Control Mechanisms in the Normal and Neoplastic Cell*

Abstract

This review of control mechanisms in normal and malignant tissues was not intended to be exhaustive. Examples were chosen to acquaint the reader with the problems involved and to point out to the oncologist the usefulness of a study of mechanisms controlling macromolecular syntheses. That mechanisms controlling the expression of genetic information are almost universally defective in at least one type of experimental neoplasm, the hepatocellular carcinoma, is to date rather well substantiated. It is possible to explain most or all of these defective controls by an alteration in the lifetime of the messenger RNA (ribonucleic acid) in the neoplastic cell. This alteration in template stability appears to be a heritable change which may be transmitted to daughter cells by a nongenetic mechanism similar to the extra genetic inheritance of surface structure in protozoa. The crucial experiment now suggested by such a theory is to determine whether or not a reversion of the malignant process is experimentally possible in the mammal and, ultimately, in the human patient.