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Takeshi Fuchigami, Natsumi Ishikawa, Iori Nozaki, Yusuke Miyanari, Sakura Yoshida, Motohiro Yamauchi, Ayumi Soejima, Mamoru Haratake, Morio Nakayama, Discovery of INCENP-derived small peptides for cancer imaging and treatment targeting survivin., Cancer science, 10.1111/cas.14330, 2020.01, Survivin belongs to the inhibitor of apoptosis protein (IAP) family, which is consistently overexpressed in most cancer cells, whereas it is rarely expressed in normal adult tissues. Therefore, the detection and inhibition of survivin are regarded as attractive strategies for cancer-specific treatment. In this study, we designed and synthesized 7-19 residues of INCENP-derived small peptides (INC peptides) as novel survivin targeting agents. The INC peptides demonstrated binding affinity for the human survivin protein (Kd = 91.4-255 nM); INC16-22 , which contains residues 16-22 of INCENP, showed the highest affinity (91.4 nM). Confocal fluorescence imaging demonstrated consistent colocalization of FITC-INC16-22 and survivin in cell lines. Nonaarginine-linked INC16-22 (r9-INC16-22 ) rendered INC16-22 cell penetrable and strongly inhibited cell growth of MIA PaCa-2 cells (52% inhibition at 1.0 µM) and MDA-MB-231 cells (60% inhibition at 10 µM) as determined by MTT assays. On one hand, the exposure of MIA PaCa-2 cells to 40 µM r9-INC16-22 apparently reduced the intracellular protein expression levels of survivin. On the other hand, cleaved caspase-3 was significantly increased in the cells treated with r9-INC16-22 even at 10 µM compared to those in the untreated cells. Flow cytometry revealed that r9-INC16-22 strongly induced apoptosis in MIA PaCa-2 cells. These results indicate that the cytotoxic effects of r9-INC16-22 may be mediated mainly through the disruption of survivin-dependent anti-apoptotic functions and partly because of the direct degradation of the survivin protein. Our findings suggest that INC peptides can act as useful scaffolds for novel cancer imaging and anticancer agents.. |
