il\VOLVEMENT OF RETII\OIC ACID II{ - MSpace at the University of ...

AlþTrsns Retlnolc Acld fAfRAl
g€ls Retlnolc Ac¡d (9cRA)
Figure 4: Chemical structure of retinoic acid and its isomers
IV.b.Retinoic acid metabolism
Retinoic acid is considered to be a steady state retinoid that is charactenzedby a
low rate of synthesis, a high rate of tumover and a constant potential for isomerization
Q.{apoli 1996). Retinoic acid levels in embryonic and adult tissues are found to be 10 and
100 times lower than the levels of its parent molecule-retinol (Eppinger et al. 1993; Scott,
Jr. et al. t994; Thaller and Eichele 1990; Torma et .al.
1994). Although the levels of
retinoic acid in plasma were found to be strictly kept at a steady state, the storage forms
of retinol-retinyl esters are the primary pool from which retinol is mobilized and
maintained in rest of the body. Increased utilization of retinoic acid in the treatment of
neoplastic disorders such as acute promyelocytic leukemia (APL) and the increasing
resistance of a number of cancers to retinoic acid treatment has shed a new light in the
35