ABSTRACT: Pancreatic cancer is an aggressive malignancy, which generally develops resistance to chemotherapy. Agents that are safe and can sensitize cancer to chemotherapy are urgently needed. Escin, a natural mixture of triterpene saponins isolated from Aesculus wilsonii Rehd, has been demonstrated to possess anti-cancer activity both in vitro and in vivo. The anti-cancer activity of escin could be, in part, due to the inactivation of nuclear factor-κB (NF-κB). In contrast, chemotherapy including gemcitabine could activate NF-κB and lead to chemoresistance. Here, for the first time, we investigated whether escin, via the inactivation of NF-κB, would potentiate the antitumor activity of gemcitabine in pancreatic cancer.
Cell viability and proliferation, apoptosis, NF-κB activity and the expression of NF-κB-linked genes were all examined in vitro. The antitumor effect of escin with or without gemcitabine in pancreatic cancer was also assessed using BxPC-3 xenografts subcutaneously established in BALB/c nude mice.
Escin not only potentiated the proliferation-inhibiting and apoptosis-inducing effect of gemcitabine in both BxPC-3 and PANC-1 cell lines in vitro, but also dramatically enhanced its suppressive effect on tumor growth in nude mice. The mechanism is at least partially due to the inhibition of NF-κB activity and consequent inhibition of c-Myc, COX-2, Cyclin D1, Survivin, Bcl-2 and Bcl-xL, and the activation of caspase-3.
These data suggest that escin, via inactivation of NF-κB, could potentiate the efficacy of gemcitabine in combating pancreatic cancer, which could be a novel and potentially important therapeutic approach for the treatment for pancreatic cancer.
Journal of Cancer Research and Clinical Oncology 01/2012; 138(5):785-97. · 2.56 Impact Factor
ABSTRACT: Dihydroartemisinin (DHA), a semi-synthetic derivative of artemisinin, has recently shown antitumor activity in various cancer cells. Apo2 ligand or tumor necrosis factor-related apoptosis-inducing ligand (Apo2L/TRAIL) is regarded as a promising anticancer agent, but chemoresistance affects its efficacy as a treatment strategy. Apoptosis induced by the combination of DHA and Apo2L/TRAIL has not been well documented, and the mechanisms involved remain unclear.
Here, we report that DHA enhances the efficacy of Apo2L/TRAIL for the treatment of pancreatic cancer. We found that combined therapy using DHA and Apo2L/TRAIL significantly enhanced apoptosis in BxPC-3 and PANC-1 cells compared with single-agent treatment in vitro. The effect of DHA was mediated through the generation of reactive oxygen species, the induction of death receptor 5 (DR5) and the modulation of apoptosis-related proteins. However, N-acetyl cysteine significantly reduced the enhanced apoptosis observed with the combination of DHA and Apo2L/TRAIL. In addition, knockdown of DR5 by small interfering RNA also significantly reduced the amount of apoptosis induced by DHA and Apo2L/TRAIL.
These results suggest that DHA enhances Apo2L/TRAIL-mediated apoptosis in human pancreatic cancer cells through reactive oxygen species-mediated up-regulation of DR5.
PLoS ONE 01/2012; 7(5):e37222. · 4.09 Impact Factor
ABSTRACT: Epithelial to mesenchymal transition (EMT) induced by hypoxia is one of the critical causes of treatment failure in different types of human cancers. NF-κB is closely involved in the progression of EMT. Compared with HIF-1α, the correlation between NF-κB and EMT during hypoxia has been less studied, and although the phenomenon was observed in the past, the molecular mechanisms involved remained unclear.
Here, we report that hypoxia or overexpression of hypoxia-inducible factor-1α (HIF-1α) promotes EMT in pancreatic cancer cells. On molecular or pharmacologic inhibition of NF-κB, hypoxic cells regained expression of E-cadherin, lost expression of N-cadherin, and attenuated their highly invasive and drug-resistant phenotype. Introducing a pcDNA3.0/HIF-1α into pancreatic cancer cells under normoxic conditions heightened NF-κB activity, phenocopying EMT effects produced by hypoxia. Conversely, inhibiting the heightened NF-κB activity in this setting attenuated the EMT phenotype.
These results suggest that hypoxia or overexpression of HIF-1α induces the EMT that is largely dependent on NF-κB in pancreatic cancer cells.
PLoS ONE 01/2011; 6(8):e23752. · 4.09 Impact Factor