Background: The presence of sequence variants in miRNA genes may influence their processing, expression and binding to target mRNAs. Since single miRNA can have a large number of potential mRNA targets, even minor variations in its expression can have influences on hundreds of putative mRNAs. Methods: Here, we evaluated 101 paired samples (cancer and normal tissues) from non-small cell lung carcinoma (NSCLC) patients to study the genotype distribution of single nucleotide polymorphisms (SNPs) in miR-146a (rs2910164 C-G), miR-149 (rs2292832 C-T), miR-196a2 (rs11614913 C-T) and miR-499 (rs3746444 G-A) and their influence on the expression of respective miRNAs.Results: Relative expression of miR-146a, miR-149 and miR-499 were comparable in NSCLC and in paired control tissues. On the contrary, we clearly detected a significant increase (p-0.001) of miR-196a2 expression in NSCLC. In particular we found a significant association between miR196a2 CC genotype and high expression, whereas TT genotype showed a very low expression in comparison to both CT (p-0.005) and CC patients (p-0.01). We did not find any association between miR-149, miR-196a2 and miR-499 genotype and risk of NSCLC. Conversely, CG genotype of miR-146a appeared associated to an increased risk for NSCLC (ps0.042 and 1.77 OR). Conclusions:Our results seem to demonstrate that sequence variants of miR-196a2 can have an influence on its expression, while miR-146a can have a role in increasing the risk of NSCLC.
a b s t r a c tStudies on miRNA profiling revealed that a large number of them are significantly deregulated in human cancers. The molecular mechanisms of this deregulation are not totally clarified, even if genetics and epigenetics are frequently involved.Single nucleotide polymorphisms (SNPs) are the most common type of genetic variation in the human genome. A SNP into miRNA gene might affect the transcription of primary miRNA, its processing and miRNA-mRNA interaction. We investigated the distribution of sequence variants of miR-146a, miR-196a2, miR-499 and miR-149 in colorectal cancer (CRC) and their effect on miRNA expression. Each variant was identified with HRM. For miR-499 we demonstrated a significant reduction of its expression in CRC connected to a specific genotype.To evaluate the epigenetic effects on miRNA genes in CRC, we investigated the influence of DNA methylation on miR-34b, miR-34c and miR-9-1 expression. We aimed to verify the relationship between the methylation status of these miRNA genes and their relative expression in tumor samples. For the quantification of DNA methylation we adopted a method based on Differential High Resolution Melting (D-HRM).
SUMMARYThe aim of this study was to provide a comprehensive genetic/phenotypic characterization of subjects suffering infertility owing to sperm macrocephaly (n = 3) or globozoospermia (n = 9) and to investigate whether the patients' genetic status was correlated with the alteration of various sperm parameters. AURKC was sequenced in case of sperm macrocephaly while the DPY19L2 status has been analyzed by multiple approaches including a novel qPCR-based copy number assay in case of globozoospermia. Globozoospermic patients were also analyzed for SPACA1, a novel candidate gene herein tested for the first time in humans. The effect of the patients' genetic status was interrogated by implementing the molecular screening with the characterization of several sperm parameters: (i) routine sperm analysis, integrated with transmission electron microscopy; (ii) sperm fluorescent in situ hybridization (FISH) analysis; (iii) sperm DNA fragmentation (DF) analysis. Moreover, for the first time, we performed microsatellite instability analysis as a marker of genome instability in men with sperm macrocephaly and globozoospermia. Finally, artificial reproductive technology (ART) history has been reported for those patients who underwent the treatment. Macrocephalic patients had an AURKC mutation and >89% tetraploid, highly fragmented spermatozoa. DPY19L2 was mutated in all patients with >80% globozoospermia: the two homozygous deleted men and the compound heterozygous showed the severest phenotype (90-100%). The newly developed qPCR method was fully validated and has the potential of detecting also yet undiscovered deletions. DPY19L2 status is unlikely related to FISH anomalies and DF, although globozoospermic men showed a higher disomy rate and DF compared with internal reference values. No patient was mutated for SPACA1. Our data support the general agreement on the negative correlation between macro/ globozoospermia and conventional intracytoplasmic sperm injection outcomes. Microsatellites were stable in all patients analyzed. The comprehensive picture provided on these severe phenotypes causing infertility is of relevance in the management of patients undergoing ART.
DNA methylation is a key regulator of gene transcription. Alterations in DNA methylation patterns are common in most cancers, occur early in carcinogenesis and can be detected in body fluids. Reliable and sensitive quantitative assays are required to improve the diagnostic role of methylation in the management of cancer patients. Here we present an optimized procedure, based on differential-high resolution melting analysis (D-HRMA), for the rapid and accurate quantification of methylated DNA. Two sets of primers are used in a single tube for the simultaneous amplification of the methylated (M) and unmethylated (Um) DNA sequences in D-HRMA. After HRM, differential fluorescence was calculated at the specific melting temperature after automatic subtraction of UM-DNA fluorescence. Quantification was calculated by interpolation on an external standard curve generated by serial dilutions of M-DNA. To optimize the protocol, nine primer sets were accurately selected on the basis of the number of CpG on promoters of hTERT and Bcl2 genes. The use of optimized D-HRMA allowed us to detect up to 0.025% M-DNA. D-HRMA results of DNA from 85 bladder cancers were comparable to those obtained with real time quantitative methylation specific PCR. In addition, D-HRMA appears suitable for rapid and efficient measurements in ‘in vitro’ experiments on methylation patterns after treatment with demethylating drugs.
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