Objective: Retinoic acid plays an essential role in epithelial differentiation, and retinoid homeostasis is disrupted in cancers of epithelial origin. The goal of this study was to determine whether hRoDH-4, an enzyme that can catalyze the first and rate-limiting step in retinoic acid biosynthesis, is expressed in normal endometrium and, if so, whether its expression is altered in endometrial cancer.
Study design: Proliferative, secretory, hyperplastic, and neoplastic endometria were examined by immunocytochemistry for hRoDH-4 protein and by reverse transcriptase-polymerase chain reaction for the hRoDH-4 transcript.
Results: In proliferative and secretory glandular epithelia, immunoreactive hRoDH-4 was uniformly present. In endometrial cancers, hRoDH-4 immunoreactivity was markedly reduced in many neoplastic epithelial cells. Expression of hRoDH-4 in normal and neoplastic endometrium was confirmed by findings on reverse transcriptase-polymerase chain reaction.
Conclusion: These findings are consistent with the hypothesis that altered expression of enzymes essential for in situ retinoic acid biosynthesis is an important phenotypic change associated with the development of endometrial cancer.