Condition-dependent presence of beta-lipotropin-like peptide in human keratinocytes

This study aimed to characterize the beta-endorphin-immunoreactive material (betaE-IR) detectable in normal human keratinocytes (NHK). The effects of different culturing conditions and UV-irradiation on production of betaE-IR by NHK were assessed by radioimmunoassay and HPLC. All culture systems contained low levels of betaE-IR that was increased in conditioned media after UV-irradiation under certain conditions. NHK grown in nutrient-poor medium contained highest levels of betaE-IR that exhibited beta-lipotropin-like properties after HPLC analysis. The other culturing conditions displayed no authentic betaE-related peptides. Our results indicate that under certain culturing conditions NHK can produce POMC peptides like beta-lipotropin, which can be induced by UV-radiation.