title: Comparison of N-(4-hydroxyphenyl)retinamide and all-trans-retinoic acid in the regulation of retinoid receptor-mediated gene expression in human breast cancer cell lines.
abstract: The activities of N-(4-hydroxyphenyl)retinamide [(4-HPR), Fenretinide] and all-trans-retinoic acid (RA) were determined for (a) the inhibition of cell proliferation; (b) the activation of human retinoid receptor-mediated target gene expression; (c) the inhibition of estradiol- and progesterone-induced gene activation in breast cancer cell lines; and (d) the regulation of the expression of tumor suppressor retinoblastoma protein. Similar to RA, both 4-HPR and its active metabolite N-(4-methoxyphenyl)retinamide (4-MPR) effectively impeded the growth of MCF7 and T-47D human breast cancer cell lines, except that 4-HPR also inhibited the proliferation of RA-resistant BT-20 cells. However, when tested in human recombinant retinoic acid receptor (RAR-alpha, RAR-beta, and RAR-gamma)-induced reporter gene assays, RA was much more potent (>100-fold) than either 4-HPR or 4-MPR. 4-HPR induced transcriptional activation through all three RAR subtypes at 1-10microM, while RA showed comparable activity at 10-100microM. Despite the apparent weak interaction at the RAR level, 4-HPR was comparable to RA in the inhibition of both estrogen receptor- and progesterone receptor-mediated transcriptional activation in MCF7 and T-47D cells, respectively. Moreover, similar to RA, 4-HPR and 4-MPR caused marked up-regulation of tumor suppressor retinoblastoma protein in both MCF7 and T-47D cells. Since RA and 4-HPR showed comparable activity in the inhibition of estrogen recptor- and progesterone receptor-induced gene transcription and in the stimulation of retinoblastoma protein expression in MCF7 and T-47D cells, the reduced RAR activation by 4-HPR may result in the lack of hepatic toxicity and therefore the improved therapeutic efficacy relative to RA.
authors.affiliation: Discovery Research, The R.W. Johnson Pharmaceutical Research Institute, Don Mills, Ontario, Canada.
authors.forename: S M
authors.initials: SM
authors.lastname: Kazmi
authors.forename: R K
authors.initials: RK
authors.lastname: Plante
authors.forename: V
authors.initials: V
authors.lastname: Visconti
authors.forename: C Y
authors.initials: CY
authors.lastname: Lau
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D002455:Cell Division / Q000187:drug effects; D005260:Female; D017313:Fenretinide / Q000494:pharmacology*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006801:Humans; D007641:Keratolytic Agents / Q000494:pharmacology*; D018168:Receptors, Retinoic Acid / Q000378:metabolism*; D016160:Retinoblastoma Protein / Q000096:biosynthesis; D000072482:Retinoic Acid Receptor alpha; D015533:Transcriptional Activation; D014212:Tretinoin / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D000097768:Retinoic Acid Receptor gamma
chemical_list: D000970:Antineoplastic Agents; D017313:Fenretinide; D007641:Keratolytic Agents; D018168:Receptors, Retinoic Acid; D016160:Retinoblastoma Protein; D000072482:Retinoic Acid Receptor alpha; D014212:Tretinoin; D000097768:Retinoic Acid Receptor gamma; C000607071:RARA protein, human; C082925:retinoic acid receptor beta