Antitumor Effects of Pronase-Treated Fragments, Glycopeptides, from Ovomucin in Hen Egg White in a Double Grafted Tumor System

Antitumor effects of fragments (220 and 120 kDa, highly glycosylated peptides) separated from Pronase-treated hen egg white ovomucin were analyzed in a double grafted tumor system. BALB/c mice received simultaneous inoculations of Meth-A fibrosarcoma cells on the right flank (1 × 10 6 cells) and left flank (2 × 10 5 cells) on day 0. The two fragments (100 μg/mouse/day) were injected into the right tumor on days 3, 4, and 5, and mice were raised for 21 days. Both fragments cured directly and entirely the right (treated) tumor and inhibited indirectly and slightly the growth of the left (distant) one. Examinations of desialylated 120 kDa fragment indicated that the sialic acid residues in the 120 kDa fragment are not necessarily essential for direct antitumor activity but might be indispensable for regression of distant tumors. The noninhibitory activities in a single tumor system, in which mice received intradermal inoculation of tumor cells only in the left flank, and the increase of immunosuppressive acid protein in serum suggested the slight activation of the immune system.