Interaction between microRNA (miRNA) and messenger RNA of target genes at the posttranscriptional level provides fine-tuned dynamic regulation of cell signaling pathways. Each miRNA can be involved ...in regulating hundreds of protein-coding genes, and, conversely, a number of different miRNAs usually target a structural gene. Epigenetic gene inactivation associated with methylation of promoter CpG-islands is common to both protein-coding genes and miRNA genes. Here, data on functions of miRNAs in development of tumor-cell phenotype are reviewed. Genomic organization of promoter CpG-islands of the miRNA genes located in inter- and intragenic areas is discussed. The literature and our own results on frequency of CpG-island methylation in miRNA genes from tumors are summarized, and data regarding a link between such modification and changed activity of miRNA genes and, consequently, protein-coding target genes are presented. Moreover, the impact of miRNA gene methylation on key oncogenetic processes as well as affected signaling pathways is discussed.
We analyzed changes in the level of methylation of CpG islands in four long non-coding RNA (lncRNA) genes
MEG3
,
ZNF667-AS1
,
GAS5
, and
SEMA3B-AS1
as promising markers of breast cancer. Methylation ...analysis was performed by quantitative methylation-specific PCR on a set of 38 paired (tumor/normal) breast cancer samples. Significantly (
p
<0.001) increased methylation was shown for three of the four lncRNA genes:
MEG3
,
ZNF667-AS1
, and
SEMA3B-AS1
. We found significant correlations of the methylation level of all the studied lncRNA genes with the stage of cancer and with lymphogenic metastasis, and for
MEG3
and
ZNF667-AS1
also with the tumor size. Methylation of
ZNF667-AS1
, and
SEMA3B-AS1
genes in breast cancer was detected for the first time. Based on these findings, new potential markers for the diagnosis and prognosis of breast cancer can be proposed.
We studied changes in the level of methylation of a number of microRNA genes hypermethylated in non-small cell lung cancer and its histological subtypes as well as the relationship of methylation of ...a group of microRNA genes with clinical and morphological features of the tumor with smoking status. A significantly high level of methylation of 7 genes (
MIR124-1/3
,
MIR125B-1
,
MIR129-2
,
MIR137
,
MIR1258
, and
MIR339
) was revealed in adenocarcinoma and squamous cell lung cancer in comparison with samples of adjacent histologically unchanged lung tissue. In squamous cell lung cancer, a significantly high level of methylation of the
MIR124-2
gene in the tumor was also shown. In addition, differences in the methylation profile of adenocarcinoma and squamous cell carcinoma at stages III-IV of the oncological process were revealed. A high level of methylation of the
MIR137
and
MIR1258
genes was shown for adenocarcinoma and
MIR339
,
MIR129-2
, and
MIR124-2
for squamous cell carcinoma. Significant differences in the level of methylation of
MIR124-2
and
MIR375
genes were revealed for smoking patients with squamous cell lung cancer.
Average daily air temperature and daily total precipitation were analyzed using quantile regression. Quantiles corresponding to the selected extremes, i.e., below 0.1 (only for the analysis of air ...temperature) and above 0.9 were considered. It has been shown for the majority of cases that the spatial distribution of air temperature quantiles is close to the mean for winter and summer seasons. Specific features of temporal changes in the quantiles of air temperature and total precipitation are in line with the modern climate warming. A statistically significant relationship between air temperature and Earth surface characteristics is observed only for quantiles of 0.9 and more. Due to the complexity of the factors responsible for the formation of high-intensity precipitation, there is no clear pattern in the spatial distribution of the quantiles of daily total precipitation. There is statistically significant relationship between daily total precipitation, orography, and forest cover fraction on the territory.
Networks for data transmission between objects of V2X intelligent transport systems are currently being actively developed. Most existing V2X networks operate based on the IEEE 802.11p standard. ...However, these networks can only provide basic V2X applications and are unable to meet the demands of today’s applications. As a result, the IEEE committee began developing a new IEEE 802.11bd standard. A significant innovation of this standard is the use of the channel bonding method, which allows data to be transmitted in several channels at once. One of the approaches that can significantly increase the efficiency of the channel bonding method is the correct selection of the contention window. In this paper, we propose an adaptive algorithm for selecting a contention window that is compatible with the channel bonding method, is easy to implement, does not require changes to existing devices, and takes into account the requirements for the quality of service of various types of traffic. Using simulation it is shown that the proposed algorithm increases the maximal allowable density of stations, at which the requirements for quality of service are still met, by 25% compared to the standardized solution.
New Radio-Unlicensed (NR-U) is a technology that allows fifth generation mobile networks to utilize unlicensed frequency bands, in particular, the 5 GHz band. To increase throughput, an NR-U base ...station (gNB) can simultaneously operate in several frequency channels within the 5 GHz band. However, the gNB cannot always transmit data through one channel and, at the same time, perform the channel access procedure in another channel due to the out-of-band emission problem, which leads to channel underutilization. As a result, the throughput of NR-U networks can heavily depend on the out-of-band emission level. In this paper, by means of simulation, the impact of out-of-band emissions on NR-U performance is studied when NR-U uses all channel access methods defined in the specification. It is shown that the out-of-band emission level affects the choice of channel access method optimal in terms of throughput. We also show that out-of-band emissions do not always have a negative impact on NR-U performance; sometimes they make it possible to achieve more than 30% throughput gain.
We studied the correlations between the levels of methylation of a group of 21 microRNA genes in 99 primary tumors and 29 macroscopic peritoneal metastases of ovarian cancer. Analysis of the level of ...methylation by quantitative methylation-specific PCR showed that co-methylation was detected for 13 pairs of microRNA genes in primary tumors and for 22 pairs in metastases. Pairs of microRNA genes that have shown significant co-methylation can be involved in common processes and pathways of gene regulation and interaction and can have common target genes. The results are highly significant and pairs of microRNA genes can be proposed as new potential markers for the diagnosis and prognosis of ovarian cancer metastasis.
We studied the effect of functionally significant polymorphic markers of the
ESR1
gene on the risk of breast cancer, tamoxifen resistance, and survival of patients with this type of cancer. The study ...included 239 primary breast cancer patients without distant metastases. The analysis of genotype frequency distribution for the studied
ESR1
gene polymorphic markers showed the association of the
rs2228480
and
rs2234693
markers with tamoxifen resistance in the group of patients with luminal B type breast cancer. An association of these two polymorphic markers with the risk of tumor development was also revealed; for
rs2234693
polymorphic marker, a relationship with the survival of patients was also showed.
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