Hyperforin inhibits MMP-9 secretion by B-CLL cells and microtubule formation by endothelial cells

Targeting extracellular matrix through phytochemicals: a promising approach of multi-step actions on the treatment and prevention of cancer

Extracellular matrix (ECM) plays a pivotal and dynamic role in the construction of tumor microenvironment (TME), becoming the focus in cancer research and treatment. Multiple cell signaling in ECM remodeling contribute to uncontrolled proliferation, metastasis, immune evasion and drug resistance of cancer. Targeting trilogy of ECM remodeling could be a new strategy during the early-, middle-, advanced-stages of cancer and overcoming drug resistance. Currently nearly 60% of the alternative anticancer drugs are derived from natural products or active ingredients or structural analogs isolated from plants. According to the characteristics of ECM, this manuscript proposes three phases of whole-process management of cancer, including prevention of cancer development in the early stage of cancer (Phase I); prevent the metastasis of tumor in the middle stage of cancer (Phase II); provide a novel method in the use of immunotherapy for advanced cancer (Phase III), and present novel insights on the contribution of natural products use as innovative strategies to exert anticancer effects by targeting components in ECM. Herein, we focus on trilogy of ECM remodeling and the interaction among ECM, cancer-associated fibroblasts (CAFs) and tumor-associated macrophages (TAMs), and sort out the intervention effects of natural products on the ECM and related targets in the tumor progression, provide a reference for the development of new drugs against tumor metastasis and recurrence.

Hyperforin: A natural lead compound with multiple pharmacological activities

Hypericum perforatum L. (Clusiaceae), commonly known as St. John's wort, has a rich historical background as one of the oldest and most widely studied herbal medicines. Hyperforin is the main antidepressant active ingredient of St. John's wort. In recent years, hyperforin has attached increasing attention due to its multiple pharmacological activities. In this review, the information on hyperforin was systematically summarized. Hyperforin is considered to be a lead compound with diverse pharmacological activities including anti-depression, anti-tumor, anti-dementia, anti-diabetes and others. It can be obtained by extraction and synthesis. Further pharmacological studies and more precise detection methods will help develop a value for hyperforin. In addition, structural modification and pharmaceutical preparation technology will be beneficial to promoting the research progress of hyperforin based innovative drugs. Although these works are full of known and unknown challenges, researchers are still expected to make hyperforin play a greater value.

Hyperforin Elicits Cytostatic/Cytotoxic Activity in Human Melanoma Cell Lines, Inhibiting Pro-Survival NF-κB, STAT3, AP1 Transcription Factors and the Expression of Functional Proteins Involved in Mitochondrial and Cytosolic Metabolism

Hyperforin (HPF), the main component responsible for the antidepressant action of Hypericum perforatum, displays additional beneficial properties including anti-inflammatory, antimicrobic, and antitumor activities. Among its antitumor effects, HPF activity on melanoma is poorly documented. Melanoma, especially BRAF-mutated melanoma, is still a high-mortality tumor type and the currently available therapies do not provide solutions. We investigated HPF's antimelanoma effectiveness in A375, FO1 and SK-Mel-28 human BRAF-mutated cell lines. Cell viability assays documented that all melanoma cells were affected by low HPF concentrations (EC50% 2-4 µM) in a time-dependent manner. A Br-deoxy-uridine incorporation assay attested a significant reduction of cell proliferation accompanied by decreased expression of cyclin D1 and A2, CDK4 and of the Rb protein phosphorylation, as assessed by immunoblots. In addition, the expression of P21/waf1 and the activated form of P53 were increased in A375 and SK-Mel-28 cells. Furthermore, HPF exerts cytotoxic effects. Apoptosis is induced 24 h after HPF administration, documented by an increase of cleaved-PARP1 and a decrease of both Bcl2 and Bcl-xL expression levels. Autophagy is induced, attested by an augmented LC3B expression and augmentation of the activated form of AMPK. Moreover, HPF lowers GPX4 enzyme expression, suggesting ferroptosis induction. HPF has been reported to activate the TRPC6 Ca⁺⁺ channel and/or Ca⁺⁺ and Zn⁺⁺ release from mitochondria stores, increasing cytosolic Ca⁺⁺ and Zn⁺⁺ concentrations. Our data highlighted that HPF affects many cell-signaling pathways, including signaling induced by Ca⁺⁺, such as FRA1, pcJun and pCREB, the expression or activity of which are increased shortly after treatment. However, the blockage of the TRPC6 Ca⁺⁺ channel or the use of Ca⁺⁺ and Zn⁺⁺ chelators do not hinder HPF cytostatic/cytotoxic activity, suggesting that damages induced in melanoma cells may pass through other pathways. Remarkably, 24 h after HPF treatment, the expression of activated forms of the transcription factors NF-κB P65 subunit and STAT3 are significantly lowered. Several cytosolic (PGM2, LDHA and pPKM2) and mitochondrial (UQCRC1, COX4 and ATP5B) enzymes are downregulated by HPF treatment, suggesting a generalized reduction of vital functions in melanoma cells. In line with these results is the recognized ability of HPF to affect mitochondrial membrane potential by acting as a protonophore. Finally, HPF can hinder both melanoma cell migration and colony formation in soft agar. In conclusion, we provide evidence of the pleiotropic antitumor effects induced by HPF in melanoma cells.

Anti-Tumor Activity of Hypericum perforatum L. and Hyperforin through Modulation of Inflammatory Signaling, ROS Generation and Proton Dynamics

In this paper we review the mechanisms of the antitumor effects of Hypericum perforatum L. (St. John's wort, SJW) and its main active component hyperforin (HPF). SJW extract is commonly employed as antidepressant due to its ability to inhibit monoamine neurotransmitters re-uptake. Moreover, further biological properties make this vegetal extract very suitable for both prevention and treatment of several diseases, including cancer. Regular use of SJW reduces colorectal cancer risk in humans and prevents genotoxic effects of carcinogens in animal models. In established cancer, SJW and HPF can still exert therapeutic effects by their ability to downregulate inflammatory mediators and inhibit pro-survival kinases, angiogenic factors and extracellular matrix proteases, thereby counteracting tumor growth and spread. Remarkably, the mechanisms of action of SJW and HPF include their ability to decrease ROS production and restore pH imbalance in tumor cells. The SJW component HPF, due to its high lipophilicity and mild acidity, accumulates in membranes and acts as a protonophore that hinders inner mitochondrial membrane hyperpolarization, inhibiting mitochondrial ROS generation and consequently tumor cell proliferation. At the plasma membrane level, HPF prevents cytosol alkalization and extracellular acidification by allowing protons to re-enter the cells. These effects can revert or at least attenuate cancer cell phenotype, contributing to hamper proliferation, neo-angiogenesis and metastatic dissemination. Furthermore, several studies report that in tumor cells SJW and HPF, mainly at high concentrations, induce the mitochondrial apoptosis pathway, likely by collapsing the mitochondrial membrane potential. Based on these mechanisms, we highlight the SJW/HPF remarkable potentiality in cancer prevention and treatment.

Antiproliferative Effects of St. John's Wort, Its Derivatives, and Other Hypericum Species in Hematologic Malignancies

Hypericum is a widely present plant, and extracts of its leaves, flowers, and aerial elements have been employed for many years as therapeutic cures for depression, skin wounds, and respiratory and inflammatory disorders. Hypericum also displays an ample variety of other biological actions, such as hypotensive, analgesic, anti-infective, anti-oxidant, and spasmolytic abilities. However, recent investigations highlighted that this species could be advantageous for the cure of other pathological situations, such as trigeminal neuralgia, as well as in the treatment of cancer. This review focuses on the in vitro and in vivo antitumor effects of St. John’s Wort (Hypericum perforatum), its derivatives, and other Hypericum species in hematologic malignancies. Hypericum induces apoptosis in both myeloid and lymphoid cells. Other Hypericum targets include matrix metalloproteinase-2, vascular endothelial growth factor, and matrix metalloproteinase-9, which are mediators of cell migration and angiogenesis. Hypericum also downregulates the expression of proteins that are involved in the resistance of leukemia cells to chemotherapeutic agents. Finally, Hypericum and its derivatives appear to have photodynamic effects and are candidates for applications in tumor photodynamic therapy. Although the in vitro studies appear promising, controlled in vivo studies are necessary before we can hypothesize the introduction of Hypericum and its derivatives into clinical practice for the treatment of hematologic malignancies.

Bicyclic polyprenylated acylphloroglucinols and their derivatives: structural modification, structure-activity relationship, biological activity and mechanism of action

Bicyclic polyprenylated acylphloroglucinols (BPAPs), the principal bioactive benzophenone products isolated from plants of genera Garcinia and Hypericum, have attracted noticeable attention from the synthetic and biological communities due to their fascinating chemical structures and promising biological activities. However, the potential drug interaction, undesired physiochemical properties and toxicity have limited their potential use and development. In the last decade, pharmaceutical research on the structural modifications, structure-activity relationships (SARs) and mechanisms of action of BPAPs has been greatly developed to overcome the challenges. A comprehensive review of these scientific literature is extremely needed to give an overview of the rapidly emerging area and facilitate research related to BPAPs. This review, containing over 226 references, covers the progress made in the chemical synthesis-based structure modifications, SARs and the mechanism of action of BPAPs in vivo and vitro. The most relevant articles will focus on the discovery of lead compounds via synthetic modifications and the important BPAPs for which the direct targets have been deciphered. From this review, several key points of the SARs and mode of actions of this novel class of compounds have been summarized. The perspective and future direction of the research on BPAPs are concluded. This review would be helpful to get a better grasp of medicinal research of BPAPs and become a compelling guide for chemists dedicated to the synthesis of these compounds.

Bioactive Compounds from Seaweed with Anti-Leukemic Activity: A Mini-Review on Carotenoids and Phlorotannins

Chronic Myeloid Leukemia (CML) represents 15-20% of all new cases of leukemia and is characterized by an uncontrolled proliferation of abnormal myeloid cells. Currently, the first-line of treatment involves Tyrosine Kinase Inhibitors (TKIs), which specifically inhibits the activity of the fusion protein BCR-ABL. However, resistance, mainly due to mutations, can occur. In the attempt to find more effective and less toxic therapies, several approaches are taken into consideration such as research of new anti-leukemic drugs and "combination chemotherapy" where different drugs that act by different mechanisms are used. Here, we reviewed the molecular mechanisms of CML, the main mechanisms of drug resistance and current strategies to enhance the therapeutic effect of TKIs in CML. Despite major advances in CML treatment, new, more potent anticancer drugs and with fewer side effects are needed. Marine organisms, and particularly seaweed, have a high diversity of bioactive compounds with some of them having anticancer activity in several in vitro and in vivo models. The state-of-art suggests that their use during cancer treatment may improve the outcome. We reviewed here the yet few data supporting anti-leukemic activity of some carotenoids and phlorotannins in some leukemia models. Also, strategies to overcome drug resistance are discussed, particularly the combination of conventional drugs with natural compounds.

Novel Insights into the Effect of Hyperforin and Photodynamic Therapy with Hypericin on Chosen Angiogenic Factors in Colorectal Micro-Tumors Created on Chorioallantoic Membrane

Photodynamic therapy with hypericin (HY-PDT) and hyperforin (HP) could be treatment modalities for colorectal cancer (CRC), but evidence of their effect on angiogenic factors in CRC is missing. Convenient experimental model utilization is essential for angiogenesis research. Therefore, not only 2D cell models, but also 3D cell models and micro-tumors were used and compared. The micro-tumor extent and interconnection with the chorioallantoic membrane (CAM) was determined by histological analyses. The presence of proliferating cells and HY penetration into the tumor mass were detected by fluorescence microscopy. The metabolic activity status was assessed by an colorimetric assay for assessing cell metabolic activity (MTT assay) and HY accumulation was determined by flow cytometry. Pro-angiogenic factor expression was determined by Western blot and quantitative real-time polymerase chain reaction (RT-qPCR). We confirmed the cytotoxic effect of HY-PDT and HP and showed that their effect is influenced by structural characteristics of the experimental model. We have pioneered a method for analyzing the effect of HP and cellular targeted HY-PDT on pro-angiogenic factor expression in CRC micro-tumors. Despite the inhibitory effect of HY-PDT and HP on CRC, the increased expression of some pro-angiogenic factors was observed. We also showed that CRC experimental micro-tumors created on quail CAM could be utilized for analyses of gene and protein expression.

Topically applied hypericin exhibits skin penetrability on nude mice

Hypericin, a powerful natural photosensitizer in photodynamic therapy (PDT), is suitable for treating skin diseases involving excess capillary proliferation. In the present study, we aimed to evaluate the skin penetrability of topically applied hypericin, expecting a reduced risk of prolonged skin photosensitivity, which often occurs after systemic administration. Firstly, the Franz diffusion cell assays were performed to evaluate the penetration effects of different enhancers, including menthol, propylene glycol, camphanone, azone, and carbamide. In view of above evaluation results, we selected menthol as the enhancer in the subsequent in vivo studies. The setting groups were as follows: the blank control group, the light-exposure control group, the gel-base control group, the hypericin gel group, and a hypericin gel-containing menthol group. Except for the blank control, all other animals were irradiated by a LED light. Then, fluorescence microscopy was performed to examine the distribution of hypericin in the skin of nude mouse. Macroscopic and microscopic analyses were also carried out to detect pathological changes in the skin after topical hypericin-PDT treatment. Immunohistochemistry was used to determine the expression change of PECAM-1. As shown in the results, menthol facilitated hypericin penetrate the skin of nude mice most. The results of in vivo assays revealed that hypericin penetrated nude mouse skin, spread to the dermis, and resulted in obvious photosensitivity reaction on the dermal capillaries. Moreover, skin injured by the photosensitive reaction induced by hypericin-PDT treatment was replaced by normal skin within 7 days. We concluded that topical applied hypericin could penetrate nude mouse skin well and has a great potential in PDT treatment of skin diseases.

Evaluation of the cytotoxic activity of Hypericum spp. on human glioblastoma A1235 and breast cancer MDA MB-231 cells

Cytotoxic activity of 16 Hypericum ethanolic extracts was evaluated by MTT assay on two human cancer cell lines: glioblastoma A1235 and breast cancer MDA MB-231. Morphology and the type of induced cell death were determined using light and fluorescence microscopy. The majority of Hypericum extracts had no significant cytotoxic effect on MDA MB-231 cells. Eight extracts exhibited mild cytotoxic effect on A1235 cells after 24 h incubation, ranging from 8.0% (H. patulum) to 21.7% (H. oblongifolium). After 72 h of treatment, the strongest inhibition of A1235 viability was observed for extracts of H. androsaemum (26.4-43.9%), H. balearicum (25.8-36.3%), H. delphicum (14.8-27.4%) and H. densiflorum (11.2-24.1%). Micro-scopic examination of cells showed apoptosis as the dominant type of cell death. Due to observed high viability of treated cells, we propose that cytotoxic effects of Hypericum extracts could be related to alternations/interruptions in the cell cycle.

Hypericin-photodynamic therapy induces human umbilical vein endothelial cell apoptosis

The conventional photosensitizers used in photodynamic therapy (PDT), such as haematoporphyrin (HP), have not yet reached satisfactory therapeutic effects on port-wine stains (PWSs), due largely to the long-term dark toxicity. Previously we have showed that hypericin exhibited potent photocytotoxic effects on Roman chicken cockscomb model of PWSs. However, the molecular mechanism of hypericin-mediated photocytotoxicity remains unclear. In this study, we employed human umbilical vein endothelial cells (HUVECs) to investigate the hypericin-photolytic mechanism. Our study showed that hypericin-PDT induced reactive oxygen species (ROS), resulting in cell killings and an activation of the inflammatory response. Importantly, we have also discovered that photoactivated hypericin induced apoptosis by activating the mitochondrial caspase pathway and inhibiting the activation of the vascular endothelial growth factor-A (VEGF-A)-mediated PI3K/Akt pathway. Notably, we found that hypericin exhibited a more potent photocytotoxic effect than HP, and largely addressed the inconvenience issue associated with the use of HP. Thereby, hypericin may be a better alternative to HP in treating PWSs.

Hypericin damages the ectatic capillaries in a Roman cockscomb model and inhibits the growth of human endothelial cells more potently than hematoporphyrin does through induction of apoptosis

Hypericin (HY) is a promising photosensitizer (PS) for use in photodynamic therapy (PDT). Port-wine stains (PWSs) are congenital superficial dermal capillary malformations. In this study, we evaluated the photocytotoxic effects of HY for PDT in human vascular endothelial cells and a chicken cockscomb model. HY significantly inhibited the growth of human umbilical vein endothelial cells (HUVECs), as determined by colorimetric assays and morphological observation, and flow cytometry assays indicated induction of apoptosis and collapse of the mitochondrial membrane potential. In addition, HY more effectively inhibited growth of and induced apoptosis in HUVECs compared with hematoporphyrin (HP). Further experiments performed in a Roman chicken cockscomb model also showed a clear photocytotoxic effect on the cockscomb dermal capillary upon intravenous injection of HY. This effect may be due to the role of HY in the induction of apoptosis. Transmission electron microscopical analysis showed mitochondrial morphological changes such as incomplete ridges and swelling, and immunohistochemical assays showed an increase in the release of cytochrome c. In conclusion, HY exhibited a greater photocytotoxic activity than did HP toward the growth of endothelial cells and may thus represent a potent PS for PWS PDT.

Critical signal transduction pathways in CLL

Receptor tyrosine kinases (RTKs) are cell-surface transmembrane receptors that contain regulated kinase activity within their cytoplasmic domain and play a critical role in signal transduction in both normal and malignant cells. Besides B cell receptor (BCR) signaling in chronic lymphocytic leukemia (CLL), multiple RTKs have been reported to be constitutively active in CLL B cells, resulting in enhanced survival and resistance to apoptosis of the leukemic cells induced by chemotherapeutic agents. In addition to increased plasma levels of various types of cytokines/growth factors in CLL, we and others have detected that CLL B cells spontaneously produce multiple cytokines in vitro which may constitute an autocrine loop of RTK activation on the leukemic B cells. Moreover, aberrant expression and activation of non-RTKs, for example, Src/Syk kinases, induce resistance of the leukemic B cells to therapy. Based on current available knowledge, we detailed the impact of aberrant activities of various RTKs/non-RTKs on CLL B cell survival and the potential of using these signaling components as future therapeutic targets in CLL therapy.

In-vitro antitumor activity evaluation of hyperforin derivatives

The derivatives of hyperforin, namely hyperforin acetate (2), 17,18,22,23,27,28,32,33-octahydrohyperforin acetate (3), and N,N-dicyclohexylamine salt of hyperforin (4), have been investigated for their antitumor properties. In-vitro studies demonstrated that 2 and 4 were active against HeLa (human cervical cancer), A375 (human malignant melanoma), HepG2 (human hepatocellular carcinoma), MCF-7 (human breast cancer), A549 (human nonsmall cell lung cancer), K562 (human chronic myeloid leukemia), and K562/ADR (human adriamycin-resistant K562) cell lines with IC(50) values in the range of 3.2-64.1 μM. The energy differences between highest occupied molecular orbital and lowest unoccupied molecular orbital of 2-4 were calculated to be 0.39778, 0.43106, and 0.30900 a.u., respectively, using the Gaussian 03 software package and ab initio method with the HF/6-311 G* basis set. The result indicated that the biological activity of 4 might be the strongest and that of 3 might be the weakest, which was in accordance with their corresponding antiproliferative effects against the tested tumor cell lines. Compound 4 caused cell cycle arrest at G2/M phase in flow cytometry experiment and induced apoptosis by 4',6-diamidino-2-phenylindole staining and Annexin V-FITC/PI (propidium iodide) double-labeled staining in HepG2 cells. The results indicated a potential for N,N-dicyclohexylamine salt of hyperforin as a new antitumor drug.

Phase II trials of single-agent anti-VEGF therapy for patients with chronic lymphocytic leukemia

Between 2005 and 2008, we conducted separate phase II clinical testing of three distinct anti-VEGF therapies for patients with relapsed/refractory CLL. Collectively, 46 patients were accrued to trials of single-agent anti-VEGF antibody (bevacizumab, n = 13) or one of two receptor tyrosine kinase inhibitors (AZD2171, n = 15; sunitinib malate, n = 18). All patients have completed treatment. Patients received a median of two cycles of bevacizumab, AZD2171, or sunitinib malate. All three trials were closed early due to lack of efficacy. No complete or partial remissions were observed. Individually and collectively, these studies indicate that single-agent anti-VEGF therapy has minimal clinical activity for patients with relapsed/refractory CLL.

Functional genomics of endothelial cells treated with anti-angiogenic or angiopreventive drugs

Angiogenesis is a highly regulated physiological process that has been studied in considerable detail given its importance in several chronic pathologies. Many endogenous factors and hormones intervene in the regulation of angiogensis and classical as well as targeted drugs have been developed for its control. Angiogenesis inhibition has come off the bench and entered into clinical application for cancer therapy, particularly for metastatic disease. While the clinical benefit is currently in terms of months, preclinical data suggest that novel drugs and drug combinations could lead to substantial improvement. The many targets of endogenous angiogenesis inhibitors reflect the complexity of the process; in contrast, current clinical therapies mainly target the vascular endothelial growth factor system. Cancer chemopreventive compounds can retard tumor insurgence and delay or prevent metastasis and many of these molecules hinder angiogenesis, a mechanism that we termed angioprevention. Angiopreventive drugs appear to prevalently act through the inhibition of the pro-inflammatory and anti-apoptotic player NFkappaB, thus contrasting inflammation dependent angiogenesis. Relatively little is known concerning the effects of these angiogenesis inhibitors on gene expression of endothelial cells, the main target of many of these molecules. Here we provide an exhaustive list of anti-angiogenic molecules, and summarize their effects, where known, on the transcriptome and functional genomics of endothelial cells. The regulation of specific genes can be crucial to preventive or therapeutic intervention. Further, novel targets might help to circumvent resistance to anti-angiogenic therapy. The studies we review are relevant not only to cancer but also to other chronic degenerative diseases involving endothelial cells, such as cardiovascular disorders, diabetes, rheumatoid arthritis and retinopaties, as well as vessel aging.

Hyperforin inhibits P-gp and BCRP activities in chronic lymphocytic leukaemia cells and myeloid cells

We showed previously that hyperforin (HF), a natural phloroglucinol, stimulated apoptosis in B cell chronic lymphocytic leukaemia cells (CLL) and displayed anti-angiogenic properties. In the present work, we investigated the effects of hyperforin on the activity of P-gp/MDR1, an ABC (ATP-binding cassette) transporter putatively involved in multidrug resistance (MDR). Ex vivo treatment of CLL cells with HF markedly impaired the activity of P-gp, as measured by the inhibition of the capacity of the treated cells to efflux the rhodamine 123 probe. In addition, most CLL cells expressed breast cancer resistance protein (BCRP), another ABC transporter. The activity of BCRP was also inhibited by HF, as assessed by the impaired capacity of HF-treated CLL cells to efflux the specific probe mitoxantrone. The capacity of HF to reverse P-gp and BCRP activity was confirmed in myeloid leukaemia cell lines, notably in HL-60/DNR cells selected for their resistance to daunorubicine and overexpressing P-gp. Our results therefore suggest that HF might be of interest in the therapy of CLL and other haematological malignancies through its potential capacity to revert MDR in addition to its pro-apoptotic properties.

Cytotoxic effects of hyperatomarin, a prenylated phloroglucinol from Hypericum annulatum Moris subsp. annulatum, in a panel of malignant cell lines

The cytotoxic effects of hyperatomarin - a prenylated phloroglucinol isolated from Hypericum annulatum Moris subsp. annulatum were assessed in a broad spectrum of tumor cell lines originating from leukemias, lymphomas and solid malignancies. The tested compound exerted strong concentration-dependent cytotoxic effects (IC50 values ranging 0.14-15.7 μM), comparable to and even outclassing in some cell lines those of the established anti-cancer drug daunorubicin. Exposure of different human tumor cell lines to hyperatomarin resulted in strong mono- and oligo-nucleosomal fragmentation of genomic DNA, as evidenced by 'Cell death detection' ELISA kit and by DNA-electrophoresis, which unambiguously indicates that the induction of apoptosis is implicated in the cytotoxic mode of action of the tested compound.

The anti-angiogenic 8-epipuupehedione behaves as a potential anti-leukaemic compound against HL-60 cells

We have previously reported that 8-epipuupehedione, a synthetic derivative of sesquiterpenes found in several kinds of sponges, is a potent inhibitor of angiogenesis. Here, we show that 8-epipuupehedione is also a potent anti- leukaemic compound, targeting three hallmarks of malignancy: proliferation, survival and extra-cellular matrix re-modelling. To fulfil this goal, we use the HL-60 promyeolocytic cells as our model system and the following experimental procedures: cell growth assay, Hoetsch staining, cell cycle analysis and DNA fragmentation, caspase 3 activity and zymographic assays. Our results show that this compound inhibits proliferation and has potent and specific pro-apoptotic effects on HL-60 promyelocytic cells, inducing their nuclei and DNA fragmentation, as well as caspase 3 activity activation. Furthermore, 8-epipuupehedione strongly inhibits matrix metalloproteinase-2 and urokinase production by HL-60 cells. These results suggest that 8-epipuupehedione could be an attractive drug for further evaluation in the treatment of leukemia.

Hyperforin blocks neutrophil activation of matrix metalloproteinase-9, motility and recruitment, and restrains inflammation-triggered angiogenesis and lung fibrosis

Hyperforin (Hyp), a polyphenol-derivative of St. John's wort (Hypericum perforatum), has emerged as key player not only in the antidepressant activity of the plant but also as an inhibitor of bacteria lymphocyte and tumor cell proliferation, and matrix proteinases. We tested whether as well as inhibiting leukocyte elastase (LE) activity, Hyp might be effective in containing both polymorphonuclear neutrophil (PMN) leukocyte recruitment and unfavorable eventual tissue responses. The results show that, without affecting in vitro human PMN viability and chemokine-receptor expression, Hyp (as stable dicyclohexylammonium salt) was able to inhibit in a dose-dependent manner their chemotaxis and chemoinvasion (IC50=1 microM for both); this effect was associated with a reduced expression of the adhesion molecule CD11b by formyl-Met-Leu-Phe-stimulated neutrophils and block of LE-triggered activation of the gelatinase matrix metalloproteinase-9. PMN-triggered angiogenesis is also blocked by both local injection and daily i.p. administration of the Hyp salt in an interleukin-8-induced murine model. Furthermore, i.p. treatment with Hyp reduces acute PMN recruitment and enhances resolution in a pulmonary bleomycin-induced inflammation model, significantly reducing consequent fibrosis. These results indicate that Hyp is a powerful anti-inflammatory compound with therapeutic potential, and they elucidate mechanistic keys.

MMP-9 in B-cell chronic lymphocytic leukemia is up-regulated by alpha4beta1 integrin or CXCR4 engagement via distinct signaling pathways, localizes to podosomes, and is involved in cell invasion and migration

B-cell chronic lymphocytic leukemia (B-CLL) progression is determined by malignant cell extravasation and lymphoid tissue infiltration. We have studied the role and regulation of matrix metalloproteinase-9 (MMP-9) in B-CLL cell migration and invasion. Adhesion of B-CLL cells to the fibronectin fragment FN-H89, VCAM-1, or TNF-alpha-activated human umbilical vein endothelial cells (HUVECs) up-regulated MMP-9 production, measured by gelatin zymography. This effect was mediated by alpha4beta1 integrin and required PI3-K/Akt signaling. The chemokine CXCL12 also up-regulated MMP-9, independently of alpha4beta1 and involving ERK1/2 but not Akt activity. Accordingly, alpha4beta1 engagement activated the PI3-K/Akt/NF-kappaB pathway, while CXCL12/CXCR4 interaction activated ERK1/2/c-Fos signaling. Anti-MMP-9 antibodies, the MMP-9 inhibitor TIMP-1, or transfection with 3 different MMP-9 siRNAs significantly blocked migration through Matrigel or HUVECs. Cell-associated MMP-9 was mainly at the membrane and contained the proactive and mature forms. Moreover, B-CLL cells formed podosomes upon adhesion to FN-H89, VCAM-1, or fibronectin; MMP-9 localized to podosomes in a PI3-K-dependent manner and degraded a fibronectin/gelatin matrix. Our results are the first to show that MMP-9 is physiologically regulated by alpha4beta1 integrin and CXCL12 and plays a key role in cell invasion and transendothelial migration, thus contributing to B-CLL progression. MMP-9 could therefore constitute a target for treatment of this malignancy.

Hyperforin, a new lead compound against the progression of cancer and leukemia?

Extracts of the plant St John's wort, Hyperforin perforatum L., have been used for centuries in traditional medicine, notably for the treatment of depression. One of their main lipophilic components, a natural prenylated phloroglucinol termed hyperforin (HF), has been identified as the major molecule responsible for the antidepressant effects of this plant. Within the last few years, a number of studies have demonstrated that HF displays, in addition, several other biological properties of potential pharmacological interest. They include an antibacterial capacity and inhibitory effects on inflammatory mediators. It is worth noting that HF also promotes apoptosis of various cancer cells from solid tumors and hematological malignancies, including B-cell chronic lymphocytic leukemia. In addition, HF inhibits the capacity of migration and invasion of different tumor cells, as well as exhibiting antiangiogenic effects. Altogether, these properties qualify HF as a lead structure for the development of new therapeutic molecules in the treatment of various diseases, including some malignant tumors.

Inflammation dampened by gelatinase A cleavage of monocyte chemoattractant protein-3

Tissue degradation by the matrix metalloproteinase gelatinase A is pivotal to inflammation and metastases. Recognizing the catalytic importance of substrate-binding exosites outside the catalytic domain, we screened for extracellular substrates using the gelatinase A hemopexin domain as bait in the yeast two-hybrid system. Monocyte chemoattractant protein-3 (MCP-3) was identified as a physiological substrate of gelatinase A. Cleaved MCP-3 binds to CC-chemokine receptors-1, -2, and -3, but no longer induces calcium fluxes or promotes chemotaxis, and instead acts as a general chemokine antagonist that dampens inflammation. This suggests that matrix metalloproteinases are both effectors and regulators of the inflammatory response.