| Summary: | 碩士 === 高雄醫學大學 === 醫學研究所碩士班 === 93 === HER2 plays a major role in breast cancer. Several recent epidemiological studies demonstrated that there was a single missense point mutation at codon 655 of HER2 and this might be associated with breast cancer. Therefore, the aim of this study was to investigate the HER2 I655V genotyping in a case-control study of breast cancer at Kaohsiung in Taiwan. We analyzed the genomic DNA I655V polymorphism with a PCR-RFLP assay in 424 patients with breast cancer and 395 controls. In addition, we also evaluated the relationships of the HER2 genotype to the HER2 protein expression, hormone receptors, and tumor stages in patients with breast cancer. The results showed that the frequencies of the Ile/Ile and Val carrier genotype were 80.4% and 19.6%, respectively, in patients with breast cancer and 86.3% and 13.7%, respectively, in the controls. The patients were classified into two groups according to whether they were defined as patients with an early-onset breast cancer, which is by 45 years of age. After analysis, we found that patients who were younger than 45 years of age had a higher frequency of the Val carrier compared with those over 45 years of age. There were no correlations between the HER2 I655V genotype and either of HER2 and hormone receptor protein status and tumor stages in patients with breast cancer. We conclude that the HER2 I655V genotype especially with a Val carrier plays a strong role in breast cancer at a younger age.
Routinely the IHC method is the most frequently used for the detection of the HER2 gene expression at the protein level, however, the IHC method is more time-consuming and it must be precisely quantified. Therefore, we compared the IHC method with two relative real-time PCR methods to assess the gene expression of HER2. The first method (method A) is based on the external standard curve to calculate the ratio of the copy number of the target gene (HER2) and, that of the reference gene (TBP) in each human breast tumor and adjacent normal tissue (the ratio termed “N1”). The second method (method B) is based on the efficiencies and the Cp deviation of each human breast tumor versus the compared adjacent normal tissue, and then it is expressed in comparison with the reference gene (the ratio termed “N2”). After statistical analysis, we found that the patients with HER2 overexpression in the method B analysis were highly associated with advanced-stage breast cancer. We conclude that method B is very useful for use in the identification of the HER2 gene expression for breast cancer, especially stage III of AJCC.
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