Combined therapy with cyclophosphamide and DNA preparation inhibits the tumor growth in mice.
BACKGROUND
When cyclophosphamide and preparations of fragmented exogenous genomic double stranded DNA were administered in sequence, the regressive effect on the tumor was synergic: this combined treatment had a more pronounced effect than cyclophosphamide alone. Our further studies demonstrated that exogenous DNA stimulated the maturation and specific activities of dendritic cells. This suggests that cyclophosphamide, combined with DNA, leads to an immune response to the tumors that were grafted into the subjects post treatment.


METHODS
Three-month old CBA/Lac mice were used in the experiments. The mice were injected with cyclosphamide (200 mkg per 1 kg body weight) and genomic DNA (of human, mouse or salmon sperm origin). The DNA was administered intraperitoneally or subcutaneously. After 23 to 60 days, one million tumor cells were intramuscularly grafted into the mice. In the final experiment, the mice were pre-immunized by subcutaneous injections of 20 million repeatedly thawed and frozen tumor cells. Changes in tumor growth were determined by multiplying the three perpendicular diameters (measured by caliper). Students' t-tests were used to determine the difference between tumor growth and average survival rate between the mouse groups and the controls.


RESULTS
An analysis of varying treatments with cyclophosphamide and exogenous DNA, followed by tumor grafting, provided evidence that this combined treatment had an immunizing effect. This inhibitory effect in mice was analyzed in an experiment with the classical immunization of a tumor homogenate. The strongest inhibitory action on a transplanted graft was created through the following steps: cyclophosphamide at 200 mg/kg of body weight administered as a pretreatment; 6 mg fragmented exogenous DNA administered over the course of 3 days; tumor homogenate grafted 10 days following the final DNA injection.


CONCLUSIONS
Fragmented exogenous DNA injected with cyclophosphamide inhibits the growth of tumors that are grafted to mice after this combined treatment.
Alyamkina
Ekaterina A
EA
Novosibirsk State University, Novosibirsk, Russia. _just_smile@mail.ru
Dolgova
Evgenia V
EV
Likhacheva
Anastasia S
AS
Rogachev
Vladimir A
VA
Sebeleva
Tamara E
TE
Nikolin
Valeriy P
VP
Popova
Nelly A
NA
Orishchenko
Konstantin E
KE
Strunkin
Dmitriy N
DN
Chernykh
Elena R
ER
Zagrebelniy
Stanislav N
SN
Bogachev
Sergei S
SS
Shurdov
Mikhail A
MA
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