Tumor Lipids: The Comparative Lipid Content of the Periphery and Center

Abstract

Introduction Bullock and Cramer (1914) analyzed transplantable tumors of mice and rats in an effort to obtain information concerning the presence of lipid substances in rapidly growing cells. In addition to finding that phospholipids were more abundant in rapidly growing tumors than in slowly growing tumors, they found that healthy, non-necrotic portions of a mouse carcinoma contained a lower amount of phospholipid calculated as percentage of dry residue than did necrotic portions of the same tumor. Cholesterol was found only in traces and cholesterol esters were absent from both kinds of tissue. Analyses of peripheral and central portions of Flexner-Jobling rat carcinoma by Uramoto (1932) showed higher free and bound cholesterol and water contents in the center of the tumor, while the values for lipid phosphorus were very nearly the same for both tissues. Bierich and Lang (1933) analyzed intact peripheral and necrotic central portions of a Jensen sarcoma, finding a great increase of cholesterol ester and a great decrease of phospholipid in the necrotic central portion. Brikker and Lasaris (1932) reported opposite results on the Ehrlich mouse carcinoma, since they found a higher proportion of cholesterol to lecithin in the periphery than in the center. The analyses of peripheral and central portions of tumor tissue reported in this paper were undertaken to determine, first, the portions of tumor to be used for future lipid analyses; second, the changes in the lipid partition of a tissue due to necrosis. The blood supply to the center of the transplantable rat tumor used is so poor that, for the most part, the lipids formed from those of the outer or growing tissue should remain within the tumor. Experimental Tumor: The tumor used was rat carcinosarcoma 256 obtained from the Institute of Cancer Research, Columbia University. Young male rats weighing from 70 to 100 gm. were inoculated subcutaneously in the groin by the trocar method. The tumors were removed when they had attained a size such that sufficient tissue could be obtained from the center for analysis. Their age varied from twenty-seven to fifty-two days depending on their growth rate.