Incorporation of conjugated linoleic acid in mouse keratinocytes

Conjugated linoleic acid (CLA) has been shown to inhibit mouse skin tumor promotion To evaluate whether CLA was able to be incorporated into keratinocytes, the uptake of I4C-conjugated linoleic acid (CLA) was compared to the incorporation of l4C-linoleic acid (LA) and 14Carachidonic acid (AA) over time The mouse keratinocyte cell line, HEL30, was grown in serum free media, 0.1% albumin and O.luCi/ml I4Cfatty acid (LA, CLA or AA) for various time points (0.5-24 hr) Incorporation of the fatty acids was maximal by 12 hr and approximately 85-90% exogenous radiolabeled fatty acid was incorporated into cells by 24 hr Incorporation of 4C-CLA into keratinocytes was slightly lower compared with uptake of I4C-LA or I4C-AA The incorporation I4C-I.A and I4C-CLA into phospholipid fractions was similar The majority (-57%) of I4C-LA or C-CLA was incorporated into phosphatidylcholine (PC) with phosphatidylethanolanie (PE) and phosphatidylserine/ phosphatidylinositol (PS/PI) containing 15%-27%. In contrast, 14C-AA incorporation was evenly distributed into PC (29%), PE (29%) and PS/PI (39%) To determine competition of CLA and LA for incorporation, cells were cultured in serum free media with I4C-LA 0 IfiCi/ml and unlabeled CLA (0, 1,4. 16 ng/ml) for 12 hr. At various doses, CLA inhibited I4C-LA incorporation into phospholipids. In summary, CLA and LA were incorporated into keratinocyte phospholipids in a similar and competetive manner (Supported by ACS IRG 1735).