The broad objective of this application is to investigate the biochemical and molecular mechanisms of retinoid-induced teratogenesis. Natural and synthetic retinoids are useful in the treatment of various dermatological diseases, including basal cell carcinoma, keratoacanthoma and melanoma. Retinoids have been recommended as chemopreventive agents for lung, breast and urinary bladder cancer. All-trans-retinoic acid (Retin-A) has been suggested as an effective anti-wrinkling agent to prevent aging of skin. One of the major undesirable effects of retinoid therapy is their inherent teratological hazard. A number of human malformations have been reported following retinoid use. In this previous grant (HD 21399) the structure-activity relationship of a large number of synthetic retinoids was investigated. The hamster was shown to be a good model for retinoid-induced terata in humans. Synthetic retinoids showed a range of teratogenic potency over four orders of magnitude. This variation, although described by their molecular characteristics, can not be explained on the basis of their pharmacokinetic parameters or placental permeability. A qualitative relationship was observed between teratogenic potency and binding affinity or retinoids to hamster fetal cellular retinoic acid binding protein (CRABP). The extension of these studies to human embryonic CRABP and characterization of retinoid binding to nuclear retinoic acid receptors (RARs) is now proposed. A large number of synthetic retinoids have been procured and arrangements have been made to obtain human embryonal tissue (obtained from life- threatening ectopic pregnancies and collected under an NIH program). The cDNA clones for different nuclear RARs have been obtained. Investigations will be conducted in the hamster model and to a limited extent on human tissues; data would be compared to each other. Binding affinities of retinoids to human CRABP and to hamster and human RARs will be determined. For retinoids modified at the acidic terminal, their free acid congeners will be used. Presence and amount of different nuclear RARs will be investigated in different tissues at different gestational age in embryos of both species by measuring the amount of specific mRNA, by in situ hybridization, and by immunocytochemistry with monoclonal antibodies. Age- and tissue-specific distribution of RARs will be related to distribution of CRABP and different retinoids. Finally, the induction of RARbeta will be investigated after retinoid exposure since the respective gene has a promoter region for its own product. Results are expected to provide a better understanding of retinoid-induced teratogenesis and a possible identification of chemicals with reduced teratogenic potential.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project (R01)
Project #
5R01HD028259-02
Application #
3329854
Study Section
Toxicology Subcommittee 2 (TOX)
Project Start
1991-04-01
Project End
1994-03-31
Budget Start
1992-04-01
Budget End
1993-03-31
Support Year
2
Fiscal Year
1992
Total Cost
Indirect Cost
Name
Utah State University
Department
Type
Schools of Earth Sciences/Natur
DUNS #
City
Logan
State
UT
Country
United States
Zip Code
84322
Colon-Teicher, L S; Dugyala, R R; Sharma, R P (1996) Temporal expression of retinoic acid receptors in hamster fetus during organogenesis and alteration by retinoic acid treatment. Comp Biochem Physiol C Pharmacol Toxicol Endocrinol 114:71-8
Huggenvik, J I; Sharma, R P (1995) Transcriptional activation of a model reporter system by retinoids and retinoic acid receptor isoforms. Pharmacol Toxicol 76:17-22
Kim, Y W; Sharma, R P (1995) Histochemical localization of retinoic acid receptors in the developing hamster fetus. Reprod Toxicol 9:435-47
Sharma, R P; Kim, Y W (1995) Localization of retinoic acid receptors in anterior-human embryo. Exp Mol Pathol 62:180-9
Kim, Y W; Sharma, R P; Li, J K (1994) Characterization of heterologously expressed recombinant retinoic acid receptors with natural or synthetic retinoids. J Biochem Toxicol 9:225-34
Huggenvik, J I; Collard, M W; Kim, Y W et al. (1993) Modification of the retinoic acid signaling pathway by the catalytic subunit of protein kinase-A. Mol Endocrinol 7:543-50
Goettsch, W; Hatori, Y; Sharma, R P (1992) Adjuvant activity of all-trans-retinoic acid in C57Bl/6 mice. Int J Immunopharmacol 14:143-50
Willhite, C C; Jurek, A; Sharma, R P et al. (1992) Structure-affinity relationships of retinoids with embryonic cellular retinoic acid-binding protein. Toxicol Appl Pharmacol 112:144-53