Combined activity of oridonin and wogonin in advanced-stage ovarian cancer cells: Sensitivity of ovarian cancer cells to phyto-active chemicals

Exploring natural products as apoptosis modulators in cancers: insights into natural product-based therapeutic strategies

Cancer remains a leading cause of mortality globally, necessitating ongoing research and development of innovative therapeutic strategies. Natural products from plants, herbs, and marine species have shown great promise as anti-cancer therapies due to their bioactive components that alter cellular pathways, particularly apoptosis. This review explores the mechanism by which natural chemicals trigger the apoptosis of cancerous cells, which is crucial for eliminating them and halting tumor growth. These can affect the mitochondrial process by controlling the Bcl-2 protein family, increasing cytochrome c release, and activating caspases. They also activate death receptors like Fas and TRAIL to enhance the extrinsic apoptotic pathway. We focus on the main signaling channels involved, such as the endoplasmic reticulum (ER) stress-mediated apoptosis, extrinsic death receptor, and intrinsic mitochondrial pathways. The review explores the role of natural substances such as polyphenols, terpenoids, alkaloids, and flavonoids in promoting apoptotic cell death and increasing cancer cell susceptibility, potentially aiding in cancer treatments and the potential of combining natural products with traditional chemotherapeutic medicines to combat medication resistance and enhance therapeutic efficacy. Understanding cancer development involves inhibiting cell proliferation, regulating it, targeting apoptosis pathways, and using plant and marine extracts as apoptotic inducers.

Polyphenol-Based Prevention and Treatment of Cancer Through Epigenetic and Combinatorial Mechanisms

Polyphenols have been shown to be utilized as an effective treatment for cancer by acting as a DNMT or HDAC inhibitor, reducing inflammatory processes, and causing cell cycle arrest. While there have been many studies demonstrating the anti-cancerous potential of individual polyphenols, there are limited studies on the combinatorial effects of polyphenols. This review focuses on how combinations of different polyphenols can be used as a chemotherapeutic treatment option for patients. Specifically, we examine the combinatorial effects of three commonly used polyphenols: curcumin, resveratrol, and epigallocatechin gallate. These combinations have been shown to induce apoptosis, prevent colony formation and migration, increase tumor suppression, reduce cell viability and angiogenesis, and create several epigenetic modifications. In addition, these anti-cancerous effects were synergistic and additive. Thus, these findings suggest that using different combinations of polyphenols at the appropriate concentrations can be used as a better and more efficacious treatment against cancer as compared to using polyphenols individually.

Gross saponins of Tribulus terrestris attenuate rheumatoid arthritis by promoting apoptosis of fibroblast-like synoviocytes and reducing inflammation by inhibiting MAPK signalling pathway

Among the numerous treatment options for rheumatoid arthritis (RA), the promotion of synoviocyte apoptosis and inhibition of inflammation are considered the most effective. However, the potential pro-apoptotic effects of gross saponins of Tribulus terrestris (GSTT), which are natural saponins derived from the herb Tribulus terrestris L., on rheumatoid arthritis fibroblast-like synoviocytes (RA-FLSs) and their essential molecular mechanisms remain unclear. The aim of the present study was to investigate the influence of different concentrations of GSTT on RA-FLSs using various assays, including cell counting kit-8 (CCK-8), reverse transcription polymerase chain reaction (RT-PCR), enzyme-linked immunosorbent assay (ELISA), flow cytometry, terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL) and western blot analysis. These assessments were conducted to evaluate the cell viability, changes in the levels of inflammatory cytokines, apoptosis rates and alterations in protein expression related to this process. In vivo, arthritis clinical score, haematoxylin and eosin (HE) staining and ELISA were used to assess paw inflammation, histopathology and serum inflammatory cytokine changes. Our findings demonstrated that GSTT substantially promotes the apoptosis of RA-FLSs and reduces pro-inflammatory cytokine levels. GSTT also reduced the Bcl-2/Bax ratio and inhibited JNK and p38 phosphorylation. Furthermore, GSTT exhibits positive effects on RA by improving clinical scores, reducing synovial inflammatory infiltration and lowering serum pro-inflammatory cytokine levels. Therefore, by promoting the apoptosis of RA-FLSs and suppressing inflammation through the inhibition of the MAPK signalling pathway, GSTT is a promising therapeutic intervention for RA.

Wogonin induces mitochondrial apoptosis and synergizes with venetoclax in diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) is among the most aggressive hematological malignancies and patients are commonly treated with combinatorial immunochemotherapies such as R-CHOP. Till now, the prognoses are still variable and unsatisfactory, depending on the molecular subtype and the treatment response. Developing effective and tolerable new agents is always urgently needed, and compounds from a natural source have gained increasing attentions. Wogonin is an active flavonoid extracted from the traditional Chinese herbal medicine Scutellaria baicalensis Georgi and has shown extensive antitumor potentials. However, the therapeutic effect of wogonin on DLBCL remains unknown. Here, we found that treatment with wogonin dose- and time-dependently reduced the viability in a panel of established DLBCL cell lines. The cytotoxicity of wogonin was mediated through apoptosis induction, along with the loss of mitochondrial membrane potential and the downregulation of BCL-2, MCL-1, and BCL-xL. In terms of the mechanism, wogonin inhibited the PI3K and MAPK pathways, as evidenced by the clear decline in the phosphorylation of AKT, GSK3β, S6, ERK, and P38. Furthermore, the combination of wogonin and the BCL-2 inhibitor venetoclax elicited synergistically enhanced killing effect on DLBCL cells regardless of their molecular subtypes. Finally, administration of wogonin significantly impeded the progression of the DLBCL tumor in a xenograft animal model without obvious side effects. Taken together, the present study suggests a promising potential of wogonin in the treatment of DLBCL patients either as monotherapy or an adjuvant for venetoclax-based combinations.

A nanoscale natural drug delivery system for targeted drug delivery against ovarian cancer: action mechanism, application enlightenment and future potential

Ovarian cancer (OC) is one of the deadliest gynecological malignancies in the world and is the leading cause of cancer-related death in women. The complexity and difficult-to-treat nature of OC pose a huge challenge to the treatment of the disease, Therefore, it is critical to find green and sustainable drug treatment options. Natural drugs have wide sources, many targets, and high safety, and are currently recognized as ideal drugs for tumor treatment, has previously been found to have a good effect on controlling tumor progression and reducing the burden of metastasis. However, its clinical transformation is often hindered by structural stability, bioavailability, and bioactivity. Emerging technologies for the treatment of OC, such as photodynamic therapy, immunotherapy, targeted therapy, gene therapy, molecular therapy, and nanotherapy, are developing rapidly, particularly, nanotechnology can play a bridging role between different therapies, synergistically drive the complementary role of differentiated treatment schemes, and has a wide range of clinical application prospects. In this review, nanoscale natural drug delivery systems (NNDDS) for targeted drug delivery against OC were extensively explored. We reviewed the mechanism of action of natural drugs against OC, reviewed the morphological composition and delivery potential of drug nanocarriers based on the application of nanotechnology in the treatment of OC, and discussed the limitations of current NNDDS research. After elucidating these problems, it will provide a theoretical basis for future exploration of novel NNDDS for anti-OC therapy.

An iron-based metal-organic framework nanoplatform for enhanced ferroptosis and oridonin delivery as a comprehensive antitumor strategy

Ferroptosis is a recently discovered pathway for regulated cell death pathway. However, its efficacy is affected by limited iron content and intracellular ion homeostasis. Here, we designed a metal-organic framework (MOF)-based nanoplatform that incorporates calcium peroxide (CaO2) and oridonin (ORI). This platform can improve the tumor microenvironment and disrupt intracellular iron homeostasis, thereby enhancing ferroptosis therapy. Fused cell membranes (FM) were used to modify nanoparticles (ORI@CaO2@Fe-TCPP, NPs) to produce FM@ORI@CaO2@Fe-TCPP (FM@NPs). The encapsulated ORI inhibited the HSPB1/PCBP1/IREB2 and FSP1/COQ10 pathways simultaneously, working in tandem with Fe3+ to induce ferroptosis. Photodynamic therapy (PDT) guided by porphyrin (TCPP) significantly enhanced ferroptosis through excessive accumulation of reactive oxygen species (ROS). This self-amplifying strategy promoted robust ferroptosis, which could work synergistically with FM-mediated immunotherapy. In vivo experiments showed that FM@NPs inhibited 91.57% of melanoma cells within six days, a rate 5.6 times higher than chemotherapy alone. FM@NPs were biodegraded and directly eliminated in the urine or faeces without substantial toxicity. Thus, this study demonstrated that combining immunotherapy with efficient ferroptosis induction through nanotechnology is a feasible and promising strategy for melanoma treatment.

Oridonin from Rabdosia rubescens: An emerging potential in cancer therapy - A comprehensive review

Cancer incidences are rising each year. In 2020, approximately 20 million new cancer cases and 10 million cancer-related deaths were recorded. The World Health Organization (WHO) predicts that by 2024 the incidence of cancer will increase to 30.2 million individuals annually. Considering the invasive characteristics of its diagnostic procedures and therapeutic methods side effects, scientists are searching for different solutions, including using plant-derived bioactive compounds, that could reduce the probability of cancer occurrence and make its treatment more comfortable. In this regard, oridonin (ORI), an ent-kaurane diterpenoid, naturally found in the leaves of Rabdosia rubescens species, has been found to have antitumor, antiangiogenesis, antiasthmatic, antiinflammatory, and apoptosis induction properties. Extensive research has been performed on ORI to find various mechanisms involved in its anticancer activities. This review article provides an overview of ORI's effectiveness on murine and human cancer populations from 1976 to 2022 and provides insight into the future application of ORI in different cancer therapies.

Scutellaria baicalensis Georgi and Their Natural Flavonoid Compounds in the Treatment of Ovarian Cancer: A Review

Ovarian cancer (OC) is one of the most common types of cancer in women with a high mortality rate, and the treatment of OC is prone to high recurrence rates and side effects. Scutellaria baicalensis (SB) is a herbal medicine with good anti-cancer activity, and several studies have shown that SB and its flavonoids have some anti-OC properties. This paper elucidated the common pathogenesis of OC, including cell proliferation and cell cycle regulation, cell invasion and metastasis, apoptosis and autophagy, drug resistance and angiogenesis. The mechanisms of SB and its flavonoids, wogonin, baicalein, baicalin, Oroxylin A, and scutellarein, in the treatment of OC, are revealed, such as wogonin inhibits proliferation, induces apoptosis, inhibits invasion and metastasis, and increases the cytotoxicity of the drug. Baicalein also inhibits vascular endothelial growth factor (VEGF) expression etc. Analyzing their advantages and disadvantages in treating OC provides a new perspective on the role of SB and its flavonoids in OC treatment. It serves as a resource for future OC research and development.

Combination of Irinotecan and Melatonin with the Natural Compounds Wogonin and Celastrol for Colon Cancer Treatment

Colorectal cancers are one of the leading cancers worldwide and are known for their high potential for metastasis and resistance to therapy. The aim of this study was to investigate the effect of various combination therapies of irinotecan with melatonin, wogonin, and celastrol on drug-sensitive colon cancer cells (LOVO cell line) and doxorubicin-resistant colon cancer stem-like cells (LOVO/DX cell subline). Melatonin is a hormone synthesized in the pineal gland and is responsible for circadian rhythm. Wogonin and celastrol are natural compounds previously used in traditional Chinese medicine. Selected substances have immunomodulatory properties and anti-cancer potential. First, MTT and flow cytometric annexin-V apoptosis assays were performed to determine the cytotoxic effect and the induction of apoptosis. Then, the potential to inhibit cell migration was evaluated using a scratch test, and spheroid growth was measured. The results showed important cytotoxic effects of the drug combinations on both LOVO and LOVO/DX cells. All tested substances caused an increase in the percentage of apoptotic cells in the LOVO cell line and necrotic cells in the LOVO/DX cell subline. The strongest effect on the induction of cancer cell death was observed for the combination of irinotecan with celastrol (1.25 µM) or wogonin (50 µM) and for the combination of melatonin (2000 µM) with celastrol (1.25 µM) or wogonin (50 µM). Statistically significant improvements in the effect of combined therapy were found for the irinotecan (20 µM) and celastrol (1.25 µM) combination and irinotecan (20 µM) with wogonin (25 µM) in LOVO/DX cells. Minor additive effects of combined therapy were observed in LOVO cells. Inhibition of cell migration was seen in LOVO cells for all tested compounds, while only irinotecan (20 µM) and celastrol (1.25 µM) were able to inhibit LOVO/DX cell migration. Compared with single-drug therapy, a statistically significant inhibitory effect on cell migration was found for combinations of melatonin (2000 µM) with wogonin (25 µM) in LOVO/DX cells and irinotecan (5 µM) or melatonin (2000 µM) with wogonin (25 µM) in LOVO cells. Our research shows that adding melatonin, wogonin, or celastrol to standard irinotecan therapy may potentiate the anti-cancer effects of irinotecan alone in colon cancer treatment. Celastrol seems to have the greatest supporting therapy effect, especially for the treatment of aggressive types of colon cancer, by targeting cancer stem-like cells.

Oridonin and its derivatives for cancer treatment and overcoming therapeutic resistance

Cancer is one of the diseases with high morbidity and mortality on a global scale. Chemotherapy remains the primary treatment option for most cancer patients, including patients with progressive, metastatic, and recurrent diseases. To date, hundreds of chemotherapy drugs are used to treat various cancers, however, the anti-cancer efficacy and outcomes are largely hampered by chemotherapy-associated toxicity and acquired therapeutic resistance. The natural product (NP) oridonin has been extensively studied for its anti-cancer efficacy. More recently, oridonin has been shown to overcome drug resistance through multiple mechanisms, with yet-to-be-defined bona fide targets. Hundreds of oridonin derivative analogs (oridonalogs) have been synthesized and screened for improved potency, bioavailability, and other drug properties. Particularly, many of these oridonalogs have been tested against oridonin for tumor growth inhibition, potential for overcoming therapeutic resistance, and immunity modulation. This concise review seeks to summarize the advances in this field in light of identifying clinical-trial level drug candidates with the promise for treating progressive cancers and reversing chemoresistance.

Wogonin Increases Cisplatin Sensitivity in Ovarian Cancer Cells Through Inhibition of the Phosphatidylinositol 3-Kinase (PI3K)/Akt Pathway

Background

Wogonin (5,7-dihydroxy-8-methoxyflavone), one of flavonoids isolated from the Scutellaria baicalensis, has been regarded as an anticancer candidate because of its maximal efficacy in cancer cells. This study aimed to explore the possible mechanism that wogonin uses to enhance the sensitivity of ovarian cancer cells to cisplatin chemotherapy.

Material/Methods

The growth inhibition rates of ovarian cancer cells SKOV3/DDP and C13* were assessed by Cell Counting Kit-8 (CCK-8) assay. The apoptosis was assessed under a fluorescence microscope following staining with Hoechst. We further analyzed the expression of Bcl-2, cleaved caspases-3, cleaved-PARP, and phospho-Akt by western blotting.

Results

In the present study, we found that wogonin reduced proliferation of ovarian cancer cells SKOV3, SKOV3/DDP, OV2008, and C13* in dose- and time-dependent manners and it sensitized cisplatin-induced cytotoxicity. Moreover, treatment with wogonin also increased cisplatin-resistant SKOV3/DDP and C13* cells to low dose cisplatin-induced cell apoptosis. Additionally, such treatment resulted in a significant decrease in phosphorylated Akt.

Conclusions

Wogonin could significantly increase the sensitivity of cisplatin-resistant ovarian cancer cells to cisplatin by downregulating the PI3K/Akt pathway.

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.

Therapy Effects of Wogonin on Ovarian Cancer Cells

Background

Wogonin is a plant monoflavonoid and has been reported to induce apoptosis of cancer cells and show inhibitory effect on cancer cell growth. However, the detailed and underlying molecular mechanisms are not elucidated. In this study, we investigated the molecular and biological effects of wogonin in human ovarian A2780 cancer cells.

Materials and Methods

We determined the effects of wogonin on the changes of cell cycling and apoptotic responses of cells. Western blot analysis was used to measure the effects of wogonin on protein expressions.

Results

Our results showed that treatment with wogonin inhibited the cancer cell proliferation, decreased the percentage of G0/G1 subpopulation, and reduced invasiveness of A2780 cells. Exposure to wogonin also resulted in downregulated protein levels of estrogen receptor alpha (ER-α), VEGF, Bcl-2, and Akt and increased expressions of Bax and p53. In addition, exposure to wogonin increased caspase-3 cleavage and induced apoptosis in A2780 cells. Our study further showed that MPP, a specific ER-α inhibitor, significantly enhanced antitumor effects of wogonin in A2780 cells.

Conclusion

Our results suggest a potential clinical impact of wogonin on management of ovarian cancer.

The use of natural compounds for the targeting and chemoprevention of ovarian cancer

Among gynaecological cancers, ovarian cancer represents the leading cause of death in women. Current treatment for ovarian cancer entails surgery followed by combined chemotherapy with platinum and taxane, which are associated, particularly cisplatin, with severe side effects. While this treatment approach appears to be initially effective in a high number of patients, nearly 70% of them suffer a relapse within a few months after initial treatment. Therefore, more effective and better-tolerated treatment options are clearly needed. In recent years, several natural compounds (such as curcumin, epigallocatechin 3-gallate (EGCG), resveratrol, sulforaphane and Withaferin-A), characterized by long-term safety and negligible and/or inexistent side effects, have been proposed as possible adjuvants of traditional chemotherapy. Indeed, several in vitro and in vivo studies have shown that phytocompounds can effectively inhibit tumor cell proliferation, stimulate autophagy, induce apoptosis, and specifically target ovarian cancer stem cells (CSCs), which are generally considered to be responsible for tumor recurrence in several types of cancer. Here we review current literature on the role of natural products in ovarian cancer chemoprevention, highlighting their effects particularly on the regulation of inflammation, autophagy, proliferation and apoptosis, chemotherapy resistance, and ovarian CSC growth.

Geridonin, a novel derivative of oridonin, inhibits proliferation of MGC 803 cells both in vitro and in vivo through elevating the intracellular ROS

Objectives

To study the antitumour activity of a novel derivative of oridonin named geridonin in vitro and in vivo.

Methods

MTT and colony formation assay were used to test the cytotoxicity of geridonin; apoptosis, cell cycle arrest and the levels of reactive oxygen species were measured by flow cytometry; JC-1 staining assay was used to examine the mitochondrial membrane potential; the MGC 803 xenograft model was established to evaluate the antitumour effect of geridonin in vivo; H&E staining was performed for the histological analysis.

Key findings

In vitro, geridonin remarkably inhibited proliferation of gastrointestinal cancer cells including oesophageal, gastric, liver and colon cancers. On oesophageal, gastric cancer cells, geridonin displayed strong cytotoxicity than that of oridonin. In gastric cancer MGC 803 cells, geridonin triggered apoptosis through the mitochondrial pathway depending on caspase. In addition, geridonin sharply reduced the formation of cell colony, increased the intracellular levels of ROS and induced cell cycle arrest at G2/M phase. In vivo, geridonin delayed the growth of MGC 803 xenograft in athymic mice without obvious loss of bodyweight.

Conclusions

The novel derivative of oridonin, geridonin, inhibited the growth of human gastric cancer cells MGC 803 both in vitro and in vivo mainly via triggering apoptosis depending on elevating intracellular level of ROS.

Molecular Insight in the Multifunctional Effects of Oridonin

Oridonin has attracted considerable attention in the last decade because of its anti-cancer pharmacological properties. This ent-kaurane diterpenoid, isolated from the Chinese herb Rabdosia rubescens and some related species, has demonstrated great potential in the treatment profile of many diseases by exerting anti-tumor, anti-inflammatory, pro-apoptotic, and neurological effects. Unfortunately, the mechanisms via which oridonin exerts these effects remain poorly understood. This review provides an overview of the multifunctional effects of oridonin as well as the reasons for its potential for investigations in the treatment of many diseases other than cancer.

Advances of wogonin, an extract from Scutellaria baicalensis, for the treatment of multiple tumors

As the major bioactive compound of Scutellaria baicalensis that has been approved to be effective as an anti-inflammatory and antiviral inhibitor in cardiovascular diseases, wogonin (WG) showed potent and promising antitumor effects both in vitro and in vivo. It has been proved that WG has the ability to inhibit the growth of tumor cells, induce apoptosis, and suppress angiogenesis. The molecular mechanisms involve reactive oxygen species, Ca²⁺, NF-κB, tumor necrosis factor-related apoptosis-inducing ligand, and tumor necrosis factor-alpha. Furthermore, the synergistic effect of WG with 5-fluorouracil, etoposide, and adriamycin to enhance chemotherapy and reverse drug resistance has also been confirmed. In this review, we summarize the advances in recent years on the antitumor effect of WG on multiple tumors; in addition, we also present information regarding the synergistic and chemosensitizing effects of WG with other drugs to illustrate its potential use in the clinic.

BRCA1 185delAG Mutation Enhances Interleukin-1β Expression in Ovarian Surface Epithelial Cells

Familial history remains the strongest risk factor for developing ovarian cancer (OC) and is associated with germline BRCA1 mutations, such as the 185delAG founder mutation. We sought to determine whether normal human ovarian surface epithelial (OSE) cells expressing the BRCA1 185delAG mutant, BRAT, could promote an inflammatory phenotype by investigating its impact on expression of the proinflammatory cytokine, Interleukin-1β (IL-1β). Cultured OSE cells with and without BRAT were analyzed for differential target gene expression by real-time PCR, western blot, ELISA, luciferase reporter, and siRNA assays. We found that BRAT cells expressed increased cellular and secreted levels of active IL-1β. BRAT-expressing OSE cells exhibited 3-fold enhanced IL-1β mRNA expression, transcriptionally regulated, in part, through CREB sites within the (−1800) to (−900) region of its promoter. In addition to transcriptional regulation, BRAT-mediated IL-1β expression appears dualistic through enhanced inflammasome-mediated caspase-1 cleavage and activation of IL-1β. Further investigation is warranted to elucidate the molecular mechanism(s) of BRAT-mediated IL-1β expression since increased IL-1β expression may represent an early step contributing to OC.

Chinese medicines induce cell death: the molecular and cellular mechanisms for cancer therapy

Chinese medicines have long history in treating cancer. With the growing scientific evidence of biomedical researches and clinical trials in cancer therapy, they are increasingly accepted as a complementary and alternative treatment. One of the mechanisms is to induce cancer cell death. Aim. To comprehensively review the publications concerning cancer cell death induced by Chinese medicines in recent years and provide insights on anticancer drug discovery from Chinese medicines. Materials and Methods. Chinese medicines (including Chinese medicinal herbs, animal parts, and minerals) were used in the study. The key words including "cancer", "cell death", "apoptosis", "autophagy," "necrosis," and "Chinese medicine" were used in retrieval of related information from PubMed and other databases. Results. The cell death induced by Chinese medicines is described as apoptotic, autophagic, or necrotic cell death and other types with an emphasis on their mechanisms of anticancer action. The relationship among different types of cell death induced by Chinese medicines is critically reviewed and discussed. Conclusions. This review summarizes that CMs treatment could induce multiple pathways leading to cancer cell death, in which apoptosis is the dominant type. To apply these preclinical researches to clinic application will be a key issue in the future.

Wogonin reverses multi-drug resistance of human myelogenous leukemia K562/A02 cells via downregulation of MRP1 expression by inhibiting Nrf2/ARE signaling pathway

Constitutive NF-E2-related factor 2 (Nrf2) activation has been recently reported to play a pivotal role in enhancing cell survival and resistance to anticancer drugs in many tumors. Previously, much effort has been devoted to the investigation of blocking Nrf2 function in cultured cells and cancer tissues, but few researches have been undertaken to evaluate the precise mechanism of flavonoids-induced sensitivity by inhibiting Nrf2. In this study, we investigated the reversal effect of Wogonin, a flavonoid isolated from the root of Scutellaria baicalensis Georgi, in resistant human myelogenous leukemia. Data indicated that Wogonin had strong reversal potency by inhibiting functional activity and expression of MRP1 at both protein and mRNA in adriamycin (ADR)-induced resistant human myelogenous leukemia K562/A02 cells. Consequently, the inhibition of MRP1 by Wogonin was dependent on Nrf2 through the decreased binding ability of Nrf2 to antioxidant response element (ARE). Further research revealed Wogonin modulated Nrf2 through the reduction of Nrf2mRNA at transcriptional processes rather than RNA degradation, which is regulated by the PI3K/Akt pathway. Moreover, DNA-PKcs was found to be involved in the Wogonin-induced downregulation of Nrf2 mRNA at transcriptional levels. In summary, these results clearly demonstrated the effectiveness of using Wogonin via inhibiting Nrf2 to combat chemoresistance and suggested that Wogonin can be developed into an efficient natural sensitizer for resistant human myelogenous leukemia.

Targeting apoptosis pathways in cancer and perspectives with natural compounds from mother nature

Although the incidences are increasing day after day, scientists and researchers taken individually or by research group are trying to fight against cancer by several ways and also by different approaches and techniques. Sesquiterpenes, flavonoids, alkaloids, diterpenoids, and polyphenolic represent a large and diverse group of naturally occurring compounds found in a variety of fruits, vegetables, and medicinal plants with various anticancer properties. In this review, our aim is to give our perspective on the current status of the natural compounds belonging to these groups and discuss their natural sources, their anticancer activity, their molecular targets, and their mechanism of actions with specific emphasis on apoptosis pathways, which may help the further design and conduct of preclinical and clinical trials. Unlike pharmaceutical drugs, the selected natural compounds induce apoptosis by targeting multiple cellular signaling pathways including transcription factors, growth factors, tumor cell survival factors, inflammatory cytokines, protein kinases, and angiogenesis that are frequently deregulated in cancers and suggest that their simultaneous targeting by these compounds could result in efficacious and selective killing of cancer cells. This review suggests that they provide a novel opportunity for treatment of cancer, but clinical trials are still required to further validate them in cancer chemotherapy.

Selection for high oridonin yield in the Chinese medicinal plant Isodon (Lamiaceae) using a combined phylogenetics and population genetics approach

Oridonin is a diterpenoid with anti-cancer activity that occurs in the Chinese medicinal plant Isodon rubescens and some related species. While the bioactivity of oridonin has been well studied, the extent of natural variation in the production of this compound is poorly known. This study characterizes natural variation in oridonin production in order to guide selection of populations of Isodon with highest oridonin yield. Different populations of I. rubescens and related species were collected in China, and their offspring were grown in a greenhouse. Samples were examined for oridonin content, genotyped using 11 microsatellites, and representatives were sequenced for three phylogenetic markers (ITS, rps16, trnL-trnF). Oridonin production was mapped on a molecular phylogeny of the genus Isodon using samples from each population as well as previously published Genbank sequences. Oridonin has been reported in 12 out of 74 species of Isodon examined for diterpenoids, and the phylogeny indicates that oridonin production has arisen at least three times in the genus. Oridonin production was surprisingly consistent between wild-collected parents and greenhouse-grown offspring, despite evidence of gene flow between oridonin-producing and non-producing populations of Isodon. Additionally, microsatellite genetic distance between individuals was significantly correlated with chemical distance in both parents and offspring. Neither heritability nor correlation with genetic distance were significant when the comparison was restricted to only populations of I. rubescens, but this result should be corroborated using additional samples. Based on these results, future screening of Isodon populations for oridonin yield should initially prioritize a broad survey of all species known to produce oridonin, rather than focusing on multiple populations of one species, such as I. rubescens. Of the samples examined here, I. rubescens or I. japonicus from Henan province would provide the best source of oridonin.

Stimulation of suicidal erythrocyte death by oridonin

Oridonin triggers apoptosis of cancer cells and was suggested as anticancer agent. Oridonin is partially effective through mitochondrial depolarization and partially by modifying gene expression. Erythrocytes lack mitochondria and nuclei but may undergo eryptosis, a suicidal cell death characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine exposure at the cell surface. Triggers of eryptosis include increase of cytosolic Ca(2+)-activity, ATP depletion and ceramide formation. The present study explored, whether oridonin triggers eryptosis. Cytosolic Ca(2+)-concentration was estimated from Fluo3-fluorescence, cell volume from forward scatter in FACS analysis, phosphatidylserine exposure from binding of fluorescent annexin V, hemolysis from hemoglobin release, ATP concentration utilizing a luciferin-luciferase assay and ceramide abundance utilizing fluorescent anti-ceramide antibodies. A 48 h exposure to oridonin (≥25μM) significantly increased cytosolic Ca(2+)-concentration, increased ceramide formation, decreased forward scatter and triggered annexin V-binding (the latter in >20% of the erythrocytes). Oridonin didn't decrease ATP concentration and hemolysed <5% of erythrocytes. The effects of oridonin on annexin V binding were partially reversed in the nominal absence of Ca(2+) and by the addition of amiloride (1mM). The present observations reveal a completely novel effect of oridonin, i.e. triggering of Ca(2+) entry and ceramide formation as well as suicidal death of erythrocytes.