Chao-Ming Hung

Hispidulin potently inhibits human glioblastoma multiforme cells through activation of AMP-activated protein kinase (AMPK).

Glioblastoma multiforme (GBM) is the most common and lethal type of primary brain tumor. Despite recent therapeutic advances in other cancers, the treatment of GBM remains ineffective and essentially palliative. The current focus lies in the finding of components that activate the AMP-activated protein kinase (AMPK), one key enzyme thought to be activated during the caloric restriction (CR). In the present study, we found that treatment of hispidulin, a flavone isolated from Saussurea involucrate Kar. et Kir., resulted in dose-dependent inhibition of GBM cellular proliferation. Interestingly, we show that hispidulin activated AMPK in GBM cells. The activation of AMPK suppressed downstream substrates, such as the mammalian target of rapamycin (mTOR) and eukaryotic initiation factor 4E-binding protein-1 (4E-BP1), and resulted in a general decrease in mRNA translation. Moreover, hispidulin-activated AMPK decreases the activity and/or expression of lipogenic enzymes, such as fatty acid synthase (FASN) and acetyl-CoA carboxylase (ACC). Furthermore, hispidulin blocked the progression of the cell cycle at the G1 phase and induced apoptosis by inducing p53 expression and further upregulating p21 expression in GBM cells. On the basis of these results, we demonstrated that hispidulin has the potential to be a chemopreventive and therapeutic agent against human GBM.

Hispidulin sensitizes human ovarian cancer cells to TRAIL-induced apoptosis by AMPK activation leading to Mcl-1 block in translation.

Whether hispidulin, a flavone from traditional Chinese medicine, can modulate the anticancer effects of the tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL), the cytokine currently in clinical trials was investigated. In the present study, we found that hispidulin potentiated the TRAIL-induced apoptosis in human ovarian cancer cells and converted TRAIL-resistant cells to TRAIL-sensitive cells. When examined for its mechanism, we found that hispidulin was highly effective in activation of caspases 8 and caspase 3 and consequent poly(ADP-ribose) polymerase (PARP) cleavage. Moreover, we found that hispidulin downregulated the expression of Mcl-1, Bcl-2, and Bcl-xL. Whereas the downregulation of Bcl-2 and Bcl-xL was less pronounced, the downregulation of Mcl-1 was quite dramatic and was time-dependent. This sensitization is controlled through the adenosine monophosphate (AMP)-activated protein kinase (AMPK), which is the central energy-sensing system of the cell. Interestingly, we determined that AMPK is activated upon hispidulin treatment, resulting in mammalian target of rapamycin (mTOR) inhibition leading to Mcl-1 decrease. Therefore, our results show a novel mechanism for the sensitization to TRAIL-induced apoptosis linking hispidulin treatment to Mcl-1 downexpression. In addition, this study provides a rationale for the combined use of death receptor (DR) ligands with AMPK activators or mTOR inhibitors in the treatment of human cancers.

Osthole Suppresses Hepatocyte Growth Factor (HGF)-Induced Epithelial-Mesenchymal Transition via Repression of the c-Met/Akt/mTOR Pathway in Human Breast Cancer Cells

Substantial activation of the HGF/c-Met signaling pathway is involved in the progression of several types of cancers and associated with increased tumor invasion and metastatic potential. Underlying HGF-induced tumorigenesis, epithelial to mesenchymal transition (EMT) shows a positive correlation with progression in patients. We previously determined that osthole is a potent fatty acid synthase (FASN) inhibitor. FASN is implicated in cancer progression and may regulate lipid raft function. We therefore examined whether osthole could block HGF-induced tumorigenesis by disrupting lipid rafts. Here, we found that osthole could abrogate HGF-induced cell scattering, migration, and invasion in MCF-7 breast cancer cells. Osthole also effectively inhibited the HGF-induced decrease of E-cadherin and increase of vimentin via down-regulation of phosphorylated Akt and mTOR. Interestingly, osthole blocked HGF-induced c-Met phosphorylation and repressed the expression of total c-Met protein in MCF-7 cells. In addition, C75, a pharmacological inhibitor of FASN, repressed the expression of total c-Met protein in MCF-7 cells. Consistent with a role for FASN, loss of c-Met in cells treated with osthole was prevented by the exogenous addition of palmitate. Briefly, our result suggests a connection between FASN activity and c-Met protein expression and that osthole is a potential compound for breast cancer therapy by targeting the major pathway of HGF/c-Met-induced EMT.

Aloe-emodin inhibits HER-2 expression through the downregulation of Y-box binding protein-1 in HER-2-overexpressing human breast cancer cells

Human epidermal growth factor receptor-2 (HER-2)-positive breast cancer tends to be aggressive, highly metastatic, and drug resistant and spreads rapidly. Studies have indicated that emodin inhibits HER-2 expression. This study compared the HER-2-inhibitory effects of two compounds extracted from rhubarb roots: aloe-emodin (AE) and rhein. Our results indicated that AE exerted the most potent inhibitory effect on HER-2 expression. Treatment of HER-2-overexpressing breast cancer cells with AE reduced tumor initiation, cell migration, and cell invasion. AE was able to suppress YB-1 expression, further suppressing downstream HER-2 expression. AE suppressed YB-1 expression through the inhibition of Twist in HER-2-overexpressing breast cancer cells. Our data also found that AE inhibited cancer metastasis and cancer stem cells through the inhibition of EMT. Interestingly, AE suppressed YB-1 expression through the downregulation of the intracellular integrin-linked kinase (ILK)/protein kinase B (Akt)/mTOR signaling pathway in HER-2-overexpressing breast cancer cells. In vivo study showed the positive result of antitumor activity of AE in nude mice injected with human HER-2-overexpressing breast cancer cells. These findings suggest the possible application of AE in the treatment of HER-2-positive breast cancer.

Inhibition of the insulin-like growth factor 1 receptor by CHM-1 blocks proliferation of glioblastoma multiforme cells

The insulin-like growth factor-1 receptor (IGF-1R) plays a pivotal role in transformation, growth, and survival of glioblastoma multiforme (GBM) cells, and has emerged as a general and promising target for cancer treatment. In this study, we examined the anti-tumor effects of CHM-1, a synthetic 6,7-methylenedioxy substituted 2-phenyl-4-quinolone derivative, on GBM cells in vitro and in vivo. CHM-1 selectively blocked IGF-1R auto-phosphorylation, with an ability to distinguish between IGF-1R and related tyrosine kinase receptors, such as insulin receptor (IR), epidermal growth factor receptor (EGFR), platelet-derived growth factor receptor (PDGFR), and fibroblast growth factor receptor (FGFR). Further investigation revealed that, the phosphorylation of ERK1/2 as well as Akt was inhibited in CHM-1 treated GBM8401 cells possibly through the selective blockage of IGF-1R auto-phosphorylation. Our study also showed that p.o. treatment with the hydrophilic dihydrogen phosphate CHM-1P reduced the tumor volumes of the GBM8401 derived tumors in mouse brain and also prolonged the survival rate. The results provided potential opportunities for effective chemotherapy for GBM.

Pculin02H, a curcumin derivative, inhibits proliferation and clinical drug resistance of HER2-overexpressing cancer cells.

Amplification of the HER2 gene (also known as neu or ErbB2) or overexpression of HER2 protein has become a solicitous therapeutic target in metastatic and clinical drug-resistance cancer. In our present work, a new series of curcumin derivatives were designed and synthesized using curcumin as model. Here, we evaluated whether curcumin derivatives have better efficiency to degrade HER2 than curcumin. Among these test compounds, pculin02H had better efficiency to inhibit the expression of HER2 than curcumin. Moreover, pculin02H preferentially suppressed the growth of HER2-overexpressing cancer cell lines. Pculin02H induced G2/M cell cycle arrest followed by apoptosis. Interestingly, our results suggested that a posttranslational mechanism contributed to pculin02H-induced HER2 depletion in HER2-overexpressing cancer cells. We found that pculin02H significantly enhanced the antitumor efficacy of clinical drugs on HER2-overexpressing cancer cells as well as efficiently reduced HER2-induced drug resistance. These findings may provide an alternative preventive or therapeutic strategy against HER2-overexpressing cancer cells.

Body weight management effect of burdock (Arctium lappa L.) root is associated with the activation of AMP-activated protein kinase in human HepG2 cells

Burdock (Arcticum lappa L.) root is used in folk medicine and also as a vegetable in Asian countries. In the present study, burdock root treatment significantly reduced body weight in rats. To evaluate the bioactive compounds, we successively extracted the burdock root with ethanol (AL-1), and fractionated it with n-hexane (AL-2), ethyl acetate (AL-3), n-butanol (AL-4), and water (AL-5). Among these fractions, AL-2 contained components with the most effective hypolipidemic potential in human hepatoma HepG2 cells. AL-2 decreased the expression of fatty acid synthase (FASN) and inhibited the activity of acetyl-coenzyme A carboxylase (ACC) by stimulating AMP-activated protein kinase (AMPK) through the LKB1 pathway. Three active compounds were identified from the AL-2, namely α-linolenic acid, methyl α-linolenate, and methyl oleate. These results suggest that burdock root is expected to be useful for body weight management.

Banana Flower Extract Suppresses Benign Prostatic Hyperplasia by Regulating the Inflammatory Response and Inducing G1 Cell-cycle Arrest

Background/Aim: The banana flower is used for ameliorating urinary disturbance. However, there is limited evidence to support the efficacy or mechanism of action of banana flower against benign prostatic hyperplasia (BPH). In the present study, the anti-BPH activity and mechanisms of banana flower extracts were investigated in vitro and in vivo. Materials and Methods: The banana flower extract is a water-soluble extract obtained by sonication. MTT assay was used to examine whether banana flower extract exhibited cytotoxic effects on BPH-1 cells. The effect of banana flower extract on cell-cycle distribution was examined by flow cytometry. The expression of cell-cycle-regulatory molecules was determined by western blot analysis. Testosterone propionate (TP)-induced rat model of BPH was used to evaluate the anti-BPH activity of banana flower extract in vivo. Results: Banana flower extract reduced epithelial cell line BPH-1 cell viability through cell-cycle arrest at G1 phase. Moreover, banana flower extract reduced the expression of cyclin D1 and cyclin-dependent kinase 6, while it increased the expression of p53 and p27. Interestingly, banana flower extract suppressed BPH-related inflammatory responses through suppressing cyclo-oxygenase-2 expression and prostaglandin E2 production. Finally, banana flower extract administered orally to male rats reduced prostatic weight and serum dihydrotestosterone level, and improved prostate gland morphology. High-performance liquid chromatography revealed that banana flower extract contains citric acid, taurine, pantothenic acid and nicotinic acid components. In summary, banana flower extract may be used as a therapeutic agent for BPH via anti-proliferative and anti-inflammatory activities.

CSC-3436 inhibits TWIST-induced epithelial-mesenchymal transition via the suppression of Twist/Bmi1/Akt pathway in head and neck squamous cell carcinoma: LAI et al.

Head and neck squamous cell carcinoma (HNSCC) is one of the leading causes of cancer deaths worldwide, especially in male. With poor prognosis, significant portions of patients with HNSCC die due to cancer recurrence and tumor metastasis after chemotherapy and targeted therapies. The HNSCC FaDu cell ectopic expression of Twist, a key transcriptional factor of epithelial–mesenchymal transition (EMT), which triggers EMT and results in the acquisition of a mesenchymal phenotype, was used as the cell model. Our results demonstrated that treatment with newly synthesized 2‐(3‐hydroxyphenyl)‐5‐methylnaphthyridin‐4‐one (CSC‐3436), a flavonoid derivative, elicited changes in its cell morphology, upregulated E‐cadherin messenger RNA and protein expression, downregulated N‐cadherin, vimentin, and CD133 (a marker associated with tumor‐initiating cells) in FaDu‐pCDH‐Twist cells. Moreover, CSC‐3436 exposure reduced B cell‐specific Moloney murine leukemia virus integration site 1 (Bmi1) expression regulated by Twist and further suppressed the direct co‐regulation of E‐cadherin by Twist and Bmi1. Interestingly, CSC‐3436 reduced EMT, cancer stemness, and migration/invasion abilities through the inhibition of the Twist/Bmi1‐Akt/β‐catenin pathway. Most importantly, our findings provided new evidence that CSC‐3436 played a crucial role in therapeutic targeting to Bmi1 and its molecular pathway in HNSCC, and it will be valuable in prognostic prediction and treatment.

CHM-1, a novel microtubule-destabilizing agent exhibits antitumor activity via inducing the expression of SIRT2 in human breast cancer cells

Breast cancer is a major public health problem throughout the world. In this report, we investigated whether CHM-1, a novel synthetic antimitotic agent could be developed into a potent antitumor agent for treating human breast cancer. CHM-1 induced growth inhibition in MDA-MB-231, MDA-MB-453 and MCF-7u202fcells in a concentration-dependent manner. Importantly, CHM-1 is less toxic to normal breast (HBL-100) cells. CHM-1 interacted with tubulin, markedly inhibited tubulin polymerization, and disrupted microtubule organization. Proteins from control and CHM-1-treated animal tumor specimens were analyzed by two-dimensional electrophoresis and MALDI-TOF mass spectrometry. Our results indicated that CHM-1 increased the expression of SIRT2 protein, an NAD-dependent tubulin deacetylase. A prodrug strategy was also investigated to address the problem of low aqueous solubility and low bioavailability of the antitumor agent CHM-1. The water-soluble prodrug of CHM-1 (CHM-1-P) was synthesized. After oral and intravenous administration, CHM-1-P induced a dose-dependent inhibition of tumor growth. The aforementioned excellent anti-tumor activity profiles of CHM-1 and its prodrug CHM-1-P, suggests that CHM-1-P deserves to further develop as a clinical trial candidate for treating human breast carcinoma.