Platycodin D induces mitotic arrest in vitro, leading to endoreduplication, inhibition of proliferation and apoptosis in leukemia cells

Abstract

Platycodin D (PD), a major constituent of triterpene saponins in Platycodon grandiflorum, has also become an interesting candidate for cancer chemotherapy; however, little is known about apoptotic mechanisms on cancer cells. We herein investigated the mechanisms that are related to PD-induced antiproliferation and cell death in human leukemia cells (U937, THP-1 and K562 cells). Cell growth was assessed with proliferation assays, cell counting, flow cytometry, phase contrast microscopy and Western blot assay. Microtubule (MT) formation was measured with immunofluorescent staining and in vitro tubulin polymerization assay. Apoptotic effect was analyzed by assessing increase in annexin V-staining and caspase-3 activity. Treatment of synchronized leukemia cells with varying concentrations of PD resulted in significant mitotic arrest and endoreduplication (END) via downregulation of Cdc2/ cyclin B1 and upregulation of wee1 expression, and elevated the Cdk2 protein via downregulation of p21 within 48 hr. We also researched PD's induction of polyploidy through the MT polymerization. Immunofluorescent microscopy and Western blot analysis revealed that PD significantly caused MT polymerization in leukemia cells. We also found that very high concentrations of PD (>200 lM) were required to directly induce MT polymerization in vitro. Finally, PD exposure induced apoptosis in U937 cells through caspase-3-dependent PARP and lamin A cleavage. We conclude that the primary antileukemia activity of PD is induction of endoreduplication and mitotic arrest, as a consequence of suppressing spindle MT dynamics and in promoting apoptosis in human leukemia cells.

Platycodin D exerts anti-tumor efficacy in H22 tumor-bearing mice via improving immune function and inducing apoptosis

“…Prior to this study, an array of evidence has confirmed that PD may induce apoptotic cell death in various cell lines, including HepG2, MDA-MB-231, U937, K562, PC3, and MCF-7 (Tang et al, 2014;Li et al, 2014;Yu and Kim, 2010;Shin et al, 2009;Kim et al, 2008). However, the anti-tumor efficacy in vivo of Fig.…”

“…1), the major active constituent of P. grandiflorum, has received more and more attention due to its pharmaceutical effects, including anti-inflammation (Chung et al, 2008;Zhang et al, 2015), anti-obesity (Zhao et al, 2006), anti-atherosclerosis (Wu et al, 2012), hepatoprotective Li et al, 2015a), and anti-tumor (Luan et al, 2014;Zhao et al, 2015) effects. It is worth mentioning that PD exerts remarkable anti-cancer effects on different kinds of cancer cell lines, including HepG2, MDA-MB-231, U937, K562, PC3, and MCF-7, with main molecular mechanisms such as promoting apoptosis and inhibiting migration and invasion (Tang et al, 2014;Li et al, 2014;Yu and Kim, 2010;Shin et al, 2009;Kim et al, 2008). However, the ability of PD to inhibit the H22 hepatoma tumor in vivo has not been reported, and little is known about the mechanism responsible for its effects.…”

Anti-atherosclerotic Activity of Platycodin D Derived from Roots of <i>Platycodon grandiflorum</i> in Human Endothelial Cells

“…Therefore, the appropriate concentrations of PD were used for the cell experiments, namely 0.10 mg/mL, 0.15 mg/mL and 0.25 mg/mL. Several reports have shown that PD induces apoptosis 8,[11][12][13] in immortalized keratinocytes and leukemia cells at lower concentrations, but we did not study the effect of low concentration PD on apoptosis in endothelial cells. From the previous results of the trypan blue exclusion test and LDH assay, effects of a low concentration of PD on cell status were not obvious.…”

“…3) Among the many compounds that have been isolated from Platycodi Radix, platycodin D has been found to possess the most potent biological activities, including immunological adjuvant, 4) anti-inflammation and immunomodulation, 5,6) a protective effect on ischemia/reperfusion injury in the gerbil hippocampus, 7) induction apoptosis through nuclear factor-κB activation in immortalized keratinocytes, 8) a cholesterol-lowering effect, 9) an antinociceptive profile, 10) an antileukemia activity, 11) benefits in cancer chemotherapy 12,13) and so on. Atherosclerosis is a chronic inflammatory process resulting from increased oxidative stress.…”

Platycodin D, a metabolite of Platycodin grandiflorum, inhibits highly metastatic MDA-MB-231 breast cancer growth in vitro and in vivo by targeting the MDM2 oncogene

“…Platycodin D (PD), a triterpenoid saponin derived from the roots of Platycodin grandiflorum, has been reported to possess a wide rangeof health benefits, such as anti-atherosclerotic (4), anti-inflammatory (5,6), hypocholesterolemic, and anti-obesity effects (7), as well as spermicidal and contraceptive activity (8). Among the various health benefits of PD, anticancer effects have been noted in several cancer cell lines, including lung cancer cells (9), hepatocellular carcinoma cells (10), gastric cancer cells (11), prostate cancer cells (12), and leukemia cells (13,14). PD has also been reported to inhibit the viability of human breast cancer cells in vitro (15)(16)(17).…”