Harald zur Hausen

Specific Infections as Trigger of Random Mutations - Their Role in Human Colon and Breast Cancers


Abstract

Our own analysis of global epidemiological studies concerning the risk of red meat and dairy product consumption for some common human cancers (e.g. colon and breast) pointed to factors existing in Eurasian dairy cattle. In addition, prolonged breast-feeding protects newborn babies against infections by several infectious agents. Interestingly, reports also described a protective effect for multiparous women in reducing their risk for several cancers (e.g. breast, colon, endometrium). Apparently, specific sugars, occurring selectively in human milk mediate this effect. The uptake of dairy cattle meat or milk during and after the weaning period results in incorporation of N-5-glycolyl-neuraminic acid into glycoproteins of the cell membrane, modifying their properties and rendering the cells susceptible for novel agents.

We analyzed bovine sera and dairy products for candidate agents, potentially infecting and replicating in human cells. A larger number of single-stranded circular DNA molecules were cloned, sequenced and characterized as bovine meat and milk factors (BMMF). Transcription and DNA replication of those tested up to now occurred in specific human cells. 

We analyzed biopsies of colon cancer and its peripheral tissue with monoclonal antibodies directed against the major protein of one subgroup of these factors (BMMF1). Reactive epitopes were present in cells of the lamina propria, surrounding the Lieberkuehn crypts. Since the same foci also reacted with antibodies specific for inflammatory events, this prompted the design of a model of colon and breast carcinogenesis, presently characterized in more detail.


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