Effect of vasopressin gene expression on the growth of walker 256 carcinosarcoma in rats

The growth pattern of the Walker 256 solid tumor has been studied in rats with different doses of the mutant vasopressin gene. In contrast to the vasopressin gene of normal WAG rats, that of mutant Brattleboro rats has a deletion in the coding region that blocks expression at the translation level. The mutation is inherited as a recessive character and is expressed in homozygous Brattleboro rats as diabetes insipidus with an increased water consumption because of the absence of vasopressin in the blood. (WAG × Brattleboro) F₁ hybrids have the same normal phenotype as WAG rats, including a low water consumption. Walker 256 carcinosarcoma, which is not strain-specific, intensely grows only in WAG and (WAG × Brattleboro) F₁ rats. In these groups, the growth of the tumor leads to the animal death within approximately 30 days after the inoculation of tumor cells. In Brattleboro rats, the carcinosarcoma grows less intensely: the tumor node somewhat increases only within the first two weeks, after which the tumor began to decrease and eventually disappears altogether. Both characters exhibit a 100% concordance at the individual level.