Wogonin, a Plant Flavone, Potentiates Etoposide-Induced Apoptosis in Cancer Cells

Wogonin, as a potent anticancer compound: From chemistry to cellular interactions

Chinese native medicine Scutellaria baicalensis Georgi, also referred to as Chinese skullcap or Huang-Qin, is frequently used to treat cancer, viral infections, and seizures. This plant's abundance of flavones (wogonoside) and their related aglycones (wogonin) is responsible for many of its pharmacologic effects. A significant ingredient in S. baicalensis that has been the subject of the most research is wogonin. Numerous preclinical investigations revealed that wogonin suppresses tumor growth by cell cycle arrest, stimulating cell death and preventing metastasis. This review focuses on a complete overview of published reports that suggest chemopreventive action of wogonin and the mechanistic insights behind these neoplastic activities. It also emphasizes the synergistic improvements made by wogonin in chemoprevention. The factual data in this mini-review stimulate additional research on chemistry and toxicological profile of wogonin to confirm its safety issues. This review will encourage researchers to generalize the merits of wogonin to be used as potential compound for cancer treatment.

Fascinating Chemopreventive Story of Wogonin: A Chance to Hit on the Head in Cancer Treatment

Cancer, global havoc, is a group of debilitating diseases that strikes family as well as society. Cancer cases are drastically increasing these days. Despite many therapies and surgical procedures available, cancer is still difficult to control due to limited effective therapies or targeted therapies. Natural products can produce lesser side effects to the normal cells, which are the major demerit of chemotherapies and radiation. Wogonin, a natural product extracted from the plant, Scutellaria baicalensis has been widely studied and found with a high caliber to tackle most of the cancers via several mechanisms that include intrinsic as well as extrinsic apoptosis signaling pathways, carcinogenesis diminution, telomerase activity inhibition, metastasis inhibition in the inflammatory microenvironment, anti-angiogenesis, cell growth inhibition and arrest of the cell cycle, increased generation of H₂O₂ and accumulation of Ca²⁺ and also as an adjuvant along with anticancer drugs. This article discusses the role of wogonin in various cancers, its synergism with various drugs, and the mechanism by which wogonin controls tumor growth.

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.

Established Human Cell Lines as Models to Study Anti-leukemic Effects of Flavonoids

Despite the extensive work on pathological mechanisms and some recent advances in the treatment of different hematological malignancies, leukemia continues to present a significant challenge being frequently considered as incurable disease. Therefore, the development of novel therapeutic agents with high efficacy and low toxicity is urgently needed to improve the overall survival rate of patients. In this comprehensive review article, the current knowledge about the anticancer activities of flavonoids as plant secondary polyphenolic metabolites in the most commonly used human established leukemia cell lines (HL-60, NB4, KG1a, U937, THP-1, K562, Jurkat, CCRF- CEM, MOLT-3, and MOLT-4) is compiled, revealing clear anti-proliferative, pro-apoptotic, cell cycle arresting, and differentiation inducing effects for certain compounds. Considering the low toxicity of these substances in normal blood cells, the presented data show a great potential of flavonoids to be developed into novel anti-leukemia agents applicable also in the malignant cells resistant to the current conventional chemotherapeutic drugs.

Wogonin inhibits the proliferation and invasion, and induces the apoptosis of HepG2 and Bel7402 HCC cells through NF‑κB/Bcl-2, EGFR and EGFR downstream ERK/AKT signaling

The anticancer effects of the natural flavonoid, wogonin, have been reported. However, its molecular mechanisms of action have not yet been fully explored. In the present study, we aimed to examine the molecular mechanisms of action of wogonin and its effects on the biological behavior of the HepG2 and Bel7402 hepatocellular carcinoma (HCC) cell lines. We also examined the effects of wogonin on nuclear factor-κB (NF-κB)/Bcl-2 and epidermal growth factor receptor (EGFR) signaling, as well as on downstream pathways of EGFR, namely extracellular signal-regulated kinase (ERK)/AKT signaling. We found that treatment with wogonin inhibited the proliferation and invasion, and induced the apoptosis of the HepG2 and Bel7402 cells. In addition, treatment with wogonin decreased cyclin D1, cyclin E, CDK4/6, Bcl-2 and matrix metalloproteinase 2 (MMP2) expression, and promoted the cleavage of caspase-3 and caspase-9 in a concentration-dependent manner. Further experiments revealed that wogonin inhibited NF-κB/Bcl-2 signaling by decreasing the IκB and p65 phosphorylation levels. Wogonin also inhibited the activation of the EGFR (Tyr845) signaling pathway, and that of downstream pathways of EGFR, namely ERK/AKT/MMP2 signaling. The depletion of EGFR by siRNA partly abolished the inhibitory effects of wogonin on cyclin D1, MMP2 expression. On the whole, our our findings demonstrate that wogonin effectively suppresses the proliferation, invasion and survival of HCC cells through the modulation of the NF-κB and EGFR signaling pathways.

Transforming Nanomedicines From Lab Scale Production to Novel Clinical Modality

The use of nanoparticles as anticancer drug carriers has been studied for over 50 years. These nanoparticles that can carry drugs are now termed "nanomedicines". Since the approval of the first FDA "nanodrug", DOXIL in 1995, tremendous efforts have been made to develop hundreds of nanomedicines based on different materials. The development of drug nanocarriers (NCs) for cancer therapy is especially challenging and requires multidisciplinary approach. Not only is the translation from a lab scale production of the NCs to clinical scale a challenge, but tumor biology and its unique physiology also possess challenges that need to be overcome with cleverer approaches. Yet, with all the efforts made to develop new strategies to deliver drugs (including small molecules and biologics) for cancer therapy, the number of new NCs that are reaching clinical trials is extremely low. Here we discuss the reasons most of the NCs loaded with anticancer drugs are not likely to reach the clinic and emphasize the importance of understanding tumor physiology and heterogeneity, the use of predictive animal models, and the importance of sharing data as key denominators for potential successful translation of NCs from a bench scale into clinical modality for cancer care.

Multicomponent phytotherapeutic approach gaining momentum: Is the "one drug to fit all" model breaking down?

Natural product based drugs constitute a substantial proportion of the pharmaceutical market particularly in the therapeutic areas of infectious diseases and oncology. The primary focus of any drug development program so far has been to design selective ligands (drugs) that act on single selective disease targets to obtain highly efficacious and safe drugs with minimal side effects. Although this approach has been successful for many diseases, yet there is a significant decline in the number of new drug candidates being introduced into clinical practice over the past few decades. This serious innovation deficit that the pharmaceutical industries are facing is due primarily to the post-marketing failures of blockbuster drugs. Many analysts believe that the current capital-intensive model-"the one drug to fit all" approach will be unsustainable in future and that a new "less investment, more drugs" model is necessary for further scientific growth. It is now well established that many diseases are multi-factorial in nature and that cellular pathways operate more like webs than highways. There are often multiple ways or alternate routes that may be switched on in response to the inhibition of a specific target. This gives rise to the resistant cells or resistant organisms under the specific pressure of a targeted agent, resulting in drug resistance and clinical failure of the drug. Drugs designed to act against individual molecular targets cannot usually combat multifactorial diseases like cancer, or diseases that affect multiple tissues or cell types such as diabetes and immunoinflammatory diseases. Combination drugs that affect multiple targets simultaneously are better at controlling complex disease systems and are less prone to drug resistance. This multicomponent therapy forms the basis of phytotherapy or phytomedicine where the holistic therapeutic effect arises as a result of complex positive (synergistic) or negative (antagonistic) interactions between different components of a cocktail. In this approach, multicomponent therapy is considered to be advantageous for multifactorial diseases, instead of a "magic bullet" the metaphor of a "herbal shotgun" might better explain the state of affairs. The different interactions between various components might involve the protection of an active substance from decomposition by enzymes, modification of transport across membranes of cells or organelles, evasion of multidrug resistance mechanisms among others.

Synergistic inhibitory effect of wogonin and low-dose paclitaxel on gastric cancer cells and tumor xenografts

OBJECTIVE

To investigate the synergistic inhibitory effects of wogonin (WOG) and chemotherapeutic drugs on growth of gastric cancer cells and tumor xenografts.

METHODS

The IC50 values of WOG, cisplatin (CDDP) and paclitaxel (PTX) in four gastric cancer cell lines were determined by MTS assay. Hoechst staining and the median effect method of Chou-Talalay were used to assess the apoptosis of cells and the interaction of two drugs, respectively. BGC-823-derived xenografts in nude mice were established to investigate the effects of WOG combined with chemotherapeutic drugs in vivo.

RESULTS

WOG, CDDP and PTX inhibited the growth of BGC-823, MGC-803, MKN-45 and HGC-27 gastric cancer cells in a dose-dependent manner. WOG combined with CDDP or PTX synergistically inhibited the growth of all gastric cancer cell lines in vitro. In BGC-823, MGC-803, HGC-27 and MKN-45 cell lines, synergisms between WOG and PTX were shown when the fraction affected (Fa) values were <0.45, <0.90, <0.85 and <0.60. While WOG and CDDP had a synergistic inhibitory effect when the Fa values were >0, >0, >0.65 and >0.10. From the results of in vivo experiments using tumor xenografts, WOG and low-dose PTX showed better efficacy than either drug alone. The inhibitory percentages of tumor weight were 61.58%, 20.29%, and 22.28% for the combination, WOG-alone, and low-dose PTX-alone groups, respectively. Notably, WOG combined with CDDP displayed very high toxicity.

CONCLUSIONS

A synergistic inhibitory effect on growth was observed when WOG was combined with low-dose PTX in gastric cancer cells and tumor xenografts. These findings provide evidence for the design of a clinical trial to test the combination of WOG with low-dose PTX in human gastric cancer.

Wogonin attenuates etoposide-induced oxidative DNA damage and apoptosis via suppression of oxidative DNA stress and modulation of OGG1 expression

Damage to DNA can lead to many different acute and chronic pathophysiological conditions, ranging from cancer to endothelial damage. The current study has been initiated to determine whether the flavonoid wogonin can attenuate etoposide-induced oxidative DNA damage and apoptosis in mouse bone marrow cells. We found that oral administration of wogonin before etoposide injection significantly attenuates etoposide-induced oxidative DNA damage and apoptosis in a dose dependent manner. Etoposide induced a significant down-regulation of mRNA expression of the OGG1 repair gene and marked biochemical alterations characteristic of oxidative DNA stress, including increased 8-OHdG, enhanced lipid peroxidation and reduction in reduced glutathione. Prior administration of wogonin ahead of etoposide challenge restored these altered parameters. Importantly, wogonin had no antagonizing effect on etoposide-induce topoisomerase-II inhibition. Conclusively, our study indicates that wogonin has a protective role in the abatement of etoposide-induced oxidative DNA damage and apoptosis in the bone marrow cells of mice via suppression of oxidative DNA stress and enhancing DNA repair through modulation of OGG1 repair gene expression. Therefore, wogonin can be a promising chemoprotective agent and might be useful to avert secondary leukemia and other drug-related cancers in cured cancer patients and medical personnel exposing to the potent carcinogen etoposide.

Anti-cancer natural products isolated from chinese medicinal herbs

In recent years, a number of natural products isolated from Chinese herbs have been found to inhibit proliferation, induce apoptosis, suppress angiogenesis, retard metastasis and enhance chemotherapy, exhibiting anti-cancer potential both in vitro and in vivo. This article summarizes recent advances in in vitro and in vivo research on the anti-cancer effects and related mechanisms of some promising natural products. These natural products are also reviewed for their therapeutic potentials, including flavonoids (gambogic acid, curcumin, wogonin and silibinin), alkaloids (berberine), terpenes (artemisinin, β-elemene, oridonin, triptolide, and ursolic acid), quinones (shikonin and emodin) and saponins (ginsenoside Rg3), which are isolated from Chinese medicinal herbs. In particular, the discovery of the new use of artemisinin derivatives as excellent anti-cancer drugs is also reviewed.

Anti-cancer natural products isolated from chinese medicinal herbs

In recent years, a number of natural products isolated from Chinese herbs have been found to inhibit proliferation, induce apoptosis, suppress angiogenesis, retard metastasis and enhance chemotherapy, exhibiting anti-cancer potential both in vitro and in vivo. This article summarizes recent advances in in vitro and in vivo research on the anti-cancer effects and related mechanisms of some promising natural products. These natural products are also reviewed for their therapeutic potentials, including flavonoids (gambogic acid, curcumin, wogonin and silibinin), alkaloids (berberine), terpenes (artemisinin, β-elemene, oridonin, triptolide, and ursolic acid), quinones (shikonin and emodin) and saponins (ginsenoside Rg₃), which are isolated from Chinese medicinal herbs. In particular, the discovery of the new use of artemisinin derivatives as excellent anti-cancer drugs is also reviewed.

Wogonin potentiates the antitumor action of etoposide and ameliorates its adverse effects

Wogonin, a flavone in the roots of Scutellaria baicalensis, reduced etoposide-induced apoptotic cell death in normal cells, such as bone marrow cells and thymocytes. On the other hand, wogonin potentiated the proapoptotic or cytotoxic action of etoposide in tumor cells, such as Jurkat, HL-60, A549, and NCI-H226. These contradictory actions of wogonin on apoptosis are distinguished by normal or cancer cell types. Wogonin had no effect on apoptosis induced by other anticancer agents in the tumor cells. Thus, the potentiation effect of wogonin was observed only in etoposide-induced apoptosis in tumor cells. In a functional assay for P-glycoprotein (P-gp), wogonin suppressed excretion of calcein, a substrate for P-gp, in these tumor cells. Moreover, wogonin decreased the excretion of radiolabeled etoposide and accordingly increased intracellular content of this agent in the cells. P-gp inhibitors showed a similar potentiation effect on etoposide-induced apoptosis in these tumor cells. Thus, wogonin is likely to potentiate the anticancer action of etoposide due to P-gp inhibition and accumulation of this agent. These findings suggest that wogonin may be a useful chemotherapeutic adjuvant to potentiate the pharmacological action of etoposide and ameliorate its adverse effects.