ROS generation and autophagosome accumulation contribute to the DMAMCL-induced inhibition of glioma cell proliferation by regulating the ROS/MAPK signaling pathway and suppressing the Akt/mTOR signaling pathway

Dual perspective on autophagy in glioma: Detangling the dichotomous mechanisms of signaling pathways for therapeutic insights

Autophagy is a normal physiological process that aids the recycling of cellular nutrients, assisting the cells to cope with stressed conditions. However, autophagy's effect on cancer, including glioma, is uncertain and involves complicated molecular mechanisms. Several contradictory reports indicate that autophagy may promote or suppress glioma growth and progression. Autophagy inhibitors potentiate the efficacy of chemotherapy or radiation therapy in glioma. Numerous compounds stimulate autophagy to cause glioma cell death. Autophagy is also involved in the therapeutic resistance of glioma. This review article aims to detangle the complicated molecular mechanism of autophagy to provide a better perception of the two-sided role of autophagy in glioma and its therapeutic implications. The protein and epigenetic modulators of the cytoprotective and cytotoxic role of autophagy are described in this article. Moreover, several signaling pathways are associated with autophagy and its effects on glioma. We have reviewed the molecular pathways and highlighted the signaling axis involved in cytoprotective and cytotoxic autophagy. Additionally, this article discusses the role of autophagy in therapeutic resistance, including glioma stem cell maintenance and tumor microenvironment regulation. It also summarizes several investigations on the anti-glioma effects of autophagy modulators to understand the associated mechanisms and provide insights regarding its therapeutic implications.

Pharmacological potential of micheliolide: A focus on anti-inflammatory and anticancer activities

Micheliolide (MCL) is a chief constituent of plants such as Magnolia grandiflora L., Michelia compressa (Maxim.) Sarg. and Michelia champaca L. It is known to exhibit significant anticancer activity by various scientific investigations. This review aims to emphasize the anticancer and antiinflammatory activities of MCL. In this review, we summarized the published data in peer-reviewed manuscripts published in English. Our search was based on the following scientific search engines and databases: Scopus, Google Scholar, ScienceDirect, Springer, PubMed, and SciFinder, MCL possesses a broad spectrum of medicinal properties like other sesquiterpene lactones. The anticancer activity of this compound may be attributed to the modulation of several signaling cascades (PI3K/Akt and NF-κB pathways). It also induces apoptosis by arresting the cell cycle at the G1/G0 phase, S phase, and G2/M phase in many cancer cell lines. Very little data is available on its modulatory action on other signaling cascades like MAPK, STAT3, Wnt, TGFβ, Notch, EGFR, etc. This compound can be potentiated as a novel anticancer drug after thorough investigations in vitro, in vivo, and in silico-based studies.

Hirudin inhibits glioma growth through mTOR-regulated autophagy

Glioma is the most common primary malignant brain tumour, and survival is poor. Hirudin has anticancer pharmacological effects through suppression of glioma cell progression, but the molecular target and mechanism are poorly understood. In this study, we observed that hirudin dose- and time-dependently inhibited glioma invasion, migration and proliferation. Mechanistically, hirudin activated LC3-II but not Caspase-3 to induce the autophagic death of glioma cells by decreasing the phosphorylation of mTOR and its downstream substrates ULK1, P70S6K and 4EBP1. Furthermore, hirudin inhibited glioma growth and induced changes in autophagy in cell-derived xenograft (CDX) nude mice, with a decrease in mTOR activity and activation of LC3-II. Collectively, our results highlight a new anticancer mechanism of hirudin in which hirudin-induced inhibition of glioma progression through autophagy activation is likely achieved by inhibition of the mTOR signalling pathway, thus providing a molecular basis for hirudin as a potential and effective clinical drug for glioma therapy.

The antitumor effect of the novel agent MCL/ACT001 in pancreatic ductal adenocarcinoma

PURPOSE

Pancreatic ductal adenocarcinoma (PDAC) is a major challenge in cancer therapy, there are more than four hundred thousand deaths per year, and the 5-year survival rate is less than 10%. The incidence continues to rise. Treatment with classic drugs offers limited therapeutic benefits. The aim of this study was to investigate the mechanism and effect of the new agent ACT001, the active metabolite of Micheliolide (MCL), in vitro and in vivo against PDAC.

METHODS

MTT assay, wound healing assay, and flow cytometry were used to assess the effects of MCL/ACT001 in vitro. DCFH-DA assay was used to assess ROS accumulation. Western blotting, immunohistochemical staining and TUNEL assay were also conducted to determine the mechanisms. PANC-1-Luc cells and bioluminescent reporter imaging were used to assess antitumor effect of ACT001 using a orthotopic xenograft model in vivo.

RESULTS

MCL/ACT001 significantly inhibited cell growth in PDAC in a dose-dependent manner, induced cell apoptosis, cell migration and reactive oxygen species (ROS) accumulation in vitro. In vivo, ACT001 (400 mg/kg/day) inhibited PDAC tumor growth in orthotopic xenograft mice. We verified that EGFR and Akt were markedly overexpressed in PDAC cells and patient tumors. Mechanistic investigations revealed that MCL exerted its antitumor activity via regulation of the EGFR-Akt-Bim signaling pathway, thus inducing Bim expression both in vitro and in vivo.

CONCLUSION

MCL/ACT001 is a highly promising agent in the treatment of PDAC patients.

ACT001 inhibits pituitary tumor growth by inducing autophagic cell death via MEK4/MAPK pathway

ACT001, derived from traditional herbal medicine, is a novel compound with effective anticancer activity in clinical trials. However, little is known regarding its role in pituitary adenomas. Here, we demonstrated that ACT001 suppressed cell proliferation and induced cell death of pituitary tumor cells in vitro and in vivo. ACT001 was also effective in suppressing the growth of different subtypes of human pituitary adenomas. The cytotoxic mechanism ACT001 employed was mainly related to autophagic cell death (ACD), indicated by autophagosome formation and LC3-II accumulation. In addition, ACT001-mediated inhibitory effect decreased when either ATG7 was downregulated or cells were cotreated with autophagy inhibitor 3-methyladenine (3-MA). RNA-seq analysis showed that mitogen-activated protein kinase (MAPK) pathway was a putative target of ACT001. Specifically, ACT001 treatment promoted the phosphorylation of JNK and P38 by binding to mitogen-activated protein kinase kinase 4 (MEK4). Our study indicated that ACT001-induced ACD of pituitary tumor cells via activating JNK and P38 phosphorylation by binding with MEK4, and it might be a novel and effective anticancer drug for pituitary adenomas.

Potential targets and treatments affect oxidative stress in gliomas: An overview of molecular mechanisms

Oxidative stress refers to the imbalance between oxidation and antioxidant activity in the body. Oxygen is reduced by electrons as part of normal metabolism leading to the formation of various reactive oxygen species (ROS). ROS are the main cause of oxidative stress and can be assessed through direct detection. Oxidative stress is a double-edged phenomenon in that it has protective mechanisms that help to destroy bacteria and pathogens, however, increased ROS accumulation can lead to host cell apoptosis and damage. Glioma is one of the most common malignant tumors of the central nervous system and is characterized by changes in the redox state. Therapeutic regimens still encounter multiple obstacles and challenges. Glioma occurrence is related to increased free radical levels and decreased antioxidant defense responses. Oxidative stress is particularly important in the pathogenesis of gliomas, indicating that antioxidant therapy may be a means of treating tumors. This review evaluates oxidative stress and its effects on gliomas, describes the potential targets and therapeutic drugs in detail, and clarifies the effects of radiotherapy and chemotherapy on oxidative stress. These data may provide a reference for the development of precise therapeutic regimes of gliomas based on oxidative stress.

Sesquiterpene Lactones and Cancer: New Insight into Antitumor and Anti-inflammatory Effects of Parthenolide-Derived Dimethylaminomicheliolide and Micheliolide

Applied science nowadays works on the isolation and application of biological macromolecules (BMM). These BMM are isolates from plants using different techniques and used as anticancer, antimicrobial, and anti-inflammatory drugs. Parthenolide (PLT) is one of the most important biological macromolecules and a naturally occurring sesquiterpene lactone that is isolated from a plant species Tanacetum parthenium (T. parthenium). The anti-cancer and anti-inflammatory effects of PTL isolated from T. parthenium were previously reported and summarized in detail. These biological activities make it a vital candidate for further researches and drugs development. As per the previously obtained findings, the sesquiterpene is very much known for some biological activities; therefore, the anti-cancer and anti-inflammatory activities of the sesquiterpene were critically reviewed. During the research process, PTL was found to be unstable in both acidic and basic conditions with low solubility, so structurally related compounds micheliolide (MCL) and Dimethylaminomicheliolide (DMAMCL) (a prodrug of MCL) were developed. In this article, we briefly review the therapeutic effects of PTL and its derivative DMAPT on inflammatory diseases and tumors, focusing on the current application of PTL in targeted therapy and combination therapy, together with anti-inflammatory and anti-tumor functions of MCL and DMAMCL. The uniqueness of this biological macromolecule is not to harm the normal cell but target the cancerous cells. Therefore, the current literature review might be helpful and useful for prospects based on the effects of MCL and DMAMCL on cancer.

Transferrin decorated-nanostructured lipid carriers (NLCs) are a promising delivery system for rapamycin in Alzheimer's disease: An in vivo study

Alzheimer's disease (AD), the most common neurodegenerative disorder, is characterized by progressive cognitive impairment and memory loss. The mammalian target of rapamycin (mTOR) signaling pathway could regulate learning and memory. The effect of rapamycin (Rapa) on mTOR activity could slow or prevent the progression of AD by affecting various essential cellular processes. Previously, we prepared transferrin (Tf) decorated-nanostructured lipid carriers (NLCs) for rapamycin (150 ± 9 nm) to protect the drug from chemical and enzymatic degradation and for brain targeted delivery of rapamycin. Herein, the effect of Tf-NLCs compared to untargeted anionic-NLCs and free rapamycin, were studied in amyloid beta (Aβ) induced rat model of AD. Behavioral test revealed that the Rapa Tf-NLCs were able to significantly improve the impaired spatial memory induced by Aβ. Histopathological studies of hippocampus also showed neural survival in Rapa Tf-NLCs treated group. The immunosuppressive, and delayed wound healing adverse effects in the rapamycin solution treated group were abolished by incorporating the drug into NLCs. The Aβ induced oxidative stress was also reduced by Rapa Tf-NLCs. Molecular studies on the level of Aβ, autophagy (LC3) and apoptotic (caspase-3) markers, and mTOR activity revealed that the Rapa Tf-NLCs decreased the Aβ level and suppressed the toxic effects of Aβ plaques by modulating the mTOR activity and autophagy, and decreasing the apoptosis level. As a conclusion, the designed Tf-NLCs could be an appropriate and a safe brain delivery system for rapamycin and make this drug more efficient in AD for improving memory and neuroprotection.

Anti-Cancer Pectins and Their Role in Colorectal Cancer Treatment

A class of plant polysaccharides, pectin is known to display several medicinal properties including in cancer. There is some evidence that pectin from some fruits can reduce the severity of colorectal cancer (CRC) due to its antiproliferative, anti-inflammatory, antimetastatic and pro-apoptotic properties. Pectin fermentation in the colon induces antiproliferative activity via butyrate. Research also showed that pectin acts as a potent inducer of programmed cell death and cell-cycle arrest, thereby selectively targeting cancer cells. Pectin can limit oxidative stress to maintain cellular homeostasis while increasing reactive oxygen species damage to activate cancer cell death. Pectin regulates various signaling cascades, e.g., signal transduction and transcriptional activator and mitogen-activated protein kinase signaling, that contribute to its anticancer activity. By curbing inflammation-activated signaling and bolstering immune-protective mechanisms pectin can eradicate CRC. Due to its chemical structure, pectin can also inhibit galectin-3 and suppress tumor growth and metastasis. Prior reports also suggested that pectin is beneficial to use alongside the CRC standard care. Pectin can increase sensitivity to conventional CRC drugs, alleviate unwanted side effects and reduce drug resistance. Although some preclinical studies are promising, early clinical trials are showing some evidence for pectin's efficacy in tumor growth inhibition and preventing metastasis in some cancers; however, the clinical use of pectin in CRC therapy is not yet well established. Further studies are needed to confirm the efficacy of pectin treatment as a valid clinical therapy for CRC in humans.

Dimethylaminomicheliolide Sensitizes Cancer Cells to Radiotherapy for Synergistic Combination with Immune Checkpoint Blockade

Radiotherapy (RT) has demonstrated synergy with immune checkpoint blockade (ICB) in preclinical models. However, its potential as an immunoadjuvant is limited by low immunogenicity at low radiation doses and immunosuppression at high radiation doses. It is hypothesized that radiosensitizers can enhance both the anticancer and immunogenic effects of low-dose radiation. Herein the authors report the antitumor immunity of combined RT and immunotherapy with dimethylaminomicheliolide (DMAMCL), a prodrug of the anti-inflammatory sesquiterpene lactone micheliolide (MCL). DMAMCL sensitized cancer cells to a single fraction of RT in vitro by inducing apoptosis and DNA double-strand breaks. DMAMCL with 5 fractions of 2 Gy focal X-ray irradiation led to significant anticancer efficacy in subcutaneous and spontaneous models of murine cancer. DMAMCL-sensitized RT upregulated programmed death-ligand 1 (PD-L1) expression in the tumors. Combination of DMAMCL-sensitized RT with anti-PD-L1 ICB significantly enhanced antitumor efficacy by increasing tumor-infiltrating CD4+ and CD8+ T cells and establishing immune memory.

Antitumor effects of the small molecule DMAMCL in neuroblastoma via suppressing aerobic glycolysis and targeting PFKL

Background

Neuroblastoma (NB) is a common solid malignancy in children that is associated with a poor prognosis. Although the novel small molecular compound Dimethylaminomicheliolide (DMAMCL) has been shown to induce cell death in some tumors, little is known about its role in NB.

Methods

We examined the effect of DMAMCL on four NB cell lines (NPG, AS, KCNR, BE2). Cellular confluence, survival, apoptosis, and glycolysis were detected using Incucyte ZOOM, CCK-8 assays, Annexin V-PE/7-AAD flow cytometry, and Seahorse XFe96, respectively. Synergistic effects between agents were evaluated using CompuSyn and the effect of DMAMCL in vivo was evaluated using a xenograft mouse model. Phosphofructokinase-1, liver type (PFKL) expression was up- and down-regulated using overexpression plasmids or siRNA.

Results

When administered as a single agent, DMAMCL decreased cell proliferation in a time- and dose-dependent manner, increased the percentage of cells in SubG1 phase, and induced apoptosis in vitro, as well as inhibiting tumor growth and prolonging survival in tumor-bearing mice (NGP, BE2) in vivo. In addition, DMAMCL exerted synergistic effects when combined with etoposide or cisplatin in vitro and displayed increased antitumor effects when combined with etoposide in vivo compared to either agent alone. Mechanistically, DMAMCL suppressed aerobic glycolysis by decreasing glucose consumption, lactate excretion, and ATP production, as well as reducing the expression of PFKL, a key glycolysis enzyme, in vitro and in vivo. Furthermore, PFKL overexpression attenuated DMAMCL-induced cell death, whereas PFKL silencing promoted NB cell death.

Conclusions

The results of this study suggest that DMAMCL exerts antitumor effects on NB both in vitro and in vivo by suppressing aerobic glycolysis and that PFKL could be a potential target of DMAMCL in NB.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02330-y.

The petroleum ether extract of Brassica rapa L. induces apoptosis of lung adenocarcinoma cells via the mitochondria-dependent pathway

Brassica rapa L. is one of the most popular traditional foods with a variety of biological activities. In this study, the petroleum ether extract of B. rapa was separated by silica gel column chromatography, and named BRPS, which was identified by LC-MS. The effects and pharmacological mechanisms of BRPS on the treatment of lung cancer were investigated both in vitro and in vivo. The results showed that BRPS significantly inhibited the proliferation of both human lung cancer A549 and mouse lung cancer LLC cells, while its toxicity to normal cells was lower than that of cancer cells. BRPS induced cell cycle arrest at the G2/M phase and significantly reduced the levels of CDK1 and CyclinB1 in A549 cells. Moreover, BRPS induced apoptosis in a dose-dependent manner, and increased the Bax/Bcl-2 ratio, while it decreased mitochondrial membrane potential, promoted the release of cytochrome c, activated caspase 9 and 3, and enhanced the degradation of PARP in A549 cells. Furthermore, the levels of reactive oxygen species (ROS) were also upregulated by BRPS and ROS inhibitor reversed BRPS-induced apoptosis. Importantly, BRPS significantly suppressed the growth of LLC cells in vivo without any obvious side effect on body weight and organs of mice, and increased the proportion of B cells, CD4⁺ T cells, CD8⁺ T cells and CD44⁺CD8⁺ T cells in the spleen. These results revealed that BRPS inhibited the growth of lung cancer cells through inducing cell cycle arrest, mitochondria-dependent apoptosis, and activating immunity of mice, and BRPS might be a potential anti-tumor functional food and promising agent for the treatment of lung cancer.

Traditional Chinese medicine (TCM) as a source of new anticancer drugs

Covering: up to July 2020Drugs derived from traditional Chinese medicine (TCM) include both single chemical entities and multi-component preparations. Drugs of both types play a significant role in the healthcare system in China, but are not well-known outside China. The research and development process, the molecular mechanisms of action, and the clinical evaluation associated with some exemplificative anticancer drugs based on TCM are discussed, along with their potential of integration in western medicine.

Itraconazole exerts anti-liver cancer potential through the Wnt, PI3K/AKT/mTOR, and ROS pathways

Hepatocellular carcinoma (HCC) is one of the most common cancers with the highest morbidity and mortality. It is necessary to develop new anti-liver cancer drugs. Itraconazole is a popular systemic anti-fungal drug with a strong anti-tumor effect. However, so far, it is not clear whether itraconazole has specific anti-tumor effect on liver cancer. The purpose of this study was to investigate itraconazole resistant effect of liver cancer and to explore its potential anti-cancer mechanism. The effect of itraconazole on the proliferation of liver cancer cells was studied with MTT assay. Flow cytometry was used to determine the effect of itraconazole on apoptosis, cell cycle distribution, changes in intracellular reactive oxygen species (ROS) and mitochondrial membrane potential (MMP). In addition, after DAPI staining, nuclear morphological changes were observed under the fluorescent microscope, and the release of lactate dehydrogenase (LDH) was measured using the microplate reader. Finally, the expressions of proteins related to the anti-tumor signaling pathway were determined by Western blotting. The results showed that itraconazole significantly inhibited the proliferation of HepG2 and Bel-7405 cells. In addition, the data showed that itraconazole induced apoptosis in HepG2 cells, increased the production of ROS, blocked cell cycle, and decreased MMP. Furthermore, itraconazole inhibited HCC cell growth and promoted apoptosis through the Hh, Wnt/catenin, AKT/mTOR/S6K, ROS and death receptor pathways. Finally, we come to the conclusion that itraconazole exerts anti-liver cancer effect, and has potential for use as a new drug for liver cancer in clinic.

Micheliolide suppresses the viability, migration and invasion of U251MG cells via the NF-κB signaling pathway

Micheliolide (MCL), a sesquiterpene lactone isolated from Michelia compressa and Michelia champaca, has been used previously to inhibit the NF-κB signaling pathway. MCL has exerted various therapeutic effects in numerous types of disease, such as inflammatory and cancer. However, to the best of our knowledge, its underlying anticancer mechanism remains to be understood. The present study aimed to investigate the effects of MCL on human glioma U251MG cells and to determine the potential anticancer mechanism of action of MCL. From Cell Counting Kit-8, colony formation assay, apoptosis assay and Confocal immunofluorescence imaging analysis, the results revealed that MCL significantly inhibited cell viability in vitro and induced cell apoptosis via activation of the cytochrome c/caspase-dependent apoptotic pathway. In addition, MCL also suppressed cell invasion and metastasis via the wound healing and Transwell invasion assays. Furthermore, western blot and reverse transcription PCR analyses demonstrated that MCL significantly downregulated cyclooxygenase-2 (COX-2) expression levels, which may have partially occurred through the inactivation of the NF-κB signaling pathway. In conclusion, the results of the present study indicated that MCL may inhibit glioma carcinoma growth by downregulating the NF-κB/COX-2 signaling pathway, which suggested that MCL may be a novel and alternative antitumor agent for the treatment of human glioma carcinoma.

IMMUNEPOTENT CRP induces DAMPS release and ROS-dependent autophagosome formation in HeLa and MCF-7 cells

Background

IMMUNEPOTENT CRP (ICRP) can be cytotoxic to cancer cell lines. However, its widespread use in cancer patients has been limited by the absence of conclusive data on the molecular mechanism of its action. Here, we evaluated the mechanism of cell death induced by ICRP in HeLa and MCF-7 cells.

Methods

Cell death, cell cycle, mitochondrial membrane potential and ROS production were evaluated in HeLa and MCF-7 cell lines after ICRP treatment. Caspase-dependence and ROS-dependence were evaluated using QVD.oph and NAC pre-treatment in cell death analysis. DAMPs release, ER stress (eIF2-α phosphorylation) and autophagosome formation were analyzed as well. Additionally, the role of autophagosomes in cell death induced by ICRP was evaluated using SP-1 pre-treatment in cell death in HeLa and MCF-7 cells.

Results

ICRP induces cell death, reaching CC₅₀ at 1.25 U/mL and 1.5 U/mL in HeLa and MCF-7 cells, respectively. Loss of mitochondrial membrane potential, ROS production and cell cycle arrest were observed after ICRP CC₅₀ treatment in both cell lines, inducing the same mechanism, a type of cell death independent of caspases, relying on ROS production. Additionally, ICRP-induced cell death involves features of immunogenic cell death such as P-eIF2α and CRT exposure, as well as, ATP and HMGB1 release. Furthermore, ICRP induces ROS-dependent autophagosome formation that acts as a pro-survival mechanism.

Conclusions

ICRP induces a non-apoptotic cell death that requires an oxidative stress to take place, involving mitochondrial damage, ROS-dependent autophagosome formation, ER stress and DAMPs’ release. These data indicate that ICRP could work together with classic apoptotic inductors to attack cancer cells from different mechanisms, and that ICRP-induced cell death might activate an immune response against cancer cells.

Naringin Induces Lysosomal Permeabilization and Autophagy Cell Death in AGS Gastric Cancer Cells

Autophagy is a process of active programmed cell death, where a dying cell induces autophagosomes and subsequently regulated by degradative machinery. The aim of this study was to investigate the mechanism behind induction of autophagic cell death by Naringin flavonoid in AGS cancer cells. Growth inhibition of AGS cells showed downregulation of PI3K/Akt/mTOR signaling by Naringin treatment. Transmission electron microscopy observation showed swollen mitochondria and lysosome near peri-nuclear zone fused with autophagic vacuoles. Rapamycin pre-treatment with Naringin showed significant decrease in mTOR phosphorylation and increase in LC3B activation in AGS cells. Decrease in mTOR phosphorylation is associated with lysosomal function activation was observed by time-dependent treatment of Naringin. Induction of lysosomal membrane permeabilization (LMP) was observed by LAMP1 activation leading lysosomal cell death by releasing Cathepsin D from lysosomal lumen to cytosol. Naringin treated AGS cells showed up-regulating BH3 domain Bad, down-regulating Bcl-xL, and Bad phosphorylation and significant mitochondrial fluorescence intensity expression. Significant localization of mitochondria and LC3B activation was examined by person coefficient correlation. Activation of ERK1/2-p38 MAPKs and production of intracellular ROS has been observed over Naringin treatment. It has also been elucidated that pre-treatment with NAC inhibited mitochondria-LC3B colocalization, where ROS acted as upstream of ERK1/2-p38 MAPKs activation. Lysosomal cell death involvement has been evaluated by BAF A1 pre-treatment, inhibiting LAMP1, Cathepsin D, ROS, and blocking autophagolysosome in AGS cell death. Taken together, these findings show that, Naringin induced autophagy cell death involves LMP mediated lysosomal damage and BH3 protein Bad activation in AGS cancer cells.

DMAMCL exerts antitumor effects on hepatocellular carcinoma both in vitro and in vivo

Hepatocellular carcinoma (HCC) is a common malignancy with a poor prognosis. Dimethylaminomicheliolide (DMAMCL) is a novel antitumor agent that has been tested in phase I clinical trials; however, little is known regarding its effects in HCC. In this study, we found that DMAMCL reduces the viability of HCC cells in a dose- and time-dependent manner. In addition, DMAMCL causes cell cycle arrest at the G2/M phase and inhibits cell invasion and epithelial-mesenchymal transition (EMT). DMAMCL treatment also induces apoptosis via the intrinsic apoptotic pathway in HCC cells, which could be blocked by the pan-caspase inhibitor zVAD-fmk and silencing of Bax/Bak or overexpression of Bcl-2. Furthermore, DMAMCL treatment inactivates the PI3K/Akt pathway and leads to the generation of reactive oxygen species (ROS), which regulate apoptosis and inhibition of PI3K/Akt induced by DMAMCL. In vivo, DMAMCL inhibits tumor growth in mice bearing xenograft HCC tumors without noticeable toxicity. In summary, DMAMCL exerts antitumor effects both in vitro and in vivo and therefore may be applied as a potential therapeutic agent for HCC.

Dimethylaminomicheliolide (DMAMCL) Suppresses the Proliferation of Glioblastoma Cells via Targeting Pyruvate Kinase 2 (PKM2) and Rewiring Aerobic Glycolysis

Glioblastoma (GBM) is the most prevalent malignant tumor in the central nervous system. Aerobic glycolysis, featured with elevated glucose consumption and lactate production, confers selective advantages on GBM by utilizing nutrients to support rapid cell proliferation and tumor growth. Pyruvate kinase 2 (PKM2), the last rate-limiting enzyme of glycolysis, is known to regulate aerobic glycolysis, and considered as a novel cancer therapeutic target. Herein, we aim to describe the cellular functions and mechanisms of a small molecular compound dimethylaminomicheliolide (DMAMCL), which has been used in clinical trials for recurrent GBM in Australia. Our results demonstrate that DMAMCL is effective on the inhibition of GBM cell proliferation and colony formation. MCL, the active metabolic form of DMAMCL, selectively binding to monomeric PKM2 and promoting its tetramerization, was also found to improve the pyruvate kinase activity of PKM2 in GBM cells. In addition, non-targeting metabolomics analysis reveals multiple metabolites involved in glycolysis, including lactate and glucose-6-phosphate, are decreased with DMAMCL treatment. The inhibitory effects of DMAMCL are observed to decrease in GBM cells upon PKM2 depletion, further confirming the importance of PKM2 in DMAMCL sensitivity. In conclusion, the activation of PKM2 by DMAMCL results in the rewiring aerobic glycolysis, which consequently suppresses the proliferation of GBM cells. Hence, DMAMCL represents a potential PKM2-targeted therapeutic agent against GBM.

Cytotoxic effect of crude and purified pectins from Campomanesia xanthocarpa Berg on human glioblastoma cells

A new source of pectin with a cytotoxic effect on glioblastoma cells is presented. A homogeneous GWP-FP-S fraction (M_w of 29,170 g mol^-1) was obtained by fractionating the crude pectin extract (GW) from Campomanesia xanthocarpa pulp. According to the monosaccharide composition, the GWP-FP-S was composed of galacturonic acid (58.8%), arabinose (28.5%), galactose (11.3%) and rhamnose (1.1%), comprising 57.7% of homogalacturonans (HG) and 42.0% of type I rhamnogalacturonans (RG-I). These structures were characterized by chromatographic and spectroscopic methods; GW and GWP-FP-S fractions were evaluated by MTT and crystal violet assays for their cytotoxic effects. Both fractions induced cytotoxicity (15.55-37.65%) with concomitant increase in the cellular ROS levels in human glioblastoma cells at 25-400 μg mL^-1, after 48 h of treatment, whereas no cytotoxicity was observed for normal NIH 3T3 cells. This is the first report of in vitro bioactivity and the first investigation of the antitumor potential of gabiroba pectins.