Human skin expresses growth hormone but not the prolactin gene.

Using sensitive reverse transcriptase-polymerase chain reaction (RT-PCR) methods, we showed the expression of mRNA for growth hormone (GH) but not prolactin (PRL) in whole human skin (normal and basal cell carcinoma (BCC)). These RNAs for PRL and GH were below detectability in human epidermal keratinocytes and in human and hamster malignant melanocytes. This is in agreement with previous studies showing GH gene expression in dermal fibroblasts. GH peptide was not detected (by immunocytochemistry) in human skin specimens (normal and pathologic) in either dermal or epidermal compartments. The mRNA coding for the GH mediator insulin-like growth factor-1 (IGF-1) was detectable in whole skin and in malignant melanocytes. Therefore, in the present investigation of hormonal mediators of the cutaneous (epidermal) response to environmental stress, we have excluded the direct participation of PRL and GH in that reaction. Thus the analogy previously noted between the systemic (central) and skin responses to stress, as represented by cutaneous expression of hypothalamic-pituitary-adrenal axis components, does not extend to other pituitary hormones also involved in that response such as PRL and GH.