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.

Emodin reverses gemcitabine resistance in pancreatic cancer cells via the mitochondrial apoptosis pathway in vitro.

Gemcitabine resistance is a common problem of pancreatic cancer chemotherapy, and how to reverse it plays an important role in the treatment of pancreatic cancer. This study investigated the effect of emodin on the gemcitabine-resistant pancreatic cancer cell line SW1990/Gem, and explored the potential mechanism of its action. SW1990/Gem was obtained by culture of the pancreatic cancer cell line SW1990 in vitro by intermittently increasing the concentration of gemcitabine in the culture medium for 10 months, observing the morphology using inverted microscopy. SW1990/Gem cells were pretreated with emodin (10 µM) for different periods followed by treatment with gemcitabine (20 µM) for 48 h; cell proliferation was tested by MTT assay. SW1990/Gem cells were treated by emodin with different concentrations for 48 h, cell apoptosis was detected by flow cytometry (FCM). The expression of gene and protein, such as MDR-1 (P-gp), NF-κB, Bcl-2, Bax, cytochrome-C (cytosol), caspase-9 and -3 were measured by RT-PCR and Western blotting. The function of P-gp in SW1990/Gem cells was checked by FCM. The results showed that the SW1990/Gem cells changed greatly in morphology and the resistance index was 48.63. Emodin promoted cell apoptosis of the gemcitabine-resistant cell line SW1990/Gem in a dose-dependent manner. Emodin enhanced the SW1990/Gem cell sensitivity to gemcitabine in a time-dependent manner. Emodin monotherapy or combination with gemcitabine both decreased the gene and protein expression levels of MDR-1 (P-gp), NF-κB and Bcl-2 and inhibited the function of P-gp, but increased the expression levels of Bax, cytochrome-C (cytosol), caspase-9 and -3, and promoted cell apoptosis. This demonstrated that emodin had a reversing effect on the gemcitabine-resistant cell line SW1990/Gem, possibly via decreasing the function of P-gp and activating the mitochondrial apoptosis pathway in vitro.

Enhanced antitumor efficacy of gemcitabine by evodiamine on pancreatic cancer via regulating PI3K/Akt pathway.

Evodiamine has therapeutic potential against cancers. This study was designed to investigate whether combination therapy with gemcitabine and evodiamine enhanced antitumor efficacy in pancreatic cancer. In vitro application of the combination therapy triggered significantly higher frequency of pancreatic cancer cells apoptosis, inhibited the activities of PI3K, Akt, PKA, mTOR and PTEN, and decreased the activation of NF-κB and expression of NF-κB-regulated products. In vivo application of the combination therapy induced significant enhancement of tumor cell apoptosis, reductions in tumor volume, and inhibited activation of mTOR and PTEN. In conclusion, evodiamine can augment the therapeutic effect of gemcitabine in pancreatic cancer through direct or indirect negative regulation of the PI3K/Akt pathway.

Antitumor activity of emodin against pancreatic cancer depends on its dual role: promotion of apoptosis and suppression of angiogenesis.

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.

Emodin induces Panc-1 cell apoptosis via declining the mitochondrial membrane potential.

In this study, we investigated the apoptotic effect of emodin on human pancreatic cancer cell line Panc-1 in vitro and in vivo as well as the possible mechanisms involved. In vitro, human pancreatic cancer cell line Panc-1 was exposed to varying concentrations of emodin (0, 10, 20, 40 or 80 µmol/l). Then the mitochondrial membrane potential (MMP) was analyzed by JC-1 staining, cell apoptosis was analyzed by flow cytometry (FCM) and cell proliferation was analyzed by MTT. In vivo, nude mice orthotopically implanted were randomly divided into five groups to receive treatments by different doses of emodin: control group (normal saline 0.2 ml), E10 group (emodin 10 mg/kg), E20 group (emodin 20 mg/kg), E40 group (emodin 40 mg/kg) and E80 group (emodin 80 mg/kg). Each mouse was treated 5 times by intraperitoneal injection of emodin every 3 days. During the treatment, the feeding stuff was recorded. One week after the last treatment, we recorded the body weight and the maximum diameter of tumor in each group before the mice were sacrificed. Then the cell apoptosis of the tumor was tested by TUNEL assay. The results in vitro showed that the MMP of the cells declined and the apoptosis rate increased with the emodin concentration increasing and the cell proliferation of each group was inhibited in a dose- and time-dependent manner by emodin. The feeding stuff curve did not decline significantly in E40 group and the apoptosis rate of the tumor cells in this group was higher than the lower-dose groups. Taken together, our results demonstrate that emodin may induce the pancreatic cancer cell apoptosis via declining the MMP and a moderate dose of emodin improved the living state of the model mice.

Emodin potentiates the antitumor effects of gemcitabine in PANC-1 pancreatic cancer xenograft model in vivo via inhibition of inhibitors of apoptosis.

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.

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.

Antitumor and apoptosis-promoting properties of emodin, an anthraquinone derivative from Rheum officinale Baill, against pancreatic cancer in mice via inhibition of Akt activation.

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.