[Methylation of the genes for the microRNAs miR-129-2 and miR-9-1, changes in their expression, and activation of their potential target genes in clear cell renal cell carcinoma]

Overview of host miRNA properties and their association with epigenetics, long non-coding RNAs, and Xeno-infectious factors

MicroRNA-derived structures play impressive roles in various biological processes. So dysregulation of miRNAs can lead to different human diseases. Recent studies have extended our comprehension of the control of miRNA function and features. Here, we overview some remarkable miRNA properties that have potential implications for the miRNA functions, including different variants of a miRNA called isomiRs, miRNA arm selection/arm switching, and the effect of these factors on miRNA target selection. Besides, we review some aspects of miRNA interactions such as the interaction between epigenetics and miRNA (different miRNAs and their related processing enzymes are epigenetically regulated by multiple DNA methylation enzymes. moreover, DNA methylation could be controlled by diverse mechanisms related to miRNAs), direct and indirect crosstalk between miRNA and lnc (Long Non-Coding) RNAs as a further approach to conduct intercellular regulation called "competing endogenous RNA" (ceRNA) that is involved in the pathogenesis of different diseases, and the interaction of miRNA activities and some Xeno-infectious (virus/bacteria/parasite) factors, which result in modulation of the pathogenesis of infections. This review provides some related studies to a better understanding of miRNA involvement mechanisms and overcoming the complexity of related diseases that may be applicable and useful to prognostic, diagnostic, therapeutic purposes and personalized medicine in the future.

MicroRNA Signature in Renal Cell Carcinoma

Renal cell carcinoma (RCC) includes 2.2% of all diagnosed cancers and 1.8% of cancer-related mortalities. The available biomarkers or screening methods for RCC suffer from lack of sensitivity or high cost, necessitating identification of novel biomarkers that facilitate early diagnosis of this cancer especially in the susceptible individuals. MicroRNAs (miRNAs) have several advantageous properties that potentiate them as biomarkers for cancer detection. Expression profile of miRNAs has been assessed in biological samples from RCC patients. Circulatory or urinary levels of certain miRNAs have been proposed as markers for RCC diagnosis or follow-up. Moreover, expression profile of some miRNAs has been correlated with response to chemotherapy, immunotherapy or targeted therapeutic options such as sunitinib. In the current study, we summarize the results of studies that assessed the application of miRNAs as biomarkers, therapeutic targets or modulators of response to treatment modalities in RCC patients.

Molecular Mechanisms in Clear Cell Renal Cell Carcinoma: Role of miRNAs and Hypermethylated miRNA Genes in Crucial Oncogenic Pathways and Processes

Clear cell renal cell carcinoma (ccRCC) is the third most common urological cancer, and it has the highest mortality rate. The increasing drug resistance of metastatic ccRCC has resulted in the search for new biomarkers. Epigenetic regulatory mechanisms, such as genome-wide DNA methylation and inhibition of protein translation by interaction of microRNA (miRNA) with its target messenger RNA (mRNA), are deeply involved in the pathogenesis of human cancers, including ccRCC, and may be used in its diagnosis and prognosis. Here, we review oncogenic and oncosuppressive miRNAs, their putative target genes, and the crucial pathways they are involved in. The contradictory behavior of a number of miRNAs, such as suppressive and anti-metastatic miRNAs with oncogenic potential (for example, miR-99a, miR-106a, miR-125b, miR-144, miR-203, miR-378), is examined. miRNAs that contribute mostly to important pathways and processes in ccRCC, for instance, PI3K/AKT/mTOR, Wnt-β, histone modification, and chromatin remodeling, are discussed in detail. We also separately consider their participation in crucial oncogenic processes, such as hypoxia and angiogenesis, metastasis, and epithelial-mesenchymal transition (EMT). The review also considers the interactions of long non-coding RNAs (lncRNAs) and miRNAs of significance in ccRCC. Recent advances in the understanding of the role of hypermethylated miRNA genes in ccRCC and their usefulness as biomarkers are reviewed based on our own data and those available in the literature. Finally, new data and perspectives concerning the clinical applications of miRNAs in the diagnosis, prognosis, and treatment of ccRCC are discussed.

CHL1 gene polymorphisms increase lung cancer susceptibility

Lung cancer represents a complex and malignant cancer. Close Homologue of L1 (CHL1) gene plays a crucial role in the progress of cancer. The aim of this study is to explore the association between CHL1 rs425366 polymorphism and lung cancer susceptibility in northeast of China. A hospital-based case-control study was carried out to collect relative characteristics. Logistic regression analysis was conducted to analyze the relationship between single nucleotide polymorphisms and lung cancer susceptibility. The results suggested that there was statistically significant difference between GT genotype and TT genotype of rs425366 and lung cancer susceptibility. In stratified analysis, TT genotype of rs425366 may increase the risk of lung adenocarcinoma. We also found that non-smoking individuals carrying T allele were more likely to develop lung cancer. Overall, our study may indicate that CHL1 gene may increase lung cancer susceptibility in northeast of China.

NDUFA4L2 is associated with clear cell renal cell carcinoma malignancy and is regulated by ELK1

Background

Clear cell renal cell carcinoma (ccRCC) is the most common and lethal cancer of the adult kidney. However, its pathogenesis has not been fully understood till now, which hinders the therapeutic development of ccRCC. NADH dehydrogenase (ubiquinone) 1 alpha subcomplex 4-like 2 (NDUFA4L2) was found to be upregulated and play an important role in ccRCC. We aimed to further investigate the underlying mechanisms by which NDUFA4L2 exerted function and its expression level was upregulated.

Methods

The Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) data were mined to verify the change of NDUFA4L2 expression level in ccRCC tissues. The correlation between expression level of NDUFA4L2 and cell proliferation/apoptosis was explored by Gene Set Enrichment Analysis (GSEA). Protein-protein interaction (PPI) network of NDUFA4L2 was constructed. Biological process and involved pathways of NDUFA4L2 were analyzed by gene ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway. The transcription factors (TFs) which can induce the expression of NDUFA4L2 were explored in clinical samples by correlation analysis and its regulation on the expression of NDUFA4L2 was verified by knockdown experiment.

Results

NDUFA4L2 was verified to be overexpressed in ccRCC tissues and its expression level was increased accordingly as the American Joint Committee on Cancer (AJCC) stage progressed. A high NDUFA4L2 level predicted the poor prognosis of ccRCC patients and correlated with enhanced cell proliferation and anti-apoptosis. NDUFA4L2 may interact with 14 tumor-related proteins, participate in growth and death processes and be involved in ccRCC-related pathways, such as insulin-like growth factor 1 (IGF-1), mammalian target of Rapamycin (mTOR) and phosphoinositide 3 kinase serine/threonine protein kinase (PI3K/AKT). ETS domain-containing protein ELK1 level positively correlated with the level of NDUFA4L2 in ccRCC tissues and ELK1 could regulate the expression of NDUFA4L2 in ccRCC cells.

Discussion

NDUFA4L2 upregulation was associated with ccRCC malignancy. NDUFA4L2 expression was regulated by ELK1 in ccRCC cells. Our study provided potential mechanisms by which NDUFA4L2 affected ccRCC occurrence and progression.