Proenkephalin A-like mRNA in human leukemia leukocytes and CNS-tissues.

Total RNA has been prepared from human leukocytes from patients with chronic lymphoblastic leukemia (CLL) as well as from post mortem human caudate nucleus, hypothalamus, cerebellum and cerebral cortex. Dot-blot and Northern blot analysis, using a human proenkephalin A clone and SP-6 derived "complementary" proenkephalin A RNA respectively, revealed the existence of proenkephalin A-like RNA:s in CLL-leukocytes with the same characteristics as in caudate nucleus, hypothalamus, and cortex. Furthermore, RIA and Western blot analysis confirmed that immunoreactive pro-enkephalin A activity is present in human CLL-leukocytes. The progress in DNA recombinant technology has allowed the study of opioid peptide regulation at the transcriptional and translational-posttranslational level. Studies on the distribution and quantitation of preproenkephalin A mRNA in bovine, rat and human central nervous system (CNS) have recently been reported. Different opioid peptides, related to the enkephalins, dynorphins and beta-endorphin have also been detected in tissues outside the CNS including the adrenal medulla and in pheochromocytomas. Northern blot analysis and cDNA-cloning confirmed that the proenkephalin A gene is indeed expressed in these tissues. Proenkephalin A derived peptides are potentially significant in nervous disorders. We have chosen to investigate whether the corresponding gene is expressed not only in CNS-tissues but also in human leukocytes, cells readily obtained in individual patients.