Detecting HER-2/NEU gene polymorphism with PCR-RFLP method on the paraffin tissue section of breast cancer cases

Breast cancer is the most common type of cancer in women being the second common cause of cancer related deaths. Breast cancer occurs as a result of multistep carcinogenesis affecting important cellular pathways acting role in cellular growth and development. The most important prognoctic factors in routine practice are lympth node metastasis, tumor size, histological grade and type. Steroid hormone receptor status and molecular markers are other important prognostic factor. HER-2/neu is a proto-oncogene encoding a transmembrane glycoprotein (p185) with a tyrosine kinase activity, Her-2/neu amplification and/or overexpression has been releated with poor prognosis, at chromosome region 17q21. This protein is a member of the epidermal growth factor receptor family. Amplification and/or overexpression of HER-2/neu has been reported to be associated with poor prognosis. One single-nucleotide polymorphism (SNP) at codon 655 indicates a guanine-to-adenine substitution (Ile655Val) in the transmembrane domain-coding region of the HER2 gene. This single nucleotide polymorphism (SNP) of HER-2/neu gene at codon 655 (rs1136201), encoding either isoleucine (Ile: ATC) or valine (Val: GTC), has been identified. It has been reported that this Ile/Val SNP is associated with increased risk of breast cancer. However, several studies have shown that this association is controversial.In this study, we analyzed the HER2 codon 655 polymorphisms in parafin block sections from 58 breast cancer patients and 55 control subjects and evaluated the association of the polymorphic alleles with breast cancer. PCR-RFLP (Polymerase Chain Reaction-Restriction Fragment Length Polymorphism) method was carried out, following DNA isolation. The frequency of the polymorphic Val allele was detected 12.1% in the patients and 17.3% in the control subjects. When the results of the study were evaluated, no statistically significant correlation was found between Her-2/neu codon 655 polymorphism and breast cancer.Key words: Breast cancer, HER-2/neu, PCR-RFLP, Single nucleotide polymorphism