Baicalein, a novel apoptotic agent for hepatoma cell lines: a potential medicine for hepatoma

MSH2-MSH3 promotes DNA end resection during homologous recombination and blocks polymerase theta-mediated end-joining through interaction with SMARCAD1 and EXO1

DNA double-strand break (DSB) repair via homologous recombination is initiated by end resection. The extent of DNA end resection determines the choice of the DSB repair pathway. Nucleases for end resection have been extensively studied. However, it is still unclear how the potential DNA structures generated by the initial short resection by MRE11-RAD50-NBS1 are recognized and recruit proteins, such as EXO1, to DSB sites to facilitate long-range resection. We found that the MSH2-MSH3 mismatch repair complex is recruited to DSB sites through interaction with the chromatin remodeling protein SMARCAD1. MSH2-MSH3 facilitates the recruitment of EXO1 for long-range resection and enhances its enzymatic activity. MSH2-MSH3 also inhibits access of POLθ, which promotes polymerase theta-mediated end-joining (TMEJ). Collectively, we present a direct role of MSH2-MSH3 in the initial stages of DSB repair by promoting end resection and influencing the DSB repair pathway by favoring homologous recombination over TMEJ.

The Multifaceted Role of Baicalein in Cancer Management through Modulation of Cell Signalling Pathways

The roles of medicinal plants or their purified bioactive compounds have attracted attention in the field of health sciences due to their low toxicity and minimal side effects. Baicalein is an active polyphenolic compound, isolated from Scutellaria baicalensis, and plays a significant role in the management of different diseases. Epidemiologic studies have proven that there is an inverse association between baicalein consumption and disease severity. Baicalein is known to display anticancer activity through the inhibition of inflammation and cell proliferation. Additionally, the anticancer potential of baicalein is chiefly mediated through the modulation of various cell-signaling pathways, such as the induction of apoptosis, autophagy, cell cycle arrest, inhibition of angiogenesis, signal transducer and activator of transcription 3, and PI3K/Akt pathways, as well as the regulation of other molecular targets. Therefore, the current review aimed to explore the role of baicalein in different types of cancer along with mechanisms of action. Besides this, the synergistic effects with other anti-cancerous drugs and the nano-formulation based delivery of baicalein have also been discussed.

Deciphering the pharmacological mechanisms of Scutellaria baicalensis Georgi on oral leukoplakia by combining network pharmacology, molecular docking and experimental evaluations

BACKGROUND

Oral leukoplakia (OLK), an uncharacterized pathological condition that occurs as a white patch in the oral mucosa, is the most common precancerous condition. Scutellaria baicalensis Georgi (SBG) is a medicinal plant with a wide range of pharmacological effects. Increased evidence shows that SBG has potential therapeutic effects on OLK. However, the therapeutic mechanisms of SBG against OLK have not yet been completely elucidated.

PURPOSE

This study aimed to clarify the active components and multi-target mechanisms of SBG against OLK via network pharmacology, molecular docking and experimental evaluations.

STUDY DESIGN AND METHODS

The active components and related targets of SBG were screened by the TCMSP database and Swiss Target Prediction database. Potential therapeutic targets of OLK were collected using the GeneCards and OMIM databases. Then, we established protein-protein interaction (PPI), compound-target-disease (C-T-D), and compound-target-pathway (C-T-P) networks by Cytoscape to identify the main components, core targets, and pharmacological pathways of SBG against OLK via applying data mining techniques and topological parameters. Metascape database was utilized for GO and KEGG pathway analysis. Molecular docking techniques were used to estimate the binding force between the components and the hub genes. Subsequently, a series of in vitro experiments, specifically CCK-8 assay, clone formation assay, wound healing assay, flow cytometry, RT-qPCR and western blotting were conducted for further verification.

RESULTS

There were 25 active components and 31 related target genes in SBG against OLK. PPI analysis showed that Akt1, VEGFA, EGFR, HIF1A and PTGS2 shared the highest centrality among all target genes. KEGG pathway analysis found that PI3K-Akt signaling pathway may occupy core status in the anti-OLK system. Molecular docking results showed that the main active components of SBG had a strong binding affinity to the hub genes. In vitro experiments showed that the leading component baicalein may inhibit proliferation, block cells in the S phase, induce DOK cell apoptosis, and downregulate the mRNA expression of 5 hub genes by inhibiting PI3K/Akt signaling pathway activation.

CONCLUSION

The most predominant component of SBG against OLK was baicalein and the key pathway was PI3K/Akt. The main components and hub genes had robust binding abilities. In vitro experiments showed that baicalein could inhibit the proliferation of DOK cells, induce apoptosis, block the cell cycle, and inhibit the mRNA expression level of the hub genes by inhibiting the PI3K/Akt pathway.

Cogent role of flavonoids as key orchestrators of chemoprevention of hepatocellular carcinoma: A review

Chemopreventive approaches with food-derived phytochemicals are progressively rising as a significant aspect of tumor management and control. Herein, we have showcased the major phytoconstituents belonging to the group of flavanoid, as anti-cancer agents used for the treatment and prevention of hepatocellular carcinoma (HCC). Sorafenib is the sole drug used for the treatment of advanced HCC, but its clinical application is limited because of its severe adverse effects and drug resistance. Diet-based chemoprevention seems to be the way forward for this disease of malignant nature. As HCC is derived from a chronic inflammatory milieu, the regular incorporation of bioactive phytochemicals in the diet will confer protection and prevent progression to hepatocarcinogenesis. Many preclinical studies proved that the health benefits of flavonoids confer cytotoxic potential against various types of cancers including hepatocellular carcinoma. As flavonoids with excellent safety profile are abundantly present in common vegetables and fruits, they can be better utilized for chemoprevention and chemosensitization in such chronic condition. This review highlights the plausible role of the eight most promising flavonoids (Curcumin, Kaempferol, Resveratrol, Quercetin, Silibinin, Baicalein, Galangin and Luteolin) as key orchestrators of chemoprevention in hepatocellular carcinoma with preclinical and clinical evidence. An attempt to address the challenges in its clinical translation is also included. This review also provides an insight into the close association of HCC and metabolic disorders which may further decipher the chemopreventive effect of dietary bioactive from a proof of concept to extensive clinical translation. PRACTICAL APPLICATIONS: According to GLOBOCAN 2020 database, it is estimated that 905,677 new cases of liver cancer and approximately 830,180 deaths related to that. The cancer incidence and mortality are almost similar as it is diagnosed at an advanced stage in patients where systemic drug therapy is the sole approach. Due to the emergence of multidrug resistance and drug-related toxicities, most of the patient can not adhere to the therapy regimen. Flavonoids are known to be a potential anticancer agent with an excellent safety profile. These are found to be effective preclinically against hepatocellular carcinoma through modulation of numerous pathways in hepatocarcinogenesis. But, the bioavailability issue, lack of well designed-validated clinical evidence, the possibility of food-drug interaction etc limit its clinical utility. The research inputs mainly to overcome pharmacokinetic issues along with suitable validation of efficacy and toxicity will be a critical point for establishing flavonoids as an effective, safe, affordable therapeutics.

Baicalein Induces Apoptosis of Pancreatic Cancer Cells by Regulating the Expression of miR-139-3p and miR-196b-5p

Pancreatic cancer is a common malignant tumor with a high incidence and mortality rate. The prognosis of patients with pancreatic cancer is considerably poor due to the lack of effective treatment in clinically. Despite numerous studies have revealed that baicalein, a natural product, is responsible for suppressing multiple cancer cells proliferation, motility and invasion. The mechanism by which baicalein restraining pancreatic cancer progression remains unclear. In this study, we firstly verified that baicalein plays a critical role in inhibiting pancreatic tumorigenesis in vitro and in vivo. Then we analyzed the alteration of microRNAs (miRNAs) expression levels in Panc-1 cells incubated with DMSO, 50 and 100 μM baicalein by High-Throughput sequencing. Intriguingly, we observed that 20 and 39 miRNAs were accordingly up- and down-regulated through comparing Panc-1 cells exposed to 100 μM baicalein with the control group. Quantitative PCR analysis confirmed that miR-139-3p was the most up-regulated miRNA after baicalein treatment, while miR-196b-5p was the most down-regulated miRNA. Further studies showed that miR-139-3p induced, miR-196b-5p inhibited the apoptosis of Panc-1 cells via targeting NOB1 and ING5 respectively. In conclusion, we demonstrated that baicalein is a potent inhibitor against pancreatic cancer by modulating the expression of miR-139-3p or miR-196b-5p.

Baicalein Inhibits Gastric Cancer Cell Proliferation and Migration through a FAK Interaction via AKT/mTOR Signaling

Gastric cancer is a common malignancy worldwide and is associated with high morbidity and mortality rates. However, very little is known about the underlying mechanism in human gastric cancer cells. Baicalein (BAI), a widely used Chinese herbal medicine, has shown anticancer effects on many types of human cancer cell lines. Here, we investigated the molecular mechanisms underlying BAI action on gastric cancer cell proliferation and migration. The results showed that BAI can expressively inhibit cell proliferation, colony-forming ability and migration ability in a dose-dependent manner, while in the meantime inducing cell apoptosis. Additionally, we found that BAI can suppress FAK and the phosphorylation of PI3K, AKT and mTOR in a dose-dependent manner. Furthermore, BAI significantly inhibited tumor growth in a xenograft model. Also, BAI can inhibit the proliferation and migration of gastric cancer cells and the expression of the pathway by downregulating the expression of FAK. In short, we demonstrated that BAI inhibited gastric cancer cell proliferation and migration through FAK interaction via downregulation in AKT/mTOR signaling, which signifies that BAI may be a latent therapeutic factor for the treatment of gastric cancer patients and that FAK might be a hopeful therapy target for the disease.

Traditional Chinese medicine combined with hepatic targeted drug delivery systems: A new strategy for the treatment of liver diseases

Liver diseases are clinically common and present a substantial public health issue. Many of the currently available drugs for the treatment of liver diseases suffer from limitations that include low hepatic distribution, lack of target effects, poor in vivo stability and adverse effects on other organs. Consequently, conventional treatment of hepatic diseases is ineffective. TCM is commonly used in the treatment of liver diseases worldwide, particularly in China, and has advantages over conventional therapy. HTDDS can be designed to enhance clinical efficacy in the treatment of liver diseases. We have conducted an extensive review of 335 studies reported since 1964. These included about 166 references involving the treatment of liver diseases with TCM (covering active components of TCM, single TCM and Chinese medicine formulas), 169 reports on HTDDS and background studies on liver-related diseases. Here we review the long history of TCM in the treatment of liver diseases.We have also reviewed the status of studies on active components of TCM using nanotechnology-based targeted delivery systems to provide support for further research and development of TCM-based targeted preparations for the treatment of liver disease.

Network Pharmacology and Bioinformatics Approach Reveals the Therapeutic Mechanism of Action of Baicalein in Hepatocellular Carcinoma

Liver cancer is the fourth leading cause of cancer death worldwide, and hepatocellular carcinoma (HCC) accounts for the greatest proportion of these deaths. Baicalein, a flavonoid isolated from the root of Scutellariae radix, is considered a potential candidate to treat HCC. However, the underlying molecular mechanisms remain poorly understood. In the present study, a network pharmacological approach was combined with microarray data (GSE95504) acquired from the Gene Expression Omnibus database to reveal the therapeutic mechanisms of action of baicalein at a systemic level. We identified 38 baicalein targets and 76 differently expressed genes (DEGs) following treatment with baicalein, including 55 upregulated and 21 downregulated genes. The DEGs were significantly enriched in the biological functions of apoptosis, endoplasmic reticulum stress, and PERK-mediated unfolded protein response. Protein-protein interaction (PPI) network construction and topological screening revealed a core module of PPIs including two baicalein targets, TP53 and CDK1, and two downregulated DEGs, HSPA1A and HSPA1B. Expression and survival data for these genes in the module derived from Gene Expression Profiling Interactive Analysis (GEPIA) were subjected to Kaplan–Meier analysis of overall survival and disease-free survival. Overexpression of CDK1, BRCA1, TUBB, HSPA1A, HSPA1B, and HSPA4 was associated with significantly worse overall survival, while overexpression of CDK1, CLU7, BRCA1, and TUBB was associated with significantly worse disease-free survival. These data suggest that baicalein exerts therapeutic effects against HCC via a PPI network involving TP53, CDK1, HSPA1A, and HSPA1B.

Dual-function of Baicalin in nsPEFs-treated Hepatocytes and Hepatocellular Carcinoma cells for Different Death Pathway and Mitochondrial Response

Nanosecond pulsed electric fields (nsPEFs) is emerged as a potential curative modality to ablate hepatocellular carcinoma (HCC). The application of local ablation is usually limited by insufficiency of liver function. While baicalin, a flavonoid isolated from Scutellaria baicalensis Georgi, has been proven to possess both anti-tumor and protective effects. Our study aimed to estimate different responses of hepatic cancer cells and hepatocytes to the combination of nsPEFs and baicalin. Cell viability, apoptosis and necrosis, mitochondrial transmembrane potential (MTP) and reactive oxygen species (ROS) were examined by CCK-8, FCM, JC-1 and fluorescent probe, respectively. After treatment by nsPEFs, most hepatocytes died by apoptosis, nevertheless, nearly all cancer cells were killed through necrosis. Low concentration of baicalin synergically enhanced nsPEFs-induced suppression and necrosis of HCC cells, nevertheless, the application of baicalin protected normal hepatocytes from the injury caused by nsPEFs, owing to elevating mitochondrial transmembrane potential and reducing ROS generation. Our work provided an advantageous therapy for HCC through the enhanced combination treatment of nsPEFs and baicalin, with which could improve the tumor-ablation effect and alleviate the injury of hepatic tissues simultaneously.

Baicalein induces apoptosis and autophagy of breast cancer cells via inhibiting PI3K/AKT pathway in vivo and vitro

Purpose

Baicalein, a widely used Chinese herbal medicine, has shown anticancer effects on many types of human cancer cell lines. However, little is known about the underlying mechanism in human breast cancer cells. In this study, we examined the apoptotic and autophagic pathways activated following baicalein treatment in human breast cancer cells in vitro and in vivo.

Materials and methods

In in vitro study, we used MTT and clone formation assay to confirm the inhibitory role of baicalein on proliferation of MCF-7 and MDA-MB-231 breast cancer cells. Apoptosis was detected employing Hoechst 33258 staining, JC-1 staining, and flow cytometry. Autophagy was monitored by acridine orange staining and transmission electron microscopy observation. Quantitative real-time PCR and Western blot analysis were employed to study the effects of baicalein on PI3K/AKT signaling components of MCF-7 and MDA-MB-231 breast cancer cells. In in vivo study, the effect of baicalein was tested with a breast cancer cells transplantation tumor model.

Results

Our study showed that baicalein has the potential to suppress cell proliferation, induce apoptosis and autophagy of breast cancer cells in vitro and in vivo. Furthermore, baicalein significantly downregulated the expression of p-AKT, p-mTOR, NF-κB, and p-IκB while enhancing the expression of IκB in MCF-7 and MDA-MB-231 cells. It also decreased the p-AKT/AKT and p-mTOR/mTOR ratios.

Conclusion

Our study demonstrated that baicalein induces apoptosis and autophagy of breast cancer cells via inhibiting the PI3K/AKT signaling pathway in vivo and vitro. Our study revealed that baicalein may be a potential therapeutic agent for breast cancer.

Anticancer Effects of Baicalein in Pancreatic Neuroendocrine Tumors In Vitro and In Vivo

OBJECTIVES

Baicalein is a Chinese traditional medicine that inhibits tumor migration and growth. Pancreatic neuroendocrine tumors (pNETs) have a high incidence in China, but there are still no effective treatments. The aim of our study was to investigate whether baicalein could inhibit pNETs.

METHODS

In vitro, we used BON1-a cell line of pNETs-to analyze the apoptosis and migration and invasion after baicalein treatment via flow cytometry and Western blot. In vivo, we used a xenograft tumors model to evaluate the size of tumors after baicalein treatment. Western blot was used to analyze the expression of apoptosis and migration-related protein.

RESULTS

In vitro, the Cell Counting Kit 8 assay showed that baicalein decreased BON1 viability, and flow cytometry demonstrated that baicalein induced BON1 apoptosis and protein changes. In addition, baicalein inhibited BON1 migration and invasion as shown via a Transwell assay. In vivo, baicalein inhibited tumor growth and migration and also increased apoptosis-related protein expression.

CONCLUSIONS

Baicalein could increase caspase-3 and Bax expression and decrease survivin and Bcl-2 to induce apoptosis. It inhibits migration and invasion by decreasing expression of vascular endothelial growth factor and matrix metalloproteinases 2 and 9.

Baicalein attenuates α-synuclein aggregation, inflammasome activation and autophagy in the MPP+-treated nigrostriatal dopaminergic system in vivo

ETHNOPHARMACOLOGICAL RELEVANCE

Neuroinflammation, oxidative stress, and protein aggregation form a vicious cycle in the pathophysiology of Parkinson's disease (PD); activated microglia is the main location of neuroinflammation. A Chinese medicine book, "Shanghan Lun", known as the "Treatises on Cold damage Diseases" has suggested that Scutellaria baicalensis Georgi is effective in treating CNS diseases. The anti-inflammatory mechanisms of baicalein, a phenolic flavonoid in the dried root of Scutellaria baicalensis Georgi, remain to be explored.

AIM OF THE STUDY

The neuroprotective mechanisms of baicalein involving α-synuclein aggregation, inflammasome activation, and programmed cell death were investigated in the nigrostriatal dopaminergic system of rat brain in vivo.

MATERIALS AND METHODS

Intranigral infusion of 1-methyl-4-phenylpyridinium (MPP⁺, a Parkinsonian neurotoxin) was performed on anesthetized Sprague-Dawley rats. Baicalein was daily administered via intraperitoneal injection. Striatal dopamine levels were measured using high performance liquid chromatography coupled with electrochemical detection. Cellular signalings were measured by Western blot assay, immunofluorescent staining assay and enzyme-linked immunosorbent assay.

RESULTS

Systemic administration of baicalein attenuated MPP⁺-induced reductions in striatal dopamine content and tyrosine hydroxylase (a biomarker of dopaminergic neurons) in the infused substantia nigra (SN). Furthermore, MPP⁺-induced elevations in α-synuclein aggregates (a pathological hallmark of PD), ED-1 (a biomarker of activated microglia), activated caspase-1 (a proinflammatory caspase), IL-1β and cathepsin B (a cysteine lysosomal protease) in the infused SN were attenuated in the baicalein-treated rats. Moreover, intense immunoreactivities of caspase 1 and cathepsin B were co-localized with that of ED-1 in the MPP⁺-infused SN. At the same time, baicalein inhibited MPP⁺-induced increases in active caspases 9 and 12 (biomarkers of apoptosis) as well as LC3-II levels (a biomarker of autophagy) in the rat nigrostriatal dopaminergic system.

CONCLUSION

Our in vivo study showed that baicalein possesses anti-inflammatory activities by inhibiting α-synuclein aggregation, inflammasome activation and cathepsin B production in the MPP⁺-infused SN. Moreover, baicalein is of therapeutic significance because it inhibits MPP⁺-induced apoptosis and autophagy in the nigrostriatal dopaminergic system of rat brain.

Baicalein Inhibits Epithelial to Mesenchymal Transition via Downregulation of Cyr61 and LOXL-2 in MDA-MB231 Breast Cancer Cells

Epithelial-mesenchymal transition (EMT) is a critical step in the acquisition of the migratory and invasive capabilities associated with metastatic competence. Cysteine-rich protein 61 (CCN1/Cyr61) has been implicated as an important mediator in the proliferation and metastasis of breast cancer. Hence, Cyr61 and associated pathways are attractive targets for therapeutic interventions directed against the EMT. In the present study, we report that baicalein significantly inhibits the expression of Cyr61 and migration and invasion of MDA-MB231 human breast cancer cells. Exposure to baicalein led to increased E-cadherin expression, possibly due to the ubiquitination of Snail and Slug, which was mediated by the Cyr61/Akt/glycogen synthase kinase 3β (GSK3β) pathway. Further analysis revealed that baicalein inhibited the expression of lysyl oxidase like-2 (LOXL-2), which is a functional collaborator of Snail and Slug, and subsequently attenuated the direct interaction between LOXL-2 and Snail or Slug, thereby enhancing GSK3β-dependent Snail and Slug degradation. Our findings provide new insights into the antimetastatic mechanism of baicalein and may contribute to its beneficial use in breast cancer therapies.

Anticancer properties of baicalein: a review

The constituents of many traditional Chinese herbal remedies are currently at the forefront of modern cancer research. Baicalein, a bioactive flavone widely used in nutraceuticals and pharmaceuticals, has shown great potential in the treatment and prevention of cancer without causing severe side effects. Baicalein induces cancer cell apoptosis and cause cell cycle arrest. It shows inhibitory effects on angiogenesis, metastasis and inflammation, all of which are necessary for the promotion and progression of cancer. This review presents an overview of the anti-cancer effects and mechanisms of baicalein. In addition, the bioavailability of baicalein and approaches to improve it are summarized. Treatments of baicalein in combination with other anti-cancer agents are also mentioned.

A Novel Chemotherapeutic Agent to Treat Tumors with DNA Mismatch Repair Deficiencies

Impairing the division of cancer cells with genotoxic small molecules has been a primary goal to develop chemotherapeutic agents. However, DNA mismatch repair (MMR)-deficient cancer cells are resistant to most conventional chemotherapeutic agents. Here we have identified baicalein as a small molecule that selectively kills MutSα-deficient cancer cells. Baicalein binds preferentially to mismatched DNA and induces a DNA damage response in a MMR-dependent manner. In MutSα-proficient cells, baicalein binds to MutSα to dissociate CHK2 from MutSα leading to S-phase arrest and cell survival. In contrast, continued replication in the presence of baicalein in MutSα-deficient cells results in a high number of DNA double-strand breaks and ultimately leads to apoptosis. Consistently, baicalein specifically shrinks MutSα-deficient xenograft tumors and inhibits the growth of AOM-DSS-induced colon tumors in colon-specific MSH2 knockout mice. Collectively, baicalein offers the potential of an improved treatment option for patients with tumors with a DNA MMR deficiency. Cancer Res; 76(14); 4183-91. ©2016 AACR.

The Traditional Chinese Medicine Baicalein Potently Inhibits Gastric Cancer Cells

Baicalein, a traditional Chinese medicine, is a member of the flavone subclass of flavonoids. It has been reported to have anticancer activities in several human cancer cell lines in vitro. However, the therapeutic effects of baicalein on human gastric cancer and the mechanisms of action of baicalein have not been extensively studied. In the present study, we utilized a cell viability assay and an in vivo tumor growth assay to test the inhibitory effects of baicalein on gastric cancer. Analyses of the cell cycle, apoptosis and alterations in protein levels were performed to elucidate how baicalein functions in gastric cancer. We found that baicalein could potently inhibit gastric cancer cell growth and colony formation. Baicalein robustly induced arrest at the S phase in the gastric cancer cell line SGC-7901. It induced SGC-7901 cell apoptosis and disrupted the mitochondrial membrane potential (ΔΨm) in a dose-dependent manner. Analysis of protein expression levels in SGC-7901 cells showed downregulation of Bcl-2 and upregulation of Bax in response to baicalein treatment. These results indicate that baicalein induces apoptosis of gastric cancer cells through the mitochondrial pathway. In an in vivo subcutaneous xenograft model, baicalein exhibited excellent tumor inhibitory effects. These results indicate that baicalein may be a potential drug for gastric cancer therapy.

BA-j as a novel CDK1 inhibitor selectively induces apoptosis in cancer cells by regulating ROS

Cyclin-dependent kinase 1 (CDK1) is the only necessary CDK in cell proliferation and a novel target in the development of anticancer drugs. 8-Hydroxypiperidinemethyl-baicalein (BA-j) is a novel selective CDK1 inhibitor with broad spectrum anti-cancer activity (IC₅₀ 12.3 μM) and 2 tumor xenografts. Because of the differential mechanisms controlling redox-states in normal and cancer cells, BA-j can capture oxygen free radicals (^·O₂⁻) and selectively increase the level of H₂O₂ in cancer cells, thereby specifically oxidize and activate the intrinsic apoptosis pathway bypassing the extrinsic death receptor pathway, thus inducing apoptosis in cancer cells rather than in normal cells. BA-j is different from cytotoxic anticancer drugs which can activate both the intrinsic apoptosis pathway and the extrinsic death receptor pathway, and therefore harm normal cells while killing cancer cells. The molecular and biochemical mechanisms of reactive oxygen species (ROS) regulation suggest that BA-j may be developed into a novel anticancer agent.

Cytotoxicity of dietary flavonoids on different human cancer types

Flavonoids are ubiquitous in nature. They are also in food, providing an essential link between diet and prevention of chronic diseases including cancer. Anticancer effects of these polyphenols depend on several factors: Their chemical structure and concentration, and also on the type of cancer. Malignant cells from different tissues reveal somewhat different sensitivity toward flavonoids and, therefore, the preferences of the most common dietary flavonoids to various human cancer types are analyzed in this review. While luteolin and kaempferol can be considered as promising candidate agents for treatment of gastric and ovarian cancers, respectively, apigenin, chrysin, and luteolin have good perspectives as potent antitumor agents for cervical cancer; cells from main sites of flavonoid metabolism (colon and liver) reveal rather large fluctuations in anticancer activity probably due to exposure to various metabolites with different activities. Anticancer effect of flavonoids toward blood cancer cells depend on their myeloid, lymphoid, or erythroid origin; cytotoxic effects of flavonoids on breast and prostate cancer cells are highly related to the expression of hormone receptors. Different flavonoids are often preferentially present in certain food items, and knowledge about the malignant tissue-specific anticancer effects of flavonoids could be purposely applied both in chemoprevention as well as in cancer treatment.

Comparison of free radical formation induced by baicalein and pentamethyl-hydroxychromane in human promyelocytic leukemia cells using electron spin resonance

Baicalein and pentamethyl-hydroxychromane (PMC) have been investigated for use as antioxidants. However, antioxidants may stimulate free radical formation under certain conditions. The aim of our study was to determine whether PMC and baicalein exhibit both pro-oxidant and antioxidant activities in human promyelocytic leukemia (HL-60) cells. In this study, electron spin resonance spectrometry was used to investigate the effects of baicalein and PMC on free radical formation. In HL-60 cells, baicalein and PMC produced hydroxyl and phenoxyl radicals, respectively, but each inhibited radical formation by the other. The PMC pro-oxidant activity required H₂O₂, whereas baicalein produced hydroxyl radicals during the cell resting state only. The antioxidant effect of baicalein on PMC-induced oxidative stress in HL-60 cells may involve myeloperoxidase inhibition, which produces the myeloperoxidase-protein radical. Our investigation of the antioxidant effects of baicalein on arachidonic acid (AA)-induced oxidative stress in HL-60 cells showed that the baicalein-phenoxyl radical was the primary product, and that either carbon-centered or acyl radicals were the secondary products. However, the antioxidant effects of PMC on AA-induced oxidative stress produced only nonradical products. In conclusion, we showed that baicalein displayed both pro-oxidant and antioxidant activities in HL-60 cells. PMC exhibited no pro-oxidant activity during the cells’ resting state but produced the PMC-phenoxyl radical in the presence of H₂O₂. The reaction of baicalein with AA in HL-60 cells produced baicalein-derived phenoxyl radicals that may initiate various pro-oxidative reactions. However, PMC does not produce radicals when it acts as an antioxidant. Thus, PMC is more beneficial as an antioxidant than baicalein.

dTGS: Method for Effective Components Identification from Traditional Chinese Medicine Formula and Mechanism Analysis

Because of the complexity of the components in Traditional Chinese Medicine formula (TCM formula), it is still a challenge to identify its effective components, to elucidate the mechanism of the components, and to discover the relationship between components and therapy objectives. In this paper, a method called directed TCM grammar systems (dTGS) for effective component identification was proposed using entity grammar systems (EGS) as the theoretical framework. The component-disease relationship of a TCM formula (i.e., Bai-Hu decoction plus Wasting-Thirsting formula, BHDWT) and one disease (i.e., type 2 diabetes mellitus) treated with it was studied, and the effective component groups (ECGs) were identified. 19 compounds were found acting on 20 proteins in type 2 diabetes mellitus (T2D) disease network, and 15 compounds were determined as the candidate effective components. Results indicated that this method can be used to identify the effective components and provide an innovative way to elucidate the molecular mechanism of TCM formulas.

Baicalein inhibits the invasion and metastatic capabilities of hepatocellular carcinoma cells via down-regulation of the ERK pathway. PLoS One. 2013;8:e72927. [PMID: 24039823 PMCID: PMC3765161 DOI: 10.1371/journal.pone.0072927]

Baicalein, a widely used Chinese herbal medicine, has historically been used in anti-inflammatory and anti-cancer therapies. However, the anti-metastatic effect and molecular mechanism(s) of baicalein on hepatocellular carcinoma (HCC) remain poorly understood. Therefore, the purpose of this study was to assess the anti-metastatic effects of baicalein and related mechanism(s) on HCC. Based on assays utilized in both HCC cell lines and in an animal model, we found that baicalein inhibited tumor cell metastasis in vivo and in vitro. Furthermore, after treatment with baicalein for 24 hours, there was a decrease in the levels of matrix metalloproteinase-2 (MMP-2), MMP-9 and urokinase-type plasminogen activator (u-PA) expression as well as proteinase activity in hepatocellular carcinoma MHCC97H cells. Meanwhile, the expression of tissue inhibitor of metalloproteinase-1 (TIMP-1) and TIMP-2 were increased in a dose-dependent fashion. Moreover, baicalein treatment dramatically decreased the levels of the phosphorylated forms of MEK1 and ERK1/2. MEK1 overexpression partially blocked the anti-metastatic effects of baicalein. Combined treatment with an ERK inhibitor (U0126) and baicalein resulted in a synergistic reduction in MMP-2, MMP-9 and u-PA expression and an increase in TIMP-1 and TIMP-2 expression; the invasive capabilities of MHCC97H cells were also inhibited. In conclusion, baicalein inhibits tumor cell invasion and metastasis by reducing cell motility and migration via the suppression of the ERK pathway, suggesting that baicalein is a potential therapeutic agent for HCC.

Baicalein Triggers Mitochondria-Mediated Apoptosis and Enhances the Antileukemic Effect of Vincristine in Childhood Acute Lymphoblastic Leukemia CCRF-CEM Cells

Acute lymphoblastic leukemia (ALL) accounts for approximately 75% of childhood leukemia, and chemotherapy remains the mainstay therapy. Baicalein is an active flavonoid used in traditional Chinese medicine and has recently been found to have anticancer, anti-inflammatory, and antiallergic properties. This study aims to investigate the molecular apoptotic mechanisms of baicalein in CCRF-CEM leukemic cells and to evaluate the combined therapeutic efficacy of baicalein with several commonly used chemotherapeutic drugs in CCRF-CEM cells. Our results demonstrate that baicalein induces mitochondria-dependent cleavage of caspases-9 and -3 and PARP with concomitant decreases in IAP family proteins, survivin, and XIAP. Furthermore, our results present for the first time that baicalein triggers a convergence of the intrinsic and extrinsic apoptotic pathways via the death receptor-caspase 8-tBid signaling cascade in CCRF-CEM cells. In addition, we also present for the first time that the combination of baicalein and vincristine results in a synergistic therapeutic efficacy. Overall, this combination strategy is recommended for future clinical trials in the treatment of pediatric leukemia owing to baicalein's beneficial effects in alleviating the vomiting, nausea, and skin rashes caused by chemotherapy.

Baicalein induces apoptosis in esophageal squamous cell carcinoma cells through modulation of the PI3K/Akt pathway

Baicalein, a flavone present in Scutellaria baicalensis Georgi, has been demonstrated to possess antitumor activity in a variety of cancer cells in vitro. However, its effects on the growth inhibition and induction of apoptosis in human esophageal carcinoma cells remain unclear. The aims of this study were to determine whether cultured EC-109 esophageal squamous cell carcinoma (ESCC) cells undergo apoptosis when treated with baicalein and to investigate the underlying mechanisms in vitro. Cell growth was measured using MTT and plate colony formation assays. Induction of apoptosis was examined using Hoechst 33258 staining, flow cytometry analysis and a DNA fragmentation assay. The mechanisms underlying the observed growth suppression were examined using western blot analysis. The results demonstrated that treatment of EC-109 cells with baicalein for 48 h markedly decreased the rate of cell viability. Colony formation was almost fully suppressed at 40 μM baicalein. EC-109 cells underwent apoptosis in response to baicalein treatment, demonstrated by an increase in the percentage of cells stainable with Hoechst 33258 and Annexin V-FITC/PI, increased DNA fragmentation and activation of the intrinsic (mitochondrial) pathway for cell death. The latter was characterized by increased expression of the cleaved forms of caspase-9 and -3, and poly (ADP-ribose) polymerase (PARP). Additionally, baicalein was found to downregulate anti-apoptotic components and upregulate apoptotic components of the PI3K/Akt pathway. In conclusion, baicalein induces apoptosis in EC-109 cells through modulation of the PI3K/Akt pathway, thus providing further understanding of the molecular mechanisms of baicalein action in esophageal carcinoma. Therefore, the present study revealed that baicalein significantly inhibits growth and induces apoptosis in EC-109 human ESCC cells in vitro.

Preferential inhibition of hepatocellular carcinoma by the flavonoid Baicalein through blocking MEK-ERK signaling

Baicalein is a purified flavonoid extracted from the roots of Scutellaria baicalensis or Scutellaria radix. Although previous studies have suggested that Baicalein possesses an in vitro anti-hepatocellular carcinoma activity, its in vivo effects and mechanisms of action are still not completely understood. In this study, Baicalein at concentrations of 40-120 µM exhibited significant cytotoxicity to three hepatocellular carcinoma (HCC) cell lines but marginal cytotoxicity to a normal liver cell line in vitro. Compared to a standard chemotherapy drug, 5-fluorouracil (5-FU), Baicalein had greater effect on HCC cells but less toxicity on normal liver cells. Treatment with Baicalein dramatically reduced mitochondrial transmembrane potential, and activated caspase-9 and caspase-3. Blockade of Baicalein-induced apoptosis with a pan-caspase inhibitor partially attenuated Baicalein-induced growth inhibition in HCC. Baicalein treatment significantly inhibited tumor growth of HCC xenografts in mice. Induction of apoptosis was demonstrated in Baicalein-treated xenograft tumors by the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. Furthermore, Baicalein treatment dramatically decreased the levels of phosphorylation of MEK1, ERK1/2 and Bad in vitro and in vivo. Overexpression of human MEK1 partially blocked Baicalein-induced growth inhibition. Consequently, these findings suggest that Baicalein preferentially inhibits HCC tumor growth through inhibition of MEK-ERK signaling and by inducing intrinsic apoptosis.

High-throughput genotoxicity assay identifies antioxidants as inducers of DNA damage response and cell death

Human ATAD5 is a biomarker for identifying genotoxic compounds because ATAD5 protein levels increase posttranscriptionally in response to DNA damage. We screened over 4,000 compounds with a cell-based quantitative high-throughput ATAD5-luciferase assay detecting genotoxic compounds. We identified 22 antioxidants, including resveratrol, genistein, and baicalein, that are currently used or investigated for the treatment of cardiovascular disease, type 2 diabetes, osteopenia, osteoporosis, and chronic hepatitis, as well as for antiaging. Treatment of dividing cells with these compounds induced DNA damage and resulted in cell death. Despite their genotoxic effects, resveratrol, genistein, and baicalein did not cause mutagenesis, which is a major side effect of conventional anticancer drugs. Furthermore, resveratrol and genistein killed multidrug-resistant cancer cells. We therefore propose that resveratrol, genistein, and baicalein are attractive candidates for improved chemotherapeutic agents.

Baicalein inhibits the migration and invasive properties of human hepatoma cells. Toxicol Appl Pharmacol. 2011;255:316-326. [PMID: 21803068 DOI: 10.1016/j.taap.2011.07.008]

Flavonoids have been demonstrated to exert health benefits in humans. We investigated whether the flavonoid baicalein would inhibit the adhesion, migration, invasion, and growth of human hepatoma cell lines, and we also investigated its mechanism of action. The separate effects of baicalein and baicalin on the viability of HA22T/VGH and SK-Hep1 cells were investigated for 24h. To evaluate their invasive properties, cells were incubated on matrigel-coated transwell membranes in the presence or absence of baicalein. We examined the effect of baicalein on the adhesion of cells, on the activation of matrix metalloproteinases (MMPs), protein kinase C (PKC), and p38 mitogen-activated protein kinase (MAPK), and on tumor growth in vivo. We observed that baicalein suppresses hepatoma cell growth by 55%, baicalein-treated cells showed lower levels of migration than untreated cells, and cell invasion was significantly reduced to 28%. Incubation of hepatoma cells with baicalein also significantly inhibited cell adhesion to matrigel, collagen I, and gelatin-coated substrate. Baicalein also decreased the gelatinolytic activities of the matrix metalloproteinases MMP-2, MMP-9, and uPA, decreased p50 and p65 nuclear translocation, and decreased phosphorylated I-kappa-B (IKB)-β. In addition, baicalein reduced the phosphorylation levels of PKCα and p38 proteins, which regulate invasion in poorly differentiated hepatoma cells. Finally, when SK-Hep1 cells were grown as xenografts in nude mice, intraperitoneal (i.p.) injection of baicalein induced a significant dose-dependent decrease in tumor growth. These results demonstrate the anticancer properties of baicalein, which include the inhibition of adhesion, invasion, migration, and proliferation of human hepatoma cells in vivo.

Baicalein potently suppresses angiogenesis induced by vascular endothelial growth factor through the p53/Rb signaling pathway leading to G1/S cell cycle arrest

Vascular endothelial growth factor (VEGF) is a key modulator of angiogenesis. Recent studies have shown that VEGF stimulates endothelial cell growth and modulates the cell cycle by reactivation of G0 cells and by reducing the duration of the G1 phase. This study examined the effect of baicalein, a well-known flavonoid, on VEGF-induced angiogenesis and further investigated the role of cell cycle regulators on the antiangiogenic effects of baicalein. Classic in vivo and in vitro models, including a rat aortic ring model, a wound healing model and a tube formation model were used to evaluate angiogenesis in vivo and in vitro. Baicalein exerted marked inhibition of angiogenesis, significantly inhibited migration of human umbilical vein endothelial cells (HUVECs), suppressed tube formation and reduced new blood vessel growth inducted by VEGF. Baicalein reduced phosphorylation of VEGF receptor 2 and extracellular signal-regulated protein kinase, two major signaling elements modulating endothelial cell proliferation. Baicalein also inhibited colony formation by HUVECs, further confirming the suppression of proliferation. Cell cycle analysis demonstrated that baicalein-treated HUVECs were arrested in the G1/S phase. Baicalein also induced a decline in the expression of G1-related proteins that normally promote transition from the G1 phase to the S phase, including cyclin D, cyclin E, cdk-4, cdk-6 and p-Rb. In contrast, several proteins upstream of cdks and cyclins, including p16, p21, p27 and p53, were up-regulated by baicalein, indicating that baicalein may inhibit angiogenesis, at least in part, by effects on the p53/Rb signaling pathway. Baicalein could exert antitumor effects by inhibiting VEGF-induced angiogenesis and endothelial cell proliferation.

Comparison of spray freeze drying and the solvent evaporation method for preparing solid dispersions of baicalein with Pluronic F68 to improve dissolution and oral bioavailability

The objective of this study was to prepare solid dispersions consisting of baicalein and a carrier with a low glass transition/melting point (Pluronic F68) by spray freeze drying (SFD). We compared these powders to those produced from the conventional solvent evaporation method. In the SFD process, a feeding solution was atomized above the surface of liquid nitrogen following lyophilization, which resulted in instantaneously frozen microparticles. However, solid dispersions prepared by the solvent evaporation method formed a sticky layer on the glass flask with crystalline baicalein separated out from the carrier. The powder samples were characterized by scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), surface area measurement, differential scanning calorimetry, and Fourier transform infrared spectrometry. SEM and PXRD results suggested that the majority of baicalein in the SFD-processed solid dispersion was in the amorphous state, which has a higher specific surface area than pure baicalein. However, the majority of baicalein was recrystallized in the solid dispersion at the same composition prepared by the solvent evaporation method, which showed a similar dissolution rate to the physical mixture. SFD product was physically and chemically stable after being stored at 40 °C with low humidity for 6 months. After enzyme hydrolysis, baicalein in the SFD product displayed a significantly shorter T (max) and higher C (max) than pure baicalein after oral dosing. The relative bioavailability of the SFD product versus pure baicalein determined by comparing the AUC(0-12) was 233%, which demonstrated the significantly improved oral bioavailability of baicalein produced by the SFD technique.

Opposite expression of securin and γ-H2AX regulates baicalein-induced cancer cell death

Securin and γ-H2AX have been shown to regulate cell survival and genomic stability. However, it is still unknown how the expression and regulation of these proteins is altered following treatment with baicalein, a natural flavonoid extracted from the Scutellaria baicalensis root. In the present study, we investigate the possible roles of securin and γ-H2AX in baicalein-induced cancer cell death. Baicalein reduced cell viability in a variety of human cancer cell lines, including bladder, cervical, colon, and lung cancer cells. Interestingly, baicalein treatment (40-80 µM for 24 h) markedly inhibited securin expression, while the levels of γ-H2AX were elevated. Abnormal spindle formation and chromosomal segregation were induced by baicalein. Furthermore, wild type HCT116 cancer cells had a higher incidence of cytotoxicity and apoptosis than securin-null HCT116 cells following treatment with baicalein. In contrast, baicalein increased the levels of γ-H2AX to a similar extent in both cell types. Transfection with H2AX siRNA further increased baicalein-induced cell death. Additionally, blockade of the AKT pathway by treatment with wortmannin or AKT shRNA lowered the levels of γ-H2AX and enhanced cytotoxicity in baicalein-treated cells. Taken together, our findings suggest that the opposing effects of baicalein on securin and γ-H2AX levels may be involved in the regulation of cell viability and genomic stability by this compound.

Baicalein induces cancer cell death and proliferation retardation by the inhibition of CDC2 kinase and survivin associated with opposite role of p38 mitogen-activated protein kinase and AKT

The bioactive flavonoid baicalein has been shown to have in vitro growth-inhibitory activity in human cancer cells, although the mechanism of action is poorly understood. Baicalein (40-80 mumol/L for 24 h) more effectively induced cytotoxicity compared with other flavonoids (baicalin, catechin, genistein, quercetin, and rutin) in bladder cancer cells. Baicalein induced cell proliferation inhibition and apoptosis. The levels of cyclin B1 and phospho-CDC2 (Thr(161)) were reduced, whereas the G(2)-M phases were elevated by baicalein. Treatment of CDC2 kinase or CDC25 phosphatase inhibitors augments the baicalein-induced cytotoxicity. A variety of human bladder cancer cell lines expressed survivin proteins, which were located on the mitotic phases and regulated mitotic progression. Baicalein markedly reduced survivin protein expression. Transfection of a survivin small interfering RNA diminished the level of survivin proteins and increased the baicalein-mediated cell death. Overexpression of survivin enhanced cell proliferation and resisted the baicalein-induced cytotoxicity. Interestingly, baicalein induced the phosphorylation of p38 mitogen-activated protein kinase (MAPK) and AKT. SB203580, a specific p38 MAPK inhibitor, attenuated proliferation inhibition and restored the protein levels of phospho-CDC2 (Thr(161)) and survivin in the baicalein-exposed cells; conversely, blockade of AKT activation enhanced cytotoxicity and the reduction of phospho-CDC2 (Thr(161)) and survivin proteins. As a whole, these findings provide that the opposite role of p38 MAPK and AKT regulates CDC2 kinase and survivin and the inhibition of CDC2-survivin pathway by baicalein contributes to apoptosis and proliferation retardation in cancer cells.

Polyphenols and cancer cell growth

Polyphenols constitute an important group of phytochemicals that gained increased research attention since it was found that they could affect cancer cell growth. Initial evidence came from epidemiologic studies suggesting that a diet that includes regular consumption of fruits and vegetables (rich in polyphenols) significantly reduces the risk of many cancers. In the present work we briefly review the effects of polyphenols on cancer cell fate, leading towards growth, differentiation and apoptosis. Their action can be attributed not only to their ability to act as antioxidants but also to their ability to interact with basic cellular mechanisms. Such interactions include interference with membrane and intracellular receptors, modulation of signaling cascades, interaction with the basic enzymes involved in tumor promotion and metastasis, interaction with oncogenes and oncoproteins, and, finally, direct or indirect interactions with nucleic acids and nucleoproteins. These actions involve almost the whole spectrum of basic cellular machinery--from the cell membrane to signaling cytoplasmic molecules and to the major nuclear components--and provide insights into their beneficial health effects. In addition, the actions justify the scientific interest in this class of compounds, and provide clues about their possible pharmaceutical exploitation in the field of oncology.

Inhibition of 12-lipoxygenase during baicalein-induced human lung nonsmall carcinoma H460 cell apoptosis

Baicalein is known as a 12-lipoxygenase (12-LOX) inhibitor. The 12-LOX is found to be involved in the progression of human cancers and the inhibitor of 12-LOX offers a target for the prevention cancer. We demonstrated the inhibitory effect of baicalein on the gene and protein expression of 12-LOX in H460 human lung nonsmall carcinoma cell line. Treatment of baicalein inhibited the growth of H460 cells in a dose-dependent manner. Following 24h exposure to 50muM baicalein, cell cycle analysis revealed an increase in the cell population in S-phase. During the S-phase arrest, baicalein decreased the protein levels of cdk1 and cyclin B1, which are the regulating proteins of S-phase transition to G2/M-phase, in this study. Furthermore, baicalein induced the most of H460 cell apoptosis after treatment for 48h. H460 cells formed vesicles and apoptotic body, and then floated after treatment with baicalein. Baicalein-induced H460 cell apoptosis was confirmed by DNA condensation and fragmentation. Baicalein-induced apoptosis were also accompanied by decreasing in Bcl-2 and proform of caspase-3 and increasing p53 and Bax protein levels. Pretreatment with a specific caspase-3 inhibitor, Ac-DEVD-CHO, partially reduced baicalein-induced cell death, indicating baicalein induces apoptosis is partially dependent on caspase-3 pathway in H460 cells. These data suggest that baicalein, a 12-LOX inhibitor, inhibits the proliferation of H460 cells via S-phase arrest and induces apoptosis in association with the regulation of molecules in the cell cycle and apoptosis-related proteins.

Baicalein Inhibits Adipocyte Differentiation by Enhancing COX-2 Expression

Baicalein, one of the major flavonoids in Scutellaria baicalensis (Chinese Skullcap), is well known for its effects on cell proliferation, apoptosis, and inflammation. Here we show that baicalein also inhibits the adipogenesis of 3T3-L1 preadipocytes. Baicalein inhibited triglyceride accumulation during adipogenesis and significantly decreased the mRNA expression of fatty acid-binding protein (FABP), a marker of adipogenesis. Microarray analysis revealed that several genes, which are differentially expressed during adipogenesis, were modulated by baicalein treatment in 3T-L1 cells. The expression of FABP, apolipoprotein D, and insulin-like growth factor 2, which was markedly up-regulated during adipogenesis, was down-regulated by baicalein. Cyclooxygenase (COX)-2 mRNA expression, which was decreased during adipogenesis, was up-regulated by baicalein. These COX-2 mRNA expression patterns were mirrored by the expression of COX-2 protein and its enzymatic activity. NS-398, a COX-2 inhibitor, partially abrogated the baicalein-induced inhibition of adipogenensis. Thus, the anti-adipogenic effect of baicalein may be mediated by its ability to enhance the expression of COX-2, which is normally down-regulated during adipogenesis.

Apigenin induced apoptosis through p53-dependent pathway in human cervical carcinoma cells

Apigenin is a widely distributed plant flavonoid and was proposed as an antitumor agent. In this study, we reported for the first time that apigenin inhibited the growth of human cervical carcinoma cells (HeLa) and through apoptotic pathway. The results showed that apigenin significantly decreased the viability of HeLa cells at 37-74 microM and the IC50 value was 35.89 microM. Apigenin-induced apoptosis in HeLa cells was confirmed by DNA fragmentation assay and induction of sub-G1 phase by flow cytometry. Apigenin-treated HeLa cells were arrested at G1 phase, which was associated with a marked increment of the expression of p21/WAF1 protein. The induction of p21/WAF1 appeared to be transcriptionally upregulated and was p53-dependent. In addition, apigenin induced Fas/APO-1 and caspase-3 expression which were also correlated with apoptosis. Apigenin decreased in the protein expression of Bcl-2 protein, which is an anti-apoptotic factor. The conclusion of this study is the apigenin induced p53 expression which caused cell cycle arrest and apoptosis. These findings suggest that apigenin has strong potential for development as an agent for preventing cervical cancer.

Emodin-induced apoptosis through p53-dependent pathway in human hepatoma cells

Most of the commonly used cytotoxic anticancer drugs have been shown to induce apoptosis in susceptible cells. However, the signaling pathway of their apoptotic effects remains undefined. In this study, the cytotoxic effect of emodin on various human hepatoma cell lines was investigated. Results demonstrated that emodin exhibited strongly suppressing effect on HepG2/C3A, PLC/PRF/5, and SK-HEP-1 cells, with the IC(50) value of 42.5, 46.6, and 53.1 microM, respectively. Furthermore, emodin induced apoptosis in HepG2/C3A cells was clearly verified by the appearance of DNA fragmentation and sub-G(1) accumulation. Besides, HepG2/C3A cells were found to be arrested in G(2)/M phase after the cells were treated with 60 microM emodin for 48 h. Moreover, significant increase in the levels of apoptosis-related signals such as p53 (419.3 pg/ml), p21 (437.4 units/ml), Fas (6.6 units/ml), and caspase-3 (35.4 pmol/min) were observed in emodin treated HepG2/C3A cells. Taken together, emodin displays effective inhibitory effects on the growth of various human hepatoma cell lines and stimulates the expression of p53 and p21 that resulted in the cell cycle arrest of HepG2/C3A cells at G(2)/M phase. Results also suggest that emodin-induced apoptosis in HepG2/C3A cells were mediated through the activation of p53, p21, Fas/APO-1, and caspase-3. It implies that emodin could be a useful chemotherapeutical agent for treatment of hepatocellular carcinoma (HCC).

The effects of TNF-α and inhibitors of arachidonic acid metabolism on human colon HT-29 cells depend on differentiation status

The level of differentiation could influence sensitivity of colonic epithelial cells to various stimuli. In our study, the effects of TNF-alpha, inhibitors of arachidonic acid (AA) metabolism (baicalein, BA; indomethacin, INDO; niflumic acid, NA; nordihydroguaiaretic acid, NDGA), and/or their combinations on undifferentiated or sodium butyrate (NaBt)-differentiated human colon adenocarcinoma HT-29 cells were compared. NaBt-treated cells became growth arrested (blocked in G0/G1 phase of the cell cycle), and showed down-regulated Bcl-xL and up-regulated Bak proteins and increased expression of cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LOX). These cells were more perceptive to anti-proliferative and apoptotic effects of TNF-alpha. Both inhibitors of LOX (BA and NDGA) and COX (INDO and NA) in higher concentrations modulated cell cycle changes accompanying NaBt-induced differentiation and induced various level of cell death in undifferentiated and differentiated cells. Most important is our finding that TNF-alpha action on proliferation and cell death can be potentiated by co-treatment of cells with AA metabolism inhibitors, and that these effects were more significant in undifferentiated cells. TNF-alpha and INDO co-treatment was associated with accumulation of cells in G0/G1 cell cycle phase, increased reactive oxygen species production, and elevated caspase-3 activity. These results indicate the role of differentiation status in the sensitivity of HT-29 cells to the anti-proliferative and proapoptotic effects of TNF-alpha, AA metabolism inhibitors, and their combinations, and imply promising possibility for novel anti-cancer strategies.

S29 ribosomal protein induces apoptosis in H520 cells and sensitizes them to chemotherapy

Non-small cell lung cancer (NSCLC) is the most prevalent type of lung cancer especially in India and displays resistance to anticancer treatment. In our earlier study we had isolated a cDNA clone from rat thymocytes induced to undergo apoptosis, which was found to encode S29 ribosomal protein [Biochem. Biophys. Res. Commun. 277 (2000) 476]. In the present study an attempt has been made to find out whether enhanced expression of S29 cDNA can kill NSCLC H520 cells. We found that S29 induced apoptosis and augmented the effect of anticancer drugs. Expressions of several molecular determinants of apoptosis were analyzed in order to understand the mechanism of apoptosis induced by S29. We observed downregulation of the expression of inhibitors of apoptosis proteins (IAPs) Bcl-2, Bcl-X(L), and survivin and upregulation of pro-apoptotic p53 and Bax as assessed by Western blotting. Mitochondrial release of cytochrome c and activation of initiator caspase-8 and -9 and effector caspase-3, followed by cleavage of nuclear substrate poly(ADP-ribose) polymerase, were also observed. Permeability transition as determined by changes in DeltaPsi(m) was not a requirement for cytochrome c release. There was a marginal increase in the release of apoptosis inducing factor (AIF) and reduction of NF-kappaB dependent transcriptional activity. There was non-involvement of calcium and the telomerase activity, a proliferation marker.

Study of apoptosis in human liver cancers

AIM: To investigate the action of apoptosis in occurrence of liver cacinomas in vivo and the biological effect of Solanum lyratum Thumb on BEL-7404 cell line inducing apoptosis in vitro.

METHODS: The apoptosis in the liver carcinoma was detected with terminal deoxynucl neotidyl transferase mediated dUTP nick end labelling (TUNEL); the cancer cells cultured in DMED medium were treated with extract of Solanum lyratum Thumb and observed under microscope, and their DNA was assayed by gel electrophoresis.

RESULTS: In vivo apoptotic cells in the cancer adjacent tissues inceased; in vitro treatment of liver cancers with extract of Solanum lyratum Thumb could induce the cells to manifest a typical apoptotic morphology. Their DNA was fractured and a characteristic ladder pattern could be found using electrophoresis.

CONCLUSION: In vivo the apoptosis of carcinomas was lower; maybe the cells divided quickly and then the cancers occurred. In the cancer adjacent tissues, the apoptosis pricked up, and in vitro Solanum lyratum Thumb could induce the apoptosis of BEL-7404 cells.