Japanese Journal of Oral and Maxillofacial Surgery
Online ISSN : 2186-1579
Print ISSN : 0021-5163
ISSN-L : 0021-5163
Lipid metabolisms of normal epithelial cells and cancer cells derived from oral region in serum-free culture
Tsunei SHINKITetsuji OKAMOTOKazuaki TAKADA
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1992 Volume 38 Issue 2 Pages 222-228

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Abstract

We have previously reported that sensitivity to various antitumor drugs on squamous carcinoma cells is different from that on adenocarcinoma cells.Furthermore, the difference is well correlated with the ability of the cells to incorporate drugs by passive transport. These results suggest the possibility that the accumulation of the drug was closely associated with lipid composition and/or conformation which is thought to be an important factor to determine hydrophobicity of the cell membrane.
Generally, serum-contained medium was used to study lipid metabolism in cultured cells. Since lipid metabolism is dependent upon the presence of external lipoproteins, we have studied lipid metabolism of normal epithelial and cancer cells in serum-free culture to evaluate intrinsic lipid metabolism in the cells.
[2-14C] acetate was incorporated almost exclusively into phospholipids in oral epithelial cells cultured in a low calcium medium. However when the concentration of calcium was changed from 0.03 mM to 1.12mM to induce terminal differentiation of the cell, a definite amount of radioactive acetate was incorporated into free cholesterol and incorporation into phospholipids was decreased. The extent of the incorporation into free cholesterol was increased at least until 48 hrs after inducing differentiation and the ratio of free cholesterol over phospholipids were constantly increased in this period, indicating that accumulation of free cholesterol is concomitant with the differentiation of the cell.Furthermore, it may be suggested that the ratio of free cholesterol over phospholipid could be an indicator for terminal differentiation of epithelial cells.Squamous cell carcinoma cells which showed a decreased capacity to differentiate exhibited increased incorporation into phospholipids and decreased incorporation into neutral lipids. On the other hand, adenocarcinoma cells showed marked differences in lipid metabolism compared to squamous carcinoma cells, i.e., increased incorporation into neutral lipids and decreased incorporation into phospholipids.
From the results obtained, it is clear that a close relationship exists between lipid metabolism and the ability of cells to differentiate. Furthermore, it may be suggested that hydrophobicity of the cell membrane in squamous carcinoma cells might be higher than that in adenocarcinoma cells.

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© Japanese Society of Oral and Maxillofacial Surgeons
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