demethoxycurcumin and Glioma

Glioma stem cells (GSCs) play an important role in glioblastoma resistance to conventional therapies and disease recurrence. Here, we assessed the therapeutic effect of a demethoxycurcumin analogue, DMC-BH, on GSCs, and investigated the underlying mechanisms. Our in vitro data demonstrate that DMC-BH inhibits GSC proliferation, and induces apoptosis and autophagy in GSCs. In addition, our results show that DMC-BH effectively crosses the blood-brain barrier to inhibit the growth of intracranial GSC tumors in vivo. DMC-BH significantly increased phosphorylation levels of JNK, ERK and c-Jun in GSCs. Inhibition of JNK and ERK activities reversed the pro-apoptotic effect of DMC-BH in GSCs, indicating that the DMC-BH-induced apoptosis in GSCs is mediated via the JNK/ERK signaling pathway. These results suggest that DMC-BH could potentially serve as a effective therapy against GSCs that acts by targeting the JNK/ERK signaling pathway.

Topics: Animals; Antineoplastic Agents, Phytogenic; Apoptosis; Autophagy; Blood-Brain Barrier; Brain Neoplasms; Cell Cycle Checkpoints; Cell Proliferation; Diarylheptanoids; Glioma; Male; MAP Kinase Signaling System; Mice; Mice, Inbred ICR; Neoplastic Stem Cells; Phosphorylation; Proto-Oncogene Proteins c-jun; Xenograft Model Antitumor Assays

Previous studies showed Demethoxycurcumin (DMC) has stronger anti-glioma and anti-GSCs effects both in vitro and in vivo. In addition, DMC seems to be lower toxicity than TMZ on nude mice. However, this conclusion was confirmed to be wrong in this study. We have evaluated the antitumor efficacy of DMC or TMZ treatment by an orthotopic glioblastoma xenograft model. Nude mice were injected with U87MG-luc cells in the caudate nucleus of the brain and treated with DMC (30 mg/kg q.d.) or TMZ (10 mg/kg q.d.) by intraperitoneal injection. Bioluminescence imaging (BLI) was used to monitoring tumor growth and response to therapy. Western blot was used to detect the expression of p-Akt, cleaved-caspase-3 and Bax. The average value of BLI showed TMZ determined a significant tumor regression while DMC had a mild regression effect on tumor growth compared with control group. Immunohistochemistry for Ki67, proliferating cell nuclear antigen (PCNA), and TUNEL demonstrated that TMZ more effectively inhibited the expression of Ki67 and PCNA, and increased the ratio of TUNEL-positive cells in in situ tumor tissue. Western blot analysis also indicated that TMZ but not DMC more significantly decreased p-Akt and increased cleaved-caspase-3 and Bax expression.These findings suggested a fact that TMZ appear to be more effective in controlling the growth of glioblastoma than DMC in an orthotopic glioblastoma xenograft model.

Topics: Animals; Antineoplastic Agents, Alkylating; Apoptosis; Brain Neoplasms; Cell Proliferation; Curcumin; Diarylheptanoids; Glioma; Humans; Male; Mice; Mice, Nude; Temozolomide; Tumor Cells, Cultured; Xenograft Model Antitumor Assays

Recently, we have reported that Demethoxycurcumin induced Reactive oxygen species via inhibition of Mitochondrial Superoxide Dismutase is an initial event to trigger apoptosis through caspase-8 and 9 activation and to inhibit Akt/NF-κB survival signaling in human glioma U87 MG cells (Kumar et al., 2018). Although cell-cycle disruption had been suggested to be the possible mechanism for DMC inhibitory effect on human glioma U87 MG cells, comprehensive mechanisms of cell-cycle arrest caused by DMC are not fully understood. The present study was designed to elucidate the DMC induced mechanism of cell cycle arrest in human glioma U87 MG cells. In this study, the results illustrated that DMC induced Reactive oxygen species (ROS) leads to reduced expression of CDC25C, Cyclin B1 and CDK1 (Thr161) triggers G2/M cell cycle arrest in U87 MG glioma cells. Moreover, the DMC induced ROS generation activates ubiquitination and proteasome degradation of CDC25C and Cyclin B1 in U87MG glioma cells. In addition, the immunoprecipitation results showed that significant dissociation of CDK1or CDC2-Cyclin B1 complex leads to G2/M cell cycle arrest. To explore the possibility of direct involvement of DMC in the dissociation of CDK1/Cyclin B1 complex, the molecular docking and MD simulation studies were carried. The results showed that DMC nicely fitted into the binding site of CDK1 and Cyclin B1 with minimum binding energy (ΔG) of -9.46 kcal/mol (Ki = 0.11 μM) and - 9.90 kcal/mol (Ki = 0.05 μM) respectively. Therefore, this is the first study demonstrating CDC25C and Cyclin B1 proteins could be used as potential target for anticancer therapy and DMC may be explored as new therapeutic agent in the cure of Glioblastoma (GBM).

Topics: CDC2 Protein Kinase; cdc25 Phosphatases; Cell Cycle Checkpoints; Cell Division; Cell Line, Tumor; Curcumin; Cyclin B1; Diarylheptanoids; G2 Phase; Glioma; Humans; Molecular Docking Simulation; Proteasome Endopeptidase Complex; Reactive Oxygen Species

Docking analysis of curcumin (C1), demethoxycurcumin (C2) and bisdemethoxycurcumin (C3) with Bcl-2 illustrated that among the three curcuminoids, C2 binds more efficiently into its putative active site. C1, C2 and C3 were purified from turmeric rhizomes to demonstrate the molecular mechanism of their anticancer activity on human glioma U87 cells. Human glioma U87 cells treated with curcuminoids resulted in activation of Bcl-2 mediated G2 checkpoint, which was associated with the induction of G2/M arrest and apoptosis. The binding of C1, C2 and C3 with Bcl-2 protein was confirmed with circular dichroism (CD) spectroscopy. Present work revealed that C2 induced Bcl-2 mediated G2/M arrest and apoptosis most effectively.

Topics: Apoptosis; Binding Sites; Brain Neoplasms; Cell Line, Tumor; Cell Survival; Curcumin; Diarylheptanoids; Down-Regulation; G2 Phase; Glioma; Humans; Proto-Oncogene Proteins c-bcl-2