Therapeutic potential for renal fibrosis by targeting Smad3-dependent noncoding RNAs.

Renal fibrosis is a characteristic hallmark of chronic kidney disease (CKD) that ultimately results in renal failure, leaving patients with few therapeutic options. TGF-ß is a master regulator of renal fibrosis and mediates progressive renal fibrosis via both canonical and noncanonical signaling pathways. In the canonical Smad signaling, Smad3 is a key mediator in tissue fibrosis and mediates renal fibrosis via a number of noncoding RNAs (ncRNAs). In this regard, targeting Smad3-dependent ncRNAs may offer a specific therapy for renal fibrosis. This review highlights the significance and innovation of TGF-ß/Smad3-associated ncRNAs as biomarkers and therapeutic targets in renal fibrogenesis. In addition, the underlying mechanisms of these ncRNAs and their future perspectives in the treatment of renal fibrosis are discussed.

Conventional disease-modifying anti-rheumatic drugs combined with Chinese Herbal Medicines for rheumatoid arthritis: A systematic review and meta-analysis.

Rheumatoid Arthritis (RA) remains a major global public health challenge. Disease-modifying anti-rheumatic drugs (DMARDs) are standard therapeutic drugs for RA. Conventional DMARDs (c-DMARDs) are a subgroup of approved synthetic DMARDs. The c-DMARDs experienced lesser response with longer disease duration or drug exposure, and unwanted adverse events (AEs). The combination treatments (CTs) of c-DMARDs and Chinese Herbal Medicines (CHMs) were often used in RA clinical trials for increasing the therapeutic effectiveness and reducing the AEs. This systematic review aimed to evaluate the efficacy and safety of the CTs for RA. Databases were searched from inception to October 2020 for identification of randomized controlled trials (RCTs) that investigated the CTs in the management of RA. Twenty-three RCTs with 2,441 participants were included. The assessments and analyses found CTs improved American College of Rheumatology (ACR) 20 (RR: 1.33, 95% CI [1.21, 1.45], 10 studies, n=1,075) and alleviated AEs (RR: -0.40, 95% CI [-0.30, -0.53], 19 studies, n=2,011) in comparison with c-DMARDs. The CTs also significantly improved RA symptoms and patient-reported outcomes; reduced disease activity score (DAS) 28, serum acute-phase reactants and RA biomarkers. The five most commonly used herbs in included studies were Angelicae Sinensis Radix, Paeoniae Radix Alba, Cinnamomi Ramulus, Glycyrrhizae Radix et Rhizoma, and Clematidis Radix et Rhizoma. Pharmacological studies indicated these CHMs could contribute to the outcomes. The integrated CHMs potentially increased the overall effectiveness of c-DMARDs and alleviated AEs in management of RA. Large sample and rigorously designed RCTs are required for future studies.

Protective effect of quercetin on kidney diseases: From chemistry to herbal medicines.

Kidney injuries may trigger renal fibrosis and lead to chronic kidney disease (CKD), but effective therapeutic strategies are still limited. Quercetin is a natural flavonoid widely distributed in herbal medicines. A large number of studies have demonstrated that quercetin may protect kidneys by alleviating renal toxicity, apoptosis, fibrosis and inflammation in a variety of kidney diseases. Therefore, quercetin could be one of the promising drugs in the treatment of renal disorders. In the present study, we review the latest progress and highlight the beneficial role of quercetin in kidney diseases and its underlying mechanisms. The pharmacokinetics and bioavailability of quercetin and its proportion in herbal medicine will also be discussed.

Salvia miltiorrhiza Bunge (Danshen) and Bioactive Compound Tanshinone IIA Alleviates Cisplatin-Induced Acute Kidney Injury Through Regulating PXR/NF-κB Signaling.

Objective: The present study aims to provide evidence on the potential protective role of Salvia miltiorrhiza Bunge (Danshen) and its bioactive compound Tanshinone IIA (TanIIA) in AKI and to reveal the specific regulatory function of PXR/NF-κB signaling in AKI-induced renal inflammation. Methods: A network pharmacological analysis was used to study target genes and regulatory networks in the treatment of Salvia miltiorrhiza on AKI. Further experiments with in vivo AKI mouse model and in vitro studies were applied to investigate the renal protective effect of TanIIA in AKI. The mechanisms of TanIIA regulating PXR/NF-κB signaling in renal inflammation were also studied. Results: Network pharmacology had suggested the nuclear receptor family as new therapeutic targets of Salvia miltiorrhiza in AKI treatment. The in vivo studies had demonstrated that TanIIA improved renal function and inflammation by reducing necrosis and promoting the proliferation of tubular epithelial cells. Improved renal arterial perfusion in AKI mice with TanIIA treatment was also recorded by ultrasonography. In vitro studies had shown that TanIIA ameliorated renal inflammation by activating the PXR while inhibiting PXR-mediated NF-κB signaling. The results had suggested a role of PXR activation against AKI-induced renal inflammation. Conclusion: Salvia miltiorrhiza Bunge (Danshen) may protect the kidneys against AKI by regulating nuclear receptors. TanIIA improved cell necrosis proliferation and reduced renal inflammation by upregulating the expression of the PXR and inhibiting NF-κB signaling in a PXR-dependent manner. The PXR may be a potential therapeutic target for AKI treatment.

Biological effects and mechanisms of matrine and other constituents of Sophora flavescens in colorectal cancer.

The plant Sophora flavescens Ait. has been used in the clinical management of colorectal cancer (CRC). Its constituent compounds, notably the alkaloids matrine, oxymatrine, and sophoridine, have received considerable research attention in experimental models of CRC in vivo and in vitro. This review found that extracts of S. flavescens and/or its constituent compounds have been reported to inhibit CRC cell proliferation by inducing cell-cycle arrest at the G1 phase, inducing apoptosis via the intrinsic pathway, interfering in cancer metabolism, inhibiting metastasis and angiogenesis, regulating senescence and telomeres, regulating the tumour microenvironment and down-regulating cancer-related inflammation. In addition, matrine and oxymatrine reversed multi-drug resistance and enhanced the effects of chemotherapies. These anti-cancer effects were associated with regulation of several cellular signalling pathways including: MAPK/ERK, PI3K/AKT/mTOR, p38MAPK, NF-κB, Hippo/LATS2, TGF-ß/Smad, JAK/STAT3, RhoA/ROC, and Wnt/ ß-catenin pathways. These multiple actions in CRC suggest the alkaloids of S. flavescens may be therapeutic candidates for CRC management. Nevertheless, there remains considerable scope for future research into its flavonoid constituents, the effects of combinations of compounds, and the interaction between these compounds and anti-cancer drugs. In addition, more research is needed to investigate likely drug ligand-receptor interactions for each of the bioactive compounds.

Transforming Growth Factor-ß and Long Non-coding RNA in Renal Inflammation and Fibrosis.

Renal fibrosis is one of the most characterized pathological features in chronic kidney disease (CKD). Progressive fibrosis eventually leads to renal failure, leaving dialysis or allograft transplantation the only clinical option for CKD patients. Transforming growth factor-ß (TGF-ß) is the key mediator in renal fibrosis and is an essential regulator for renal inflammation. Therefore, the general blockade of the pro-fibrotic TGF-ß may reduce fibrosis but may risk promoting renal inflammation and other side effects due to the diverse role of TGF-ß in kidney diseases. Long non-coding RNAs (lncRNAs) are RNA transcripts with more than 200 nucleotides and have been regarded as promising therapeutic targets for many diseases. This review focuses on the importance of TGF-ß and lncRNAs in renal inflammation, fibrogenesis, and the potential applications of TGF-ß and lncRNAs as the therapeutic targets and biomarkers in renal fibrosis and CKD are highlighted.

Quercetin as a potential treatment for COVID-19-induced acute kidney injury: Based on network pharmacology and molecular docking study.

Kidneys are one of the targets for SARS-CoV-2, it is reported that up to 36% of patients with SARS-CoV-2 infection would develop into acute kidney injury (AKI). AKI is associated with high mortality in the clinical setting and contributes to the transition of AKI to chronic kidney disease (CKD). Up to date, the underlying mechanisms are obscure and there is no effective and specific treatment for COVID-19-induced AKI. In the present study, we investigated the mechanisms and interactions between Quercetin and SARS-CoV-2 targets proteins by using network pharmacology and molecular docking. The renal protective effects of Quercetin on COVID-19-induced AKI may be associated with the blockade of the activation of inflammatory, cell apoptosis-related signaling pathways. Quercetin may also serve as SARS-CoV-2 inhibitor by binding with the active sites of SARS-CoV-2 main protease 3CL and ACE2, therefore suppressing the functions of the proteins to cut the viral life cycle. In conclusion, Quercetin may be a novel therapeutic agent for COVID-19-induced AKI. Inhibition of inflammatory, cell apoptosis-related signaling pathways may be the critical mechanisms by which Quercetin protects kidney from SARS-CoV-2 injury.

TGF-ß in renal fibrosis: triumphs and challenges.

Renal fibrosis is a hallmark of chronic kidney disease. Although considerable achievements in the pathogenesis of renal fibrosis have been made, the underlying mechanisms of renal fibrosis remain largely to be explored. Now we have reached the consensus that TGF-ß is a master regulator of renal fibrosis. Indeed, TGF-ß regulates renal fibrosis via both canonical and noncanonical TGF-ß signaling. Moreover, ongoing renal inflammation promotes fibrosis as inflammatory cells such as macrophages, conventional T cells and mucosal-associated invariant T cells may directly or indirectly contribute to renal fibrosis, which is also tightly regulated by TGF-ß. However, anti-TGF-ß treatment for renal fibrosis remains ineffective and nonspecific. Thus, research into mechanisms and treatment of renal fibrosis remains highly challenging.

Diverse Role of TGF-ß in Kidney Disease.

Inflammation and fibrosis are two pathological features of chronic kidney disease (CKD). Transforming growth factor-ß (TGF-ß) has been long considered as a key mediator of renal fibrosis. In addition, TGF-ß also acts as a potent anti-inflammatory cytokine that negatively regulates renal inflammation. Thus, blockade of TGF-ß inhibits renal fibrosis while promoting inflammation, revealing a diverse role for TGF-ß in CKD. It is now well documented that TGF-ß1 activates its downstream signaling molecules such as Smad3 and Smad3-dependent non-coding RNAs to transcriptionally and differentially regulate renal inflammation and fibrosis, which is negatively regulated by Smad7. Therefore, treatments by rebalancing Smad3/Smad7 signaling or by specifically targeting Smad3-dependent non-coding RNAs that regulate renal fibrosis or inflammation could be a better therapeutic approach. In this review, the paradoxical functions and underlying mechanisms by which TGF-ß1 regulates in renal inflammation and fibrosis are discussed and novel therapeutic strategies for kidney disease by targeting downstream TGF-ß/Smad signaling and transcriptomes are highlighted.

The Synergistic Antitumor Effect of Tanshinone IIA Plus Adriamycin on Human Hepatocellular Carcinoma Xenograft in BALB/C Nude Mice and Their Influences on Cytochrome P450 CYP3A4 In Vivo.

OBJECTIVE: Hepatocellular carcinoma is one of the most common diseases that seriously threaten human life and health. In this study, we evaluated the inhibitory effect of tanshinone IIA (Tan IIA) combined with adriamycin (ADM) on human hepatocellular carcinoma and developed a platform to assess the function if Chinese herbal ingredients combined with chemotherapy drugs have synergistic antitumor effects in vivo. METHODS: Established animal model of human hepatocarcinoma HepG2 cell in nude mice. Mice were divided into model control group, Tan IIA group, ADM group, and Tan IIA + ADM group. The changes from general condition, weight, tumor volume, and inhibition rate were observed. The data were gathered from serum AST level and histopathological changes. The content and activity of cytochrome P450 were determined by spectrophotometric analysis. CYP3A4 protein expression was analyzed by western blotting. The binding model crystal structure of Tan IIA and ADM with pregnane X receptor (PXR) was evaluated by Discovery Studio 2.1. RESULTS: A combination of Tan IIA with ADM could improve life quality by relieving ADM toxicity, decreasing tumor volume, declining serum AST level, and improving liner pathological section in tumor-bearing mice. The inhibitory rates of Tan IIA, ADM, and cotreatment were 32.77%, 60.96%, and 73.18%, respectively. The Tan IIA group significantly enhanced the content of cytochrome b5, P450, and erythromycin-N-demethylase activity. CYP3A4 protein expression was enhanced obviously by the Tan IIA + ADM group. Virtual molecular docking showed that both Tan IIA and ADM could be stably docked with the same binding site of PXR but different interactions. CONCLUSIONS: Tan IIA in combination with ADM could improve the life quality in tumor-bearing mice and enhance the antitumor effect. The Tan IIA group increased the concentration of cytochrome P450 enzymes and activity. Combined Tan IIA with ADM could upregulate the CYP3A4 protein expression and make relevant interaction with protein PXR by virtual docking.

Non-Coding RNAs as Biomarkers and Therapeutic Targets for Diabetic Kidney Disease.

Diabetic kidney disease (DKD) is the most common diabetic complication and is a leading cause of end-stage kidney disease. Increasing evidence shows that DKD is regulated not only by many classical signaling pathways but also by epigenetic mechanisms involving chromatin histone modifications, DNA methylation, and non-coding RNA (ncRNAs). In this review, we focus on our current understanding of the role and mechanisms of ncRNAs, including microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) in the pathogenesis of DKD. Of them, the regulatory role of TGF-ß/Smad3-dependent miRNAs and lncRNAs in DKD is highlighted. Importantly, miRNAs and lncRNAs as biomarkers and therapeutic targets for DKD are also described, and the perspective of ncRNAs as a novel therapeutic approach for combating diabetic nephropathy is also discussed.

Matrine induces apoptosis in multiple colorectal cancer cell lines in vitro and inhibits tumour growth with minimum side effects in vivo via Bcl-2 and caspase-3.

BACKGROUND: The World Health Organization (WHO) reported that colorectal cancer (CRC) was the third most common cancer in men and the second in women, worldwide. Our previous meta-analysis found Sophora flavescens increased tumour response rate in randomised controlled trials of CRC. We hypothesised that its principal constituent matrine had exerted anti-tumour effects. PURPOSE: To elucidate its mechanisms of action we investigated the dose-related anti-tumour effects of matrine on four human CRC cell-lines: LS174T, Caco-2, SW1116 and RKO. In a LS174T xenografted tumour model in nude mice we assessed the effects of matrine and oxaliplatin on tumour volume, weight and morphology. Computer simulated dockings for target proteins were also conducted. METHODS AND DESIGN: Cell viability, cell cycle and apoptosis were measured by Cell Counting Kit-8 and flow cytometry, and Annexin V-FITC/PI double staining assay respectively. Western blot was performed to examine the expression of Bax, Bcl-2 and caspase-3 in the cells. The xenograft model and immunohistochemistry were used to investigate the effect of matrine in vivo. Oxaliplatin was set as positive control. Molecular docking was performed to predict the binding modes of matrine and oxaliplatin with target proteins using CDOCKER algorithm. RESULTS: Matrine inhibited proliferation of cancer cells in a dose- and time-dependent manner. Matrine induced cell-cycle arrest at G1/G0 phase, induced apoptosis and reduced expression of Bcl-2 and caspase-3 while up-regulating Bax and cleaved caspase-3 in the four CRC cells. In vivo, matrine significantly inhibited tumour growth without side effects on physical health compared to the negative (vehicle) control group. Mice in the oxaliplatin group lost vigour, became frail and lost weight. Expression of Bcl-2 in tumour tissue was lower and Bax expression was higher in the matrine-treated groups compared to the negative control. In computer-simulated docking, matrine successfully docked into active sites of Bcl-2 and caspase-3. CONCLUSION: Matrine inhibited growth of colorectal cancer cells in vitro and in vivo. A molecular mechanism was apoptosis induction via effects on Bcl-2, Bax and caspase-3. Moreover, matrine showed minimum side effects and may provide a candidate for the development of new therapies for colorectal cancer.

Matrine combined with cisplatin synergistically inhibited urothelial bladder cancer cells via down-regulating VEGF/PI3K/Akt signaling pathway.

BACKGROUND: Cisplatin is one of the first-line drugs for urothelial bladder cancer (UBC) treatment. However, its considerable side effects and the emergence of drug resistance are becoming major limitations for its application. This study aimed to investigate whether matrine and cisplatin could present a synergistic anti-tumor effect on UBC cells. METHODS: Cell viability assay was used to assess the suppressive effect of matrine and cisplatin on the proliferation of the UBC cells. Wound healing assay and transwell assay were applied respectively to determine the migration and invasion ability of the cells. The distribution of cell cycles, the generation of reactive oxygen species (ROS) and the apoptosis rate were detected by flow cytometry (FCM). The expressions of the relative proteins in apoptotic signal pathways and the epithelial-mesenchymal transition (EMT) related genes were surveyed by western blotting. The binding modes of the drugs within the proteins were detected by CDOCKER module in DS 2.5. RESULTS: Both matrine and cisplatin could inhibit the growth of the UBC cells in a time- and dose-dependent manner. When matrine combined with cisplatin at the ratio of 2000:1, they presented a synergistic inhibitory effect on the UBC cells. The combinative treatment could impair cell migration and invasion ability, arrest cell cycle in the G1 and S phases, increase the level of ROS, and induce apoptosis in EJ and T24 cells in a synergistic way. In all the treated groups, the expressions of E-cadherin, ß-catenin, Bax, and Cleaved Caspase-3 were up-regulated, while the expressions of Fibronectin, Vimentin, Bcl-2, Caspase-3, p-Akt, p-PI3K, VEGFR2, and VEGF proteins were down-regulated, and among them, the combination of matrine and cisplatin showed the most significant difference. Molecular docking algorithms predicted that matrine and cisplatin could be docked into the same active sites and interact with different residues within the tested proteins. CONCLUSIONS: Our results suggested that the combination of matrine and cisplatin could synergistically inhibit the UBC cells' proliferation through down-regulating VEGF/PI3K/Akt signaling pathway, indicating that matrine may serve as a new option in the combinative therapy in the treatment of UBC.

Tanshinone IIA combined with adriamycin inhibited malignant biological behaviors of NSCLC A549 cell line in a synergistic way.

BACKGROUND: The study was designed to develop a platform to verify whether the extract of herbs combined with chemotherapy drugs play a synergistic role in anti-tumor effects, and to provide experimental evidence and theoretical reference for finding new effective sensitizers. METHODS: Inhibition of tanshinone IIA and adriamycin on the proliferation of A549, PC9 and HLF cells were assessed by CCK8 assays. The combination index (CI) was calculated with the Chou-Talalay method, based on the median-effect principle. Migration and invasion ability of A549 cells were determined by wound healing assay and transwell assay. Flow cytometry was used to detect the cell apoptosis and the distribution of cell cycles. TUNEL staining was used to detect the apoptotic cells. Immunofluorescence staining was used to detect the expression of Cleaved Caspase-3. Western blotting was used to detect the proteins expression of relative apoptotic signal pathways. CDOCKER module in DS 2.5 was used to detect the binding modes of the drugs and the proteins. RESULTS: Both tanshinone IIA and adriamycin could inhibit the growth of A549, PC9, and HLF cells in a dose- and time-dependent manner, while the proliferative inhibition effect of tanshinone IIA on cells was much weaker than that of adriamycin. Different from the cancer cells, HLF cells displayed a stronger sensitivity to adriamycin, and a weaker sensitivity to tanshinone IIA. When tanshinone IIA combined with adriamycin at a ratio of 20:1, they exhibited a synergistic anti-proliferation effect on A549 and PC9 cells, but not in HLF cells. Tanshinone IIA combined with adriamycin could synergistically inhibit migration, induce apoptosis and arrest cell cycle at the S and G2 phases in A549 cells. Both groups of the single drug treatment and the drug combination up-regulated the expressions of Cleaved Caspase-3 and Bax, but down-regulated the expressions of VEGF, VEGFR2, p-PI3K, p-Akt, Bcl-2, and Caspase-3 protein. Compared with the single drug treatment groups, the drug combination groups were more statistically significant. The molecular docking algorithms indicated that tanshinone IIA could be docked into the active sites of all the tested proteins with H-bond and aromatic interactions, compared with that of adriamycin. CONCLUSIONS: Tanshinone IIA can be developed as a novel agent in the postoperative adjuvant therapy combined with other anti-tumor agents, and improve the sensibility of chemotherapeutics for non-small cell lung cancer with fewer side effects. In addition, this experiment can not only provide a reference for the development of more effective anti-tumor medicine ingredients, but also build a platform for evaluating the anti-tumor effects of Chinese herbal medicines in combination with chemotherapy drugs.

Baicalein decreases side population proportion via inhibition of ABCG2 in multiple myeloma cell line RPMI 8226 in vitro.

OBJECTIVE: To investigate the effect of baicalein on side population in human multiple myeloma cell line RPMI 8226 and the underlying molecular mechanisms in vitro and in silico. METHODS: MTT assay was applied to detect the anti-proliferation effect of baicalein. The detection of side population cells is based on the Hoechst 33342 exclusion assay technique and flow cytometric analysis. Western blotting assay was used to explore the expression of ABCG2 protein. Homology modeling and molecular docking were performed with Discovery Studio 2.1. RESULTS: Baicalein decreased both cell viability with IC50=168.5 µM and the proportion of SP cells in a dose-dependent manner. Correspondingly, it significantly decreased the expression level of ABCG2 protein. Baicalein also shared similar binding sites and modes with fumitremorgin C to the protein. CONCLUSIONS: Baicalein possessed novel anticancer properties, such as anti-proliferation and drug efflux inhibition in side population cells, which suggested its potential feature of targeting cancer stem cells of multiple myeloma.

Antidiarrheal properties of different extracts of Chinese herbal medicine formula Bao-Xie-Ning.

OBJECTIVE: Bao-Xie-Ning (BXN), a traditional Chinese herbal medicine (CHM) formula composed of Fructus Evodiae, Flos Caryophylli and Cortex Cinnamomi, and used for the treatment of infant diarrheal illness, was subject to systematic assessment for its putative multiple pharmacodynamic effects and pharmacological antidiarrheal mechanisms. METHODS: High-performance liquid chromatography-diode array detector-electrospray ionization-mass spectrometric/mass spectrometry was developed and validated for identification and quantification of the main constituents in different extracts of BXN. Male Kunming mice weighing 20 to 25 g were used for detecting the antidiarrheal activity of the extracts. Ethanolic extract (EE), volatile oil extract (VOE), and aqueous extract (AE) of BXN were respectively subjected to pharmacodynamic and pharmacological comparison in assessing antidiarrheal effects with senna-induced diarrhea, castor oil-induced diarrhea, acetic acid-induced writhing assay, and isolated duodenum test. RESULTS: The highest yields of three detected components of BXN, rutaecarpine, eugenol and cinnamaldehyde were observed in EE. EE showed the most remarkable antidiarrheal activity in dose-dependent and time-dependent manners in both senna- and castor oil-induced diarrhea models, and presented dose-dependent analgesic activity in acetic acid-induced algesthesia model. In addition, EE extract of BXN also exhibited strong antimobility action on the intestine and strongest depression on spontaneous contraction of isolated duodenum. CONCLUSION: Ethanol extraction is an efficient method to extract the active constituents of BXN. BXN extract demonstrated multiple pharmacological activities affecting the main mechanisms of diarrhea, which validated BXN's usage in the comprehensive clinical treatment of diarrhea.

Scutellaria extract decreases the proportion of side population cells in a myeloma cell line by down-regulating the expression of ABCG2 protein.

BACKGROUND AND AIMS: Scutellaria is one of the most popular traditional Chinese herbal remedies against various human diseases, including cancer. In this study, we examined the active effects of Scutellaria extract and its main flavonoid constituents on the proportion of side population cells within human multiple myeloma cell line RPMI8226 in vitro and explored the potential molecular mechanisms involved. MATERIALS AND METHODS: The contents of flavonoids in ethanolic extract of Scutellaria baicalensis Georgi were determined using high performance liquid chromatography. The antiproliferative effect of the ethanolic extract on RPMI-8226 was determined by CCK assay. Apoptosis was measured by annexin combining with propidium iodide in a flow cytometer. Cell cycle analysis was performed by propidium iodide staining in combination with flow cytometry analysis. Hoechst 33342 exclusion assay was used for the identification of side population within RPMI8226 cells. The expression of ABCG2 protein was assessed by Western blotting assay. RESULTS: The content of major flavonoids constitutents of Scutellaria extract was baicalin (10.2%), wogonoside (2.50%), baicalein (2.29%), and wogonin (0.99%), respectively. The crude Scutellaria extract did not show significant anti-proliferative effect, apoptosis induction and cell cycle arrest in RPMI-8226 within the concentrations of 1-75µg/mL. However, the ethanolic extract, baicalein, wogonin and baicalin reduced the side population cells in RPMI-8226, and data showed that baicalein and wogonin had stronger inhibitory effects. Correspondingly, they also exhibited significant effects on decreasing the expression level of ABCG2 protein in RPMI-8226 in vitro. CONCLUSIONS: Our results for the first time demonstrated a novel mechanism of action for Scutellaria extract and its main active flavonoids, namely targeting SP cells by modulating the expression of ABCG2 protein. This study provides an insight for new therapeutic strategies targeting cancer stem cells of multiple myeloma.