Construction and identification of anti-HER2 phage display single chain fragment of variable region library in human breast cancer

Abstract

To construct human phage single-chain antibody (scFv) library against breast cancer, and to identify anti-HER2 specific antibodies from the human phage display scFv library to offer a stronger affinity sequence targeting HER2 for fusion protein targeting HER2 and CXCR4. Total RNA was extracted from the adjacent lymphatic tissue harvested from breast cancer patients. The variable regions of the whole antibody were amplified by using RT-PCR and were cloned into the vector pCANTAB-5E through a linker. The products were electroporated into competent E.coli TG1 cells. Recombinant phages specific for breast cancer cells were enriched in SKBR-3 after four rounds. The antigen-positive clones were selected by ELISA and immunohistochemistry. The fragment of VH and VL were about 375 and 330 bp and were linked in vitro to form scFv of 750 bp that was resistant to the breast cancer HER2 single strand. A fusion phage display library that contained total of 2.48×10(8) pfu /ml was established. ELISA and immunohistochemical results confirmed that the antibody has a strong affinity with HER2 antigen in breast cancer tissue. Compared to human IgG antibody, a scFv phage library against human breast cancer was successfully constructed with high capacity. The scFv was highly specific to HER2 antigen and the sequencing results indicated that VL and VH genes were highly homologous with the variable region of human antibody. This strategy may achieve new targeted antibody resistant to the breast cancer for clinical treatment and provide a carrier that uses HER2 as a target of the fusion protein for anti-tumor therapy.