DNA methylation biomarkers for noninvasive detection of triple-negative breast cancer using liquid biopsy.

Noninvasive detection of aberrant DNA methylation could provide invaluable biomarkers for earlier detection of triple-negative breast cancer (TNBC) which could help clinicians with easier and more efficient treatment options. We evaluated genome-wide DNA methylation data derived from TNBC and normal breast tissues, peripheral blood of TNBC cases and controls and reference samples of sorted blood and mammary cells. Differentially methylated regions (DMRs) between TNBC and normal breast tissues were stringently selected, verified and externally validated. A machine-learning algorithm was applied to select the top DMRs, which then were evaluated on plasma-derived circulating cell-free DNA (cfDNA) samples of TNBC patients and healthy controls. We identified 23 DMRs accounting for the methylation profile of blood cells and reference mammary cells and then selected six top DMRs for cfDNA analysis. We quantified un-/methylated copies of these DMRs by droplet digital PCR analysis in a plasma test set from TNBC patients and healthy controls and confirmed our findings obtained on tissues. Differential cfDNA methylation was confirmed in an independent validation set of plasma samples. A methylation score combining signatures of the top three DMRs overlapping with the SPAG6, LINC10606 and TBCD/ZNF750 genes had the best capability to discriminate TNBC patients from controls (AUC = 0.78 in the test set and AUC = 0.74 in validation set). Our findings demonstrate the usefulness of cfDNA-based methylation signatures as noninvasive liquid biopsy markers for the diagnosis of TNBC.

Epigenetic quantification of circulating immune cells in peripheral blood of triple-negative breast cancer patients.

BACKGROUND: A shift in the proportions of blood immune cells is a hallmark of cancer development. Here, we investigated whether methylation-derived immune cell type ratios and methylation-derived neutrophil-to-lymphocyte ratios (mdNLRs) are associated with triple-negative breast cancer (TNBC). METHODS: Leukocyte subtype-specific unmethylated/methylated CpG sites were selected, and methylation levels at these sites were used as proxies for immune cell type proportions and mdNLR estimation in 231 TNBC cases and 231 age-matched controls. Data were validated using the Houseman deconvolution method. Additionally, the natural killer (NK) cell ratio was measured in a prospective sample set of 146 TNBC cases and 146 age-matched controls. RESULTS: The mdNLRs were higher in TNBC cases compared with controls and associated with TNBC (odds ratio (OR) range (2.66-4.29), all Padj. < 1e-04). A higher neutrophil ratio and lower ratios of NK cells, CD4 + T cells, CD8 + T cells, monocytes, and B cells were associated with TNBC. The strongest association was observed with decreased NK cell ratio (OR range (1.28-1.42), all Padj. < 1e-04). The NK cell ratio was also significantly lower in pre-diagnostic samples of TNBC cases compared with controls (P = 0.019). CONCLUSION: This immunomethylomic study shows that a shift in the ratios/proportions of leukocyte subtypes is associated with TNBC, with decreased NK cell showing the strongest association. These findings improve our knowledge of the role of the immune system in TNBC and point to the possibility of using NK cell level as a non-invasive molecular marker for TNBC risk assessment, early detection, and prevention.

DNA methylation of the long intergenic noncoding RNA 299 gene in triple-negative breast cancer: results from a prospective study.

Triple-negative breast cancer (TNBC) is an aggressive breast cancer subtype associated with a high rate of recurrence and poor prognosis. Recently we identified a hypermethylation in the long noncoding RNA 299 (LINC00299) gene in blood-derived DNA from TNBC patients compared with healthy controls implying that LINC00299 hypermethylation may serve as a circulating biomarker for TNBC. In the present study, we investigated whether LINC00299 methylation is associated with TNBC in a prospective nested breast cancer case-control study within the Generations Study. Methylation at cg06588802 in LINC00299 was measured in 154 TNBC cases and 159 breast cancer-free matched controls using MethyLight droplet digital PCR. To assess the association between methylation level and TNBC risk, logistic regression was used to calculate odd ratios and 95% confidence intervals, adjusted for smoking status. We found no evidence for association between methylation levels and TNBC overall (P = 0.062). Subgroup analysis according to age at diagnosis and age at blood draw revealed increased methylation levels in TNBC cases compared with controls in the young age groups [age 26-52 (P = 0.0025) and age 22-46 (P = 0.001), respectively]. Our results suggest a potential association of LINC00299 hypermethylation with TNBC in young women.

Promoter hypermethylation and downregulation of the FAS gene may be involved in colorectal carcinogenesis.

Aberrant DNA methylation has been investigated in carcinogenesis and as biomarker for the early detection of colorectal cancer (CRC). The present study aimed to define the methylation status in the regulatory elements of two proapoptotic genes, Fas cell surface death receptor (FAS) and BCL2-associated X protein (BAX). DNA methylation analysis was performed in tumor and adjacent normal tissue using HpaII/MspI restriction digestion and methylation-specific polymerase chain reaction (PCR). The results observed downregulation of the FAS and BAX genes in the CRC tissues compared with the adjacent normal samples. Furthermore, demethylation using 5-aza-2'-deoxycytidine treatment followed by reverse-transcription quantitative PCR were performed on the HT-29 cell line to measure BAX and FAS mRNA expression following demethylation. The 5-aza-2'-deoxycytidine treatment resulted in significant FAS gene upregulation in the HT-29 cell line, but no significant difference in BAX expression. Furthermore, analysis of CpG islands in the FAS gene promoter revealed that the FAS promoter was significantly hypermethylated in 53.3% of tumor tissues compared with adjacent normal samples. Taken together, the results indicate that decreased expression of the FAS gene due to hypermethylation of its promoter may lead to apoptotic resistance, and acts as an important step during colorectal carcinogenesis.

Downregulation of external death receptor genes FAS and DR5 in colorectal cancer samples positive for human papillomavirus infection.

AIM: Human papillomaviruses (HPV) have frequently been detected in colorectal cancer tumor samples, and may play a role in the pathogenesis of colorectal cancer. This study was designed to investigate the presence of DNA and RNA for the high-risk HPV genotypes 16 and 18 in samples of colorectal cancer tumors and adjacent normal tissues. We also investigated the expression of proapoptotic genes in HPV-positive colorectal tumors compared to normal tissue samples. METHODS: Samples of tumoral and adjacent normal tissues were fresh-frozen, and HPV DNA was identified by nested and semiquantitative PCR. Real time PCR was used to quantitatively compare the expression of HPV-18 E6 and nine proapoptotic genes in HPV-positive tumors and samples of adjacent normal tissue. RESULTS: HPV-16 DNA was found in 10.5% of the tumor samples, and HPV-18 DNA was found in 23.6% of the samples. Real time PCR results showed lower expression of the E6 gene in HPV-positive tumors than in adjacent normal tissue. The expression of two proapoptotic genes, FAS and DR5, was significantly lower in tumor samples than in adjacent normal tissues. CONCLUSIONS: HPV infection, especially HPV-18, may play a role in colorectal cancer tumorigenesis by downregulating death receptor genes and interfering with the extrinsic pathway of apoptosis.

Effects of extremely low-frequency electromagnetic field on fertility and heights of epithelial cells in pre-implantation stage endometrium and fallopian tube in mice.

OBJECTIVE: To investigate the effects of extremely low-frequency electromagnetic field (ELF-EMF) on fertility and heights of epithelial cells in pre-implantation stage endometrium and fallopian tube in mice. METHODS: Eighty female NMRI mice were randomly divided into 2 groups: control group was not exposed to EMF and experimental group was exposed to 4-hour EMF per day, 6 days a week for 2 weeks to 50 Hz, 0.5 mT EMF. Female mice in two groups were superovulated and mated with male mice over night. At the time of implantation, the blastocysts were obtained from the presumed pregnant mice with vaginal plug by flushing the uterus horns. The samples of uterus horns and fallopian tubes in two groups were taken and were processed for light microscopic studies. RESULTS: The analysis of mean number of the flushed blastocysts in the EMF group showed significant decrease as compared with the control group (P<0.03). Light microscopic study showed that the height of fallopian tube epithelial cells was significantly increased in the EMF group as compared with the control group (P<0.001). However the height of endometrial epithelial cells in the EMF group showed insignificant increase as compared with the control group. CONCLUSION: The results indicate that ELF-EMF has detrimental effect on female reproductive system in mice by decreasing the number of flushed blastocysts and increasing the height of fallopian tube epithelial cells.