山竹子素在宫颈癌中的抗肿瘤活性探讨

目的:探讨山竹子素(garcinol)在宫颈癌中的抗肿瘤活性。方法:采用低剂量、中剂量和高剂量的山竹子素处理宫颈癌细胞。CCK-8实验检测细胞活力。EdU实验检测细胞增殖。流式细胞术检测细胞周期和凋亡。划痕实验检测细胞迁移。Transwell实验检测细胞侵袭。构建荷瘤小鼠模型,检测山竹子素对宫颈癌细胞体内成瘤能力的影响。免疫组化检测肿瘤组织Ki-67增殖指数和凋亡水平。HE染色检测山竹子素对荷瘤小鼠心、肝、肾、脾和肺的毒性作用。结果:山竹子素呈浓度依赖性的抑制宫颈癌细胞的活力和增殖,诱导细胞周期阻滞效应和细胞凋亡,降低细胞的迁移和侵袭能力(P<0.05)。山竹子素显著抑制宫颈癌细胞的异种移植瘤的形成和生长,降低Ki-67增殖指数,提高凋亡水平(P<0.05)。山竹子素对荷瘤小鼠心、肝、肾、脾和肺无明显毒性作用。结论:山竹子素在宫颈癌中具有良好的抗肿瘤活性。     

Demethylzeylasteral (ZST93) inhibits cell growth and enhances cell chemosensitivity to gemcitabine in human pancreatic cancer cells via apoptotic and autophagic pathways

The overall 5‐year survival rate of patients with human pancreatic cancer remains less than 8% because of its aggressive growth, early metastasis and resistance to conventional chemoradiotherapy. It is essential to develop innovative and effective therapeutic agents to improve its prognosis. Demethylzeylasteral (ZST93) is a novel triterpenoid monomer extracted from the xylem of Tripterygium roots. Our study aimed to assess the effects of ZST93 on cell proliferation and its role in the chemosensitivity to gemcitabine in human pancreatic cancer cells. The effects of ZST93 on cancer cell proliferation, cell cycle distribution, apoptosis and autophagy were evaluated in various human pancreatic cancer cell lines, and the antitumor effects of ZST93 alone and in combination with gemcitabine were identified in a xenograft mouse model. The results showed that ZST93 could inhibit the proliferation of pancreatic cancer cells and arrest cell cycle at G0/G1 phase by regulating the expression of Cyclin D1 and Cyclin A2. Moreover, ZST93 killed pancreatic cancer cells through two different mechanisms: inducing autophagic cell death at low concentrations and apoptotic cell death at high concentrations. Furthermore, ZST93 could enhance the chemosensitivity of pancreatic cancer cells to gemcitabine both in vitro and in vivo through modulation of the cross talk between autophagy and apoptosis. ZST93 is a potential therapeutic agent for developing novel therapeutic strategies in human pancreatic cancer.     

In vivo antitumor effect of the mTOR inhibitor CCI-779 and gemcitabine in xenograft models of human pancreatic cancer

Mammalian target of rapamycin (mTOR) is considered to be a major effector of cell growth and proliferation that controls protein synthesis through a large number of downstream targets. We investigated the expression of the phosphatidylinositol 3'-kinase (PI3K)/mTOR signaling pathway in human pancreatic cancer cells and tissues, and the in vivo antitumor effects of the mTOR inhibitor CCI-779 with/without gemcitabine in xenograft models of human pancreatic cancer. We found that the Akt, mTOR and p70 S6 kinase (S6K1) from the PI3K/mTOR signaling pathway were activated in all of the pancreatic cancer cell lines examined. When surgically resected tissue specimens of pancreatic ductal adenocarcinoma were examined, phosphorylation of Akt, mTOR and S6K1 was detected in 50, 55 and 65% of the specimens, respectively. Although CCI-779 had no additive or synergistic antiproliferative effect when combined with gemcitabine in vitro, it showed significant antitumor activity in the AsPC-1 subcutaneous xenograft model as both a single agent and in combination with gemictabine. Furthermore, in the Suit-2 peritoneal dissemination xenograft model, the combination of these 2 drugs achieved significantly better survival when compared with CCI-779 or gemcitabine alone. These results demonstrate promising activity of the mTOR inhibitor CCI-779 against human pancreatic cancer, and suggest that the inhibition of mTOR signaling can be exploited as a potentially tumor-selective therapeutic strategy.     

Substituted titanocenes induce caspase-dependent apoptosis in human epidermoid carcinoma cells in vitro and exhibit antitumour activity in vivo

Titanocene compounds are a novel series of agents that exhibit cytotoxic effects in a variety of human cancer cells in vitro and in vivo. In this study, the antiproliferative activity of two titanocenes (Titanocenes X and Y) was evaluated in human epidermoid cancer cells in vitro. Titanocenes X and Y induce apoptotic cell death in epidermoid cancer cells, with IC50 values that are comparable to cisplatin. Characterisation of the cell death pathway induced by titanocene compounds in A431 cells revealed that apoptosis is preceded by cell cycle arrest and the inhibition of cell proliferation. The induction of apoptosis is dependent on the activation of caspase-3 and -7 but not caspase-8. Furthermore, the antitumour activity of Titanocene Y was tested in an A431 xenograft model of epidermoid cancer. Results indicate that Titanocene Y significantly reduced the growth of A431 xenografts with an antitumour effect similar to cisplatin. These results suggest that titanocenes represent a novel series of promising antitumour agents.     

FR901228, a novel histone deacetylase inhibitor, induces cell cycle arrest and subsequent apoptosis in refractory human pancreatic cancer cells

Histone deacetylase (HDAC) inhibitors have antiproliferative activity against human cancer cells via cell cycle arrest, differentiation, and apoptosis. However, no report has focused on the apoptotic potential of HDAC inhibitors in refractory human pancreatic cancer. This study was designed to examine the apoptotic potential of FR901228, a novel HDAC inhibitor, in five human pancreatic cancer cell lines: Capan-1, BxPC-3, HPAF, Panc-1, and MIAPaCa-2. FR901228 markedly inhibited the proliferation of all five cell lines (IC50: 1-500 nM), with the greatest effect in MIAPaCa-2 cells. Treatment of each cell line with FR901228 (10-100 nM) caused cell cycle arrest at the G1 or G2/M phase and subsequent apoptosis. FR901228 induced expression of hyperacetylated histone H3 after 3 h of treatment and overexpression of p21Waf-1 after 6 h. In addition, FR901228 induced apoptosis by activating caspase-3, which led to cleavage of p21Waf-1 into a 15-kDa breakdown product and drove cancer cells from cell cycle arrest into apoptosis. FR901228 also decreased the protein level of survivin dramatically. Our results show that FR901228 markedly inhibits the growth of pancreatic cancer cells, not only through cell cycle arrest, but also through subsequent apoptosis; this was accompanied by caspase-3 activation, survivin degradation, and p21Waf-1 cleavage. FR901228 may prove clinically useful as an agent for refractory pancreatic cancers.     

Oridonin enhances antitumor activity of gemcitabine in pancreatic cancer through MAPK-p38 signaling pathway

Gemcitabine is currently the best treatment available for pancreatic cancer (PaCa); however, patients with the disease develop resistance to the drug over time. Agents that can either enhance the effects of gemcitabine or overcome chemoresistance to the drug are required for the treatment of PaCa. Oridonin is one such agent which is safe and multitargeted, and has been linked with the suppression of survival, proliferation, invasion and angiogenesis of cancer. In this study, we investigated whether oridonin could sensitize PaCa to gemcitabine in vitro and in vivo. In vitro, oridonin inhibited the proliferation of the PaCa cell line, BxPC-3, potentiated the apoptosis induced by gemcitabine, induced G1 cell cycle arrest and activated p38 and p53; these results were significant when oridonin was combined with gemcitabine. In vivo, we found that oridonin significantly suppressed tumor growth and this effect was further enhanced by gemcitabine (P<0.05). Tumors from nude mice injected with BxPC-3 PaCa cells and treated with a combination of oridonin and gemcitabine showed a significant upregulation in p38 and p53 activation (P<0.05 vs. control, P<0.05 vs. gemcitabine or oridonin alone). Taken together, our results demonstrate that oridonin can potentiate the effects of gemcitabine in PaCa through the mitogen-activated protein kinase (MAPK)-p38 signaling pathway, which is dependent on p53 activation.     

Enhanced antitumor effect of combined triptolide and ionizing radiation.

PURPOSE: The lack of effective treatment for pancreatic cancer results in a very low survival rate. This study explores the enhancement of the therapeutic effect on human pancreatic cancer via the combination of triptolide and ionizing radiation (IR). EXPERIMENTAL DESIGN: In vitro AsPC-1 human pancreatic cancer cells were treated with triptolide alone, IR alone, or triptolide plus IR. Cell proliferation was analyzed with sulforhodamine B (SRB) method and clonogenic survival; comparison of apoptosis induced by the above treatment was analyzed by annexin V-propidium iodide (PI) staining. Furthermore, the expression of apoptotic pathway intermediates was measured by the assay of caspase activity and Western blot. Mitochondrial transmembrane potential was determined by JC-1 assay. In vivo, AsPC-1 xenografts were treated with 0.25 mg/kg triptolide, 10 Gy IR, or triptolide plus IR. The tumors were measured for volume and weight at the end of the experiment. Tumor tissues were tested for terminal nucleotidyl transferase-mediated nick end labeling (TUNEL) and immunohistochemistry. RESULTS: The combination of triptolide plus IR reduced cell survival to 21% and enhanced apoptosis, compared with single treatment. In vivo, tumor growth of AsPC-1 xenografts was reduced further in the group treated with triptolide plus IR compared with single treatment. TUNEL and immunohistochemistry of caspase-3 cleavage in tumor tissues indicated that the combination of triptolide plus IR resulted in significantly enhanced apoptosis compared with single treatments. CONCLUSIONS: Triptolide in combination with ionizing radiation produced synergistic antitumor effects on pancreatic cancer both in vitro and in vivo and seems promising in the combined modality therapy of pancreatic cancer.     

Synergistic antitumor activity of ZD6474, an inhibitor of vascular endothelial growth factor receptor and epidermal growth factor receptor signaling, with gemcitabine and ionizing radiation against pancreatic cancer.

PURPOSE: Standard treatments have modest effect against pancreatic cancer, and current research focuses on agents targeting molecular pathways involved in tumor growth and angiogenesis. This study investigated the interactions between ZD6474, an inhibitor of tyrosine kinase activities of vascular endothelial growth factor receptor-2 and epidermal growth factor receptor (EGFR), gemcitabine, and ionizing radiation in human pancreatic cancer cells and analyzed the molecular mechanisms underlying this combination. EXPERIMENTAL DESIGN: ZD6474, ionizing radiation, and gemcitabine, alone or in combination, were given in vitro to MIA PaCa-2, PANC-1, and Capan-1 cells and in vivo to MIA PaCa-2 tumor xenografts. The effects of treatments were studied by the evaluation of cytotoxicity, apoptosis, cell cycle, EGFR and Akt phosphorylation, modulation of gene expression of enzymes related to gemcitabine activity (deoxycytidine kinase and ribonucleotide reductase), as well as vascular endothelial growth factor immunohistochemistry and microvessel count. RESULTS: In vitro, ZD6474 dose dependently inhibited cell growth, induced apoptosis, and synergistically enhanced the cytotoxic activity of gemcitabine and ionizing radiation. Moreover, ZD6474 inhibited phosphorylation of EGFR and Akt and triggered cell apoptosis. PCR analysis showed that ZD6474 increased the ratio between gene expression of deoxycytidine kinase and ribonucleotide reductase. In vivo, ZD6474 showed significant antitumor activity alone and in combination with radiotherapy and gemcitabine, and the combination of all three modalities enhanced MIA PaCA-2 tumor growth inhibition compared with gemcitabine alone. CONCLUSIONS: ZD6474 decreases EGFR and Akt phosphorylation, enhances apoptosis, favorably modulates gene expression in cancer cells, and acts synergistically with gemcitabine and radiotherapy to inhibit tumor growth. These findings support the investigation of this combination in the clinical setting.     

1,25D3 Enhances antitumor activity of gemcitabine and cisplatin in human bladder cancer models

BACKGROUND:

1,25 dihydroxyvitamin D₃ (1,25D₃) potentiates the cytotoxic effects of several common chemotherapeutic agents. The combination of gemcitabine and cisplatin is a current standard chemotherapy regimen for bladder cancer. The authors investigated whether 1,25D₃ could enhance the antitumor activity of gemcitabine and cisplatin in bladder cancer model systems.

METHODS:

Human bladder cancer T24 and UMUC3 cells were pretreated with 1,25D₃ followed by gemcitabine and cisplatin. Apoptosis was assessed by annexin V staining. Caspase activation was examined by immunoblot analysis and substrate‐based caspase activity assay. The cytotoxic effects were examined by using 3‐(4,5‐Dimethyl‐2‐thiazolyl)‐2,5‐diphenyl‐2H‐tetrazolium bromide (MTT) and in vitro clonogenic assay. p73 protein levels were assessed by immunoblot analysis. Knockdown of p73 was achieved by siRNA. The in vivo antitumor activity was assessed by in vivo excision clonogenic assay and tumor regrowth delay in the T24 xenograft model.

RESULTS:

1,25D₃ pretreatment enhanced gemcitabine and cisplatin‐induced apoptosis and the activities of caspases 8, 9, and 3 in T24 and UMUC3 cells. 1,25D₃ synergistically reduced gemcitabine and cisplatin‐suppressed surviving fraction in T24 cells. 1,25D₃, gemcitabine, or cisplatin induced p73 accumulation, which was enhanced by gemcitabine and cisplatin or 1,25D₃ and gemcitabine and cisplatin. p73 expression was lower in human primary bladder tumor tissue compared with adjacent normal tissue. Knockdown of p73 increased clonogenic capacity of T24 cells treated with 1,25D₃, gemcitabine and cisplatin, or 1,25D₃ and gemcitabine and cisplatin. 1,25D₃ and gemcitabine and cisplatin combination enhanced tumor regression compared with 1,25D₃ or gemcitabine and cisplatin alone.

CONCLUSIONS:

1,25D₃ potentiates gemcitabine and cisplatin‐mediated growth inhibition in human bladder cancer models in vitro and in vivo, which involves p73 induction and apoptosis. Cancer 2010; 116:3294‐303. © 2010 American Cancer Society.     

Antiangiogenic treatment with three thrombospondin-1 type 1 repeats versus gemcitabine in an orthotopic human pancreatic cancer model.

PURPOSE: In this study, we investigated the antitumor efficacy of thrombospondin-1 three type 1 repeats (3TSR), the antiangiogenic domain of thrombospondin-1, in comparison and in combination with gemcitabine, in an orthotopic pancreatic cancer model. EXPERIMENTAL DESIGN: Human pancreatic cancer cells were injected into the pancreas of severe combined immunodeficient mice. The animals were treated with 3TSR, gemcitabine, 3TSR plus gemcitabine, or vehicle for 3 weeks. Subsequently, the effects of 3TSR and/or gemcitabine on tumor growth, tumor necrosis, microvessel density, cancer cell proliferation, apoptosis, and endothelial cell apoptosis were analyzed. RESULTS: After 3 weeks of treatment, 3TSR reduced tumor volume by 65%, and gemcitabine by 84%. Tumor volume was not statistically different between gemcitabine group and combinatorial treatment group. Extensive necrotic areas were observed in tumors from 3TSR-treated mice, whereas tumors from gemcitabine and combinatorially treated mice were less necrotic than control tumors. 3TSR reduced tumor microvessel density and increased tumor blood vessel endothelial cell apoptosis. In contrast, gemcitabine induced apoptosis and inhibited proliferation of cancer cells. CONCLUSION: 3TSR, the antiangiogenic domain of thrombospondin-1, showed comparable antitumor efficacy to gemcitabine in a human pancreatic cancer orthotopic mouse model. No synergistic effect was found when the two drugs were combined and possible reasons are discussed in detail. A delicate balance between normalization and excessive regression of tumor vasculature is important when initiating alternative combinatorial regimens for treatment of patients with pancreatic cancer.     

Bufalin exerts antitumor effects by inducing cell cycle arrest and triggering apoptosis in pancreatic cancer cells

As one of the most aggressive human malignancies, pancreatic cancer is a leading cause of cancer-related deaths worldwide and only about 4 % of patients will live 5 years after diagnosis. Eighty to approximately eighty-five percent of patients are diagnosed with an unresectable or metastatic disease, which is correlated with poor prognosis and low survival rate. Therefore, it is tremendously significant to exploit novel chemicals to prevent and treat pancreatic cancer. Previous research and clinical studies have demonstrated that many natural products derived from traditional Chinese medicine (TCM) such as camptothecin derivatives and vinca alkaloids could be effective antitumor compounds, hinting that TCM is a promising source for developing new antitumor drugs. In this report, we investigated the effects of bufalin, a primary active ingredient of the traditional Chinese medicine Chan-Su, on pancreatic cancer cell lines PANC-1 and CFPAC-1 and studied the underlying molecular mechanism. We found that exposure to bufalin could suppress the proliferation of pancreatic cancer cells time and dose dependently. We used flow cytometry to study the effects of bufalin on apoptosis and cell cycle distribution in PANC-1 and CFPAC-1 cells. The results indicated that bufalin could significantly induce both apoptosis and G2/M cell cycle arrest in pancreatic cancer cells. With western blotting, we found that the expression level of an antiapoptotic protein heat shock protein 27 (Hsp27) and its partner molecule p-Akt was decreased upon the treatment with bufalin. Besides, bufalin activated pro-caspase-3 and pro-caspase-9 and modulated the expression level of Bcl-2 and Bax. These data suggested that bufalin may trigger apoptosis by targeting Hsp27, which could inhibit apoptosis by interfering with key apoptotic proteins. The influence on the level of cylinB1, CDK1, and p21 was also observed after bufalin treatment, and the relationship between Hsp27 and the cell cycle-related proteins mentioned above deserves much more research. In addition, our data showed that bufalin could enhance the growth inhibition effect of gemcitabine in above pancreatic cancer cells. Taken together, bufalin might be worthy of further study for its potential as a therapeutic agent for pancreatic cancer treatment.     

Enhanced antitumor efficacy by the combination of emodin and gemcitabine against human pancreatic cancer cells via downregulation of the expression of XIAP in vitro and in vivo

XIAP and NF-κB play an important role in chemotherapy resistance in pancreatic cancer. The purpose of this study was to explore the role of XIAP and NF-κB in potentiating the antitumor effect of gemcitabine by emodin in pancreatic cancer. SW1990 cells were treated by sodium chloride, gemcitabine, emodin or their combination (gemcitabine plus emodin). Cellular proliferation and apoptosis were detected by Cell Counting kit-8 (CCK-8) assay and flow cytometry in?vitro. The combination therapy more significantly inhibited SW1990 cell growth and induced a higher percentage of apoptosis than monotherapy. Gemcitabine upregulated the expression of XIAP and NF-κB, while emodin or emodin plus gemcitabine downregulated them compared to the control group in?vitro. SW1990 cells were used to establish orthotopic pancreatic tumor models in nude mice. Tumor-bearing mice were treated with sodium chloride, emodin, gemcitabine or their combination. After being treated for 4 weeks, the nude mice were imaged with high-resolution positron emission tomography (microPET) and fluorine-18-labeled fluorodeoxyglucose (18F-FDG) to detect the tumor/non-tumor ratio (T/NT ratio) and standard uptake value (SUV). The mice were sacrificed to determine tumor weight. The combination of emodin and gemcitabine showed more significant reduction in the T/NT ratio, SUV and tumor weight compared to monotherapy. The mRNA levels and the protein expression of XIAP and NF-κB were upregulated in the gemcitabine group, while they were downregulated in the emodin group and the combination group in?vivo. Ki-67 prolif-eration index and TUNEL assay results also showed that emodin enhanced tumor apoptosis induced by gemcitabine in?vivo. This study suggests that emodin enhances the antitumor effect of gemcitabine in SW1990 pancreatic cancer in?vitro and in?vivo, which may be via the downregulation of NF-κB expression, thus inhibiting the expression of XIAP.     

The effects of cyclooxygenase-2 gene silencing by siRNA on cell proliferation, cell apoptosis, cell cycle and tumorigenicity of Capan-2 human pancreatic cancer cells

The prognosis of pancreatic cancer is still very poor. No specific effective gene therapy for pancreatic cancer has been found. As a key enzyme of the metabolic process of arachidonic acid, cyclooxygenase-2 (COX-2) has been found to be closely related to the tumorigenesis of epithelial cancers. However, the antitumor effect of small interfering RNA (siRNA) targeting COX-2 in pancreatic cancer has not yet been verified. Therefore, the aim of this study was to investigate the effects of COX-2 gene silencing by siRNA on cell proliferation, cell apoptosis, cell cycle and tumorigenicity of pancreatic cancer cells. COX-2 mRNA was detected by RT-PCR and real-time PCR. COX-2 protein was detected by Western blotting. The cell proliferation was measured by cell counting using microscopy. The cell apoptosis and cell cycle were measured by flow cytometry. The tumorigenicity of Capan-2 pancreatic cancer cells transfected with COX-2 siRNA was evaluated using a nude mouse xenograft model. The expression of COX-2 mRNA as well as COX-2 protein were downregulated after COX-2 siRNA transfection. COX-2 siRNA could inhibit the growth of Capan-2 cells significantly by decreasing the cell proliferation, increasing cell apoptosis and regulating cell cycle as well. In vivo experiments demonstrated that the mean volume and weight of subcutaneous xenografts in nude mice derived from Capan-2 cells transfected with COX-2 siRNA were significantly decreased. COX-2 siRNA could inhibit the growth of Capan-2 pancreatic cancer cells and also decrease the tumorigenicity of Capan-2 cells, implicating a new potential therapeutic target in pancreatic cancer.     

Matuzumab short-term therapy in experimental pancreatic cancer: prolonged antitumor activity in combination with gemcitabine

PURPOSE: The epidermal growth factor receptor ErbB-1 is commonly expressed in pancreatic cancer and ErbB-1 targeting has shown promising results. We wanted to evaluate matuzumab (EMD72000), a fully humanized ErbB-1-specific monoclonal antibody in combination with gemcitabine in experimental pancreatic cancer. EXPERIMENTAL DESIGN: Using the human pancreatic cancer cell line L3.6pl, we investigated matuzumab in vitro and in vivo. ErbB-1 phosphorylation and downstream pathway activation were evaluated by Western blot. Proliferation and migration assays and fluorescence-activated cell sorting analysis were done. For in vivo studies, we used an orthotopic nude mice model in which 40 mg/kg of matuzumab+/-100 mg/kg of gemcitabine were administered twice weekly. Different treatment durations (7, 14, 21, and 25 days) and varying time points of treatment initiation (days 8, 15, 22, and 29) were evaluated. Ki67, CD31, and phosphorylated p44/42 mitogen-activated protein kinase (MAPK) immunohistochemistry were done. RESULTS: ErbB-1 phosphorylation and downstream MAPK and AKT signaling were significantly reduced by matuzumab. Matuzumab significantly inhibited proliferation and migration in vitro, and induced tumor cell apoptosis in a dose-dependant manner. Matuzumab therapy significantly lowered tumor volume in vivo, reduced lymph node and liver metastases, and decreased microvessel density and tumor cell proliferation. These effects were significantly enhanced when gemcitabine was added. A significant and prolonged antitumor activity was even evident with short-term therapy (7 days) and with a late onset of therapy (day 22 after tumor cell injection). CONCLUSIONS: Matuzumab is an effective agent with long-lasting antiproliferative, proapoptotic, antiangiogenic, and antimetastatic activity in human pancreatic cancer models. These effects might be potentiated by gemcitabine.     

Downregulation of nuclear factor-κB p65 subunit by small interfering RNA synergizes with gemcitabine to inhibit the growth of pancreatic cancer

The clinical benefit of gemcitabine for pancreatic cancer is low due to chemoresistance. Nuclear factor (NF)-κB, constitutively activated in pancreatic cancer, is a therapeutic target as it upregulates expression of genes controlling proliferation, apoptosis and angiogenesis. This study aimed to investigate whether downregulation of the p65 subunit of NF-κB by siRNA could enhance the efficacy of gemcitabine to treat pancreatic cancer. p65 siRNA synergized with gemcitabine to inhibit the proliferation and induce the apoptosis of pancreatic cancer cells in vitro and in vivo, and suppress the growth and angiogenesis of pancreatic tumors in nude mice. The mechanisms involved inhibition of NF-κB activity and consequent inhibition of Bcl-2, cyclin D1 and VEGF, and activation of caspase-3. The results suggest that downregulation of NF-κB p65 potentiates the efficacy of gemcitabine in combating pancreatic cancer.     

Enhanced effect of gemcitabine by emodin against pancreatic cancer in vivo via cytochrome C-regulated apoptosis

Gemcitabine is currently the best treatment available for pancreatic cancer, but causes high toxicity. Agents that can enhance the effects of gemcitabine with no or low toxicity are needed for the treatment of pancreatic cancer. Emodin, a natural anthraquinone derivative, is one such agent that has been shown to induce apoptosis in other tumor cells via down-regulation of Bcl-2/Bax and promoting the release of Cytochrome C (CytC), but with very low toxicity. The aim of this study was to evaluate whether emodin can enhance the effect of gemcitabine on pancreatic cancer in?vitro and in?vivo and to investigate the possible mechanisms of the enhancement. In?vitro, emodin inhibited the proliferation of the SW1990 cell line and potentiated the apoptosis induced by gemcitabine, which was demonstrated by activation of caspase-3 in the combination group. In?vivo, tumors from nude mice subcutaneously injected with SW1990 cells and treated with a combination of emodin (40?mg/kg) and gemcitabine (80?mg/kg) showed significant reductions in volume, Ki-67 proliferation index and expression of the Bcl-2/Bax ratio (compared with tumors from mice treated with sodium chloride, emodin alone (40?mg/kg) or gemcitabine alone (125?mg/kg), which induced increasing release of CytC from the mitochondria to the cytoplasm and triggered caspase-3 activation leading to apoptosis. Taken together, our results suggest that emodin improved the anti-tumor effect of gemcitabine, even at a lower dose of gemcitabine which could decrease the toxicity of chemotherapy, on transplanted tumors of the SW1990 cell line through the enhancement of apoptosis induced by gemcitabine, the mechanism of which may be through down-regulation of the Bcl-2/Bax ratio and promoting release of CytC from the mitochondria into the cytoplasm.     

Antitumor activity of erlotinib in combination with gemcitabine in in vitro and in vivo models of KRAS-mutated pancreatic cancers

Erlotinib treatment in combination with gemcitabine is a standard therapy for patients with locally advanced pancreatic cancer in many countries, including the US and the EU. Since mutations of the K-ras oncogene (KRAS) occur in approximately 90% of pancreatic cancers, we examined the antitumor activity of erlotinib in combination with gemcitabine in KRAS-mutated pancreatic cancer cell lines, HPAC and Capan-1, which have the KRAS mutation G12D and G12V, respectively. We analyzed the mode of inhibition of in vitro tumor cell proliferation by means of a combination index and found that a combination treatment of erlotinib plus gemcitabine had an additive effect in the two cell lines. We then examined the effect of erlotinib and gemcitabine on the phosphorylation of epidermal growth factor receptor (EGFR). Erlotinib strongly suppressed, while gemcitabine augmented the phosphorylation of EGFR, which was completely blocked by erlotinib in the two cell lines. An in vivo tumor growth inhibition test was then performed using the HPAC tumor xenograft model. The combination therapy of erlotinib and gemcitabine resulted in a significant inhibition of tumor growth compared with erlotinib or gemcitabine monotherapy. To the best of our knowledge, this is the first study to show the combination effect of erlotinib and gemcitabine in vivo using a xenograft model of a KRAS-mutated pancreatic cancer cell line.     

ROS implication in a new antitumor strategy based on non-thermal plasma

Non-thermal plasma (NTP) is generated by ionizing neutral gas molecules/atoms leading to a highly reactive gas at ambient temperature containing excited molecules, reactive species and generating transient electric fields. Given its potential to interact with tissue or cells without a significant temperature increase, NTP appears as a promising approach for the treatment of various diseases including cancer. The aim of our study was to evaluate the interest of NTP both in vitro and in vivo. To this end, we evaluated the antitumor activity of NTP in vitro on two human cancer cell lines (glioblastoma U87MG and colorectal carcinoma HCT-116). Our data showed that NTP generated a large amount of reactive oxygen species (ROS), leading to the formation of DNA damages. This resulted in a multiphase cell cycle arrest and a subsequent apoptosis induction. In addition, in vivo experiments on U87MG bearing mice showed that NTP induced a reduction of bioluminescence and tumor volume as compared to nontreated mice. An induction of apoptosis was also observed together with an accumulation of cells in S phase of the cell cycle suggesting an arrest of tumor proliferation. In conclusion, we demonstrated here that the potential of NTP to generate ROS renders this strategy particularly promising in the context of tumor treatment.