Characteristics of hamster cells transformed by the combined action of chemical and virus

Abstract

Pretreatment of hamster cells with chemical carcinogen enhances transformation by a simian adenovirus, SA7. Such transformants were compared to cells transformed by SA7 alone for the presence of virus-specified antigens, and for the ability to clone in soft agar and to form progressively growing sarcomas in hamsters. The SA7 "T" antigen content and the relative cloning efficiencies in agar of cell lines of both groups were similar. Some cell lines obtained by pretreatment with chemical carcinogen, however, produced a higher incidence of tumors, suggesting that the chemical carcinogen was involved in the transformation of cells by virus. A further indication that these cells differed from cells transformed by virus alone was obtained with MCA-transformed fibroblast cell lines that were subsequently also transformed in vitro by SA7 to cuboidal (SA7 type) morphology. These MCA-SA7-transformed cells produced a higher incidence of sarcomas than cells transformed by virus alone, but a lower tumor incidence than the parental MCA line.

Enhancement of adenovirus transformation of cloned rat embryo fibroblast cells by gamma irradiation

“…Comparable results have been obtained in studies employing hamster embryo cells treated with MMS and then infected with SA7 [28,29]. MMS pretreatment did result, however, in an increase in the quantities of SA7 DNA in the total population of hamster embryo cells 2-9 d after MMS treatment and viral infection 1291.…”

“…In the case of the alkylating carcinogen, MMS enhancement of viral transformation of CREF cells was not associated with an alteration in either the biological or biochemical properties of transformants nor was enhancement associated with a change in the quantity of integrated H5hrltransforming genes (E 1 A or E l B) or the integration of viral DNA in similar DNA sites [9,12]. Comparable results have been obtained in studies employing hamster embryo cells treated with MMS and then infected with SA7 [28,29]. MMS pretreatment did result, however, in an increase in the quantities of SA7 DNA in the total population of hamster embryo cells 2-9 d after MMS treatment and viral infection 1291.…”

Potentiating Effect of Methyl Methane Sulfonate on Friend Virus Leukemogenesis in Vivo

“…Chemical carcinogens given prior to subsequent RLV infection of rat embryo cells were ineffective. Conversely, pretreatment by chemical carcinogens has been reported to enhance adenovirus transformation of hamster embryo cells in vitro (5,9). In our in vivo system, a 5-hr pretreatment with MMS in relation to FLV injection enhanced leukemogenesis, but posttreatment did not.…”

“…Ball and McCarter (3) and Igel et al (4) subsequently demonstrated reproducible activation and production of leukemia virus after treatment with chemical carcinogens. These findings have been confirmed in a number of in vivo and in vitro studies suggesting that interaction with exogenous (5)(6)(7)(8)(9)(10)(11)(12) or endogenous (13)(14)(15)(16) viruses may play an important role in the production of some tumors by chemical carcinogens (also see 17 for review). More recently, Pottathil ef al.…”

“…Previous studies have shown that in certain systems potentially oncogenic viruses could be activated by exposure to chemical carcinogens in vivo (3, 4, 6, 13-16, 32, 33), or could interact with chemical carcinogens in vitro (5)(6)(7)(8)(9)(10)(11)(12). The purpose of the present studies was to examine in vivo some of the conditions under which interactions may occur and to determine if given in common the two agents might produce cancer in animals otherwise resistant to induction of the disease.…”