Effects of a Chelating Agent on Brown-Pearce Carcinoma Cells with Special Reference To Their Histological Changes

It is well known that a single tumor may present a great variety of struc• ture at its different parts or metastatic or transplanted foci.The mechanism of occurrence of this diversity in structure of tumor tissues, however, has not been fully investigated.The decreased adhesiveness of tumor cells, their motility, and liberation of a spreading factor, such as hyaluronidase, have hitherto been regarded as responsible for invasive growth of malignant tumors.Of these three factors the first two are of greater importance for invasiveness. 21 Cancerous cells were characterized by reduction in or loss of their adhesiveness to one another. 11 12 1 Many reports, 5 1 6 1 14 J concerning the chemical analysis of tumor tissues, have shown that calcium content in tumor tissues was less than in normal tissues.Coman and his co-workers 1 1-4 1 6 1 12 1 made most exhaustive studies on the invasive growth of cancerous cells.They emphasized that decrease of mutual adhesiveness allowed cancer cells to separate from each other and that such detached cells were enabled to invade the interstitial spaces of the adjacent normal tissues by their ameboid movement, and suggested also that the migratory and invasive character of tumor cells might be due to their reduced calcium concentration.However, confirmative evidence that tumor cells become more invasive by decrease of their mutual adhesiveness has not been completely presented.Recently Popovici et a/. 131reported that disodium versenate chelated calcium ion in preference to other divalent cations in vivo.It is supposed that the chelating agent may decrease adhesiveness of tumor cells with one another and make tumor tissues more invasive in vivo.The aim of this report is to establish the effects of a chelating agent on tumor tissues in vivo. MATERIALS AND METHODSThe tumor used for this investigation was Brown-Pearce carcinoma.Twenty seven male rabbits of mixed breed, 4-5 months of age and weighing about 1 700-2 000 g were used.During this experiment, they were fed with green vegetables alone ad libitum.