gambogic-acid and Melanoma

Cutaneous melanoma is the deadliest form of skin cancer, and gambogic acid (GA) exhibits potent anti-melanoma activity. However, clinical application of GA via intravenous injection and oral administration is limited by systemic toxicity and rapid metabolism in the blood. Here, we developed a new, topical route of GA delivery for anti-melanoma activity and reduction of systemic toxicity. The results indicated that the barrier of the stratum corneum (SC) and low diffusion of GA in the hydrophilic viable skin (epidermis and dermis) limited the GA penetration through intact skin. The combination of azone (AZ) and propylene glycol (PG) showed obvious synergistic effects on skin penetration by GA via improving the permeability of the SC and greatly increasing the skin accumulation of GA, thereby forming a high drug concentration in the skin and achieving a topical targeted treatment of melanoma. In addition, GA (AZ-PG) achieved the same anti-melanoma effect via topical delivery as via intravenous injection. Intravenous injection and oral administration of GA induced remarkable pathological changes in various organs in mice, whereas GA was not toxic to various organs or to the skin via topical delivery. These findings indicated that topical administration of GA is an alternative route for melanoma treatment.

Topics: Administration, Cutaneous; Animals; Melanoma; Mice; Skin; Skin Absorption; Skin Neoplasms; Xanthones

Anti-cutaneous melanoma activity of the skin-delivered gambogic acid (GA) has been reported in our previous study. However, it is difficult for GA to diffuse passively through intact skin without any enhancement means. In this study, a combination of chemical enhancers (EN: azone and propylene glycol) and physical ultrasound (US) was used to improve the percutaneous permeation of GA and enhance the anti-melanoma activity. The enhancement effect of the combination of EN and US (EN-US) on GA in vitro and in vivo was studied, and the enhancement mechanism and skin irritation were also evaluated. We showed that the parameters of US application at a constant frequency (30 kHz) with a duty cycle of 100% and intensity of 1.75 W/cm

Topics: Administration, Cutaneous; Animals; Melanoma; Mice; Permeability; Skin; Skin Absorption; Skin Neoplasms; Xanthones

Topics: Animals; Antineoplastic Agents; Cell Line, Tumor; Cell Movement; Cell Proliferation; Cell Survival; Extracellular Signal-Regulated MAP Kinases; Humans; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Melanoma; Melanoma, Cutaneous Malignant; Mice; Neoplasm Invasiveness; Neoplasm Metastasis; Neovascularization, Pathologic; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt; Signal Transduction; Skin Neoplasms; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factor Receptor-2; Xanthones

Malignant melanoma is an aggressive form of cancer which is highly resistant to chemotherapy. We have previously found that gambogic acid (GA), a kind of polyprenylated xanthone, exhibits an antitumour role in melanoma. The study was designed to investigate novel mechanisms of the antitumour effect of GA in melanoma cells and implanted nude mice. Gambogic acid significantly decreased cell viability, increased apoptosis and reduced migration and invasion in A375 cells. In addition, cisplatin-induced cytotoxicity in both A375 and A375/CDDP cells was increased by GA. The expression of miR-199a-3p was increased by GA in A375 cells and implanted tumours, and inhibition of miR-199a-3p significantly prevented GA-induced effect on cell viability, apoptosis, migration, invasion and cisplatin sensitivity in A375 cells. miR-199a-3p mimics reduced tumour weight and volume in vivo and decreased cell viability, increased apoptosis and reduced migration and invasion in vitro. miR-199a-3p expression was decreased in melanoma tissues and cells, as compared with their controls. miR-199a-3p possessed a potential binding site in the 3'-UTR of zinc finger E-box binding homeobox (ZEB1). ZEB1 expression was increased in melanoma tissues and cells, as compared with their controls. ZEB1 and miR-199a-3p expression was negatively correlated in melanoma tissues. The expression of ZEB1 was decreased by GA in A375 cells and implanted tumours, and up-regulation of ZEB1 significantly prevented GA-induced effect on cell viability, apoptosis, migration, invasion and cisplatin sensitivity. Down-regulation of ZEB1 reduced tumour weight and volume in vivo and decreased cell viability, increased apoptosis and reduced migration and invasion in vitro. We identified the important roles of miR-199a-3p and ZEB1 in melanoma and elucidated the tumour suppressor function of miR-199a-3p through inhibition of ZEB1. The results highlight the importance of miR-199a-3p-ZEB1 signalling in antitumour effect of GA in malignant melanoma and provide novel targets for the chemotherapy of melanoma.

Topics: Animals; Antineoplastic Agents; Apoptosis; Blotting, Western; Cell Line, Tumor; Cisplatin; Drug Resistance, Neoplasm; Female; Melanoma; Mice, Inbred BALB C; Mice, Nude; MicroRNAs; Neoplasm Transplantation; Real-Time Polymerase Chain Reaction; Signal Transduction; Xanthones; Zinc Finger E-box-Binding Homeobox 1

Malignant melanoma has high metastatic potential, is highly resistant to chemotherapy, and has a poor survival rate. Gambogic acid (GA), a polyprenylated xanthone extracted from a traditional Chinese medicinal herb, has been proven to exhibit antitumor activity. The present study aimed to investigate the signaling pathways that mediated GA-induced inhibition of human malignant skin melanoma proliferation.. The study was conducted using A375 cells and the corresponding tumor transplanted in nude mice.. Incubation of A375 cells with 1-10 μg/ml GA decreased cell viability and increased apoptosis. GA concentration-dependently increased p66shc expression and intracellular ROS levels. GA also decreased the oxygen consumption rate and the mitochondrial membrane potential (MMP) in A375 cells. Experimental inhibition of p66shc by siRNA suppressed GA-induced increase of ROS, decrease of oxygen consumption rate, MMP and cell viability, whilst suppressing GA-induced increase of apoptosis. GA concentration-dependently upregulated p53 and Bax expression in A375 cells. GA also increased p53-TA-luciferase activity and p53-binding to Bax promoter, which was inhibited by Sip53. Experimental inhibition of p53 with Sip53 blocked GA-induced decrease of the oxygen consumption rate and cell viability, and blocked the increase of apoptosis. In tumor-bearing nude mice, GA notably inhibited tumor growth, and this action was suppressed by N-acetylcysteine (NAC), a potent antioxidant, and by PFT-α, a p53 inhibitor. In A375 tumors transplanted in nude mice, GA increased both p66shc and p53 expression. NAC and PFT-α treatment did not significantly affect p66shc expression in tumors grown in mice treated with GA. In contrast, both NAC and PFT-α treatment inhibited GA-induced p53 expression in mouse tumors.. Results provided novel preclinical insights into the chemotherapeutic use of GA by highlighting the importance of p66shc/ROS-p53/Bax pathways in the antitumor effect of GA in malignant melanoma.

Topics: Acetylcysteine; Animals; Antineoplastic Agents; Apoptosis; bcl-2-Associated X Protein; Benzothiazoles; Cell Line, Tumor; Cell Proliferation; Humans; Male; Melanoma; Membrane Potential, Mitochondrial; Mice; Mice, Nude; Mitochondria; Reactive Oxygen Species; RNA, Small Interfering; Src Homology 2 Domain-Containing, Transforming Protein 1; Toluene; Transplantation, Heterologous; Tumor Suppressor Protein p53; Xanthones

To investigate the effect of a Chinese traditional medicine, gambogic acid (GA), on human malignant melanoma (MM) A375 cells and to study the mechanism of apoptosis induced by GA.. A375 cells were treated with GA at different doses and for different times, and their proliferation and viability were detected by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay. Apoptosis induced by GA in A375 cells was observed by annexin-V/propidium iodide doubling staining flow cytometry assay and Hoechst staining. To further determine the molecular mechanism of apoptosis induced by GA, the changes in expression of Bcl-2 and Bax were detected by real-time reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot, and caspase-3 activity was measured by fluorescence resonance energy transfer (FRET) probe.. After incubation with GA, A375 cell proliferation was dramatically inhibited in a dose-dependent manner. After these cells had been exposed to GA for 24, 36 and 48 h, the IC(50) values were 1.57 +/- 0.05, 1.31 +/- 0.20, and 1.12 +/- 0.19 microg/mL, respectively. Treatment of A375 cells with GA (2.5-7.5 microg/mL) for 36 h resulted in an increased number of early apoptotic cells, which ranged from 27.6% to 41.9%, in a dose-dependent manner, compared with only 3.5% apoptotic cells in the non-GA-treated group. An increase in Bax and decrease in Bcl-2 expression were found by real-time RT-PCR and Western blot. Caspase-3 activity was increased in a dose-dependent manner, observed by FRET probe.. GA can inhibit the proliferation of A375 cells and induce their apoptosis, which may be related to the up-regulation of the Bax/Bcl-2 ratio and caspase-3 activity.

Topics: Apoptosis; bcl-2-Associated X Protein; Caspase 3; Cell Line, Tumor; Cell Survival; Dose-Response Relationship, Drug; Fluorescence Resonance Energy Transfer; Gene Expression Regulation, Neoplastic; Humans; Melanoma; Proto-Oncogene Proteins c-bcl-2; RNA, Messenger; Skin Neoplasms; Xanthones