| Summary: | 碩士 === 長庚大學 === 基礎醫學研究所 === 89 === Nucleophosmin/B23 is a maior nucleolar phosphoprotein, which is more abundant in tumor and proliferating cells than in normal cells. It may be one of the elements in the regulation of nucleolar function. Recent studies have shown that protein B23 forms a specific complex with the human immunodeficiency virus type Ⅰ(HIV-1) Rev protein. Some synthetic peptides, including Rev-NLS peptide (ARRNRRRWREYC), Rev 40~46 peptide (NRRRRWEYC) and T-NLS (PKKKRKVEDPYC), were reported to contain the NLS sequence of HIV-1 Rev protein and SV40 large T-antigen. These peptides have different affinity to protein B23, but their biological effects remain unclear. Therefore, it is the first time to examine the biological effect of these B-23 binding peptides on human osteosarcoma MG-63 cells.
Actinomycin D (Act-D), an anti-tumor antibiotic and RNA synthesis inhibitor, has been used to treat a variety of pediatric malignant tumors (Frei, 1974; Green et al., 1988). Recent studies have shown that Act-D could also induce apoptosis. In this study, attempts were made to determine whether the biological effects of Rev-NLS peptide could be enhanced by Act-D co-treatment. Our results suggest that NLS-containing peptides with high B23 binding affinity (Rev-NLS and Rev 40~46) have a lethal effect on MG-63 cells during serum deprivation. In the contrary, NLS-containing peptides with low or without B23 binding affinity (T-NLS and np-NLS) have little effect on MG-63 cells during serum deprivation, whereas serum interferes with the cytotoxicity of Rev-NLS peptide. MG-63 cells treated with B23-binding peptides exhibit a complex picture of early apoptosis and late necrosis in Annexin V and PI staining with flow cytometric analysis. Rev-NLS peptide has a synergistic effect on cell death with Act-D co-treatment. Collectively, this study demonstrated that the cytotoxicity effect of B23-binding peptides is related to B23.
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