When oncogenes do not cause cancer

Abstract

Environmental cues, not oncogene-induced senescence, may stop melanocytes with an activating mutation in the BRAF gene from turning into melanoma.

Keywords: cancer biology; genetics; genomics; human; melanocytes; melanoma; microRNA; mutation; nevi.

Figure 1.. The influence of external stimuli on melanocytic cell growth.

Healthy melanocyte precursors (light blue cell, top left) differentiate into melanocytes capable of proliferation (light brown cells, top right) under the influence of external signals, which can be mimicked in cell culture by the drug TPA (green arrows). However, when these precursors acquire a mutation in the BRAF gene (pink cell, bottom left), which initially stimulates them to divide, the same external signals ultimately cause them to stop dividing (brown cells, bottom right), through a process involving the upregulation of the production of certain miRNAs (red bar). The resulting collections of cells appear in the skin as pigmented moles.