Arsenic Disulfide Combined with L-Buthionine-(S, R)-Sulfoximine Induces Synergistic Antitumor Effects in Two-Dimensional and Three-Dimensional Models of MCF-7 Breast Carcinoma Cells.

Three-dimensionally (3D) cultured tumor cells (spheroids) exhibit more resistance to therapeutic agents than the cells cultured in traditional two-dimensional (2D) system (monolayers). We previously demonstrated that arsenic disulfide (As2S2) exerted significant anticancer efficacies in both 2D- and 3D-cultured MCF-7 cells, whereas 3D spheroids were shown to be resistant to the As2S2 treatment. L-buthionine-(S, R)-sulfoximine (BSO), an inhibitor of glutathione (GSH) synthesis, has been regarded to be a potent candidate for combinatorial treatment due to its GSH modulation function. In the present study, we introduced BSO in combination with As2S2 at a low concentration to investigate the possible enhancing anticancer efficacy by the combinatorial treatment on 2D- and 3D-cultured MCF-7 cells. Our results presented for the first time that the combination of As2S2 and BSO exerted potent anticancer synergism in both MCF-7 monolayers and spheroids. The IC50 values of As2S2 in combinatorial treatment were significantly lower than those in treatment of As2S2 alone in both 2D- and 3D-cultured MCF-7 cells (P<0.01, respectively). In addition, augmented induction of apoptosis and enhanced cell cycle arrest along with the regulation of apoptosis- and cell cycle-related proteins, as well as synergistic inhibitions of PI3K/Akt signals, were also observed following co-treatment of As2S2 and BSO. Notably, the combinatorial treatment significantly decreased the cellular GSH levels in both 2D- and 3D-cultured MCF-7 cells in comparison with each agent alone (P<0.05 in each). Our results suggest that the combinatorial treatment with As2S2 and BSO could be a promising novel strategy to reverse arsenic resistance in human breast cancer.

Plant-derived alkaloid sinomenine potentiates glucocorticoid pharmacodynamics in mitogen-activated human peripheral blood mononuclear cells by regulating the translocation of glucocorticoid receptor.

Sinomenine has been used as an antirheumatic drug in China. Glucocorticoid combined with sinomenine could be an alternative therapeutic approach. In this study, we evaluated the sinomenine potential effect on glucocorticoid pharmacodynamics in vitro using a human peripheral blood mononuclear cell (PBMC) culture system. We also disclosed the possible action mechanism of sinomenine with a focus on P-glycoprotein function and glucocorticoid receptor (GR) translocation into nucleus. The median (range) of methylprednisolone IC50 values against the PBMC proliferation was 3.18 (0.45-6.81) ng/mL, whereas the median (range) IC50 values of methylprednisolone combined with 0.03, 0.3, 3, and 30 µM sinomenine were 1.85 (0.05-5.15), 0.83 (0.10-3.90), 0.56(0.09-1.62), and 0.59(0.05-1.30) ng/mL, respectively. Sinomenine significantly decreased the IC50 values of methylprednisolone and enhanced the immunosuppressive effect of methylprednisolone (p < 0.05). Sinomenine alone regulated the GR translocation in both Jurkat T cells and normal human PBMCs, and the combination of sinomenine and methylprednisolone showed stronger GR-modulatory activity than methylprednisolone alone. Thus, the additive effect of sinomenine to promote the methylprednisolone immunosuppressive efficacy was suggested to be related to nuclear GR-translocation. However, sinomenine did not significantly inhibit the P-glycoprotein function in the activated PBMCs, suggesting that sinomenine's additive effect seemed to be unrelated with the P-glycoprotein inhibition.

Arsenic disulfide induced apoptosis and concurrently promoted erythroid differentiation in cytokine-dependent myelodysplastic syndrome-progressed leukemia cell line F-36p with complex karyotype including monosomy 7.

OBJECTIVE: Acute myeloid leukemia progressed from myelodysplastic syndrome (MDS/AML) is generally incurable with poor prognosis for complex karyotype including monosomy 7 (-7). Qinghuang Powder (, QHP), which includes Qing Dai (Indigo naturalis) and Xiong Huang (realgar) in the formula, is effective in treating MDS or MDS/AML even with the unfavorable karyotype, and its therapeutic efficacy could be enhanced by increasing the Xiong huang content in the formula, while Xiong huang contains > 90% arsenic disulfide (As2S2). F-36p cell line was established from a MDS/AML patient with complex karyotype including -7, and was in cytokine-dependent. The present study was to investigate the effects of As2S2 on F-36p cells. METHODS: Cell proliferation was measured by an 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. Cell apoptosis was identified by Annexin V-staining. Cell viability was determined by a propidium iodide (PI) exclusion. Erythroid differentiation was evaluated by the expression of cell surface antigen CD235a (GpA). RESULTS: After treatment with As2S2 at concentrations of 0.5 to 16 µmol/L for 72 h, As2S2 inhibited the proliferation of F-36p cells. The 50% inhibitory concentrations (IC50) of As2S2 against the proliferation of F-36p cells was 6 µmol/L. The apoptotic cells significantly increased in a dose-dependent mannar (P<0.05). The cell viabilities were significantly inhibited by As2S2 dose-dependent in a dose-dependent manner (P<0.05). Significant increases of CD235a-positive cells were concurrently observed (P<0.05) also in a dose-dependent manner. CONCLUSIONS: As2S2 could inhibit proliferation and viability, induce apoptosis, and concurrently promote erythroid differentiation dose-dependently in F-36p cells. As2S2 can inhibit proliferation and viability, induce apoptosis, and concurrently promote erythroid differentiation in cytokine-dependent MDS-progressed human leukemia cell line F-36p with complex karyotype including -7. The data suggest that QHP and/or As2S2 could be a potential candidate in the treatment of MDS or MDS/AML even with unfavorable cytogenetics.

Polymethoxyflavonoids tangeretin and nobiletin increase glucose uptake in murine adipocytes.

Tangeretin and nobiletin are polymethoxyflavonoids that are contained in citrus fruits. Polymethoxyflavonoids are reported to have several biological functions including anti-inflammatory, anti-atherogenic, or anti-diabetic effects. However, whether polymethoxyflavonoids directly affect glucose uptake in tissues is not well understood. In the current study, we investigated whether tangeretin and nobiletin affect glucose uptake in insulin target cells such as adipocytes. We observed that treatment with tangeretin or nobiletin significantly increased the uptake of [(3) H]-deoxyglucose in differentiated 3T3-F442A adipocytes in a concentration-dependent manner. Data showed that phosphatidyl inositol 3 kinase, Akt1/2, and the protein kinase A pathways were involved in the increase in glucose uptake induced by polymethoxyflavonoids. These data suggest that the anti-diabetic action of polymethoxyflavonoids is partly exerted via these signaling pathways in insulin target tissues.