[Relevance of microRNA-s in neoplastic diseases]

Comparative miRNA Expression Profile Analysis of Squamous Cell Carcinoma and Peritumoral Mucosa from the Meso- and Hypopharynx

BACKGROUND/AIM

The role of microRNAs (miRNA) in carcinogenesis is related to their genome-regulatory function. The aim of the present study was to identify and compare miRNA expression signatures of meso- and hypopharynx squamous cell cancers in consideration of the cancer field hypothesis.

PATIENTS AND METHODS

Thirteen snap-frozen biopsy series of tumors and peritumoral tissues from the meso- and hypopharynx were analyzed regarding their miRNA expression with quantitative real-time polymerase chain reaction (qRT-PCR).

RESULTS

Significant miRNA expression changes of miR-21, -27a, -34a, -143 and -146a were found in peritumoral tissues that were dependent from the tumor location and the distance from the primary tumor site.

CONCLUSION

miRNA expression analysis was found to be appropriate for molecular segregation of tumor location and peritumoral tissue segments, and appears to be a promising marker for cancer field characterization.

[MicroRNA expression profiles in squamous cell carcinomas of the meso- and hypopharynx]

INTRODUCTION

MicroRNAs play a role in carcinogenesis through their genome regulatory function.

AIM

The aim of the authors was to identify and compare microRNA expression signatures of meso- and hypopharynx squamous cell cancers on the basis of the cancer field hypothesis.

METHOD

Using standard mapping biopsy (tumour tissue and macroscopically normal tissues obtained 1, 2 and 3 cm from margin) 13 snap frozen sample series were analysed for microRNA expression with quantitative real-time polymerase chain reaction.

RESULTS

MiR-221 was significantly overexpressed in mesopharynx cancers, whole miR-21, miR-143 and miR-155 showed significant overexpression in hypopharynx cancers.

CONCLUSIONS

Using microRNA expression profiles the authors were able to distinguish peritumoural tissues according to distance from the primary tumour site. Future application of the method may prove to be useful in early detection of the altered epigenetic regulation in tissue fields representing normal phenotype. This may be helpful in cancer risk assessment and prevention.

Genetics of neuroendocrine tumours, hereditary tumour syndromes

Neuroendocrine tumours occur in some hereditary tumour syndromes, and the molecular pathophysiological mechanisms involved in these are also important in their sporadic counterparts which representing the majority of neuroendocrine tumours. These syndromes include multiple endocrine neoplasia type 1, von Hippel–Lindau syndrome, neurofibromatosis type 1 and tuberous sclerosis. All these follow an autosomal dominant inheritance. The primarily affected molecular pathways are Ras-MAPK signalling, hypoxia induced factor 1α, and mTOR signalling that are also involved in sporadic tumours and may even represent potential molecular targets of therapy. In this review, the major characteristics of hereditary tumour syndromes, their molecular genetics and the pathophysiological mechanisms involved in sporadic tumours are discussed. Orv. Hetil., 2013, 154, 1541–1548.

[MicroRNA-profiling in breast- and salivary gland-derived adenoid cystic carcinomas]

INTRODUCTION

Adenoid cystic carcinoma is a salivary gland-derived malignant tumor, but rarely it can originate from the breast, too. The salivary gland-derived form shows a very aggressive clinical outcome, while adenoid cystic carcinoma of the breast has mostly a very good prognosis.

AIM

The aim of the authors was to compare the miRNA-expression profile of breast- and salivary gland-derived cases.

METHOD

The miRNA-profiles of two salivary gland derived and two breast-derived adenoid cystic carcinoma tissues as well as one normal breast and one salivary gland tissues were analysed using the Affymetrix® Gene Chip.

RESULTS

The expression of some miRNAs differed in the tumor tissues compared to their controls: the let-7b was overexpressed in salivary gland-derived adenoid cystic carcinoma, while decreased in breast-derived adenoid cystic carcinoma. In addition, the miR-24 was decreased in salivary gland-derived but overexpressed in breast-derived adenoid cystic carcinomas. The miR-181a-2* was only detected in salivary gland-derived adenoid cystic carcinomas.

CONCLUSIONS

Through post-transcriptional regulation of the genes, the diverse expression of some miRNAs may partially explain the diverse clinical outcome of salivary gland-derived and breast-derived adenoid cystic carcinomas.

[Potential role for microRNAs in inter-individual and inter-species communication]

MicroRNAs are major regulators of gene expression at the posttranscriptional level. Besides being detected intracellularly, microRNAs have been found in body fluids, as well. Circulating microRNAs may have hormone like features, since they might affect distant cells as mediators of intercellular communication. MicroRNAs occurring in serum, urine, stool and saliva can be exploited as biomarkers of several diseases, and intensive research efforts are being performed in this field. MicroRNAs are also found in breast milk, and it cannot be excluded that these may act on the baby as a form of inter-individual transfer of epigenetic information. The presence of food-derived microRNAs is even more astonishing, thus plant microRNAs have been detected in the circulation, and these could be functionally active in the human/animal organism. Based on these observations, microRNAs could be involved in the transfer of gene expressional/epigenetic information between different individuals, but also between different species, even cross-kingdom. This microRNA-mediated communication might alter our concepts on the functioning of nature and on the development of diseases, as well.

[Relevance of long non-coding RNAs in tumour biology]

The discovery of the biological relevance of non-coding RNA molecules represents one of the most significant advances in contemporary molecular biology. It has turned out that a major fraction of the non-coding part of the genome is transcribed. Beside small RNAs (including microRNAs) more and more data are disclosed concerning long non-coding RNAs of 200 nucleotides to 100 kb length that are implicated in the regulation of several basic molecular processes (cell proliferation, chromatin functioning, microRNA-mediated effects, etc.). Some of these long non-coding RNAs have been associated with human tumours, including H19, HOTAIR, MALAT1, etc., the different expression of which has been noted in various neoplasms relative to healthy tissues. Long non-coding RNAs may represent novel markers of molecular diagnostics and they might even turn out to be targets of therapeutic intervention.

[MicroRNAs in hepatocarcinogenesis]

The details of molecular alterations occurring during hepatocarcinogenesis have not been revealed yet. Nevertheless, it is known that microRNAs (miRNA), these short RNA molecules regulating gene expression mainly in a negative way, are also involved in this process. Altered miRNA expression levels are present in liver diseases when compared with normal liver tissue, and the observed alterations depend mainly on which is more advantegous for the disease: activation or inhibition of the genes (e.g. oncogenes or tumor suppressor genes) regulated by the altered miRNAs. The miRNA expression pattern described in hepatocellular carcinoma seems to differ the most from that found in the normal liver; however, remarkable alterations at miRNA levels have been published in early stages of hepatic tumor progression such as fibrosis and chronic hepatitis. For example, the expression of miR-21, miR-221, miR-222 and miR-199a showing characteristic alterations in hepatocellular carcinoma also displayed deregulated expressions in these two early stages. The liver characteristic miRNA, miR-122, usually exhibits a decreased expression level upon liver injury as well as miR-122 expression tends to decrease as hepatic carcinogenesis progresses. Besides, miR-122 enhances the replication of hepatitis C virus and the initial low or high level of miR-122 seems to influence the efficiency of interferon therapy. Recently, statistically significant differences have been detected in the expression of several miRNAs being present in the serum of patients with chronic hepatitis, chirrhosis and hepatocellular carcinoma when compared with normal controls. It suggests that serum miRNAs could be potential biomarkers. In this article, the major and recent alterations of microRNA expression patterns in stages of hepatocarcinogenesis such as fibrosis, viral infections (hepatitis), cirrhosis and hepatocellular carcinoma are summarized.

Impact of microRNAs on molecular epidemiology

Cancer research concerning short non-coding RNA sequences and functionally linked to RNA interference (RNAi) have reached explosive breakthrough in the past decade. Molecular technology applies microRNA in extremely wide spectrum from molecular tumor prediction, diagnostics, progression monitoring and prevention. Functional analysis of tissue miRNA and cell-free serum miRNA in posttranscription and translation regulation innovated and restructured the knowledge on the field. This review focuses on molecular epidemiology and primary prevention aspects of the small non-coding RNA sequences. Orv. Hetil., 2011, 152, 633–641.

[Alterations in microRNA expression patterns in liver diseases]

In the past few years there has been growing interest for a type of short RNAs called microRNAs, which are involved in the regulation of gene expression mainly in a negative way. There are about 1000 known microRNA today. It has been demonstrated that expression level of microRNA may become altered from normal to diseased state, thus microRNAs could be employed as a reliable tool in the diagnosis of diseases. A liver-characteristic microRNA (miR-122) needed for functioning hepatocytes has been identified, which usually shows a decreased expression level upon liver injury. miR-122 has been suggested as a biomarker since it was downregulated in the liver tissue upon acetaminophen-induced toxicity and in turn elevated miR-122 level was detected in the plasma. Moreover, miR-122 level in the plasma was found to be more sensitive as compared with conventional assays based on the release of liver enzymes. Also, miR-122 expression tends to decrease as carcinogenesis progresses. In addition, miR-122 enhances the replication of hepatitis C virus and its level seems to influence the efficiency of interferon therapy. Nowadays, many microRNAs are known whose distinctive alterations in their specific patterns seem to characterize individual pathological processes. In this article, the major alterations in microRNA expression patterns in liver diseases such as drug- and alcohol-induced liver diseases, non-alcoholic fatty liver diseases, fibrosis, viral infections (hepatitis), cirrhosis and hepatocellular carcinoma are summarized.

Pathogenesis of adrenocortical cancer

A mellékvesekéreg-carcinoma ritka, rossz prognózisú daganat. Döntően sporadikus előfordulású, de ismertek nagyon ritka öröklődő formái is, amelyek a patogenezis megértésében nagy segítséget nyújtanak. A mellékvesekéreg-daganatokra hajlamosító öröklődő szindrómák közé tartozik a Li–Fraumeni-szindróma, a Beckwith–Wiedemann-szindróma, a familiáris adenomatosus polyposis, illetve a döntően benignus daganatokkal társuló multiplex endokrin neoplasia 1-es típusa (MEN1), Carney-komplex és McCune–Albright-szindróma. A mellékvesekéreg-daganatok patogenezisében szereplő főbb mechanizmusok közé tartozik az inzulinszerű növekedési faktor-2 fokozott expressziója, a Wnt/β-katenin és a cAMP-proteinkináz-A jelátviteli utak aktivációja, valamint a p53 és MEN1 gének mutációi. A mellékvesekéreg-carcinoma kezelésében a gyógyszeres lehetőségek meglehetősen korlátozottak. Az utóbbi évek molekuláris-bioinformatikai kutatásai számos eddig ismeretlen patogenetikai út szerepét vetették fel, amelyek új gyógyszeres támadáspontok lehetőségét is jelenthetik. E tanulmányban a szerzők az öröklődő daganatszindrómák patogenezisét, a sporadikus daganatokban észlelt eltéréseket és a legújabb molekuláris-bioinformatikai eredményeket ismertetik.