Ying-Tzu Chang1, Charles C N Wang2, Jiun-Yi Wang3, Tsui-Er Lee4, Yung-Yi Cheng5, Susan L Morris-Natschke6, Kuo-Hsiung Lee7, Chin-Chuan Hung8. 1. Department of Pharmacy, College of Pharmacy, China Medical University, 91 Hsueh-Shih Road, Taichung 40402, Taiwan, ROC. 2. Department of Bioinformatics and Medical Engineering, Asia University. 500, Lioufeng Rd., Wufeng, Taichung 41354, Taiwan, ROC. 3. Department of Healthcare Administration, Asia University, 500, Lioufeng Rd., Wufeng, Taichung 41354, Taiwan, ROC. 4. Office of Physical Education, Asia University, 500, Lioufeng Rd., Wufeng, Taichung 41354, Taiwan, ROC. 5. Natural Products Research Laboratories, UNC Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC 27599, United States.; Department of Medical Research, China Medical University Hospital, China Medical University, Taichung 404, Taiwan, ROC. 6. Natural Products Research Laboratories, UNC Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC 27599, United States. 7. Natural Products Research Laboratories, UNC Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC 27599, United States.; Chinese Medicine Research and Development Center, China Medical University and Hospital, 2 Yude Road, Taichung 40447, Taiwan, ROC. 8. Department of Pharmacy, College of Pharmacy, China Medical University, 91 Hsueh-Shih Road, Taichung 40402, Taiwan, ROC; Department of Pharmacy, China Medical University Hospital, 2 Yude Road, Taichung 40447, Taiwan, ROC. Electronic address: cchung@mail.cmu.edu.tw.
Abstract
BACKGROUND: Multidrug resistance (MDR) in cancer is one of the main obstacles in treatment with chemotherapy. Drug efflux through P-glycoprotein is the major mechanism involved in MDR. A potential strategy to provide the best possible clinical outcomes is to develop P-glycoprotein (P-gp) inhibitors from natural products. PURPOSE: The present study investigated the effects of the natural sesquiterpene lactone tenulin and its derivative isotenulin on human P-gp; the mechanisms of kinetic interactions were also explored. METHODS: The human P-gp (ABCB1/Flp-In™-293) stable expression cells were established by using the Flp-In™ system. The effects of tenulin and isotenulin on cell viability were evaluated by SRB assays in established cell lines, sensitive cancer cell line (HeLaS3), and resistant cancer cell line (KB-vin). The transporter inhibition ability was evaluated by calcein-AM uptake assays. The P-gp inhibition kinetics of tenulin and isotenulin were evaluated by rhodamine123 and doxorubicin efflux assays. The ATPase activity was evaluated with the Pgp-Glo™ Assay System. RESULTS: Tenulin and isotenulin significantly inhibited the P-gp efflux function by stimulating P-gp ATPase activity. Tenulin and isotenulin interacted with the effluxes of rhodamine 123 and doxorubicin through a competitive and noncompetitive mechanism, respectively. The combinations of tenulin and isotenulin with chemotherapeutic drugs significantly resensitized MDR cancer cells. CONCLUSION: These results suggested that tenulin and isotenulin are potential candidates to be developed for synergistic treatment of MDR cancers.
BACKGROUND: Multidrug resistance (MDR) in cancer is one of the main obstacles in treatment with chemotherapy. Drug efflux through P-glycoprotein is the major mechanism involved in MDR. A potential strategy to provide the best possible clinical outcomes is to develop P-glycoprotein (P-gp) inhibitors from natural products. PURPOSE: The present study investigated the effects of the natural sesquiterpene lactone tenulin and its derivative isotenulin on humanP-gp; the mechanisms of kinetic interactions were also explored. METHODS: The humanP-gp (ABCB1/Flp-In™-293) stable expression cells were established by using the Flp-In™ system. The effects of tenulin and isotenulin on cell viability were evaluated by SRB assays in established cell lines, sensitive cancer cell line (HeLaS3), and resistant cancer cell line (KB-vin). The transporter inhibition ability was evaluated by calcein-AM uptake assays. The P-gp inhibition kinetics of tenulin and isotenulin were evaluated by rhodamine123 and doxorubicin efflux assays. The ATPase activity was evaluated with the Pgp-Glo™ Assay System. RESULTS: Tenulin and isotenulin significantly inhibited the P-gp efflux function by stimulating P-gpATPase activity. Tenulin and isotenulin interacted with the effluxes of rhodamine 123 and doxorubicin through a competitive and noncompetitive mechanism, respectively. The combinations of tenulin and isotenulin with chemotherapeutic drugs significantly resensitized MDR cancer cells. CONCLUSION: These results suggested that tenulin and isotenulin are potential candidates to be developed for synergistic treatment of MDR cancers.