LUTEINIZING-HORMONE-RELEASING HORMONE IN UNDIFFERENTIATED AND DIFFERENTIATED SK-N-SH HUMAN NEUROBLASTOMA-CELLS

The presence of luteinizing hormone-releasing hormone (LHRH) in SK-N-S H human neuroblastoma cells was investigated by immunocytochemistry an d enzyme-linked immunosorbent assays of whole cell extracts and cultur e medium. In addition, ribonuclease protection assays were utilized to quantitate LHRH messenger RNA. The expression of LHRH mRNA and LHRH p rotein level was correlated with neuronal differentiation induced by r etinoic acid (RA). In differentiated SK-N-SH cells the LHRH mRNA level as well as the amount of LHRH in cell extracts and cell medium were s ignificantly lower than in differentiated cells. These results suggest that RA affects the expression of LHRH mRNA and the level of LHRH pro tein in SK-N-SH cells. These data show that altering the growth state of the human neuroblastoma SK-N-SH cells toward more neuronal phenotyp e results in a significant decrease in expression of LHRH mRNA and the protein. The ability of RA to induce changes in LHRH at the mRNA and at the peptide levels will allow further study of RA regulation of LHR H at the neuronal level.