Regression of Walker 256 carcinosarcoma in vasopressin-deficient Brattleboro rats is accompanied by a changed laminin pattern.

Walker 256 carcinosarcoma is a transplantable model of rat carcinoma that originally appeared spontaneously in mammary glands. The growth rate of Walker 256 carcinosarcoma in vasopressin-deficient Brattleboro rats is lower than in WAG rats and their congenic hybrids with normal vasopressin levels. Study of tumor proteins detected essential alterations. Tumor regression starting at the 14th day in Brattleboro rats was accompanied by changes in the laminin pattern. At the 21st day, the concentration of α-chains became twice as low, while β-chains of laminin showed a sixfold increase compared to the initial equimolar correlation of bands. Congenic hybrids having one active copy of the vasopressin gene to provide a physiological level of hormone against the genetic background of Brattleboro rats show the same laminin alterations as WAG rats. They demonstrated a similar moderate increase of γ-chains and threefold growth of α- and β-chains of laminin in tumor tissue. It is supposed that vasopressin may be involved in the regulation of relevant local stimuli to trigger renovation of the laminin composition in a course of growing Walker 256 carcinosarcoma.