Association of HER2 codon 655 polymorphism with ovarian cancer.

The role of the human epidermal growth factor receptor 2 (HER2) codon 655 (Ile655Val) polymorphism in ovarian cancer is not fully understood. Two studies indicated a possible association between the Val allele and elevated risk or reduced prognosis of ovarian cancer. We investigated the HER2 codon 655 (rs1136201) polymorphism in 242 Austrian women-142 ovarian cancer patients and 100 healthy controls-by polymerase chain reaction and pyrosequencing. Associations between Ile655Val polymorphism and clinicopathological variables (e.g., age, FIGO stage, grading, serous vs. non-serous histology) were evaluated. The genotype distributions in ovarian cancer patients and controls were: AA; 66.2 %, AG; 25.35 %, GG; 8.45 %, and AA; 63 %, AG; 34 %, GG; 3.7 %, respectively (OR 1.15, CI 95 % 0.67-1.96). We observed a non-significant trend toward elevated cancer risk in Val/Val genotype (OR 2.98, CI 95 % 0.82-10.87, p = 0.10). Of note, 11 out of 12 Val/Val homozygotes were postmenopausal. The link between the Val/Val homozygosity and age over 50 years at diagnosis (OR 0.15, CI 95 % 0.02-1.2) was barely significant (p = 0.056). Summarizing, our data indicated a non-significant trend toward increased ovarian cancer risk in the Val/Val homozygosity, especially in women aged above 50 years. Further large-cohort studies focusing on the role of the HER2 codon 655 Val allele are needed.

HER2Ile655Val Single Nucleotide Polymorphism Associated with Early-Onset Breast Cancer Susceptibility: A Systematic Review and Meta-Analysis.

ackground: Human epidermal growth factor receptor 2 (HER2) plays an important role in the development and progression of breast cancer. To understand the precise association, this meta-analysis was conducted to estimate the association between HER2Ile655Val single nucleotide polymorphism (SNP) and susceptibility to early-onset breast cancer. METHODS: A comprehensive database retrieval from PubMed, Embase, Web of Science and Google Scholar was pooled to investigate links between the HER2Ile655Val SNP and risk of breast cancer. Adjusted odds ratios (ORs) with 95% confidence intervals (CIs) were estimated to appraise the association under the additive model (Ile vs. Val), dominant model (Val/Val + Ile/Val vs. Ile/Ile), and recessive model (Val/Val vs. Ile/Val + Ile/Ile). RESULTS: Seventeen relevant studies with 11,749 cases and 8,105 controls were finally included. We found that HER2Ile655Val SNP is associated with an increased risk of breast cancer in an additive and dominant model. In the subgroup analysis with age stratification, a significant association between the HER2 codon 655 SNP and the risk of breast cancer was found in young women in an additive, dominant, and recessive model; conversely, no significant associations were indicated in older women. In the breast cancer subgroup, HER2Ile655Val SNP was significantly associated with younger age women with breast cancer in the dominant model. In contrast, no association between the HER2 codon 655 SNP and age was found in control populations. CONCLUSION: Our findings suggest that the Val allele in HER2 codon 655 SNP is strongly associated with breast cancer susceptibility in the young female population and is also significantly associated with younger age in women with breast cancer. HER2Ile655Val SNP might be a susceptibility factor that favours early-onset breast cancer.
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Design and characterization of a SYBR Green I-based melting curve method for investigation of HER2I655V polymorphism in breast cancer.

BACKGROUND: Breast cancer is a disease in which cell grows rapidly forming a mass in the breast. HER2 polymorphisms Ile655Val have been studied as biomarkers for breast cancer and may comprise a risk factor of cardiac toxicity for breast cancer-consuming trastuzumab. AIM OF WORK: In this study, we developed a simple, low cost, and rapid test to detect polymorphism at HER2 gene using SYBR Green I-based melting curve method. SUBJECTS AND METHODS: In this report, we performed allelic discrimination with real-time temperature melting (Tm) Shift SYBR Green I-based melting curve method. The melting profiles of amplified DNA HER-2 Ile655Val and its characteristics were analyzed. RESULT: Tm value of HER2 GG and AA alleles were 85 ± 0.14 °C and 82.5 ± 0.23 °C, respectively, while cycle threshold (Ct) value of GG, AG, and AA alleles were 19.6 ± 0.27, 22.5 ± 0.23, 18.6 ± 0.22 correspondingly; furthermore, no template control has shown consisting Ct value at 31.18 ± 0.27. The developed methods' characteristics were optimum annealing at 62 °C and Kappa coefficient value 1 with the mean almost consistent with PCR-sequencing. The coefficient of variability for intra-assay of GG, AG, and AA was in the range of 0.2-1%, while the coefficient of variability for inter-assay for each were in the range 0.7-1%. Further, based on PCR, shelf-life assay has shown stability for 3 months of storage observation. CONCLUSION: This approach may be considered as simple, rapid, and low cost supporting the rapid study of HER2 epidemiology. Furthermore, the developed methods potentially facilitate clinicians in dealing with breast cancer patients, especially in considering about the cardiotoxicity effect of trastuzumab.

Modified allele-specific PCR improves HER2 Ile655Val detection by reducing genotyping errors

Background: A reliable method to detect gene polymorphisms must be established to eliminate genotyping errors due to false PCR amplification. In the previous study, we have developed AS-PCR (Allele Specific-Polymerase Chain Reaction) to detect HER2 Ile655Val gene polymorphism with good specificity and sensitivity, yet it produces some errors. This study is aimed to eliminate the source of genotyping errors mainly by betaine treatment and PCR program modification. Methods: Genotyping errors produced by AS-PCR was qualitatively and quantitatively evaluated using two genomic DNA that each contained AA genotype and GG genotype of HER2 Gene. Betaine treatment or PCR program modification was tested to eliminate the occurrence of genotyping errors during AS-PCR amplification. Results: The types of genotyping errors exhibited by HER2 Ile655Val AS-PCR are diverse, ranging from LDO (Locus Drop Out), preferential amplification to ADO (Allele Drop Out). The rate of genotyping errors was from 10% to 50% depending on the amount and ratio of DNA template and the annealing temperature of PCR. In the mixed DNA template model, the betaine treatment has shown to reduce ADO only in preferentially amplified GG genotype amplicon. Alternatively, reducing the template of the heterozygous DNA by half ( -0.5 ng of DNA template) for such case has effectively recovered the AS-PCR from ADO. Furthermore, increasing the denaturation temperature to 96 °C with an annealing time of 40 s at the first 10 cycles of AS-PCR has succeeded in eliminating severe preferential amplification of AA genotype amplicon by preventing the DNA template with GG genotype from forming into a G-quadruplex structure. The guideline offered in this study has been successfully applied for clinical samples of breast cancer that show preferential amplification. Conclusion: Betaine and the modifying AS-PCR program can reduce significantly genotyping errors making AS-PCR for HER2 Ile655Val detection more reliable to be used as a molecular tool for genotyping purpose (AU)