Cytotoxicity of Vitex agnus-castus fruit extract and its major component, casticin, correlates with differentiation status in leukemia cell lines

Molecular effects of Mastodynon: realities and prospects for cancer prevention

The article presents updated data concerning the molecular mechanisms of influence of the well-known in clinical practice drug Mastodynon. The paper provides evidence of a significant effect of the compounds containing in its composition on the cell lines of a number of malignant neoplasms: breast cancer, hepatocellular carcinoma, leukemia and others. The data obtained are extremely attractive in the perspective of using the drug as a preventive agent.

Vasorelaxant Effects of the Vitex Agnus-Castus Extract

This study was undertaken to describe and characterize the relaxing effects of the medicinal plant Vitex agnus-castus (VAC) extract on isolated rabbit arterial rings. The VAC extracts (VACE) were extracted with ethanol and tested in aorta rings (3-4 mm) of rabbits suspended in an organ bath (Krebs, 37°C, 95% O₂/5% CO₂) under a resting tension of 1 g to record isometric contractions. After the stabilization period (1-2 hours), contractions were induced by the addition of phenylephrine (0.5 μM) or high KCl (80 mM) and VACE was added on the plateau of the contractions. Experiments were performed to determine the effects and to get insights into the potential mechanism involved in VACE-induced relaxations. The cumulative addition of VACE (0.15–0.75 mg/mL) relaxed, in a concentration-dependent manner, the rabbit aorta rings precontracted either with phenylephrine- or with high KCl thus suggesting calcium channel blocking activities. The VACE effect appeared to be endothelium-dependent. The preincubation with L-NAME (the inhibitor of nitric oxide synthases (NOS)), ODQ (the selective inhibitor of guanylyl cyclase), and indomethacin (the cyclooxygenase inhibitor), downregulated VACE-induced relaxation of aorta rings precontracted with phenylephrine, whereas the bradykinin (stimulator of NOS) and zaprinast (phosphodiesterase inhibitor) further upregulated relaxant effects induced by VACE. These results revealed that the aorta relaxation effect of VACE was mainly endothelium-dependent and mediated by NO/cGMP and prostaglandins synthesis. This vasodilator effect of VACE may be useful to treat cardiovascular disorders, including hypertensive diseases.

Evidence of off-target effects of bosutinib that promote retinoic acid-induced differentiation of non-APL AML cells

In the present study, we determined the effects of the Src family kinase (SFK) inhibitor, Bosutinib, and the engineered loss of the Lyn SFK on all-trans retinoic acid-induced leukemic cell differentiation. Retinoic acid (RA) is an embryonic morphogen and dietary factor that demonstrates chemotherapeutic efficacy in inducing differentiation of a non-APL AML cell model, the HL-60 human myeloblastic (FAB-M2) leukemia cell line, via activation of a novel signalsome containing an ensemble of signaling molecules that drive differentiation. Bosutinib is an inhibitor of SFKs used to treat myeloid leukemias where prominent high expression of SFKs, in particular Lyn, has been observed. Using either Bosutinib or loss of Lyn expression due to shRNA promoted RA-induced phenotypic differentiation, G0 arrest, and respiratory burst (functional differentiation) of HL-60 cells. Signaling events putatively seminal to RA-induced differentiation, the expression of Fgr, Cbl, Slp-76 and Vav, and the phosphorylation of c-Raf (pS259), Vav (p-tyr), and Slp76 (p-tyr) were not inhibited by Bosutinib or loss of Lyn. Nor was RA-induced upregulation of p-tyr phosphorylation of p47phox, a member of the NADPH complex that produces ROS, a putative phosphorylation dependent signaling regulator. Surprisingly, Bosutinib still works in the absence of Lyn to enhance RA-induced differentiation and neither compromised RA-induced expression, nor phosphorylation of signaling molecules that drive differentiation. These findings suggested there is a novel, off-target, Lyn-independent effect of Bosutinib that is of therapeutic significance to differentiation therapy.

Casticin Inhibits In Vivo Growth of Xenograft Tumors of Human Oral Cancer SCC-4 Cells

BACKGROUND/AIM

Casticin, one of the active components of Vitex rotundifolia L., presents biological and pharmacological activities including inhibition of migration, invasion and induction of apoptosis in numerous human cancer cells in vitro. This study aimed to assess the effects of casticin on tumor growth in a human oral cancer SCC-4 cell xenograft mouse model in vivo.

MATERIALS AND METHODS

Twenty-four nude mice were injected subcutaneously with SCC-4 cells and when palpable tumors reached a volume of 100-120 mm³ the mice were randomly divided into three groups. The control (0.1% dimethyl sulfoxide), casticin (0.2 mg/kg), and casticin (0.4 mg/kg) groups were intraperitoneally injected every two days for 18 days. Tumor volume and body weights were measured every two days.

RESULTS

Casticin significantly decreased tumor volume and weight in SCC-4 cell xenograft mice but there was no statistically significant difference between the body weights of control mice and mice treated with 0.2 mg/kg or 0.4 mg/kg casticin. Therefore, the growth of SCC-4 cells in athymic nude mice can be inhibited by casticin in vivo.

CONCLUSION

These findings support further investigations in the potential use of casticin as an oral anti-cancer drug in the future.

Effects of Vitex trifolia L. leaf extracts and phytoconstituents on cytokine production in human U937 macrophages

Background

Dysregulation of pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) form the basis of immune-mediated inflammatory diseases. Vitex trifolia L. is a medicinal plant growing in countries such as China, India, Australia and Singapore. Its dried ripe fruits are documented in Traditional Chinese Medicine to treat ailments like rhinitis and dizziness. Its leaves are used traditionally to treat inflammation-related conditions like rheumatic pain.

Objective

This study aimed to investigate the effects of V. trifolia leaf extracts prepared by different extraction methods (Soxhlet, ultrasonication, and maceration) in various solvents on cytokine production in human U937 macrophages, and identify phytoconstituents from the most active leaf extract.

Methods

Fresh leaves of V. trifolia were extracted using Soxhlet, ultrasonication, and maceration in hexane, dichloromethane, methanol, ethanol or water. Each extract was evaluated for its effects on TNF-α and IL-1β cytokine production by enzyme-linked immunosorbent assay in lipopolysaccharide-stimulated human U937 macrophages. The most active extract was analyzed and further purified by different chemical and spectroscopic techniques.

Results

Amongst 14 different leaf extracts investigated, extracts prepared by ultrasonication in dichloromethane and maceration in ethanol were most active in inhibiting TNF-α and IL-1β production in human U937 macrophages. Further purification led to the isolation of artemetin, casticin, vitexilactone and maslinic acid, and their effects on TNF-α and IL-1β production were evaluated. We report for the first time that artemetin suppressed TNF-α and IL-1β production. Gas chromatography-mass spectrometry analyses revealed the presence of eight other compounds. To the best of our knowledge, this is the first report of butylated hydroxytoluene, 2,4-di-tert-butylphenol, campesterol and maslinic acid in V. trifolia leaf extracts.

Conclusions

In conclusion, leaf extracts of V. trifolia obtained using different solvents and extraction methods were successfully investigated for their effects on cytokine production in human U937 macrophages. The findings provide scientific evidence for the traditional use of V. trifolia leaves (a sustainable resource) and highlight the importance of conservation of medicinal plants as resources for drug discovery. Our results together with others suggest further investigation on V. trifolia and constituents to develop novel treatment strategies in immune-mediated inflammatory conditions is warranted.

Correlation between cytotoxicity in cancer cells and free radical-scavenging activity: In vitro evaluation of 57 medicinal and edible plant extracts

Cancer is a complex interaction among multiple signaling pathways involving a variety of target molecules. Cancer causes morbidity and mortality in millions of people worldwide, and due to its prevalence, the discovery of novel anticancer drugs is urgently required. Nature is considered an important source of the discovery of anticancer treatments, and many of the cytotoxic medicines in clinics today are derived from plants and other natural sources. Reactive oxygen species (ROS) induce a variety of human cancers, and antioxidants or scavengers are used to counteract them. The current study reports on the screening of extracts from 57 plants that are used in the galilee district as a food and/or for traditional medicine. Investigating the free radical scavenging capacity and these plants, and their cytotoxicity, may prove helpful to high-throughput screening projects that use antioxidants and cytotoxic natural products. The current study assessed the correlation between free radical scavenging and cytotoxicity. Correlational analysis is important for increasing the efficiency of the screening process. In the present study, free radical scavenging was assessed using a DPPH assay, while cytotoxicity was measured using a XTT assay. A total of 9 extracts were indicated to exhibit EC₅₀ values <250 µg/ml, and 4 others exhibited a high antioxidant content, with EC₅₀ values, for free radical scavenging, of <0.5 µg/ml. An in-depth analysis of the results revealed that the extracts of plants that exhibit an EC₅₀ of free radical scavenging ≤10 µg/ml show a degree of enrichment toward increased cytotoxicity. It is recommended that future studies test the validity of the conclusions of the current study on other cancer cell-lines, and isolate and identify the bioactive agents that are found in the most cytotoxic extracts of plants.

Casticin inhibits human prostate cancer DU 145 cell migration and invasion via Ras/Akt/NF-κB signaling pathways

Casticin, a polymethoxyflavone derived from natural plants, has biological activities including induction of cell apoptosis. In this study, we showed the beneficial effects of casticin on the inhibition of prostate cancer cell metastasis. Casticin reduced total viable cell number, thus, we selected low doses of casticin for following experiments. Casticin decreased cell mobility, suppressed cell migration and invasion, and reduced cell gelatinolytic activities of MMP-2/-9. Furthermore, casticin inhibited the protein levels of AKT, GSK3 αβ, Snail, and MMPs (MMP-2, -9, -13, and -7) at 24 and 48 hr treatment. Casticin diminished the expressions of NF-κB p65, GRB2, SOS-1, MEK, p-ERK1/2, and p-JNK1/2 at 48 hr treatment only. However, casticin reduced the level of E-cadherin at 24 hr treatment but elevated at 48 hr. The novel findings suggest that casticin may represent a new and promising therapeutic agent for the metastatic prostate cancer. PRACTICAL APPLICATIONS: Casticin derived from natural plants had been used for Chinese medicine in Chinese population for thousands of years. In the present study, casticin attenuated metastatic effects, including decreasing viable cell number, inhibiting the migration, invasion, and adhesion, and reducing matrix metalloproteinases activity on human prostate DU 145 cancer cells. In addition, the results also provided possible pathways involved in casticin anti-metastasis mechanism. We conclude that casticin may be an aptitude anticancer agent or adjuvant for the metastatic prostate cancer in the future.

Casticin-Induced Inhibition of Cell Growth and Survival Are Mediated through the Dual Modulation of Akt/mTOR Signaling Cascade

The Akt/mTOR signaling cascade is a critical pathway involved in various physiological and pathological conditions, including regulation of cell proliferation, survival, invasion, and angiogenesis. In the present study, we investigated the anti-neoplastic effects of casticin (CTC), identified from the plant Vitex rotundifolia L., alone and/or in combination with BEZ-235, a dual Akt/mTOR inhibitor in human tumor cells. We found that CTC exerted a significant dose-dependent cytotoxicity and reduced cell proliferation in a variety of human tumor cells. Also, CTC effectively blocked the phosphorylation levels of Akt (Ser473) and mTOR (Ser2448) proteins as well as induced substantial apoptosis. Additionally treatment with CTC and BEZ-235 in conjunction resulted in a greater apoptotic effect than caused by either agent alone thus implicating the anti-neoplastic effects of this novel combination. Overall, the findings suggest that CTC can interfere with Akt/mTOR signaling cascade involved in tumorigenesis and can be used together with pharmacological agents targeting Akt/mTOR pathway.

Casticin inhibits growth and enhances ionizing radiation-induced apoptosis through the suppression of STAT3 signaling cascade

Casticin (CTC), one of the major components of Vitex rotundifolia L., has been reported to exert significant beneficial pharmacological activities and can function as an antiprolactin, anticancer, anti-inflammatory, neuroprotective, analgesic, and immunomodulatory agent. This study aimed at investigating whether the proapoptotic effects of CTC may be mediated through the abrogation of signal transducers and activators of transcription-3 (STAT3) signaling pathway in a variety of human tumor cells. We found that CTC significantly decreased cell viability in a concentration-dependent manner and suppressed cell proliferation in 786-O, YD-8, and HN-9 cells. CTC also induced programmed cell death that was found to be mediated via caspase-3 activation and induction of poly(ADP-ribose) polymerase cleavage. Interestingly, CTC repressed both constitutive and interleukin-6-induced STAT3 activation in 786-O and YD-8 cells but only affected constitutive STAT3 phosphorylation in HN-9 cells. Moreover, CTC could potentiate ionizing radiation-induced apoptotic effects leading to the downregulation of STAT3 activation and thus may be used in combination with radiation against diverse malignancies.

Casticin from Vitex species: a short review on its anticancer and anti-inflammatory properties

This short review provides an update of the anticancer and anti-inflammatory properties of casticin from Vitex species. Casticin is a polymethylflavone with three rings, an orthocatechol moiety, a double bond, two hydroxyl groups and four methoxyl groups. Casticin has been isolated from various tissues of plants in the Vitex genus: fruits and leaves of V. trifolia, aerial parts and seeds of V. agnus-castus and leaves of V. negundo. Studies have reported the antiproliferative and apoptotic activities of casticin from Vitex species. The compound is effective against many cancer cell lines via different molecular mechanisms. Studies have also affirmed the anti-inflammatory properties of casticin, with several molecular mechanisms identified. Other pharmacological properties include anti-asthmatic, tracheospasmolytic, analgesic, antihyperprolactinemia, immunomodulatory, opioidergic, oestrogenic, anti-angiogenic, antiglioma, lung injury protection, rheumatoid arthritis amelioration and liver fibrosis attenuation activities. Clinical trials and commercial use of the casticin-rich fruit extract of V. agnus-castus among women with premenstrual syndrome were briefly discussed.

Rosehip inhibits xanthine oxidase activity and reduces serum urate levels in a mouse model of hyperuricemia

Rosehip, the fruit of Rosa canina L., has traditionally been used to treat urate metabolism disorders; however, its effects on such disorders have not been characterized in detail. Therefore, the present study investigated the effects of hot water, ethanol and ethyl acetate extracts of rosehip on xanthine oxidase (XO) activity in vitro. In addition, the serum urate lowering effects of the rosehip hot water extract in a mouse model of hyperuricemia (male ddY mice, which were intraperitoneally injected with potassium oxonate) were investigated. Furthermore, the influence of rosehip hot water extract on CYP3A4 activity, which is the most important drug-metabolizing enzyme from a herb-drug interaction perspective, was investigated. Rosehip extracts of hot water, ethanol and ethyl acetate inhibited XO activity [half maximal inhibitory concentration (IC50) values: 259.6±50.6, 242.5±46.2 and 1,462.8±544.2 µg/ml, respectively]. Furthermore, the administration of 1X rosehip hot water extract significantly reduced the levels of serum urate at 8 h, which was similar when compared with the administration of 1 mg/kg allopurinol. Rosehip hot water extract only marginally affected CYP3A4 activity (IC50 value, >1 mg/ml). These findings indicate that rosehip hot water extract may present as a functional food for individuals with a high urate level, and as a therapeutic reagent for hyperuricemic patients.

Casticin inhibits the activity of transcription factor Sp1 and the methylation of RECK in MGC803 gastric cancer cells

The present study investigated the effect of casticin on reversion-inducing-cysteine-rich protein with kazal motifs (RECK) gene expression and intracellular methylation levels in MGC803 gastric cancer cells. Cells were treated with 1, 10 and 30 µmol/l casticin. Western blotting and reverse transcription-quantitative polymerase chain reaction assays were performed to determine the protein expression and mRNA levels of RECK and DNA methyltransferase 1 (DNMT1), respectively. High-performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry was used to detect RECK methylation. In addition, MGC803 cell proliferation was measured by an MTT assay and the DNA-binding activity of transcription factor Sp1 was determined using an enzyme-linked immunosorbent assay. The results demonstrated that treatment with 1, 10 and 30 µmol/l casticin significantly increased RECK protein expression and mRNA levels. In addition, casticin (30 µmol/l) decreased RECK promoter methylation levels by 31%, global DNA methylation levels by 39% and nuclear methylation activity by 71.6%. Furthermore, casticin downregulated the mRNA levels and protein expression of DNMT1. The MTT assay demonstrated that MGC803 cell proliferation was inhibited by casticin treatment and DNA binding assays indicated that casticin reduced the DNA-binding activity of Sp1. The present study therefore indicated that casticin inhibits the proliferation of gastric cancer MGC803 cells by upregulating RECK gene expression and reducing intracellular methylation levels.

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

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

The LC/ESI-MSMS Profiles and Biological Potentials of Vitex agnus castus Extracts

The chemical profile, cytotoxic and apoptotic effect, and antioxidant activity were determined of ethanolic extracts of Vitex agnus-castus L. (chaste tree). Ripened fruits and fruitless aerial parts were extracted with ethanol, and the chemical characterization of the extracts was determined by LC/ESI-MS-MS. Twelve compounds were tentatively identified in the extracts. The dose-dependent cytotoxic effects of the extracts were tested on C6, A549 and MCF-7 cells by using MTT assay; inhibition of DNA synthesis, and apoptotic and caspase-3 activation effects of the extracts were determined. The potential antioxidant activities of the extracts were evaluated by in vitro methods such as DPPH and ABTS scavenging activity, reducing power and β-carotene bleaching assays. The fruit extract showed noticeable cytotoxic activity against MCF-7 cells with an IC50 value of 88 μg/mL. Both extracts showed similar DPPH scavenging activity comparably with that of the standard.

Effects of active bufadienolide compounds on human cancer cells and CD4+CD25+Foxp3+ regulatory T cells in mitogen-activated human peripheral blood mononuclear cells

The growth inhibitory effects of bufadienolide compounds were investigated in two intractable cancer cells, a human glioblastoma cell line U-87 and a pancreatic cancer cell line SW1990. Among four bufadienolide compounds, a dose-dependent cytotoxicity was observed in these cancer cells after treatment with gamabufotalin and arenobufagin. The IC50 values of the two compounds were 3-5 times higher in normal peripheral blood mononuclear cells (PBMCs) than these values for both cancer cell lines. However, similar phenomena were not observed for two other bufadienolide compounds, telocinobufagin and bufalin. These results thus suggest that gamabufotalin and arenobufagin possess selective cytotoxic activity against tumor cells rather than normal cells. Moreover, a clear dose-dependent lactate dehydrogenase (LDH) release, a well-known hallmark of necrosis, was observed in both cancer cells treated with gamabufotalin, suggesting that gamabufotalin-mediated cell death is predominantly associated with a necrosis-like phenotype. Of most importance, treatment with as little as 8 ng/ml of gamabufotalin, even an almost non-toxic concentration to PBMCs, efficiently downregulated the percentages of CD4+CD25+Foxp3+ regulator T (Treg) cells in mitogen-activated PBMCs. Given that Treg cells play a critical role in tumor immunotolerance by suppressing antitumor immunity, these results suggest that gamabufotalin may serve as a promising candidate, as an adjuvant therapeutic agent by manipulating Treg cells to enhance the efficacy of conventional anticancer drugs and lessen their side-effects. These findings provide insights into the clinical application of gamabufotalin for cancer patients with glioblastoma/pancreatic cancer based on its cytocidal effect against tumor cells as well as its depletion of Treg cells.

Lyn, a tyrosine kinase closely linked to the differentiation status of primary acute myeloid leukemia blasts, associates with negative regulation of all-trans retinoic acid (ATRA) and dihydroxyvitamin D3 (VD3)-induced HL-60 cells differentiation

Background

Lyn, an import member of Src family kinases (SFKs), is supposed to be implicated in acute myeloid leukemia (AML) pathogenesis and development by participation in AML differentiation, yet the details still remain incompletely understood. The expression status of Lyn and its correlation with multiple clinical parameters including cell differentiation degree, different cytogenetic risk classification, and the activity of myeloperoxidase (MPO) were thus investigated. To address the mechanisms underlying the involvement of Lyn in differentiation induction, the effects of dasatinib, an inhibitor for SFKs including Lyn, on the alterations of all-trans retinoic acid (ATRA)- or dihydroxyvitamin D3 (VD3)-induced differentiation, and c-Myc protein expression were investigated.

Methods

Primary AML blasts were obtained from 31 newly diagnosed AML patients with different French-American-British (FAB) subtypes. The expression of phosphorylated and total Lyn, c-Myc, and CD11b, CD11c and CD15 was analyzed by flow cytometry. The activation of Akt and Erk known to be involved in the regulation of c-Myc expression was investigated using western blotting.

Results

Significant higher expression levels of total Lyn were observed in AML patients with favorable cytogenetics, higher MPO activity and FAB M2 subtype. A clear positive correlation between the expression levels of Lyn and differentiation status of primary AML blasts was observed. Dasatinib inhibited the expression of phosphorylated Lyn, and further enhanced the differentiation-inducing activity of ATRA and VD3 in HL-60 cells. Augmented downregulation of c-Myc protein expression was observed in the combination treatment with ATRA, VD3 and dasatinib compared to treatment with each reagent alone in HL-60 cells. The suppression of the activation of Akt and Erk was also observed concomitantly.

Conclusions

The expression level of total Lyn is closely linked to the differentiation status of AML blasts. The enhancement of differentiation-inducing activity of ATRA/VD3 by dasatinib suggested that Lyn was associated in the negative regulation of ATRA/VD3-induced HL-60 cells differentiation. The enhancement probably was attributed to the downregulation of c-Myc implicated with the suppression of the activation of Akt and Erk. These results provide novel insights into a possible combinational therapeutic approach by targeting Lyn for AML patients, and offer new possibilities for the combination therapy with VD3 and dasatinib.

Involvement of histone H3 phosphorylation via the activation of p38 MAPK pathway and intracellular redox status in cytotoxicity of HL-60 cells induced by Vitex agnus-castus fruit extract

We have demonstrated that an extract from the ripe fruit of Vitex angus-castus (Vitex), might be a promising anticancer candidate. In order to further provide a molecular rationale for clinical development in anticancer therapy, a detailed mechanism underlying the efficacy of Vitex against HL-60 cells was investigated. Vitex induced a dose- and time-dependent decrease in cell viability associated with induction of apoptosis and G(2)/M cell cycle arrest, both of which were suppressed by the addition of SB203580, an inhibitor for p38 MAPK. Furthermore, SB203580 significantly suppressed Vitex-induced phosphorylation of histone H3, a downstream molecule of p38 MAPK known to be involved in apoptosis induction in tumor cells. Notably, Vitex induced upregulation of intracellular ATP, known to bind its binding pocket inside activated p38 MAPK and to be required for the activation of p38 MAPK pathway. These results, thus, suggest that upregulation of intracellular ATP and phosphorylation of histone H3 are closely associated with the activation of p38 MAPK pathway, consequently contributing to Vitex-mediated cytotoxicity. Intriguingly, a significant decrease of intracellular ROS levels and downregulation of expression level of gp91(phox), an important component of NADPH oxidase, were observed in Vitex-treated cells. A greater decline in ROS levels along with enhanced apoptosis was observed after treatment with Vitex in combination with SnPP, an inhibitor specific for HO-1. Since NADPH oxidase and HO-1 are closely correlated to redox status associated with intracellular ROS levels, the two enzymes are suggested to be implicated in Vitex-mediated cytotoxicity in HL-60 cells by regulating ROS generation. We also suggest that activation of the p38 MAPK pathway may be dependent on the alterations of intracellular ATP levels, rather than that of intracellular ROS levels. These results may have important implications for appropriate clinical uses of Vitex and provide novel insights into the interaction between Vitex and other conventional drugs capable of affecting intracellular redox status.