Loss of Heterozygosity in Thyroid Hormone Receptor Beta in Invasive Breast Cancer

Epigenetic-Mediated Regulation of Gene Expression for Biological Control and Cancer: Cell and Tissue Structure, Function, and Phenotype

Epigenetic gene regulatory mechanisms play a central role in the biological control of cell and tissue structure, function, and phenotype. Identification of epigenetic dysregulation in cancer provides mechanistic into tumor initiation and progression and may prove valuable for a variety of clinical applications. We present an overview of epigenetically driven mechanisms that are obligatory for physiological regulation and parameters of epigenetic control that are modified in tumor cells. The interrelationship between nuclear structure and function is not mutually exclusive but synergistic. We explore concepts influencing the maintenance of chromatin structures, including phase separation, recognition signals, factors that mediate enhancer-promoter looping, and insulation and how these are altered during the cell cycle and in cancer. Understanding how these processes are altered in cancer provides a potential for advancing capabilities for the diagnosis and identification of novel therapeutic targets.

Detection of Loss of Heterozygosity (LOH) Using Circulating Cell-free DNA (cfDNA) by Fluorescence-based Multiplex PCR for Identification of Patients With Prostate Cancer

Several lines of evidence suggest that loss of heterozygosity (LOH) in specific chromosomal regions is a common mechanism for the inactivation of tumor-suppressor genes that are implicated in the pathogenesis of prostate cancer (PCa). Short tandem repeat (STR) sequences are extremely reliable genetic markers for the detection of LOH associated with cancers. Hence, in the current study, we investigated the detection of LOH at 6 STR markers (D8S360, D9S1748, D9S171, D8S137, D6S1631, and THRB) using blood circulating cell-free DNA (cfDNA), which can be used to distinguish PCa from benign prostatic hyperplasia (BPH). A total of 136 individuals were included in the study, 76 male patients diagnosed with PCa (50 male patients with localized PCa and 26 male patients with metastatic PCa) as experimental subjects and 60 male patients with BPH as controls. Circulating cfDNA was extracted from plasma samples and amplified with fluorescence-labeled primers specific for known STR markers. We also evaluated the serum prostate-specific antigen in both groups. Our findings revealed that the frequency of LOH at D8S360, D9S1748, D9S171, D8S137, and D6S1631 was significantly higher in PCa subjects than in controls (P<0.05). Of the 6 STR markers, LOH at D8S360 could discriminate metastatic PCa from localized PCa. We found that 71.05% of patients with PCa and 1.66% of BPH subjects had LOH at least at 3 of the markers in cfDNA. Our findings provide additional evidence to support the hypothesis that analysis of LOH at D8S360, D9S1748, D9S171, D8S137, and D6S1631 STR markers using cfDNA can be applied as a noninvasive diagnostic approach for the detection of PCa.

Higher order genomic organization and epigenetic control maintain cellular identity and prevent breast cancer

Cells establish and sustain structural and functional integrity of the genome to support cellular identity and prevent malignant transformation. In this review, we present a strategic overview of epigenetic regulatory mechanisms including histone modifications and higher order chromatin organization (HCO) that are perturbed in breast cancer onset and progression. Implications for dysfunctions that occur in hormone regulation, cell cycle control, and mitotic bookmarking in breast cancer are considered, with an emphasis on epithelial-to-mesenchymal transition and cancer stem cell activities. The architectural organization of regulatory machinery is addressed within the contexts of translating cancer-compromised genomic organization to advances in breast cancer risk assessment, diagnosis, prognosis, and identification of novel therapeutic targets with high specificity and minimal off target effects.

Investigating the association of rs2910164 with cancer predisposition in an Irish cohort

INTRODUCTION

MicroRNAs (miRNAs) are small noncoding RNA molecules that exert post-transcriptional effects on gene expression by binding with cis-regulatory regions in target messenger RNA (mRNA). Polymorphisms in genes encoding miRNAs or in miRNA-mRNA binding sites confer deleterious epigenetic effects on cancer risk. miR-146a has a role in inflammation and may have a role as a tumour suppressor. The polymorphism rs2910164 in the MIR146A gene encoding pre-miR-146a has been implicated in several inflammatory pathologies, including cancers of the breast and thyroid, although evidence for the associations has been conflicting in different populations. We aimed to further investigate the association of this variant with these two cancers in an Irish cohort.

METHODS

The study group comprised patients with breast cancer (BC), patients with differentiated thyroid cancer (DTC) and unaffected controls. Germline DNA was extracted from blood or from saliva collected using the DNA Genotek Oragene 575 collection kit, using crystallisation precipitation, and genotyped using TaqMan-based PCR. Data were analysed using SPSS, v22.

RESULTS

The total study group included 1516 participants. This comprised 1386 Irish participants; 724 unaffected individuals (controls), 523 patients with breast cancer (BC), 136 patients with differentiated thyroid cancer (DTC) and three patients with dual primary breast and thyroid cancer. An additional cohort of 130 patients with DTC from the South of France was also genotyped for the variant. The variant was detected with a minor allele frequency (MAF) of 0.19 in controls, 0.22 in BC and 0.27 and 0.26 in DTC cases from Ireland and France, respectively. The variant was not significantly associated with BC (per allele odds ratio = 1.20 (0.98-1.46), P  = 0.07), but was associated with DTC in Irish patients (per allele OR = 1.59 (1.18-2.14), P = 0.002).

CONCLUSION

The rs2910164 variant in MIR146A is significantly associated with DTC, but is not significantly associated with BC in this cohort.