title: Inhibition of [3H]ponasterone A binding by ecdysone agonists in the intact Kc cell line.
abstract: Inhibition of the binding of [3H]ponasterone A ([3H]PoA) by ecdysone agonists including diacylhydrazines such as RH-5849, tebufenozide (RH-5992) and methoxyfenozide (RH-2485) was examined in intact Drosophila Kc cells. The reciprocal logarithm of the concentration at which there is 50% inhibition of [3H]PoA binding, pIC(50) (M), was determined as the binding activity for all compounds from each concentration-response curve. The order of the activity was PoA>20-hydroxyecdysone>cyasterone>inokosterone>or=makisterone A>methoxyfenozide>or=tebufenozide>ecdysone>RH-5849. The ranking of steroidal ecdysone analogs is consistent with that obtained against Spodoptera Sf-9 cells. Furthermore, in terms of pIC(50), all binding activity for ecdysone analogs, except ecdysone, estimated in the Kc cell line system was significantly higher than that for the Sf-9 cell line system. However, the activity of ecdysone was comparable between Kc and Sf-9 cells. The activity of diacylhydrazine analogs against Kc cells was significantly low compared with that against Sf-9 cells. The potency of methoxyfenozide was 1/200 that of PoA, which showed the highest activity in the Kc cell line system among all compounds tested. The activity of tebufenozide analogs having an n-pentyl or n-hexyl group instead of a 4-ethylphenyl group was similar to that of RH-5849.
authors.affiliation: Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan. naka@kais.kyoto-u.ac.jp
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Nakagawa
authors.forename: Chieka
authors.initials: C
authors.lastname: Minakuchi
authors.forename: Kaoru
authors.initials: K
authors.lastname: Takahashi
authors.forename: Tamio
authors.initials: T
authors.lastname: Ueno
mesh_terms: D000818:Animals; D002460:Cell Line; D004330:Drosophila; D004440:Ecdysone / Q000819:agonists*; D004441:Ecdysterone / Q000031:analogs & derivatives* / Q000378:metabolism*; D015394:Molecular Structure; D018411:Spodoptera; D014316:Tritium
chemical_list: D014316:Tritium; D004440:Ecdysone; D004441:Ecdysterone; C008999:ponasterone A