Background: Understanding of cellular and molecular mechanisms involved in cell/tumor growth and progression has led to molecular-targeted therapy. HER1 and HER2 are two main oncogenic components of HER-receptor family considered as targets for cancer research and therapy. Reliable results of HER- related research and targeted therapies dependent upon cell line with known HER expression status. But there are no published studies focusing on determination of HER1 and HER2 receptors expression in CHO and HEK-293 cell lines. Materials and Methods: Absolute expressions of HER1 and HER2 in CHO, HEK-293, MDA-MB-468 and SKBR3 cells were evaluated using quantitative real-time PCR. Absolute expression quantification was carried out by serial dilution plasmids harboring HER1 and HER2 to extrapolate standard curve. Results: Real-time PCR amplification was successfully optimized by HER1 and HER2 plasmids with high efficiency and their copy numbers were calculated. The results showed that HER1 was not expressed in CHO and HEK-293 cells but these cells express HER2 up to 9.4 × 102 and 1.1 × 105 copy/µg, respectively. MDA-MB-468 and SKBR3 cells express HER1 up to 8.4 × 105 and 9.7 × 104, respectively. In addition, the expression of HER2 is higher on the surface of SKBR3 cell (6.5 × 106 copy/µg). Conclusion: Our study provides a proven insight to HER1 and HER2 expression status in CHO, HEK-293, MDA-MB-468 and SKBR3 cells. Heterologous expression of HER1 and HER2 in cell lines is the first step in structural and functional studies. Since HER1 is not expressed in CHO and HEK-293 endogenously, these cells are ideal for HER receptor related studies.
