Novel antitumor activities of Kushen flavonoids in vitro and in vivo

Kushen (KS), the dried roots of Sophora flavescens Aiton, has a long history of use in traditional Chinese medicine to treat inflammatory diseases and cancer. Kushen alkaloids (KS-As) and Kushen flavonoids (KS-Fs) are the well characterized components in KS. KS-As have been considered biologically active and developed in China as anticancer drugs. In an effort to screen novel antitumor agents from botanicals, more potent antitumor activities were identified in KS-Fs than in KS-As. KS-Fs were able to inhibit the growth of a panel of tumor cell lines and enhanced the antitumor activities of Taxol in vitro. The antitumor activities of KS-Fs and Kur, a single KS-Fs compound, were demonstrated in murine and xenograft human tumor models. Further, it was shown that KS-Fs and Kur were able to enhance the effect of Taxol to inhibit the growth of H460 and Eca-109 xenograft tumors. In addition, peripheral blood cell counts were not significantly affected in normal mice treated with KS-Fs at 200 mg/kg/day for 2 weeks. These results suggest that KS-Fs may be developed as novel antitumor agents and that the currently marketed KS-As drugs in China may have missed the major antitumor activities in Kushen.     

Apoptotic Effect of Galbanic Acid via Activation of Caspases and Inhibition of Mcl‐1 in H460 Non‐Small Lung Carcinoma Cells

Galbanic acid (GBA), a major compound of Ferula assafoetida, was known to have cytotoxic, anti‐angiogenic and apoptotic effects in prostate cancer and murine Lewis lung cancer cells; the underling apoptotic mechanism of GBA still remains unclear so far. Thus, in the present study, the apoptotic mechanism of GBA was investigated mainly in H460 non‐small cell lung carcinoma (NSCLC) cells because H460 cells were most susceptible to GBA than A549, PC‐9 and HCC827 NSCLC cells. Galbanic acid showed cytotoxicity in wild EGFR type H460 and A549 cells better than other mutant type PC‐9 and HCC827 NSCLC cells. Also, GBA significantly increased the number of Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) positive cells and sub G1 population in H460 cells. Western blotting revealed that GBA cleaved poly (ADP‐ribose) polymerase (PARP), activated Bax and caspase 9, attenuated the expression of Bcl‐2, Bcl‐x_L, and Myeloid cell leukemia 1 (Mcl‐1) in H460 cells. However, interestingly, overexpression of Mcl‐1 blocked the ability of GBA to exert cytotoxicity, activate caspase9 and Bax, cleave PARP, and increase sub G1 accumulation in H460 cells. Overall, these findings suggest that GBA induces apoptosis in H460 cells via caspase activation and Mcl‐1 inhibition in H460 cells as a potent anticancer agent for NSCLC treatment. Copyright © 2015 John Wiley & Sons, Ltd.     

c‐Jun N‐terminal Kinase‐Dependent Endoplasmic Reticulum Stress Pathway is Critically Involved in Arjunic Acid Induced Apoptosis in Non‐Small Cell Lung Cancer Cells

Though arjunic acid, a triterpene isolated from Terminalia arjuna, was known to have antioxidant, antiinflammatory, and cytotoxic effects, its underlying antitumor mechanism still remains unclear so far. Thus, in the present study, the molecular antitumor mechanism of arjunic acid was examined in A549 and H460 non‐small cell lung cancer (NSCLC) cells. Arjunic acid exerted cytotoxicity by 3‐[4, 5‐dimethylthiazol‐2‐yl]‐2, 5‐diphenyl tetrazolium bromide (MTT) assay and significantly increased sub‐G1 population in A549 and H460 cells by cell cycle analysis. Consistently, arjunic acid cleaved poly (ADP‐ribose) polymerase (PARP), activated Bax, and phosphorylation of c‐Jun N‐terminal kinases (JNK), and also attenuated the expression of pro‐caspase‐3 and Bcl‐2 in A549 and H460 cells. Furthermore, arjunic acid upregulated the expression of endoplasmic reticulum (ER) stress proteins such as IRE1 α, ATF4, p‐eIF2α, and C/EBP homologous protein (CHOP) in A549 and H460 cells. Conversely, CHOP depletion attenuated the increase of sub‐G1 population by arjunic acid, and also JNK inhibitor SP600125 blocked the cytotoxicity and upregulation of IRE1 α and CHOP induced by arjunic acid in A549 and H460 cells. Overall, our findings suggest that arjunic acid induces apoptosis in NSCLC cells via JNK mediated ER stress pathway as a potent chemotherapeutic agent for NSCLC.     

Curcumin inhibits human lung large cell carcinoma cancer tumour growth in a murine xenograft model

Curcumin can decrease viable cells through the induction of apoptosis in human lung cancer NCI‐H460 cells in vitro. However, there are no reports that curcumin can inhibit cancer cells in vivo. In this study, NCI‐H460 lung tumour cells were implanted directly into nude mice and divided randomly into four groups to be treated with vehicle, curcumin (30 mg/kg of body weight), curcumin (45 mg/kg of body weight) and doxorubicin (8 mg/kg of body weight). Each agent was injected once every 4 days intraperitoneally (i.p.), with treatment starting 4 weeks after inoculation with the NCI‐H460 cells. Treatment with 30 mg/kg and 45 mg/kg of curcumin or with 8 mg/kg of doxorubicin resulted in a reduction in tumour incidence, size and weight compared with the control group. The findings indicate that curcumin can inhibit tumour growth in a NCI‐H460 xenograft animal model in vivo. Copyright © 2010 John Wiley & Sons, Ltd.     

新型4-苯胺基喹唑啉类酪氨酸激酶抑制剂的抗肿瘤活性研究

目的对合成的新型4-苯胺基喹唑啉类酪氨酸激酶抑制剂TYIG1~TYIG9进行抗肿瘤活性研究,为寻找具有靶向抗肿瘤活性的候选化合物提供依据。方法采用均相时间分辨荧光（HTRF）法对化合物进行EGFR、VEGFR-2两个靶点的体外活性筛选;采用MTS法对化合物进行肿瘤细胞（A431、A549、H1975、MDA-MB-231）增殖抑制的体外活性评价;采用人肺癌H1975细胞的移植瘤裸鼠模型评价其在动物体内抗肿瘤活性。结果采用HTRF法从合成的一系列化合物中筛选出化合物TYIG4~TYIG9对EGFR、VEGFR-2激酶的活性较好。MTS法检测得到这6个化合物对4种肿瘤细胞（A431、A549、H1975、MDA-MB-231）均有不同程度的抑制作用,其中TYIG6的增殖抑制作用的选择性更为突出;体内试验结果表明TYIG6能够剂量相关性地抑制肿瘤生长,50、100 mg/kg TYIG6对H1975的相对肿瘤抑制率分别为42.59%、34.92%。结论 TYIG6具有良好的体内外抗肿瘤活性,具有成为新型双靶点酪氨酸激酶抑制剂的潜能,有进一步的研究价值。     

Growth inhibition and induction of apoptosis in human oral squamous cell carcinoma Tca-8113 cell lines by Shikonin was partly through the inactivation of NF-kappaB pathway

Shikonin, a naphthoquinone pigment isolated from the Chinese herbal therapeutic, Zicao, has been shown to exhibit antioxidant and anticancer effects. In this study, its ability to induce apoptosis in cultured Tca-8113 oral cancer cells was studied. Treatment of the Tca-8113 cells with a variety of concentrations of Shikonin (10-40 microm) resulted in dose- and time-dependent sequences of events marked by apoptosis, as shown by the loss of cell viability, chromatin condensation, internucleosomal DNA fragmentation and sub-G1 phase accumulation. Furthermore, apoptosis in the Tca-8113 cells was accompanied by the activation of protease caspase-8, -9, -3 and low expression of Bcl-2 protein. Interestingly, inactivation of the NF-kappaB pathway was found in shikonin-induced apoptosis in Tca-8113 cells. These results raise the possibility that the anti-tumor effects of Shikonin in Tca-8113 cells are at least partly through the inactivation of the NF-kappaB pathway and subsequent activation of protease caspase family. Pharmacological inhibition of the NF-kappaB activity by Shikonin might be a powerful treatment option for OSCC in which activation of NF-kappaB plays a critical role in tumor growth and progression.     

Curcumin Reactivates Silenced Tumor Suppressor Gene RARβ by Reducing DNA Methylation

Reactivation of tumor suppressor genes by nontoxic bioactive food component represents a promising strategy for cancer chemoprevention. Retinoic acid receptor β (RARβ), one member of the RAR receptor family, is considered as a tumor suppressor. Reduced expression of RARβ has been reported in lung cancer and other solid tumors. DNA hypermethylation of the promoter region of RARβ is a major mechanism for its silencing in tumors. Recently, curcumin has been considered as a potential DNA methyltransferase inhibitor. Herein, we demonstrated that curcumin significantly elevate RARβ expression at the mRNA and protein levels in tested cancer cells. Additionally, curcumin decreased RARβ promoter methylation in lung cancer A549 and H460 cells. Mechanistic study demonstrated that curcumin was able to downregulate the mRNA levels of DNMT3b. In a lung cancer xenograft node mice model, curcumin exhibited protective effect against weight loss because of tumor burden. Tumor growth was strongly repressed by curcumin treatment. As the results from in vitro, RARβ mRNA were increased and DNMT3b mRNA were decreased by curcumin treatment compared with the mice in control group. Altogether, this study reveals a novel molecular mechanism of curcumin as a chemo‐preventive agent for lung cancer through reactivation of RARβ. Copyright © 2015 John Wiley & Sons, Ltd.     

Mangosenone F,A Furanoxanthone from Garciana mangostana,Induces Reactive Oxygen Species‐Mediated Apoptosis in Lung Cancer Cells and Decreases Xenograft Tumor Growth

Mangosenone F (MSF), a natural xanthone, was isolated form Carcinia mangotana, and a few studies have reported its glycosidase inhibitor effect. In this study we investigated the anti lung cancer effect of MSF both in vitro and in vivo. MSF inhibited cancer cell cytotoxicity and induced and induced apoptosis via reactive oxygen species (ROS) generation in NCI‐H460. MSF treatment also showed in pronounced release of apoptogenic cytochrome c from the mitochondria to the cytosol, downregulation of Bcl‐2 and Bcl‐xL, and upregulation of Bax, suggesting that caspase‐mediated pathways were involved in MSF‐induced apoptosis. ROS activation of the mitogen‐activated protein kinase signaling pathway was shown to play a predominant role in the apoptosis mechanism of MSF. Compared with cisplatin treatment, MSF treatment showed significantly increased inhibition of the growth of NCI‐H460 cells xenografted in nude mice. Together, these results indicate the potential of MSF as a candidate natural anticancer drug by promoting ROS production. Copyright © 2015 John Wiley & Sons, Ltd.     

Apigenin as an anticancer agent

Apigenin is an edible plant‐derived flavonoid that has been reported as an anticancer agent in several experimental and biological studies. It exhibits cell growth arrest and apoptosis in different types of tumors such as breast, lung, liver, skin, blood, colon, prostate, pancreatic, cervical, oral, and stomach, by modulating several signaling pathways. Apigenin induces apoptosis by the activation of extrinsic caspase‐dependent pathway by upregulating the mRNA expressions of caspase‐3, caspase‐8, and TNF‐α. It induces intrinsic apoptosis pathway as evidenced by the induction of cytochrome c, Bax, and caspase‐3, while caspase‐8, TNF‐α, and B‐cell lymphoma 2 levels remained unchanged in human prostate cancer PC‐3 cells. Apigenin treatment leads to significant downregulation of matrix metallopeptidases‐2, ?9, Snail, and Slug, suppressing invasion. The expressions of NF‐κB p105/p50, PI3K, Akt, and the phosphorylation of p‐Akt decreases after treatment with apigenin. However, apigenin‐mediated treatment significantly reduces pluripotency marker Oct3/4 protein expression which might be associated with the downregulation of PI3K/Akt/NF‐κB signaling.     

Daikenchuto (TU‐100) Suppresses Tumor Development in the Azoxymethane and APCmin/+ Mouse Models of Experimental Colon Cancer

Chemopreventative properties of traditional medicines and underlying mechanisms of action are incompletely investigated. This study demonstrates that dietary daikenchuto (TU‐100), comprised of ginger, ginseng, and Japanese pepper effectively suppresses intestinal tumor development and progression in the azoxymethane (AOM) and APC^min/+ mouse models. For the AOM model, TU‐100 was provided after the first of six biweekly AOM injections. Mice were sacrificed at 30 weeks. APC^min/+ mice were fed diet without or with TU‐100 starting at 6 weeks, and sacrificed at 24 weeks. In both models, dietary TU‐100 decreased tumor size. In APC ^min/+ mice, the number of small intestinal tumors was significantly decreased. In the AOM model, both TU‐100 and Japanese ginseng decreased colon tumor numbers. Decreased Ki‐67 and β‐catenin immunostaining and activation of numerous transduction pathways involved in tumor initiation and progression were observed. EGF receptor expression and stimulation/phosphorylation in vitro were investigated in C2BBe1 cells. TU‐100, ginger, and 6‐gingerol suppressed EGF receptor induced Akt activation. TU‐100 and ginseng and to a lesser extent ginger or 6‐gingerol inhibited EGF ERK1/2 activation. TU‐100 and some of its components and metabolites of these components inhibit tumor progression in two mouse models of colon cancer by blocking downstream pathways of EGF receptor activation. Copyright © 2016 John Wiley & Sons, Ltd.     

两种真菌多糖对HL-60细胞酪氨酸蛋白磷酸化作用的影响

 目的：研究猪苓多糖和茯苓多糖对人早幼粒白血病细胞(HL-60)酪氨酸蛋白磷酸化作用的影响。方法：用一定浓度的药物处理体外培养的HL60细胞。用放射免疫法测定经过培养12,24,48,72和120 h对照组和药物处理组细胞浆和膜部分的酪氨酸蛋白激酶(TPK)和磷酸酪氨酸蛋白磷酸酶(PTPP)的活力,比较酶活力变化情况。结果：两种多糖对胞浆和膜部分TPK活力均有不同程度的抑制作用。而对两部分PTPP的活力均有不同程度的激活作用。结论：两种真菌多糖均可使HL-60细胞酪氨酸蛋白磷酸化水平下降,提示两种多糖杭肿瘤作用的机制可能与酪氨酸蛋白磷酸化作用有关。     

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??OBJECTIVE To study the anti-leukemia activities and mechanisms of bergenin derivative D-23. METHODS CCK-8 method was applied to investigate anti-tumor activities of D-23. Flow cytometry and immunofluorescence assay were used to observe the effects of D-23 on the apoptosis and autophagy in K562 and Jurkat human leukemia cell lines. Western blot analysis was used to investigate the mechanisms that compound D-23 induced tumor cell apoptosis and autophagy. RESULTS Bergenin derivative D-23 could significantly inhibit the proliferation of K562 and Jurkat cells by inducing cell apoptosis and autophagy. The mitochondrial membrane potential was decreased,protein kinase B(Akt)and heat shock protein 70 (Hsp70) were inhibited,and the expressions of apoptotic related proteins caspase 3 and caspase 9 were activated. In addition, mammalian target of rapamycin (P-mTOR)(Ser 2448 and Ser 2481)protein was inhibited. CONCLUSION Bergenin derivative D-23 shows obvious anti-leukemia activities by inducing cell apoptosis and autophagy. The apoptosis may be associated with the reduction of mitochondrial membrane potential and activation of caspase pathway. The autophagy may be related to the inhibition of Akt/mTOR signaling pathway.     

The anti-inflammatory effects of Pyrolae herba extract through the inhibition of the expression of inducible nitric oxide synthase (iNOS) and NO production

The extract of Pyrolae herba (PH), which has been used as an anti-inflammatory folk remedy in Korea and China, was investigated for its anti-inflammatory action using arachidonic acid, 12-O-tetradecanoylphorbol 13-acetate or carrageenan-induced edema assays. The anti-nociceptive activity of PH was also tested in mice using the acetic acid-induced writhing model. PH showed dose-dependent and significant (P<0.05 at 100-400mg/kg) anti-inflammatory and anti-nociceptive activities in the animal assays. The mechanism of the activities of PH was examined by testing the extract to determine if it inhibits the expression of inducible nitric oxide synthase (iNOS) and the production of nitric oxide (NO) from the murine macrophages, RAW 264.7 cells. Similar to the in vivo activities, both the iNOS expression and NO production were significantly suppressed by PH in a dose-dependent manner. PH also inhibited the activating phosphorylation of p38 MAP kinase and NF-kappaB in these cells. These results provide a scientific basis to explain the effects of PH as an anti-inflammatory folk remedy in Asian countries.     

Obovatol Induces Apoptosis in Non‐small Cell Lung Cancer Cells via C/EBP Homologous Protein Activation

Although obovatol, a phenolic compound from the bark of Magnolia obovata, was known to have antioxidant, neuroprotective, antiinflammatory, antithrombotic and antitumour effects, its underlying antitumour mechanism is poorly understood so far. Thus, in the present study, the antitumour molecular mechanism of obovatol was investigated in non‐small cell lung cancer cells (NSCLCs). Obovatol exerted cytotoxicity in A549 and H460 NSCLCs, but not in BEAS‐2B cells. Also, obovatol increased sub‐G1 accumulation and early and late apoptotic portion in A549 and H460 NSCLCs. Consistently, obovatol cleaved PARP, activated caspase 9/3 and Bax and attenuated the expression of cyclin D1 in A549 and H460 NSCLCs. Interestingly, obovatol upregulated the expression of endoplasmic reticulum stress proteins such as C/EBP homologous protein (CHOP), IRE1α, ATF4 and p‐elF2 in A549 and H460 NSCLCs. Conversely, depletion of CHOP blocked the apoptotic activity of obovatol to increase sub‐G1 accumulation in A549 and H460 NSCLCs. Overall, our findings support scientific evidences that obovatol induces apoptosis via CHOP activation in A549 and H460 NSCLCs. Copyright © 2016 John Wiley & Sons, Ltd.     

Antitumor activity of bruceantin: an old drug with new promise

Bruceantin was first isolated from Brucea antidysenterica, a tree used in Ethiopia for the treatment of cancer, and activity was observed against B16 melanoma, colon 38, and L1210 and P388 leukemia in mice. Phase I and II clinical trials were then initiated, but no objective tumor regressions were observed and clinical development was terminated. Recently, the activity of bruceantin has been studied with a number of leukemia, lymphoma, and myeloma cell lines. Cell differentiation was induced and c-MYC was down-regulated, suggesting a mechanistic correlation between c-MYC down-regulation and induction of cell differentiation or cell death. Treatment of HL-60 and RPMI 8226 cell lines induced apoptosis, and this involved the caspase and mitochondrial pathways. Moreover, an in vivo study using RPMI 8226 human-SCID xenografts demonstrated that bruceantin induced regression in early as well as advanced tumors, and these significant antitumor responses were facilitated in the absence of overt toxicity. Apoptosis was significantly elevated in tumors derived from animals treated with bruceantin. In sum, bruceantin interferes with the growth of leukemia, lymphoma, and myeloma cells in culture and xenograft models. Responses of this type suggest bruceantin should be reinvestigated for clinical efficacy against hematological malignancies.     

Effect of Orostachys japonicus on cell growth and apoptosis in human hepatic stellate cell line LX2

Orostachys japonicus (O. japonicus), used to treat diseases such as various cancers, gastric ulcers, fever, hepatitis, arthritis, eczema, for hemostasis, and intoxication in folk medicine, has been an important constituent in many herbal formulae. We demonstrated that the water extract of O. japonicus led to growth inhibition of LX2 cells by inducing apoptosis through the caspase activation, related to the MAPK pathway. O. japonicus inhibited proliferation of LX2 cells in a dose- and time-dependent manner, increased the apoptosis fraction at cell cycle progression with an accompanying DNA fragmentation, and resulted in a significant decrease in Bcl-2 and an increase in Bax mRNA levels. Exposure of LX2 cells to O. japonicus induced caspase-3 activation, however when the LX2 cells were also treated with the pan-caspase inhibitor Z-VAD-FMK and the caspase-3 inhibitor Z-DEVE-FMK, apoptosis was blocked. O. japonicus inhibited anti-apoptotic Mcl-1 protein and MEK/ERK phosphorylation in LX2 cells. The results indicate that O. japonicus inhibits the cell growth of LX2 cells by inducing apoptosis through caspase activity. O. japonicus down-regulated Mcl-1 protein levels and inhibited the phosphorylation of MEK/ERK, suggesting that it mediates cell death in LX2 cells through the down-regulation of Mcl-1 protein via a MEK/ERK-independent pathway.     

去甲斑蝥素抑制人骨肉瘤U2OS细胞生长及其机制研究

目的：探讨去甲斑蝥素抑制人骨肉瘤U2OS细胞生长的作用及其分子机制,为开发抗骨肉瘤新药提供实验基础。方法：以不同浓度的去甲斑蝥素处理骨肉瘤U2OS细胞,应用MTT法检测细胞生长抑制率,用Bliss法计算IC50值,通过流式细胞术和Hoechst33258荧光染色检测细胞凋亡,Caspase-3、8、9活性检测试剂盒检测其活性。结果：5、10、20、40、80μg/mL的去甲斑蝥素明显抑制骨肉瘤U2OS细胞生长并呈剂量依赖关系,48h的IC50值为26.15μg/mL;20μg/mL去甲斑蝥素作用12、24、48h诱导U2OS细胞的凋亡率分别为：7.8%、26.3%和43.9%,并出现明显的凋亡特征性形态变化;去甲斑蝥素处理U2OS细胞48h后Caspase-3、8、9的活性明显增强。结论：去甲斑蝥素可通过激活Caspase级联活化而抑制骨肉瘤U2OS细胞生长并诱导凋亡。     

Anti‐lung Cancer Effects of Polyphyllin VI and VII Potentially Correlate with Apoptosis In Vitro and In Vivo

Polyphyllin VI (PVI) and polyphyllin VII (PVII) derived from Paris polyphylla possess anti‐cancer activities. However, the mechanisms for the anti‐lung cancer effects of PVI and PVII remain poorly understood. In this study, PVI and PVII exhibited inhibitory effects on the proliferation of A549 and NCI‐H1299 cells. PVI and PVII induced G2/M cell cycle arrest and triggered apoptosis. PVI and PVII upregulated the tumor suppressor protein p53 and downregulated cyclin B1. The two treatments significantly increased the expression levels of death receptor 3, death receptor 5, Fas, cleaved PARP, and cleaved caspase‐3. Furthermore, PVI and PVII significantly inhibited the growth of A549 cells in vivo. The tumor inhibitory rates of PVI were 25.74%, 34.62%, and 40.43% at 2, 3, and 4 mg/kg, respectively, and those of PVII were 25.63%, 41.71%, and 40.41% at 1, 2, and 3 mg/kg, respectively. Finally, PVI and PVII regulated the expression of proteins related to the apoptotic pathway in A549 xenografts. In summary, PVI and PVII exhibited strong inhibitory effects on lung cancer cell growth in vitro and in vivo by inducing G2/M cell cycle arrest and triggering apoptosis. Copyright © 2015 John Wiley & Sons, Ltd.     

Activation of AMP‐activated Protein Kinase and Phosphorylation of Glycogen Synthase Kinase3 β Mediate Ursolic Acid Induced Apoptosis in HepG2 Liver Cancer Cells

Despite the antitumour effect of ursolic acid observed in several cancers, the underlying mechanism remains unclear. Thus, in the present study, the roles of AMP‐activated protein kinase (AMPK) and glycogen synthase kinase 3 beta (GSK3β) were examined in ursolic acid induced apoptosis in HepG2 hepatocellular carcinoma cells. Ursolic acid significantly exerted cytotoxicity, increased the sub‐G1 population and the number of ethidium homodimer and terminal deoxynucleotidyl transferase(TdT) mediated dUTP nick end labeling positive cells in HepG2 cells. Also, ursolic acid enhanced the cleavages of poly‐ADP‐ribose polymerase (PARP) and caspase3, attenuated the expression of astrocyte elevated gene (AEG1) and survivin in HepG2 cells. Interestingly, ursolic acid increased the phosphorylation of AMPK and coenzyme A carboxylase and also enhanced phosphorylation of GSK3β at inactive form serine 9, whereas ursolic acid attenuated the phosphorylation of AKT and mTOR in HepG2 cells. Conversely, AMPK inhibitor compound C or GSK3β inhibitor SB216763 blocked the cleavages of PARP and caspase 3 induced by ursolic acid in HepG2 cells. Furthermore, proteosomal inhibitor MG132 suppressed AMPK activation, GSK3β phosphorylation, cleaved PARP and deceased AEG‐1 induced by ursolic acid in HepG2 cells. Overall, our findings suggest that ursolic acid induced apoptosis in HepG2 cells via AMPK activation and GSK3β phosphorylation as a potent chemopreventive agent. Copyright © 2013 John Wiley & Sons, Ltd.     

Dual inhibition of EGFR and MET by Echinatin retards cell growth and induces apoptosis of lung cancer cells sensitive or resistant to gefitinib

Patients with non‐small‐cell lung cancer (NSCLC) containing epidermal growth factor receptor (EGFR) amplification or sensitive mutations initially respond to tyrosine kinase inhibitor gefitinib; however, the treatment is less effective over time. Gefitinib resistance mechanisms include MET gene amplification. A therapeutic strategy targeting MET as well as EGFR can overcome resistance to gefitinib. In the present study we identified Echinatin (Ecn), a characteristic chalcone in licorice, which inhibited both EGFR and MET and strongly altered NSCLC cell growth. The antitumor efficacy of Ecn against gefitinib‐sensitive or –resistant NSCLC cells with EGFR mutations and MET amplification was confirmed by suppressing cell proliferation and anchorage‐independent colony growth. During the targeting of EGFR and MET, Ecn significantly blocked the kinase activity, which was validated with competitive ATP binding. Inhibition of EGFR and MET by Ecn decreases the phosphorylation of downstream target proteins ERBB3, AKT and ERK compared with total protein expression or control. Ecn induced the G2/M cell cycle arrest, and apoptosis via the intrinsic pathway of caspase‐dependent activation. Ecn induced ROS production and GRP78, CHOP, DR5 and DR4 expression as well as depolarized the mitochondria membrane potential. Therefore, our results suggest that Ecn is a promising therapeutic agent in NSCLC therapy.