Single nucleotide polymorphisms in DNA repair genes as risk factors associated to prostate cancer progression.

BACKGROUND: Besides serum levels of PSA, there is a lack of prostate cancer specific biomarkers. It is need to develop new biological markers associated with the tumor behavior which would be valuable to better individualize treatment. The aim of this study was to elucidate the relationship between single nucleotide polymorphisms (SNPs) in genes involved in DNA repair and prostate cancer progression. METHODS: A total of 494 prostate cancer patients from a Spanish multicenter study were genotyped for 10 SNPs in XRCC1, ERCC2, ERCC1, LIG4, ATM and TP53 genes. The SNP genotyping was made in a Biotrove OpenArray® NT Cycler. Clinical tumor stage, diagnostic PSA serum levels, and Gleason score at diagnosis were obtained for all participants. Genotypic and allelic frequencies were determined using the web-based environment SNPator. RESULTS: SNPs rs11615 (ERCC1) and rs17503908 (ATM) appeared as risk factors for prostate cancer aggressiveness. Patients wild homozygous for these SNPs (AA and TT, respectively) were at higher risk for developing cT2b - cT4 (OR = 2.21 (confidence interval (CI) 95% 1.47 - 3.31), p < 0.001) and Gleason scores ≥ 7 (OR = 2.22 (CI 95% 1.38 - 3.57), p < 0.001), respectively. Moreover, those patients wild homozygous for both SNPs had the greatest risk of presenting D'Amico high-risk tumors (OR = 2.57 (CI 95% 1.28 - 5.16)). CONCLUSIONS: Genetic variants at DNA repair genes are associated with prostate cancer progression, and would be taken into account when assessing the malignancy of prostate cancer.

High-throughput genotyping system as a robust and useful tool in oncology: experience from a single institution.

BACKGROUND AND AIM: Single nucleotide polymorphisms (SNPs) are substitutions of one base for another in the gene sequence and conforms the basis for pharmacogenetics and the development of personalized medicine. Many methods have been developed for SNP genotyping. The aim of the present study was to validate the use of a novel high-throughput genotyping system. METHODS: Five SNPs (rs25487, rs25489, rs1799782, rs13181, and rs11615) were genotyped in 118 cancer patients using the classical method PCR restriction fragment length polymorphism (RFLP) and the high-throughput, automated assay Biotrove OpenArray(®) NT Cycler, trying to explore the feasibility and reproducibility of the OpenArray system in the context of oncology. RESULTS: The call rates obtained ranged from 95.7 to 100% for both techniques. The percentage of overlapping ranged from 96.2 to 100% among both assays, showing a high reproducibility between the techniques. CONCLUSION: These findings, together with the low-cost and the simple and fast work flow, suggest that the OpenArray system is a robust and easy methodology for genotyping in the field of oncology.

Genetic variations in genes involved in testosterone metabolism are associated with prostate cancer progression: A Spanish multicenter study.

BACKGROUND: Prostate cancer (PCa) is an androgen-dependent disease. Nonetheless, the role of single nucleotide polymorphisms (SNPs) in genes encoding androgen metabolism remains an unexplored area. PURPOSE: To investigate the role of germline variations in cytochrome P450 17A1 (CYP17A1) and steroid-5α-reductase, α-polypeptides 1 and 2 (SRD5A1 and SRD5A2) genes in PCa. PATIENTS AND METHODS: In total, 494 consecutive Spanish patients diagnosed with nonmetastatic localized PCa were included in this multicenter study and were genotyped for 32 SNPs in SRD5A1, SRD5A2, and CYP17A1 genes using a Biotrove OpenArray NT Cycler. Clinical data were available. Genotypic and allelic frequencies, as well as haplotype analyses, were determined using the web-based environment SNPator. All additional statistical analyses comparing clinical data and SNPs were performed using PASW Statistics 15. RESULTS: The call rate obtained (determined as the percentage of successful determinations) was 97.3% of detection. A total of 2 SNPs in SRD5A1-rs3822430 and rs1691053-were associated with prostate-specific antigen level at diagnosis. Moreover, G carriers for both SNPs were at higher risk of presenting initial prostate-specific antigen levels>20ng/ml (Exp(B) = 2.812, 95% CI: 1.397-5.657, P = 0.004) than those who are AA-AA carriers. Haplotype analyses showed that patients with PCa nonhomozygous for the haplotype GCTTGTAGTA were at an elevated risk of presenting bigger clinical tumor size (Exp(B) = 3.823, 95% CI: 1.280-11.416, P = 0.016), and higher Gleason score (Exp(B) = 2.808, 95% CI: 1.134-6.953, P = 0.026). CONCLUSIONS: SNPs in SRD5A1 seem to affect the clinical characteristics of Spanish patients with PCa.

Polymorphisms in DNA-repair genes in a cohort of prostate cancer patients from different areas in Spain: heterogeneity between populations as a confounding factor in association studies.

BACKGROUND: Differences in the distribution of genotypes between individuals of the same ethnicity are an important confounder factor commonly undervalued in typical association studies conducted in radiogenomics. OBJECTIVE: To evaluate the genotypic distribution of SNPs in a wide set of Spanish prostate cancer patients for determine the homogeneity of the population and to disclose potential bias. DESIGN SETTING AND PARTICIPANTS: A total of 601 prostate cancer patients from Andalusia, Basque Country, Canary and Catalonia were genotyped for 10 SNPs located in 6 different genes associated to DNA repair: XRCC1 (rs25487, rs25489, rs1799782), ERCC2 (rs13181), ERCC1 (rs11615), LIG4 (rs1805388, rs1805386), ATM (rs17503908, rs1800057) and P53 (rs1042522). The SNP genotyping was made in a Biotrove OpenArray® NT Cycler. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Comparisons of genotypic and allelic frequencies among populations, as well as haplotype analyses were determined using the web-based environment SNPator. Principal component analysis was made using the SnpMatrix and XSnpMatrix classes and methods implemented as an R package. Non-supervised hierarchical cluster of SNP was made using MultiExperiment Viewer. RESULTS AND LIMITATIONS: We observed that genotype distribution of 4 out 10 SNPs was statistically different among the studied populations, showing the greatest differences between Andalusia and Catalonia. These observations were confirmed in cluster analysis, principal component analysis and in the differential distribution of haplotypes among the populations. Because tumor characteristics have not been taken into account, it is possible that some polymorphisms may influence tumor characteristics in the same way that it may pose a risk factor for other disease characteristics. CONCLUSION: Differences in distribution of genotypes within different populations of the same ethnicity could be an important confounding factor responsible for the lack of validation of SNPs associated with radiation-induced toxicity, especially when extensive meta-analysis with subjects from different countries are carried out.

Role of IGF-1 receptor in radiation response.

Insulin-like growth factor 1 receptor (IGF-1R) is a transmembrane receptor tyrosine kinase involved in the development and progression of cancer whose activation strongly promotes cell growth and survival. IGF-1R exerts its main actions through the activation of the mitogen-activated protein kinase and phosphoinositide 3-kinase pathways. In addition to their traditional roles, IGF-1R activation has been associated with increased radioresistance both in vitro and in vivo, although the molecular mechanisms behind this process are still unclear. Recently, IGF-1R has been associated to new partners as major vault proteins, BCL-2, BAX, or Ku70/80, related to radiochemotherapy resistance, regulation of apoptosis, and nonhomologous end-joining DNA repair. Here, we review these novel associations of IGF-1R trying to explain the resistance to radiotherapy mediated by IGF-1R. Finally, we revised the role of new therapies leading to block the receptor to enhance the efficacy of radiation.