Oncoantigen
An oncoantigen is a surface or soluble
Features of oncoantigens
Extracellular localization
Localization of oncoantigens outside tumor cells allows recognition by
Support of the neoplastic phenotype
Loss of oncoantigen expression is unlikely, because oncoantigens support tumor growth. Loss of tumor antigen expression is another cause of escape from immune recognition. This occurs because most tumor antigens are not essential for tumor growth. Hence loss of expression does not decrease the fitness of cancer cells. In contrast, downmodulation of molecules like oncogene products, which are essential for tumor growth, would impair tumor cells.
The complete dependence (also called "addiction") of tumor growth from a given gene product can cease if further genetic alterations occur that activate alternative signaling pathways. Thus, the persistence of oncoantigens is not an absolute property, but rather a feature of specific stages of tumor development.
Identification of oncoantigens
The prototypic oncoantigen is
Other molecules fulfilling the definition of oncoantigen are EGFR/HER-1, the
Most tumor antigens are not oncoantigens, either because they are intracellular molecules, like cancer-testis antigen such as MAGE family members, or because they appear to be dispensable without significant alterations of tumorigenicity, like the
Applications of oncoantigens
Prevention of mouse mammary carcinoma with vaccines against
As escape variants are a major cause of failure also in cancer immunotherapy, it is likely that targeting oncoantigens with vaccines or antibodies will have a stronger clinical impact than attempts at targeting other tumor antigens. The problem so far in using vaccines in oncoantigen research is that the vaccines are typically not long lasting. This is because of the heterogeneous nature of cancer cells. Vaccinations may help the immune system locate certain oncoantigens such as . However; cells that evade the immune system begin to populate and thus cause the growth of a more resistant tumor. There is a use of oncoantigens as markers for faster diagnosis of cancer. The oncoantigens presented from cancerous cells can be used in