COMPOSITION AND TURNOVER OF PHOSPHOLIPIDS AND NEUTRAL LIPIDS IN HUMAN BREAST-CANCER AND REFERENCE TISSUES

The phospholipid (PL) content was 4-fold higher while the triacylglycerol (TG) content tended to be 65% lower in human breast cancer tissues as compared with non-cancerous reference parts from excised breast tissues. The variation in TG content among breast tissues was very large while that of PL was relatively small. The fatty acid compositions of PL were significantly different between tbe cancer and reference tissues; the proportions of octadecenoate (18:1), docosahexaenoate (22:6n-3), the total n-3 fatty acids and the n-3/n-6 ratio, but not the proportion of arachidonate (20:4n-6), were significantly higher in the major PL of cancer tissues as compared with those of the reference tissues. No significant differences were observed in the proportion of the major fatty acids of TG in these tissues. The turnover of lipids was faster in the cancer tissues than in the reference tissues. The turnover of TG was faster than that of PL in the cancer tissues, whereas the opposite was true in the reference tissues, indicating significant differences in lipid metabolism between these tissues. A striking difference in the n-3 and n-6 fatty acids of the reference tissues noted for Japanese and Finnish women is discussed in relation to the roles of eicosanoids and eicosanoid precursors in mammary carcinogenesis.