Human lymphocytes treated with r-7, t-8-dihydroxy- t-9,10-epoxy-7,8,9,10-tetrahydrobenzo[ a]pyrene require low-density lipoproteins for DNA excision repair

Abstract

Human lymphocytes which were non-mitogen-stimulated, and which were depleted of lipoproteins, were found to be deficient in DNA excision repair typically initiated in these cells in response to treatment with a direct-acting polynuclear aromatic hydrocarbon carcinogen. Lymphocytes either depleted of lipoproteins or supplemented with human low-density lipoproteins formed DNA—carcinogen adducts which were not chromatographically distinguishable. The state of lipoprotein depletion did not alter lymphocyte uptake of thymidine from the medium. Lymphocytes which are depleted of lipoproteins, treated with carcinogen, and subsequently supplemented with low-density lipoproteins, regained the ability to engage in DNA excision repair. The data suggest that either low-density lipoprotein(s), or a component(s) of low-density lipoprotein(s), is required by human lymphocytes in order to initiate excision repair of carcinogen-damaged DNA.