The RAD51 135G>C polymorphism is related to the effect of adjuvant therapy in early breast cancer

Single nucleotide polymorphisms as the efficient prognostic markers in breast cancer

BACKGROUND

Breast cancer (BC) is known as the most common malignancy in women. Environmental and genetic factors are associated with BC progression. Genetic polymorphisms have been reported as important risk factors of BC prognosis and drug response. Main body: Therefore, in the present review, we have summarized all single nucleotide polymorphisms (SNPs) which have been significantly associated with drug response in BC patients around the world. We have also categorized the reported SNPs based on their related genes functions to clarify the molecular biology of drug responses in BC.

CONCLUSION

The majority of SNPs were reported in detoxifying enzymes, which introduced such genes as the main genetic risk factors during BC drug responses. This review paves the way for introducing a prognostic panel of SNPs for the BC patients in the world.

Model-Based Integration Analysis Revealed Presence of Novel Prognostic miRNA Targets and Important Cancer Driver Genes in Triple-Negative Breast Cancers

Background: miRNAs (microRNAs) play a key role in triple-negative breast cancer (TNBC) progression, and its heterogeneity at the expression, pathological and clinical levels. Stratification of breast cancer subtypes on the basis of genomics and transcriptomics profiling, along with the known biomarkers’ receptor status, has revealed the existence of subgroups known to have diverse clinical outcomes. Recently, several studies have analysed expression profiles of matched mRNA and miRNA to investigate the underlying heterogeneity of TNBC and the potential role of miRNA as a biomarker within cancers. However, the miRNA-mRNA regulatory network within TNBC has yet to be understood. Results and Findings: We performed model-based integrated analysis of miRNA and mRNA expression profiles on breast cancer, primarily focusing on triple-negative, to identify subtype-specific signatures involved in oncogenic pathways and their potential role in patient survival outcome. Using univariate and multivariate Cox analysis, we identified 25 unique miRNAs associated with the prognosis of overall survival (OS) and distant metastases-free survival (DMFS) with “risky” and “protective” outcomes. The association of these prognostic miRNAs with subtype-specific mRNA genes was established to investigate their potential regulatory role in the canonical pathways using anti-correlation analysis. The analysis showed that miRNAs contribute to the positive regulation of known breast cancer driver genes as well as the activation of respective oncogenic pathway during disease formation. Further analysis on the “risk associated” miRNAs group revealed significant regulation of critical pathways such as cell growth, voltage-gated ion channel function, ion transport and cell-to-cell signalling. Conclusion: The study findings provide new insights into the potential role of miRNAs in TNBC disease progression through the activation of key oncogenic pathways. The results showed previously unreported subtype-specific prognostic miRNAs associated with clinical outcome that may be used for further clinical evaluation.

Role of Rad51 and DNA repair in cancer: A molecular perspective

The maintenance of genome integrity is essential for any organism survival and for the inheritance of traits to offspring. To the purpose, cells have developed a complex DNA repair system to defend the genetic information against both endogenous and exogenous sources of damage. Accordingly, multiple repair pathways can be aroused from the diverse forms of DNA lesions, which can be effective per se or via crosstalk with others to complete the whole DNA repair process. Deficiencies in DNA healing resulting in faulty repair and/or prolonged DNA damage can lead to genes mutations, chromosome rearrangements, genomic instability, and finally carcinogenesis and/or cancer progression. Although it might seem paradoxical, at the same time such defects in DNA repair pathways may have therapeutic implications for potential clinical practice. Here we provide an overview of the main DNA repair pathways, with special focus on the role played by homologous repair and the RAD51 recombinase protein in the cellular DNA damage response. We next discuss the recombinase structure and function per se and in combination with all its principal mediators and regulators. Finally, we conclude with an analysis of the manifold roles that RAD51 plays in carcinogenesis, cancer progression and anticancer drug resistance, and conclude this work with a survey of the most promising therapeutic strategies aimed at targeting RAD51 in experimental oncology.

RAD51 and XRCC3 Polymorphisms Are Associated with Increased Risk of Prostate Cancer

Genetic polymorphisms in DNA repair genes may affect DNA repair efficiency and may contribute to the risk of developing cancer. The aim of our study was to investigate single nucleotide polymorphisms (SNPs) in RAD51 (rs2619679, rs2928140, and rs5030789) and XRCC3 (rs1799796) involved in DNA double-strand break repair and their relationship to prostate cancer. The study group included 99 men diagnosed with prostate cancer and 205 cancer-free controls. SNP genotyping was performed using the PCR-RFLP method. A significant association was detected between RAD51 rs5030789 polymorphism and XRCC3 rs1799796 polymorphism and an increased risk of prostate cancer. Our results indicate that RAD51 and XRCC3 polymorphism may contribute to prostate cancer.

Breast cancer genetics in young women: What do we know?

Breast cancer (BC) in young women, generally defined in oncology as women who are 40 years of age or younger, represents 2 out of 10 BC cases in developing countries. Several research studies, including genetic cancer panel tests, genome-wide association studies, expression analyses and polymorphisms reports, have found that young women with BC exhibit a higher genetic susceptibility and specific genomic signature compared to postmenopausal women with BC. Thus, international guidelines recommend genetic counseling for this age population. This review presents the current state of the art of genetics and genomics with regards to young women with BC.

RAD51 as a potential surrogate marker for DNA repair capacity in solid malignancies

Targeting deficient mechanisms of cellular DNA repair still represents the basis for the treatment of the majority of solid tumors, and increased DNA repair capacity is a hallmark mechanism of resistance not only to DNA-damaging treatments such as cytotoxic drugs and radiotherapy, but also to small molecule targeted drugs such as inhibitors of poly-ADP ribose polymerase (PARP). Hence, there is substantial medical need for potent and convenient biomarkers of individual response to DNA-targeted treatment in personalized cancer care. RAD51 is a highly conserved protein that catalyzes DNA repair via homologous recombination, a major DNA repair pathway which directly modulates cellular sensitivity to DNA-damaging treatments. The clinical and biological significance of RAD51 protein expression is still under investigation. Pre-clinical studies consistently show the important role of nuclear RAD51 immunoreactivity in chemo- and radioresistance. Validating data from clinical trials however is limited at present, and some clinical studies show controversial results. This review gives a comprehensive overview on the current knowledge about the prognostic and predictive value of RAD51 protein expression and genetic variability in patients with solid malignancies.

Interleukin-16 polymorphisms as new promising biomarkers for risk of gastric cancer

Gastric cancer (GC) is the second cause of cancer-related death worldwide. Interleukin (IL)-16 has a vital role in the development and homeostasis of the immune system. In the present study, we evaluated an exon variant rs4072111 C/T polymorphism and 3' UTR variant rs1131445 C/T within the miRNA binding with gastric cancer susceptibility in Iranian population. Genomic DNA was isolated from peripheral blood samples according to phenol chloroform extraction. The genotypes of IL-16 polymorphisms rs1131445 T/C and rs4072111 T/C were determined by polymerase chain reaction-restriction fragment length polymorphism method. In this case control study, a total of 256 patients with gastric cancer (238 cases (92.9 %) non-cardia and 18 cases (7.1 %) cardia) and 300 healthy control subjects were evaluated. In the present study, we found a significant association between rs4072111 of IL-16 gene and risk of GC in Iranian population. Individuals with CT genotype showed a significant association with 1.79-fold increased risk of GC (P = 0.008; adjusted OR 1.792; 95 % CI 1.164-2.759). The significant association was also detected for T allele of rs4072111 and increased risk of GC (P < 0.001; adjusted OR 1.981; 95 % CI 1.354-2.900). We also observed statistically a significant relationship between rs1131445 of IL-16 CT genotype and GC risk. Carriers of IL-16 CT genotype compared with TT genotype had 1.44 times higher increased likelihood of GC (P = 0.048; adjusted OR 1.445; 95 % CI 1.003-2.084). After stratification according to gender, we observed that in rs1131445, CT and CC male carriers had a higher risk of GC than females (P = 0.08; adjusted OR 1.608; 95 % CI 0.945-2.737 and P = 0.08; adjusted OR 2.186; 95 % CI 0.897-5.325, respectively). We also observed that for male carriers with C allele in rs1131445, there was a 1.53-fold higher risk of GC risk than female subjects (P = 0.029; adjusted OR 1.53; 95 % CI 1.04.4-2.248). We found that the rs1131445 T/C and rs4072111 T/C variants of IL-16 were significantly associated with increased risk of GC in Iranian population.