The Chromosomes of Tumors Induced in Mice by Human Adenovirus, Type 12.

Abstract

Human adenovirus, type 12, when injected into newborn hamsters( l ) , rats(2), mice(3), or mastomys (4) induces undifferentiated tumors at site of injection. This communication concerns a chromosome study of tumors so induced in mice.Materials and methods. Cells were studied from primary tumors in four C3HfGs mice and from 71 tumors representing the first (37 animals) and second (34 animals) passages of these tumors. The 4 primary tumors were obtained from animals ( 2 females, 2 males) injected intraperitoneally when newborn with 0.05 ml of human adenovirus type 1 2 (A12S9). Most of the animals used for tumor passage were males and were injected with tumor mince or cell suspensions when adult. The resulting tumors were harvested after 2-6 weeks of growth. Two of the animals with primary tumors were treated with colchicine and 2 were untreated. All of the animals carrying tumor passages were colchicine treated (1 pg per gram body weight). The animals were injected with colchicine 1-3 hours before they were sacrificed by rupture of the cervical spinal cord. Tissue culture studies were done on all animals, and sections for pathology on most. Routine air dry techniques and temporary squash methods were used in making the chromosome preparations from finely minced tumor tissue. Most of the studies for structural aberrations were done from temporary orcein squash preparations, since these had a higher proportion of * Supported by grants from the Anna Fuller Fund t Present address: Schweizerisches Forschungs Inst., and Nat. Cancer Inst., U.S.P.H.S. Davos Platz, Switzerland.cells with chromosomes lying separately in one plane. The minced tissue was suspended in saline, which was subsequently diluted 1:4 with distilled water, allowed to stand 7-20 minutes, and then centrifuged a t 2000 rpm for 5 minutes. The supernatant was decanted, and 1 ml of fixative (60% acetic acid) was layered over the button of cells. After one hour or longer the acid was decanted, and 1 ml of acid orcein dye (2% orcein in 60% acetic acid) was added. The cells, resuspended in the solution, were used for making squash preparations. Terminology for chromosome variation is employed in accordance with definitions used in classical genetics adapted to present day cytogenetics ( 5).Results and discussion. Results of the investigation are summarized in Tables I and 11. Material from the original tumors, passage tumors, and tissue cultures showed essentially the same findings: aneuploidy, polyploidy, mixoploidy, low rates of endoploidy (5/2r>ol cells), and relatively few structurd aberrations ( 17/804). Very few chromosomes other than normal telocentrics were present. Most of the cells (2001) analyzed for chromosome number (Table I) were in the d i p loid range of 30 to 50, 56% having the normal number of 40 telocentric chromosomes per cell. Fig. 1, showing the distribution of the chromosome number in the original tumors and the first and second passages of the tumors, demonstrates the likely presence of mixoploidy. All show a peak at 42 (2 N = S = 2x + ...