Shallow- and Deep-Water Ophiura Species Produce a Panel of Chlorin Compounds with Potent Photodynamic Anticancer Activities.

A Pacific brittle star Ophiura sarsii has previously been shown to produce a chlorin (3S,4S)-14-Ethyl-9-(hydroxymethyl)-4,8,13,18-tetramethyl-20-oxo-3-phorbinepropanoic acid (ETPA) (1) with potent phototoxic activities, making it applicable to photodynamic therapy. Using extensive LC-MS metabolite profiling, molecular network analysis, and targeted isolation with de novo NMR structure elucidation, we herein identify five additional chlorin compounds from O. sarsii and its deep-sea relative O. ooplax: 10S-Hydroxypheophorbide a (2), Pheophorbide a (3), Pyropheophorbide a (4), (3S,4S,21R)-14-Ethyl-9-(hydroxymethyl)-21-(methoxycarbonyl)-4,8,13,18-tetramethyl-20-oxo-3-phorbinepropanoic acid (5), and (3S,4S,21R)-14-Ethyl-21-hydroxy-9-(hydroxymethyl)-4,8,13,18-tetramethyl-20-oxo-3-phorbinepropanoic acid (6). Chlorins 5 and 6 have not been previously reported in natural sources. Interestingly, low amounts of chlorins 1-4 and 6 could also be identified in a distant species, the basket star Gorgonocephalus cf. eucnemis, demonstrating that chlorins are produced by a wide spectrum of marine invertebrates of the class Ophiuroidea. Following the purification of these major Ophiura chlorin metabolites, we discovered the significant singlet oxygen quantum yield upon their photoinduction and the resulting phototoxicity against triple-negative breast cancer BT-20 cells. These studies identify an arsenal of brittle star chlorins as natural photosensitizers with potential photodynamic therapy applications.

κ- and λ-Carrageenans from Marine Alga Chondrus armatus Exhibit Anticancer In Vitro Activity in Human Gastrointestinal Cancers Models.

The carrageenans isolated from red algae demonstrated a variety of activities from antiviral and immunomodulatory to antitumor. The diverse structure and sulfation profile of carrageenans provide a great landscape for drug development. In this study, we isolated, purified and structurally characterized κo- and λo- oligosaccharides from the marine algae Chondrus armatus. We further examined the tumor suppressive activity of both carrageenans in gastrointestinal cancer models. Thus, using MTT assay, we could demonstrate a pronounced antiproliferative effect of the carrageenans in KYSE-30 and FLO-1 as well as HCT-116 and RKO cell lines with IC50 184~405 µg/mL, while both compounds were less active in non-cancer epithelial cells RPE-1. This effect was stipulated by the inhibition of cell cycle progression in the cancer cells. Specifically, flow cytometry revealed an S phase delay in FLO-1 and HCT-116 cells under κo-carrageenan treatment, while KYSE-30 demonstrated a pronounced G2/M cell cycle delay. In line with this, western blotting revealed a reduction of cell cycle markers CDK2 and E2F2. Interestingly, κo-carrageenan inhibited cell cycle progression of RKO cells in G1 phase. Finally, isolated κo- and λo- carrageenans induced apoptosis on adenocarcinomas, specifically with high apoptosis induction in RKO cells. Overall, our data underline the potential of κo- and λo- carrageenans for colon and esophageal carcinoma drug development.

Marine Natural Products from the Russian Pacific as Sources of Drugs for Neurodegenerative Diseases.

Neurodegenerative diseases are growing to become one of humanity's biggest health problems, given the number of individuals affected by them. They cause enough mortalities and severe economic impact to rival cancers and infections. With the current diversity of pathophysiological mechanisms involved in neurodegenerative diseases, on the one hand, and scarcity of efficient prevention and treatment strategies, on the other, all possible sources for novel drug discovery must be employed. Marine pharmacology represents a relatively uncharted territory to seek promising compounds, despite the enormous chemodiversity it offers. The current work discusses one vast marine region-the Northwestern or Russian Pacific-as the treasure chest for marine-based drug discovery targeting neurodegenerative diseases. We overview the natural products of neurological properties already discovered from its waters and survey the existing molecular and cellular targets for pharmacological modulation of the disease. We further provide a general assessment of the drug discovery potential of the Russian Pacific in case of its systematic development to tackle neurodegenerative diseases.

Chlorin Endogenous to the North Pacific Brittle Star Ophiura sarsii for Photodynamic Therapy Applications in Breast Cancer and Glioblastoma Models.

Photodynamic therapy (PDT) represents a powerful avenue for anticancer treatment. PDT relies on the use of photosensitizers-compounds accumulating in the tumor and converted from benign to cytotoxic upon targeted photoactivation. We here describe (3S,4S)-14-Ethyl-9-(hydroxymethyl)-4,8,13,18-tetramethyl-20-oxo-3-phorbinepropanoic acid (ETPA) as a major metabolite of the North Pacific brittle stars Ophiura sarsii. As a chlorin, ETPA efficiently produces singlet oxygen upon red-light photoactivation and exerts powerful sub-micromolar phototoxicity against a panel of cancer cell lines in vitro. In a mouse model of glioblastoma, intravenous ETPA injection combined with targeted red laser irradiation induced strong necrotic ablation of the brain tumor. Along with the straightforward ETPA purification protocol and abundance of O. sarsii, these studies pave the way for the development of ETPA as a novel natural product-based photodynamic therapeutic.

Mining Natural Compounds to Target WNT Signaling: Land and Sea Tales.

WNT signaling plays paramount roles in organism development, physiology, and disease, representing a highly attractive target for drug development. However, no WNT-modulating drugs have been approved, with several candidates trudging through the early clinical trials. This delay instigates alternative approaches to discover WNT-modulating drugs. Natural products were the source of therapeutics for centuries, but the chemical diversity they offer, especially when looking at different taxonomic groups and habitats, is still to a large extent unexplored. These considerations urge researchers to screen natural compounds for the WNT-modulatory activities. Since several reviews on such endeavors exist, we here have attempted to present these efforts as "Land and sea tales" (citing the book title by Rudyard Kipling) superimposing them onto the traditional pipeline of drug discovery and early development. In doing so, we illustrate each step of the pipeline with case studies stemming from our own research. It will become obvious that several steps of the pipeline need to be modified when applied to natural products rather than to synthetic libraries. Yet the main message of this chapter is that natural compounds represent a powerful source for the WNT signaling modulators and can be developed towards drug candidates against WNT-dependent maladies.

Bioactive Compounds with Antiglioma Activity from Marine Species.

The search for new chemical compounds with antitumor pharmacological activity is a necessary process for creating more effective drugs for each specific malignancy type. This review presents the outcomes of screening studies of natural compounds with high anti-glioma activity. Despite significant advances in cancer therapy, there are still some tumors currently considered completely incurable including brain gliomas. This review covers the main problems of the glioma chemotherapy including drug resistance, side effects of common anti-glioma drugs, and genetic diversity of brain tumors. The main emphasis is made on the characterization of natural compounds isolated from marine organisms because taxonomic diversity of organisms in seawaters significantly exceeds that of terrestrial species. Thus, we should expect greater chemical diversity of marine compounds and greater likelihood of finding effective molecules with antiglioma activity. The review covers at least 15 classes of organic compounds with their chemical formulas provided as well as semi-inhibitory concentrations, mechanisms of action, and pharmacokinetic profiles. In conclusion, the analysis of the taxonomic diversity of marine species containing bioactives with antiglioma activity is performed noting cytotoxicity indicators and to the tumor cells in comparison with similar indicators of antitumor agents approved for clinical use as antiglioblastoma chemotherapeutics.

Transposons-Based Clonal Diversity in Trematode Involves Parts of CR1 (LINE) in Eu- and Heterochromatin.

Trematode parthenitae have long been believed to form clonal populations, but clonal diversity has been discovered in this asexual stage of the lifecycle. Clonal polymorphism in the model species Himasthla elongata has been previously described, but the source of this phenomenon remains unknown. In this work, we traced cercarial clonal diversity using a simplified amplified fragment length polymorphism (SAFLP) method and characterised the nature of fragments in diverse electrophoretic bands. The repetitive elements were identified in both the primary sequence of the H. elongata genome and in the transcriptome data. Long-interspersed nuclear elements (LINEs) and long terminal repeat retrotransposons (LTRs) were found to represent an overwhelming majority of the genome and the transposon transcripts. Most sequenced fragments from SAFLP pattern contained the reverse transcriptase (RT, ORF2) domains of LINEs, and only a few sequences belonged to ORFs of LTRs and ORF1 of LINEs. A fragment corresponding to a CR1-like (LINE) spacer region was discovered and named CR1-renegade (CR1-rng). In addition to RT-containing CR1 transcripts, we found short CR1-rng transcripts in the redia transcriptome and short contigs in the mobilome. Probes against CR1-RT and CR1-rng presented strikingly different pictures in FISH mapping, despite both being fragments of CR1. In silico data and Southern blotting indicated that CR1-rng is not tandemly organised. CR1 involvement in clonal diversity is discussed.

Antitumor potential of carrageenans from marine red algae.

Marine algae are abundant and inexhaustive sources of the bioactive compounds with the various benefits for human health. Among these substances an attention is given to the sulfated polysaccharides presented as the complexes of polymer macromolecules with excellent biological features including antioxidant, anti-inflammatory anticoagulant, antiviral, and immunomodulatory activities. In addition to the aforementioned properties there is a growing number of research results suggesting the bioactive sulfated polysaccharides such as carrageenan, fucoidan, laminarin, and others exert anticancer and antimetastatic properties. The present review contains the main results of experimental studies of the carrageenan anticancer activity including systemic and intracellular mechanisms of the antiproliferative influence. Relationships between structure, physico-chemical properties of carrageenan and their antitumor effects are described. There are data on the toxicology and pharmacokinetics of carrageenans as well as other aspects of their pharmacotherapeutic and pharmacoprophylactic influence that allow considering them as the potential anticancer agents.

Hydrogels based on modified pectins capable of modulating neural cell behavior as prospective biomaterials in glioblastoma treatment.

Glioblastoma is the most common malignant tumor of the brain, but its treatment outcomes can be improved by new therapeutic techniques using biocompatible materials. Utilizing controllable alkaline de-esterification we obtained pectin preparation with 27.4% esterification degree and used it for bio-artificial matrix production. We discovered optimal gelation conditions in the presence of Ca2+ by the analysis of visco-elastic properties of the gels and produced a series of biomaterials in hydrogel forms. Hydrogels based on low-esterified pectin significantly slow down the metabolism of C6 glioma cells and neural stem cells (NSCs) and slightly decrease the viability of the C6 glioma, but not of NSCs. This happens due to a decrease in cell proliferation rate, while apoptosis degrees remain stable or negligibly decrease. We created a set of pectin hydrogels supplemented with different ratios of two ECM proteins-collagens I and IV. We have shown that the formation of cell processes in glioma C6 can be regulated by varying the ratio of two ECM proteins in gels used for 3D cell cultivation. Thus, composite matrix materials obtained can be used for modeling brain tumor invasion. The results presented suggest that modified pectins supplemented with two collagen types may serve as prospective biomaterials for glioblastoma treatment due to their ability to regulate glioma cell dynamics.

Molecular determinants of the interaction between glioblastoma CD133+ cancer stem cells and the extracellular matrix.

Glioblastoma multiforme (GBM) is the most common primary tumor of the human brain. It is characterized by invasive growth and strong resistance to treatment, and the median survival time of patients is 15 months. The invasive growth of this tumor type is associated with tumor cells with an aggressive phenotype, while its treatment resistance is attributed to cancer stem cells (CSCs). It remains unclear if CSCs have a more invasive nature than differentiated glioblastoma cells (DGCs), and what contribution CSCs make to the aggressive phenotype of GBM. Interaction with the extracellular matrix (ECM) is a key factor in the development of invasion. The aim of the present study was to compare the expression levels of signaling pathway proteins involved in interaction of receptors with the ECM in CSCs and DGCs. The U-87MG GBM cell line was used in the present study CSCs were extracted from gliomaspheres through magnetic-activated cell sorting based on the expression of cluster of differentiation 133 (CD133); CD133-negative DCGs were used as a control. HPLC and mass spectrometry were also used, and biological and molecular functions, signaling pathways and protein-protein interactions were analyzed using publicly available databases. Increased expression levels of the following 10 proteins involved in interaction with the ECM were identified in CSCs, compared with expression levels in DGCs: COL6A1, COL6A3, FN1, ITGA2, ITGA5, ITGAV, ITGB1, ITGB3, LAMB1 and LAMC1. The proteome of CSCs was observed to have >2-fold higher expression of these key proteins, when compared with the DGC proteome. Increased expression levels of four proteins (FERMT2, LOXL2, HDAC2 and FBN1) involved in activating signaling in response to receptor interaction with the ECM was also observed, indicating that CSCs may have highly invasive nature. LOXL2 expression level was >9-fold higher in CSCs compared to DGCs, suggesting that this protein may have potential as an marker for CSCs and as a target for this cell type in GBM.

Proteins of Wnt signaling pathway in cancer stem cells of human glioblastoma.

RATIONALE: Glioblastoma multiforme (GBM) is the most aggressive primary glial brain tumor. The prognosis for GBM patients is not favorable, with the median survival time being 15 months. Its treatment resistance is associated with GBM cell population having cancer stem cells (CSCs). Wnt/ß-catenin signaling pathway is a strategically important molecular mechanism, providing proliferation of stem cells of all types. This study compares the expression levels of signaling pathway proteins in CD133(+) CSCs and CD133(-) differentiated glioblastoma cells (DGCs). MATERIALS AND METHODS: the present study used U-87MG cells of human glioblastoma, the material was tested for mycoplasma contamination. High-performance liquid chromatography (HPLC) mass spectrometry was used for proteome analysis. Biological and molecular functions, signaling pathways and protein-protein interactions were analyzed using free-access databases: PubMed, PANTHER, Gene Ontology, Swiss-Prot and KEGG. Protein-protein interactions (PPIs) were analyzed using the STRING database (version 10). RESULTS: There were identified 589 proteins with significantly changed expression in CD133+ CSCs, as compared with CD133-DGCs (P<0.05). Bioinformatics analysis allowed to attribute 134 differentially expressed proteins to 16 signaling pathways. A significant increase in expression of eight Wnt signaling pathway proteins (APC, CSNK1E, CSNK1A, CSNK2A2, CSNK2B, CTNNB1, DVL1, RUVBL) was detected, as well as four proteins of the non-canonical Wnt pathway-RHOA, ROCK2, RAC2, DAAM1. Special attention should be paid to ß-catenin (CTNNB1) with more than 13.98-fold increase of expression in CSCs and Disheveled-associated activator of morphogenesis 1 (DAAM1) with 6.15-fold higher upregulation level. CONCLUSION: proteins of Wnt/ß-catenin signaling cascade are a prospective target for regulating CSCs activity.

Transforming growth factor-ß mimics the key proteome properties of CD133- differentiated and CD133+ cancer stem cells in glioblastoma.

Glioblastoma multiforme is the most aggressive type of primary brain tumor in humans. Its invasive growth is associated with cluster of differentiation (CD)133 cancer stem cells (CSCs) and CD133- differentiated glioblastoma cells (DGCs) with aggressive phenotype, which are developed under the influence of transforming growth factor (TGF)-ß. The present study aimed to compare the proteomes of CD133 CSCs and CD133- DGCs stimulated by TGF-ß, as well as the expression levels of the main proteins responsible for activating the signaling pathway of receptor interactions with the extracellular matrix (ECM). The U87MG GBM cell line was used in this study. CSCs were extracted from gliomaspheres through magnetic-activated cell sorting based on the expression of CD133 (CD133); CD133- DCGs served as a control. CD133- DGCs of the U87-MG cell line were treated with 10ng/mL TGF-ß1, and cell proliferation and migration were analyzed via real-time quantitative microscopy. High-performance liquid chromatography mass spectrometry was used for proteome analysis. The results revealed 589 proteins with significantly changes in expression among CD133 CSCs compared with those in CD133- DGCs (P<0.05). Bioinformatics analysis allowed to attribute 134 differentially expressed proteins to 15 signaling pathways; among these proteins, 14 were involved in signaling cascades associated with the interaction between CSCs and the ECM, and were upregulated >twofold, while four proteins activated this signaling cascade. TGF-ß-stimulation increased the mobility, suppressed the proliferation and transformed the proteome profile of CD133- DGCs. Were identified 13 key proteins that activate the signaling pathway of receptor interaction with the ECM and three proteins activating this signaling pathway in CD133- DGCs which had the same values as those of CD133 CSCs. In conclusion, TGF-ß increased the expression of proteins that activate the signaling pathway of receptor interaction with the ECM in CD133- DGCs to the level of those in CD133 CSCs.

Pro-inflammatory modification of cancer cells microsurroundings increases the survival rates for rats with low differentiated malignant glioma of brain.

RATIONALE: Glioblastoma multiforme (GBM) is one of the most aggressive human brain tumors. The prognosis is unfavorable with a median survival of 15 months. GBM aggressive nature is associated with a special phenotype of cancer cells that develops because of the transforming growth factor ß (TGF-ß). The study was aimed at providing experimental justification in vivo of a possibility to suppress TGF-ß production in a tumor via pro-inflammatory modification of cancer cell microenvironment, using CD45+ mononuclear cells of the red bone marrow. MATERIALS AND METHODS: The experiment used animals with transplanted C6 glioma. The animals were divided into 4 groups: (I) control (N=60); (II) group of rats (N=30) that received granulocyte colony-stimulating factor (G-CSF) to recruit CD45+ bone marrow mononuclear cells into their systemic circulation (G-CSF group); (III) group of rats (N=30) that received pro-inflammatory therapy to trigger systemic inflammatory reaction by injecting bacterial lipopolysaccharides (LPS) and interferon-γ (IFNγ); (IV) rats (N=30), stimulated with G-CSF, followed by pro-inflammatory therapy. Stereotaxic modeling of a brain tumor in experimental animals, as well as a combination of morphological, immunocytochemical analyses and immunosorbent assay were used. RESULTS: TGF-ß1 production in the tumor tissue resulted being inversely proportional to the intensity of proliferation processes and directly proportional to the size of necrosis areas, peaking on the 28th day of the experiment. Stimulation of experimental animals with G-CSF recruits CD45+ mononuclear stem and progenitor cells into the systemic circulation of experimental animals with C6 glioma, accompanied by intensification of microglial proliferation in the tumor and infiltration of the tumor tissue with microglial cells. Pro-inflammatory therapy against G-CSF stimulation results in polarization of microglia/macrophages population together with intensified antigen presentation, lower production of TGF-ß and IL10, increased synthesis of pro-inflammatory cytokines TNFα and IL1 in the tumor lesion and adjacent brain matter, remodeling of tumor matrix and higher survival rates for the experimental animals. CONCLUSIONS: Pro-inflammatory inflammatory modification of cancer cell microenvironment suppresses TGFß production in a tumor and increases survival rates of the rats with transplanted poorly differentiated malignant brain glioma.

3-Bromofascaplysin is a prospective chemical compound for developing new chemotherapy agents in glioblastoma treatment.

Glioblastoma (GB) is one of the most aggressive human brain tumors. The prognosis is unfavorable, its treatment is relatively ineffective, and the median survival is about 15months. Medication development with new chemical compounds is one of the ways to solve the problem of current treatment inefficiency. This study is focused on the group of chemical substances, based on pentacyclic system of 12H-pyrido[1,2-a:3,4-b]diindole, and the most well-known part of this group is fascaplysin, first extracted from the sponge Fascaplysinopsis spp. We have synthesized a series of the following fascaplysin derivatives: 7-phenylfascaplysin, 3-chlorofascaplysin, 3-bromofascaplysin, 9-bromofascaplysin. The paper is aimed at analyzing the cytotoxic effect of these compounds on GB cells. MATERIALS AND METHODS: The study used rat glioma C6 cell line (ATCC®; cat no CCL-107), U-87MG cell line (ATCC; cat no. HTB-14™) and human glioblastoma T98-G cells (ATCC® CRL-1690™). Cell culture method, experimental pharmacological trials and γ-radiation in vitro, as well as flow cytofluorometry were used in the study. RESULTS: Cytotoxic effect of the tested compounds is stronger than the effect of unsubstituted fascaplysin, and appears to be dose-dependent and time-dependent. 3-bromofascaplysin is more efficient for cancer cells elimination, and by the end of the experiment the amount of living cancer cells in G0 phase remained at its lowest. Cytotoxic effect of 3-bromofascaplysin on glioblastoma T98-G cells is inferior to that of TMZ, and in case of preliminary radiation treatment of cancer cells with 48Gy the effect of the compound matches the TMZ treatment results. CONCLUSION: 3-Bromofascaplysin is a prospective chemical compound for development of new anti-cancer chemotherapeutic agents.

Personalized therapy and stem cell transplantation for pro-inflammatory modulation of cancer stem cells microenvironment in glioblastoma: Review.

Glioblastoma multiforme (GBM) is one of the most aggressive types of brain tumor in humans. The prognosis for patients with GBM is unfavorable and treatment is largely ineffective, where modern treatment regimens typically increase survival by 15 months. GBM relapse and progression are associated with cancer stem cells (CSCs). The present review provides a critical analysis of the primary reasons underlying the lack of effectiveness of modern CSC management methods. An emphasis is placed on the role of the blood-brain barrier in the development of treatment resistance. The existing methods for increasing the efficiency of antitumor genotoxic therapy are also described, and a strategy for personalized regulation of CSC based on post-genome technologies is suggested. The hypothesis that GBM cells employ a special mechanism for DNA repair based on their interactions with normal stem cells, is presented and the function of the tumor microenvironment in fulfilling the antitumor potential of normal stem cells is explained. Additionally, the mechanisms by which cancer stem cells regulate glioblastoma progression and recurrence are described based on novel biomedical technologies.

A Cytotoxic Porphyrin from North Pacific Brittle Star Ophiura sarsii.

Triple-negative breast cancer (TNBC) represents the deadliest form of gynecological tumors currently lacking targeted therapies. The ethanol extract of the North Pacific brittle star Ophiura sarsii presented promising anti-TNBC activities. After elimination of the inert material, the active extract was submitted to a bioguided isolation approach using high-resolution semipreparative HPLC-UV, resulting in one-step isolation of an unusual porphyrin derivative possessing strong cytotoxic activity. HRMS and 2D NMR resulted in the structure elucidation of the compound as (3S,4S)-14-Ethyl-9-(hydroxymethyl)-4,8,13,18-tetramethyl-20-oxo-3-phorbinepropanoic acid. Never identified before in Ophiuroidea, porphyrins have found broad applications as photosensitizers in the anticancer photodynamic therapy. The simple isolation of a cytotoxic porphyrin from an abundant brittle star species we describe here may pave the way for novel natural-based developments of targeted anti-cancer therapies.

The Anticancer Drug Discovery Potential of Marine Invertebrates from Russian Pacific.

Despite huge efforts by academia and pharmaceutical industry, cancer remains the second cause of disease-related death in developed countries. Novel sources and principles of anticancer drug discovery are in urgent demand. Marine-derived natural products represent a largely untapped source of future drug candidates. This review focuses on the anticancer drug discovery potential of marine invertebrates from the North-West Pacific. The issues of biodiversity, chemodiversity, and the anticancer pharmacophore diversity this region hides are consecutively discussed. These three levels of diversity are analyzed from the point of view of the already discovered compounds, as well as from the assessment of the overall, still undiscovered and enormous potential. We further go into the predictions of the economic and societal benefits the full-scale exploration of this potential offers, and suggest strategic measures to be taken on the national level in order to unleash such full-scale exploration. The transversal and multi-discipline approach we attempt to build for the case of marine invertebrate-based anticancer drug discovery from a given region can be applied to other regions and disease conditions, as well as up-scaled to global dimensions.

Addressing the Issue of Tetrodotoxin Targeting.

This review is devoted to the medical application of tetrodotoxin (TTX), a potent non-protein specific blocker of voltage-gated sodium (NaV) channels. The selectivity of action, lack of affinity with the heart muscle NaV channels, and the inability to penetrate the blood⁻brain barrier make this toxin an attractive candidate for anesthetic and analgesic drug design. The efficacy of TTX was shown in neuropathic, acute and inflammatory pain models. The main emphasis of the review is on studies focused on the improvement of TTX efficacy and safety in conjunction with additional substances and drug delivery systems. A significant improvement in the effectiveness of the toxin was demonstrated when used in tandem with vasoconstrictors, local anesthetics and chemical permeation enhancers, with the best results obtained with the encapsulation of TTX in microparticles and liposomes conjugated to gold nanorods.

Interaction of hematopoietic CD34+ CD45+ stem cells and cancer cells stimulated by TGF­ß1 in a model of glioblastoma in vitro.

The majority of modern treatment methods for malignant brain tumors are not sufficiently effective, with a median survival time varying between 9 and 14 months. Metastatic and invasive processes are the principal characteristics of malignant tumors. The most important pathogenic mechanism is epithelial­mesenchymal transition (EMT), which causes epithelial cells to become more mobile, and capable of invading the surrounding tissues and migrating to distant organs. Transforming growth factor­ß1 (TGF­ß1) serves a key role in EMT­inducing mechanisms. The current study presented the interaction between hematopoietic stem cells and glioblastoma cells stimulated by TGF­ß1 in vitro. The materials for the study were hematopoietic progenitor cell antigen CD34+ hematopoietic stem cells (HSCs) and U87 glioblastoma cells. Cell culture methods, automated monitoring of cell­cell interactions, confocal laser microscopy, flow cytometry and electron microscopy were used. It was demonstrated that U87 cells have a complex communication system, including adhesive intercellular contacts, areas of interdigitation with dissolution of the cytoplasm, cell fusion, communication microtubes and microvesicles. TGF­ß1 affected glioblastoma cells by modifying the cell shape and intensifying their exocrine function. HSCs migrated to glioblastoma cells, interacted with them and exchanged fluorescent tags. Stimulation of cancer cells with TGF­ß1 weakened the ability of glioblastoma cells to attract HSCs and exchange a fluorescent tag. This process stimulated cancer cell proliferation, which is an indication of the ability of HSCs to 'switch' the proliferation and invasion processes in glioblastoma cells.

Pharmacological Potential of Sea Cucumbers.

This review presents a detailed analysis of published research data focused on the pharmacological activity exerted by biologically active compounds isolated from sea cucumbers belonging to the class of Holothuroidea, phylum Echinodermata. The review contains descriptions of the structure, physico-chemical properties and pharmacological effects of these active substances. Particular attention is given to compounds with anticoagulant, antithrombotic, antioxidant, anticancer, anti-infectious, immune-stimulating and anti-ACE (angiotensin converting enzyme) activities as well as to the substances exerting a regulating influence on lipid and carbohydrate metabolism. All these compounds may be considered as prototypes for development of new pharmaceutical substances and medicines.