ABSTRACT
Rabdosia japonica(Burm.f.) Hara var.glaucocalyx(Maxim.) Hara is a traditional Chinese medicine, and is known to have anti-tumor effects. This study aims to investigate the effect of glaucocalyxin A (GLA), a diterpenoids extracted from Glaucocalyx Hara, on apoptosis of glioma cells and its mechanism. This study investigated the molecular signaling mechanism of GLA-induced glioma cell apoptosis by analyzing survival rate of C6 rat glioma cells, cell morphology, colony formation ability, interference ribonucleic acid, polymerase chain reaction, and Western blot. The result showed that in the presentce of GLA, the survival rate of C6 rat glioma cells decreased significantly, while the expression of guanine nucleotide-exchange factor-H1 was up-regulated, causing phosphorylation of extracellular regulated protein kinases proteins and apoptosis. Hence, the mechanism of GLA-induced glioma cell apoptosis was the GEF-H1/ERK pathway.
ABSTRACT
<p><b>OBJECTIVE</b>AIM To establish a drug screening model based on transcriptional regulation of estrogen responsive element (ERE) and use it to screen compounds for discovering new ligands of estrogen receptor (ER) subtypes.</p><p><b>METHOD</b>A recombinant reporter vector pERE-TAL-SEAP was constructed by inserting a synthetic sequence composed of five tandem copies of EREs upstream of promoter of the reporter vector pTAL-SEAP. The pERE-TAL-SEAP and the internal control plasmid pCMV were transiently co-transfected into Hela cells expressing ER subtype or ER subtype, and the effects of pure ER agonists 17estradiol, phytoestrogen genistein and pure ER antagonist ICI182, 780 on reporter gene SEAP expression were observed.</p><p><b>RESULT</b>In the Hela cells expressing ER alpha or ER beta subtype, the expression of SEAP gene were induced in a dose dependent manner by 17-estrodiol with a maximal effect at approximately 10 nmol.L-1 and with EC50 of (80.58 +/- 8.51) pmol.L-1 and (103.90 +/- 5.29) pmol.L-1, respectively, so done by phytoestrogen genistein with a maximal effect at 1 mumol.L-1 and with EC50 of (10.86 +/- 0.75) nmol.L-1 and (39.38 +/- 2.26) nmol.L-1, respectively. The maximal level induced by estrodiol and genistein were about 7-14 fold higher than that of vehicle. The pure antiestrogen ICI182, 780 at concentration of 1 mumol.L-1 completely blocked the inductions of 17-estrodiol and genistein.</p><p><b>CONCLUSION</b>The cellular drug screening model can be established by transfecting reporter vector pERE-TAL-SEAP in Hela cell lines expressing ER alpha or ER beta. The cell lines can be used to screen compounds with estrogenicity by testing SEAP activity in the culture media of cells growing in microtitier wells. The system should provide an efficient model for screening and analyzing the activity of large numbers of ligands of ER.</p>