Related Experiment Videos
Mouse embryo fibroblasts transformed by activated ras or dominant-negative p53 express cross-reactive tumor rejection
L J Appleman1, J Uyeki, A B Frey
1Department of Cell Biology, New York University Medical Center, NY 10016, USA.
Abstract:
To study the immune response against oncogene-transformed tumors, C3H/HcN mouse embryo fibroblasts (MEF) were transfected with an activated allele of the H-ras proto-oncogene VaII2 and a dominant-negative allele of the murine p53 tumor suppressor gene VaII35. Transformed cell lines were derived and found to be tumorigenic in syngeneic mice. Immunization with irradiated p53 + ras-transformed MEF, but not primary MEF or unrelated syngeneic cells, protected mice from subsequent challenge with live tumor cells. The role of different immune cell subsets in the effector phase of anti-tumor immunity induced by immunization with p53 + ras-transformed MEF was investigated by in vivo antibody depletion experiments. Immunized mice depleted of CD8+ T, NK or B cells were resistant, but depletion of CD4+ T cells rendered mice susceptible to tumorigenic challenge. In contrast to the tumor-specific immune responses mounted against most chemically or UV-induced tumors, a series of independently derived p53 + ras-transformed MEF were cross-reactive in tumor rejection assays. In addition, immunization with C3H-derived L-929 cell lines expressing single gene products H-ras or p53 did not protect mice against tumorigenic challenge with p53 + ras-transformed tumors. However, MEF transformed by expression of either H-ras or p53 were cross-protective in vivo. Our data suggest that the p53 + ras-transformed MEF share tumor rejection antigens which are also induced by single gene transformation of the parental primary cell but are not the products of oncogenic ras or p53 protein.
Insights
Immunizing mice with tumors created by transforming cells with p53 and ras genes protected them from cancer. This protection relied on CD4+ T cells and involved shared tumor antigens, not the oncogenes themselves.
Area of Science:
- Oncology
- Immunology
- Cancer Research
Background:
- Oncogene-induced tumors can elicit immune responses.
- Understanding tumor-specific immunity is crucial for cancer therapy.
Purpose of the Study:
- To investigate the immune response against tumors transformed by oncogenes.
- To identify the immune cells responsible for anti-tumor immunity.
- To explore the nature of tumor rejection antigens.
Main Methods:
- Transfection of mouse embryo fibroblasts (MEF) with H-ras and p53 genes.
- Tumorigenicity assays in syngeneic mice.
- In vivo antibody depletion experiments to assess immune cell roles.
- Tumor rejection assays using independently derived cell lines.
Main Results:
- Immunization with p53 + ras-transformed MEF conferred protection against tumor challenge.
- CD4+ T cells were essential for anti-tumor immunity; CD8+ T cells, NK cells, and B cells were not.
- Independently derived p53 + ras-transformed MEF exhibited cross-reactive tumor rejection.
- Single gene transformation (H-ras or p53) also induced cross-protective immunity.
Conclusions:
- p53 + ras-transformed tumors share cross-reactive tumor rejection antigens.
- These antigens are induced by single gene transformation but are not the oncogenic proteins themselves.
- CD4+ T cells play a critical role in the rejection of these tumors.