MicroRNA-21 regulates expression of the PTEN tumor suppressor gene in human hepatocellular cancer

Tenets of PTEN tumor suppression

Since its discovery as the elusive tumor suppressor gene at the frequently mutated 10q23 locus, PTEN has been identified as lost or mutated in several sporadic and heritable tumor types. A decade of work has established that PTEN is a nonredundant phosphatase that is essential for regulating the highly oncogenic prosurvival PI3K/AKT signaling pathway. This review discusses emerging modes of PTEN function and regulation, and speculates about how manipulation of PTEN function could be used for cancer therapy.

MicroRNAs

MicroRNAs (miRNAs) are small, noncoding RNAs with regulatory functions, which play an important role in many human diseases, including cancer. An emerging number of studies show that miRNAs can act either as oncogenes or as tumor suppressor genes or sometimes as both. Germline, somatic mutations and polymorphisms can contribute to cancer predisposition. miRNA expression levels have diagnostic and prognostic implications, and their roles as anticancer therapeutic agents is promising and currently under investigation.

Differential expression of PTEN-targeting microRNAs miR-19a and miR-21 in Cowden syndrome

Germline mutations in the gene encoding phosphatase and tensin homolog deleted on chromosome ten (PTEN [MIM 601728]) are associated with a number of clinically distinct heritable cancer syndromes, including both Cowden syndrome (CS) and Bannayan-Riley-Ruvalcaba syndrome (BRRS). Seemingly identical pathogenic PTEN mutations have been observed in patients with CS and BRRS, as well as in patients with incomplete features of CS, referred to as CS-like (CSL) patients. These observations indicate that additional, unidentified, genetic and epigenetic factors act as phenotypic modifiers in these disorders. These genetic factors could also contribute to disease in patients with CS, CSL, or BRRS without identifiable PTEN mutations. Two potential modifiers are miR-19a and miR-21, which are previously identified PTEN-targeting miRNAs. We investigated the role of these miRNAs by characterizing their relative expression levels in PTEN-mutation-positive and PTEN-mutation-negative patients with CS, CSL, or BRRS. Interestingly, we observed differential expression of miR-19a and miR-21 in our PTEN-mutation-positive patients. Both were found to be significantly overexpressed within this group (p < 0.01) and were inversely correlated with germline PTEN protein levels. Similarly, the relative expression of miR-19a and miR-21 was differentially expressed in a series of PTEN-mutation-negative patients with CS or CSL with variable clinical phenotypes and decreased full-length PTEN protein expression. Among PTEN-mutation-positive patients with CS, both miRNAs were significantly overexpressed (p = 0.006-0.013). Taken together, our study results suggest that differential expression of PTEN-targeting miR-19a and miR-21 modulates the PTEN protein levels and the CS and CSL phenotypes, irrespective of the patient's mutation status, and support their roles as genetic modifiers in CS and CSL.

Research progress of the relationship between microRNAs and p53 gene in oncogenesis

The initiation and development of oncogenesis are a multi-step and complicated process, in which activation of oncogenes and inactivation of tumor suppressor genes are involved. MicroRNAs (miRNAs) are a new class of endogenous, non-coding small RNA molecules. It has been demonstrated that their expression levels are closely associated with human pathogenesis of cancers. They may participate in regulating the abnormal expression of oncogenes and tumor suppressor genes. Mutation in tumor suppressor gene p53 is the most frequent phenomenon in human cancer, and up to now, almost 50% human cancers are demonstrated associated with p53 mutation. Recent studies showed that miRNAs might play a role in regulating the tumor-suppressor activity of p53 gene. In this review, the research progress in this field is discussed.

Potential role of miR-9 and miR-223 in recurrent ovarian cancer

BACKGROUND

MicroRNAs (miRNAs) are small, noncoding RNAs that negatively regulate gene expression by binding to target mRNAs. miRNAs have not been comprehensively studied in recurrent ovarian cancer, yet an incurable disease.

RESULTS

Using real-time RT-PCR, we obtained distinct miRNA expression profiles between primary and recurrent serous papillary ovarian adenocarcinomas (n = 6) in a subset of samples previously used in a transcriptome approach. Expression levels of top dysregulated miRNA genes, miR-223 and miR-9, were examined using TaqMan PCR in independent cohorts of fresh frozen (n = 18) and FFPE serous ovarian tumours (n = 22). Concordance was observed on TaqMan analysis for miR-223 and miR-9 between the training cohort and the independent test cohorts. Target prediction analysis for the above miRNA "recurrent metastatic signature" identified genes previously validated in our transcriptome study. Common biological pathways well characterised in ovarian cancer were shared by miR-9 and miR-223 lists of predicted target genes. We provide strong evidence that miR-9 acts as a putative tumour suppressor gene in recurrent ovarian cancer. Components of the miRNA processing machinery, such as Dicer and Drosha are not responsible for miRNA deregulation in recurrent ovarian cancer, as deluded by TaqMan and immunohistochemistry.

CONCLUSION

We propose a miRNA model for the molecular pathogenesis of recurrent ovarian cancer. Some of the differentially deregulated miRNAs identified correlate with our previous transcriptome findings. Based on integrated transcriptome and miRNA analysis, miR-9 and miR-223 can be of potential importance as biomarkers in recurrent ovarian cancer.

High-dimensional biology to comprehend hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the fifth most common cancer worldwide and is the third leading cause of death from cancer. The diverse etiology, high morbidity/mortality, lack of diagnostic markers for early diagnosis and the highly variable clinical course of HCC have hindered advances in diagnosis and treatment. Microsatellite instability, chromosomal aberrations, mutations in key cell cycle genes and epigenetic changes have been reported in HCC. Availability of modern technologies advance 'high-dimensional biology' (HDB), a term that refers to the simultaneous study of the genetic variants (genome), transcription (mRNA; transcriptome), peptides and proteins (proteomics), and metabolites (metabolomics) for the intermediate products of metabolism of an organ, tissue or organism. The growing interest in omics-based research has enabled the simultaneous examination of thousands of genes, transcripts and proteins of interest, with high-throughput techniques and advanced analytical tools for data analysis. The use of each approach towards functional omics has lead to the classification of HCC into molecular subgroups. Here we review the use of HDB as a tool for the identification of markers for screening, diagnosis, molecular classification and the discovery of new therapeutic drug targets of HCC. With the extensive use of HDB, it may be possible in the near future, to have custom-made therapeutic regimens for HCC based on the molecular subtype, ultimately leading to an improved survival of HCC patients.

miR-122, a paradigm for the role of microRNAs in the liver

Recent studies have uncovered profound and unexpected roles for a family of tiny regulatory RNAs, known as microRNAs (miRNAs), in the control of diverse aspects of hepatic function and dysfunction, including hepatocyte growth, stress response, metabolism, viral infection and proliferation, gene expression, and maintenance of hepatic phenotype. In liver cancer, misexpression of specific miRNAs suggests diagnostic and prognostic significance. Here, we review the biology of the most abundant miRNA in human liver, miR-122, and consider the diversity of its roles in the liver. We provide a compilation of all miRNAs expressed in the liver, and consider some possible therapeutic opportunities for exploiting miRNAs in the different settings of liver diseases.

MicroRNA gene expression profile of hepatitis C virus-associated hepatocellular carcinoma

MicroRNAs are small noncoding RNAs that regulate gene expression by targeting messenger RNAs (mRNAs) through translational repression or RNA degradation. Many fundamental biological processes are modulated by microRNAs, and an important role for microRNAs in carcinogenesis is emerging. Because understanding the pathogenesis of viral-associated hepatocellular carcinomas is important in developing effective means of classification, prognosis, and therapy, we examined the microRNA expression profiles in a large set of 52 human primary liver tumors consisting of premalignant dysplastic liver nodules and hepatocellular carcinomas by quantitative real-time polymerase chain reaction. All patients were infected with hepatitis C, and most had liver cirrhosis. Initially, the accessibility of microRNAs from formalin-fixed paraffin-embedded archival liver tissue by real-time polymerase chain reaction assays was shown. Subsequently, target parenchyma from routinely processed tissue was macrodissected, RNA was extracted, and reverse transcription followed by quantitative real-time polymerase chain reaction was performed. Relative quantification was performed by the 2(-DeltaDeltaCt) method with normal livers as a calibrator. In order to obtain a comprehensive microRNA gene expression profile, 80 microRNAs were examined in a subset of tumors, which yielded 10 up-regulated and 19 down-regulated microRNAs compared to normal liver. Subsequently, five microRNAs (miR-122, miR-100, miR-10a, miR-198, and miR-145) were selected on the basis of the initial results and further examined in an extended tumor sample set of 43 hepatocellular carcinomas and 9 dysplastic nodules. miR-122, miR-100, and miR-10a were overexpressed whereas miR-198 and miR-145 were up to 5-fold down-regulated in hepatic tumors compared to normal liver parenchyma.

CONCLUSION

A subset of microRNAs are aberrantly expressed in primary liver tumors, serving both as putative tumor suppressors and as oncogenic regulators.

Modulation of miRNA activity in human cancer: a new paradigm for cancer gene therapy?

MicroRNAs (miRNAs) were discovered more than a decade ago as noncoding, single-stranded small RNAs (approximately 22 nucleotides) that control the timed gene expression pattern in Caenorhabditis elegans life cycle. A number of these evolutionarily conserved, endogenous miRNAs have been shown to regulate mammalian cell growth, differentiation and apoptosis. miRNAs are multispecific by nature. The individual miRNA is capable of modulating the expression of a network of mRNAs that it binds by imperfect sequence complementarity. Human cancers commonly exhibit an altered expression profile of miRNAs with oncogenic (miR-21, miR-106a and miR-155) or tumor-suppressive (let-7, miR-15a/16, miR-34a and miR-143/145) activity. As consistent with the natural function of miRNAs in specifying cellular phenotype, miRNA-based cancer gene therapy offers the theoretical appeal of targeting multiple gene networks that are controlled by a single, aberrantly expressed miRNA. Reconstitution of tumor-suppressive miRNA, or sequence-specific knockdown of oncogenic miRNAs by 'antagomirs,' has produced favorable antitumor outcomes in experimental models. We discuss pending issues that need to be resolved prior to the consideration of miRNA-based experimental cancer gene therapy. These include the need for definitive mRNA target validation, our incomplete understanding of rate-limiting cellular components that impact the efficiency of this posttranscriptional gene-silencing phenomenon, the possibility for nonspecific immune activation and the lack of a defined, optimal mode of delivery.

Breast cancer metastasis: a microRNA story

MicroRNAs (miRNAs) are small noncoding RNAs with regulatory functions, which play an important role in breast cancer. Several studies have shown that miRNAs can act either as tumor suppressors or as oncogenes, and that measurement of miRNA expression in malignancies may have diagnostic and prognostic implications. This article highlights a series of three recent studies that prove the involvement of miRNAs in breast cancer metastases. The first proves that miR-10b indirectly activates the pro-metastatic gene RHOC by suppressing HOXD10, thus leading to tumor invasion and metastasis. The second proves that miR-373 and miR-520c can also promote tumor invasion and metastasis, at least in part by regulating the gene CD44. The third identifies miR-335, miR-206, and miR-126 as suppressors of breast cancer metastasis. Loss of miR-335 leads to the activation of SOX4 and TNC (encoding tenascin C), which are responsible for the acquisition of metastatic properties. Altogether, these remarkable findings are important for our understanding of malignant transformation in the breast and may have implications for the management of patients with advanced breast cancer. The use of miRNAs as anticancer therapeutic agents is promising, and such fine molecular studies certainly help in bringing miRNAs closer to clinical practice.

Harnessing the RNA interference pathway to advance treatment and prevention of hepatocellular carcinoma

Primary liver cancer is the fifth most common malignancy in the world and is a leading cause of cancer-related mortality. Available treatment for hepatocellular carcinoma (HCC), the commonest primary liver cancer, is rarely curative and there is a need to develop therapy that is more effective. Specific and powerful gene silencing that can be achieved by activating RNA interference (RNAi) has generated enthusiasm for exploiting this pathway for HCC therapy. Many studies have been carried out with the aim of silencing HCC-related cellular oncogenes or the hepatocarcinogenic hepatitis B virus (HBV) and hepatitis C virus (HCV). Proof of principle studies have demonstrated promising results, and an early clinical trial assessing RNAi-based HBV therapy is currently in progress. Although the data augur well, there are several significant hurdles that need to be overcome before the goal of RNAi-based therapy for HCC is realized. Particularly important are the efficient and safe delivery of RNAi effecters to target malignant tissue and the limitation of unintended harmful non-specific effects.

Muscling through the microRNA world

microRNAs (miRNAs) are a class of highly conserved small non-coding RNAs that negatively regulate gene expression post-transcriptionally. The emerging field of miRNA biology has begun to unravel roles for these regulatory molecules in a range of biological functions, including cardiac and skeletal muscle development, as well as in muscle-related disease processes. In this paper, we review the role of miRNAs in muscle biology. Recent genetic studies have demonstrated that miRNAs are required for both proper muscle development and function, with crucial roles for miRNAs being identified in regulating muscle cell proliferation and differentiation. Furthermore, dysregulated expression of miRNAs has been correlated to certain muscle-related diseases, including cardiac hypertrophy, cardiac arrhythmias, and muscular dystrophy.

MicroRNA expression profiling in relation to the genetic heterogeneity of acute myeloid leukemia

Acute myeloid leukemia (AML) is a highly diverse disease characterized by various cytogenetic and molecular abnormalities. MicroRNAs are small noncoding RNAs that show variable expression during myeloid differentiation. MicroRNA expression in marrow blasts in 215 cases of newly diagnosed and (cyto)genetically defined AML was assessed using quantitative reverse-transcription-polymerase chain reaction (RT-PCR) for 260 human microRNAs. In the same series, mRNA gene expression profiles were established, allowing a direct comparison between microRNA and mRNA expression. We show that microRNA expression profiling following unsupervised analysis reveals distinctive microRNA signatures that correlate with cytogenetic and molecular subtypes of AML (ie, AMLs with t(8;21), t(15;17), inv(16), NPM1, and CEBPA mutations). Significantly differentially expressed microRNAs for genetic subtypes of AML were identified. Specific microRNAs with established oncogenic and tumor suppressor functions, such as microRNA-155, microRNA-21, and let-7, appear to be associated with particular subtypes. Combinations of selected sets of microRNAs could predict cytogenetically normal AML with mutations in the genes of NPM1 and CEBPA and FLT3-ITD with similar accuracy as mRNA probe set combinations defined by gene expression profiling. MicroRNA expression apparently bears specific relationships to the heterogeneous pathobiology of AML. Distinctive microRNA signatures appear of potential value in the clinical diagnosis of AML.

Advances in research of microRNA- and HBV-related liver cancer

MicroRNA is a kind of endogenous non-coding small RNA, is universally present in animals, plants and viruses and plays an important role in the development, proliferation, differentiation and apoptosis of organisms through complementary pairing with target mRNA, which can regulate its expression or translation. Recent studies indicate that miRNA is closely associated with tumors. Study on tumor-associated miRNA using techniques of experimental biology and bioinformatics is currently a hot subject of research. Recent studies on hepatocellular carcinoma(HCC) have shown that HCC is correlated with abnormal expression of several miRNAs, such as miRNA-122, -21, -195, -18, -199a. However, few studies on miRNA expression in HBV-infected diseases are available. This paper reviews researches on the association of microRNA with the development of liver cancer.

Dissecting microregulation of a master regulatory network

Background

The master regulator p53 tumor-suppressor protein through coordination of several downstream target genes and upstream transcription factors controls many pathways important for tumor suppression. While it has been reported that some of the p53's functions are microRNA-mediated, it is not known as to how many other microRNAs might contribute to the p53-mediated tumorigenesis.

Results

Here, we use bioinformatics-based integrative approach to identify and prioritize putative p53-regulated miRNAs, and unravel the miRNA-based microregulation of the p53 master regulatory network. Specifically, we identify putative microRNA regulators of a) transcription factors that are upstream or downstream to p53 and b) p53 interactants. The putative p53-miRs and their targets are prioritized using current knowledge of cancer biology and literature-reported cancer-miRNAs.

Conclusion

Our predicted p53-miRNA-gene networks strongly suggest that coordinated transcriptional and p53-miR mediated networks could be integral to tumorigenesis and the underlying processes and pathways.

MicroRNAs as targets for antisense-based therapeutics

MicroRNAs (miRNAs) are a novel class of endogenous non-coding single-stranded RNAs, which regulate gene expression post-transcriptionally by base pairing with their target mRNAs. So far > 5000 miRNA entries have been registered and miRNAs have been implicated in most, if not all, central cellular processes and several diseases. As the mechanism of action for miRNA regulation of target mRNAs is mediated by Watson-Crick base pairing, antisense oligonucleotides targeting the miRNAs appear as an obvious choice to specifically inhibit miRNA function. Indeed, miRNAs can be antagonized in vivo by oligonucleotides composed of high-affinity nucleotide mimics. Lessons learned from traditional antisense strategies and small-interfering RNA approaches, that is from potent nucleotide mimics, design rules, pharmacokinetics, administration and safety issues, are likely to pave the way for future clinical trials of miRNA-antagonizing oligonucleotides.

Viral hepatocarcinogenesis: from infection to cancer

Hepatocellular carcinoma (HCC) is a worldwide health issue that has started receiving attention but is still poorly understood. However, the hepatitis B virus (HBV) and the hepatitis C virus (HCV) are known to be two major causative agents of HCC. They differ in their modes of infection, their treatment options, their genomes and their carcinogenic abilities. However, both share a link with HCC through alterations of the host genome. In order to continue in our search for the mechanisms behind viral hepatocarcinogenesis, the individual entities (HBV, HCV, HCC and host), their natural history, treatment options and genomic properties must be further understood. Additionally, an understanding of the genomics, the link between the entities, is crucial for the success of the ongoing search for therapeutic options for HCC. Similar to most types of cancer, hepatocarcinogenesis is a multistep process involving different genetic alterations that ultimately lead to malignant transformation of the hepatocyte. As technology advances and research continues, the genetic changes and influences among these entities will prove essential to improved diagnostic and therapeutic options. It remains a challenge to provide a clear picture of the connection between virus and cancer. We review (i) the epidemiological link between HBV/HCV infection to HCC; (ii) prevention and control of chronic hepatitis B or C in reducing HCC risk; and (iii) genetic characters of viruses and hosts and the mechanisms associated with HCC susceptibilities, with the intention of providing a direction for future research and treatment.

Oncogenicity of DNA in vivo: tumor induction with expression plasmids for activated H-ras and c-myc

All vaccines and other biological products contain contaminating residual DNA derived from the production cell substrate. Whether this residual cell-substrate DNA can induce tumors in vaccine recipients and thus represent a risk factor has been debated for over 50 years without resolution. As a first step in resolving this issue, we have generated expression plasmids for the activated human H-ras oncogene and for the murine c-myc proto-oncogene. Their oncogenic activity was confirmed in vitro using the focus-formation transformation assay. Two strains of adult and newborn immune-competent mice were inoculated with different amounts of either plasmid alone or with a combination of the H-ras and c-myc plasmids. Tumors developed only in mice inoculated with both plasmids and only at the highest amount of DNA (12.5 microg of each plasmid). The NIH Swiss mouse was more sensitive than the C57BL/6 mouse, and newborn animals were more sensitive than adults. Cell lines were established from the tumors. PCR and Southern hybridization analyses demonstrated that both inoculated oncogenes were present in all of the tumor-derived cell lines and that the cells in the tumors were clonal. Western analysis demonstrated that both oncoproteins were expressed in these cell lines. These results demonstrate that cellular oncogenes can induce tumors following subcutaneous inoculation. Such information provides a possible way of evaluating and estimating the theoretical oncogenic risk posed by residual cell-substrate DNA in vaccines.

MicroRNAs and immunity: novel players in the regulation of normal immune function and inflammation

The discovery of microRNAs (miRNAs) is one of the major scientific breakthroughs in recent years and has revolutionized the way we look at gene regulation. Although we are still at a very early stage in understanding their impact on immunity, miRNAs are changing the way we think about the development of the immune system and regulation of immune functions. MiRNAs are implicated in establishing and maintaining the cell fate of immune cells (e.g. miR-181a and miR-223), and they are involved in innate immunity by regulating Toll-like receptor signaling and ensuing cytokine response (e.g. miR-146). Moreover, miRNAs regulate central elements of the adaptive immune response such as antigen presentation (e.g. miR-155) and T cell receptor signaling (miR-181a). Recent evidence showing altered miRNA expression in chronic inflammatory diseases (e.g. miR-203 and miR-146) suggests their involvement in immune-mediated diseases. Furthermore, miRNAs have been implicated in viral immune escape and anti-viral defense (e.g. miR-196). In this review, we will summarize the latest findings about the role of miRNAs in the development of the immune system and regulation of immune functions and inflammation.

The utility of LNA in microRNA-based cancer diagnostics and therapeutics

MicroRNAs (miRNAs) are a novel class of small endogenous non-coding RNAs that regulate gene expression post-transcriptionally by binding to their cognate target mRNAs. Emerging evidence implies that miRNAs play important roles in cancer and thus, miRNAs have rapidly emerged as valuable markers for cancer diagnostics and promising targets for therapeutics. Locked nucleic acid (LNA) is a conformational RNA analoque that binds complementary RNA with unprecedented affinity and specificity. These properties make LNA well suited for miRNA detection and analysis for cancer diagnostics. Furthermore, recent studies on LNA-mediated silencing of miRNA function in vitro and in vivo support the potential of LNA in therapeutic intervention of cancer-associated miRNAs.

Advances in microRNAs: implications for gene therapists

MicroRNAs (miRNAs) are a class of small regulatory RNAs that are thought to regulate the expression of as many as one-third of all human messenger RNAs (mRNAs). miRNAs are thought to be involved in diverse biological processes, including tumorigenesis. Analysis of miRNA levels may have diagnostic implications. Evidence shows that numerous viruses interact with the miRNA machinery, and that a number of viruses encode their own miRNAs. It seems likely that miRNAs will be implicated in many human diseases. Manipulation of miRNA levels by gene therapy provides an attractive new approach for therapeutic development. This review focuses on approaches to manipulate miRNA levels in cells and in vivo, and the implications for gene therapy. Furthermore, we discuss the use of endogenous miRNAs as scaffolds for the expression of RNA interference (RNAi) as well as competition between exogenous RNAi triggers and endogenous miRNAs. Because short interfering RNAs can also act as miRNAs, seed matches with the 3' untranslated regions of genes should be avoided to prevent off-target effects. Last, we discuss the use of miRNAs to avoid immune responses to viral vectors.

MicroRNA expression profiling in classic Hodgkin lymphoma

MicroRNAs (miRNAs) are negative regulators of gene expression that play an important role in hematopoiesis and tumorigenesis. We analyzed miRNA expression in classic Hodgkin lymphoma (cHL) and the influence of Epstein-Barr virus (EBV) infection on the miRNA expression profiles. The expression of 157 miRNAs in lymph nodes from 49 cHL patients and 10 reactive lymph nodes (RLNs) was analyzed by real-time polymerase chain reaction (PCR). Hierarchic clustering revealed 3 well-defined groups: nodular sclerosis cHL, mixed cellularity cHL, and RLNs. A distinctive signature of 25 miRNAs differentiated cHL from RLNs, and 36 miRNAs were differentially expressed in the nodular sclerosis and mixed cellularity subtypes. These results were validated in a set of 30 cHLs and 5 RLNs, and in 3 cHL cell lines. miR-96, miR-128a, and miR-128b were selectively down-regulated in cHL with EBV. Our findings suggest that miRNAs play an important role in the biology of cHL and may be useful in developing therapies targeting miRNAs.

New insights into PTEN

The functions ascribed to PTEN have become more diverse since its discovery as a putative phosphatase mutated in many human tumors. Although it can dephosphorylate lipids and proteins, it also has functions independent of phosphatase activity in normal and pathological states. In addition, control of PTEN function is very complex. It is positively and negatively regulated at the transcriptional level, as well as post-translationally by phosphorylation, ubiquitylation, oxidation and acetylation. Although most of its tumor suppressor activity is likely to be caused by lipid dephosphorylation at the plasma membrane, PTEN also resides in the cytoplasm and nucleus, and its subcellular distribution is under strict control. Deregulation of PTEN function is implicated in other human diseases in addition to cancer, including diabetes and autism.

Programmed cell death 4 (PDCD4) is an important functional target of the microRNA miR-21 in breast cancer cells

MicroRNAs are emerging as important regulators of cancer-related processes. The miR-21 microRNA is overexpressed in a wide variety of cancers and has been causally linked to cellular proliferation, apoptosis, and migration. Inhibition of mir-21 in MCF-7 breast cancer cells causes reduced cell growth. Using array expression analysis of MCF-7 cells depleted of miR-21, we have identified mRNA targets of mir-21 and have shown a link between miR-21 and the p53 tumor suppressor protein. We furthermore found that the tumor suppressor protein Programmed Cell Death 4 (PDCD4) is regulated by miR-21 and demonstrated that PDCD4 is a functionally important target for miR-21 in breast cancer cells.

Cancer statistics, 2006

Each year, the American Cancer Society estimates the number of new cancer cases and deaths expected in the United States in the current year and compiles the most recent data on cancer incidence, mortality, and survival based on incidence data from the National Cancer Institute and mortality data from the National Center for Health Statistics. Incidence and death rates are age-standardized to the 2000 US standard million population. A total of 1,399,790 new cancer cases and 564,830 deaths from cancer are expected in the United States in 2006. When deaths are aggregated by age, cancer has surpassed heart disease as the leading cause of death for those younger than age 85 since 1999. Delay-adjusted cancer incidence rates stabilized in men from 1995 through 2002, but continued to increase by 0.3% per year from 1987 through 2002 in women. Between 2002 and 2003, the actual number of recorded cancer deaths decreased by 778 in men, but increased by 409 in women, resulting in a net decrease of 369, the first decrease in the total number of cancer deaths since national mortality record keeping was instituted in 1930. The death rate from all cancers combined has decreased by 1.5% per year since 1993 among men and by 0.8% per year since 1992 among women. The mortality rate has also continued to decrease for the three most common cancer sites in men (lung and bronchus, colon and rectum, and prostate) and for breast and colon and rectum cancers in women. Lung cancer mortality among women continues to increase slightly. In analyses by race and ethnicity, African American men and women have 40% and 18% higher death rates from all cancers combined than White men and women, respectively. Cancer incidence and death rates are lower in other racial and ethnic groups than in Whites and African Americans for all sites combined and for the four major cancer sites. However, these groups generally have higher rates for stomach, liver, and cervical cancers than Whites. Furthermore, minority populations are more likely to be diagnosed with advanced stage disease than are Whites. Progress in reducing the burden of suffering and death from cancer can be accelerated by applying existing cancer control knowledge across all segments of the population.

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.