The Establishment of a Cell Line (DL-2) from Experimental Lung Cancer in Dogs and the Studies on the Transplantability of Cultured Cells to Allogenic Dogs

Abstract

A cell line (DL-2) was established from a mongrel dog lung cancer induced experimentally by intrabronchial application of 20-methylcholanthrene. The specimen for tissue culture was obtained from metastatic paratracheal lymph nodes of dog lung cancer, and minced and explanted to Petri dishes. The nutrient medium, maintained at PH 7.2, consisted of RPMI-1640 medium and 20% fetal bovine serum. Cultivation was carried out in a CO₂ incubator. After 90 days of primary culture the cell line was established. The histologic type of implanted lymph nodes was moderately differentiated adenocarcinoma. The author identified the cultured cells as tumor cells by comparing the histology of transplanted tumors in nude mice and chromosomal analysis. The cultured cells are now in the 148th passage, and cells from the 36th to 104th passages were in 11 adult mongrel dogs, 7 young and 6 newborn dogs. Implantation sites included the testes, lung, subcutaneous tissue and the submucosa of the main bronchus (this last by means of a transbroncho-fiberscopic catheter), and the amounts varied from 1 × 10⁷ to 2.2 × 10⁸ cells.
In young dogs, from 24 hours to three months old, the tumor grew in the lung in three out of 7 and lymphatic metastasis occured in two.
In newborn mongrel dogs less than the one day old, a tumor grew in the lung and the testis in one out of 6 impianted and lymphatic metastasis to the thorax and abdomen cocured. Tuomr cells were seen microscopically to the transplanted tissue in three although no tumor developed. A tumor invading the chest wall which developed in a young dog were transplanted to two young and two adult mongrel dogs intrapulmonary after homogenization. A tumor grew in the lung, and metastasis occured in the thoracic lymph nodes and bones in one young dog. The transplanted tumor revealed the same hystologic findings as the original lung cancer induced experimentally. Furthermore, features of bronchiolo-aiveolar carcinoma were seen in the tumor which grew in the lung of a young dog. Thus the DL-2 cell line may be said to be a transplantable cell line.