Cellular heterochrony and neoplasia.
Neoplastic change in a cell represents a cellular "macroevolutionary' event. Through variation or rearrangement of regulatory genes, neoplastic cells reiterate the expression of normally quiescent ancestral, juvenile, or embryonic traits and behavior at an inappropriate stage in their ontogeny. The author has coined the term 'cellular heterochrony' to illustrate analogic similarities in the molecular modes of evolutionary change of both anaplastic cancer cells and the heterochronic, paedomorphic evolution of organisms. In these pages, anaplasia is considered to be part of a larger biological phenomenon. A theory regarding the role of prolactin and thyroxine in tumourigenesis is presented to explain the atavistic or heterochronic development and possible metamorphosis of retrodifferentiated malignant cells.
D000818:Animals; D002471:Cell Transformation, Neoplastic / Q000648:ultrastructure*; D005786:Gene Expression Regulation; D006801:Humans; D009369:Neoplasms / Q000235:genetics*; D010641:Phenotype; D011388:Prolactin / Q000097:blood; D012641:Selection, Genetic; D013963:Thyroid Hormones / Q000097:blood
D013963:Thyroid Hormones; D011388:Prolactin