Dissection of stromal and cancer cell-derived signals in melanoma xenografts before and after treatment with DMXAA.

Dissection of stromal and cancer cell-derived signals in melanoma xenografts before and after treatment with DMXAA.

Br J Cancer. 2012 Mar 13;106(6):1134-47

Authors: Henare K, Wang L, Wang LC, Thomsen L, Tijono S, Chen CJ, Winkler S, Dunbar PR, Print C, Ching LM

Abstract

BACKGROUND: The non-malignant cells of the tumour stroma have a critical role in tumour biology. Studies dissecting the interplay between cancer cells and stromal cells are required to further our understanding of tumour progression and methods of intervention. For proof-of-principle of a multi-modal approach to dissect the differential effects of treatment on cancer cells and stromal cells, we analysed the effects of the stromal-targeting agent 5,6-dimethylxanthenone-4-acetic acid on melanoma xenografts.

METHODS: Flow cytometry and multi-colour immunofluorescence staining was used to analyse leukocyte numbers in xenografts. Murine-specific and human-specific multiplex cytokine panels were used to quantitate cytokines produced by stromal and melanoma cells, respectively. Human and mouse Affymetrix microarrays were used to separately identify melanoma cell-specific and stromal cell-specific gene expression.

RESULTS: 5,6-Dimethylxanthenone-4-acetic acid activated pro-inflammatory signalling pathways and cytokine expression from both stromal and cancer cells, leading to neutrophil accumulation and haemorrhagic necrosis and a delay in tumour re-growth of 26 days in A375 melanoma xenografts.

CONCLUSION: 5,6-Dimethylxanthenone-4-acetic acid and related analogues may potentially have utility in the treatment of melanoma. The experimental platform used allowed distinction between cancer cells and stromal cells and can be applied to investigate other tumour models and anti-cancer agents.

PMID: 22415295 [PubMed - indexed for MEDLINE]

pubmed: xanthones research

Alterations in Cell Cycle and Induction of Apoptotic Cell Death in Breast Cancer Cells Treated with ?-Mangostin Extracted from Mangosteen Pericarp.

Alterations in Cell Cycle and Induction of Apoptotic Cell Death in Breast Cancer Cells Treated with ?-Mangostin Extracted from Mangosteen Pericarp.

J Biomed Biotechnol. 2012;2012:672428

Authors: Kurose H, Shibata MA, Iinuma M, Otsuki Y

Abstract

The development of molecularly targeted drugs has greatly advanced cancer therapy, despite these drugs being associated with some serious problems. Recently, increasing attention has been paid to the anticancer effects of natural products. ?-Mangostin, a xanthone isolated from the pericarp of mangosteen fruit, has been shown to induce apoptosis in various cancer cell lines and to exhibit antitumor activity in a mouse mammary cancer model. In this study, we investigated the influence of ?-mangostin on apoptosis and cell cycle in the human breast cancer cell line MDA-MB231 (carrying a p53 mutation, and HER2, ER, and PgR negative) in order to elucidate its anticancer mechanisms. In ?-mangostin-treated cells, induction of mitochondria-mediated apoptosis was observed. On cell-cycle analysis, G1-phase arrest, increased p21(cip1) expression and decreases in cyclins, cdc(s), CDKs and PCNA were observed. In conclusion, ?-mangostin may be useful as a therapeutic agent for breast cancer carrying a p53 mutation and having HER2- and hormone receptor-negative subtypes.

PMID: 22577295 [PubMed - in process]

pubmed: mangosteen

Solid dispersions of ?-mangostin improve its aqueous solubility through self-assembly of nanomicelles.

Solid dispersions of ?-mangostin improve its aqueous solubility through self-assembly of nanomicelles.

J Pharm Sci. 2012 Feb;101(2):815-25

Authors: Aisha AF, Ismail Z, Abu-Salah KM, Majid AM

Abstract

?-Mangostin is an oxygenated heterocyclic xanthone with remarkable pharmacological properties, but poor aqueous solubility and low oral bioavailability hinder its therapeutic application. This study sought to improve the compound’s solubility and study the mechanism underlying solubility enhancement. Solid dispersions of ?-mangostin were prepared in polyvinylpyrrolidone (PVP) by solvent evaporation method and showed substantial enhancement of ?-mangostin’s solubility from 0.2 ± 0.2 ?g/mL to 2743 ± 11 ?g/mL. Fourier transform infrared spectroscopy and differential scanning calorimetry indicated interaction between ?-mangostin and PVP. Transmission electron microscopy and dynamic light scattering showed self-assembly of round anionic nanomicelles with particle size in the range 99-127 nm. Powder X-ray diffraction indicated conversion of ?-mangostin from crystalline into amorphous state, and scanning electron microscopy showed the presence of highly porous powder. Studies using the fluorescent probe pyrene showed that the critical micellar concentration is about 77.4 ± 4 ?g/mL. Cellular uptake of nanomicelles was found to be mediated via endocytosis and indicated intracellular delivery of ?-mangostin associated with potent cytotoxicity (median inhibitory concentration of 8.9 ± 0.2 ?g/mL). Improved solubility, self-assembly of nanomicelles, and intracellular delivery through endocytosis may enhance the pharmacological properties of ?-mangostin, particularly antitumor efficacy.

PMID: 22081501 [PubMed - indexed for MEDLINE]

pubmed: xanthones research

Solid dispersions of ?-mangostin improve its aqueous solubility through self-assembly of nanomicelles.

Solid dispersions of ?-mangostin improve its aqueous solubility through self-assembly of nanomicelles.

J Pharm Sci. 2012 Feb;101(2):815-25

Authors: Aisha AF, Ismail Z, Abu-Salah KM, Majid AM

Abstract

?-Mangostin is an oxygenated heterocyclic xanthone with remarkable pharmacological properties, but poor aqueous solubility and low oral bioavailability hinder its therapeutic application. This study sought to improve the compound’s solubility and study the mechanism underlying solubility enhancement. Solid dispersions of ?-mangostin were prepared in polyvinylpyrrolidone (PVP) by solvent evaporation method and showed substantial enhancement of ?-mangostin’s solubility from 0.2 ± 0.2 ?g/mL to 2743 ± 11 ?g/mL. Fourier transform infrared spectroscopy and differential scanning calorimetry indicated interaction between ?-mangostin and PVP. Transmission electron microscopy and dynamic light scattering showed self-assembly of round anionic nanomicelles with particle size in the range 99-127 nm. Powder X-ray diffraction indicated conversion of ?-mangostin from crystalline into amorphous state, and scanning electron microscopy showed the presence of highly porous powder. Studies using the fluorescent probe pyrene showed that the critical micellar concentration is about 77.4 ± 4 ?g/mL. Cellular uptake of nanomicelles was found to be mediated via endocytosis and indicated intracellular delivery of ?-mangostin associated with potent cytotoxicity (median inhibitory concentration of 8.9 ± 0.2 ?g/mL). Improved solubility, self-assembly of nanomicelles, and intracellular delivery through endocytosis may enhance the pharmacological properties of ?-mangostin, particularly antitumor efficacy.

PMID: 22081501 [PubMed - indexed for MEDLINE]

pubmed: xanthones research

Photosensitized xanthone-based oxidation of guanine and its repair: a laser flash photolysis study.

Photosensitized xanthone-based oxidation of guanine and its repair: a laser flash photolysis study.

J Photochem Photobiol B. 2011 Nov 3;105(2):157-61

Authors: Tang R, Zhang P, Li H, Liu Y, Wang W

Abstract

The photosensitized oxidation of guanine (G) by the triplet state of xanthone (XT) and the repair for photo-damaged G(-H)(·) by ferulic acid (FCA) were investigated using the laser flash photolysis technique. The rate constants of the reaction of triplet state of XT with G and with FCA were determined as 4.5×10(9) and 8.0×10(9) L mol(-1) s(-1), respectively. Laser exposure was performed on the N(2)-saturated acetonitrile/water (v/v, 1:1) solution containing G, XT and FCA. The transient absorption spectra indicated that the triplet state of XT first reacted with G predominantly to form the oxidized radical G(-H)(·). The radical G(-H)(·) was rapidly repaired by FCA, and the rate constant for the repair reaction was determined as 1.1×10(9) L mol(-1) s(-1). These results demonstrated that non-enzymatic repair is a feasible method for repairing photosensitized DNA bases oxidation.

PMID: 21908198 [PubMed - indexed for MEDLINE]

pubmed: xanthones research