Anti-microtubule activity of tubeimoside I and its colchicine binding site of tubulin

Abstract

Background Tubeimoside I (TBMS1) was isolated from the tubers of Bolbostemma paniculatum (Maxim.) Franquet. TBMS1 shows potent anti-tumor activity. The present study was conducted to investigate the anti-microtubule role of TBMS1 and its binding site of tubulin. Methods Cell growth inhibition was measured by MTT after treatment with TBMS1. Uptake kinetics of TBMS1 by human nasopharyngeal carcinoma CNE-2Z cell line (CNE-2Z) was assayed by HPLC. Microtubule protein (MTP) was prepared from porcine brain through two cycles of polymerization-depolymerization in a high molarity buffer. Inhibition of MTP polymerization induced by TBMS1 was determined by a turbidity measurement and a sedimentation assay; the interactions of TBMS1 with tubulin within CNE-2Z cells were investigated by immunofluorescence microscopy and immunoblotting. TBMS1 was tested for its ability to inhibit binding of known tubulin ligands through competitive binding assay. Results TBMS1 displayed growth inhibitory activity against CNE-2Z cells with IC 50 value of 16.7 lM for 72 h. HPLC analysis of TBMS1 uptake by CNE-2Z cells displayed the initial slow TBMS1 uptake and then gradually reaching an maximum uptake near 18 h. CNE-2Z cells treated with TBMS1 (25 lM, 3 h) were sufficient to cause the microtubular network disruption. Immunoblot analysis showed that the proportion of cytosolic tubulin of cells treated with TBMS1 increased in a time-and concentration-dependent manner. TBMS1 did not inhibit the binding of vinblastine to tubulin. Colchicine binding to tubulin was inhibited in the presence of TBMS1. Conclusions TBMS1 is an anti-microtubule agent, and its binding site of tubulin is the colchicine binding site of tubulin.

Tubeimoside-1 inhibits growth via the induction of cell cycle arrest and apoptosis in human melanoma A375 cells

“…Furthermore, the cells become round-shaped and poorly adhered to the cultured plates while the control group cells showed a typical polygonal and cobblestone monolayer appearance and remained firmly attached to cultured plates (data not shown). The results indicated that TBMS1 induced growth inhibition of A375 cells, in addition to other type of cancer cells previously reported including A549 lung cancer cells (Zhang et al, 2011), HeLa cervical cancer cells (Xu et al, 2009), and nasopharyngeal carcinoma CNE-2Z (Ma et al, 2008;Weng et al, 2003).…”

“…Tubeimoside-1 (TBMS1), a triterpenoid saponin has been reported to have wide spectrum of biological effects, including anti-inflammatory, anti-tumorigenic and anti-HIV activities (Yu et al, 1994;Yu et al, 1992). Furthermore, TBMS1 has anti-proliferative effect and induced apoptosis in cancer cells such as lung cancer (Zhang et al, 2011), cervical cancer (Xu et al, 2009), nasopharyn-geal carcinoma (Ma et al, 2008;Weng et al, 2003) and leukemia HL-60 cells (Yu et al, 1996). However, the cytotoxic effects of TBMS1 on melanoma and its mechanism were still unknown.…”

The novel Akt inhibitor Palomid 529 (P529) enhances the effect of radiotherapy in prostate cancer

“…The method was performed according to earlier publications (Ma et al, 2007). Each 0.5 ml reaction contained 0.1 M MES (pH 7.0 with NaOH in 1 M stock solution), 0.5 mM MgCl 2 , 1 mM of tubulin [ 3 H]colchicine (5 mM), and the indicated concentration of different drugs (1 and 5 mM combretastatin A-4-phosphate (CA4P); 5 and 50 mM 2-methoxyestradiol (2ME 2 ); 5 and 50 mM P529).…”

Induction of apoptosis through tubulin inhibition in human cancer cells by new chromene-based chalcones

“…The assay was carried out based on previous procedures with some modifications (Ma et al, 2008). Briefly, a drug/DMSO-tubulin preincubation, without GTP, was performed for 15 min at 0°C in ice.…”