P-glycoprotein-mediated herb-drug interaction evaluation between Tenacissoside G and paclitaxel.

P-glycoprotein (P-gp)-mediated herb-drug interactions (HDIs) may impact drug efficacy and safety. Tenacissoside G (Tsd-G), a major active component of Marsdenia tenacissima, exhibits anticancer activity. To analyze the effect of Tsd-G on the pharmacokinetics of paclitaxel (PTX), researchers selected 30 Sprague-Dawley (SD) rats, randomized into a solvent control group, a verapamil positive control group, and 20, 40, and 60 mg/kg Tsd-G groups. After seven consecutive days of intraperitoneal injection of verapamil or Tsd-G, a single dose of 6 mg/kg PTX was injected intravenously. Plasma samples were collected at different time points, and proteins were precipitated using a methanol-acetonitrile solution. An ultrahigh-performance liquid chromatography-tandem mass spectrometry method was developed, with docetaxel as an internal standard, and quantified using positive ion multiple reaction monitoring (MRM) mode. This analytical method's specificity, accuracy, precision, recovery, matrix effect, and sample stability meet the requirements for biological sample determination. After Tsd-G administration in rats, the mean residence time of PTX was significantly prolonged. And Tsd-G can stably bind to P-gp by forming hydrogen bonds and inhibiting the expression of P-gp in rat liver. Although the metabolites of PTX were not detected in this study, the above results still indicate the existence of HDIs between Tsd-G and PTX, and P-gp may be the main target to mediate HDIs.

Tongguanteng injection reverses paclitaxel resistance via upregulation of TAB1 expression in ovarian cancer in vitro and in vivo.

ETHNOPHARMACOLOGICAL RELEVANCE: Tongguanteng injection (TGT), the water extract from the stem of the Traditional Chinese hebal medicine of Marsdenia tenacissima (Roxb.) Wight et Arn. has been used as anticancer remedy for decades. TGT was not only used in the treatment of many malignant cancers extensively, but also an adjuvant anticancer drug with chemotherapeutics clinically. AIM OF THE STUDY: To evaluate the effects of TGT on reversing paclitaxel (PTX) resistance and investigate the potential mechanism related to TAB1 in ovarian cancer (OC) in vitro and in vivo. MATERIALS AND METHODS: The synergistic effect and reversal ratio were determined by CCK8 assay and median-effect principle after the combination of TGT and PTX in OC A2780 and its PTX-resistant (A2780/T) cells. The biological functions in cell apoptosis, migration and invasion of A2780/T cells treated by PTX 4 µM with TGT 20, 40, 80 mg⋅mL-1 for 24 h were evaluated by colony formation, flow cytometry, wound healing and transwell assays. Proteomics technique and bioinformatic analysis were used to indentify the change of TAB1 expression in A2780/T cells induced by TGT. The association between TAB1 expression and human OC was analyzed by gene expression databases. In A2780/T cells, western blotting and colony formation assays were used to investigate the relationship between TAB1 expression and PTX resistance after TAB1 overexpression by TAB1 plasmids. The mechanism of TGT and PTX regulating TAB1 and its related proteins were explored by western blotting and flow cytometry assays after TAB1 knock-down using siTAB1. Moreover, TUNEL staining, immunohistochemistry (IHC) and histopathology were used to observe the antitumor effects, TAB1 and p-p38 expression and the tissues impairments in nude mice xenograft model established by A2780/T cells after the co-treatment with TGT and PTX by in vivo. RESULTS: TGT combined with PTX showed the synergistic effect (CI<1), which could reverse the IC50 values of PTX in OC A2780 and A2780/T cells about 23.50 and 6.44 times, respectively. Besides, TGT combined with PTX could significantly inhibit the migration, invasion and promote apoptosis of A2780/T cells. We identified that TGT could induce TAB1 expression in A2780/T cells by proteomics analysis. TAB1 downregulation was significantly associated with tumorigenesis and poor prognosis in OC patients and PTX resistance in A2780/T cells. Furthermore, TGT could activate TAB1/TAK1/p38 MAPK signaling pathway targeting TAB1 and regulate the expression of Bax, Bcl-2 proteins to improve the sensitivity of A2780/T cells to PTX. TGT combined with PTX also showed a greater inhibition in tumor growth than PTX monotherapy in vivo. These promising results show the efficacy of TGT in reversing PTX resistance and provide a potential strategy that targeting TAB1/TAK1/p38 MAPK signaling pathway may improve the chemotherapy sensitivity in OC. CONCLUSIONS: Our results revealed that Tongguanteng injection could reverse paclitaxel resistance and the potential mechanism might be associated with the activation of TAB1/TAK1/p38 MAPK signaling pathway in OC in vitro and in vivo. TAB1 might be a pivotal target for reversing PTX resistance. This study will provide a theoretical basis for the combination of Tongguanteng injection and paclitaxel in clinic.

Xiaoaiping injection enhances paclitaxel efficacy in ovarian cancer via pregnane X receptor and its downstream molecules.

ETHNOPHARMACOLOGICAL RELEVANCE: Xiaoaiping injection, a traditional Chinese medical injection extracted from root of Marsdenia tenacissima (Roxb.) Moon, has been exclusively used on curing malignant tumor in China and as adjuvant therapeutic agent for chemotherapeutics, including paclitaxel. AIM OF THE STUDY: The goal of this study was to investigate the synergistic inhibitory efficacy of Xiaoaiping injection and paclitaxel on ovarian cancer. The mechanism may be associated with nuclear receptor pregnane X receptor (PXR) regulating its downstream molecules. MATERIALS AND METHODS: In vitro, MTT assay, flow cytometry and Hoechst dyeing were used to evaluate the SK-OV-3 cell proliferation, apoptosis and cell cycle respectively. The mRNA and protein expression of PXR and its downstream CYP450 enzymes, transporters and Bcl-2 families were measured by qRT-PCR and Western blot. Rhodamine 123 efflux experiment was conducted to detect the P-gp efflux ability. PXR plasmid and PXR siRNA were transiently transfected into SK-OV-3 cells respectively to establish PXR-overexpressed or PXR-interfered cells. In vivo, xenograft tumor mice model was established by SK-OV-3 cells to estimate the antitumor effect of Xiaoaiping injection combined with paclitaxel. The expressions of PXR and its downstream molecules in tumor tissues were determined to further clarify the potential mechanism. RESULTS: Xiaoaiping injection significantly enhanced the anti-proliferation, pro-apoptosis effect of paclitaxel on SK-OV-3 cells. The synergetic effect was displayed by Xiaoaiping injection inhibiting paclitaxel-induced PXR and CAR expression, which subsequently inhibited CYP450 enzymes CYP2C8 and CYP3A4, transporter P-gp and anti-apoptotic proteins Bcl-2 and Bcl-xl in SK-OV-3 cells. In PXR-overexpressed cells, Xiaoaiping injection down-regulated the expression of PXR and its downstream molecules. The result of xenograft tumor model showed that Xiaoaiping injection combined with paclitaxel enhanced anti-tumor effect on ovarian cancer in vivo. CONCLUSIONS: Xiaoaiping injection enhances anti-tumor effect of paclitaxel by inhibiting cell proliferation, inducing apoptosis process. The mechanism may be associated with Xiaoaiping injection inhibiting PXR and its downstream metabolic enzymes CYP2C8, CYP3A4, transporter P-gp and anti-apoptosis protein Bcl-2.

Xiao-Ai-Ping Injection Enhances Effect of Paclitaxel to Suppress Breast Cancer Proliferation and Metastasis via Activating Transcription Factor 3.

Chemotherapy is an effective treatment for invasive breast cancer. Paradoxically, many recently published findings showed that the first-line chemotherapeutic agent paclitaxel (PTX) showed pro-metastatic effects in the progress of treating breast cancer. Xiao-Ai-Ping (XAP) injection, composed of a traditional herbal medicine, Marsdenia tenacissimae extract, is known to exert antitumor effects on various cancers. However, there are few experimental studies on breast cancer. The underlying mechanism of the antitumor effect of XAP combined with chemotherapy agents has not been fully understood. In the present study, we sought to find the antitumor effects of XAP combined with PTX in vitro and in vivo. The data demonstrated that the combination of XAP with PTX resulted in remarkable enhancement of the pro-apoptotic, migration-inhibiting, and anti-invasive effects of PTX in vitro. Significantly, further study showed the overexpression of ATF3 in PTX-treated cell, while XAP counteracted the change of ATF3 induced by PTX. Moreover, it showed that combination treatment could promote the inhibition of tumor growth in MDA-MB-231 cell xenograft mouse model. Compared with PTX treatment, the downregulation of ATF3 indicated that ATF3 played a pivotal role in the combination of XAP with PTX to exert a synergistic effect. Overall, it is expected that PTX combined with XAP may serve as an effective agent for antitumor treatment, and dampening ATF3 maybe a potential strategy to improve the efficacy of PTX.

Effect of Xiao-Ai-Ping injection on paclitaxel pharmacokinetics in rats by LC-MS/MS method.

Xiao-Ai-Ping injection (XAP) has been shown to be clinically effective in treatment of gastric carcinoma, liver cancer and lung cancer, when it was combined with anticancer drug paclitaxel (PTX). To analyze the effect of XAP on the pharmacokinetics of PTX, a liquid chromatography-tandem mass spectroscopy (LCMS/MS) assay method was developed and validated to quantify PTX simultaneously and its main metabolite 3'-p-hydroxypaclitaxel (C3'-OHP) in rat plasma. PTX and C3'-OHP were quantified using positive MRM mode. The analysis method was validated for specificity, recovery, carry-over, accuracy, precision, sample stability and dilution integrity under various storage conditions. The pharmacokinetic parameters were determined in rats after tail intravenous administration of 6 mg/mL PTX in the absence (control group) or presence of intraperitoneal administration of 10 mL/kg、20 mL/kg XAP (study groups). Compared to control group, the area under the plasma concentration-time curve (AUC) of PTX and C3'-OHP in study groups increased significantly following consecutive administration with XAP for 10 days. In conclusion, pretreatment with XAP enhanced the exposure of PTX and C3'-OHP. There would be herb-drug interaction happening between XAP and PTX in rats.

Effects of Danhong injection, a traditional Chinese medicine, on nine cytochrome P450 isoforms in vitro.

Danhong injection (DHI) is made from Salvia miltiorrhiza Bunge. and Carthamus tinctorius L. extract and is widely used in the clinical treatment of cardiovascular and cerebrovascular diseases. This study aimed to evaluate the effect of DHI on cytochrome P450 (CYP450) enzymes in vitro to predict drug-drug interactions based on CYP450 as combination therapy. To assess the inhibitory effect of DHI on CYP450, we detected the IC50 value of DHI on CYP450 in vitro by liquid chromatography/tandem mass spectrometry (LC-MS/MS). Simultaneously, the induction effect of DHI on CYP450s was also evaluated. The relative induction ratios of DHI on CYP1A2, CYP2B6 and CYP3A4 activity were calculated by LC-MS/MS. The expression level of CYP3A4 mRNA was determined by reverse transcription PCR (RT-PCR). The LC-MS/MS data showed DHI intensively inhibit CYP2A6 activity and the intensity of inhibition was followed by CYP2C8, CYP3A4, CYP2C19, CYP2B6, CYP2D6, CYP1A2, CYP2E1 and CYP2C9 in vitro. The results of RT-PCR showed that there is a certain induction of DHI on CYP3A4 mRNA in human primary hepatocytes in vitro. The study suggested that drug-drug interactions might occur in clinical co-administration of drugs owing to the CYP2A6 inhibition and CYP3A4 induction.

Effects of diosmetin on nine cytochrome P450 isoforms, UGTs and three drug transporters in vitro.

Diosmetin (3', 5, 7-trihydroxy-4'-methoxyflavone), a natural flavonoid from traditional Chinese herbs, has been used in various medicinal products because of its anticancer, antimicrobial, antioxidant, estrogenic and anti-inflammatory activity. However, flavonoids could affect the metabolic enzymes and cause drug-drug interactions (DDI), reducing the efficacy of co-administered drugs and potentially resulting in serious adverse reactions. To evaluate its potential to interact with co-administered drugs, the IC50 value of phase I cytochrome P450 enzymes (CYPs), phase II UDP-glucuronyltransferases (UGTs) and hepatic uptake transporters (organic cation transporters (OCTs), organic anion transporter polypeptides (OATPs) and Na+-taurocholate cotransporting polypeptides (NTCPs)) were examined in vitro by LC-MS/MS. Diosmetin showed strong inhibition of CYP1A2 in a concentration-dependent manner. The intensity of the inhibitory effect was followed by CYP2C8, CYP2C9, CYP2C19 and CYP2E1. For CYP2A6, CYP2B6, CYP2D6 and CYP3A4, diosmetin was found to have no significant inhibitory effects, and the induction effect on CYPs was not significant. For UGTs, diosmetin had a minimal inhibitory effect. In addition, the inhibitory effects of diosmetin on OATP and OCT1 were weak, and it had little effect on NTCP. This finding indicated that drug-drug interactions induced by diosmetin may occur through co-administration of drugs metabolized by CYP1A2.

Identification of natural products as modulators of OATP2B1 using LC-MS/MS to quantify OATP-mediated uptake.

CONTEXT: Organic anion-transporting polypeptide 2B1 (OATP2B1) which is highly expressed in enterocytes and hepatocytes could be a key determinant for the intestinal absorption and hepatic uptake of its substrate drugs. Natural products are commonly used in traditional Chinese medicine, foods, and beverages. OBJECTIVE: The objective of this study is to determine the OATP2B1-mediated drug interactions that could occur between natural products and OATP2B1 substrate drugs. MATERIALS AND METHODS: Human OATP2B1 was transiently expressed in human embryonic kidney (HEK293) cells and characterized by immunofluorescence, Western blot, and uptake assay. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods for detecting OATP2B1 substrates estrone-3-sulfate (E3S) and three statins had been developed and were employed to investigate the effects of 27 frequently used natural products on the function of OATP2B1. Uptake of 5 µM E3S and 1 µM statins in the absence or presence of natural products was measured at 37 °C for 2 min with empty vector- and OATP2B1-transfected HEK293 cells. The IC50 values of inhibitors for OATP2B1-mediated 5 µM E3S uptake were determined. RESULTS: Our results showed that mulberrin, scutellarin, quercetin, and glycyrrhetinic acid were strong inhibitors of OATP2B1-mediate E3S uptake with IC50 values being 1.8, 2.0, 7.5, and 13.0 µM, which were comparable with their plasma concentrations in clinical trials. They also inhibited OATP-mediated uptake of atorvastatin, fluvastatin, and rosuvastatin. These results indicated that clinically relevant drug interactions could occur between these natural compounds and OATP2B1 substrate drugs. DISCUSSION AND CONCLUSION: The information obtained from this study might be helpful to predict and to avoid potential OATP2B1-mediated drug interactions.

[The interactions between natural products and OATP1B1].

Organic anion transporting polypeptide 1B1 (OATP1B1) is an important liver-specific uptake transporter, which mediates transport of numerous endogenous substances and drugs from blood into hepatocytes. To identify and investigate potential modulators of OATP1B1 from natural products, the effect of 21 frequently used natural compounds and extracts on OATP1B1-mediated fluorescein methotrexate transport was studied by using Chinese hamster ovary cells stably expressing OATP1B1 (CHO-OATP1B1) in 96-well plates. This method could be used for the screening of large compound libraries. Our studies showed that some flavonoids (e.g., quercetin, quercitrin, rutin, chrysanthemum flavonoids and mulberrin) and triterpenoids (e.g., glycyrrhetinic acid and glycyrrhizic acid) were inhibitors of OATP1B1 with IC50 values less than 16 µmol · L(-1). The IC50 value of glycyrrhetinic acid on OATP1B1 was comparable to its blood concentration in clinics, indicating an OATPlB1-mediated drug-drug interaction could occur. Structure-activity relationship analysis showed that flavonoids had much higher inhibitory activity than their glycosides. Furthermore, the type and length of saccharides had a significant effect on their activity. In addition, we used OATP1B1 substrates fluvastatin and rosuvastatin as probe drugs to investigate the substrate-dependent effect of several natural compounds on the function of OATP1B1 in vitro. Our results demonstrated that the effect of these natural products on the function of OATPlB1 was substrate-dependent. In summary, this study would be conducive to predicting and avoiding potential OATP1B1-mediated drug-drug and drug-food interactions and thus provide the experimental basis and guidance for rational drug use.