Isolation and characterization of a complementary DNA specific for human aromatase-system cytochrome P-450 mRNA.

A cloned complementary DNA sequence has been isolated from a human placental cDNA library in the bacteriophage expression vector lambda gt11 after screening with polyclonal antibodies against human placental aromatase-system cytochrome P-450 (P-450Arom). A single recombinant clone, lambda hAROM1, was characterized by its ability to generate a beta-galactosidase fusion protein that reacted independently with polyclonal antibodies raised against beta-galactosidase and cytochrome P-450Arom and with monoclonal antibodies specific for cytochrome P-450Arom. The cDNA insert, which was found to be 1.8 kilobases in length, was radiolabeled and used to analyze poly(A)+ RNA isolated from human placenta and total RNA isolated from human adipose stromal cells cultured in the absence or presence of regulatory factors. The radiolabeled cDNA hybridized to several size species of mRNA in both placental and adipose stromal cell RNA fractions. Changes in the levels of adipose stromal cell RNA that hybridized to the cDNA insert were associated with comparable changes in the levels of translatable cytochrome P-450Arom mRNA and aromatase system activity. These findings are indicative that lambda hAROM1 contains DNA sequences complementary to human cytochrome P-450Arom mRNA and are suggestive that regulatory factors affect aromatase activity by altering the transcriptional activity of the cytochrome P-450Arom gene.