The author deals with mechanisms of paraneoblastic hormone production. Paraneoblastic production of protein hormones is closely linked with processes of malignant transformation of cells which takes place as a result of dysregulation of hyperactive c-oncogens. Products of these oncogens either directly code growth factors or form their receptors or the receptors of dijerent hormones. The product of the family of c-ras-oncogens creates by excessive formation of G-proteins an excessively long activation of adenyl cyclase by hormones which act via cAMP. Under the influence of c-oncogens proliferating and differentiating stem cells reach in larger amounts the APUD stage of differentiation, where they express their genes for the formation of the entire range of protein hormones. Their ectopic formation may acquire biological or clinical significance, as relatively many cells remain in the APUD stage of differentiation, if the process of postscriptional adjustment of the formed hormones is not impaired.

Keywords: Cell Transformation, Neoplastic; Hormones, Ectopic /metabolism/; Humans; Oncogenes; Paraneoplastic Syndromes /genetics/