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Isozyme phenotypes of polyoma virus tumors in mice
Abstract:
Isozyme profiles for 32 enzyme systems were studied in tumors induced by two strains of polyoma virus (2PTA and LID1), in two conventional mouse strains (C3H/BiDa and NIH), and in athymic (nude) mice of two genetic backgrounds (C3H/Hes nu/nu and NIH nu/nu). Tumors studied were: primary and transplant passages of salivary gland tumors (127); primary thymic epithelial tumors (12); primary subcutaneous sarcomas (6); primary hair follicle tumors (5); primary and transplant passages of mammary tumors (18); primary ameloblastomas (3); and primary renal medullary sarcomas (3). Regardless of mouse strain or virus strain, the isozyme arrays were highly constant and unique for each tumor histotype with the exception of salivary and mammary tumors, which shared a single profile differing from that of each of the other histotype-associated profiles. Other tumor types could be distinguished from each other and from the salivary-mammary tumor pair by as few as five isozymes: glycerol-3-phosphate dehydrogenase; glyceraldehydephosphate dehydrogenase; lactate dehydrogenase; sorbitol dehydrogenase; and alkaline phosphatase. Twelve nonpolyoma mammary tumors and their passages from mouse mammary tumor virus-expressed C3H/Hes nu/+ mice were analyzed for the same enzymes; variations in activity and isozyme profiles were found for ten enzyme systems. Three spontaneous salivary myoepitheliomas in BALB/c mice were also analyzed; two different lactate dehydrogenase profiles were observed, and all three tumors lacked the placental alkaline phosphatase present in polyoma virus-induced salivary tumors. Uniformity of isozyme phenotype may be characteristic of DNA virus transformation of cells in a particular differentiative state. This uniformity does not appear to occur in mouse mammary tumor virus-associated tumors, spontaneous tumors, and, according to the literature, chemically induced tumors.
Insights
Polyoma virus-induced tumors exhibit consistent isozyme profiles unique to their histotype, distinguishing them from other tumor types. This uniformity contrasts with variations seen in mammary tumor virus-associated and spontaneous tumors.
Area of Science:
- Biochemistry
- Oncology
- Virology
Background:
- Isozyme profiling is a valuable tool for characterizing cellular and neoplastic states.
- Polyoma virus is a DNA tumor virus used to induce various tumors in experimental models.
- Understanding tumor heterogeneity and origins is crucial for cancer research.
Purpose of the Study:
- To investigate the isozyme profiles of polyoma virus-induced tumors across different mouse strains and histotypes.
- To compare isozyme patterns of DNA virus-induced tumors with those of mammary tumor virus-associated and spontaneous tumors.
- To determine if isozyme profiles can serve as unique biomarkers for specific tumor types.
Main Methods:
- Analysis of 32 enzyme systems using isozyme electrophoresis.
- Induction of tumors using two strains of polyoma virus in conventional and athymic mice.
- Histopathological classification of induced and spontaneous tumors.
Main Results:
- Polyoma virus-induced tumors displayed highly constant and histotype-specific isozyme profiles.
- Salivary and mammary tumors shared a common isozyme profile, distinct from other tumor types.
- Five key isozymes (glycerol-3-phosphate dehydrogenase, glyceraldehydephosphate dehydrogenase, lactate dehydrogenase, sorbitol dehydrogenase, alkaline phosphatase) were sufficient to differentiate tumor types.
- Nonpolyoma mammary tumors and spontaneous salivary tumors showed significant variations in isozyme profiles.
Conclusions:
- Uniformity of isozyme phenotype is characteristic of DNA virus-induced tumor transformation in specific cell differentiative states.
- This uniformity is not observed in mammary tumor virus-associated, spontaneous, or chemically induced tumors.
- Isozyme profiling offers a reliable method for distinguishing between different tumor histotypes, particularly those induced by DNA viruses.