?-Opioid receptor binding varies inversely with tumor grade in human gliomas

BACKGROUND Opioid agonists can inhibit cell proliferation in various neural tumor cell lines, including rat gliomas. Because opioid antimitogenic effects are mediated by opioid receptors, it was of interest to the authors to determine opioid receptor levels in human brain tumors. METHODS Specimens obtained at craniotomy from 30 patients with glioma and nonneoplastic brain disorders were evaluated for their κ-opioid receptor binding. Kd and Bmax values were estimated from homologous competition binding curves with the κ1-selective radioligand [3H]U69,593. RESULTS Receptor binding density was greatest in nonneoplastic brain tissue, less in Grade 2 and 3 astrocytoma, and least in glioblastoma multiforme. CONCLUSIONS These results suggest that opioid receptor-based stratification of grade may have clinical utility in distinguishing glioblastoma multiforme from lower grade astrocytomas, and thereby may facilitate diagnosis and treatment. Cancer 1998;83:2561-2566. © 1998 American Cancer Society.