MicroRNAs play an important role in the regulation of expression of many genes and are involved in carcinogenesis. The regulation of miRNA gene expression can involve the methylation of promoter CpG ...islands. In this work, the methylation of six miRNA genes (
mir-107, mir-125b-1, mir-130b, mir-137, mir-375
, and
mir-1258
) in non-small-cell lung cancer (NSCLC) was studied for the first time by methylation-specific PCR using a representative set of specimens (39 cases). Four new genes (
mir-125b-1, mir-137, mir-375
, and
mir-1258
) methylated in primary NSCLC tumors were identified with frequencies of 56, 31, 56, and 36%, respectively. The frequencies of miRNA promoter methylation in DNA of tumors and histologically normal tissues differed significantly (
P
≤ 0.05 by Fisher’s test). In lung tissues of 20 donors without a history of cancer, these genes were only methylated in a few cases. It was also shown that the previously unstudied promoter CpG islands of
mir-107
and
mir-130b
were not methylated in NSCLC. The frequencies of
mir-125b-1
and
mir-137
methylation were shown for the first time to correlate with NSCLC progression (clinical stage and metastasis).
A current approach of oncogenomics is the search for genes with expression that makes it possible to specify the type of breast cancer (BC) and the prognosis of the disease due to different tumor ...status. By real-time PCR analysis on a 41 BC samples set, the relationship between mRNA expression levels of five tumor-associated genes (
BCL6
,
CHL1
,
AXL
,
ACSL1
,
TGFB2
) and seven potentially regulatory microRNAs (miR-132-3p, miR-137, miR-148a-3p, miR-219-5p, miR-24-2-5p, miR-339-3p, miR-375) to clinical and pathological parameters of tumors and immunohistochemical status was characterized. A decrease in the expression level of
CHL1
and
AXL
and an increase in the expression level of
BCL6
revealed in the late stages of breast cancer were shown. In addition, stages III and IV of breast cancer are associated with an increase in the miR-339-3p expression level, and lymph node metastases are associated with a decrease in the miR-148a-3p expression level. It was noted that a high rate of Ki-67 proliferation is related to an increase in the miR-375 expression level. Tumors that do not express the progesterone receptor (PR) show decreased expression levels of
BCL6
, miR-375, and miR-24-2-5p. A decreased expression level of
BCL6
was also observed in breast cancer with a negative estrogen receptor (ER–) status. In breast cancer samples with a negative HER2 status, a statistically significant decreased expression level of the gene
TGFB2
and miR-219-5p was noted, and also a decreased expression level of
TGFB2
was found in luminal A of BC. Thus, we identified possibly new molecular indicators of breast cancer progression and biomarkers that can be useful in the differential diagnosis of the molecular subtype of breast cancer.
To date, there are more than 2000 known human miRNAs, each of which may be involved in the regulation of hundreds of protein-coding target genes. In turn, the methylation of CpG islands affects the ...miRNA gene expression. Our aim was to evaluate the role of methylation in the regulation of miRNA gene expression and, consequently, in the regulation of the expression of target genes in primary lung tumors. Using a common collection of samples of non-small-cell lung cancer, we have performed a comprehensive study, including an analysis of the methylation status and level of expression of some miRNA genes and their potential target genes on chromosome 3, i.e.,
RAR-beta2
and
NKIRAS1
. The increased frequency of methylation in lung tumors compared to histologically normal tissue was revealed for
miR-9-1
and
miR-34b
/
c
genes with significant statistics (
P
< 0.05 by Fisher’s exact test) and for
miR-9-3
and
miR-193a
was marginally significant (
P
< 0.1). A significant correlation was revealed between the changes in methylation and level of expression of
miR-9-1
gene (
P
≈ 5 × 10
−12
by Spearman) in lung tumors, which suggests the role of methylation in the regulation of expression of these miRNA genes. Furthermore, a statistically significant negative correlation (
P
≈ 3 × 10
−12
to 5 × 10
−13
by Spearman) was found between changes in the levels of expression of
miR-9-1
and
miR-17
and
RAR-beta2
target genes, as well as between the changes in the level of expression of
miR-17
and
NKIRAS1
that were not previously analyzed. The inverse relationship between the levels of expression of miRNA genes and their target genes is consistent with the known mechanism of the suppression of the expression of protein-coding genes under the action of miRNA. For the first time, significant correlations (
P
≈ 3 × 10
−10
to 4 × 10
−13
by Spearman) were shown between changes in the methylation status of miRNA genes (
miR-9-1, miR-9-3, miR-34b/c, miR-193a
) and the level of expression of the
RAR-beta2
target gene and changes in the methylation status of
miR-34b/c
, and
miR-193a
and the level of expression of the
NKIRAS1
target gene in the primary lung tumors, which suggests the possibility of indirect effects of the methylation of miRNA genes on the level of expression of target genes.
The identification of
BRCA1/2
and
CHEK2
germline mutations is central to the molecular diagnostics of susceptibility to breast or/and ovarian cancer. A microarray-based rapid genotyping technique has ...been developed for identifying
BRCA1
(185delAG, 300T>G, 4153delA, 5382insC, and 4158 A>G, 5382insC),
BRCA2
(695insT and 6174delT), and
CHEK2
(1100delC) mutations. It was applied for 412 randomly collected breast-cancer specimens from central Russia. In 25 (6.0%) patients, breast cancer was associated with other tumors of, e.g., ovarian, cervical, or colorectal cancer.
BRCA1/2
and
CHEK2
mutations were detected in 33 breast-cancer patients (8.0%). The most frequent mutations were
BRCA1
5382insC, which was found in 16 patients (3.9%), and
CHEK2
1100delC, which was detected in seven patients (1.7%). The suggested diagnostic microarray proved to be an efficient means of identifying
BRCA1/2
and
CHEK2
founder mutations most frequent in central Russia and can be proposed as a high-throughput diagnostic tool for clinical genetic testing.
Familial adenomatous polyposis (FAP) and Peutz-Jeghers syndrome are genetic diseases characterized by gastrointestinal polyps, extraintestinal manifestations, and autosomal dominant inheritance. The ...carriers of these diseases from early childhood are at risk for neoplasias at different sites, which are symptomatic at various ages.
to study the clinical organ-specific manifestations in patients with FAP and Peutz-Jeghers, genetics update and possibilities of diagnosis, monitoring, and treatment of these diseases.
The authors give the results of their examination and follow-up of children with FAP and Peutz-Jeghers hamartoma-polypous syndrome. In addition, current data from PubMed, Medline (including reviews, original articles and case reports) were used.
The main clinical organ-specific signs of multiple tumors in FAP and Peutz-Jeghers syndrome are shown. Data on the assessment of a risk for malignant tumors at various sites in the affected patients and their family members at different ages are provided. Each of these syndromes has a dissimilar genetic foundation. FAP is caused by the germline mutations in the APC gene, Peutz-Jeghers syndrome is by the STK11 gene, which predispose individuals to specifically associated neoplasias and require different follow-up strategies. Information on a phenotype-genotype correlation may serve as a reference point for the possible severity and various manifestations of a disease. An update on the molecular pathogenesis of these diseases is considered.
Molecular genetic testing of the genes associated with FAP and Peutz-Jeghers syndromes makes it possible to timely recognize family members at high risk, to plan therapeutic strategy and to affect the course of a disease. The joint participation of pediatricians, proctologists, oncologists, morphologists, geneticists, and molecular biologists is essential to timely recognize the carriers of the syndromes and a better prognosis in these patients.
Tumor suppressor activity of
RASSF1A
in vitro and in vivo was established, in particular, in studies of knockout mice cells. Data on methylation of the promoter region and a lower expression of
...RASSF1A
were mostly obtained with cancer cell lines. Here, the
RASSF1A
mRNA was quantified the first time in primary epithelial malignant tumors of five various locations from 130 patients by semi-quantitative RT-PCR. Representative samples of kidney, lung, and breast carcinomas were examined. Preliminary data were obtained for
RASSF1A
expression in ovarian and colorectal carcinomas. System studies showed unexpected expression profiles, namely, the mRNA level increased (two- to sevenfold) more frequently than decreased in renal, breast, ovarian, and colorectal carcinomas. A higher
RASSF1A
mRNA level was significantly more frequent in renal cell carcinomas (24/38, 63% vs 8/38, 21%,
P
= 0.0004 by Fisher’s exact test) and ovarian carcinomas (8/13, 62% vs 2/13, 15%,
P
= 0.0114). Equal frequencies of lower and higher
RASSF1A
expression levels were only observed in non-small cell lung cancer (16/38, 42%). Noteworthy, an increase in expression was more common at early clinical stages of squamous cell lung cancer and adenocarcinoma, while a decrease in
RASSF1A
expression was more frequent at advanced clinical stages. In clear cell renal cell carcinoma, an increase in
RASSF1A
expression occurred more often at both early and advanced stages and was significant at advanced stages (
P
= 0.0094). The findings suggested tumor specificity for changes in
RASSF1A
expression. The observed regularities may also indicate that
RASSF1A
has dual functions in tumors, acting as a tumor suppressor and as a protooncogene.
Earlier, methylation of a CpG island in the SEMA3B gene (3p21.31) was observed in cell lines of small-cell and non-small-cell lung carcinoma. According to NCBI (Build 36), that island belonged to ...intron 1 of the gene. Our study concerns the methylation of two CpG islands, promoter and intronic, in the SEMA3B gene in patients with clear cell renal cell carcinoma (RCC). Methylation-specific PCR and bisulfite sequencing revealed a high frequency of methylation in the promoter CpG island (34/61, 56%) and somewhat lower, in the intronic (17/48, 35%). A significant inverse correlation was found between the SEMA3B mRNA level and methylation of the promoter CpG island in RCC (P < 0.05 according to Fisher's exact test). The intronic island showed no such correlation. Thus, we suggest that the methylation of the promoter CpG island contributes to the inactivation of the SEMA3B suppressor gene in RCC tissue.
MicroRNA regulates gene expression, is involved in many cellular processes, and plays an important role in the development of cancer. The regulation of the expression of miRNA genes can be achieved ...by methylating their CpG islands, which is shown in different types of tumors. The methylation of miRNA genes in clear cell renal cell carcinoma (CCRCC) has mainly been studied for the miR-9 and miR-34 families. The methylation of six miRNA genes (
miR-124a-2, -124a-3, -9-1, -9-3, -34b/c, -129-2
) was analyzed with using a representative sample (46 cases). Methylation of three genes
miR -124a-2
, -
124a-3
, and -
129-2
was studied in kidney tumors for the first time. Methylation analysis was performed using methyl specific PCR. It is shown that the frequency of methylation of six genes was changed from 37% to 65% in tumor samples and significantly higher in tumor samples than in samples of histologically normal tissue (
P
≤ 3 × 10
−5
by Fisher’s exact test). These results suggest the properties of tumor suppressors for the six miRNA genes indicated in CCRCC. We also found correlations between the methylation frequency of some miRNA genes and signs of the progression of CCRCC (tumor size, clinical stage, loss of differentiation, and metastasis).
Association of
TP53
Arg72Pro and
MDM2
T309G polymorphic markers with the risk of non-small-cell lung cancer was studied in a Russian population of the Moscow region. The minor Pro/Pro genotype of ...Arg72Pro and the TG genotype of T309G were associated with non-small-cell lung cancer (OR = 5.46,
p
= 8 × 10
−6
and OR = 7.38,
p
= 0.0001, respectively). Both Pro/Pro and TG genotypes were also strongly associated with lung adenocarcinoma (OR = 8.71,
p
= 3 × 10
−6
and OR = 8.13,
p
= 0.003, respectively) and squamous-cell lung carcinoma (OR = 4.2,
p
= 0.001 and OR = 7.02,
p
= 0.002, respectively). Finally, combined susceptible genotypes of
TP53
and
MDM2
polymorphisms Arg72Pro and T309G were reliably associated with non-small-cell lung cancer and both its subtypes (OR = 7.9,
p
= 0.01; OR = 9.12,
p
= 0.02; OR = 7.31,
p
= 0.03, respectively).
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