The Establishment of a Transplautable Spindle Cell Tumor, Originating from a Mammary Cancer Induced in Rats with 7, 12-DMBA and the Effects of Hormones and Drugs upon its Growth.

Abstract

Trials were made on the subcutaneous heterotransplantation of primary mammary cancers induced by oral administration of 7,12-dimethylbenz(α)anthracene in home-raised female rats of the Sprague-Dawley strain (SD/K) to the back of the young, progesterone-treated or cortisonized SD/T (a subline of the Sprague-Dawley strain, delivered from a dealer) female rats. The transplantations were successful only in the cortisonized rats. Further serial subcutaneous transplantations to the 2nd and 3rd generations of the cortisonized SD/T rats were carried out, and finally the 4th transplantation to the homegrown SD/K rats. The takes and growth rates became higher in the SD/K rats when cortisonization was no longer required for the takes. Since then 45 serial subcutaneous transplantations have been done during the past 3 years, and they are being continued.
The histological appearance of the primary tumor was adenocarcinoma (Photo 2. ), which could still be seen in the 2nd and 3rd transplantations even though the spindle cell tumor pattern gradually increased (Photo 3. and 4. ). Adenocarcinomatous pictures could not be detected from the 4th transplantation (Photo 5. and 6. ). The histological appearance of the spindle cell tumor did not alter in the subsequent serial transplantations of the tumors to the SD/K rats (Photo 8. ).
The transplantation rates in each generation were almost 100%, and the growth rate of the subcutaneous tumors and the survival time of the hosts were almost the same in each generation. The heterotransplantations of the tumor, however, were impossible in the sublines of the Sprague-Dawley strain (SD/T, SD/Y, and SD/S) and the Wistar and Donryu strains, all of which had been obtained through dealers.
The trypsinized tumor cells were inoculated into the peritoneal cavity of the SD/K rats. Hemorrhagic ascites including tumor cells came out, which were applied to the serial intraperitoneal transplantations. Finally, an “ascitic tumor” was established. Subcutaneous inoculation of the ascitic tumor in turn yielded the spinde cell tumor. When a small piece of the subcutaneous tumor was intubated into the peritoneal cavity, many solid spindle cell tumor were produced in the mesenterial and retroperitoneal regions.
The effects of the steroid hormones were observed on the growth rate of the subcutaneous transplanted tumor in the 12th transplantation generation. Cortisone inhibited their growth, while sex hormones did not influence it. The growth curve of the tumor in the SD/K rats, interpreted by the tumor size per days after transplantation, was more accelerated in the males than in the females. Hormonedependency has been reported in the great majority of DMBA-induced mammary cancers in rats, but, according to the present investigations, the transplantable tumor seems to be hormone-indipendent.