Search

The effect of a single injection of doxorubicin, 8-day administration of two 5-hydroxypyrimidine derivatives, SNK-411 (2-Isobutyl-4,6-dimethyl-5-hydroxypyrimidine) and SNK-578 (hydrochloride of 2-isobutyl-4,6-dimethyl-5-hydroxypyrimidine), on metastases, lifespan and serum cytokines has been investigated in С57ВL/6 mice after removal of a primary tumor node of Lewis lung carcinoma (LLC). LLC cells (1×106) were injected in the footpad of right hind feet of mice in control and experimental groups; after 14 days of tumor development the hind feet with the tumor were amputated at the ankle level. One hour before the amputation mice received a single injection of doxorubicin (4 mg/kg) and 8-day therapy with the 5-hydroxypyrimidine derivatives started. SNK-578 monotherapy was performed at a dose of 10 mg/kg administered intraperitoneally (i.p.). SNK-411 was administered per os at a dose of 25 mg/kg. In the case of combined therapy mice also received a single injection of doxorubicin (4 mg/kg; i.p.). The metastasis inhibition index in mice-treated with SNK-411 and SNK-578 were 53.3% as compared with control mice (with removed tumor). The mice-treated with SNK-411, doxorubicin, and the combination SNK-578 + doxorubicin had lifespan increased by 60.2%, 53.9%, and 42.9%, respectively. A single injection of doxorubicin, the course administration of the 5-hydroxypyrimidine derivative alone and in combination with single injection of doxorubicin completely decreased serum levels of the prooncogenic Th2-cytokines IL-4, and IL-6 and significantly decreased the level of the Th2-cytokine IL-5. Administration of doxorubicin, SNK-411 and SNK-578 did not influence serum concentration of Th1-cytokine interferon gamma (IFN-γ). These data confirm our previous findings that administration of the compounds studied decreased concentrations of prooncogenic IL-4 and IL-6 in tumor-bearing mice with LLC and had no effect on concentrations of the Th1-cytokine IFN-γ.

The effects of intraperitoneal administration of SNK-411 (2-isobutyl-4,6-dimethyl-5-hydroxypyrimidine) in a dose of 25 mg/kg (the total dose of 350 mg/kg) and SNK-578 (hydrochloride of 2-isobutyl-4,6-dimethyl-5- hydroxypyrimidine) in a dose of 10 mg/kg (the total dose of 140 mg/kg) on tumor growth and concentration of cytokines in the blood serum were studied in female CBA mice. Substances were administrated from the 2nd to 15th days of tumor development. Tumor growth inhibition (TGI) and serum cytokine level were studied on the 7th day after the end of compounds administration (21st day of tumor growth). In intact control group (n=10) median tumor mass was 1255 mg. TGI in the group of animals treated with SNK-411 was 47%; in the group of mice treated with SNK-578 TGI was 87%, tumor mass demonstrated 7.4-fold reduction. Serum concentrations of cytokines (IL-6, IL-10, IL-17A and IFN-γ) in tumor-bearing group of mice were higher versus the intact control group by 229%, 40%, 60% and 81%, respectively. Highly active SNK-578 decreased concentrations of prooncogenic IL-10, IL-17A and proinflammatory IL-6, by 61%, 70% and 29% as compared to tumor-bearing control group. SNK-411 decreased concentrations of prooncogenic IL-10 and IL-17A by 48% and 60%, respectively, and did not affect concentration of IL-6. Taking into consideration that IL-6 participates in autoimmune reactions, we can assume that the immune control is one of the crucial mechanisms of antitumor effect of SNK-578. All results are statistically significant.