On the altered nucleocytoplasmic transport "in vitro" of rapidly labelled RNA, in the presence of cytosol or serum from tumor-bearing rats.

Enhanced nucleocytoplasmic RNA transport has been demonstrated by incubating normal rat liver nuclei in presence of cytosols originating from the poorly differentiated, fast-growing hepatoma HW-165, in the linear phase of tumor growth. The effect of hepatoma HW-165 cytosol was reduced or suppressed in presence of small amounts of normal liver cytosol: on the other hand, several polypeptides of molecular weight 20,000 to 40,000 daltons were hardly detectable in hepatoma HW-165 cytosol, both arguments indicating that potentially regulatory proteins should be absent or present in reduced concentration in hepatoma HW-165 cytosol. No modification of RNA release was observed in presence of cytosols originating from the thymus of RNA virus (BL/F)-infected rats, whatever be the time after inoculation. Attempts were made to use the nuclear restriction assay, supplemented with plasma or serum of various origins, as a biochemical marker of neoplasia. In a first series of assays, including 80 cancer patients and 12 healthy controls, the RNA transport activity was stimulated by the serum of patients bearing various tumors (lung cancer, cancer of the respiratory tract, uterine cervix...), except in a few cases of mammary carcinoma, where values equivalent to or lower than the controls were obtained.