In Vitro Studies of Cytotoxic Effect on Sarcoma-180 Cells of β-Subunit from Egg White Ovomucin

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When sarcoma-180 (SR-180) cells were incubated with α- or β-subunit prepared from insoluble ovomucin in the gel fraction of egg white, the cell proliferation rate was apparently reduced by the addition of β-subunit, while it was largely unaffected by α-subunit. Examinations by scanning and transmission electronmicroscopy indicated a dose- and time-dependent cytotoxic effect of β-subunit on SR-180 cells, whereas β-subunit did not injure mouse peritoneum macrophage used as normal cells. Ultrastructurally, SR-180 cells treated with β-subunit showed changes such as swelling and bleb formation of microvilli on cell membrane, irregular clumping of chromatin, irregular nuclear shape, and marked swelling of organelles in cytoplasm associated with cell degeneration in necrotic change. Furthermore, apoptotic analysis of the cultured SR-180 cells also demonstrated that β-subunit did not induce the apoptotic DNA fragmentation.