Elucidating the Underlying Functional Mechanisms of Breast Cancer Susceptibility Through Post-GWAS Analyses

Genome-wide association studies (GWAS) have identified more than 170 single nucleotide polymorphisms (SNPs) associated with the susceptibility to breast cancer. Together, these SNPs explain 18% of the familial relative risk, which is estimated to be nearly half of the total familial breast cancer risk that is collectively explained by low-risk susceptibility alleles. An important aspect of this success has been the access to large sample sizes through collaborative efforts within the Breast Cancer Association Consortium (BCAC), but also collaborations between cancer association consortia. Despite these achievements, however, understanding of each variant's underlying mechanism and how these SNPs predispose women to breast cancer remains limited and represents a major challenge in the field, particularly since the vast majority of the GWAS-identified SNPs are located in non-coding regions of the genome and are merely tags for the causal variants. In recent years, fine-scale mapping studies followed by functional evaluation of putative causal variants have begun to elucidate the biological function of several GWAS-identified variants. In this review, we discuss the findings and lessons learned from these post-GWAS analyses of 22 risk loci. Identifying the true causal variants underlying breast cancer susceptibility and their function not only provides better estimates of the explained familial relative risk thereby improving polygenetic risk scores (PRSs), it also increases our understanding of the biological mechanisms responsible for causing susceptibility to breast cancer. This will facilitate the identification of further breast cancer risk alleles and the development of preventive medicine for those women at increased risk for developing the disease

Elucidating the underlying functional mechanisms of breast cancer susceptibility through post-GWAS analyses

Genome-wide association studies (GWAS) have identified more than 170 single nucleotide polymorphisms (SNPs) associated with the susceptibility to breast cancer. Together, these SNPs explain 18% of the familial relative risk, which is estimated to be nearly half of the total familial breast cancer risk that is collectively explained by low-risk susceptibility alleles. An important aspect of this success has been the access to large sample sizes through collaborative efforts within the Breast Cancer Association Consortium (BCAC), but also collaborations between cancer association consortia. Despite these achievements, however, understanding of each variant's underlying mechanism and how these SNPs predispose women to breast cancer remains limited and represents a major challenge in the field, particularly since the vast majority of the GWAS-identified SNPs are located in non-coding regions of the genome and are merely tags for the causal variants. In recent years, fine-scale mapping studies followed by functional evaluation of putative causal variants have begun to elucidate the biological function of several GWAS-identified variants. In this review, we discuss the findings and lessons learned from these post-GWAS analyses of 22 risk loci. Identifying the true causal variants underlying breast cancer s

Evaluation of leishmanicidal effect of Euphorbia petiolata extract by in vivo anti-leishmanial assay using promastigotes of Leishmania major

Objective: The extract of different species of Euphorbia has been successfully used as a remedy for treatment of cutaneous leishmaniasis. The aim of this study was to assess the in vitro leishmanicidal effect of Euphorbia petiolata (E. petiolata) extract. Materials and Methods: Ethanolic percolated and methanolic Soxhlet extract of E. petiolata on promastigotes of L. major at different concentrations of extracts, one positive control group and one negative control group as well as 1 solvent control were prepared and placed in 24-well plates that contained 40,000 parasites/well. Afterwards, plates were incubated at 25 ˚C for six days and number of parasites in each well were determined on days 2, 4 and 6 of the experiment. Results: Both percolated and Soxhlet extracts in methanol and DMSO solvents had significant effects (equal to that of amphotericin B) on promastigote form of parasite at the concentration of 1 mg/ml. At lower concentrations, the extracts of E. petiolata had favorable leishmanicidal activity and killed L. major promastigotes dose-dependently. Conclusion: Our results support the possibility of E. petiolata extracts application as an anti-leishmanial agent with similar effects to amphotericin B

The Dilemma of TP53 Codon 72 Polymorphism (rs1042522) and Breast Cancer Risk : A Case-Control Study and Meta-Analysis in The Iranian Population

The authors would like to thank all participants in this research. We would also like to thank Mashhad University of Medical Sciences and Omid Hospital (Mashhad, Iran) for their support to the project. This work was financially supported by Mashhad University of Medical Sciences under Grant No. 930891. No potential conflict of interest was reported by the authors.Peer reviewedPublisher PD

Association of genetic polymorphisms of PON1 and CETP with the presence of metabolic syndrome; the effects of genotypes on their serum activity and concentrations

Peer reviewedPublisher PD

Association of heat shock protein70-2 (HSP70-2) gene polymorphism with obesity

Peer reviewedPublisher PD

TOX3 Gene polymorphisms and breast cancer; effects and implications of the variations: review article

Breast carcinoma is the most common cause of cancer mortality among women globally. Primary and secondary prevention through avoiding known risk factors, screening for early detection of tumors with different methods as well as timely treatment, can be effective in reduction of the burden of this devastating disease. This can in turn prevent death and also increase survival in patients with breast cancer. Both environmental and genetic factors are involved in the pathogenesis of breast cancer. Multiple genetic factors can influence the risk and development of breast cancer. Identification of genetic variants including single nucleotide polymorphisms (SNPs), which are associated with the risk of breast cancer development, are mostly done through genetic association studies. It is demonstrated that SNP allele frequencies vary amongst different populations. It has been shown that genetic risk factors like variations in TOX high mobility group box family member 3 (TOX3), which affect the liability for neoplasm, play an important role in the development of breast cancer. Although TOX3 is expressed mainly in the brain, its expression in other tissues especially breast has also been reported. TOX3 maps to chromosome 16q12 and encodes the nuclear high-mobility group (HMG)-box. It has calcium (Ca2+)-dependent transcriptional activities and is a co-factor of cAMP response element (CRE)-binding protein (CREB) and CREB-binding protein (CBP). TOX3, activated with Ca2+, is related with activation of the promoter of some other genes including BCL2 and C3 complement and also CITED1 gene expression. It also induces activation of the c-fos promoter and therefore its expression. Genome-wide association studies (GWAS) in different populations including European, Asian and African-American have demonstrated that a SNP near its 5ʹ end and the promoter of TOX3 gene appears to be significantly associated with breast cancer susceptibility. Furthermore, breast cancer–associated SNPs lead to enhanced FOXA1 bindings and in turn, a reduction in TOX3 gene expression. This review has highlighted the importance of TOX3 function, SNPs and its association with breast cancer risk and also its potential effects on breast cancer treatment; TOX3 plays dual and somehow conflicting roles in cancer initiation and progression which remains to be further investigated

Evaluating the association between ccr5delta32 polymorphism (Rs333) and the risk of breast cancer in a cohort of Iranian population

Funding Information: This manuscript was supported by the Student Research Committee of Mashhad University of science (Grant Numbers: 951734 & 961689).Peer reviewedPublisher PD

A Multiplex PCR-Based Next Generation Sequencing-Panel to Identify Mutations for Targeted Therapy in Breast Cancer Circulating Tumor Cells

Targeted therapy has become the preferred approach to treat most cancers, including metastatic breast cancer. Using liquid biopsies, which can act as a dynamic diagnostic tool, is an appealing concept to identify effective therapies. In order to identify mutations from circulating tumor cells (CTCs) on single cell level, we have developed a multiplex PCR-based next generation sequencing-panel. The CTCs were enriched using the CellSearch system and isolated by micromanipulation followed by whole genome amplification of their DNA. Afterwards, mutation hotspot regions in the PIK3CA, the ESR1, the AKT1, and the ERBB2 genes were amplified and barcoded. Sequencing was performed on a MiSeq system. The assay was validated with cells from various cell lines displaying the expected mutations. Mutations that provide the basis for potential targeted therapies were detected in 10 out of 13 patients in all analyzed genes. In four patients, mutations in more than one gene were observed—either in the same cell or in different cells, suggesting the presence of different tumor cell clones, which might be targeted with combination therapies. This assay is a time and cost effective tool to investigate the most relevant genomic positions indicative for targeted therapies in metastatic breast cancer. It can support therapy decision to improve the treatment of cancer patients

DanioCTC: Analysis of Circulating Tumor Cells from Metastatic Breast Cancer Patients in Zebrafish Xenografts

Circulating tumor cells (CTCs) serve as crucial metastatic precursor cells, but their study in animal models has been hindered by their low numbers. To address this challenge, we present DanioCTC, an innovative xenograft workflow that overcomes the scarcity of patient-derived CTCs in animal models. By combining diagnostic leukapheresis (DLA), the Parsortix microfluidic system, flow cytometry, and the CellCelector setup, DanioCTC effectively enriches and isolates CTCs from metastatic breast cancer (MBC) patients for injection into zebrafish embryos. Validation experiments confirmed that MDA-MB-231 cells, transplanted following the standard protocol, localized frequently in the head and blood-forming regions of the zebrafish host. Notably, when MDA-MB-231 cells spiked (i.e., supplemented) into DLA aliquots were processed using DanioCTC, the cell dissemination patterns remained consistent. Successful xenografting of CTCs from a MBC patient revealed their primary localization in the head and trunk regions of zebrafish embryos. DanioCTC represents a major step forward in the endeavors to study the dissemination of individual and rare patient-derived CTCs, thereby enhancing our understanding of metastatic breast cancer biology and facilitating the development of targeted interventions in MBC. Summary statement: DanioCTC is a novel workflow to inject patient-derived CTCs into zebrafish, enabling studies of the capacity of these rare tumor cells to induce metastases