The role of mortalin on the malignant property of human cancer and molecular mechanism : therapeutic potential of oncolytic adenovirus expressing shRNA against mortalin

Abstract

ABSTRACTMolecular mechanism of the role of Mortalin in human cancers: validation of its therapeutic potential by oncolytic adenovirusJihoon RyuDepartment of Medical ScienceThe Graduate School, Yonsei University(Directed by Professor Man-Wook Hur)Mortalin, a member of Hsp70 family proteins, is an essential chaperone present in various subcellular locations including plasma membrane, ER, cytosol and mitochondria. Functional significance of Mortalin F (full length, a.a., 679) in multiple subcellular locations remains unknown. In this thesis, I prepared stable cells expressing the Mortalin mutant lacking the signal peptide (Mortalin B, a.a., 637) and localizes mostly to the cytosplasm. In cancer cells, ectopic Mortalin B sequesters p53 in cytoplasm revealed strong cytoplasmic sequestration of p53. The cancer cells with Mortalin B overexpressed show high telomerase activity and acquire malignant tumor phenotypes. In xenograft assays, the MCF7 cells overexpressing Mortalin B are highly tumorigenic and form aggressive malignant tumors in nude mice. When the MCF7-Mortalin B cells were injected via tail vein, they showed high degree of lung metastasis.I prepared the oncolytic recombinant adenoviruses expressing shRNA Mortalin (Ad-ΔB7-shMot) to test anti-cancer therapeutic potential both in vitro and in vivo. The Ad-ΔB7-shMot virus shows selective cytotoxicity for cancer cells in vitro. While Mortalin F overexpression enhanced malignant properties of the MCF cancer cells in xenograft assays, Ad-ΔB7-shMot virus showed effective anti-tumor effect. The Ad-ΔB7-shMot virus caused apoptosis and suppressed micro-vessel formation. This study suggests that the Mortalin located outside of mitochondria may be related to malignant property of cancer cells. Because Mortalin F expression is upregulated in various tumors, recombinant adenovirus targeting Mortalin, Ad-ΔB7-shMot, might be useful tool for anti-cancer therapy.