Chien Chih Yu

Benzyl isothiocyanate (BITC) induces G 2/M phase arrest and apoptosis in human melanoma A375.S2 cells through reactive oxygen species (ROS) and both mitochondria-dependent and death receptor-mediated multiple signaling pathways

Benzyl isothiocyanates (BITC), a member of the isothiocyanate (ITC) family, inhibits cell growth and induces apoptosis in many types of human cancer cell lines. The present study investigated mechanisms underlying BITC-induced apoptosis in A375.S2 human melanoma cancer cells. To observe cell morphological changes and viability, flow cytometric assays, cell counting, and a contrast-phase microscopic examination were carried out in A375.S2 cells after BITC treatment. Cell cycle distribution and apoptosis were assessed with the analysis of cell cycle by flow cytometric assays, DAPI staining, propidium iodide (PI), and annexin V staining. Apoptosis-associated factors such as reactive oxygen species (ROS) formation, loss of mitochondrial membrane potential (ΔΨ(m)), intracellular Ca(2+) release, and caspase-3 activity were evaluated by flow cytometric assays. Abundance of cell cycle and apoptosis associated proteins was determined by Western blotting. AIF and Endo G expression was examined by confocal laser microscope. Results indicated that (1) BITC significantly reduced cell number and induced cell morphological changes in a dose-dependent manner in A375.S2 cells; (2) BITC induced arrest in cell cycle progression at G(2)/M phase through cyclin A, CDK1, CDC25C/Wee1-mediated pathways; (3) BITC induced apoptosis and increased sub-G(1) population; and (4) BITC promoted the production of ROS and Ca(2+) and loss of ΔΨ(m) and caspase-3 activity. Furthermore, BITC induced the down-regulation of Bcl-2 expression and induced up-regulation of Bax in A375.S2 cells. Moreover, BITC-induced cell death was decreased after pretreatment with N-acetyl-l-cysteine (NAC, a ROS scavenger) in A375.S2 cells. In conclusion, the results showed that BITC promoted the induction of G(2)/M phase arrest and apoptosis in A375.S2 human melanoma cells through ER stress- and mitochondria-dependent and death receptor-mediated multiple signaling pathways. These data suggest that BITC has potential as an agent for the treatment of melanoma.

Butein inhibits the migration and invasion of SK-HEP-1 human hepatocarcinoma cells through suppressing the ERK, JNK, p38, and uPA signaling multiple pathways.

Liver cancer is one of the most commonly diagnosed cancers and the leading cause of death in human populations. Butein, a tetrahydroxychalcone, has been shown to induce apoptosis in many human cancer cells, but the effects of butein on the migration and invasion of human liver cancer cells are not reported. Herein, we found that butein is effective in the suppression of migration and invasion in SK-HEP-1 human hepatocarcinoma cells by using the Matrigel cell migration assay and invasion system. The gelatin zymography assay indicated that butein inhibited the activity of matrix metalloproteinases 2 (MMP-2) and MMP-9. Western blotting analysis indicated that butein decreased the levels of MMP-2, -7, and -9, uPA, Ras, Rho A, ROCK1, ERK1/2, JNK1/2, p-p38, and p-c-Jun in SK-HEP-1 cells. Furthermore, butein inhibited the NF-κB binding activity in SK-HEP-1 cells by electrophoretic mobility shift assay. We also found that butein decreased the ERK, JNK, and p38 in SK-HEP-1 cells by in vitro kinase assay. In conclusion, this is the first study to demonstrate that butein might be a novel anticancer agent for the treatment of hepatocarcinoma through inhibiting migration and invasion.

Osthole Suppresses Fatty Acid Synthase Expression in HER2-Overexpressing Breast Cancer Cells through Modulating Akt/mTOR Pathway

While fatty acid synthase (FASN) has been shown to be expressed in many human solid tumors, FASN has also been identified in preneoplastic lesions. HER2, which has also been identified in preneoplastic breast lesions, has been shown to upregulate FASN expression. Osthole, an active constituent isolated from the fruit of Cnidium monnieri (L.) Cusson, a traditional Chinese medicine, was found to be effective in suppressing FASN expression in HER2-overexpressing breast cells. Osthole preferentially inhibited proliferation and induced apoptosis in HER2-overexpressing cancer cells. Moreover, osthole inhibited the phosphorylation of Akt and mTOR. The use of Akt-overexpression revealed that the modulation of Akt and mTOR was required for osthole-induced FASN suppression. Finally, we showed that osthole could enhance paclitaxel-induced cytotoxicity in HER2-overexpressing cancer cells. These results suggested that osthole has the potential to advance as chemopreventive or chemotherapeutic agent for cancers that overexpress HER2.

Diallyl sulfide, diallyl disulfide and diallyl trisulfide affect drug resistant gene expression in colo 205 human colon cancer cells in vitro and in vivo.

To elevate chemo-resistance of human cancer cells is a major obstacle in the treatment and management of malignant cancers. Diallyl sulfide (DAS), diallyl disulfide (DADS) and diallyl trisulfide (DATS) are presented in the Alliaceae family particularly in garlic. Although DAS, DADS and DATS have been shown to exhibit anticancer activities, there is little information on effects of these compounds on drug resistant genes in human colon cancer cells in vitro and in vivo. Herein, we are the first to show that DAS, DADS and DATS at 25 μM for 24-h and 48-h incubations promoted expression of drug resistant genes in colo 205 human colon cancer cells. In vitro experiments indicated that DATS promoted gene expression of multidrug resistant 1 (Mdr1) (p<0.05), and DAS and DADS promoted MRP3 gene expression and DATS alone stimulated gene expression of multidrug resistance-associated protein-1 (MRP1) (p<0.05) in colo 205 cells. In vivo studies demonstrated that DADS and DATS induced Mdr1 and MRP1 gene expression (p<0.05). DADS promoted MRP3 gene expression (p<0.05) as well as DADS and DATS increased MRP4 and MRP6 gene expression (p<0.05) in the colo 205 xenograft mice. Based on our in vitro and in vivo results, diallyl polysulfides (DAS, DADS and DATS) affected the gene expression of the multidrug resistance in colo 205 human colon cancer cells in vitro and in vivo.

(−)-Epigallocatechin Gallate Induces Fas/CD95-Mediated Apoptosis through Inhibiting Constitutive and IL-6-Induced JAK/STAT3 Signaling in Head and Neck Squamous Cell Carcinoma Cells

In this study, we examined the effects of several plant-derived natural compounds on head and neck squamous cell carcinoma (HNSCC) cells. The results revealed that (-)-epigallocatechin gallate (EGCG) demonstrated the most efficient cytotoxic effects on HNSCC cells. We then investigated the underlying molecular mechanism for the potent proapoptotic effect of EGCG on HNSCC. Cell apoptosis was observed in the EGCG-treated SAS and Cal-27 cells in a time- and dose-dependent manner. In concert with the caspase-8 activation by EGCG, an enhanced expression in functional Fas/CD95 was identified. Consistent with the increased Fas/CD95 expression, a drastic decrease in the Tyr705 phosphorylation of STAT3, a known negative regulator of Fas/CD95 transcription, was shown within 15 min in the EGCG-treated cells, leading to downregulation of the target gene products of STAT3, such as bcl-2, vascular endothelial growth factor (VEGF), mcl-1, and cyclin D1. An overexpression in STAT3 led to resistance to EGCG, suggesting that STAT3 was a critical target of EGCG. Besides inhibiting constitutive expression, EGCG also abrogated the interleukin-6 (IL-6)-induced JAK/STAT3 signaling and further inhibited IL-6-induced proliferation on HNSCC cells. In comparison with apigenin, curcumin, and AG490, EGCG was a more effective inhibitor of IL-6-induced proliferation on HNSCC cells. Overall, our results strongly suggest that EGCG induces Fas/CD95-mediated apoptosis through inhibiting constitutive and IL-6-induced JAK/STAT3 signaling. This mechanism may be partially responsible for EGCGs ability to suppress proliferation of HNSCC cells. These findings provide that EGCG may be useful in the chemoprevention and/or treatment of HNSCC.

Induction of DNA damage by deguelin is mediated through reducing DNA repair genes in human non-small cell lung cancer NCI-H460 cells

It has been shown that deguelin, one of the compounds of rotenoids from flavonoid family, induced cytotoxic effects through induction of cell cycle arrest and apoptosis in many types of human cancer cell lines, but deguelin-affected DNA damage and repair gene expression (mRNA) are not clarified yet. We investigated the effects of deguelin on DNA damage and associated gene expression in human lung cancer NCI-H460 cells in vitro. DNA damage was assayed by using the comet assay and DNA gel electrophoresis and the results indicated that NCI-H460 cells treated with 0, 50, 250 and 500 nM deguelin led to a longer DNA migration smear based on the single cell electrophoresis and DNA fragmentation occurred based on the examination of DNA gel electrophoresis. DNA damage and repair gene expression (mRNA) were evaluated by using real-time PCR assay and the results indicated that 50 and 250 nM deguelin for a 24-h exposure in NCI-H460 cells, decreased the gene levels of breast cancer 1, early onset (BRCA1), DNA-dependent serine/threonine protein kinase (DNA-PK), O6-methylguanine-DNA methyltransferase (MGMT), p53, ataxia telangiectasia mutated (ATM) and ataxia-telangiectasia and Rad3-related (ATR) mRNA expressions. Collectively, the present study showed that deguelin caused DNA damage and inhibited DNA damage and repair gene expressions, which might be due to deguelin-inhibited cell growth in vitro.

Induction of apoptotic death by curcumin in human tongue squamous cell carcinoma SCC-4 cells is mediated through endoplasmic reticulum stress and mitochondria-dependent pathways

Curcumin from the rhizome of the Curcuma longa plant has been noted for its chemo‐preventative and chemo‐therapy activities, and it inhibits the growth of many types of human cancer cell lines. In this study, the mechanisms of cell death involved in curcumin‐induced growth inhibition, including cell cycle arrest and induction of apoptosis in human tongue cancer SCC‐4 cells, were investigated. Herein, we observed that curcumin inhibited cell growth of SCC‐4 cells and induced cell death in a dose‐dependent manner. Treatment of SCC‐4 cells with curcumin caused a moderate and promoted the G2/M phase arrest, which was accompanied with decreases in cyclin B/CDK1 and CDC25C protein levels. Moreover, curcumin significantly induced apoptosis of SCC‐4 cells with a decrease of the Bcl‐2 level, reduction of mitochondrial membrane potential (ΔΨm), and promoted the active forms of caspase‐3. Curcumin also promoted the releases of AIF and Endo G from the mitochondria in SCC‐4 cells by using confocal laser microscope. Therefore, we suggest that curcumin induced apoptosis through a mitochondria‐dependent pathway in SCC‐4 cells. In addition, we also found that curcumin‐induced apoptosis of SCC‐4 cells was partly through endoplasmic reticulum stress. In conclusion, curcumin increased G2/M phase arrest and induced apoptosis through ER stress and mitochondria‐dependent pathways in SCC‐4 cells. Copyright

Cantharidin induces apoptosis of H460 human lung cancer cells through mitochondria-dependent pathways

Lung cancer is one of the leading causes of death in cancer-related diseases. Cantharidin (CTD) is one of the components of natural mylabris (Mylabris phalerata Pallas). Numerous studies have shown that CTD induced cytotoxic effects on cancer cells. However, there is no report to demonstrate that CTD induced apoptosis in human lung cancer cells. Herein, we investigated the effect of CTD on the cell death via the induction of apoptosis in H460 human lung cancer cells. Flow cytometry assay was used for examining the percentage of cell viability, sub-G1 phase of the cell cycle, reactive oxygen species (ROS) and Ca²⁺ productions and the levels of mitochondrial membrane potential (∆Ψm). Annexin V/PI staining and DNA gel electrophoresis were also used for examining cell apoptosis. Western blot analysis was used to examine the changes of apoptosis associated protein expression and confocal microscopy for examining the translocation apoptosis associated protein. Results indicated that CTD significantly induced cell morphological changes and decreased the percentage of viable H460 cells. CTD induced apoptosis based on the occurrence of sub-G1 phase and DNA fragmentation. We found that CTD increased gene expression (mRNA) of caspase-3 and -8. Moreover, CTD increased ROS and Ca2+ production and decreased the levels of ∆Ψm. Western blot analysis results showed that CTD increased the expression of cleavage caspase-3 and -8, cytochrome c, Bax and AIF but inhibited the levels of Bcl-xL. CTD promoted ER stress associated protein expression such as GRP78, IRE1α, IRE1β, ATF6α and caspase-4 and it also promoted the expression of calpain 2 and XBP-1, but inhibited calpain 1 that is associated with apoptosis pathways. Based on those observations, we suggest that CTD may be used as a novel anticancer agent for the treatment of lung cancer in the future.

Apigenin Induces Apoptosis through Mitochondrial Dysfunction in U-2 OS Human Osteosarcoma Cells and Inhibits Osteosarcoma Xenograft Tumor Growth in Vivo

The cytostatic drug from natural products has acted as a chemotherapeutic agent used in treatment of a wide variety of cancers. Apigenin, a type of flavonoid, exhibits anticancer actions, but there is no report to show that apigenin induced apoptosis in osteosarcoma cells. The aim of this study was to investigate the effects of apigenin on U-2 OS human osteosarcoma cells and clarify that the apigenin-induced apoptosis-associated signals. The cytotoxic effects of apigenin were examined by culturing U-2 OS cells with or without apigenin. The percentage of viable cells via PI staining, apoptotic cells, productions of ROS and Ca²⁺, and the level of mitochondrial membrane potential (ΔΨm) were assayed by flow cytometry. The levels of apoptosis-related proteins were measured by immunoblotting. Results indicated that apigenin significantly decreased cell viability. Apigenin effectively induced apoptosis through the activations of caspase-3, -8, -9, and BAX and promoted the release of AIF in U-2 OS cells. In nude mice bearing U-2 OS xenograft tumors, apigenin inhibited tumor growth. In conclusion, apigenin has anticancer properties for induction of cell apoptosis in U-2 OS cells and suppresses the xenograft tumor growth. These findings offer novel information that apigenin possibly possesses anticancer activity in human osteosarcoma.

Diallyl trisulfide inhibits migration, invasion and angiogenesis of human colon cancer HT‐29 cells and umbilical vein endothelial cells, and suppresses murine xenograft tumour growth

Angiogenesis inhibitors are beneficial for the prevention and treatment of angiogenesis‐dependent diseases including cancer. We examined the cytotoxic, anti‐metastatic, anti‐cancer and anti‐angiogenic effects of diallyl trisulfide (DATS). In HT29 cells, DATS inhibited migration and invasion through the inhibition of focal adhesion kinase (FAK), extracellular signal‐regulated kinase, c‐Jun N‐terminal kinase and p38 which was associated with inhibition of matrix metalloproteinases‐2, ‐7 and ‐9 and VEGF. In human umbilical vein endothelial cells (HUVEC), DATS inhibited the migration and angiogenesis through FAK, Src and Ras. DATS also inhibited the secretion of VEGF. The capillary‐like tube structure formation and migration by HUVEC was inhibited by DATS. The chicken egg chorioallantoic membrane (CAM) assay indicated that DATS treatment inhibited ex‐vivo angiogenesis. We investigated the anti‐tumour effects of DATS against human colon cancer xenografts in BALB/cnu/nu mice and its anti‐angiogenic activity in vivo. In this in‐vivo study, DATS also inhibited the tumour growth, tumour weight and angiogenesis (decreased the levels of haemoglobin) in HT29 cells. In conclusion, the present results suggest that the inhibition of angiogenesis may be an important mechanism in colon cancer chemotherapy by DATS.