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Our previous study found that the combination of halofuginone (HF) and artemisinin (ATS) synergistically arrest colorectal cancer (CRC) cells at the G1/G0 phase of the cell cycle; however, it remains unclear whether HF-ATS induces cell death. Here we report that HF-ATS synergistically induced caspase-dependent apoptosis in CRC cells. Specifically, both in vitro and in vivo experiments showed that HF or HF-ATS induces apoptosis via activation of caspase-9 and caspase-8 while only caspase-9 is involved in ATS-induced apoptosis. Furthermore, we found HF or HF-ATS induces autophagy; ATS can't induce autophagy until caspase-9 is blocked. Further analyzing the crosstalk between autophagic and caspase activation in CRC cells, we found autophagy is essential for activation of caspase-8, and ATS switches to activate capase-8 via induction of autophagy when caspase-9 is inhibited. When apoptosis is totally blocked, HF-ATS switches to induce autophagic cell death. This scenario was then confirmed in studies of chemoresistance CRC cells with defective apoptosis. Our results indicate that HF-ATS induces cell death via interaction between apoptosis and autophagy in CRC cells. These results highlight the value of continued investigation into the potential use of this combination in cancer therapy., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Background: Melanoma is a lethal cancer. NF-κB has been validated as a molecular target for melanoma treatment. Current therapies for melanoma have limitations. Novel targeted therapeutics are needed. Arnicolide D (Ar-D), a sesquiterpene lactone isolated from the dried whole plant of Centipeda minima (L.) A. Br. et Aschers., has been reported to inhibit NF-κB activity in colorectal cancer cells., Purpose: To investigate the anti-melanoma effects of Ar-D in vitro and in vivo; and to determine whether Ar-D inhibits the NF-κB pathway in melanoma cells., Methods: A B16F10 allograft mouse model and two melanoma cell lines (A375 and B16F10) were used to investigate the anti-melanoma effects of Ar-D in vivo and in vitro. Dacarbazine was used as a positive control. Cell viability was assessed by MTT and crystal violet staining assays. Cell cycle arrest and apoptosis were analyzed by flow cytometry. Protein levels were determined by Immunoblotting., Results: In vivo assays showed that the average tumor weight in Ar-D-treated group (4 mg/kg, i.p, 15 days) was reduced by 53.7%, when compared with the control group. In vitro studies demonstrated that Ar-D reduced cell viability, induced G2/M cell cycle arrest and apoptosis, elevated levels of cell cycle regulatory proteins p53 and p21, and lowered levels of G2/M checkpoint proteins Cdc2 and Cyclin B1 in melanoma cells. Mechanistically, Ar-D inhibited the activity of IKKα/β, the degradation of IκBα, and the phosphorylation and expression of NF-κB p65 in melanoma cells., Conclusion: Ar-D has anti-melanoma effects, and inhibition of the IKK/IκBα/NF-κB p65 pathway is involved in the effects., (Copyright © 2019 Elsevier GmbH. All rights reserved.)

Background: Sulforaphane (SFN) has been shown to induce the production of reactive oxygen species (ROS) and inhibit epidermal growth factor receptor (EGFR)-mediated signaling in non-small-cell lung cancer (NSCLC). NSCLC cells harboring constitutively active EGFR mutations are more sensitive to SFN treatment than cells with wild-type EGFR, but whether NSCLC cells with high levels of EGFR expression are more resistant or sensitive to SFN treatment is not known., Study Design: We employed a pair of cell lines, CL1-0 and CL1-5, which have the same genetic background but different levels of EGFR expression, to examine the effects of high EGFR level in the sensitivity to SFN., Methods: The effect of SFN on cell viability and tumorigenicity was examined by trypan blue dye-exclusion assay, clonogenic assays, flow cytometry, and immunoblotting in vitro as well as tumorigenicity study in vivo. ROS levels in cells were assessed by flow cytometry using the ROS-reactive fluorescent indicator CM-H2DCFDA. Knockdown of EGFR in CL1-5 cells was infected with an EGFR-targeting small hairpin (interfering) RNA (shRNA)-containing lentivirus., Results: We present evidence that cells with high-level EGFR expression (CL1-5) are more resistant to SFN treatment than those with low-level expression (CL1-0). SFN treatment produced a similar increase in ROS and caused arrest of a cell population at S-phase accompanied by the induction of γH2AX, a DNA damage-response marker, in both cell sublines. However, SFN induced apoptosis only in the high-EGFR-expressing CL1-0 subline. Pretreatment with the antioxidant N-acetyl-L-cysteine prevented SFN-induced apoptosis in CL1-0 cells and production of γH2AX in both CL1-0 and CL1-5 cells. shRNA-mediated knockdown of EGFR in CL1-5 cells rendered the cells susceptible to SFN-induced apoptosis., Conclusion: The cellular effects produced by SFN in NSCLC cells are largely mediated by SFN-induced production of ROS. Cells with higher levels of EGFR were more resistant to SFN treatment and showed resistance to SFN-induced apoptosis, suggesting that high EGFR levels protect cells from SFN-induced apoptosis. Despite this, we found that SFN retained the ability to inhibit the growth of NSCLC tumors with high-level EGFR expression in vivo., (Copyright © 2019 Elsevier GmbH. All rights reserved.)

Background: Hepatocellular carcinoma (HCC) ranks third among the most common causes of cancer-related deaths worldwide. The chemotherapy for HCC is still insufficient, so far. In searching for effective anti-HCC agents from traditional Chinese medicine, we discovered that aloperine (ALO), a quinolizidine alkaloid from Sophora alopecuroides L., exerts anti-HCC activities. However, the effects of ALO on HCC have been rarely studied, and its underlying mechanisms remain unknown., Purpose: This study aims to evaluate the anti-HCC activities of ALO and explore its underlying mechanisms., Methods: MTT assay and colony formation assay were used to investigate the anti-proliferative effects of ALO on human HCC Hep3B and Huh7 cells. Hoechst 33258 staining was used to observe the morphological changes of cells after ALO treatment. Flow cytometry was used to analyze apoptosis induction, the collapse of the mitochondrial membrane potential and cell cycle distribution. Western blotting was used to examine the expression levels of proteins associated with apoptosis and cell cycle arrest, and key proteins in the PI3K/Akt signaling pathway. Small interfering RNA (siRNA) transfection was used to investigate the role of Akt in ALO-induced apoptosis and cell cycle arrest. Zebrafish tumor model was used to evaluate the anti-HCC effects of ALO in vivo., Results: ALO inhibited the proliferation of Hep3B and Huh7 cells. ALO induced apoptosis in HCC cells, which was accompanied by the loss of mitochondrial potential, the release of cytochrome c into cytosol, as well as the increased cleavages of caspase-9, caspase-3 and PARP. Moreover, ALO induced G2/M cell cycle arrest by downregulating the expression levels of cdc25C, cdc2 and cyclin B1. In addition, ALO inhibited activation of the PI3K/Akt signaling pathway by decreasing the expression levels of p110α, p85, Akt and p-Akt (Ser473) . Further study showed that inhibition of Akt by siRNA augmented ALO-mediated apoptosis and G2/M cell cycle arrest in HCC cells. Critically, ALO inhibited the growth of Huh7 cells in vivo., Conclusion: We first demonstrated that ALO induced apoptosis and G2/M cell cycle arrest in HCC cells through inhibition of the PI3K/Akt signaling pathway. This study provides a rationale for ALO as a potential chemotherapeutic agent for HCC., (Copyright © 2019 Elsevier GmbH. All rights reserved.)

Non-thermal plasma (NTP) treatment has been proposed as a potential approach for cancer therapy for killing cancer cells via generation of reactive oxygen species (ROS). As an antioxidant protein, Heme oxygenase-1 (HO-1) has been known to protect cells against oxidative stress. In this paper, we investigated the role of HO-1 activation in NTP-induced apoptosis in A549 cells. Distinctly increased ROS production and apoptosis were observed after NTP exposure. NTP exposure induced HO-1 expression in a dose- and time-dependent manner via activating the translocation of Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) from cytoplasm to nucleus. Furthermore, inhibiting HO-1 activation with its specific inhibitor, ZnPP, increased "killing" effect of NTP. Knocking down HO-1 or Nrf2 with the special siRNA also led to elevated ROS level and enhanced NTP-induced cell death. In addition, the c-JUN N-terminal kinase (JNK) signaling pathway was shown to be involved in NTP-induced HO-1 expression. Interestingly, a higher resistance to NTP exposure of A549 cell compared to H1299 and H322 cells was found to be linked to its higher basal level of HO-1 expression. These findings revealed that HO-1 could be considered as a potential target to improve the effect of NTP in cancer therapy., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Background/aims: 2-O-methylmagnolol (MM1), a derivative of magnolol bearing one methoxy moiety, has been shown to display improved anti-tumor activity against skin cancers. In this study, we examined the anti-tumor effects of magnolol and MM1 on oral squamous cell carcinoma (OSCC)., Methods: Trypane blue staining and clonogenic assays were performed to determine the cytotoxic effects of magnolol and MM1 in OSCC cells. Migration and matrigel invasion assays were carried out to examine the metastasis effects of magnolol and MM1 in OSCC cells. IL6-stimulation, Western blot, and immunohistochemistry were used to investigate the IL-6/STAT3 signaling and apoptosis. A bioluminescent mouse model of orthotopically implanted SAS cells was used to determine the anti-tumor activity of MM1 in vivo., Results: MM1 displays greater activity than magnolol on affecting the cytotoxicity, migration, and invasion of OSCC cells cultured in vitro. The improved anti-tumor activity of MM1 was shown to associate with its greater activity to inhibit STAT3 signaling and to induce apoptosis in the OSCC. In addition, we presented evidence that MM1 is effective in inhibiting the growth of orthotopic implanted OSCC cells in vivo., Conclusion: Our data indicate that MM1 displays greater anti-tumor activity than magnolol in OSCC and is an attractive agent to be further explored for its potential clinical application., (© 2018 The Author(s). Published by S. Karger AG, Basel.)

Non-thermal plasma (NTP) has been proposed as a novel therapeutic method for anticancer treatment. Although increasing evidence suggests that NTP selectively induces apoptosis in some types of tumor cells, the molecular mechanisms underlying this phenomenon remain unclear. In this study, we further investigated possible molecular mechanisms for NTP-induced apoptosis of HeLa cells. The results showed that NTP exposure significantly inhibited the growth and viability of HeLa cells. Morphological observation and flow cytometry analysis demonstrated that NTP exposure induced HeLa cell apoptosis. NTP exposure also activated caspase-9 and caspase-3, which subsequently cleaved poly (ADP- ribose) polymerase. Furthermore, NTP exposure suppressed Bcl-2 expression, enhanced Bax expression and translocation to mitochondria, activated mitochondria-mediated apoptotic pathway, followed by the release of cytochrome c. Further studies showed that NTP treatment led to ROS generation, whereas blockade of ROS generation by N-acetyl-l-cysteine (NAC, ROS scavengers) significantly prevented NTP-induced mitochondrial alteration and subsequent apoptosis of HeLa cells via suppressing Bax translocation, cytochrome c and caspase-3 activation. Taken together, our results indicated that NTP exposure induced mitochondria-mediated intrinsic apoptosis of HeLa cells was activated by ROS generation. These findings provide insights to the therapeutic potential and clinical research of NTP as a novel tool in cervical cancer treatment., (Copyright © 2017. Published by Elsevier Inc.)

The JAK2/STAT3 signaling pathway plays a critical role in tumorigenesis, and has been suggested as a potential molecular target for anti-melanoma therapeutics. However, few JAK2 inhibitors were being tested for melanoma therapy. In this study, eight amentoflavone analogues were evaluated for their activity against human malignant melanoma cells. The most potent analogue, compound 1, inhibited the phosphorylation of JAK2 and STAT3 in human melanoma cells, but had no discernible effect on total JAK2 and STAT3 levels. A cellular thermal shift assay was performed to identify that JAK2 is engaged by 1 in cell lysates. Moreover, compound 1 showed higher antiproliferative activity against human melanoma A375 cells compared to a panel of cancer and normal cell lines. Compound 1 also activated caspase-3 and cleaved PARP, which are markers of apoptosis, and suppressed the anti-apoptotic Bcl-2 level. Finally, compound 1 induced apoptosis in 80% of treated melanoma cells. To our knowledge, compound 1 is the first amentoflavone-based JAK2 inhibitor to be investigated for use as an anti-melanoma agent.

Magnolol, a hydroxylated biphenol compound isolated from the bark of Magnolia officinalis, has been shown to exhibit anti-proliferative effect in various cancer cells, including skin cancer cells. Methoxylation of magnolol appears to improve its anti-inflammatory activity, yet the effect of this modification on the agent's antitumor activity remains unknown. In this work, we report that 2-O-methylmagnolol (MM1) displays improved antitumor activity against skin cancer cells compared to magnolol both in vitro and in vivo. The increased antitumor activity of MM1 appears to correlate with its increased ability to induce apoptosis. DNA microarray and network pathway analyses suggest that MM1 affects certain key factors involved in regulating apoptosis and programmed cell death. Interestingly, the level of the long non-coding (lnc) RNA of growth arrest-specific 5 (GAS5) was increased in MM1-treated cells, and inhibition of lncRNA GAS5 inhibited MM1-induced apoptosis. Conversely, overexpression of lncRNA GAS5 inhibited cell proliferation and promoted cell apoptosis in skin cancer cells. The expression of lncRNA GAS5 in the skin cancer tissues was found to be lower than that in the adjacent normal tissues in a majority of patients. Taken together, our findings suggest that MM1 has improved antitumor activity in skin cancer cells, and that this is due, at least in part, to the upregulation of lncRNA GAS5 and the enhancement of apoptosis.

Signal transducer and activator of transcription 3 (STAT3) is a potential drug target for chemotherapy. Cryptotanshinone (CTS) was identified as a potent STAT3 inhibitor, while the effect of other tanshinones remains unknown. In this study, the influence of eight tanshinones on STAT3 activity was initially screened and isocryptotanshinone (ICTS) significantly inhibited STAT3 activity in a dual luciferase assay. ICTS inhibited the constitutive and inducible phosphorylation of STAT3 at Y705 without affecting the phosphorylation of STAT3 at S727 in A549 lung cancer cells. Furthermore, ICTS inhibited the nuclear translocation of STAT3. Compared with CTS, ICTS exhibited a stronger inhibitory effect on STAT3 phosphorylation and on A549 cytotoxicity. ICTS induced autophagy as evidenced by the accumulation of autophagic vacuoles and the increased expression of LC3 protein and autophagosomes. ICTS-induced cell death was partially reversed by the autophagy inhibitor chloroquine. The docking assay predicted that both ICTS and CTS bind the SH2 domain of STAT3. ICTS formed hydrogen bonds and pi-pi interaction with the nearby amino acid residues of Lys591, Arg609, and Ser636. These findings suggested that ICTS, a natural compound, is a potent STAT3 inhibitor. ICTS induced apoptosis and pro-death autophagy in A549 cells.

AKT is the frequently overexpressed and constitutively active kinase within NSCLC cells and recognized as a promising target for NSCLC treatment. However, AKT inhibition relieves the feedback inhibition of upstream receptor tyrosine kinases (RTKs) that may weaken the efficiency of AKT inhibitors. Platycodin D (PD), isolated from widely-used traditional Chinese medicine Platycodonis Radix, is now found to remarkably enhance the anti-proliferative effect of AKT inhibitors. In this study, combinatorial activity of AKT inhibitor MK2206 and PD on cell proliferation, apoptosis and related signaling were disclosed. Long-term AKT inhibition induced up-regulation of RTKs, including EGFR and HER-2. Co-treatment of MK2206 with PD could abolish this feedback survival through decrease of EGFR, HER-2, and p-AKT, and profound inhibition of 4E-BP1, leading to an amplified anti-proliferative and apoptotic activity in NSCLC cells. Similarly, feedback activation in response to reduction of AKT expression by small interfering RNA (siRNA) was also blocked by PD and apoptotic effect was further enhanced. Thus, PD potentiated proliferative inhibition and apoptotic induction of both AKT inhibitor and siRNA. These findings also reveal the limitations of suppressing feedback-regulated pathways by monotherapy and establish a mechanistic rationale for a novel combination approach targeting AKT for the treatment of NSCLC.

Cucurbitacin E (CuE) is a triterpenoid with potent anticancer activities while the underlying mechanisms remain elusive. In the present study, the anticancer effects of CuE on 95D lung cancer cells were investigated. CuE decreased cell viability, inhibited colony formation, and increased reactive oxygen species (ROS) in a concentration-dependent manner, which were reversed by N-acetyl-l-cysteine (NAC). CuE induced apoptosis as determined by JC-1 staining, expression of Bcl-2 family proteins, cleavage of caspases, and TUNEL staining. NAC and Ac-DEVD-CHO partially reversed CuE-induced cleavage of caspase-3, caspase-7, and PARP. Furthermore, CuE caused accumulation of autophagic vacuoles and concentration- and time-dependent expression of LC3II protein. Autophagy inhibitors chloroquine and bafilomycin A1 enhanced CuE-induced LC3II expression and cell death. CuE-triggered protein expression of p-AKT, p-mTOR, Beclin-1, and p-ULK1 was partially reversed by NAC pretreatment. In addition, CuE treatment damaged F-actin without affecting β-tubulin as confirmed by immunofluorescence. In conclusion, CuE induced ROS-dependent apoptosis through Bcl-2 family and caspases in 95D lung cancer cells. Furthermore, CuE induced protective autophagy mediated by ROS through AKT/mTOR pathway. This study provides novel roles of ROS in the anticancer effect of CuE., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Background: Isoliquiritigenin (ISL), a natural compound extracted from licorice, has chemopreventive and antitumor activities. The purpose of this study was to investigate the anticancer effect of ISL on human oral squamous cell carcinoma (OSCC)., Methods: The anti-OSCC effects of ISL were evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide test, flow cytometry, reverse transcription-polymerase chain reaction, Western blotting, promoter activity, terminal deoxynucleotidyl transferase dUTP nick-end labeling assay, malignant phenotype analysis, microRNA, and xenografting., Results: ISL induced OSCC cell cycle G2/M phase arrest, apoptosis, and DNA damage. However, the DNA repair-associated ataxia telangiectasia mutated (ATM) and phospho-ATM were downregulated, ATM mRNA remained unchanged, and the downstream signals were inhibited. ATM recovered when the caspase activity was blocked by Z-DVED-FMK. A low dose of ISL inhibited OSCC malignancy in vitro and reduced the tumor size in vivo., Conclusion: ATM was cleaved by ISL-activated caspase, thus inhibiting DNA repair in OSCC cells. Therefore, ISL is a promising chemopreventive agent against oral cancer. © 2015 Wiley Periodicals, Inc. Head Neck 38: E360-E371, 2016., (© 2015 Wiley Periodicals, Inc.)

Aim: Platycodin D, the main saponin isolated from Chinese herb Platycodonis Radix, exhibits anticancer activities against various cancer cell lines. Here we evaluated its anticancer action against human hepatocellular carcinoma cells in vitro and in vivo, and elucidated the relationship between platycodin D-induced apoptosis and autophagy., Methods: The viability of human hepatocellular carcinoma BEL-7402 cells was evaluated with MTT assay, and the apoptosis was examined using Annexin V/PI and Hoechst 33342 staining assays. Monodansylcadaverine (MDC) staining was used to label autophagic vacuoles. The proteins were detected using Western blot analysis. For studying its anticancer action in vivo, platycodin D (5 and 10 mg· kg(-1)·d(-1)) was intraperitoneally injected to BEL-7402-bearing mice for 21 days., Results: Platycodin D (5-40 μmol/L) inhibited the cell proliferation in vitro with IC50 values of 37.70±3.99, 24.30±2.30 and 19.70±2.36 μmol/L at 24, 48 and 72 h, respectively. Platycodin D (5-20 μmol/L) dose-dependently increased BEL-7402 cell apoptosis, increased the Bax/Bcl-2 ratio and the levels of cleaved PARP and cleaved caspase-3, and decreased the level of Bcl-2. Furthermore, platycodin D (5-20 μmol/L) induced autophagy in BEL-7402 cells, as evidenced by formation of cytoplasmic vacuoles, increased amounts of LC3-II, and increased numbers of MDC-positive cells. Pretreatment with the autophagy inhibitor chloroquine (5 μmol/L) or BAF (50 nmol/L) significantly enhanced platycodin D-induced proliferation inhibition and apoptosis. Moreover, platycodin D (20 μmol/L) activated the ERK and JNK pathways in BEL-7402 cells, and simultaneous blockage of the two pathways effectively suppressed platycodin D-induced autophagy and enhanced platycodin D-induced apoptosis. In BEL-7402-bearing mice, platycodin D (10 mg·kg(-1)•d(-1)) significantly reduced relative tumor volume with decreased body weight., Conclusion: Platycodin D not only inhibits the proliferation of BEL-7402 cells but also suppresses BEL-7402 xenograft tumor growth. Platycodin D-induced cell proliferation inhibition and apoptosis are amplified by co-treatment with autophagy inhibitors.

Macrophage survival is believed to be a contributing factor in the development of early atherosclerotic lesions. Dysregulated apoptosis of macrophages is involved in the inflammatory process of atherogenesis. Apigenin is a flavonoid that possesses various clinically relevant properties such as anti-inflammatory, antiplatelet, and antitumor activities. Here we showed that apigenin attenuated atherogenesis in apoE (-/-) mice in an in vivo test. In vitro experiments suggested that apigenin induced apoptosis of oxidized low density lipoprotein- (OxLDL-) loaded murine peritoneal macrophages (MPMs). Proteomic analysis showed that apigenin reduced the expression of plasminogen activator inhibitor 2 (PAI-2). PAI-2 has antiapoptotic effects in OxLDL-loaded MPMs. Enhancing PAI-2 expression significantly reduced the proapoptosis effects of apigenin. Molecular docking assay with AutoDock software predicted that residue Ser473 of Akt1 is a potential binding site for apigenin. Lentiviral-mediated overexpression of Akt1 wild type weakened the proapoptosis effect of apigenin in OxLDL-loaded MPMs. Collectively, apigenin executes its anti-atherogenic effects through inducing OxLDL-loaded MPMs apoptosis. The proapoptotic effects of apigenin were at least partly attributed to downregulation of PAI-2 through suppressing phosphorylation of AKT at Ser473.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) selectively induces apoptosis and kills cancer cells but not normal cells. However, TRAIL resistance due to low level of TRAIL receptor expression is widely found in cancer cells and hampers its development for cancer treatment. Thus, the agents that can sensitize the tumor cells to TRAIL-mediated apoptosis are urgently needed. We investigated whether tanshinones, the major bioactive compounds of Salvia miltiorrhiza (danshen), can up-regulate TRAIL receptor expression. Among the major tanshinones being tested, cryptotanshinone (CT) showed the best ability to induce TRAIL receptor 2 (DR5) expression. We further showed that CT was capable of promoting TRAIL-induced cell death and apoptosis in A375 melanoma cells. CT-induced DR5 induction was not cell type-specific, as DR5 induction was observed in other cancer cell types. DR5 knockdown abolished the enhancing effect of CT on TRAIL responses. Mechanistically, induction of the DR5 by CT was found to be p53-independent but dependent on the induction of CCAAT/enhancer-binding protein-homologous protein (CHOP). Knockdown of CHOP abolished CT-induced DR5 expression and the associated potentiation of TRAIL-mediated cell death. In addition, CT-induced ROS production preceded up-regulation of CHOP and DR5 and consequent sensitization of cells to TRAIL. Interestingly, CT also converted TRAIL-resistant lung A549 cancer cells into TRAIL-sensitive cells. Taken together, our results indicate that CT can potentiate TRAIL-induced apoptosis through up-regulation of DR5.

Unlabelled: Death evasion is crucial for both carcinogenesis and resistance to anticancer therapies. Recently, we identified nucleophosmin (NPM) as a key factor counteracting death stimuli in human hepatocellular carcinoma (HCC) cells. Here we report the identification of a novel NPM-BCL2-associated X protein (BAX) pathway orchestrating death evasion in human HCC cells. Silencing of NPM expression significantly sensitized HCC cells-particularly those bearing inactivated p53 gene (Huh7, Hep3B, and Mahlavu)-to ultraviolet irradiation, mitomycin C, doxorubicin, cisplatin, sorafenib, and lapatinib. This sensitizing effect was not changed further, as p53 expression had been simultaneously silenced. Following cell stress, NPM and BAX were induced and exported out of the nucleoli and nucleus, respectively. BAX was translocated to cytoplasm in cells with relatively high NPM level, or accumulated in the mitochondria in cells with relatively low NPM level and undergoing apoptosis. Subcellular fractionation revealed that silencing of NPM expression greatly enhanced mitochondrial translocation and oligomerization of BAX in Huh7 and Mahlavu cells. In situ proximity ligation assays and reciprocal co-immunoprecipitation revealed a direct interaction between NPM and BAX in the cytoplasm. Silencing of BAX expression abolished the sensitization effect exerted by silencing of NPM in HCC cells. Clinically, up-regulation of NPM was significantly associated with advanced tumor stage and poor prognosis., Conclusion: By directly blockading BAX mitochondrial translocation and activation, NPM helps human HCC cells evade death induction independently of p53-mediated cell death. Silencing of NPM significantly sensitized HCC cells to anticancer therapies. NPM is a potential cotarget in combination with other therapies for HCC, particularly those that harbor inactivated p53 gene. Our findings are of clinical significance because NPM up-regulation and p53 mutations are usually found in advanced human cancers, including HCC., (Copyright © 2012 American Association for the Study of Liver Diseases.)

Pancreatic cancer is a highly aggressive malignant disease. Gemcitabine is currently the standard first-line chemotherapeutic agent for pancreatic cancer. As members of apoptosis inhibitors, Survivin and XIAP play an important role in chemotherapy resistance in pancreatic cancer. Emodin has therapeutic potential against cancers. This study was designed to investigate whether combination therapy with gemcitabine and emodin enhanced antitumor efficacy in pancreatic cancer. The application of the combination therapy triggered significantly higher frequency of pancreatic cancer cell apoptosis. Our research demonstrated that the combination of emodin and gemcitabine resulted in significantly reduced tumor volumes compared to gemcitabine or emodin treatment alone. Immunohistochemistry and western immunoblot analyses showed that Survivin and XIAP expression were downregulated in emodin and the combination groups compared to the other two groups. Reverse transcriptase polymerase chain reaction analyses showed that Survivin and XIAP mRNA expression in emodin and the combination groups were downregulated significantly compared to the other two groups. Furthermore, the expression of the nuclear transcription factor κB (NF-κB) protein and NF-κB mRNA were downregulated in the emodin and the combination groups. DNA-binding activity of NF-κB was inhibited in emodin and combination groups compared to the other groups. This study suggests that emodin potentiates the antitumor effects of gemcitabine in PANC-1 cell xenografts via promotion of apoptosis and IAP suppression.

Background: Emodin has been showed to induce apoptosis of pancreatic cancer cells and inhibit tumor growth in our previous studies. This study was designed to investigate whether emodin could inhibit the angiogenesis of pancreatic cancer tissues and its mechanism., Methodology/principal Finding: In accordance with our previous study, emodin inhibited pancreatic cancer cell growth, induced apoptosis, and enhanced the anti-tumor effect of gemcitabine on pancreatic caner cells in vitro and in vivo by inhibiting the activity of NF-κB. Here, for the first time, we demonstrated that emodin inhibited tumor angiogenesis in vitro and in implanted pancreatic cancer tissues, decreased the expression of angiogenesis-associated factors (NF-κB and its regulated factors VEGF, MMP-2, MMP-9, and eNOS), and reduced eNOS phosphorylation, as evidenced by both immunohistochemistry and western blot analysis of implanted tumors. In addition, we found that emodin had no effect on VEGFR expression in vivo., Conclusions/significance: Our results suggested that emodin has potential anti-tumor effect on pancreatic cancer via its dual role in the promotion of apoptosis and suppression of angiogenesis, probably through regulating the expression of NF-κB and NF-κB-regulated angiogenesis-associated factors.

Pancreatic adenocarcinoma is one of the most common malignancies worldwide. Gemcitabine is currently the standard first-line chemotherapeutic agent for pancreatic cancer. However, gemcitabine can induce activation of Akt and nuclear factor-κB (NF-κB), which is associated with its chemoresistance. It has been reported that gemcitabine combination therapies result in improved survival outcomes in pancreatic cancer. Therefore, agents that can either enhance the effects of gemcitabine or overcome chemoresistance to the drug are needed for the treatment of pancreatic cancer. Emodin is an active component of Chinese medicinal herbs and can inhibit the activation of Akt and NF-κB. In this study, we investigated whether emodin could enhance the anticancer effect of gemcitabine on pancreatic cancer in vivo. We demonstrated that treatment of gemcitabine combined with emodin efficiently suppressed tumor growth in mice inoculated with pancreatic tumor cells. This treatment paradigm promoted apoptotic cell death and mitochondrial fragmentation. Furthermore, it reduced phosphorylated-Akt (p-Akt) level, NF-κB activation and Bcl-2/Bax ratio, increased caspase-9 and -3 activation, Cytochrome C (CytC) release occurred in combination therapy. Collectively, emodin enhanced the activity of gemcitabine in tumor growth suppression via inhibition of Akt and NF-κB activation, thus promoting the mitochondrial-dependent apoptotic pathway. Therefore, our findings may provide new insights into understanding the pharmacological regulation of emodin on gemcitabine-mediated proapoptosis in pancreatic cancer and may aid in the design of new therapeutic strategies for the intervention of human pancreatic cancers.

Purpose: Overexpression of EGFR and HER2 is seen in breast cancers and results in poor prognosis and decreased patient survival. Clinically, EGFR and HER2 are effective therapeutic targets. The objective of this study is to investigate the in vitro effects of furanodienone, an active chemical component isolated from Rhizoma Curcumae, on the activation of EGFR/HER2 signaling, cell cycle, and apoptosis in HER2-overexpressing BT474 and SKBR3 cells., Methods: Cell growth was assessed by SRB protein assay. Cell cycle analysis was carried out by flow cytometry, and apoptosis was observed by Annexin V and DAPI staining. Effects of furanodienone on the activation of EGFR/HER2 signaling-related proteins were analyzed by western blotting., Results: Furanodienone inhibited cell growth in BT474 and SKBR3 cells. Furanodienone caused G1 arrest in BT474 cells and induced apoptosis in SKBR3 cells. Furanodienone interfered with EGFR/HER2 signaling in treated cells as shown by decreases in phosphorylated EGFR, HER2, Akt, Gsk3β and an increase in p27(kip1) protein. Accordingly, furanodienone inhibited EGF-induced phosphorylation of EGFR, HER2, Akt, and Gsk3β. EGFR-specific siRNA knockdown did not affect the cell growth inhibitory effect of furanodienone. On the contrary, specific siRNA knockdown of HER2 increased cellular resistance to furanodienone toxicity. In HER-2-deficient MDA-MB-231 cells, the transfection and expression of HER2 increased the sensitivity of cells to furanodienone toxicity., Conclusion: Furanodienone inhibited EGFR/HER2 signaling pathway in BT474 and SKBR3 cells. More importantly, the effect of furanodienone was specifically dependent on HER2, but not EGFR, expression.

Ethnopharmacological Relevance: Panax ginseng is a precious traditional Chinese herbal medicine which has been utilized as herbal tonic for improving immunity. The active component, ginsenosides have been shown to possess various pharmacological functions including immunomodulation and cardiovascular protection., Aim of the Study: To investigate the immunomodulatory effect and anti-apoptotic effect of ginsenosides on avian influenza-infected human endothelial cells, and to present evidence for the cardiovascular protection by ginseng during influenza infection., Materials and Methods: Human umbilical vein endothelial cells (HUVECs) were infected with avian influenza H9N2/G1 to induce IP-10 production and cell death, cells were then incubated with ginsenosides PPT and Re. The level of IP-10 and microRNA was determined by ELISA and real-time PCR respectively. Cell death was determined by MTT, TUNEL and flow cytometry., Results: Ginsenoside metabolite protopanaxatriol showed significant suppression effect on IP-10 production upon H9N2/G1 infection through up-regulation of miR-15b expression. In addition, ginsenoside-induced cytoprotection was reflected in the increase of cell viability. Data from flow cytometry analysis and TUNEL assay also showed that ginsenoside Re could protect ECs from H9N2/G1-induced apoptosis and DNA damage., Conclusions: This report further supports the traditional belief for immunomodulatory effects of ginseng, also demonstrated the partial protective mechanism of ginsenosides on avian influenza infection and its related endothelial dysfunction., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

Ethnopharmacological Relevance: Atractylenolide II (AT-II) is a sesquiterpene compound isolated from the dried rhizome of Atractylodes macrocephala (Baizhu in Chinese), which is traditionally prescribed for melanoma treatment by Chinese medicine practitioners. Our previous study showed that AT-II can inhibit B16 cells proliferation. Here we investigate the mechanistic basis for the anti-proliferative activity of AT-II in B16 melanoma cells., Materials and Methods: Cell viability was examined by MTT assay. Cell cycle distribution and apoptosis were determined by flow cytometry. Protein expression was determined by Western blotting., Results: AT-II treatment for 48 h dose-dependently inhibited cell proliferation with an IC(50) of 82.3 μM, and induced G1 phase cell cycle arrest. Moreover, treatment with 75 μM AT-II induced apoptosis. These observations were associated with the decrease of the expression of Cdk2, phosphorylated-Akt, phosphorylated-ERK and Bcl-2, the increase of the expression of phosphorylated-p38, phosphorylated-p53, p21, p27, and activation of caspases-8, -9 and -3. In addition, a chemical inhibitor of p53, PFTα, significantly decreased AT-II-mediated growth inhibition and apoptosis., Conclusions: We demonstrated that the G1-arresting and apoptotic effects of AT-II in B16 cells involve p38 activation as well as ERK and Akt inactivation, and the cytotoxic/apoptotic effects of AT-II are potentially p53 dependent. These findings provided chemical and pharmacological basis for the traditional application of Baizhu in melanoma treatment., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

Objective: To explore the effect of emodin combined gemcitabine (E&G) on human pancreatic cancer cell line BxPC-3 in vitro., Methods: BxPC-3 cells were treated with emodin alone in different concentrations (0, 10, 20, 40, 80, and 160 micromol/L, respectively) for 24, 48, and 72 h, and E&G (emodin 40 micromol/L + gemcitabine 20 micromol/L) for 72 h. The inhibition on BxPC-3 cell proliferation was detected by Cell Counting Kit-8 assay and the cell apoptosis of BxPC-3 was determined using flow cytometry., Results: Emodin obviously suppressed the proliferation of BxPC-3 cells in a dose- and time-dependent manner. The survival rates of BxPC-3 cells by 40 micromol/L emodin for 24, 48, and 72 h were 79. 39%, 46. 35%, and 45. 44%, respectively, while the survival rate of BxPC-3 cells acted by 72-h E&G was only 26. 62%, showing significant difference from that by gemcitabine alone (42.78%) and the emodin alone (47.18%). The early apoptotic ratio of BxPC-3 cells induced by 24 h emodin (40 micromol/L) and gemcitabine (20 micromol/L) were 4.70% +/- 1.54% and 11.20% +/- 1.41% respectively, while early apoptotic ratio of BxPC-3 cells induced by E&G was 20.60% +/-3.23%, showing significant difference from that induced by emodin or gemcitabine alone (P<0.05)., Conclusions: Emodin could significantly inhibit BxPC-3 cell growth. It could act synergistically with gemcitabine to inhibit the tumor proliferation of BxPC-3 cells. Its synergistic action was achieved mainly through inducing pancreatic cancer cell apoptosis.

Oridonin, the main active constituent of Isodon rubescen, has antihepatocarcinoma activity in experimental and clinical settings. The aims of the study were to explore the anticancer effect of oridonin in HepG2 cells and to investigate the underlying mechanisms. Results showed that oridonin treatment for 24 or 48 h resulted in a marked decrease in cell viability time- and dose-dependently. IC50 values were determined as 38.86 microM and 24.90 microM for 24-h and 48-h treatments, respectively. Flow cytometric analysis showed that a 24-h treatment of 40 microM oridonin induced G2/M cell cycle arrest and apoptosis. Typical apoptotic nucleus alterations were observed with fluorescence microscope after DAPI staining. Immunoblot analysis demonstrated that oridonin treatment increased expression levels of p-JNK, p-p38, p-p53 and p21, elevated the level of cyclin B1/p-Cdc2 (Tyr15) complex, and inhibited the expression of p-ERK. Moreover, oridonin treatment activated caspase-9 and caspase-3. In conclusion, oridonin induced G2/M cell cycle arrest and apoptosis in HepG2 cells through MAPK and p53 pathways, which advances our understanding on the molecular mechanisms of oridonin in hepatocarcinoma management.

1. In the present study, we investigated the immunosuppressive effects and mechanisms of action of emodin on acute graft rejection following liver transplantation in a rat model of orthotopic liver transplantation. 2. Rats were divided into three groups: Group A, syngenic control (Brown Norway-to-Brown Norway); Group B, acute rejection group (Lewis-to-Brown Norway); and Group C, emodin-treated group (Lewis-to-Brown Norway treated with 50 mg/kg emodin, 50 mg/kgxd, injected intraperitoneally once a day from days 1 to 5 posttransplantation). The survival time of the recipients in each group was recorded. Histopathological changes in the liver, hepatocellular apoptosis, serum concentrations of interleukin (IL)-2, interferon (IFN)-gamma and IL-4 and their expression in liver tissue were determined. 3. Emodin treatment prolonged liver allograft survival time from 10.9 days in Group B to 25.6 days in Group C. The rejection activity index (calculated according to the Banff Schema) in Groups A, B and C was 1.29 +/- 0.47, 7.58 +/- 0.85 and 4.72 +/- 0.79, respectively (P < 0.01 for Groups A and B vs Group C), whereas the apoptosis index in the three groups was 15.51 +/- 1.47, 39.50 +/- 1.65 and 16.72 +/- 1.73, respectively (P < 0.01 for Groups A and C vs Group B). Serum levels of IL-2 and IFN-gamma were higher, whereas levels of IL-4 were lower, in the acute rejection group (Group B) than in the emodin-treated group (Group C; P < 0.05). Changes in the expression of these cytokines in transplanted liver tissue were consistent with changes in serum concentrations. 4. In conclusion, emodin effectively suppresses acute graft rejection in vivo to prolong the survival of recipient rats. The mechanism underlying this effect may be associated with the prevention of hepatocyte apoptosis and with a changing in the balance of Th1/Th2 cytokines towards Th2.

Dechorionated zebrafish embryos were irradiated at 1.5 h post fertilization (hpf) to low-doses of alpha particles, viz., 1.4, 2.8, 5.6, 11.2 mGy (determined using Monte Carlo simulations). At 24 hpf, these embryos were then examined for apoptotic cells through acridine orange staining. The mean number of apoptotic cells was found to decrease significantly from controls to 1.4-mGy irradiation, and then to increase almost linearly to 2.8, 5.6 and 11.2-mGy irradiation. This trend is a typical characteristic of a hormetic effect., (Copyright 2009 Elsevier Ltd. All rights reserved.)

Formononetin is a novel herbal isoflavonoid isolated from Astragalus membranaceus, a medicinal plant that possesses antitumorigenic property. We attempted to compare the anticarcinogenic mechanism of formononetin with that of the known proapoptotic flavonoid isoliquiritigenin (ISL) in human cancer cells. We first evaluated the effects of formononetin and ISL on HCT 116 colon cancer cell viability. Immunofluorescence staining was then performed to observe the morphological changes of cancer cells undergoing apoptosis, which had been substantiated using Annexin V-FITC/propidium iodide staining. Western immunoblotting and flow cytometry were also employed to study parameters associated with apoptosis and cell proliferation. Our data show that formononetin and ISL both inhibited the growth of colon cancer cells and promoted apoptosis. These processes were accompanied by caspase activation and downregulation of the antiapoptotic proteins Bcl-2 and Bcl-x(L). Besides, the novel proapoptotic protein NSAID-activated gene (NAG-1) and its upstream regulator were overexpressed in drug-treated cells. Nevertheless, only ISL was found to induce a G2 arrest. These findings exemplify that both formononetin and ISL could cause growth inhibition and facilitate apoptosis in colon cancer cells, while only ISL is capable of inducing phase-specific cell cycle arrest. This suggests that the anticarcinogenic activities of different herbal flavonoids may involve both common and differential mechanisms of action, which could be developed as potential anticancer drugs.

Ginsenosides, the active components of the famous Chinese herb ginseng, have been suggested to possess cardiovascular-protective effects. The mechanism of ginsenosides is believed to be associated with their ability to prevent cellular oxidative stress. The purpose of this study was to explore the cytoprotective effects of the ginsenoside protopanaxatriol (PPT) on hydrogen peroxide (H(2)O(2))-induced endothelial cell injury and cell death. Pretreatment of human umbilical vein endothelial cells (HUVECs) with PPT for 24 h was able to protect the cells against H(2)O(2)-induced injury. In addition to cell death, pretreatment with PPT could also reduce H(2)O(2)-induced DNA damage, overactivation of the DNA repair enzyme PARP-1, and concomitant depletion of the intracellular substrate NAD(+). Furthermore, PPT could reverse the decrease in ATP/ADP ratio caused by H(2)O(2). The metabolism of glutathione was also changed. H(2)O(2) could induce a significant decrease in GSH level resulting in a decrease in the GSH/GSSG ratio. This could be prevented by pretreatment with PPT. The action was associated with increasing activities of the GSH-metabolizing enzymes glutathione reductase and glutathione peroxidase. These findings suggest that the ginsenoside PPT could protect HUVECs against H(2)O(2)-induced cell death via its action against oxidative stress, which may be responsible for the cardiovascular-protective action of ginseng., (Copyright 2009 Elsevier Inc. All rights reserved.)

The present study aims to determine the role of mitogen-activated protein kinases (MAPKs) in hypericin-mediated photodynamic therapy (HY-PDT)-induced apoptosis of the HK-1 nasopharyngeal carcinoma (NPC) cells. HY-PDT was found to induce proteolytic cleavage of procaspase-9 and -3 in HK-1 cells. Apoptotic nuclei were observed at 6 h after PDT whereas B-cell leukemia/lymphoma-2-associated-X-protein (Bax) translocation and formation of Bax channel is responsible for the cell death. Increase in phosphorylation of p38 MAPKs and c-Jun N-terminal kinase 1/2 (JNK1/2) was detected at 15-30 min after HY-PDT. The appearance of phosphorylated form of p38 MAPKs and JNK1/2 was inhibited by the singlet oxygen scavenger l-histidine. HY-PDT-induced cell death was enhanced by the chemical inhibitors for p38 MAPKs (SB202190 and SB203580), but not by the JNKs inhibitor SP600125. Knockdown of the p38alpha and p38beta MAPK isoforms by small interfering RNA (siRNA) are more effective than the p38delta in enhancing PDT-induced cell death. Augmentation of apoptosis by p38alpha or p38beta knockdown is also correlated with the increased proteolytic cleavage of procaspase-9 after HY-PDT treatment. Our results suggested that HY-PDT activated p38 MAPKs through the production of singlet oxygen. Inhibition of p38 MAPKs with chemical inhibitors or siRNA enhances HY-PDT-induced apoptosis of the HK-1 NPC cells.

Our previous studies have demonstrated the involvement of HIF-1 and p53 in the regulation of stanniocalcin-1 (STC1) gene transcription in human cancer cells. In this study, we reported that the treatment of human colon adenoma HT29 cells with a histone deacetylase (HDAC) inhibitor (i.e. trichostatin A, TSA) induced both cellular apoptosis and STC1 expression. The activation of STC1 expression was also observed in other TSA-treated human cancer cells (i.e. SKOV3, CaCo-2, Jurkat and CNE-2 cells). STC1 mRNA was rapidly induced within 4 h in TSA-treated HT29 cells, and was found to be transcriptionally regulated and was independent of new protein synthesis as revealed by ActD and CHX treatment respectively. The induction was correlated with increased cellular levels of acetyl histone H3 and H4 and acetyl NFkappaB. Chromatin immunoprecipitation (ChIP) assay showed the increased binding of acetyl histone H3 and H4 to STC1 promoter in the TSA-treated cells. A cotreatment of HT29 cells with a NFkappaB inhibitor (parthenolide) significantly inhibited the TSA-induced cellular levels of acetyl NFkappaB p65 and abolished the stimulation of STC1 gene expression. ChIP assay also demonstrated that TSA treatment increased while TSA/parthenolide cotreatment decreased NFkappaB p65 binding to STC1 gene promoter. In the STC1-luciferase promoter construct (1 kb) study, the data implied that the promoter can be activated by TSA treatment. Interestingly, the promoter region contains 2 putative NFkappaB binding sites. Consistent with the STC1mRNA expression data, TSA/parthenolide cotreatment also significantly inhibited the TSA-induced STC1 promoter-driven luciferase activity. Importantly, TSA-induced apoptotic process was found to be significantly reduced by the silencing of STC1 expression. This is the first study to show that histone hyper-acetylation and the recruitment of activated NFkappaB stimulated STC1 gene expression. In addition, our results support the notion that STC1 is a pro-apoptotic factor.

Benzo[a]pyrene (BaP) is a potentially genotoxic and cytotoxic environmental pollutant. Previous studies showed that exposure of HepG(2) cells to BaP causes necrotic cell death [Lin, T., Yang, M.S., 2007b. Cell death induced by benzo[a]pyrene in the HepG(2) cells is dependent on PARP-1 activation and NAD depletion. Toxicology 245, 147-153]. In the present study, the signaling pathways associated with this response was studied. BaP induced accumulation and activation of p53 in HepG(2) cells, which occurred as early as 12h after exposure. Activation of p53 was evidenced by its phosphorylation at serine 15 (Ser15) and acetylation at lysine 382 (Lys382). Chemical inhibition and siRNA-mediated knockdown of p53 expression suppressed its phosphorylation as well as cell death. BaP also activated p38 MAPK and ERK, but not JNK, at 6h after exposure. SB203580 and PD98059, specific inhibitors of p38 MAPK and ERK, respectively, suppressed phosphorylation of p53 at Ser15, but the accumulation of p53 was only moderately reduced. Acetylation of p53 at Lys 382 was not affected by these inhibitors, suggesting that acetylation stabilizes p53 in response to DNA damage. SB203580 and PD98059 prevented downstream energy failure and BaP-induced cell death. Similar results were obtained with siRNA against two isoforms of p38 MAPK, p38alpha and p38beta. Wortmannin, selective inhibitor of DNA-PK and ATM/ATR, abolished p53 phosphorylation, indicating an involvement of multiple pathways of p53 phosphorylation upon exposure to BaP. In summary, the current study demonstrated that both MAPK and p53 activation are required for BaP-induced necrotic cell death. The results also provide a novel model for studying the regulation between p53 and p38 MAPK in the progression of cellular necrosis.

Benzo[a]pyrene (BaP), a member of polycyclic aromatic hydrocarbons (PAH), has been reported to induce cell death in various cell types. However, the underlying mechanisms are controversial. In the present study, we report that BaP induces necrotic cell death in human hepatoma (HepG(2)) cells. The process is dependent on the activation of poly(ADP-ribose)polymerase-1 (PARP-1), a nuclear enzyme responsible for repairing DNA damage. Once activated, PARP-1 catalyzes the formation of ADP-ribose polymers on acceptor proteins at the expense of NAD(+). Incubation of cells with high extracellular concentration of NAD(+) (5mM) after BaP treatment caused an elevation in intracellular NAD(+) level and blocked cell death. Inhibitor of PARP-1 suppressed both overactivation of PARP-1 activity and NAD(+) depletion. Moreover, addition of pyruvate (5mM), but not glutamate (5mM) or glutamine (5mM), could restore ATP production and prevent cell death. These results elucidated a sequence of events linking cellular metabolism to the progression of cell death induced by this organic toxicant.

Astragalus memebranaceus is used as immunomodulating agent in treating immunodeficiency diseases and to alleviate the adverse effects of chemotherapeutic drugs. In recent years, it has been proposed that Astragalus may possess anti-tumorigenic potential in certain cancer cell types. In this study, the anti-carcinogenic effects of Astragalus saponin extract were investigated in HT-29 human colon cancer cells and tumor xenograft. Our findings have shown that Astragalus saponins (AST) inhibit cell proliferation through accumulation in S phase and G2/M arrest, with concomitant suppression of p21 expression and inhibition of cyclin-dependent kinase activity. Besides, AST promotes apoptosis in HT-29 cells through caspase 3 activation and poly(ADP-ribose) polymerase cleavage, which is indicated by DNA fragmentation and nuclear chromatin condensation. Nevertheless, we also demonstrate the anti-tumorigenic effects of AST in vivo, of which the reduction of tumor volume as well as pro-apoptotic and anti-proliferative effects in HT-29 nude mice xenograft are comparable with that produced by the conventional chemotherapeutic drug 5-fluorouracil (5-FU). In addition, the side effects (body weight drop and mortality) associated with the drug combo 5-FU and oxaliplatin are not induced by AST. These results indicate that AST could be an effective chemotherapeutic agent in colon cancer treatment, which might also be used as an adjuvant in combination with other orthodox chemotherapeutic drugs to reduce the side effects of the latter compounds.

There is growing evidence to suggest that altered patterns of STC1 gene expression relate to the process of human cancer development. Our previous study has demonstrated the involvement of HIF-1 in the regulation of STC1 expression in human cancer cells. Recently, STC1 has been implicated as a putative pro-apoptotic factor in regulating the cell-death mechanism. Thus it would be of interest to know if STC1 is regulated by a tumor suppressor protein, p53. In this study, we provide evidence to demonstrate that the induction of STC1 expression in apoptotic human nasopharyngeal cancer cells (CNE2) is mediated by the activation of p53. Our study indicated that the activation of STC1 and heat-shock protein (hsp70) accompanied iodoacetamide (IDAM)-induced apoptosis in CNE-2. In addition, cellular events such as GSH depletion, mitochondrial membrane depolarization, reduction of pAkt and procaspase-3, and the induction of total p53 protein, acetylated p53, and annexin V positive cells were observed. The activation of STC1 was found to be at the transcriptional level and was independent of prior protein synthesis. Co-treatment of IDAM exposed cells with N-acetyl cysteine (NAC) prevented cell death by restoring mitochondrial membrane potential and cellular levels of GSH. NAC co-treatment also suppressed STC1 expression but had no effect on IDAM-induced hsp70 expression. RNA interference studies demonstrated that endogenous p53 was involved in activating STC1 gene expression. Collectively, the present findings provide the first evidence of p53 regulation of STC1 expression in human cancer cells.

To investigate the mechanisms of the telomerase regulations during the apoptosis of the human MDS-RAEB cell line MUTZ-1 cells induced by arsenic trioxide (As(2)O(3)), telomerase activity was detected by TRAP-ELISA and the expressions of mRNAs of hTERT, TRF1 (TTAGGG repeat binding factor 1), TRF2 (TTAGGG repeat binding factor 2), bcl-2, and bax genes were detected by RT-PCR. Apoptosis was detected by translocation of phosphatidylserine (PS) by flow cytometry. The results showed that 1 - 8 micromol/L of As(2)O(3) induced typical apoptosis of MUIZ-1 cells in the dose-and time-dependent manners, the telomerase activity could be down-regulated at this concentration and negatively correlated with increased apoptosis (r = -0.938, P = 0.018). The expression of telomerase activity was positively related to the expression of hTERT (r = 0.783, P = 0.022), but As(2)O(3) had no effect on the mRNA expression of TRF1 and TRF2 genes. The inhibition of telomerase activity by As(2)O(3) on MUTZ-1 cells was accompanied with the low expression of bcl-2 gene and the decrease of bcl-2/bax ratio. It is concluded that the apoptosis of MUTZ-1cells induced by As(2)O(3) may occur via the inhibition of telomerase activity and down-regulation of the expression of hTERT mRNA, and this may be one of the mechanisms inducing apoptosis in MUTZ-1 cells treated by As(2)O(3).

Background/Aims: 2-O-methylmagnolol (MM1), a derivative of magnolol bearing one methoxy moiety, has been shown to display improved anti-tumor activity against skin cancers. In this study, we examined the anti-tumor effects of magnolol and MM1 on oral squamous cell carcinoma (OSCC). Methods: Trypane blue staining and clonogenic assays were performed to determine the cytotoxic effects of magnolol and MM1 in OSCC cells. Migration and matrigel invasion assays were carried out to examine the metastasis effects of magnolol and MM1 in OSCC cells. IL6-stimulation, Western blot, and immunohistochemistry were used to investigate the IL-6/STAT3 signaling and apoptosis. A bioluminescent mouse model of orthotopically implanted SAS cells was used to determine the anti-tumor activity of MM1 in vivo. Results: MM1 displays greater activity than magnolol on affecting the cytotoxicity, migration, and invasion of OSCC cells cultured in vitro. The improved anti-tumor activity of MM1 was shown to associate with its greater activity to inhibit STAT3 signaling and to induce apoptosis in the OSCC. In addition, we presented evidence that MM1 is effective in inhibiting the growth of orthotopic implanted OSCC cells in vivo. Conclusion: Our data indicate that MM1 displays greater anti-tumor activity than magnolol in OSCC and is an attractive agent to be further explored for its potential clinical application.

Patients with triple-negative breast cancer have few therapeutic strategy options. In this study, we investigated the effect of isoliquiritigenin (ISL) on the proliferation of triple-negative breast cancer cells. We found that treatment with ISL inhibited triple-negative breast cancer cell line (MDA-MB-231) cell growth and increased cytotoxicity. ISL reduced cell cycle progression through the reduction of cyclin D1 protein expression and increased the sub-G1 phase population. The ISL-induced apoptotic cell population was observed by flow cytometry analysis. The expression of Bcl-2 protein was reduced by ISL treatment, whereas the Bax protein level increased; subsequently, the downstream signaling molecules caspase-3 and poly ADP-ribose polymerase (PARP) were activated. Moreover, ISL reduced the expression of total and phosphorylated mammalian target of rapamycin (mTOR), ULK1, and cathepsin B, whereas the expression of autophagic-associated proteins p62, Beclin1, and LC3 was increased. The decreased cathepsin B cause the p62 accumulation to induce caspase-8 mediated apoptosis. In vivo studies further showed that preventive treatment with ISL could inhibit breast cancer growth and induce apoptotic and autophagic-mediated apoptosis cell death. Taken together, ISL exerts an effect on the inhibition of triple-negative MDA-MB-231 breast cancer cell growth through autophagy-mediated apoptosis. Therefore, future studies of ISL as a supplement or alternative therapeutic agent for clinical trials against breast cancer are warranted.

Epidermal growth factor receptor (EGFR) is frequently overexpressed and mutated in non-small cell lung cancer (NSCLC), which is the major type of lung cancer. The EGFR tyrosine kinase inhibitors (TKIs) are the approved treatment for patients harboring activating mutations in the EGFR kinase. However, most of the patients treated with EGFR-TKIs developed resistance. Therefore, the development of compounds exhibiting unique antitumor activities might help to improve the management of NSCLC patients. The total flavonoids from Daphne genkwa Sieb. et Zucc. have been shown to contain antitumor activity. Here, we have isolated a novel flavonoid hydroxygenkwanin (HGK) that displays selective cytotoxic effects on all of the NSCLC cells tested. In this study, we employed NSCLC cells harboring EGFR mutations and xenograft mouse model to examine the antitumor activity of HGK on TKI-resistant NSCLC cells. The results showed that HGK suppressed cancer cell viability both in vitro and in vivo. Whole-transcriptome analysis suggests that EGFR is a potential upstream regulator that is involved in the gene expression changes affected by HGK. In support of this analysis, we presented evidence that HGK reduced the level of EGFR and inhibited several EGFR-downstream signalings. These results suggest that the antitumor activity of HGK against TKI-resistant NSCLC cells acts by enhancing the degradation of EGFR.

The A/B subfamily of heterogeneous nuclear ribonucleoproteins (hnRNPs A/B), which includes hnRNP A1, A2/B1, and A3, plays an important role in cell proliferation. The simultaneous suppression of hnRNP A1/A2, but not the suppression of hnRNP A1 or A2 alone, has been shown to inhibit cell proliferation and induce apoptosis in cancer cells, but not in mortal normal cells. However, the molecular basis for such a differential inhibition of cell proliferation remains unknown. Here, we show that the simultaneous suppression of hnRNP A1 and hnRNP A2 resulted in dysfunctional telomeres and induced DNA damage responses in cancer cells. The inhibition of apoptosis did not alleviate the inhibition of cell proliferation nor the formation of dysfunctional telomeres in cancer cells depleted of hnRNP A1/A2. Moreover, while proliferation of mortal normal fibroblasts was not sensitive to the depletion of hnRNP A1/A2, the ectopic expression of hTERT in normal fibroblasts rendered these cells sensitive to proliferation inhibition, which was associated with the production of dysfunctional telomeres. Our study demonstrates that hnRNP A1 and A2 function to maintain telomeres in telomerase-expressing cells only, suggesting that the maintenance of functional telomeres in telomerase-expressing cancer cells employs factors that differ from those used in the telomerase-negative normal cells.

The extracts from Psoralea corylifolia Linn. (P. corylifolia) seeds have been shown to display antitumor activity. To date, the prospects of this plant and its active compounds in the treatment of non-small-cell lung cancer (NSCLC) have not been thoroughly studied. In this study, we identified a novel psorachromene compound that displays selective cytotoxic effects on all NSCLC cells tested, including NSCLC cells harboring epidermal growth factor receptor (EGFR) activation mutants (H1975L858R/T790M and H1975-MS35L858R/T790M/C797S ). Psorachromene induces G1 arrest in NSCLC cells harboring wild-type EGFR but induces apoptosis in NSCLC cells harboring activating EGFR mutations. Psorachromene inhibits activated EGFR signaling and kinase activity and suppresses tumor growth of implanted H1975-MS35L858R/T790M/C797S cells in nude mice. Molecular docking analysis revealed that psorachromene could form stronger bonds with mutant EGFR than wild-type EGFR, which might account for the greater cytotoxic effects observed in NSCLC cells harboring activating EGFR mutations (H1975 and H1975-MS35) than wild-type EGFR (A549). In conclusion, it is suggested that psorachromene is an attractive agent to be further explored for its use in the treatment of NSCLC patients harboring EGFR L858R/T790M/C797S. [ABSTRACT FROM AUTHOR]