title: [Effect of anti-tumor agents cisplatin and cycloplatam on membrane protein kinase C activity in murine T-lymphocytes].
abstract: The effect of cisplatin and the new drug cycloplatam (amine (cyclopentylamine)-S-(-)-malatoplatinum (II)) on protein kinase C (PKC) activity and Ca(2+)-dependent binding of PKC to T lymphocytes membranes was studied in vivo and in vitro. At first, the effect of the drugs on PKC activity of intact and activated lymphocytes was studied in vivo. In 48 hours after intraperitoneal injection of mice with therapeutic doses of the drugs, PKC activity of intact lymphocytes was differentially affected. Cisplatin did not practically alter the enzyme activity, whereas cycloplatam inhibited the PKC activity by 37% versus control. In lymphocytes activated by mouse P-388 leukemia cells in vivo, the drugs caused almost complete suppression of PKC activity and Ca(2+)-dependent binding of the enzyme to the membranes. The drugs were effective in intact cells. After incubation of intact lymphocytes in vitro for 24 hours with cisplatin or cycloplatam (10(-5)M), PKC activity was increased 1.62- and 1.35-fold, respectively, versus control. Ca(2+)-dependent binding of the enzyme to the membranes was also increased 1.61- and 1.36-fold by cisplatin and cycloplatam, respectively. On the contrary, at 10(-4) M concentration under similar conditions, the drugs did not affect the PKC activity of the lymphocytes. Furthermore, cycloplatam, unlike cisplatin, reduced the PKC binding to cellular membranes by 31%. The mechanisms of the drugs effects on PKC activity are suggested. The data indicate that increase or decrease of PKC activity induced by the drugs cause stimulation or depression of functional activity of T lymphocytes, respectively. Thus, the membrane-bound PKC can play the key role in initiation and development of immunomodulatory effects of cisplatin and cycloplatam.
authors.forename: S V
authors.initials: SV
authors.lastname: Khabarov
authors.forename: G K
authors.initials: GK
authors.lastname: Gerasimova
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology; D002945:Cisplatin / Q000494:pharmacology*; D051379:Mice; D008811:Mice, Inbred DBA; D009944:Organoplatinum Compounds / Q000494:pharmacology*; D011493:Protein Kinase C / Q000187:drug effects* / Q000378:metabolism; D013601:T-Lymphocytes / Q000187:drug effects* / Q000201:enzymology
chemical_list: D000970:Antineoplastic Agents; D009944:Organoplatinum Compounds; C055928:cycloplatam; D011493:Protein Kinase C; D002945:Cisplatin