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.
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.
The role of methylation of 9 miRNA genes in the pathogenesis of metastatic clear cell renal cell carcinoma was determined by quantitative methylation-specific PCR (MS-PCR). For 5 genes (
MIR125B-1
,
...MIR137
,
MIR193A
,
MIR34B/C
, and
MIR375
), a significant correlation of high methylation level with late (III-IV) stages, large size (T3+T4) of the tumor, and metastasis to lymph nodes and/or distant organs was revealed. For another group of genes (
MIR125B-1
,
MIR1258
,
MIR193A
,
MIR34B/C
, and
MIR375
), a statistically significant correlation of high methylation level with loss of differentiation in the tumor (G3-G4) was found, and the opposite pattern was found for
MIR203A
. A total of 7 microRNA genes (
MIR125B-1
,
MIR1258
,
MIR137
,
MIR193A
,
MIR203A
,
MIR34B/C
, and
MIR375
) were identified, the methylation of which is associated with the progression of metastatic clear cell renal cell carcinoma. For 6 of them (except
MIR34B/C
) these data were obtained for the first time. Thus, new factors of the development and progression of clear cell renal cell carcinoma were identified as potential biomarkers for the early diagnosis and prognosis of metastatic clear cell renal cell carcinoma.
The search for interacting long non-coding RNAs (lncRNAs), microRNAs (miRNAs), and mRNAs of protein-coding genes through the mechanism of competing endogenous RNAs in tumors of ovarian cancer ...patients was carried out. The levels of expression of 24 lncRNAs, 20 miRNAs, and 28 mRNAs of protein-coding genes involved in oncogenesis were determined by real-time PCR on a set of representative samples. Correlations between lncRNAs/miRNA and miRNA/mRNA levels in ovarian cancer samples were analyzed. We identified 8 pairs of lncRNAs/miRNA and 17 pairs of miRNA/mRNA, the expression levels of which have a negative correlation. Five triplets of potentially interacting lncRNAs/miRNA/mRNA have been identified, among which the most significant triplet is the
OIP5
-
AS1
/
miR-203a-3p
/
ZEB1
. The data obtained determine new epigenetic profiles, as well as new potential biomarkers and targets for targeted therapy of ovarian cancer patients.
There are three types of metastases in ovarian cancer: lymphogenous, hematogenous, and peritoneal. Dissemination of the tumor in the peritoneum is directly related with the development of ascites and ...a poor prognosis. The purpose of this study is to determine changes in the methylation level of a group of long non-coding RNA (lncRNA) genes at different stages of ovarian cancer progression. The methylation level of 7 lncRNA genes (
LINC00472
,
LINC00886
,
MAFG-DT
,
SNHG1
,
SNHG6
,
TP53TG1
, and
TUG1
) was studied by quantitative methyl-specific PCR in 93 samples of ovarian tumors and 75 paired samples of histologically normal tissue, as well as in 29 peritoneal macroscopic metastases. Using the nonparametric Mann—Whitney test, a significant (
p
<0.001) increase in the level of methylation of the
LINC00886
,
SNHG1
,
SNHG6
, and
TUG1
genes in the tumor tissue was shown. For the
LINC00472
,
LINC00886
, and
SNHG6
genes, a significant relationship was found with the clinical stage (
p
≤0.001), as well as with the appearance of metastases for the
LINC00472
(
p
<0.001) and
SNHG6
(
p
=0.005) genes. There was a significant increase in the level of methylation of
MAFG-DT
and
TP53TG1
(
p
<0.001) genes, as well as a decrease in
LINC00886
(
p
=0.003) in peritoneal metastases relative to the primary focus. Methylation of the
LINC00472
and
SNHG6
genes can be considered as a factor in initiating ovarian cancer metastasis, and methylation of the
LINC00886
,
MAFG-DT
, and
TP53TG1
genes as a colonization factor for metastases in the peritoneum. Thus, a relationship between methylation of a group of lncRNA genes at different stages of ovarian cancer dissemination was shown, which is important for understanding the mechanisms of these processes and for developing innovative approaches to ovarian cancer therapy.
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.
We studied the relationship of the levels of microRNA group expression and methylation with clinical and pathomorphological parameters of breast cancer and its immunohistochemical status. ...Quantitative methylation specific PCR analysis showed a significant (
p
<0.001) increase in the methylation level of 4 microRNA genes (
MIR127
,
MIR129-2
,
MIR132
, and
MIR148A
) and a significant (
p
<0.001) decrease for gene
MIR375
relative to paired histologically normal tissue. Real-time PCR analysis revealed a significant (
p
≤0.001) decrease in the expression of 4 microRNAs (miR-127-5p, miR-129-5p, miR-132-3p, and miR-148a-3p) and a significant (
p
≤0.001) increase in the expression of miR-375-3p. A significant (
rs
=-0.6–-0.7,
p
≤0.001) relationship between changes in the expression level of miR-129-5p, miR-132-3p, miR-148a-3p, and miR-375-3p and the levels of methylation of the corresponding genes in breast cancer was showed by using Spearman’s rank correlation test. Analysis of the samples with consideration of the pathophysiological characteristics of the tumor revealed two significant markers of tumor progression:
MIR129-2
/miR-129-5p and
MIR375
/miR-375-3p. Both factors, the increase in the level of
MIR129-2
methylation (
p
<0.001) and a decrease in the expression level of miR-129-5p (
p
<0.001), are significantly associated (
p
<0.001) with stage III/IV and the absence of HER2 expression. For
MIR375
/miR-375-3p, on the contrary, an association of low methylation level and enhanced expression with increased Ki-67 level (>30%,
p
<0.05) was revealed. These findings are of interest for understanding the mechanisms of breast cancer development and can provide the basis for the diagnosis and prognosis of the course of this disease. Moreover, the revealed features can be useful for adjusting the course of treatment with consideration of the pathophysiological characteristics of the tumor.
Systemic analysis of the relationship between the levels of methylation of 21 microRNA genes and the parameters of breast cancer progression was performed on a representative sample of 91 paired ...specimens of breast cancer and histologically normal tissues and a system of markers for prediction of metastasis was proposed. A significant association of hypermethylation of 11 genes with late (III-IV) clinical stages was found, and for 6 genes (
MIR124-1
,
MIR127
,
MIR34B/C
,
MIR9-3
,
MIR1258
, and
MIR339
) this association was highly significant (
p
≤0.001, FDR=0.01). For
MIR9-3
and
MIR339
, an association with tumor size was demonstrated (
p
<0.001, FDR=0.01). No association of the levels of methylation of the analyzed microRNA genes with the degree of differentiation were found. An association with lymph node metastasis was established for 9 microRNA genes; the most significant association was shown for 6 genes
MIR125B-1
,
MIR127
,
MIR9-3
,
MIR339
,
MIR124-3
, and
MIR1258
(
p
<0.005, FDR=0.05). Based on these 6 genes, a marker system for predicting breast cancer metastasis was developed by ROC analysis. This system is characterized by 87% sensitivity and 77% specificity (AUC=0.894). The proposed system may have clinical application in the personalized treatment of breast cancer patients.
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