Cellular and molecular mechanisms of oroxylin A in cancer therapy: Recent advances

Seeking an effective and safe scheme is the common goal of clinical treatment of tumor patients. In recent years, traditional Chinese medicine has attracted more and more attention in order to discover new drugs with good anti-tumor effects. Oroxylin A (OA) is a compound found in natural Oroxylum indicum and Scutellaria baicalensis Georgi plants and has been used in the treatment of various cancers. Studies have shown that OA has a wide range of powerful biological activities and plays an important role in neuroprotection, anti-inflammation, anti-virus, anti-allergy, anti-tumor and so on. OA shows high efficacy in tumor treatment. Therefore, it has attracted great attention of researchers all over the world. This review aims to discuss the anti-tumor effects of OA from the aspects of cell cycle arrest, induction of cell proliferation and apoptosis, induction of autophagy, anti-inflammation, inhibition of glycolysis, angiogenesis, invasion, metastasis and reversal of drug resistance. In addition, the safety and toxicity of the compound were also discussed. As a next step, to clarify the benefits and adverse effects of Oroxylin A in cancer patients further experiments, especially clinical trials, are needed.

AFP deletion leads to anti-tumorigenic but pro-metastatic roles in liver cancers with concomitant CTNNB1 mutations

HCC remains one of the most prevalent and deadliest cancers. Serum AFP level is a biomarker for clinical diagnosis of HCC, instead the contribution of AFP to HCC development is clearly highly complex. Here, we discussed the effect of AFP deletion in the tumorigenesis and progression of HCC. AFP deletion in HepG2 cells inhibited the cell proliferation by inactivating PI3K/AKT signaling. Surprisingly, AFP KO HepG2 cells appeared the increasing metastatic capacity and EMT phenotype, which was attributed to the activation of WNT5A/β-catenin signal. Further studies revealed that the activating mutations of CTNNB1 was closely related with the unconventional pro-metastatic roles of AFP deletion. Consistently, the results of DEN/CCl4-induced HCC mouse model also suggested that AFP knockout suppressed the growth of HCC primary tumors, but promoted lung metastasis. Despite the discordant effect of AFP deletion in HCC progression, a drug candidate named OA showed the potent suppression of HCC tumor growth by interrupting AFP-PTEN interaction and, importantly, reduced the lung metastasis of HCC via angiogenesis suppression. Thus, this study demonstrates an unconventional effect of AFP in HCC progression, and suggests a potent candidate strategy for HCC therapy.

Anticancer potential of oroxylin A: from mechanistic insight to synergistic perspectives

Oroxylin A (OA), a well-known constituent of the root of Scutellariae plants, has been used in ethnomedicine already for centuries in treating various neoplastic disorders. However, only recent molecular studies have revealed the different mechanisms behind its action, demonstrating antiproliferative, anti-inflammatory, and proapoptotic effects, restricting also the spread of cancer cells to distant organs. A variety of cellular targets and modulated signal transduction pathways regulated by OA have been determined in diverse cells derived from different malignant tissues. In this review article, these anticancer activities are thoroughly described, representing OA as a potential lead structure for the design of novel more potent anticancer medicines. In addition, co-effects of this natural compound with conventional anticancer agents are analyzed and the advantages provided by nanotechnological methods for more efficient application of OA are discussed. In this way, OA might represent an excellent example of using ethnopharmacological knowledge for designing modern medicines.

Modulation of diverse oncogenic signaling pathways by oroxylin A: An important strategy for both cancer prevention and treatment

BACKGROUND

Regardless of major advances in diagnosis, prevention and treatment strategies, cancer is still a foreboding cause due to factors like chemoresistance, radioresistance, adverse side effects and cancer recurrence. Therefore, continuous development of unconventional approaches is a prerequisite to overcome foregoing glitches. Natural products have found their way into treatment of serious health conditions, including cancer since ancient times. The compound oroxylin A (OA) is one among those with enormous potential against different malignancies. It is a flavonoid obtained from the several plants such as Oroxylum indicum, Scutellaria baicalensis and S. lateriflora, Anchietea pyrifolia, and Aster himalaicus.

PURPOSE

The main purpose of this study is to comprehensively elucidate the anticancerous effects of OA against various malignancies and unravel their chemosensitization and radiosensitization potential. Pharmacokinetic and pharmacodynamic studies of OA have also been investigated.

METHOD

The literature on antineoplastic effects of OA was searched in PubMed and Scopus, including in vitro and in vivo studies and is summarized based on a systematic review protocol prepared according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The term "oroxylin A" was used in combination with "cancer" and all the title, abstracts and keywords appeared were considered.

RESULTS

In Scopus, a total of 157 articles appeared out of which 103 articles that did not meet the eligibility criteria were eliminated and 54 were critically evaluated. In PubMed, from the 85 results obtained, 26 articles were eliminated and 59 were included in the preparation of this review. Mounting number of studies have illustrated the anticancer effects of OA, and its mechanism of action.

CONCLUSION

OA is a promising natural flavonoid possessing wide range of pleiotropic properties and is a potential anticancer agent. It has a great potential in the treatment of multiple cancers including brain, breast, cervical, colon, esophageal, gall bladder, gastric, hematological, liver, lung, oral, ovarian, pancreatic and skin. However, lack of pharmacokinetic studies, toxicity assessments, and dose standardization studies and adverse effects limit the optimization of this compound as a therapeutic agent.

Oroxylin A: A Promising Flavonoid for Prevention and Treatment of Chronic Diseases

There have been magnificent advancements in the understanding of molecular mechanisms of chronic diseases over the past several years, but these diseases continue to be a considerable cause of death worldwide. Most of the approved medications available for the prevention and treatment of these diseases target only a single gene/protein/pathway and are known to cause severe side effects and are less effective than they are anticipated. Consequently, the development of finer therapeutics that outshine the existing ones is far-reaching. Natural compounds have enormous applications in curbing several disastrous and fatal diseases. Oroxylin A (OA) is a flavonoid obtained from the plants Oroxylum indicum, Scutellaria baicalensis, and S. lateriflora, which have distinctive pharmacological properties. OA modulates the important signaling pathways, including NF-κB, MAPK, ERK1/2, Wnt/β-catenin, PTEN/PI3K/Akt, and signaling molecules, such as TNF-α, TGF-ꞵ, MMPs, VEGF, interleukins, Bcl-2, caspases, HIF-1α, EMT proteins, Nrf-2, etc., which play a pivotal role in the molecular mechanism of chronic diseases. Overwhelming pieces of evidence expound on the anti-inflammatory, anti-bacterial, anti-viral, and anti-cancer potentials of this flavonoid, which makes it an engrossing compound for research. Numerous preclinical and clinical studies also displayed the promising potential of OA against cancer, cardiovascular diseases, inflammation, neurological disorders, rheumatoid arthritis, osteoarthritis, etc. Therefore, the current review focuses on delineating the role of OA in combating different chronic diseases and highlighting the intrinsic molecular mechanisms of its action.

Evidence for Anticancer Effects of Chinese Medicine Monomers on Colorectal Cancer

Colorectal cancer is one of the most commonly occurring cancers worldwide. Although clinical reports have indicated the anticancer effects of Chinese herbal medicine, the multiple underlying molecular and biochemical mechanisms of action remain to be fully characterized. Chinese medicine (CM) monomers, which are the active components of CM, serve as the material basis of the functional mechanisms of CM. The aim of this review is to summarize the current experimental evidence from in vitro, in vivo, and clinical studies for the effects of CM monomers in colorectal cancer prevention and treatment, providing some useful references for future research.

Cancer Chemotherapy via Natural Bioactive Compounds

BACKGROUND

Cancer-induced mortality is increasingly prevalent globally which skyrocketed the necessity to discover new/novel safe and effective anticancer drugs. Cancer is characterized by the continuous multiplication of cells in the human which is unable to control. Scientific research is drawing its attention towards naturally-derived bioactive compounds as they have fewer side effects compared to the current synthetic drugs used for chemotherapy.

OBJECTIVE

Drugs isolated from natural sources and their role in the manipulation of epigenetic markers in cancer are discussed briefly in this review article.

METHODS

With advancing medicinal plant biotechnology and microbiology in the past century, several anticancer phytomedicines were developed. Modern pharmacopeia contains at least 25% herbal-based remedy including clinically used anticancer drugs. These drugs mainly include the podophyllotoxin derivatives vinca alkaloids, curcumin, mistletoe plant extracts, taxanes, camptothecin, combretastatin, and others including colchicine, artesunate, homoharringtonine, ellipticine, roscovitine, maytanasin, tapsigargin,andbruceantin.

RESULTS

Compounds (psammaplin, didemnin, dolastin, ecteinascidin,and halichondrin) isolated from marine sources and animals such as microalgae, cyanobacteria, heterotrophic bacteria, invertebrates. They have been evaluated for their anticancer activity on cells and experimental animal models and used chemotherapy.Drug induced manipulation of epigenetic markers plays an important role in the treatment of cancer.

CONCLUSION

The development of a new drug from isolated bioactive compounds of plant sources has been a feasible way to lower the toxicity and increase their effectiveness against cancer. Potential anticancer therapeutic leads obtained from various ethnomedicinal plants, foods, marine, and microorganisms are showing effective yet realistically safe pharmacological activity. This review will highlight important plant-based bioactive compounds like curcumin, stilbenes, terpenes, other polyphenolic phyto-compounds, and structurally related families that are used to prevent/ ameliorate cancer. However, a contribution from all possible fields of science is still a prerequisite for discovering safe and effective anticancer drugs.

An ethnopharmacological review on the therapeutical properties of flavonoids and their mechanisms of actions: A comprehensive review based on up to date knowledge

Flavonoids -a class of low molecular weight secondary metabolites- are ubiquitous and cornucopia throughout the plant kingdom. Structurally, the main structure consists of C6-C3-C6 rings with different substitution patterns so that many sub-classes are obtained, for example: flavonols, flavonolignans, flavonoid glycosides, flavans, anthocyanidins, aurones, anthocyanidins, flavones, neoflavonoids, chalcones, isoflavones, flavones and flavanones. Flavonoids are evaluated to have drug like nature since they possess different therapeutic activities, and can act as cardioprotective, antiviral, antidiabetic, anti-inflammatory, antibacterial, anticancer, and also work against Alzheimer's disease and others. However, information on the relationship between their structure and biological activity is scarce. Therefore, the present review tries to summarize all the therapeutic activities of flavonoids, their mechanisms of action and the structure activity relationship.

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Latest updated ethnopharmacological review of the therapeutic effects of flavonoids.

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Flavonoids are attracting attention because of their therapeutic properties.

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Flavonoids are valuable candidates for drug development against many dangerous diseases.

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This overview summarizes the most important therapeutic effect and mechanism of action of flavonoids.

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General knowledge about the structure activity relationship of flavonoids is summarized.

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Substitution of chemical groups in the structure of flavonoids can significantly change their biological and chemical properties.

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The chemical properties of the basic flavonoid structure should be considered in a drug-based structural program.

Nanosponges Encapsulated Phytochemicals for Targeting Cancer: A Review

Cancer is the most ruinous disease globally. Natural products have impressive characteristics, such as exceptional chemical versatility, chemical and biological properties of macromolecular specificity and less toxicity which make them good leads in finding novel drugs. The phytochemicals not only help to prevent but also treat chronic cancerous conditions. The present review attempts to put forth some selected anticancer phytochemicals that had reported omics characteristic and specifically suppressed cancer with in vitro and in vivo activity. Certain issues pertaining to anticancer phytochemicals like delivery to target site in the body and achieving controlled release in order to prevent overdoses have been a major concern for medical researchers worldwide. The most conventional chemotherapy protocols for the treatment of cancer lead to adverse effects that limit biological efficacy and compromise patient outcomes. In order to defeat incompetency of current and upcoming natural anticancer agents and to attain targeted drug delivery with good efficacy and fewer side effects, there is a special focus on novel nanostructured particles and nano approaches consisting of carrier system. Recent studies have led to the discovery of mesoporous and nanoporous drug delivery mechanisms, such as inorganic or organic-based nanosponges. The metal based inorganic systems have exhibited toxicity and non-biodegradable character in vivo. As a result of problems related to inorganic systems, major shift of research from inorganic to organic nanosystems has occurred. About decades ago, researchers developed organic nanosponges to control the limitation of drug delivery and cancer therapies. This review article discusses the development and application of nanosponges encapsulated phytochemicals for cancer therapy.

Oroxylin A reverses hypoxia-induced cisplatin resistance through inhibiting HIF-1α mediated XPC transcription

Hypoxia is a key concern during the treatment of non-small cell lung cancer (NSCLC), and hypoxia-inducible factor 1 alpha (HIF-1α) has been associated with increased tumor resistance to therapeutic modalities such as cisplatin. Compensatory activation of nucleotide excision repair (NER) pathway is the major mechanism that accounts for cisplatin resistance. In the present study, we suggest a novel strategy to improve the treatment of NSCLC and overcome the hypoxia-induced cisplatin resistance by cotreatment with Oroxylin A, one of the main bioactive flavonoids of Scutellariae radix. Based on the preliminary screening, we found that xeroderma pigmentosum group C (XPC), an important DNA damage recognition protein involved in NER, dramatically increased in hypoxic condition and contributed to hypoxia-induced cisplatin resistance. Further data suggested that Oroxylin A significantly reversed the hypoxia-induced cisplatin resistance through directly binding to HIF-1α bHLH-PAS domain and blocking its binding to HRE3 transcription factor binding sites on XPC promoter which is important to hypoxia-induced XPC transcription. Taken together, our findings not only demonstrate a crucial role of XPC dependent NER in hypoxia-induced cisplatin resistance, but also suggest a previously unrecognized tumor suppressive mechanism of Oroxylin A in NSCLC which through sensitization of cisplatin-mediated growth inhibition and apoptosis under hypoxia.

Oroxylin A reversed Fibronectin-induced glioma insensitivity to Temozolomide by suppressing IP3R1/AKT/β-catenin pathway

AIMS

Cell adhesion mediated-drug resistance (CAM-DR) is one of main reasons for. the limitation to chemotherapy, but the underlying mechanism remains unclear in glioma. In this study, we investigated the mechanism of CAM-DR induced by Fibronectin (Fn). Besides, we studied the reversal effect of Oroxylin A, a natural flavonoid extracted from Scutellaria radix, on Temozolomide (TMZ) insensitivity of glioma cells.

MAIN METHODS

Human Fn protein was used to mimic cell adhesion model and investigate its effect on the insensitivity of glioma cells to TMZ. Moreover, Oroxylin A was studied regarding its reversal effect on TMZ insensitivity of glioma via multiple molecular biological methods such as MTT, cell apoptosis assay, siRNA transfection, western blot, immunofluorescence assay.

KEY FINDINGS

Fn could decrease the apoptosis-inducing effect of TMZ and led to the CAM-DR in glioma cells. Further studies showed that up-regulations of IP₃R1 and intracellular Ca²⁺ level induced the activation of AKT kinase which increased the phosphorylation of GSK-3β and subsequently caused the entry of β-catenin into the nucleus. Knocking down IP₃R1 significantly improved the sensitivity of glioma cells to TMZ. Meanwhile, after treatment with low-toxic concentration of Oroxylin A, the apoptosis induced by TMZ under Fn condition increased dramatically. Furthermore, our results revealed that Oroxylin A markedly inhibited the expression of IP₃R1 and the activation of AKT/β-catenin pathway.

SIGNIFICANCE

Oroxylin A could reverse the insensitivity of TMZ via suppressing IP₃R1/AKT/β-catenin pathway and it might be helpful for enhancing the anti-cancer effect of TMZ in glioma.

Natural flavonoids for the prevention of colon cancer: A comprehensive review of preclinical and clinical studies

Flavonoids comprise a group of natural polyphenols consisting of more than 5,000 subtypes mostly existing in fruits and vegetables. Flavonoids consumption could potentially attenuate the incidence and recurrence risk of colorectal cancers through their antiperoxidative, antioxidant, and anti-inflammatory effects. In addition, these compounds regulate the mitochondrial function, balance the bacterial flora and promote the apoptosis process in cancerous cells. However, some previous data failed to show the effectiveness of flavonoids in reducing the risk of colorectal cancer. In this study, we have reviewed the efficacy of different flavonoids subtypes on the risk of colon cancer and molecular mechanisms involved in this process in both clinical and animal studies. In addition, we tried to elucidate the potential synergy between these compounds and current colorectal cancer treatments.

Oroxylin a Inhibits the Protection of Bone Marrow Microenvironment on CML Cells Through CXCL12/CXCR4/P-gp Signaling Pathway

Imatinib (IM) resistance could have significant impact on the survival time of the CML-patients treated with IM. Previous studies have shown that the protective effects of the bone marrow stroma cells (BMSCs) on CML cells are achieved by the secretion of CXCL12. The aim of this study was to investigate whether Oroxylin A could reverse the protective effect of BMSCs on CML cells and illuminate the underlying mechanisms. The results showed that CXCL12 could enhance the resistance potential of K562 and KU812 cells to IM by increasing the expression of CXCR4, thus promoting the translocation of β-catenin into nucleus and subsequently increasing the expression of P-gp in K562 and KU812 cells. What's more, IM resistance could also be partially reversed by CXCR4 siRNA transfection. Moreover, the reverse effect of IM resistance by Oroxylin A was demonstrated by the inhibition of β-catenin/P-gp pathway via the decrease of CXCR4 in vitro. The in vivo study also showed that Oroxylin A could decrease the expression of P-gp and β-catenin in mice bone marrow with low toxicity, which could be consistent with the mechanisms verified in vitro studies. In conclusion, all these results showed that Oroxylin A improved the sensitivity of K562 and KU812 cells to IM in BM microenvironment by decreasing the expression of CXCR4 and then inhibiting β-catenin/P-gp pathway.

Polyphenols of Chinese skullcap roots: from chemical profiles to anticancer effects

Great efforts have been made to identify the principle bioactive constituents of Chinese herbs and to unravel the molecular mechanisms behind their anticancer effects.

Scutellaria baicalensis and Cancer Treatment: Recent Progress and Perspectives in Biomedical and Clinical Studies

Scutellaria baicalensis (Huangqin in Chinese) is a major traditional Chinese medicine (TCM) herb, which has a long history of use in the treatment of a variety of symptoms correlated with cancer. In the past decade, the potential of S. baicalensis and single compounds derived from it as anticancer agents targeting various pathways has received extensive research attention. Specifically, the proliferation and metastases inhibiting properties of the single compounds in cancer have been studied; however, the underlying mechanisms remain unclear. This review summarizes the various mechanisms, pathways and molecular targets involved in the anticancer activity of S. baicalensis and its single compounds. However, the aim of this review is to provide a more thorough view of the last 10 years to link traditional use with modern research and to highlight recently discovered molecular mechanisms. Extracts and major flavonoids derived from S. baicalensis have been found to possess anticancer effects in multiple cancer cell lines both in vitro and in vivo. Further investigation is warranted to better understand the underlying mechanisms and to discover novel targets and cancer therapeutic drugs that may improve both the survival and quality of life of cancer patients.

New Insights toward Colorectal Cancer Chemotherapy Using Natural Bioactive Compounds

Combination therapy consists in the simultaneous administration of a conventional chemotherapy drug (or sometimes, a radiotherapy protocol) together with one or more natural bioactives (usually from plant or fungal origin) of small molecular weight. This combination of anticancer drugs may be applied to cell cultures of tumor cells, or to an animal model for a cancer type (or its xenograft), or to a clinical trial in patients. In this review, we summarize current knowledge describing diverse synergistic effects on colorectal cancer cell cultures, animal models, and clinical trials of various natural bioactives (stilbenes, flavonoids, terpenes, curcumin, and other structural families), which may be important with respect to diminish final doses of the chemotherapy drug, although maintaining its biological effect. This is important as these approaches may help reduce side effects in patients under conventional chemotherapy. Also, these molecules may exerts their synergistic effects via different cell cycle pathways, including different ones to those responsible of resistance phenotypes: transcription factors, membrane receptors, adhesion and structural molecules, cell cycle regulatory components, and apoptosis pathways.

Overview of Oroxylin A: A Promising Flavonoid Compound

Oroxylin A is one of the main active components extracted from Scutellariae radix. It has been proved that oroxylin A possesses a broad spectrum of pharmacological functions, including anti-cancer, antiinflammation, neuroprotective, anti-coagulation and so on. The pharmacological activity of oroxylin A has been studied in vitro and on animal models, which reflected its promising potency in disease treatment. This review aims to recapitulate the pharmacological function and the molecular mechanisms of oroxylin A, as well as its sources, extraction, synthesis and toxicity study. These data confirmed the therapeutic potential of oroxylin A and provided reference for further development. Copyright © 2016 John Wiley & Sons, Ltd.

Oroxylin A promotes PTEN-mediated negative regulation of MDM2 transcription via SIRT3-mediated deacetylation to stabilize p53 and inhibit glycolysis in wt-p53 cancer cells

Introduction

p53 plays important roles in regulating the metabolic reprogramming of cancer, such as aerobic glycolysis. Oroxylin A is a natural active flavonoid with strong anticancer effects both in vitro and in vivo.

Methods

wt-p53 (MCF-7 and HCT116 cells) cancer cells and p53-null H1299 cancer cells were used. The glucose uptake and lactate production were analyzed using Lactic Acid production Detection kit and the Amplex Red Glucose Assay Kit. Then, the protein levels and RNA levels of p53, mouse double minute 2 (MDM2), and p53-targeted glycolytic enzymes were quantified using Western blotting and quantitative polymerase chain reaction (PCR), respectively. Immunoprecipitation were performed to assess the binding between p53, MDM2, and sirtuin-3 (SIRT3), and the deacetylation of phosphatase and tensin homolog (PTEN). Reporter assays were performed to assess the transcriptional activity of PTEN. In vivo, effects of oroxylin A was investigated in nude mice xenograft tumor-inoculated MCF-7 or HCT116 cells.

Results

Here, we analyzed the underlying mechanisms that oroxylin A regulated p53 level and glycolytic metabolism in wt-p53 cancer cells, and found that oroxylin A inhibited glycolysis through upregulating p53 level. Oroxylin A did not directly affect the transcription of wt-p53, but suppressed the MDM2-mediated degradation of p53 via downregulating MDM2 transcription in wt-p53 cancer cells. In further studies, we found that oroxylin A induced a reduction in MDM2 transcription by promoting the lipid phosphatase activity of phosphatase and tensin homolog, which was upregulated via sirtuin3-mediated deacetylation. In vivo, oroxylin A inhibited the tumor growth of nude mice-inoculated MCF-7 or HCT116 cells. The expression of MDM2 protein in tumor tissue was downregulated by oroxylin A as well.

Conclusions

These results provide a p53-independent mechanism of MDM2 transcription and reveal the potential of oroxylin A on glycolytic regulation in both wt-p53 and mut-p53 cancer cells. The studies have important implications for the investigation on anticancer effects of oroxylin A, and provide the academic basis for the clinical trial of oroxylin A in cancer patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s13045-015-0137-1) contains supplementary material, which is available to authorized users.

miR-129 promotes apoptosis and enhances chemosensitivity to 5-fluorouracil in colorectal cancer

Resistance to fluoropyrimidine-based chemotherapy is the major reason for the failure of advanced colorectal cancer (CRC) treatment. The lack of ability of tumor cells to undergo apoptosis after genotoxic stress is the key contributor to this intrinsic mechanism. Mounting evidence has demonstrated that non-coding microRNAs (miRNAs) are crucial regulators of gene expression, in particular, under acute genotoxic stress. However, there is still limited knowledge about the role of miRNAs in apoptosis. In this study, we discovered a novel mechanism mediated by microRNA-129 (miR-129) to trigger apoptosis by suppressing a key anti-apoptotic protein, B-cell lymphoma 2 (BCL2). Ectopic expression of miR-129 promoted apoptosis, inhibited cell proliferation and caused cell-cycle arrest in CRC cells. The intrinsic apoptotic pathway triggered by miR-129 was activated by cleavage of caspase-9 and caspase-3. The expression of miR-129 was significantly downregulated in CRC tissue specimens compared with the paired normal control samples. More importantly, we demonstrated that miR-129 enhanced the cytotoxic effect of 5-fluorouracil both in vitro and in vivo. These results suggest that miR-129 has a unique potential as a tumor suppressor and a novel candidate for developing miR-129-based therapeutic strategies in CRC.