Stability of anticancer activity induced by cellular differentiation.
Human and murine cells can express anticancer activity which we define as any biologic process that can prevent or inhibit the expression of the transformed phenotype. The existence of anticancer activities has been demonstrated by many systems, including the fusion of normal cells with tumorigenic cells and the implantation of cancer cells into specific embryonic sites. Furthermore, cellular differentiation has recently been shown to regulate the expression of anticancer activity without limiting a cell's proliferative potential. Those results show that reversible nonterminal differentiation (NTD) induces 3T3T mesenchymal stem cells to become resistant to transformation by physical or chemical carcinogens or oncogene products and NTD induces spontaneously transformed 3T3T cells to revert to a benign state and to become resistant to retransformation. In addition, NTD induces SV40 T-antigen transformed 3T3T cells to revert to a nontransformed state that prevents growth in soft agarose. Data are now presented that define the relative stability of these differentiation-induced anticancer activities. Anticancer activity induced by NTD in 3T3T cells is shown to have a mean stability of 55 population doublings (PD) and a maximum stability of 88 PD. Anticancer activity induced by NTD in spontaneously transformed 3T3T cells shows a similar stability with a mean of 55 PD and a maximum of 95 PD. Finally, in SV40-3T3T cells, the induction of NTD suppresses soft agarose growth for a maximum of 20-30 PD. These results demonstrate that three forms of differentiation-induced anticancer activity are stable for an extended number of population doublings.
Maercklein
P B
PB
Section of Experimental Pathology, Mayo Clinic/Foundation, Rochester, Minnesota.
Estervig
D N
DN
Scott
R E
RE
D000818:Animals; D002454:Cell Differentiation / Q000235:genetics*; D002471:Cell Transformation, Neoplastic; D006801:Humans; D051379:Mice; D009365:Neoplasm Regression, Spontaneous; D014411:Neoplastic Stem Cells; D010641:Phenotype; D014407:Tumor Cells, Cultured