Human lung cancer cells and tissues partially recapitulate the homeobox gene expression profile of embryonic lung

The fetal cell features of tumor cells suggest that neoplasia arises through a process of defective ontogeny. Homeobox (HOX) genes code for transcription factors that orchestrate organogenesis patterning and maintain tissue homeostasis. Thus, if detective ontogeny is a mechanism in cancer development, it can be hypothesized that tumor cells should express the HOX genes normally expressed by the embryonic cells of that tissue. Our data herein indicate that some HOX genes, whose expression is normally restricted to pulmonary embryogenesis, are re-expressed in lung cancer cells. However, lung cancer cells also frequently and inappropriately express HOX genes that are not normally expressed in lung tissue, regardless of developmental stage. Thus, whereas re-expression of some of the embryo-specific HOX genes is a common feature of lung cancer, tumors do not faithfully recapitulate the expression pattern of cells that participate in the early stages of lung development.