MicroRNA-137 targets carboxyl-terminal binding protein 1 in melanoma cell lines

MicroRNAs in the pathogenesis of malignant melanoma

Cutaneous malignant melanoma is the most aggressive and lethal form of skin cancer. Over the past decades, its incidence has been increasing by 3-8% per year in western countries while mortality has stabilized. Melanoma is a heterogenous disease and can be subclassified based on distinct clinical characteristics, histopathological features and mutation patterns within NRAS and BRAF genes. Recent data indicate that microRNAs (miRNAs) are involved in the pathogenesis of malignant melanoma. MiRNAs are small, non-coding, regulatory RNA molecules expressed in a tissue and cell specific manner and are known to play a crucial role in cell homeostasis and carcinogenesis. MiRNAs might prove to be powerful cancer biomarkers and future therapeutic targets. In this review, we focused on the miRNA involvement in four molecular pathways known to be deregulated in malignant melanoma, including the RAS-RAF-MEK-ERK pathway, the p16(INK4A) -CDK4-RB pathway, the PIK3-AKT pathway and the MITF pathway.

Genetics and epigenetics of cutaneous malignant melanoma: a concert out of tune

Cutaneous malignant melanoma (CMM) is the most life-threatening neoplasm of the skin and is considered a major health problem as both incidence and mortality rates continue to rise. Once CMM has metastasized it becomes therapy-resistant and is an inevitably deadly disease. Understanding the molecular mechanisms that are involved in the initiation and progression of CMM is crucial for overcoming the commonly observed drug resistance as well as developing novel targeted treatment strategies. This molecular knowledge may further lead to the identification of clinically relevant biomarkers for early CMM detection, risk stratification, or prediction of response to therapy, altogether improving the clinical management of this disease. In this review we summarize the currently identified genetic and epigenetic alterations in CMM development. Although the genetic components underlying CMM are clearly emerging, a complete picture of the epigenetic alterations on DNA (DNA methylation), RNA (non-coding RNAs), and protein level (histone modifications, Polycomb group proteins, and chromatin remodeling) and the combinatorial interactions between these events is lacking. More detailed knowledge, however, is accumulating for genetic and epigenetic interactions in the aberrant regulation of the INK4b-ARF-INK4a and microphthalmia-associated transcription factor (MITF) loci. Importantly, we point out that it is this interplay of genetics and epigenetics that effectively leads to distorted gene expression patterns in CMM.

MicroRNA-7 inhibits the growth of human non-small cell lung cancer A549 cells through targeting BCL-2

MicroRNAs(miRNAs) are emerging as important regulators in tumorigenesis. Increasing evidences have indicated microRNA-7(miR-7) to be a potential tumor suppressor in several human cancers. However, only a limited number of target genes have been identified so far and its biological function in Non-Small Cell Lung Cancer (NSCLC) remains to be further elucidated. In the present study, we observed a reduction of miR-7 level in NSCLC cell lines. Overexpression of miR-7 not only suppressed NSCLC A549 cells proliferation, induced cell apoptosis and inhibited cell migration in vitro, but also reduced tumorigenicity in vivo. Bioinformatics predictions revealed a potential binding site of miR-7 on 3'UTR of BCL-2 and it was further confirmed by luciferase assay. Moreover, subsequent experiments showed that BCL-2 was downregulated by miR-7 at both transcriptional and translational levels. These results suggest that miR-7 regulates the expression of BCL-2 through direct 3'UTR interactions. Therefore, we postulate BCL-2 to be a novel target possibly involved in miR-7-mediated growth suppression and apoptosis of A549 cells. These findings may provide a basic rationale for the use of miR-7 in the treatment of NSCLC.

Identification of MicroRNAs involved in hypoxia- and serum deprivation-induced apoptosis in mesenchymal stem cells

The use of bone marrow mesenchymal stem cell- (MSC) transplantation therapy for cardiac diseases is limited due to poor survival of implanted cells. MicroRNAs (miRNAs) have been reported to be involved in regulating almost all cellular processes, including apoptosis. In this study, we found that the miRNA profile was altered during apoptosis induced by hypoxia and serum deprivation (hypoxia/SD). We further revealed that over-expression of miR-21, miR-23a and miR-210 could promote the survival of MSCs exposed to hypoxia/SD. In contrast, down-regulation of miR-21, miR-23a and miR-503 aggravated apoptosis of MSCs. It was indicated that these miRNAs may play important roles during MSC apoptosis induced by hypoxia/SD.

MiR-34a in age and tissue related radio-sensitivity and serum miR-34a as a novel indicator of radiation injury

MiR-34a, a direct target of p53, has shown to exert potent anti-proliferative effects. It has also been found that miR-34a can be induced by irradiation in vitro and in vivo. However, the relationship between miR-34a and radio-sensitivity, and its potential diagnostic significance in radiation biology, remain unclear. This study found that differing responses to ionizing radiation (IR) of young and adult mice were related to miR-34a. First, we found that miR-34a could be induced in many organs by radiation of both young and adult mice. However, the level of miR-34a induced by young mice was much higher when compared to adult mice. Next, we found that miR-34a played a critical role in radio-sensitivity variations of different tissues by enhancing cell apoptosis and decreasing cell viability. We also found that the induction of miR-34a by radiation was in a p53 dependent manner and that one possible downstream target of miR-34a that lead to different radio-sensitivity was the anti-apoptosis molecular Bcl-2. However, over-expression of miR-34a and knockdown of Bcl-2 could significantly enhance the radio-sensitivity of different cells while inhibition of miR-34a could protect cells from radiation injury. Finally, we concluded that miR-34a could be stable in serum after IR and serve as a novel indicator of radiation injury. Taken together, this data strongly suggests that miR-34a may be a novel indicator, mediator and target of radiation injury, radio-sensitivity and radioprotection.