Characterization of vesicles, containing an acylated oligopeptide, released by human colon adenocarcinoma cells. NMR and biochemical studies.

RNA-containing vesicles, recovered from the supernatant of high-density cell samples of human colon carcinoma, produce a high-resolution 1H NMR spectrum of lipids characterized by isotropic tumbling; these vesicles contain large amounts of triglycerides and cholesterol esters. Both findings have strict analogies to what is displayed by the proteolipid complexes isolated from the sera of tumor-bearing patients [(1985) Proc. Natl. Acad. Sci. USA 82, 3455-3459; (1986) FEBS Lett. 203, 164-168]. Lipid analysis and enzymatic tests indicate that these vesicles are selected micromaps of plasma membranes, analogous to those that can be recovered from culture media in which tumor cells are grown [(1985) Dev. Biol. 3, 33-57]. Peculiar lipids, an acylated oligopeptide and a modified phospholipid, are also present in the vesicles.