Rat Brain Tumor Cells Research Articles

Synthesis of (E)-7-arylidene-5-(hydroxy(aryl)methyl)bicyclo[3.2.0] heptan-6-one derivatives as anti-cancer agents

7,7-Dichlorobicyclo [3.2.0]heptan-6-one was prepared by adding dichloroketene to cyclopentene. Reduction of 7,7-dichlorobicyclo[3.2.0]heptan-6-one with Zn in acetic acid afforded the bicyclo[3.2.0]heptan-6-one. (E)-7-Arylidene-5-(hydroxy(aryl)methyl)bicyclo [3.2.0]heptan-6-ones were synthesized by addition of related benzaldehydes to bicyclo[3.2.0]heptan-6-one. The anti-proliferative activities of synthesized compounds were elucidated against rat brain tumor (C6) and human cervical carcinoma cells (HeLa) cell lines. The most active compound was chloro derivative against C6 cell lines with IC50 = 2.45 μM value (5-FU, IC50 = 14.82 μM). Moreover, the most active compound was methyl derivative against HeLa cell lines with IC50 = 26.30 μM (5-FU, IC50 = 29.30 μM).

Three new iridoids from the aerial parts of Nepeta teucriifolia Willd. and antiproliferative activities of extracts

The aerial parts of Nepeta teucriifolia Willd. were extracted with the solvents of different polarities. The antiproliferative activities of the extracts were evaluated against rat brain tumor (C6) and human cervix carcinoma (HeLa) cell lines. The phytochemical screening of the extracts was performed with TOF-LC/MS. The CH2Cl2 and EtOAc extracts showed considerable antiproliferative activities against HeLa cells at higher concentration (250 µg mL−1). The CH2Cl2 extract was found more active than the others on both cells. The phytochemical studies of the active extract led to the isolation of three new iridoids, teucriifolian A-C (1–3). The structure elucidations of the new compounds were performed using HPLC-TOF/MS, 1D and 2D NMR techniques. The compounds 1–3 were evaluated in terms of their antiproliferative activities against HeLa and C6 cells, respectively. The results indicated that only 2 had moderate antiproliferative activity against HeLa cells at 250 µg mL−1.

The antiproliferative and antioxidant activities of the essential oils of Juniperus species from Turkey

AbstractThe present study aimed to determine the essential oil compositions of four different types of Juniperus species including Juniperus oxycedrus ssp oxycedrus L., Juniperus foetidissima Willd., Juniperus excelsa M. Bieb, and Juniperus communis L. with their antioxidant and antiproliferative activities. The antiproliferative activity of the essential oils was determined against HeLa (human cervix carcinoma) and C6 (rat brain tumor cell) cell lines by BrdU cell proliferation assay. The essential oils were tested for their total reducing power activity, DPPH (2,2'‐diphenyl‐1‐picrylhydrazyl) free radical scavenging activities, and hydrogen peroxide scavenging activities. The overall results of the study showed that the needles of Juniperus species have strong antiproliferative activities as cell selective against C6 cells.

Synthesis, structural characterization, thermal behavior and cytotoxic/antiproliferative activity assessments of poly(maleic anhydride-alt-acrylic acid)/hydroxyurea polymer/drug conjugate

As drug carrier, poly(maleic anhydride-alt-acrylic acid) copolymer [poly(MA-alt-AA)], was prepared traditionally by radical initiated (benzoyl peroxide (BPO)), complex-radical polymerization technique via charge transfer complex (CTC) (50/50 in p-dioxane, at 70 °C under a nitrogen atmosphere). The pure alternating carrier was then conjugated as poly[MA-alt-AA]/HX (or MAAA/HX) copolymer/drug couple by ring opening reaction with an antineoplastic agent hydroxyurea (HX) for 48 h at 75 ± 0.1 °C in dimethylformamide (DMF), presence of triethylamine (Et3N) catalytic base. Chemical structure of the copolymer, antineoplastic agent and conjugate was characterized by Fourier Transform Infrared (ATR-FTIR) and also Nuclear Magnetic Resonance (proton and carbon NMR). Physical characterizations were also carried out by Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). To verify the elemental composition and also conjugation reaction of conjugated product, quantitative elemental analysis was especially carried out. Cytotoxicity was determined with Lactate Dehydrogenase (LDH) leakage assay using LDH cytotoxicity detection kit provided by Roche Diagnostics GMBH (Mannheim, Germany) based on the protocol in the user’s manual. Compared with 5-FU, toxicity values are as follows respectively: HX > MAAA > 5-FU ̴ MAAA/HX. Furthermore, antiproliferative activity studies was examined on HeLa (human cervical cancer) and (C6) rat brain tumor cells using proliferation BrdU ELISA assay. Conjugated-drug was identified to have the higher antiproliferation than the copolymer and free-drug (Hydroxyurea) on all studied concentrations and cellular potency of inhibitions were found as MAAA/HX > HX > MAAA at the highest concentration, 100 μg/mL. Toxic drug (HX) was modified as nontoxic MAAA/HX conjugate with good properties.

Anti-proliferative activity of ethyl acetate extracts of Tamarix gallica L. grown at different climatic conditions in Algeria

Abstract The aerial parts of T. gallica collected from three different locations (arid, humid and semi-arid) were extracted using ethyl acetate. The crude extracts were subjected to phenolic appraisal and antiproliferative activity using ELISA and xCELLigence assays. The total phenolic and flavonoids were evaluated using appropriate techniques to give a yield of total phenolics ranging between 238.46 and 348.56 mg GAE (Gallic acid equivalent)/g dry weight extract. The flavonoids yield was found to vary from 36.6 to 103.14 mg QE (quercetin equivalent)/g dry weight extract. Moreover, the extracts were tested against rat brain tumor (C6) and human cervix carcinoma (HeLa) cell lines and displayed important differences in activity. These disparities highlighted the effect of climatic factors as quality determinants of secondary metabolites and therefore as a key control of the biological therapeutic effect.

Antiproliferative and Antioxidant Activities of Two Extracts of the Plant Species Euphorbia dendroides L.

Background: These days, the desire for naturally occurring antioxidants has significantly increased, especially for use in foodstuffs, cosmetics, and pharmaceutical products, to replace synthetic antioxidants that are regularly constrained due to their carcinogenicity. Methods: The study in hand aimed to appraise the antioxidant effect of two Euphorbia dendroides extracts using reducing power, anti-peroxidation, and DPPH (1,1 Diphenyl 2 Pycril Hydrazil) scavenging essays, in addition to the anticancer activity against two tumor cell lines, namely C6 (rat brain tumor)cells, and Hela (human uterus carcinoma)cell lines. Results: The results indicated that the ethyl acetate extract exhibited antiradical activity of 29.49%, higher than that of n-butanol extract (18.06%) at 100 µg/mL but much lower than that of gallic acid (78.21%).The ethyl acetate extract exhibits better reducing capacity and lipid peroxidation inhibitory activity compared to n-butanol extract but less than all tested standards. Moreover, the ethyl acetate extract was found to have an antiproliferative activity of more than 5-FU (5-fluoro-Uracil) against C6 cells at 250 µg/mL with IC50 and IC75 of 113.97, 119.49 µg/mL, respectively, and good cytotoxic activity against the Hela cell lines at the same concentration. The HPLC-TOF-MS (high performance liquid chromatography-Time-of-flight-Mass Spectrometry) analyses exposed the presence of various compounds, among which Gallic and Chlorogenic acids functioned as major compounds. Conclusions: The two extracts exhibited moderate anticancer abilities and behaved somewhat as average antioxidant agents. Based on the total phenolics and flavonoids contents, as well as HPLC results, it could be concluded that antiproliferative and antioxidant activities depend upon the content of different phenolics and flavonoids.

Phytochemicals of Chrysophthalmum montanum (DC.) Boiss. Roots and Their Antiproliferative Activities Against HeLa and C6 Cell Lines

Pre-fractionation and contemporary spectroscopic analysis provides important clues with regard to synergistic and antagonistic effects as well as biological activities in complex multi-mixtures, especially natural products. Phytochemical contents of the Chrysophthalmum montanum root extracts were analyzed by gas chromatography–mass spectrometry and high performance liquid chromatography–time of flight/mass spectrometry. Furthermore, biological activity of root extract was investigated by antiproliferative efficiencies against human uterus carcinoma and rat brain tumor cells in vitro. The biological activity tests were carried out as dose-dependent assay using a multiwell spectrophotometer. 5-Fluorouracil was used as standard anticancer drug. Total 61 lipophilic components were identified quantitatively from the sub-fraction of n-hexane in which saturated fatty acids (33.06%), unsaturated fatty acids (21.03%) and other organic components (43.35%). Twenty three hydrophilic components, 16 phenolic and 7 flavonoid compounds, were quantified in the hydrophilic sub-fractions obtained from the C. montanum roots. Among the hydrophilic components, the vanillic acid was analyzed as 46.463 ± 0.167 mg compound/g dry extract in the sub-fraction dichloromethane. The linoleic acid was analyzed as a substantial component (8.13%) in the sub-fraction n-hexane. The highest antiproliferative activities were obtained from the sub-fraction dichloromethane against HeLa cells (IC50 = 36.53 μg/mL) and the sub-fraction n-hexane against C6 cells (IC50 = 11.98 μg/mL). No cytotoxic effect was observed from these sub-fractions.

Screening of some Juniperus extracts for the phenolic compounds and their antiproliferative activities

In this study, the needle and cone of Juniperus species (Juniperus oxycedrus L. subsp. oxycedrus, J. foetidissima Willd., J. excelsa Bieb. and J. communis L.) that are commonly used in Turkish folk medicine were investigated in terms of their phenolic contents and antiproliferative activities. The phenolic constituents of the extracts were determined by HPLC-TOF/MS. Antiproliferative activities of the species were investigated between 5 and 100μg/mL concentrations against human cervix carcinoma (HeLa) and rat brain tumor (C6) cell lines. Catechin and rutin were determined as the main phenolics of Juniperus species. Needle extracts exhibited better activities than cone extracts against HeLa and C6 cells. Needle of J. foetidissima exhibited high antiproliferative activities with an IC50 value of 10.65 against C6 cell lines. For HeLa cells, the highest antiproliferative activity was obtained with needle of J. communis with an IC50 value of 32.96. The results of the present study give a scientific basis to the traditional utilization of these Juniperus species, also demonstrating their potential as sources of natural anticancer compounds.

Synthesis and in vitro anticancer evaluation of 1,4-phenylene-bis-pyrimidine-2-amine derivatives

A series of 1,4-phenylene-bis-chalcones 3a-3h were synthesized by the reaction of terephthalaldehyde with substituted arylketones in this study. The novel 1,4-phenylene-bis-pyrimidine-2-amine derivatives 5a-5h were obtained by the addition of guanidine hydrochloride to 1,4-phenylene-bis-chalcone 3a-3h in ethanolic KOH under reflux conditions. The structure of the compounds was explained by means of IR, $^{1}$H NMR, $^{13}$C NMR, and elemental analyses. The anticancer activities of 3a-3h and 5a-5h were investigated against rat brain tumor cells and human uterus carcinoma in vitro$.$ Activity tests were performed as dose-dependent assays at eight concentrations. The positive control was 5-fluorouracil (5-FU). Compounds 3c and 3d were examined and they showed high activities as compared to 5-FU against C6 (rat brain tumor) and HeLa (human uterus carcinoma) cells. The anticancer activity of 5h was better than that of 5-FU at high concentrations cell-selectively against C6 cells.

Synthesis and anticancer and cytotoxic effects of novel 1,4-phenylene-bis-N-thiocarbamoylpyrazole and 1,4-phenylene-bis-pyrazolylthiazole derivatives

Thiazolylpyrazoline derivatives were recently reported as potent anticancer agents. In this study, novel 1,4-phenylene-bis-N-thiocarbamoylpyrazoles (3a-h and 1,4-phenylene-bis-pyrazolylthiazoles (5a-h were prepared and screened for their anticancer activities against C6 (rat brain tumor cells) and HeLa (human uterus carcinoma). Anticancer activity studies were performed as a dose-dependent assay starting with eight concentrations. 5-Fluorouracil (5-FU) was used as a positive control. Compounds 3c, 3d, and 3h were examined and they revealed almost the same activities compared with 5-FU in terms of cell selectivity against C6 cells. Moreover, compounds 3a-h had lower cytotoxicity than 5-FU. The low cytotoxicity values of 3a-h as well as their high antiproliferative activity were encouraging, but further studies are required on the use of these molecules as anticancer drugs.

Synthesis, structural characterization, and antiproliferative/cytotoxic effects of a novel modified poly(maleic anhydride-co-vinyl acetate)/doxorubicin conjugate

Drug carrier, poly(maleic anhydride-co-vinyl acetate) (MAVA or poly[MA-co-VA]) copolymer, was traditionally synthesized by free radical chain polymerization reaction, in methyl ethyl ketone (MEK) organic media at 80 °C, using benzoyl peroxide (BPO) as the radicalic initiator. The purified copolymer was then modified with a chemotherapeutic agent, doxorubicin hydrochloride (DOX) at 75 °C for 72 h, using N-(3-dimethyl-aminopropyl)-N′-ethylcarbodiimide hydrochloride (EDAC) as the carboxylic acid-activating agent. Structural characterization of the MAVA and the modified MAVA/DOX conjugate was carried out by Fourier transform infrared (FTIR) and nuclear magnetic resonance (1H-NMR and 13C-NMR). Their molecular weights were determined by size-exclusion chromatography (SEC). The spectroscopic and SEC results confirmed that conjugated/modification reaction was successfully carried out. UV spectrophotometric measurements indicated that MAVA/DOX preserved its molecular stability in physiological body fluid, PBS (physiological pH 7.40 at 37 °C). Antiproliferative activities of MAVA/DOX were determined by BrdU cell proliferation ELISA assay using C6 (Rat Brain tumor cells) and HeLa (human uterus carcinoma) cell lines in vitro by comparing with free DOX agent (reference compound). Although MAVA showed low antiproliferative activity, both MAVA/DOX and DOX exhibited greater activity against HeLa and C6. Lactate dehydrogenase (LDH) leakage assay was performed for MAVA/DOX and DOX, which detected a non-toxic effect against C6 even at the highest dose (100 μg/mL). IC50 and IC75 values were also determined using ED50 plus v1.0. Molecular modeling at M06-L/6-31 + G(d,p)//AM1 level showed that the electron density in MAVA/DOX is more localized resulting a higher polarization and thereby a higher dipole moment which shed light on the solubility of MAVA/DOX conjugate.

Synthesis and anticancer activities of 1,4-phenylene-bis-N-acetyl- and N-phenylpyrazoline derivatives

Novel 1,4-phenylene-bis-N-acetyl- (3a–h) and bis-N-phenylpyrazoline derivatives (4a–h) were obtained by addition of hydrazine hydrate and phenylhydrazine to bis-chalcone derivatives (1a–h) in acetic acid and acetic acid/ethanol for 4 and 8 h in reflux conditions, respectively. The structures of the obtained bis-N-acetylpyrazoline and bis-N-phenylpyrazoline derivatives were characterized by nuclear magnetic resonance (NMR) and infrared (IR) spectroscopic methods and elemental analysis. Compounds 3a–h and 4a–h were investigated to evaluate their anticancer activities against C6 (rat brain tumor cells) and HeLa (human uterus carcinoma) in vitro using a dose-dependent assay from 5 to 100 μM with 5-fluorouracil (5-FU) as standard anticancer drug. Compound 3a showed higher cell-selective activity compared with 5-FU against HeLa cells. Compounds 3a–h (except 3d) were shown to have better activities than 5-FU against both cells, particularly at high concentration. Compound 4c showed higher cell-selective activity compared with 5-FU against C6 cells. Compound 3a may be particularly promising as an anticancer drug against HeLa cells.

Antiproliferative effect of Cherry laurel

Cherry laurel (Prunus laurocerasus) fruits including phenolic and flavonoid contents are consumed as fresh, dried or prepared in marmalade and its leaves containing cyanogenic glycosides have healing activity of a well-known Anatolian folkloric remedy. Herein, Cherry laurel fruits were boiled in water for 2 h then extracted with hexane, EtOAc and BuOH successively. Antiproliferative activities of extracts were evaluated on HeLa (Human Cervix Carcinoma), HT29 (Human Colorectal Adenocarcinoma), C6 (Rat Brain Tumor Cells), and Vero (African Green Monkey Kidney) cell lines. All extracts exhibited slightly antiproliferative effects on various cancer cell lines at high concentration. We assessed the ability of extracts of cherry laurel fruit to devastate the membrane of cells. Results indicated that cherry laurel fruit extracts slightly destroys the cellular membrane in tumor cell lines at high concentration merely. The results of this study not support the efficacy of cherry laurel fruit extracts as an anticancer agent for cancer cells, but it suggests that cherry laurel fruit extracts may be used through reducing cytotoxicity a potential adjuvant therapy to current chemotherapeutic agents. Fatty acids of hexane extract were also determined by GC-MS analysis and found out that linoleic acid, palmitic acid and oleic acid were the major products.

Anticancer Activity of Papaver Somniferum

This work describes the pharmacological activity of extracts of Papaver somniferum , a poppy species. P. somniferum products are still considered as a unique source of drug for many diseases. The present study was designed to determine antiproliferative and cytotoxic effects of P. somniferum extracts on HeLa (Human Cervix Carcinoma), HT29 (Human Colorectal Adenocarcinoma), C6 (Rat Brain Tumor Cells), and Vero (African Green Monkey Kidney) cell lines. Alkaloids-rich extracts of P. somniferum exhibited antiproliferative effects on various cancer cell lines, especially at high concentrations. We assessed the ability of extracts of P. somniferum to harm the membrane of the cells. Results indicated that P. somniferum extracts destroy cellular membrane in tumor cell lines at high concentrations. Remarkably, the LDH test results disclosed that cytotoxicity of P. somniferum on cells was low at mid concentrations. This may indicate its cytostatic potential. The results of this study support the efficacy of P. somniferum extracts as an anticancer agent.

Studies on the Antioxidant and Antiproliferative Potentials ofCirsium arvensesubsp.vestitum

The antioxidant (DPPH, superoxide anion radical scavenging and FRAP) and antiproliferative activities against Vero cells (african green monkey kidney), C6 cells (rat brain tumor cells) and HeLa cells (human uterus carcinoma) of Cirsium arvense (CA) of all parts [root (Kinghorn et al. 2004), stem (CAS), flower (CAF) and leaves] and isolated compounds were investigated in vitro. CAR was shown to have the highest antiproliferative activity against HeLa and C6 cell lines as compared to other parts. A flavon glucoside (linarin), a steroid glucoside (daucosterin), a steroid (stigmasterol) and a new benzymidazole molecule (E−6-(3-(5,6-dimethoxy-1H-benzo[d] imidazol-2-yl)allyloxy)−5-(hydroxymethyl)-tetrahydro-2H-pyran-2,3,4-triol) were isolated from the CAR. The structures of these molecules were determined by the 13C (carbon) and 1H (proton)- Nuclear Magnetic Resonance (NMR), Fourier Transform Infrared Spectroscopy (FT-IR), and Gas Chromatography-Mass Spectrometry (GC-MS) techniques. CAR for C6 cell line, CAS for HeLa and Vero cell line were observed the highest antiproliferative activity. In addition, CAR showed the stronger DPPH activity than α-tocopherol and BHT at high concentrations. The FRAP and superoxide anion radical scavenging activities of CAR (Fr-7) were found to be higher than BHT. Practical Applications Cirsium species are considered as agricultural weed among villagers in Turkey and are used as alternative medicinal plant for years. Studies have shown that these species are rich with regard to bioactive seconder metabolites. There is no phytochemical/bioactivity study about this plant until now. Our findings showed that the extracts of this plant possessed potent antioxidant activities. Four compounds, one of which is a new one to literature, were isolated and characterized. Finally, Cirsium arvense, being considered as an invader plant in agricultural fields, can be evaluated as a good source of antioxidant products.

Chemical constituents and antiproliferative effects of cultured Mougeotia nummuloides and Spirulina major against cancerous cell lines.

In this study, the effect of Mougeotia nummuloides and Spirulina major on Vero cells (African green monkey kidney), C6 cells (rat brain tumor cells) and HeLa cells (human uterus carcinoma) was investigated in vitro. The antiproliferative effect of the methanol extract of M. nummuloides and S. major compared with 5-fluorourasil (5-FU) and cisplatin was tested at various concentrations using the BrdU Cell Proliferation ELISA. Both M. nummuloides and S. major extracts significantly inhibited the proliferation of Vero, HeLa and C6 cancer cell lines with IC50 and IC75 values. The M. nummuloides extract exhibited higher activity than 5-FU and cisplatin on Vero and C6 cells at high concentrations. The S. major extract revealed better antifproliferative activity than standards against Vero cells at 500 μg/mL. The compounds of methanol extracts were determined by GC-MS after the silylation process. Trehalose, monostearin and 1-monopalmitin were detected as major products in the M. nummuloides extract where as in the S. major extract; monostearin, 1-monopalmitin and hexyl alcohol were the main constituents.

Bioactivity-Guided Isolation of Antiproliferative Sesquiterpene Lactones from Centaurea solstitialis L. ssp. solstitialis.

Centaurea solstitialis L. ssp. solstitialis (CSS) has been used as medicine for various diseases. In this work, root, stem and flower parts of the plant were separately extracted with methanol to execute bioassay-guided isolation. Antiproliferative activities of each extracts on C6 cells (Rat Brain tumor cells) and HeLa cells (human uterus carcinoma) were investigated in vitro. The methanol extract of stem exhibited the most antiproliferative activity therefore isolation of active compounds was carried out for stem of the plant. Methanol extract of stem was boiled at 97 °C for 2 hours in water and then hexane and ethyl acetate were extracted sequentially. Solstitialin A 1 and 15-dechloro-15-hydroxychlorojanerin 2 were isolated from ethyl acetate extract by column chromatography and identified by spectroscopic techniques. Solstitialin A 1 was isolated from CSS and 15-dechloro-15-hydroxychlorojanerin 2 was isolated from Saussurea lipschitz and Rhaponticum pulchrum previously. These two compounds exhibited very high antiproliferative activity on C6 and HeLa cells. IC50 and IC75 values of compound 1 were obtained as 10.78 and 53.65 against C6 cell and as 48.78 and 68.52 against HeLa, respectively. IC50 and IC75 values of compound 2 were determined as 432.43 and 109.79 against C6 cell.

Antiproliferative activities of several plant extracts from Turkey on rat brain tumor and human cervix carcinoma cell lines

Turkey has a wide range of flora and fauna due to its climatic diversity. Medicinal plants from Turkey have been used since ancient times for their primary health care. In this study, we examined antiproliferative activities of the extracts from Crataegus monogyna, Vitis vinifera, Glycrrhiza glabra, Alnus glutinosa L. gaertn, and Alcea rosea against rat brain tumor (C6) and human cervical cancer (HeLa) cell lines. The results were compared with the standard anticancer drugs 5-Flurouracil (5-FU) and Cisplatin. C. monogyna, V. vinifera and A. rosea exhibited better antiproliferative activity than 5-FU and cisplatin at 100-75 µg/mL concentrations, against C6 cell lines. On the other hand, C. monogyna and V. vinifera extracts showed considerable antiproliferative activity against HeLa cells compared with 5-FU and cisplatin at 100-75 µg/mL. It can be suggested that, C. monogyna, A. glutinosa L. gaertn, V. vinifera and A. rosea extracts could be developed as an anticancer drug.

Biochanin A inhibits endothelial cell functions and proangiogenic pathways: implications in glioma therapy.

Malignant gliomas, such as glioblastoma multiforme, are highly vascularized tumors of the central nervous system. A rich network of angiogenic vessels supporting glioma growth is an important therapeutic target in glioma therapy. In the past few years, small molecules have gained interest as multitargeting therapies for cancer. Biochanin A is a small, natural dietary isoflavone known for its anticancer potential. Previously, we have found that biochanin A inhibits invasion in human glioblastoma cells. In this study, we elucidated the antiangiogenic mechanisms of biochanin A using rat brain tumor (C6) and murine brain endothelial (bEnd.3) cells and an ex-vivo chick chorioallantoic membrane model. Biochanin A inhibited endothelial cell functions such as cell viability, migration, and invasion, as analyzed using MTT, scratch wound, and gelatin zymography assays. Activation of proangiogenic proteins (ERK/AKT/mTOR) was inhibited. Biochanin A also inhibited chemical hypoxia-inducible factor-1α and vascular endothelial growth factor in C6 cells. Results of chick chorioallantoic membrane assay showed that biochanin A inhibited blood vessel formation ex vivo. As these results suggest that biochanin A directly targets different facets of angiogenesis in vitro and ex vivo, this study provides a rationale for future preclinical evaluation of its efficacy against angiogenic gliomas.

Distinctive responses of brain tumor cells to TLR2 ligands:

Malignant brain tumor mass contains significant numbers of infiltrating glial cells that may intimately interact with tumor cells and influence cancer treatments. Understanding of characteristic discrepancies between normal GLIA and tumor cells would, therefore, be valuable for improving anticancer therapeutics. Here, we report distinct differences in toll-like receptors (TLR)-2-mediated responses between normal glia and primary brain tumor cell lines. We found that tyrosine phosphorylation of STAT1 by TLR2 ligands and its downstream events did not occur in mouse, rat, or human brain tumor cell lines, but were markedly induced in normal primary microglia and astrocytes. Using TLR2-deficient, interferon (IFN)-γ-deficient, and IFNγ-receptor-1-deficient mice, we revealed that the impaired phosphorylation of STAT1 might be linked with defective TLR2 system in tumor cells, and that a TLR2-dependent pathway, not IFNγ-receptor machinery, might be critical for tyrosine STAT1 phosphorylation by TLR2 ligands. We also found that TLR2 and its heterodimeric partners, TLR1 and 6, on brain tumor cells failed to properly respond to TLR2 ligands, and representative TLR2-dependent cellular events, such as inflammatory responses and cell death, were not detected in brain tumor cells. Similar results were obtained in in vitro and in vivo experiments using orthotopic mouse and rat brain tumor models. Collectively, these results suggest that primary brain tumor cells may exhibit a distinctive dysfunction of TLR2-associated responses, resulting in abnormal signaling and cellular events. Careful targeting of this distinctive property could serve as the basis for effective therapeutic approaches against primary brain tumors.