Gambogic acid synergistically potentiates cisplatin-induced apoptosis in non-small-cell lung cancer through suppressing NF-κB and MAPK/HO-1 signalling
L-H Wang1,2, Y Li1, S-N Yang1, F-Y Wang1, Y Hou1, W Cui1, K Chen1, Q Cao1, S Wang1, T-Y Zhang1, Z-Z Wang2, W Xiao2, J-Y Yang1 and C-F Wu1
1Department of Pharmacology, Shenyang Pharmaceutical University, Shenyang 110016, People’s Republic of China
2Jiangsu Kanion Pharmaceutical Co. Ltd, Lianyungang 222001, People’s Republic of China
Background: Gambogic acid (GA) has been reported to have potent anticancer activity and is authorised to be tested in phase II clinical trials for treatment of non-small-cell lung cancer (NSCLC). The present study aims to investigate whether GA would be synergistic with cisplatin (CDDP) against the NSCLC.
Methods: 1-(4,5-Dimethylthiazol-2-yl)-3,5-diphenylformazan (MTT), combination index (CI) isobologram, western blot, quantitative PCR, flow cytometry, electrophoretic mobility shift assay, xenograft tumour models and terminal deoxynucleotide transferase-mediated dUTP nick-end labelling analysis were used in this study.
Results: The cell viability results showed that sequential CDDP-GA treatment resulted in a strong synergistic action in A549, NCI-H460, and NCI-H1299 cell lines, whereas the reverse sequence and simultaneous treatments led to a slight synergistic or additive action. Increased sub-G1 phase cells and enhanced PARP cleavage demonstrated that the sequence of CDDP-GA treatment markedly increased apoptosis in comparison with other treatments. Furthermore, the sequential combination could enhance the activation of caspase-3, -8, and 9, increase the expression of Fas and Bax, and decrease the expression of Bcl-2, survivin and X-inhibitor of apoptosis protein (X-IAP) in A549 and NCI-H460 cell lines. In addition, increased apoptosis was correlated with enhanced reactive oxygen species generation. Importantly, it was found that, followed by CDDP treatment, GA could inhibit NF-κB and mitogen-activated protein kinase (MAPK)/heme oxygenase-1 (HO-1) signalling pathways, which have been validated to reduce ROS release and confer CDDP resistance. The roles of NF-κB and MAPK pathways were further confirmed by using specific inhibitors, which significantly increased ROS release and apoptosis induced by the sequential combination of CDDP and GA. Moreover, our results indicated that the combination of CDDP and GA exerted increased antitumour effects on A549 xenograft models through inhibiting NF-κB, HO-1, and subsequently inducing apoptosis.
Conclusion: Gambogic acid sensitises lung cancer cells to CDDP in vitro and in vivo in NSCLC through inactivation of NF-κB and MAPK/HO-1 signalling pathways, providing a rationale for the combined use of CDDP and GA in lung cancer chemotherapy. Source : British Journal of Cancer Link to Full Article
Study of the enhanced anticancer efficacy of gambogic acid on Capan-1 pancreatic cancer cells when mediated via magnetic Fe3O4 nanoparticles
Gambogic acid (GA), a potent anticancer agent, is limited in clinical administration due to its poor water solubility. The aim of this study was to explore a drug delivery system based on magnetic Fe3O4 nanoparticles (MNP-Fe3O4) conjugated with GA to increase water solubility of the drug and enhance its chemotherapeutic efficiency for pancreatic cancer.
Methods GA was conjugated with the MNP-Fe3O4 colloidal suspension by mechanical absorption polymerization to construct GA-loaded MNP-Fe3O4, which acted as a drug delivery system.
Results Combination therapy with GA and MNP-Fe3O4 induced remarkable improvement in anticancer activity, which was demonstrated by optical microscopic observations, MTT assay, and nuclear DAPI staining. Furthermore, the possible signaling pathway was explored by Western blot. In Capan-1 pancreatic cancer cells, our observations demonstrated that this strategy could enhance potential anticancer efficiency by inducing apoptosis. The mechanisms of the synergistic effect may be due to reducing protein expression of Bcl-2 and enhancing that of Bax, caspase 9, and caspase 3.
Conclusion These findings demonstrate that a combination of GA and MNPs-Fe3O4 represents a promising approach to the treatment of pancreatic cancer.
A role for transferrin receptor in triggering apoptosis when targeted with gambogic acid
Shailaja Kasibhatla,*† Katayoun A. Jessen,* Sergei Maliartchouk,* Jean Yu Wang,* Nicole M. English,* John Drewe,* Ling Qiu,* Shannon P. Archer,* Anthony E. Ponce,* Nilantha Sirisoma,* Songchun Jiang,* Han-Zhong Zhang,* Kurt R. Gehlsen,* Sui Xiong Cai,* Douglas R. Green,‡ and Ben Tseng*
Note - Gambogic acid is a xanthonoid that is derived from the brownish or orange resin from Garcinia hanburyi
Abstract Transferrin receptor (TfR) has been shown to be significantly overexpressed in different types of cancers. We discovered TfR as a target for gambogic acid (GA), used in traditional Chinese medicine and a previously undiscovered link between TfR and the rapid activation of apoptosis. The binding site of GA on TfR is independent of the transferrin binding site, and it appears that GA potentially inhibits TfR internalization. Down-regulation of TfR by RNA interference decreases sensitivity to GA-induced apoptosis, further supporting TfR as the primary GA receptor. In summary, GA binding to TfR induces a unique signal leading to rapid apoptosis of tumor cells. These results suggest that GA may provide an additional approach for targeting the TfR and its use in cancer therapy.
Discussion ...These results report the identification and characterization of a molecule (GA) that specifically targets TfR engaging a previously unreported mechanism of action to induce apoptosis. It appears from this body of work that GA interferes with TfR internalization leading to the initial, and rapid, signal for apoptosis. We also demonstrate that GA and Tf bind to independent sites on the receptor, and it appears that GA is not competed by Tf. These studies also suggest a requirement of GA for TfR-mediated rapid apoptosis because the mere down-regulation of TfR does not activate this pathway. Whether GA causes additional conformational changes in the receptor, thereby recruiting the death machinery in an unprecedented manner, remains to be uncovered.
With our continuing efforts, we suggest that the GA/TfR discovery may lead to a new generation of anti-cancer drugs and targeting mechanisms that will be synergistic with existing treatments. Identifying roles for other adaptor proteins or signaling molecules in this GA-induced TfR pathway will possibly identify additional therapeutic targets.