MicroRNA - Volume 8, Issue 3, 2019

Background: MicroRNA-125a is present in all animals with bilateral symmetry and displays a conserved nucleotide sequence with a section of 11 bases including the seed region that is identical in all considered species. It primarily downregulates the expression of LIN28, thereby promoting cell differentiation and larval phase transitions in nematodes, mammals and insects. Objective: In this review, we focus on the cellular control of miR-125a expression and its antiproliferative activity. Results: In mammalians, microRNA-125a is present in most adult organs and tissues in which it targets proteins involved in the mitogenic response, such as membrane receptors, intracellular signal transducers, or transcription factors, with the overall effect of inhibiting cell proliferation. Tissue levels of miR-125a generally raise during differentiation but it is often downregulated in cancers, e.g. colon, cervical, gastric, ovarian, lung, and breast cancers, osteosarcoma, neuroblastoma, glioblastoma, medulloblastoma, retinoblastoma and hepatocellular carcinoma. Conclusion: The antiproliferative activity of miR-125a, demonstrated in many cell types, together with the notion that this miRNA is downregulated in several kinds of cancers, give a substantial support to the concept that miR-125a plays an oncosuppressive role.

Background: In cancer therapeutics, several new classes of small molecules based targeted drug options are reported including peptide mimetic and small RNAs therapeutics. Objective: Small RNAs represent a class of short non-coding endogenous RNAs that play an important role in transcriptional and post transcriptional gene regulation among varied types of species including plants and animals. Methods: To address the role of small RNAs from plant sources upon cancer cells, authors report on the effects of small RNAs fraction of potato in in-vitro model of human derived HeLa cancer cells. This paper reports the anti-proliferative and anti-survival effect of small RNAs fraction of S. tuberosum L. (potato) tuber tissue. Here, authors employed small RNAs fractionation protocol, cell viability, cell cytotoxicity MTT, PI stained cell cycle analysis and FITC-Annexin-V/PI stained apoptosis assays. Results: In this paper, small RNAs fractions of potato clearly indicate 40-50% inhibition of HeLa cell proliferation and viability. Interestingly, flow cytometer data point out appreciable increase from 7% to 14% of S-phase in HeLa cells by displaying the presence of an S-phase cell cycle arrest. Further, arrest in S-phase of HeLa cells is also supported by an appreciable increase in total <2N plus >4N DNA containing HeLa cells over 2N containing HeLa cells. For apoptotic assay, data suggest a significant increase in apoptotic HeLa cells from (5%) control treated HeLa cells to (18%) small RNAs treated HeLa cells. Conclusion: Taken together, findings suggest that small RNAs fractions of potato can induce Sphase cell cycle arrest and these agents can act as an anti-proliferative agent in HeLa cells. This paper proposes a huge scope for novel finding to dissect out the small RNAs target within HeLa cells and other cancer cell types.

Background: The recent development of drugs that stabilize HIFalpha, called HIF stabilizers, offers a new strategy for treating anemia. Although these drugs are still in clinical trials, misuse for doping has already begun. Identifying the biomarkers of HIF stabilizers would therefore help in detecting this drug misuse by athletes. Objective: Our aim was twofold: to determine whether hypoxamiRs, the microRNAs associated with the cellular response to hypoxia, are potential biomarkers of HIF stabilizers in blood and whether the response to treatment with an HIF stabilizer differs from the response to a hypoxic environment. Method: Rats were treated for 6 days with either a placebo or 2mg/kg of Molidustat, an HIF stabilizer, or they were put under hypoxia (10% oxygen) for the same length of time. Plasma samples were analyzed before, during and 48 hours after the treatments. Results: EPO concentration increased significantly in plasma during hypoxia and Molidustat treatment and showed a negative retro-control 2 days after the end of the treatments. On the contrary, circulating levels of VEGF were not modified. Among the hypoxamiRs tested, miR-130a and miR-21 were significantly increased during Molidustat treatment and miR-21 was still increased 48 hours after treatment end. Conclusion: Although using these microRNAs as biomarkers seems unlikely due to other possible factors of regulation, this study provides the first identification of a specific effect of HIF stabilizers on microRNAs. Further investigations are needed to better understand the possible consequences of such regulation.

Aim: The microRNAs regulate the expression of multiple genes involved in diseases such as cancer, diabetes and cardiovascular disease. In this study, we have investigated the association between the miR-224 gene polymorphism (rs188519172A>G) and susceptibility of coronary artery disease CAD. Methodology: Hundred CAD patients and 100-matched healthy control were included. Genotyping of the miR-224 (rs188519172A>G) polymorphism was performed using Amplification refractory mutation system PCR method (ARMS-PCR). Results: A significant difference was observed in the genotype distribution among CAD patients and healthy controls (P=0.018). The frequencies of all three genotypes GG, GA, AA reported in the patient’s samples were 33%, 66% and 01%, and in the healthy controls samples, were 16%, 82% and 2% respectively. A multivariate analysis based on logistic regression was conducted for each group to estimate the association between miR-224 rs188519172 genotypes and risk to coronary artery disease. Results show that the miR-224 (rs188519172 A>G) polymorphism was associated with a decreased risk to CAD in a codominant model, GA genotype vs. GG (OR = 0.39 (95 % CI, 0.19-0.76), RR 0.58 (0.38-0.90, P=0.006). In the dominant model, (GA+AA vs. GG), there was also a significant association with the OR=0.38 (95 % CI (0.19-0.76), RR 0.58 (0.38-0.89), and P=0.006. Whereas, in the recessive model, (GG+GA vs. AA), there was no significant association of CAD with OR=0.49 (95% CI (0.044-5.54), RR 0.74 (0.33-1.68), and P=0.48. Conclusion: Our findings indicated that miR-224 (rs188519172) GA genotype is associated with a decreased susceptibility to CAD.

Background and Aim: Lung Cancer (LC) is a major cancer killer worldwide, and 5-yr survival is extremely poor (≤15%), accentuating the need for more effective diagnostic and therapeutic strategies. Studies have shown cell-free microRNAs (miRNAs) circulating in the serum and plasma with specific expression in cancer, indicating the potential of using miRNAs as biomarkers for cancer diagnosis and therapy. This study aimed to identify differentially-expressed two miRNAs in the plasma of Non-Small Cell Lung Cancer (NSCLC) patients that might be a clinically useful tool for lung cancer early detection. miRNA-21 is one of the most abundant oncomirs. miRNA-23a functions as an oncogene in several human cancers, however, its clinical value has not been investigated in NSCLC. Materials and Methods: A case-control study was conducted in Assiut University Hospital, Egypt, from 2017 to 2018. Plasma samples were obtained from 45 NSCLC patients. The expression level of miR-21 and miRNA-23a was detected by qRT-PCR and compared to 40 healthy control subjects. The relation between both miRNAs and clinicopathological parameters was evaluated. Results: The expression level of miR-21 and miRNA-23a was significantly up-regulated (36.9 ± 18.7 vs. 1.12 ± 0.84 and 24.7 ± 19.09 vs. 1.16 ± 0.45) in NSCLC compared to matched controls (P<0.0001each). There was a significant difference in the level of plasma miRNA-21 and miRNA- 23a expression between the different grades of the disease (P = 0.032 and P = 0.001, respectively). The plasma miRNA-21 and miRNA-23a levels in the lung cancer patients with distant metastasis (n = 20) were significantly higher than those in the patients without metastasis (n = 25) (P<0.0001 each), the expression of miR-21 and miRNA-23a was significantly associated with tumor size (P = 0.001, P = 0.0001, respectively), but not significantly related to lymph node metastasis (P = 0.687 and 0.696, respectively). A positive correlation was observed between miRNA-21 and miRNA-23a (r = 0.784, P<0.01), There was no significant difference in the plasma miRNA-21 and miRNA-23a levels in the lung cancer patients with different histopathological types. Conclusion: miR-21 and miR-23a might play an oncogenic role in LC and is a poor prognostic factor. Switching off miRNA-21 and miRNA-23a may improve the treatment of LC. Our results must be verified by large-scale prospective studies with standardized methodology.

Background: MicroRNAs (miRNAs) are short non-coding RNA molecules which regulate gene expression post-transcriptionally and are involved in a multitude of cellular processes. MiRNAs are known to be very stable compared to messenger RNAs (mRNAs), making them excellent candidates as biomarkers for disease. Recently, studies have suggested that miRNA stability in formalin fixed samples might depend on their nucleotide composition. Objective: To explore the stability of a panel of miRNAs isolated from porcine blood and lung tissue after heat and enzyme treatment. Method: Porcine RNA isolated from lung tissue and blood leukocytes was used for this study. RNA samples were exposed to heat treatment and RNAse A digestion. The levels of selected miRNAs were measured by means of qPCR before and after heat and enzyme treatment. Results: Fourteen miRNAs were successfully analysed, and they were found to degrade differently after exposure to heat or RNAse A. MiRNAs with <60% of adenine (A) and uracil (U) in their sequence were found to be more stable. Conclusion: This is the first study showing that different miRNAs isolated from lung tissue display unequal stability after heat treatment, probably based on their nucleotide composition, highlighting the importance of considering the miRNA sequence when investigating their value as biomarkers.

Background: Hypoxia is a pathophysiological condition which arises due to low oxygen concentration in conditions like cardiovascular diseases, inflammation, ascent to higher altitude, malignancies, deep sea diving, prenatal birth, etc. A number of microRNAs (miRNAs), Transcription Factors (TFs) and genes have been studied separately for their role in hypoxic adaptation and controlling cell-cycle progression and apoptosis during this stress. Objective: We hypothesize that miRNAs and TFs may act in conjunction to regulate a multitude of genes and play a crucial and combinatorial role during hypoxia-stress-responses and associated cellcycle control mechanisms. Method: We collected a comprehensive and non-redundant list of human hypoxia-responsive miRNAs (also known as hypoxiamiRs). Their experimentally validated gene-targets were retrieved from various databases and a comprehensive hypoxiamiR-gene regulatory network was built. Results: Functional characterization and pathway enrichment of genes identified phospho-proteins as enriched nodes. The phospho-proteins which were localized both in the nucleus and cytoplasm and could potentially play important role as signaling molecules were selected; and further pathway enrichment revealed that most of them were involved in NFkB signaling. Topological analysis identified several critical hypoxiamiRs and network perturbations confirmed their importance in the network. Feed Forward Loops (FFLs) were identified in the subnetwork of enriched genes, miRNAs and TFs. Statistically significant FFLs consisted of four miRNAs (hsa-miR-182-5p, hsa- miR-146b-5p, hsa-miR-96, hsa-miR-20a) and three TFs (SMAD4, FOXO1, HIF1A) both regulating two genes (NFkB1A and CDKN1A). Conclusion: Detailed BioCarta pathway analysis identified that these miRNAs and TFs together play a critical and combinatorial role in regulating cell-cycle under hypoxia, by controlling mechanisms that activate cell-cycle checkpoint protein, CDKN1A. These modules work synergistically to regulate cell-proliferation, cell-growth, cell-differentiation and apoptosis during hypoxia. A detailed mechanistic molecular model of how these co-regulatory FFLs may regulate the cell-cycle transitions during hypoxic stress conditions is also put forth. These biomolecules may play a crucial and deterministic role in deciding the fate of the cell under hypoxic-stress.

Background: The high mortality rate of breast cancer is related to the occurrence of metastasis, a process that is promoted by tumor angiogenesis. MicroRNAs are small molecules of noncoding mRNA that play a key role in gene regulation and are directly involved in the progression and angiogenesis of various tumor types, including breast cancer. Several miRNAs have been described as promoters or suppressors angiogenesis and may be associated with tumor growth and metastasis. Melatonin is an oncostatic agent with a capacity of modifying the expression of innumerable genes and miRNAs related to cancer. Objective: The aim of this study was to evaluate the role of melatonin and the tumor suppressor miR- 148a-3p on angiogenesis of breast cancer. Method: MDA-MB-231 cells were treated with melatonin and modified with the overexpression of miR-148a-3p. The relative quantification in real-time of miR-148a-3p, IGF-IR and VEGF was performed by real-time PCR. The protein expression of these targets was performed by immunocytochemistry and immunohistochemistry. Survival, migration and invasion rates of tumor cells were evaluated. Finally, the xenograft model of breast cancer was performed to confirm the role of melatonin in the tumor. Results: The melatonin was able to increase the gene level of miR-148a-3p and decreased the gene and protein expression of IGF-1R and VEGF, both in vitro and in vivo. In addition, it also had an inhibitory effect on the survival, migration and invasion of breast tumor cells. Conclusion: Our results confirm the role of melatonin in the regulation of miR-148a-3p and decrease of angiogenic factors.

Introduction: Association studies with factor candidates have advised that single nucleotide polymorphisms (SNPs) could also be related to CML progression and to the response to medical care. Genetic variation in miR-1206 of both derived and neighborhood SNPs process genes will contribute to the predisposition to cancer. The role of those with the risk of CML has not been extensively studied. Therefore, the aim of this study was to evaluate whether polymorphisms in rs2114358 in pre-miRNAs process genes contribute to the risk of CML. Methods: A cross-sectional study was conducted during the period of March 2016 to October 2017 in Khartoum state teaching hospitals. The study population included a total of 420 patients who were previously diagnosed of having CML and 220 cancer-free controls of both gender and were of the same age range. Peripheral blood and bone marrow aspiration samples were collected from patients (254 males, 166 females; median age 58.5 years, range from less than 50 and above 50 years old) and investigated after written informed consent was obtained. Patients were in chronic phase (n=212), accelerated phase (n=125), and blast (n=83). All the patients were under treatment using chemotherapy regiments. The rs2114358 SNP in pre-miRNA was selected for genotyping. Results: The genotyping success rate was 98.3%. Genotype frequencies of the derived SNP and the neighborhood rs2114358 of miR-1206 compared to the controls were significantly different under Hardy-Weinberg Equilibrium (P=0.0001 and 0.0001 respectively). Significant differences were found in allele distributions of this SNP (P<0.01 and P<0.01). In total, the derived variant C allele of rs2114358 (OR=0.168, 95% CI=0.13-0.22) and G allele of neighborhood rs2114358 (OR=0.561, 95% CI=0.44-0.72) in patients' group were associated with an increased risk of CML compared to a control group. Patients with rs2114358 CC genotype (P = 0.0001) or TC (P = 0.0001) and the neighborhood rs2114358 GA genotype (P = 0.0460) or GG (P = 0.0093) were obviously much higher than that of the TT and AA genotype's patients. Conclusion: In conclusion, we discovered the association of SNP rs2114358 in miR-1206 with the risk of CML patients, though more investigations are still required to understand the regulative mechanisms of this miR SNP with the target genes resulting in its dysregulation.