Abstract: Objective    To investigate the optimized fixation and storage conditions for the immunohistochemistry detection of phospho-human epidermal growth factor receptor 2 (HER2) on frozen sections. Methods    Xenograft model was established by subcutaneously injecting human breast cancer cell BT474 into the abdomen of BALB/c-nu/nu mice. The mice were sacrificed when the tumor volume up to 300 mm3. The tumor samples were quickly frozen, sectioned, fixed in different reagents and stored for different time period. Phospho-HER2 immunohistochemistry was performed to evaluate the change of protein expression under these conditions. Results    Good cell morphology was kept by the fixation of frozen section in 50% formalin for 5 minutes. The expression of phospho-HER2 protein was stable within 12 weeks after fixation when the tumor tissues were stored in -20 ℃. Conclusion   The immunohistochemistry staining on frozen tissues takes less time and can be a supplement or replacement of traditional staining on formalin-fixed and paraffin-embedded sections. 

Key words: Frozen section, Human epidermal growth factor receptor 2, Immunohistochemistry; BALB/c-nu/nu mice