Proline Rich Polypeptide (PRP-1) Increases the Superoxide-Producing and Ferrihemoglobin Reducing Activities of Cytochrome B₅₅₈ Isoforms from Human Lymphosarcoma Tissue Cells

摘要

The two cytochromes (cyt) b₅₅₈ of acidic nature, one—95–100 kDa and another one, 60–70 kDa were isolated for the first time from the human’s lymphosarcoma tissue cells using gel filtration and ion exchange chromatography. These hemoproteins possess NADPH dependent O₂ −-producing and ferrihemoglobin-reducing activities. The incubation of neuropeptide PRP-1 (5 μg) with cytochrome b₅₅₈, caused elevation of these activities. The gel filtration results indicated possible binding of PRP-1 to these cytochromes b₅₅₈. PRP-1 activated both NADPH dependent O₂ −-producing and ferriHb-reducing activities of the cyt b1 ₅₅₈ and cyt b2 ₅₅₈, obtained from human lymphosarcoma tissue cells. One can assume that PRP-1 associated with cyt b₅₅₈ on the surface of the tumor cells by increasing both NADPH dependent O₂ −-producing and ferriHb-reducing activities of cyt b₅₅₈, increases the oxidation- reduction status. Changing the oxidation–reduction status and oxygen homeostasis of the tumor cells by PRP-1 can serve as one of the possible explanation of antitumorigenic effect of this cytokine.