Mouse embryo fibroblasts transformed by activated ras or dominant‐negative p53 express cross‐reactive tumor rejection antigens

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.

CD8+ Tumor-Infiltrating T Cells Are Deficient in Perforin-Mediated Cytolytic Activity Due to Defective Microtubule-Organizing Center Mobilization and Lytic Granule Exocytosis

“…For these analyses we studied two tumors, a fibrosarcoma made by expression of cDNAs encoding dominant-negative p53 plus activated Ha-ras genes in primary embryonic fibroblasts termed 6-1 (15), and separately a chemically induced adenocarcinoma, MCA-38 (13). For all experiments data achieved with either tumor were highly similar if not identical and representative data is shown.…”

Targeting of Several Glycolytic Enzymes Using RNA Interference Reveals Aldolase Affects Cancer Cell Proliferation through a Non-glycolytic Mechanism

“…Dominant-negative p53-transformed Rat1 fibroblast (DN-p53 Rat1) (29), rat 9L glioblastoma, and rat PC-12 pheochromocytoma cells all form tumors when injected into animals (29 -31). Each of these cell lines was transfected with the same aldolase siRNAs as were used for Ras-3T3 cells.…”

CD8+ Tumor-Infiltrating Lymphocytes Are Primed for Fas-Mediated Activation-Induced Cell Death But Are Not Apoptotic In Situ

“…The properties of this tumor have been described previously (21). MCA-38 adenocarcinoma was the gift of Y. Liu (Ohio State University, Columbus, OH).…”

“…For these analyses, we studied two tumors, a fibrosarcoma made by expression of cDNAs encoding dominant-negative p53 plus activated Ha-ras genes in primary embryonic fibroblasts termed "6-1" (21,22), and, separately, a chemically induced adenocarcinoma, MCA-38 (24). For all experiments, data achieved with either tumor were highly similar, if not identical, and representative data is shown.…”