Cell surface glycolipids of transformed NIH 3T3 cells transfected with DNAs of human bladder and lung carcinomas.

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RESUMO

Neutral glycolipids and gangliosides of NIH 3T3 cells oncogenically transformed by transfection of DNAs from human lung carcinoma (Lx-1) and human bladder carcinoma (Ej) have been investigated. The chemical quantity and the degree of cell surface exposure of gangliotriaosylceramide (Gg3) were greatly enhanced in NIH 3T3 cells transformed by transfection of DNAs of either Lx-1 or Ej carcinoma cells. An identical but more conspicuous change in cell surface exposure of Gg3 was observed in BALB/c 3T3 cells transformed by murine sarcoma virus Kirsten strain, but the same glycolipid was absent in the original Lx-1 or Ej human carcinomas. The mechanism that defines the chemical quantity and the organization of glycolipids is controlled by multiple factors. These include not only the quantity but also the organization of glycosyl transferases and hydrolases in membranes. This also involves membrane dynamics regulated through a cytoskeletal-membrane conjunction which may determine the degree of glycolipid exposure at the cell surface. The similarity of the chemical and organizational change of a single glycolipid, Gg3, between 3T3 transformants by Kirsten murine sarcoma virus and those by transfection of human cancer DNAs may indicate a common biochemical basis triggered by activation of the oncogene.

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