ABSTRACT
BACKGROUND: Pancreatic cancer, associated with poor prognosis and low survival rate, has been the fourth leading cause of cancer-related death in the US. Although gemcitabine (Gem) is the first-line chemotherapeutic drug in the management of pancreatic cancer, the median survival extension is only 1.5 months, indicating unsatisfactory clinical results. Therefore, exploring agents that can enhance the anti-cancer activity of Gem would be an attractive strategy. PURPOSE: Our previous studies have demonstrated that eriocalyxin b (EriB), an entkaurane diterpenoid isolated from Isodon eriocalyx (Dunn.) Hara, possesses anti-pancreatic cancer effects, thus acting as a potential therapeutic agent. In this study, we further investigated whether EriB or the ethanol extract of I. eriocalyx (Isodon) could potentiate the cytotoxic activity of Gem in human pancreatic adenocarcinoma cells. In addition, the mechanism associated with their effects was also studied. METHODS: The anti-proliferation effect was assessed by MTT assay and Ki-67 immunostaining. The combination effect (addition, synergism and antagonism) of various agents was calculated by the Calcusyn software (Biosoft), utilizing the T.C. Chou Method. Apoptosis was detected using Annexin V and PI double staining followed by quantitative flow cytometry. Protein expression regulated by various treatments was analyzed by western blotting. RESULTS: The combination index revealed that Gem and EriB (or Isodon extract) had synergistic anti-proliferative effect. Both cellular apoptotic and anti-proliferative effects of Gem were significantly increased after combination with EriB (or Isodon extract). The underlying mechanisms involved in the combination effects were elucidated, which include: (1) increased activation of the caspase cascade; (2) reduction of PDK1 and AKT phosphorylation; (3) induction of JNK phosphorylation by Isodon and Gem combination. CONCLUSION: Gem and EriB (or Isodon extract) taken together in combination regulated PDK1/AKT1/caspase and JNK signaling and promoted apoptosis synergistically, which may contribute to the much increased anti-proliferative activity compared to either agent alone.
Subject(s)
Antineoplastic Combined Chemotherapy Protocols/pharmacology , Diterpenes/pharmacology , Isodon/chemistry , Pancreatic Neoplasms/drug therapy , Adenocarcinoma/drug therapy , Adenocarcinoma/pathology , Antineoplastic Agents, Phytogenic/administration & dosage , Antineoplastic Agents, Phytogenic/pharmacology , Apoptosis/drug effects , Caspases/metabolism , Cell Line, Tumor , Deoxycytidine/administration & dosage , Deoxycytidine/analogs & derivatives , Diterpenes/administration & dosage , Humans , MAP Kinase Signaling System , Pancreatic Neoplasms/pathology , Phosphorylation/drug effects , Plant Extracts/pharmacology , Protein Serine-Threonine Kinases/metabolism , Proto-Oncogene Proteins c-akt/metabolism , Pyruvate Dehydrogenase Acetyl-Transferring Kinase , GemcitabineABSTRACT
Thiol-containing antioxidant systems play an important role in regulating cellular redox homeostasis. Several anti-cancer agents act by targeting these systems by inducing the production of reactive oxygen species (ROS). Our earlier studies have shown that Eriocalyxin B (EriB), a diterpenoid isolated from Isodon eriocalyx, possesses anti-pancreatic tumour activities in vitro and in vivo. The present study further demonstrated that only thiol-containing antioxidants, N-acetylcysteine (NAC) or dithiothreitol (DTT), inhibited EriB-induced cytotoxicity and apoptosis. EriB suppressed the glutathione and thioredoxin antioxidant systems, thus increasing the intracellular ROS levels and regulating the MAPK, NFκB pathways. Treatment with EriB depleted the intracellular thiol-containing proteins in CAPAN-2 cells. In vivo studies also showed that EriB treatment (2.5 mg/kg) reduced the pancreatic tumour weights significantly in nude mice with increased superoxide levels. Taken together, our results shed important new light on the molecular mechanisms of EriB acting as an apoptogenic agent and its therapeutic potential for pancreatic cancer.
Subject(s)
Antioxidants/metabolism , Apoptosis/drug effects , Diterpenes/pharmacology , Diterpenes/therapeutic use , Pancreatic Neoplasms/drug therapy , Pancreatic Neoplasms/metabolism , Signal Transduction/drug effects , Animals , Cell Line, Tumor , Glutathione/metabolism , Humans , Male , Mice , Mice, Nude , Reactive Oxygen Species/metabolism , Pancreatic NeoplasmsABSTRACT
A new method for detection of the soild/soild interface wave with laser ultrasonics is introduced in this paper. Based on the interaction between the acoustic wave and the probe laser beam of an interferometer in a transparent solid, the Stoneley waves propagated along the quartz/steel interface are detected successfully. The dispersion properties of Leaky Rayleigh wave are studied when the boundary conditions are described by interface spring mode. The Leaky Rayleigh wave at Plexiglas/aluminum interface is also detected and the experimental results are in good agreement with the theoretical results. It shows that the interface wave should be a powerful technique for evaluation of the interface properties.
ABSTRACT
Two new coumarins (1) and (2), along with seven known coumarins 3-9, were isolated from the leaves and stems of Coriarianepalensis Wall. The two new compounds were established as 7-hydroxy-6-methoxy-3,8-bis(3-methyl-2-butenyl) coumarin (1) and 7-hydroxy-6-methoxy-3-(3-methyl-2-butenyl) coumarin (2), on the basis of 1D and 2D NMR techniques. The known compounds 3, 6-9 were isolated from this plant for the first time.
Subject(s)
Coumarins/chemistry , Coumarins/isolation & purification , Magnoliopsida/chemistry , Molecular Structure , Plant Leaves/chemistry , Plant Stems/chemistryABSTRACT
The isolation of griffonilide (1), lithospermoside (2) and magnoflorine (3) from the roots of Semiaquilegia adoxoides is reported.
