Studies on the purification of polypeptide from sika antler plate and activities of antitumor

BACKGROUND: We isolated a novel monomeric peptide from antler plate polypeptide (APP) of sika deer and found that it inhibited rat breast cancer cell proliferation and telomerase activity. METHODS: The molecular mass and purity of this polypeptide was determined by ultra performance liquid chromatography (UPLC) and Bruker micOTOF OllQ TOF mass spectrometry, respectively. The full amino-acid sequence of the monomeric peptide was analyzed by sequential Edman degradation using a protein/peptide sequencer. The APP-1 markedly inhibited rat breast cancer cell proliferation as determined with an 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H- tetrazolium bromide (MTT) assay. Then, we used flow cytometry to detect the effects of the monomeric peptide on cell cycle. Relative quantitative fluorescence PCR was used to analyze the expression level telomerase reverse transcriptase (TERT). RESULTS: The molecular mass and purity of this polypeptide was 10646 Da and 91.2 %. Amino acid sequence analyses indicated that the N-terminal amino-acid sequence of this monomeric peptide was: MTKLE DYLEG IVNIF HQYSV. The results showed that monomeric peptide halted most cancer cells stagnating in the G0/G1 phase. The percentage of cells in the G(0)/G(1) is higher than control group after the monomeric peptide treatment. Relative quantitative fluorescence PCR results showed that TERT gene expression level obviously decreased after treatment with the monomeric peptide compared with control group. CONCLUSIONS: Collectively, the results suggest that this novel and monomeric APP has antitumor activities and imply that it is likely an important component of antitumor activities in antler plate polypeptide.