Spontaneous mutation, defined

Some established cell lines were derived from malignant tissue. Many of these cell lines can form tumors when injected into susceptible animals. Other established cell lines are not Uunorigenic. However, exposure to carcinogens, and irradiation can cause these cells to form tumors in susceptible animals. In addition, transformation can be caused by spontaneous mutations, by growth factors, and by viral (or oncogenic) transformation (Table 6). Malignant transformation is defined as consisting of the series of events that cause normal cells to develop the capacity to form tumors. 

Bt ML, Ginsbeig MH,FrelingerAL,in, Bemdt MC, Loftus 1C A spontaneous mutation of int rinan,b, (platelet glycoprotein llb-IIIa) helps define a ligand binding site 1 Biol Chem 267 3789-3794,1992. 

Overall, these data raise the possibility that most of the mutations in breast cancer might have a spontaneous origin, but that a small proportion of them bear signatures that suggest the involvement of exogenous carcinogens such as those present in tobacco smoke. These proposals await scrutiny by the analysis of large cohorts with defined exposure histories. 

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