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The transformation of nonhuman primate marmoset cells by Rous sarcoma virus of Schmidt-Ruppin strain (RSV-SR) generates transformants which lack tumorigenicity in allo- and xenogeneic hosts. Marmoset cells acquire this property when they are transformed by RSV rescued from non-tumorigenic allogeneic cells. One of the rescued RSV, when used to infect marmoset kidney cells in vitro, yielded transformants which became tumorigenic in adult allogeneic hosts. Cytogenetic and molecular analyses of transformants revealed progressive genetic changes from cell diploidy to aneuploidy and from the presence to the loss of v- src during propagation in vitro. The loss of v- src in transformed cells coincided with the evolution of aneuploid cell clone with specific marker chromosome (M1). Although both early passage diploid and late passage aneuploid transformants were tumorigenic, the induced tumors originated from different type of cells. Tumors induced by diploid- and v- src —positive transformants were derived predominantly from the host cells, while tumors induced by late-passage transformants and with deleted v- src originated from an aneuploid cell clone that contained a rearranged M1 marker chromosome. These results suggest that besides the v- src oncogene, proviral integration can facilitate chromosomal rearrangements that contribute to tumorigenic transformation of nonhuman primate cells in vitro.

Type C virus produced by dog thymus cells (A7573) that were infected with virus (HL-23V), isolated from cultured leukocytes of an acute myelogenous leukemia patient, transformed marmoset and horse cells in vitro and induced virus-producing fibromas in marmosets. The tumors and transformed foci were indistinguishable morphologically from those induced by simian sarcoma virus, type 1 (SSV-1/SSAV-1). HL-23V was indistinguishable from SSV-1/SSAV-1 by immunofluorescence and neutralization tests, and the nontransforming virus associated with HL-23V completely inhibited SSV-1 focus induction in interference tests. Cell cultures established from a marmoset fibroma produced transforming and nontransforming virus biologically and antigenically indistinguishable from HL-23V and SSV-1/SSAV-1.

Skin fibroblasts derived from three patients with familial polyposis coli (FPC) were treated in vitro with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) alone or in combination with the tumor promoter, 12-O-tetradecanoylphorbol-13-acetate (TPA). None of the cultures treated four times with MNNG alone (1 microgram/ml) or in combination with TPA (eight applications, 0.1 microgram/ml each) showed either morphological transformation or anchorage-independent growth for 18 months after treatments. FPC cells treated with MNNG alone showed cell growth inhibition, breakage and loss of chromosomes, as well as the deletion of 5.7 kilobase (kb) EcoRI fragment in the c-K-ras locus as detected by Southern blot analysis with v-K-ras specific probe (clone KBE-2). The control cells contained two EcoRI fragments of 5.7 and 4.2 kb. On the other hand, cells treated with MNNG first and then followed by treatment with TPA not only showed an increase in the rate of cell growth but also exhibited two novel EcoRI fragments of 9.4 and 12 kb. Treatment with TPA alone appeared to stimulate cell division long after application and to induce chromosomal aberrations but had no effect on c-K-ras sequences. The most likely explanation for the appearance of chromosome pulverization and hyperploidy in FPC cells treated with TPA is the induction of premature chromosome condensation of the S phase cells due to fusion with the mitotic chromosomes.

Cytogenetic studies of African cane rat (Thryonomys swinderianus) established a diploid chromosome number for this species 2n=44. Among 21 pairs of autosomes, one pair of large submetacentric chromosomes possess secondary constriction and satellites on the shorter arms. The X chromosomes are the largest metacentrics while the Y chromosomes is the smallest of the complement. The karyotypic similarities between African cane rat and other hystricomorph rodents are briefly discussed.

We have analyzed the DNA of marmoset tumors induced and marmoset cells transformed by Rous sarcoma virus (RSV) and derivative viruses of various types. Southern blot hybridization was used to determine the presence of v-src gene sequences. We failed to detect v-src DNA in high-passage cells derived from marmoset tumors induced in vivo or from marmoset cell lines transformed in vitro. The inability to detect src sequences was not related to selection of revertants in culture, since all cell lines retained transformed morphology and cells transformed in vitro retained the ability to induce sarcomas after transplantation into adult allogeneic marmosets. By contrast, we detected integrated proviruses in cells analyzed 32 to 60 days after in vitro transformation. The proviral sequences appeared to be identical to the transforming virus but were apparently unstable and continued to transpose.

The tumors induced in white-lipped marmosets (Saguinus fuscicollis, S. nigricollis) by Rous sarcoma virus (RSV) of chicken origin (RSV-SR) were not transplantable to allogeneic hosts. In contrast, RSV rescued from these tumors (RSV-M) induced sarcomas that were transplantable to young but not to adult marmosets. The tumors induced by RSV-M and the transplants rapidly enlarged, metastasized to various organs, and killed the recipients 29-59 days post inoculation. Cell lines were readily established from all transplantable sarcomas. No virus expression was detected in transplantable tumor cell lines by electron microscopy or by biochemical and biological assays. However, RSV of the same subgroup as RSV-SR was rescued from both short-term and long-term tumor cell cultures by cocultivation with chicken embryo fibroblasts (CEF). The rescued viruses transformed marmoset cells 100-fold more efficiently than CEF cells, although CEF cells remained permissive for virus replication. Cytogenetic studies revealed extensive chromosome abnormalities in tumor transplants but not in RSV-M-induced sarcomas. All cell lines were hyperploid and contained structurally abnormal, large metacentric and telocentric chromosomes. Immunologic studies failed to detect group-specific (gs) antigen of the avian sarcoma-leukemia complex in either RSV-M-induced, transformed cells or tumor transplants. By complement-dependent cytotoxicity assays, with the use of marmoset anti-gs serum, RSV-associated antigen could be detected on the surfaces of tumor cells. No differences in the expression of this antigen existed between transplantable and nontransplantable marmoset sarcomas. All transplantable cell lines contained abnormal amounts of lipids and glycogen in comparison to RSV-SR-induced tumors and normal marmoset cell lines. The glycogen was associated with unique cytoplasmic membrane complexes and was surrounded by either single- or double-membraned vesicles.

Rat embryo cells subjected in vitro to transient incubation at an elevated temperature (39 degrees C) became transformed and induced fibrosarcomas in both homologous and heterologous hosts. Malignant transformation correlated with the occurrence of karyotypic changes which appeared long after incubation at 39 degrees C and subsequent return to 37 degrees C. Control cultures incubated at only 37 degrees C did not show similar chromosomal changes or induce tumors and remained predominantly diploid during the same observation period. In contrast to rat embryo cells, marmoset monkey cell cultures incubated at 39 degrees C did not develop characteristics of transformed cells.

Epstein-Barr virus obtained by superinfection of Raji cells with Epstein-Barr virus recovered from P3HR1 cells (HRI virus) transformed human lymphocytes, but it did not superinfect Raji cells. A human lymphoblastoid cell line, HLB, established by such transformation contained 22 Epstein-Barr virus genomes per cell and Epstein-Barr virus-associated nuclear antigen, and a few cells contained early or viral capsid antigen complexes. Chromosomal analysis revealed that HLB-cells were diploid with normal female karyotypes. Replication of Epstein-Barr virus DNA and inhibition of host cell DNA synthesis were observed in HLB cells after superinfection with HR1 virus.

Genetic analyses have defined a single gene ( src ) as that portion of the avian sarcoma virus (ASV) genome which encodes the protein directly responsible for ASV-induced neoplastic transformation. We have recently identified the polypeptide product of the src gene of the Schmidt-Ruppin (SR) strain of ASV, a 60,000-dalton phosphoprotein designated pp60 src , and have further determined that pp60 src acts as a protein kinase. Essential to the identification and characterization of the pp60 src protein of SR-ASV was the use of serum (TBR serum) from rabbits bearing SR-ASV-induced tumors. TBR serum was, however, strain specific, recognizing pp60 src from SR-ASV-transformed cells only. We report here that sera from marmosets bearing tumors induced by the Bryan or SR strains of ASV (TBM sera) contain antibody which precipitates the transforming gene product from cells transformed by the SR, Bryan, Prague, or Bratislava strains of ASV. In contrast, rabbits bearing tumors induced by either the Bratislava or Bryan strains of ASV, or hamsters with SR-ASV-induced tumors did not produce antibody to pp60 src from any strain of ASV. The 60,000-dalton polypeptides immunoprecipitated with TBM serum from cells transformed by each of the above virus strains are phosphoproteins. One-dimensional peptide mapping by limited proteolysis revealed that the pp60 src proteins are structurally very similar, but not identical. Furthermore, all of the viral pp60 src proteins have an associated phosphotransferase activity. In addition to detecting the viral src proteins, TBM serum was able to immunoprecipitate an antigenically related protein from normal uninfected avian cells.

Cytogenetic analysis of the native African pig revealed the presence of auto-somal mosaicism (38/37) in bone marrow tissue. The population of cells with 37 chromosomes show unbalanced karyotype, lacking on large autosomal acrocentric chromosome. The significance of this finding in relation to the karyotype of the European domestic pig (Sus scrofa) and intraspecies hybrids is discussed.

Human osteosarcoma and mammary carcinoma cells were cultured separately in a medium supplemented with fetal calf serum, until they were confluent. The medium was then replaced by serum-free medium supplemented with heparin. Both cell cultures secreted collagenase, and this activity was inhibited by a cartilage-derived protein of low molecular weight. Since cartilage is rarely invaded by neoplasms, the presence of this inhibitor may play an important role in the regulation of tumor invasion.