Yanmei Lou1, Zhenzhen Guo1, Yuanfeng Zhu1, Guiyu Zhang1, Ying Wang2, Xiaoxiao Qi3, Linlin Lu4, Zhongqiu Liu5, Jinjun Wu6. 1. Joint Laboratory for Translational Cancer Research of Chinese Medicine of the Ministry of Education of the People's Republic of China, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510006, China. 2. Joint Laboratory for Translational Cancer Research of Chinese Medicine of the Ministry of Education of the People's Republic of China, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510006, China. Electronic address: wangy@gzucm.edu.cn. 3. Joint Laboratory for Translational Cancer Research of Chinese Medicine of the Ministry of Education of the People's Republic of China, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510006, China. Electronic address: qixiaoxiao@gzucm.edu.cn. 4. Joint Laboratory for Translational Cancer Research of Chinese Medicine of the Ministry of Education of the People's Republic of China, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510006, China; State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Macau. Electronic address: lllu@gzucm.edu.cn. 5. Joint Laboratory for Translational Cancer Research of Chinese Medicine of the Ministry of Education of the People's Republic of China, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510006, China; State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Macau. Electronic address: liuzq@gzucm.edu.cn. 6. Joint Laboratory for Translational Cancer Research of Chinese Medicine of the Ministry of Education of the People's Republic of China, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510006, China. Electronic address: wujinjun@gzucm.edu.cn.
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE: Astragali radix (Huang Qi, HQ), a well-known Chinese herbal medicine, is widely coadministered with many other drugs for treating diseases. The potential herb-drug interactions (HDIs) possibly occur during the combination therapy. P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) are the crucial targets that mediate the production of HDIs. We previously observed that HQ and its three main bioactive compounds, including Astragaloside IV (AS-IV), calycosin (CS) and formononetin (FMNT), could significantly induce the expression of P-gp and BCRP in HepG2 cells in vitro. However, their modulations on the function of P-gp and BCRP remain unknown; their impact on these two proteins expression in vivo is not clear; the exact regulatory mechanism has also not yet been explored. AIM OF THE STUDY: This study aimed to investigate the impact of HQ, AS-IV, CS and FMNT on P-gp and BCRP in vivo, and the exact regulatory mechanism involved. The effects of HQ and these compounds on the function of P-gp and BCRP were also studied. MATERIALS AND METHODS: Wild-type C57BL/6 mice and nuclear factor E2-related factor-2 knockout (Nrf2-/-) C57BL/6 mice were orally treated with HQ, AS-IV, CS or FMNT. The protein levels of P-gp and BCRP in the liver of mice were measured by using Western blot and immunohistochemistry. The mRNA levels were measured by using real-time PCR. The activation of the drugs on the antioxidant response element (ARE)-luciferin activity was studied by using reporter assay in a stably transfected HepG2-C8 cells. The efflux activity of P-gp and BCRP in HepG2 cells were tested by using flow cytometer with typical probes. RESULTS: HQ, AS-IV, CS and FMNT significantly upregulated the P-gp and BCRP expression in the liver of wild-type mice. The induction was significantly reversed in the Nrf2-/- mice. HQ and these compounds significantly increased the Nrf2 expression in wild-type mice. HQ and these compounds also markedly enhanced the ARE-luciferin activity and promoted the nuclear translocation of Nrf2 in cells. Besides, HQ and these compounds significantly enhanced the efflux activity of P-gp and BCRP, and increased the intracellular ATP levels. CONCLUSIONS: Our results proved that HQ and its main bioactive compounds could induce the P-gp and BCRP expression through the activation of the Nrf2-mediated signaling pathway. HQ and these compounds also significantly enhanced the efflux activity of P-gp and BCRP, and the increased intracellular ATP levels were likely involved in the increased P-gp and BCRP function. These results suggested that potentially HDIs likely occurred when HQ was used concomitantly with other drugs that are substrates of P-gp and BCRP.
ETHNOPHARMACOLOGICAL RELEVANCE: Astragali radix (Huang Qi, HQ), a well-known Chinese herbal medicine, is widely coadministered with many other drugs for treating diseases. The potential herb-drug interactions (HDIs) possibly occur during the combination therapy. P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) are the crucial targets that mediate the production of HDIs. We previously observed that HQ and its three main bioactive compounds, including Astragaloside IV (AS-IV), calycosin (CS) and formononetin (FMNT), could significantly induce the expression of P-gp and BCRP in HepG2 cells in vitro. However, their modulations on the function of P-gp and BCRP remain unknown; their impact on these two proteins expression in vivo is not clear; the exact regulatory mechanism has also not yet been explored. AIM OF THE STUDY: This study aimed to investigate the impact of HQ, AS-IV, CS and FMNT on P-gp and BCRP in vivo, and the exact regulatory mechanism involved. The effects of HQ and these compounds on the function of P-gp and BCRP were also studied. MATERIALS AND METHODS: Wild-type C57BL/6 mice and nuclear factor E2-related factor-2 knockout (Nrf2-/-) C57BL/6 mice were orally treated with HQ, AS-IV, CS or FMNT. The protein levels of P-gp and BCRP in the liver of mice were measured by using Western blot and immunohistochemistry. The mRNA levels were measured by using real-time PCR. The activation of the drugs on the antioxidant response element (ARE)-luciferin activity was studied by using reporter assay in a stably transfected HepG2-C8 cells. The efflux activity of P-gp and BCRP in HepG2 cells were tested by using flow cytometer with typical probes. RESULTS: HQ, AS-IV, CS and FMNT significantly upregulated the P-gp and BCRP expression in the liver of wild-type mice. The induction was significantly reversed in the Nrf2-/- mice. HQ and these compounds significantly increased the Nrf2 expression in wild-type mice. HQ and these compounds also markedly enhanced the ARE-luciferin activity and promoted the nuclear translocation of Nrf2 in cells. Besides, HQ and these compounds significantly enhanced the efflux activity of P-gp and BCRP, and increased the intracellular ATP levels. CONCLUSIONS: Our results proved that HQ and its main bioactive compounds could induce the P-gp and BCRP expression through the activation of the Nrf2-mediated signaling pathway. HQ and these compounds also significantly enhanced the efflux activity of P-gp and BCRP, and the increased intracellular ATP levels were likely involved in the increased P-gp and BCRP function. These results suggested that potentially HDIs likely occurred when HQ was used concomitantly with other drugs that are substrates of P-gp and BCRP.
Keywords:
Astragali radix; Astragaloside IV; Calycosin; Formononetin; Nuclear factor E2-related factor-2; P-glycoprotein and breast cancer resistance protein