Aberrant Methylation of 21 MicroRNA Genes in Breast Cancer: Sets of Genes Associated with Progression and a System of Markers for Predicting Metastasis

The Role of Methylation of a Group of microRNA Genes in the Pathogenesis of Metastatic Renal Cell Carcinoma

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.

Prediction of Distant Metastases in Patients with Kidney Cancer Based on Gene Expression and Methylation Analysis

Clear cell renal cell carcinoma (ccRCC) is the most common and aggressive histological type of cancer in this location. Distant metastases are present in approximately 30% of patients at the time of first examination. Therefore, the ability to predict the occurrence of metastases in patients at early stages of the disease is an urgent task aimed at personalized treatment. Samples of tumor and paired histologically normal kidney tissue from patients with metastatic and non-metastatic ccRCC were studied. Gene expression was analyzed using real-time PCR. The level of gene methylation was evaluated using bisulfite conversion followed by quantitative methylation-specific PCR. Two groups of genes were analyzed in this study. The first group includes genes whose expression is significantly reduced during metastasis: CA9, NDUFA4L2, EGLN3, and BHLHE41 (p < 0.001, ROC analysis). The second group includes microRNA genes: MIR125B-1, MIR137, MIR375, MIR193A, and MIR34B/C, whose increased methylation levels are associated with the development of distant metastases (p = 0.002 to <0.001, ROC analysis). Based on the data obtained, a combined panel of genes was formed to identify patients whose tumors have a high metastatic potential. The panel can estimate the probability of metastasis with an accuracy of up to 92%.

The Mechanism of DNA Methylation and miRNA in Breast Cancer

Breast cancer is the most prevalent cancer in the world. Currently, the main treatments for breast cancer are radiotherapy, chemotherapy, targeted therapy and surgery. The treatment measures for breast cancer depend on the molecular subtype. Thus, the exploration of the underlying molecular mechanisms and therapeutic targets for breast cancer remains a hotspot in research. In breast cancer, a high level of expression of DNMTs is highly correlated with poor prognosis, that is, the abnormal methylation of tumor suppressor genes usually promotes tumorigenesis and progression. MiRNAs, as non-coding RNAs, have been identified to play key roles in breast cancer. The aberrant methylation of miRNAs could lead to drug resistance during the aforementioned treatment. Therefore, the regulation of miRNA methylation might serve as a therapeutic target in breast cancer. In this paper, we reviewed studies on the regulatory mechanisms of miRNA and DNA methylation in breast cancer from the last decade, focusing on the promoter region of tumor suppressor miRNAs methylated by DNMTs and the highly expressed oncogenic miRNAs inhibited by DNMTs or activating TETs.

DNA methylation biomarkers accurately detect esophageal cancer prior and post neoadjuvant chemoradiation

BACKGROUND

Esophageal cancer (ECa) is associated with high mortality, mostly due to late diagnosis, precluding curativeintent surgery. Hence, neoadjuvant chemoradiation (ChRT) is recommended in most patients regardless of histological subtype. A proportion of these patients, however, achieve complete disease remission and might be spared of radical surgery. The lack of reliable, minimally invasive biomarkers able to detect post-ChRT disease persistence is, nonetheless, a major drawback. We have previously shown that miRNA promotor methylation enables accurate cancer detection in tissues and liquid biopsies but has been seldom explored in ECa patients.

AIMS

Herein, we sought to unveil and validate novel candidate biomarkers able to detect ECa prior and post ChRT.

MATERIALS AND METHODS

Promoter methylation of miR129-2, miR124-3 and ZNF569 was assessed, using quantitative methylation-specific PCR (qMSP), in tissue samples from normal esophagus, treatment-naïve and post-ChRT ECa, as well as in liquid biopsies from ECa patients.

RESULTS

All genes disclosed significantly different promoter methylation levels between ECa and normal esophagus, accurately detecting post-ChRT disease, especially for adenocarcinoma. Remarkably, miR129-2_me /ZNF569_me methylation panel identified ECa in liquid samples with 53% sensitivity and 87% specificity.

DISCUSSION

MiR129-2_me , miR124-3_me and ZNF569_me accurately discriminate ECa, either pre- or post-ChRT, from normal tissue, enabling ECa detection. Furthermore, circulalting methylation-based biomarkers are promising minimally invasive tools to detect post-ChRT residual ECa.

CONCLUSION

Overall, our results encourage the use of miRNA methylation biomarkers as accurate ECa detection tools as a novel approach for ChRT response monitoring.

Changes in the Level of Methylation of a Group of microRNA Genes as a Factor in the Development and Progression of Non-Small Cell Lung Cancer

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.

miRNAs in Cancer (Review of Literature)

MicroRNAs (miRNAs) are short, noncoding, single-stranded RNA molecules that regulate gene expression at the post-transcriptional level by binding to mRNAs. miRNAs affect the course of processes of fundamental importance for the proper functioning of the organism. These processes include cell division, proliferation, differentiation, cell apoptosis and the formation of blood vessels. Altered expression of individual miRNAs has been shown in numerous cancers, which may indicate the oncogenic or suppressor potential of the molecules in question. This paper discusses the current knowledge about the possibility of using miRNA as a diagnostic marker and a potential target in modern anticancer therapies.