Cancer: Monoclonal Proliferation

Monoclonal proliferation refers to proliferation of cells – which all derive from the one cell originally. All cancers have monoclonality, that is, they all derive from the same cell. Originally, there is genetic mutations in some genes (i.e.: protooncogenes, antioncogenes, apoptotic genes, genes for DNA repair) – and this mutated has lost cell cycle regulation – therefore undergoes uncontrolled proliferation ===> new clones. Now it is gnomically unstable, so is vulnerable to another mutation. This newly mutated cell has further cell cycle regulation – therefore further proliferates ===> new clones. In the end, you get numerous subpopulations of tumour cells all derived from the same cell.

Tumour progression is a phenomenon whereby preneoplastic lesions ===> become benign ===> become invasive (malignant). The level of malignancy is acquired over a period of time, where the tumours become more aggressive. We mentioned above that all tumour cells have a monoclonal origin. But, by the time they become clinically evident their constituent cells are heterogenous. This is because, over time, several subpopulations appear and the cells that make up these populations differ with respect to each in terms of their phenotypic characteristics.


All of these subpopulations have differing antigenicity. The most antigenic subpopulation is killed by the host’s immune response, whilst those that are least antigenic survive. Thus, the surviving clones are the most aggressive and the most adapted to invasiveness and adaptation.

Category: Pathology Notes