[Ectopic hormone production and gene expression in tumors]

Recent progress in research into ectopic hormone production and hormone gene expression in tumors is reviewed. Biochemical, immunochemical and morphological studies have shown that differentiation between "ectopic" and "eutopic" has become difficult and that the types of peptide hormones, neural peptides and growth factors produced, their molecular heterogeneities and ability of plural hormone production are greatly different in each tumor. Recently, the gene structures of many hormones and amino acid sequences of hormone precursors have been determined by genetic recombination techniques. However, the nature of hormone genes, the mechanism of gene expression and the processing mechanisms of hormone precursors in normal and tumor cells remain to be studied.