This article has Open Peer Review reports available.
Guibitang, a traditional herbal medicine, induces apoptotic death in A431 cells by regulating the activities of mitogen-activated protein kinases
© Yim et al.; licensee BioMed Central Ltd. 2014
Received: 22 April 2014
Accepted: 16 September 2014
Published: 21 September 2014
Guibi-tang (GBT), a traditional herbal formula, mainly has been shown to possess immune regulation, antioxidant and protective effect of the gastric mucosa. Constituent herbs of GBT are frequently used to treat various diseases; however, their pharmacological effects, especially on cancer cells, differ from those of GBT. Furthermore, the molecular mechanisms behind effects of GBT remain unclear. In the present study, we explored the mechanism of chemopreventive/chemotherapeutic efficacy of GBT against human squamous cell carcinoma without cytotoxicity in normal cells and proved the efficacy of GBT through performing in vivo xenograft assay.
For analysis of the constituents of GBT, high performance liquid chromatography (HPLC)-DAD system was performed. To detect the anticancer effect of GBT, cell viability assay, caspase activity assay, cell cycle analysis, DNA fragmentation analysis, and Western blot analysis were performed in A431 cells. In addition, the inhibitory effect of tumor growth by GBT was evaluated in athymic nude mice inoculated with A431 cells.
GBT showed cytotoxic activity against three different squamous cell carcinoma, especially on A431 cells. GBT induced the apoptosis through activating the caspase-8 in A431 cells. Inhibition of A431 cell growth by GBT was caused by G1-phase arrest through regulating proteins associated with cell cycle progression, such as cyclin D1, p21, and p27. Furthermore, GBT regulated the activation of mitogen-activated protein kinases (MAPKs) including extracellular signal-regulated kinase (ERK), p38 and c-Jun NH2-terminal kinase (JNK), and activated p53, a tumor suppressor protein. In MAPKs inhibitor study, inhibitors respectively blocked GBT-induced cell viability, indicating that MAPKs signals play critical role in cell death caused by GBT. In vivo xenografts, daily oral administration of 600 mg/kg GBT efficiently suppressed the tumorigenic growth of A431 cells without side effects such as loss of body weight and change of toxicological parameters compared to vehicle.
We first elucidate that GBT stimulates the apoptotic signaling pathway and suppresses the proliferation of A431 cells via regulating MAPKs signaling pathway. Furthermore, GBT significantly inhibits tumor growth of A431 cells without causing systemic toxicity. Based on our study, GBT could be useful in the management of skin cancer as chemoprevention and chemotherapy remedy.
Basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) are commonly referred to as non-melanoma skin cancers[1, 2]. BCC is a slow-growing cancer that does not usually metastasize. Similarly, SCC is frequently localized without evidence of blood-born metastasis, making direct treatment of the tumor straightforward. However, SCC is the sixth most common cancer worldwide, and its incidence has increased dramatically at multiple sites in the body, including the head and neck, cervix, and lung[3, 4]. Accordingly, it is necessary to develop novel effective chemopreventive agents to inhibit the development of SCC.
Guibitang (GBT), known as ‘Kihi-to’ in Japan and ‘Gui-Pi-Tang’ in China, is a traditional medicine and herbal formula that has been used for several hundred years, predominantly to treat insomnia, amnesia, palpitations, anxiety, fatigue, poor appetite, and depression. Recent studies have reported the specific bioactivities of GBT, which include immune regulation, antioxidant effects, and protective effect of the gastric mucosa. GBT is an aqueous polyherbal formulation that contains 12 herbs: Angelica gigas Nakai, Dimocarpus longan, Zizyphus jujuba Miller (seed), Polygala tenuifolia, Panax ginseng, Astragalus membranaceus, Atractylodes ovate, Poria cocos, Inula helenium, Glycyrrhiza glabra, Zingiber officinale, and Zizyphus jujuba Miller (Fructus). GBT also regulates chronic fatigue syndrome-associated cytokine production, whereas the addition of Gardenia jasminoides, Paeonia suffruticosa, and Bupleurum falcatum to GBT improves palliative care in patients undergoing chemotherapy for ovarian cancer. Although it has been shown that adding several herbs to GBT results in anti-cancer effects against gynecological or lung cancer, the molecular mechanisms behind these effect of GBT remain unclear. Tumorigenesis is caused by unregulated growth of cells resulting from DNA damage, mutations of functional genes, dysregulation of the cell cycle, and loss of apoptotic function. Therefore, regulating the induction of apoptosis by modulating cell growth and survival-related signaling pathways is a common and major target for cancer therapies. Among several signaling pathways in cancer cells, mitogen-activated protein kinase (MAPK) signals including extracellular signal-regulated kinases (ERK), p38 kinases, and c-Jun N-terminal kinases (JNK), take an important role in cell death and survival. The regulation of ERK activation is induced by conditions of stress such as some agents and oxidant injury, which plays a major role in regulating cell growth and differentiation. JNK and p38 are activated in response to several stress signals including tumor necrosis factor and hyperosmotic condition, which is associated with induction of apoptosis. In the present study, we evaluated whether GBT shows the anti-cancer effect in A431 human squamous carcinoma cells, which demonstrated that GBT induces apoptosis of cancer cells specifically, as an inhibition of the cell growth via regulating MAPK signaling pathway in A431 cells.
Various human cancer cell lines, obtained from the Korean Cell Line Bank (KCLB, Seoul, Korea) and American Type Culture Collection (ATCC, Rockville, MD), were cultured in Dulbecco’s modified Eagle’s medium (DMEM) and RPMI-1640 (Lonza, Walkersville, MD) supplemented with 10% fetal bovine serum (FBS; Hyclone, Logan, UT). Primary hepatic cells obtained from mice were grown in Williams E Medium (GIBCO, Gaithersburg, MD) supplemented with 10% FBS. All media contained 100 U/mL penicillin G and 100 μg/mL streptomycin (GIBCO). Cells were incubated in a humidified 5% CO2 atmosphere at 37°C.
Herb materials and preparation of GBT
Composition of the Guibitang (GBT) preparation
Amount used (g)
Angelica gigas Nakai
Zizyphus jujuba Miller
Zingiber officinale Rosc.
Inula helenium L.
Zizyphus jujuba Miller
Glycyrrhiza glabra Fisch
Characterization of standard compounds in GBT by HPLC
Decursin + Decursinol angelate
Cell viability assay
Cells (4 × 103 or 5 × 103 per well) were inoculated in a 96-well plate and treated with GBT for 24 or 48 h. After incubation, cell viability was analyzed by 3-[4, 5-dimethylthiazol-2-ly]-2, 5-diphenyl-tetrazolium bromide (MTT) assay as described previously. For growth analysis, cells were seeded at a density of 1 × 105/mL and treated with GBT for 1, 2, or 3 days. The cells were counted and the doubling time was calculated using an online tool (http://www.doubling-time.com/compute.php).
Cell cycle analysis
Cells were seeded at a density of 1 × 105/mL and treated with GBT for 12 or 24 h. The propidium iodide (PI; Sigma-Aldrich, St. Louis, MO) staining for cell cycle analysis were performed as described previously. DNA contents of the stained cells were analyzed by FACS Calibur flow cytometry using Cell Quest software (Becton–Dickinson, Franklin Lakes, NJ).
Caspase activity assay
To determine caspase-3/7 activity, cells were seeded at a density of 1 × 104/well in a 96-well plate and treated with GBT for 24 h. Caspase activity was measured in triplicate by using a Caspase-Glo 3/7 assay kit (Promega, Madison, WI) according to the manufacturer’s instructions. Culture medium was used as a blank control and luminescence was measured using an MLX microtiter luminometer (Dynex Technologies Inc., Chantilly, VA).
DNA fragmentation analysis
To investigate the apoptotic effect of GBT, we assessed oligonucleosomal DNA fragmentation by agarose gel electrophoresis. Cells were harvested at 12 and 24 h after treatment. Genomic DNA was prepared from harvested cells using a Genomic DNA Purification Kit (Promega, Madison, WI) according to the manufacturer’s instructions. It was then subjected to electrophoresis on a 1.5% agarose gel impregnated with ethidium bromide reagent (Sigma-Aldrich, St. Louis, MO) to detect ladder formation.
Western blot analysis
The cell lysates treated with GBT for western blot analysis were prepared as described previously. The same amount of protein for each sample was electrophoresed and transferred onto a polyvinylidene difluoride (PVDF) membrane (Millipore, Billerica, MA). Proteins were detected using primary antibodies specific for cyclin D1, cyclin B1, p21, p27, caspase-3, caspase-8, caspase-9, Bid, Bax, Bcl-2, PARP, ERK, phospho-ERK, p38, phospho-p38, JNK, phospho-JNK, p53, GAPDH, and β-actin, all of which were obtained from Cell Signal Technology. This was followed by incubation with HRP-conjugated secondary antibodies for 1 h at room temperature. The specific protein was detected using the enhanced chemiluminescence imaging system (CoreBio, Seoul, Korea).
Animals and tumor xenografts
Female mice (Athymic nu/nu, 8 weeks, 25–29 g; NARA Bio, Seoul, Korea) were acclimated under conditions of constant temperature (24 ± 1°C) and humidity (55 ± 15%) with 12 h light/dark cycle for 1 week. Mice were injected subcutaneously with 3 × 106 A431 cells/100 μL harvested and suspended in DMEM medium without FBS. Mice with palpable tumors were divided into two groups for study, and group 1 (vehicle, n=5) mice received the injection of physiological saline (Choongwae Normal Saline Inj., Korea), whereas group 2 (GBT, n=5) orally received GBT. The administrated amount of GBT for human adults with an average body weight of 60 Kg is approximately 12~36 g/day and the yield of powdered extraction is approximately 30% (wt/wt). Based on this estimation data, GBT at the doses of 600 mg/day/Kg of body weight was orally administered to mice for 14 days. GBT treatment was started at day 3 following the tumor cell inoculation. Tumor volume was monitored using electronic caliper on every alternate day and tumor volume was calculated using following formula: tumor volume = length × width × width/2. The experiment was terminated at the end of 15 days when the vehicle-treated animals had large tumors, which was sacrified by obtaining blood from abdominal vein. For determining the toxicity of GBT, chemical analysis of serums obtained from mice was determined using an Auto Biochemistry Analyzer (XL-200, Erba Diagnostics, Mannheim, Germany) and complete blood cell count (CBC) from mice was analyzed using a ADVIA 2120i Hematology System (Siemens Healthcare, Camberley, UK). The animal experimental procedures were approved by Korea Institute of Oriental Medicine Care and Use Committee with a reference number of #12-094 and #13-030, and performed in accordance with the Korea Institute of Oriental Medicine Care Committee Guide lines.
Data are presented as means ± SD. Student’s t-test was employed to assess the statistical significance of differences between the control and GBT-treated groups. Values of p <0.05 and <0.01 were considered to indicate statistical significance.
GBT decreases cell viability in A431 human squamous carcinoma cells
GBT causes cell cycle arrest in G1 and increases the sub-G1 population in A431 cells
GBT-stimulated activation of pro-apoptotic proteins and DNA fragmentation is attributable to the induction of apoptosis in A431 cells
GBT regulates the phosphorylation of cell proliferation-related proteins including MAPK cascades and p53 in A431 cells
GBT administration inhibits tumorigenic growth of A431 cells in vivo
Chemical analysis of serums obtained from mice administrated with 600 mg/Kg of GBT
54.0 ± 3.5
28 ± 0.0
48.0 ± 22.3
420.0 ± 65.8
27.9 ± 7.6
1.0 ± 0.0
41.3 ± 4.6
26 ± 0.0
30.7 ± 21.9
319.3 ± 94.7
27.5 ± 0.2
1.0 ± 0.0
Hematological analysis of bloods obtained from mice administrated with 600 mg/Kg of GBT
WBCP (x103 cells/μL)
4.48 ± 1.22
4.02 ± 1.19
WBCB (x103 cells/μL)
4.53 ± 1.15
4.10 ± 1.24
RBC (x106 cells/μL)
8.74 ± 0.26
8.99 ± 0.48
Means HGB (g/dL)
13.8 ± 0.06
14.0 ± 1.11
47.8 ± 1.40
49.1 ± 1.81
54.7 ± 0.40
54.6 ± 0.86
15.8 ± 0.40
15.6 ± 0.40
28.8 ± 0.74
28.6 ± 1.15
PLT (x105 cells/μL)
11.4 ± 7.35
11.3 ± 11.17
21.7 ± 1.63
26.0 ± 4.76
71.7 ± 1.81
67.2 ± 5.78
1.40 ± 0.35
1.30 ± 0.44
Traditional medicine in Asian countries commonly combines herbs to create multi-herbal formulas for treating target diseases, and the use of these formulas has been verified scientifically as complementary or alternative cancer therapies. Especially, advanced diseases including cancer require the multi-targeting treatment in cellular signaling pathways, herbal formulas may achieve better therapeutic efficacy according to the synergy than that of a single herb. However, multi-herbal formulas must be pre-clinically evaluated to accurately compare traditional herbal medicines with modern therapeutics. In the present study, 14 standards in 12 constituent herbals from GBT were identified in the GBT samples. A previous study has reported that decursin, decursinol, and decursinol angelate from A. gigas Nakai indicate the anti-cancer effects in colon and breast carcinoma cells via inhibition of proliferation and induction of apoptosis[19, 20]. Ginsenoside Rg1 and Rb1 from P. ginseng have anti-proliferative effect in colon cancer via cell cycle arrest and apoptosis induction. A recent study has reported that vanilylacetone from Z. offcinale Rosc. has anti-carcinogenic properties against colon cancer, and 6-gingerol has apoptotic effect against breast and prostate carcinoma cells via modulation of STAT3 and MAPK signaling pathway[22, 23]. In addition, formononetin from A. membranaceus induces apoptosis in prostate cancer cells via enhancing the Bax/Bcl-2 ratios and regulating the p38 phosphorylation. Other reports have demonstrated that sesquiterpenoids from A. ovate, such as atractylenolide I, II, and III, exists anti-tumor effect in lung carcinoma cells via caspase-dependent apoptosis pathway[25, 26]. These reports suggest that the anti-cancer effect of GBT might be related to these active components. In this study, GBT induced apoptosis in A431 human squamous carcinoma cells by inhibiting cancer cell proliferation without affecting the viability of HaCaT keratinocytes or mouse primary hepatocytes. Based on these preliminary observations, we assessed the molecular mechanism of the anti-cancer effects of GBT on A431 cells. GBT increased the formation of fragmented DNA ladders as well as other apoptotic features such as chromatin condensation. In Western blot analysis, GBT affected the expression of pro- and anti-apoptotic proteins, espectially, GBT enhanced the activation of caspases in A431 cells. Caspases are a family of cysteine proteases that, when inactive, exist in proenzyme form. Upon the induction of apoptosis, they become activation via a self-amplifying cascade. The activation of initiator caspases such as caspases-8, -9, and -10 by pro-apoptotic signals leads to downstream activation of the effector caspases-3, -6, and -7. The caspase cascades are divided into two major pathways: an extrinsic pathway initiated by ligand-mediated activation of cell surface death receptors, and an intrinsic pathway activated by intracellular signals from the mitochondria. In the present study, the activation of caspase-8 and -3 and the cleavage of PARP correlated precisely with the DNA fragmented ladder after treatment with GBT, whereas the levels of procaspase-9 decreased slightly, without the appearance of the cleaved form. The Bcl-2 family of proteins, including Bid, Bcl-2, and Bax, regulate the activation of caspase-9. In our study, GBT-stimulated active caspase-8 did not increase the levels of truncated Bid, although total Bid levels were reduced. Our data suggest that the activation of caspase-8 by GBT results in the direct activation of caspase-3, which is typical of the extrinsic apoptotic pathway, suggesting that GBT activates extrinsic apoptosis to have anti-cancer effects on A431 cells. We also found that GBT stimulated the phosphorylation of MAPKs and p53, signaling pathways that are required for cell growth and tumorigenesis. MAPK cascades including ERK, p38, and JNK, regulate cellular processes including proliferation, differentiation, and apoptosis. Especially, Pharmacological modulation of MAPK singals has been confirmed in previous studies to influence the apoptotic response to anti-tumor agents. For example, ERK activation by treatment with cisplatin plays a key role in mediating cisplatin-induced apoptosis of HeLa human cervical carcinoma cells, which induces caspase activation. Another example is represent that the role of MAPK and p53 pathways in cancer cells is associated with anti-cancer effect of chemotherapeutic agents such as vinblastine, doxorubicin and etoposide. In the present study, we identified that GBT treatment activated the ERK, p38, and JNK signals, which retained during apoptosis of A431 cells. In addition, inhibition of MAPK signaling by the specific inhibitors (PD98059, ERK inhibitor; SB203580, p38 inhibitor; SP600125, JNK inhibitor) protected cells from the cytotoxic effects of GBT, suggesting that activation of MAPK cascades play a opposite role in A431 cell proliferation. MAPKs are activated upon exposure to stress, leading to the phosphorylation and activation of p53. The activation of MAPKs can activate p53 to phosphorylation form at various serine residues, resulting in p53-mediated cellular responses such as DNA repair, cell cycle arrest, and the induction of apoptosis. The phosphorylation of p53 at serine 15 (p53-Ser15P) by p38 or ERK results in the induction of apoptosis in cancer cells[34, 35]. In contrast, activated JNK plays a direct role in the phosphorylation of p53 at serine 20, leading to the activation and stabilization of p53. In cell cycle progression relevant to cell proliferation, furthermore, the activation of p53 causes cell cycle arrest in the G1 phase, which mediated by p21 and p27, inhibitors of cyclin/CDK complexes[36, 37]. In present study, the activation of ERK, p38, and JNK by GBT corresponded with increase of p53-Ser15P expression in A431 cells, which caused the up-regulation of p21 and p27 expressions during GBT-induced apoptosis. Taken together, these results strongly suggest that activation of MAPK cascades by GBT induces phosphorylation of p53, which results in induction of apoptosis for A431 cells.
Based on results demonstrated in A431 cells in vitro, we performed xenograft assay in athymic nude mice. In the evaluation of inhibitory effect of GBT against tumor growth after 15 days of daily oral administration, GBT significantly suppresses tumor growth of subcutaneously injected A431 cells without side effects such as body weight loss, organ abnormalities, and hematological/serological parameter changes. Therefore, GBT has a significant anti-tumorigenic effect in vivo.
This study assessd the efficacy of GBT anti-cancer effect in vitro and vivo. Our results strongly demonstrated that GBT induced apoptosis by regulating the activity of MAPK cascades and p53 in A431 cells. Further, oral administration of GBT obviously inhibited in vivo tumor cell growth of A431 cells without causing systemic toxicity. Resultingly, we suggest that GBT has potential as a herbal medicine for controlling malignant tumor growth.
This work was supported by a grant (K14050) awarded to the Korean Institute of Oriental Medicine by the Ministry of Education, Science and Technology (MEST), Korea. Further, we thank Ju Hye Lee for helpful experiment in this study.
- Diepgen TL, Mahler V: The epidemiology of skin cancer. Br J Dermatol. 2002, 146 (Suppl 61): 1-6.View ArticlePubMedGoogle Scholar
- Weinstein MC, Brodell RT, Bordeaux J, Honda K: The art and science of surgical margins for the dermatopathologist. Am J Dermatopathol. 2012, 34 (7): 737-745. 10.1097/DAD.0b013e31823347cb.View ArticlePubMedGoogle Scholar
- Sauter ER, Herlyn M, Liu SC, Litwin S, Ridge JA: Prolonged response to antisense cyclin D1 in a human squamous cancer xenograft model. Clin Cancer Res. 2000, 6 (2): 654-660.PubMedGoogle Scholar
- Trakatelli M, Ulrich C, del Marmol V, Euvrard S, Stockfleth E, Abeni D: Epidemiology of nonmelanoma skin cancer (NMSC) in Europe: accurate and comparable data are needed for effective public health monitoring and interventions. Br J Dermatol. 2007, 156 (Suppl 3): 1-7.View ArticlePubMedGoogle Scholar
- Tohda C, Ichimura M, Bai Y, Tanaka K, Zhu S, Komatsu K: Inhibitory effects of Eleutherococcus senticosus extracts on amyloid beta(25–35)-induced neuritic atrophy and synaptic loss. J Pharmacol Sci. 2008, 107 (3): 329-339. 10.1254/jphs.08046FP.View ArticlePubMedGoogle Scholar
- Busta I, Xei HS, Kim MS: The use of Gui-Pi-Tang in small animals with immune-mediated blood disorders. J Vet Clin. 2009, 26: 181-184.Google Scholar
- Kang IH, Lee I, Han SH, Moon BS: Effects of Gwibitang on glutamate-induced apoptosis in C6 glial cells. J Korean Orient Med. 2001, 22: 45-57.Google Scholar
- Kim HJ, Choi JH, Lim SW: The defensive effect of Keuibi-tang on the gastric mucous membrane of mouse injured by stress and ethanol. J Orient Med. 2003, 24: 155-168.Google Scholar
- Ikeda A, Higashio S, Ushiroyama T: Experience with administration of kamikihito with chemotherapy and palliative care in patients with gynecologic cancer. Recent Prog Kampo Med Obstet Gynecol. 2003, 20: 152-155.Google Scholar
- Kundoor V, Zhang X, Bommareddy A, Khalifa S, Fahmy H, Dwivedi C: Chemopreventive effects of sarcotriol on ultraviolet B-induced skin tumor development in SKH-1 hairless mice. Marine Drugs. 2007, 5 (4): 197-207. 10.3390/md504197.View ArticlePubMedPubMed CentralGoogle Scholar
- Sarfaraz S, Adhami VM, Syed DN, Afaq F, Mukhtar H: Cannabinoids for cancer treatment: progress and promise. Cancer Res. 2008, 68 (2): 339-342. 10.1158/0008-5472.CAN-07-2785.View ArticlePubMedGoogle Scholar
- Hamamura K, Goldring MB, Yokota H: Involvement of p38 MAPK in regulation of MMP13 mRNA in chondrocytes in response to surviving stress to endoplasmic reticulum. Arch Oral Biol. 2009, 54 (3): 279-286. 10.1016/j.archoralbio.2008.11.003.View ArticlePubMedGoogle Scholar
- Fan M, Chambers TC: Role of mitogen-activated protein kinases in the response of tumor cells to chemotherapy. Drug Resist Updat. 2001, 5: 253-267.View ArticleGoogle Scholar
- Dent P, Grant S: Pharmacologic interruption of the mitogen-activated extracellular-regulated kinase/mitogen-activated protein kinase signal transduction pathway: potential role in promoting cytotoxic drug action. Clin Cancer Res. 2001, 7: 775-783.PubMedGoogle Scholar
- Yim NH, Lee JH, Cho WK, Yang MC, Kwak DH, Ma JY: Decursin and decursinol angelate from Angelica gigas Nakai induce apoptosis via induction of TRAIL expression on cervical cancer cells. Eur J Integr Med. 2011, 3: 299-307. 10.1016/j.eujim.2011.09.007.View ArticleGoogle Scholar
- Son JY, Choi HY, Kim JD: Anticancer and related immunomodulatory effects of Kwibi-tang on non-small cell lung carcinoma, NCI-H520, Xenograft mice. Korean J Interal Med. 2012, 33: 387-404.Google Scholar
- Corson TW, Crews GM: Molecular understanding and modern application of traditional medicines: triumphs and trials. Cell. 2007, 130: 769-774. 10.1016/j.cell.2007.08.021.View ArticlePubMedPubMed CentralGoogle Scholar
- Lee EO, Lee HJ, Hwang HS, Ahn KS, Chae C, Kang KS, Lu J, Kim SH: Potent inhibition of Lewis lung cancer growth by heyneanol A from the roots of Vitis amurensis through apoptotic and anti-angiogenic activities. Carcinogenesis. 2006, 27 (10): 2059-2069. 10.1093/carcin/bgl055.View ArticlePubMedGoogle Scholar
- Son SH, Park KK, Park SK, Kim YC, Kim YS, Lee SK, Cung WY: Decursin and decursinol from Angelica gigas inhibit the lung metastasis of murin colon carcinoma. Phytother Res. 2011, 25 (7): 959-964. 10.1002/ptr.3372.View ArticlePubMedGoogle Scholar
- Jiang C, Guo J, Wang Z, Xiao B, Lee HJ, Lee EO, Kim SH, Lu J: Decursin and decursinol angelate inhibit estrogen-stimulated and estrogen-independent growth and survival of breast cancer cells. Breast Cancer Res. 2007, 9 (6): R77-10.1186/bcr1790.View ArticlePubMedPubMed CentralGoogle Scholar
- Wang CZ, Xie JT, Zhang B, Ni M, Fishbein A, Aung HH, Mehendale SR, Du W, He TC, Yuan CS: Chemopreventive effects of Panax notoginseng and its major constituents on SW480 human colorectal cancer cells. Int J Oncol. 2007, 31 (5): 1149-1156.PubMedPubMed CentralGoogle Scholar
- Vinothkumar R, Vinothkumar R, Sudha M, Nalini N: Chemopreventive effect of zingerone against colon carcinogenesis induced by 1,2-dimethylhydrazine in rats. Eur J Cancer Prev. 2014, 23 (5): 361-371. 10.1097/CEJ.0b013e32836473ac.View ArticlePubMedGoogle Scholar
- Kim SM, Kim C, Bae H, Lee JH, Baek SH, NAm D, Cung WS, Shim BS, Lee SG, Kim SH, Sethi G, Ahn KS: 6-shogaol exerts anti-proliferative and pro-apoptotic effects through the modulation of STAT3 and MAPKs signaling pathways. Mol Carcinog. 2014, doi:10.1002/mc 22184Google Scholar
- Zhang X, Bi L, Ye Y, Chen J: Formononetin induces apoptosis in PC-3 prostate cancer cells through enhancing the Bax/Bcl-2 ratios and regulating the p38/Akt pathway. Nutr Cancer. 2014, 66 (4): 656-661. 10.1080/01635581.2014.894098.View ArticlePubMedGoogle Scholar
- Liu H, Zhu Y, Zhang T, Zhao Z, Zhao Y, Cheng P, Li H, Gao H, Su X: Anti-tumor effects of atractylenolide I isolated from Atractylodes macrocephala in human lung carcinoma cell lines. Molecules. 2013, 18 (11): 13357-13368. 10.3390/molecules181113357.View ArticlePubMedGoogle Scholar
- Kang TH, Bang JY, Kim MH, Kang IC, Kim HM, Jeong HJ: Atractylenolide III, a sesquiterpenoid, induces apoptosis in human lung carcinoma A549 cells via mitochondria-mediated death pathway. Food Chem Toxicol. 2011, 49 (2): 514-519. 10.1016/j.fct.2010.11.038.View ArticlePubMedGoogle Scholar
- Saraste A, Pulkki K: Morphologic and biochemical hallmarks of apoptosis. Cardiovasc Res. 2000, 45 (3): 528-537. 10.1016/S0008-6363(99)00384-3.View ArticlePubMedGoogle Scholar
- Sheikh MS, Huang Y: Death receptors as targets of cancer therapeutics. Curr Cancer Drug Targets. 2004, 4 (1): 97-104. 10.2174/1568009043481597.View ArticlePubMedGoogle Scholar
- Reyes-Zurita FJ, Rufino-Palomares EE, Medina PP, Leticia Garcia-Salguero E, Peragon J, Cascante M, Lupianez JA: Antitumour activity on extrinsic apoptotic targets of the triterpenoid maslinic acid in p53-deficient Caco-2 adenocarcinoma cells. Biochimie. 2013, 95 (11): 2157-2167. 10.1016/j.biochi.2013.08.017.View ArticlePubMedGoogle Scholar
- Murphy LO, Blenis J: MAPK signal specificity: the right place at the right time. Trends Biochem Sci. 2006, 31 (5): 268-275. 10.1016/j.tibs.2006.03.009.View ArticlePubMedGoogle Scholar
- Wang X, Martindale JL, Holbrook NJ: Requirement for ERJK activation in cisplatin-induced apoptosis. J Biol Chem. 2000, 275: 39435-39443. 10.1074/jbc.M004583200.View ArticlePubMedGoogle Scholar
- Cheryl BF, Christopher SL, Lihua D, Mary EG, Toria H, Dominika S, Kaushal GP, Timothy CC: The JNK, ERK and p53 pathways play distinct roles in apoptosis mediated by the antitumor agents vinblastine, doxorubicin, and etoposide. Biol Pharmacol. 2003, 66: 459-469.Google Scholar
- Jiang C, Lee HJ, Li GX, Guo J, Malewicz B, Zhao Y, Lee EO, Lee HJ, Lee JH, Kim MS, Lu J: Potent antiandrogen and androgen receptor activities of an Angelica gigas-containing herbal formulation: identification of decursin as a novel and active compound with implications for prevention and treatment of prostate cancer. Cancer Res. 2006, 66 (1): 453-463. 10.1158/0008-5472.CAN-05-1865.View ArticlePubMedGoogle Scholar
- Kim SJ, Hwang SG, Shin DY, Kang SS, Chun JS: p38 kinase regulates nitric oxide-induced apoptosis of articular chondrocytes by accumulating p53 via NFkappa B-dependent transcription and stabilization by serine 15 phosphorylation. J Biol Chem. 2002, 277 (36): 33501-33508. 10.1074/jbc.M202862200.View ArticlePubMedGoogle Scholar
- She QB, Bode AM, Ma WY, Chen NY, Dong Z: Resveratrol-induced activation of p53 and apoptosis is mediated by extracellular-signal-regulated protein kinases and p38 kinase. Cancer Res. 2001, 61 (4): 1604-1610.PubMedGoogle Scholar
- Koljonen V: Merkel cell carcinoma. World J Surg Oncol. 2006, 4: 7-10.1186/1477-7819-4-7.View ArticlePubMedPubMed CentralGoogle Scholar
- Wang X, Gorospe M, Huang Y, Holbrook NJ: p27Kip1 overexpression causes apoptotic death of mammalian cells. Oncogene. 1997, 15 (24): 2991-2997. 10.1038/sj.onc.1201450.View ArticlePubMedGoogle Scholar
- The pre-publication history for this paper can be accessed here:http://www.biomedcentral.com/1472-6882/14/344/prepub
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.