Expression of Nerve Growth Factor–Induced Clone B Subfamily and Pro-opiomelanocortin Gene in Lung Cancer Cell Lines

Nerve growth factor-induced clone B (NGFI-B), Nur-related factor 1, and neuron-derived orphan receptor-1 have structural features of ligand-activated transcriptional regulators and constitute the NGFI-B subfamily within the nuclear receptor superfamily. The NGFI-B subfamily is highly expressed in neuroendocrine organs and regulates the pro-opiomelanocortin (POMC) gene. Small-cell lung cancer (SCLC) is considered to be a neuroendocrine tumor that produces large numbers of polypeptide hormones. In this study we measured the NGFI-B subfamily and POMC messenger RNA (mRNA) levels in various lung-cancer cell lines by means of the quantitative reverse transcription-polymerase chain reaction, and evaluated the correlations between expression of these genes and polypeptide hormone productions. We also examined the effect of antisense oligonucleotide to NGFI-B mRNA on the expression of POMC mRNA. The NGFI-B subfamily and POMC mRNAs were highly expressed in SCLC cell lines. In addition, there were strong correlations between the NGFI-B, POMC genes, and the adrenocorticotropin hormone (ACTH) level. Further, the antisense oligonucleotide significantly suppressed POMC gene expression. We conclude that the NGFI-B subfamily was a significant molecule in SCLC and that the NGFI-B was a positive transcriptional factor for ACTH production.