demethoxycurcumin and Glioblastoma

Glioblastoma multiforme (GBM) is a poorly curable disease due to its profound chemoresistance. Despite recent advances in surgery, radiotherapy and chemotherapy, the efficient treatment of GBMs is still a clinical challenge. Beside others, AT101, the R-(-) enantiomer of gossypol, and demethoxycurcumin (DMC), a curcumin-related demethoxy compound derived from Curcuma longa, were considered as possible alternative drugs for GBM therapy.. Using different human primary GBM cell cultures in a long-term stimulation in vitro model, the cytotoxic and anti-proliferative effects of single and combined treatment with 5 µM AT101 and 5 µM or 10 µM DMC were investigated. Furthermore, western blots on pAkt and pp44/42 as well as JC-1 staining and real-time RT-PCR were performed to understand the influence of the treatment at the molecular and gene level.. Due to enhanced anti-proliferative effects, we showed that combined therapy with both drugs was superior to a single treatment with AT101 or DMC. Here, by determination of the combination index, a synergism of the combined drugs was detectable. Phosphorylation and thereby activation of the kinases p44/42 and Akt, which are involved in proliferation and survival processes, were inhibited, the mitochondrial membrane potential of the GBM cells was altered, and genes involved in dormancy-associated processes were regulated by the combined treatment strategy.. Combined treatment with different drugs might be an option to efficiently overcome chemoresistance of GBM cells in a long-term treatment strategy.

Topics: Antineoplastic Agents, Phytogenic; Antineoplastic Combined Chemotherapy Protocols; Brain Neoplasms; Cell Proliferation; Diarylheptanoids; Dose-Response Relationship, Drug; Drug Synergism; Gene Expression; Glioblastoma; Gossypol; Humans; Membrane Potential, Mitochondrial; Signal Transduction; Tumor Cells, Cultured

We analyzed the role of ABCG2, a drug transporter, in determining the sensitivity of glioma stem cells (GSCs) to demethoxycurcumin (DMC). We first demonstrated that ABCG2 is more highly expressed in GSCs than primary astrocytes. Modulation of ABCG2 levels in GSCs by transfection of ABCG2 shRNA or a lentiviral vector encoding ABCG2 revealed an inverse relation between ABCG2 levels and DMC-induced GSC growth inhibition. Suppressing ABCG2 increased DMC-induced apoptosis and G0/G1 cell cycle arrest in GSCs. It also increased levels reactive oxygen species (ROS) in GSCs treated with DMC, resulting in increased cytochrome C and caspase-3 activity. When GSCs transfected with ABCG2 shRNA or overexpressing ABCG2 were xenografted and the tumor-bearing, immunodeficient mice were treated with DMC, ABCG2 expression suppressed the tumor proliferation rate (T/C %). These findings demonstrate that ABCG2 expression is critical for DMC resistance in GSCs and is a potential therapeutic target for GBM.

Topics: Animals; Antineoplastic Agents; ATP Binding Cassette Transporter, Subfamily G, Member 2; Cell Line, Tumor; Cell Proliferation; Curcumin; Diarylheptanoids; Down-Regulation; Drug Resistance, Neoplasm; Glioblastoma; Humans; Mice; Mice, Inbred BALB C; Mice, Nude; Neoplasm Proteins; Neoplastic Stem Cells; Random Allocation; Reactive Oxygen Species; Transfection; Xenograft Model Antitumor Assays

Temozolomide (TMZ) is widely used for treating glioblastoma (GBM), which can effectively inhibit the GBM growth for some months; however, it still could not prevent the invariable recurrence of GBM. The existence of glioma stem cells (GSCs) was considered to be a key factor. But TMZ has poor effects on GSCs. Recently, demethoxycurcumin (DMC) has been shown to display anti-tumor activities in malignant gliomas. However, its effects and the potential mechanisms on GSCs were still unclear. Our study showed that DMC was prior to TMZ on resulting in a significant increase in GSC apoptosis and a marked inhibition of cell growth in vitro. And combined treatment of DMC and TMZ showed more significant anti-GSC effects. Further research into the underlying mechanism demonstrated that this novel combinatorial regimen leads to changes of multiple cell signaling pathways including reactive oxygen species (ROS) production and caspase-3 signaling mitochondria-related apoptosis activation as well as inactivation of JAK/STAT3 signaling pathway. Taken together, our data demonstrate that the anti-GSC effects of DMC are better than TMZ, and combined treatment of DMC and TMZ has much stronger effects on GSCs.

Topics: Apoptosis; Caspase 3; Cell Proliferation; Curcumin; Dacarbazine; Diarylheptanoids; Glioblastoma; Humans; Neoplastic Stem Cells; Primary Cell Culture; Reactive Oxygen Species; Signal Transduction; Temozolomide

Temozolomide (TMZ) is widely used for treating glioblastoma (GBM), which can effectively inhibit the GBM growth for some months; however, it still cannot prevent the invariable recurrence of GBM. Improving the chemotherapeutic sensitization becomes an urgent agenda. In this study, we found low-dose demethoxycurcumin (DMC) could enhance the sensitivity of TMZ on glioma cells, and high-dose DMC has more significant effects on GBM cells compared with TMZ treatment alone both in vitro and in vivo. And co-administration of DMC and TMZ resulted in a significant increase in GBM apoptosis and a marked inhibition of cell growth pathogenesis of GBM. Mechanistically, DMC and TMZ synergistically increase intracellular level of reactive oxygen species (ROS) production, activate caspase-3-dependent apoptotic pathway, and inactivate of JAK/STAT3 signaling pathway in GBMs, which account for the cell apoptosis and proliferation inhibition. Together, these data implicate that low-dose DMC combined with TMZ represents an effective therapy regimen against GBMs by targeting multiple signaling pathways.

Topics: Animals; Antineoplastic Agents, Phytogenic; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Cell Division; Cell Line, Tumor; Curcumin; Dacarbazine; Diarylheptanoids; Drug Synergism; G1 Phase; Glioblastoma; Humans; Janus Kinases; Mice; Mice, Nude; Neoplasm Proteins; Reactive Oxygen Species; Signal Transduction; STAT3 Transcription Factor; Temozolomide; Tumor Stem Cell Assay; Xenograft Model Antitumor Assays