Phenylcyclohexene and phenylcyclohexadiene substituted compounds having retinoid antagonist activity

Design of synthetic retinoids

This chapter has been conceived as an introductory text to aid in the understanding of the key design strategies for the development of synthetic analogs of endogenous retinoids as ligands for the retinoic acid receptors (RARs) and retinoid X receptors (RXRs). The structure and binding characteristics of the endogenous retinoids are first explained to put the main chemical design challenges in context. Existing biochemical and structural data is then used to describe the guiding principles used to develop agonists and antagonists of the RARs and RXRs. In light of the increasing proliferation of biophysical methods that employ fluorescence measurements or molecular tags, we also examine the application of retinoids as probes and the chemical principles required to develop these tools.

Redifferentiation therapy for thyroid cancer

Thyroid tumorigenesis and carcinogenesis accompany progressive loss of thyroid-specific differentiated functions. Some thyroid cancers are or become dedifferentiated, and they become refractory to efficacy-proven conventional therapies such as radioiodine ablation therapy and thyrotropin (TSH)-suppressive therapy. Redifferentiation therapy by either redifferentiating agents or gene transfer of differentiation-related genes may retard tumor growth and make tumors respond to conventional therapies.

The RAIG Family Member, GPRC5D, Is Associated with Hard-Keratinized Structures

Retinoic acid-inducible gene-1 was originally identified as an orphan G-protein coupled receptor induced by retinoic acid. Three highly homologous oGPCR (GPRC5B, GPRC5C, and GPRC5D) have since been classified into the RAIG1 family. We describe here, the unique tissue distribution of GPRC5D and its mechanism of expression. Hybridization in situ has shown that GPRC5D is expressed in differentiating cells that produce hard keratin, including cortical cells of the hair shaft, the keratogenous zone of the nail, and in a central region of the filiform papillae of the tongue. The GPRC5D transcript is expressed in hair follicles during mid- and late anagen, and catagen but not at telogen and early anagen phases. The differentiation-inducer, all-trans retinoic acid, induces GPRC5D expression in cultured hair bulb cells. Because the tissue distribution of GPRC5D indicates a relationship with hard keratins that constitute the major structural proteins of hard epithelial tissues, we investigated the effect of GPRC5D on acid hard keratins. Analyses of cultured cells showed that transient overexpression resulted in suppression of Ha3 and stimulation of Ha4 hair keratin gene expression. The expression was maintained in the hair follicles of whn-deficient (nude) mice, suggesting that this gene is regulated by a signal pathway different from that of hair keratin synthesis. Collectively, these data provide a framework for understanding the molecular mechanisms of GPRC5D function in hard keratinization.