protein-coding, endogenous, small RNAs. They are important regulatory molecules in animals and plants. miRNA regulates gene expression by translational repression, mRNA cleavage, and mRNA decay initiated by miRNA-guided rapid deadenylation. Recent studies show that some miRNAs regulate cell proliferation and apoptosis processes that are important in cancer formation. By using multiple molecular techniques, which include Northern blot analysis, real-time PCR, miRNA microarray, up- or down-expression of specific miRNAs, it was found that several miRNAs were directly involved in human cancers, including lung, breast, brain, liver, colon cancer, and leukemia. In addition, some miRNAs may function as oncogenes or tumor suppressors. More than 50% of miRNA genes are located in cancer-associated genomic regions or in fragile sites, suggesting that miRNAs may play a more important role in the pathogenesis of a limited range of human cancers than previously thought. Overexpressed miRNAs in cancers, such as mir-17-92, may function as oncogenes and promote cancer development by negatively regulating tumor suppressor genes and/or genes that control cell differentiation or apoptosis. Underexpressed miRNAs in cancers, such as let-7, function as tumor suppressor genes and may inhibit cancers by regulating oncogenes and/or genes that control cell differentiation or apoptosis. miRNA expression profiles may become useful biomarkers for cancer diagnostics. In addition, miRNA therapy could be a powerful tool for cancer prevention and therapeutics.

Impact of RNA interference on gene networks

Small endogenous RNAs such as microRNAs (miRNAs) and small interfering RNAs (siRNAs) have been found to post-transcriptionally control cellular gene networks by targeting complementary mRNAs for translation impairment (miRNA) or destruction (siRNA). We have developed a computational model, coordinated to molecular and biochemical parameters of RNA interference pathways, to provide (semi-) quantitative insight into the molecular events managing siRNA-mediated gene expression silencing in native and synthetic gene networks. Based on mass-conservation principles and kinetic rate laws, we converted biochemical RNA interference pathways into a set of ordinary differential equations that describe the dynamics of siRNA-mediated translation-regulation in mammalian cells. Capitalizing on mechanistic details of synthetic transactivator operation, we wired this model into a transcription control circuitry in which the siRNA and its target mRNA are independently regulated at the transcriptional level. In this context, we studied the impact of siRNA transcription timing on the onset of target gene transcription and production kinetics of target mRNA-encoded proteins. We also simulated the rate of siRNA-induced mRNA depletion and demonstrated that the relative concentrations of interacting siRNAs/mRNAs and the number of siRNA-specific target sites on a transcript modulate (i) the rate of target mRNA disappearance, (ii) the steady-state mRNA levels and (iii) induction dynamics of mRNA-encoded protein production. As our model predictions are consistent with available biochemical parameters, extrapolations may improve our understanding of how complex regulatory gene networks are impacted by small endogenous RNAs.

Identification by Real-time PCR of 13 mature microRNAs differentially expressed in colorectal cancer and non-tumoral tissues

MicroRNAs (miRNAs) are short non-coding RNA molecules playing regulatory roles by repressing translation or cleaving RNA transcripts. Although the number of verified human miRNA is still expanding, only few have been functionally described. However, emerging evidences suggest the potential involvement of altered regulation of miRNA in pathogenesis of cancers and these genes are thought to function as both tumours suppressor and oncogenes. In our study, we examined by Real-Time PCR the expression of 156 mature miRNA in colorectal cancer. The analysis by several bioinformatics algorithms of colorectal tumours and adjacent non-neoplastic tissues from patients and colorectal cancer cell lines allowed identifying a group of 13 miRNA whose expression is significantly altered in this tumor. The most significantly deregulated miRNA being miR-31, miR-96, miR-133b, miR-135b, miR-145, and miR-183. In addition, the expression level of miR-31 was correlated with the stage of CRC tumor. Our results suggest that miRNA expression profile could have relevance to the biological and clinical behavior of colorectal neoplasia.

Right hepatic lobectomy in elderly patients with hepatocellular carcinoma

BACKGROUND/AIMS

The outcome of hepatectomy in elderly patients with hepatocellular carcinoma have been reported, however neither the morphological nor functional hepatic regeneration in elderly patients have been fully investigated.

MATERIALS AND METHODS

Fifty-six patients with hepatocellular carcinoma, who underwent a right hepatic lobectomy over an 8-year period, were classified into three groups according to their age; group 1 (n = 7), more than 70 years of age; group 2 (n = 40), patients from 50 to 69 years of age and group 3 (n = 9), under 50 years of age. There were no significant differences regarding backgrounds or intra-operative parameters among the three groups. The perioperative hepatic function, postoperative complications and the regeneration rate of the remnant left lobe at 1 month after operation were compared.

RESULTS

No differences were found in the regeneration rate, however, the levels of the hepaplastin test and lecithin:cholesterol acyltransferase at 7 days after hepatectomy in group 1 (31.3%, 8.8 U) were significantly lower than those in groups 2 and 3 (37.4%, 18.4 U; 47.9%, 29.4 U, respectively). The incidence of hospital death due to hepatic failure in group 1 (42.9%) was also significantly higher than that of group 2 (5.0%) or group 3 (0%).

CONCLUSION

The decline of postoperative protein synthesis regardless of the voluminal regeneration is a characteristic of the elderly. This phenomenon might thus be an important promoter of postoperative hepatic failure which remains unpredictable using any type of examination. Therefore, at this time, a major hepatectomy is not recommended as a viable treatment alternative in the elderly.