Isolation of Secondary Metabolites from Achillea grandifolia Friv. (Asteraceae) and Main Compounds' Effects on a Glioblastoma Cellular Model.

This study aims at the isolation and structural determination of the secondary metabolites of the herbaceous perennial plant Achillea grandifolia Friv. (Asteraceae). The examination of the non-volatile content of the leaves and flowers of A. grandifolia afforded the isolation of sixteen secondary metabolites. On the basis of NMR spectra, the identified compounds included ten sesquiterpene lactones; three guaianolides-rupicolin A (1), rupicolin B (2), and (4S,6aS,9R,9aS,9bS)-4,6a,9-trihydroxy-9-methyl-3,6-dimethylene-3a,4,5,6,6a,9,9a,9b-octahydro-3H-azuleno [4,5-b]furan-2-one (3); two eudesmanolides-artecalin (4) and ridentin B (5); two sesquiterpene methyl esters-(1S,2S,4αR,5R,8R,8αS)-decahydro-1,5,8-trihydroxy-4α,8-dimethyl-methylene-2-naphthaleneacetic acid methylester (6) and 1ß, 3ß, 6α-trihydroxycostic acid methyl ester (7); three secoguaianolides-acrifolide (8), arteludovicinolide A (9), and lingustolide A (10); and an iridoid-loliolide (11). Moreover, five known flavonoids, i.e., apigenin, luteolin, eupatolitin, apigenin 7-O-glucoside, and luteolin 7-O-glucoside (12-16) were also purified from the aerial parts of the plant material. We also investigated the effect of rupicolin A (1) and B (2) (main compounds) on U87MG and T98G glioblastoma cell lines. An MTT assay was performed to define cytotoxic effects and to calculate the IC50, while flow cytometry was employed to analyze the cell cycle. The IC50 values of reduced viability during the 48 h treatment for compound (1) and (2) were 38 µM and 64 µM for the U87MG cells and 15 µM and 26 µM for the T98G cells, respectively. Both rupicolin A and B induced a G2/M cell cycle arrest.

Intraoperative Flow Cytometry for the Evaluation of Meningioma Grade.

Meningiomas are the most frequent central nervous system tumors in adults. The majority of these tumors are benign. Nevertheless, the intraoperative identification of meningioma grade is important for modifying surgical strategy in order to reduce postoperative complications. Here, we set out to investigate the role of intraoperative flow cytometry for the differentiation of low-grade (grade 1) from high-grade (grade 2-3) meningiomas. The study included 59 patients. Intraoperative flow cytometry analysis was performed using the 'Ioannina Protocol' which evaluates the G0/G1 phase, S-phase, mitosis and tumor index (S + mitosis phase fraction) of a tumor sample. The results are available within 5 min of sample receipt. There were 41 grade 1, 15 grade 2 and 3 grade 3 meningiomas. High-grade meningiomas had significantly higher S-phase fraction, mitosis fraction and tumor index compared to low-grade meningiomas. High-grade meningiomas had significantly lower G0/G1 phase fraction compared to low-grade meningiomas. Thirty-eight tumors were diploids and twenty-one were aneuploids. No significant difference was found between ploidy status and meningioma grade. ROC analysis indicated 11.4% of tumor index as the optimal cutoff value thresholding the discrimination between low- and high-grade meningiomas with 90.2% sensitivity and 72.2% specificity. In conclusion, intraoperative flow cytometry permits the detection of high-grade meningiomas within 5 min. Thus, surgeons may modify tumor removal strategy.

Siderol Inhibits Proliferation of Glioblastoma Cells and Acts Synergistically with Temozolomide.

Glioblastoma (GBM) is the most aggressive primary central nervous system (CNS) tumor in adults with dismal prognosis. Currently, the therapeutic interventions include gross total resection, when possible, followed by radiotherapy and chemotherapy. However, despite treatment, tumor usually recurs within 7-9 months. The presence of glioma cells with stem-like properties and tumor's heterogeneity have been identified as the most important factors driving recurrence. Recently, research efforts have been focused on the use of natural substances as treatment for GBM. Siderol is an ent-kaurane diterpenoid, isolated from the genus Sideritis. Sideritis extracts have already been investigated for their anti-inflammatory, antioxidant, and anticancer effects. In this study, we investigated the antitumoral effects of siderol in GBM T98 and U87 cell lines, as well as the effects of combined treatment with temozolomide (TMZ). Cell viability was evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and trypan blue exclusion assay. Different concentrations of siderol were used in order to calculate the IC50 values at 72 h after treatment. Flow cytometry used for the DNA cell cycle analysis after treatment with siderol in concentrations of IC50 and twice the IC50 values for 72 h. Furthermore, the effect of siderol in cell's migratory ability was tested using wound healing assay. Cell viability and proliferation, after combined treatment with siderol and TMZ, also were evaluated with the trypan blue exclusion assay and the effects of the combination treatment were analyzed with CompuSyn software. Treatment with siderol significantly reduced cell viability in T98 and U87 cell lines in a dose-dependent manner and IC50 values were calculated, 18 µM and 13 µM, respectively. Moreover, siderol induced G0/G1 cell cycle arrest in a dose-dependent manner and inhibited the migration in both cell lines. In addition, siderol and TMZ seem to have synergistic action in the majority of tested concentrations in both T98 and U87 cells. In conclusion, siderol may represent an innovative strategy for the treatment of GBM, and further studies are needed on siderol's efficacy and mode of action.

Treatment of Merkel Cell Carcinoma Using Intraoperative Flow Cytometry (iFC) Protocol, Optimized for Head and Neck Lesions, as a Means for Tumor Margin Evaluation - a Case Presentation.

Background: We present the case of a patient with a Merkel cell carcinoma (MCC) of the left preauricular area. Case presentation:A 84-year-old Greek man was examined at the outpatient ENT Department of our clinic with a lesion in the preauricular area that had appeared four months ago. The patient history included antihypertensive and antihyperlipidemic therapy as well as treatment for dementia. The excision of the skin lesion was performed under local anesthesia. The histological examination revealed a Merkel cell carcinoma. The patient underwent a computed tomography (CT) scan that showed a lesion with clear limits in the left parotid gland and lymph nodes. Under general anesthesia, he underwent a left superficial parotidectomy, left submandibular gland excision and radical neck dissection. Histological preparations were analyzed using an intraoperative flow cytometry (iFC) protocol. A radiation therapy concluded the patient's treatment. Conclusion:Even if MCC appears as a less common and more aggressive skin cancer type, a clinician always has to include it in the differential diagnosis of a skin lesion. We found the use of iFC very useful for the diagnosis of this skin cancer.

An NF-κB- and Therapy-Related Regulatory Network in Glioma: A Potential Mechanism of Action for Natural Antiglioma Agents.

High-grade gliomas are among the most aggressive malignancies, with significantly low median survival. Recent experimental research in the field has highlighted the importance of natural substances as possible antiglioma agents, also known for their antioxidant and anti-inflammatory action. We have previously shown that natural substances target several surface cluster of differentiation (CD) markers in glioma cells, as part of their mechanism of action. We analyzed the genome-wide NF-κB binding sites residing in consensus regulatory elements, based on ENCODE data. We found that NF-κB binding sites reside adjacent to the promoter regions of genes encoding CD markers targeted by antiglioma agents (namely, CD15/FUT4, CD28, CD44, CD58, CD61/SELL, CD71/TFRC, and CD122/IL2RB). Network and pathway analysis revealed that the markers are associated with a core network of genes that, altogether, participate in processes that associate tumorigenesis with inflammation and immune evasion. Our results reveal a core regulatory network that can be targeted in glioblastoma, with apparent implications in individuals that suffer from this devastating malignancy.

Curcumin and Radiotherapy Exert Synergistic Anti-Glioma Effect In Vitro.

Curcumin, a bioactive polyphenol, is known to have anticancer properties. In this study, the effectiveness of curcumin pretreatment as a strategy for radio-sensitizing glioblastoma cell lines was explored. For this, U87 and T98 cells were treated with curcumin, exposed to 2 Gy or 4 Gy of irradiation, and the combined effect was compared to the antiproliferative effect of each agent when given individually. Cell viability and proliferation were evaluated with the trypan blue exclusion assay and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The synergistic effects of the combination treatment were analyzed with CompuSyn software. To examine how the co-treatment affected different phases of cell-cycle progression, a cell-cycle analysis via flow cytometry was performed. Treatment with curcumin and radiation significantly reduced cell viability in both U87 and T98 cell lines. The combination treatment arrested both cell lines at the G2/M phase to a higher extent than radiation or curcumin treatment alone. The synergistic effect of curcumin when combined with temozolomide resulted in increased tumor cell death. Our results demonstrate for the first time that low doses of curcumin and irradiation exhibit a strong synergistic anti-proliferative effect on glioblastoma cells in vitro. Therefore, this combination may represent an innovative and promising strategy for the treatment of glioblastoma, and further studies are needed to fully understand the molecular mechanism underlying this effect.

The Past, Present and Future of Flow Cytometry in Central Nervous System Malignancies.

Central nervous system malignancies (CNSMs) are categorized among the most aggressive and deadly types of cancer. The low median survival in patients with CNSMs is partly explained by the objective difficulties of brain surgeries as well as by the acquired chemoresistance of CNSM cells. Flow Cytometry is an analytical technique with the ability to quantify cell phenotype and to categorize cell populations on the basis of their characteristics. In the current review, we summarize the Flow Cytometry methodologies that have been used to study different phenotypic aspects of CNSMs. These include DNA content analysis for the determination of malignancy status and phenotypic characterization, as well as the methodologies used during the development of novel therapeutic agents. We conclude with the historical and current utility of Flow Cytometry in the field, and we propose how we can exploit current and possible future methodologies in the battle against this dreadful type of malignancy.

Haloperidol Induced Cell Cycle Arrest and Apoptosis in Glioblastoma Cells.

Although several antipsychotic drugs have been shown to possess anticancer activities, haloperidol, a "first-generation" antipsychotic drug, has not been extensively evaluated for potential antineoplastic properties. The aim of this study was to investigate the antitumoral effects of haloperidol in glioblastoma (GBM) U87, U251 and T98 cell lines, and the effects of combined treatment with temozolomide (TMZ) and/or radiotherapy, using 4 Gy of irradiation. The viability and proliferation of the cells were evaluated with trypan blue exclusion assay and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Apoptosis, using the annexin-propidium iodide (PI), and cell cycle, cluster of differentiation (CD) expression and caspase-8 activation were measured using flow cytometry. Treatment with haloperidol significantly reduced cell viability in U87, U251 and T98 GBM cell lines. Haloperidol induced apoptosis in a dose-dependent manner, inhibited cell migration and produced an alteration in the expression of CD24/CD44. The additional effect of haloperidol, combined with temozolomide and radiation therapy, increased tumor cell death. Haloperidol was observed to induce apoptosis and to increase caspase-8 activation. In conclusion, haloperidol may represent an innovative strategy for the treatment of GBM and further studies are warranted in glioma xenograft models and other malignancies.

Deglucohellebrin: A Potent Agent for Glioblastoma Treatment.

BACKGROUND: Glioblastoma is the most common primary brain tumor in adults with a dismal prognosis. To date, several anticancer agents have been isolated from plants. Helleborus odorus subsp. Cyclophyllus is an endemic plant of the Balcan flora. Herewith, we investigated for the first time, the anti-glioma effect of deglucohellebrin (DGH) extracted from the roots of Helleborus. METHODS: We investigated the effect of DGH in U251MG, T98G and U87G glioblastoma cell lines. We selected the T98G cells because of their inherent temozolomide resistance. RESULTS: The IC50 value of reduced viability for DGH was 7x10-5M in U251MG cells, 5x10-5M for the T98G cells and 4x10-5M in U87G cells during 72h treatment. DGH induced G2/M cell cycle arrest, caspace-8 activation and significant mitochondrial membrane depolarization, suggesting the activation of the intrinsic, mitochondrial- dependent apoptotic pathway. DGH and temozolomide induced changes in CDs' expression in U251MG and T98G cells. In zebrafish, DGH did not induce toxicity or behavioral alterations. CONCLUSION: The present study is the first to determine the anti-glioma activity of DGH. DGH may be a potent agent for glioblastoma treatment and further studies are needed.

Past, Present and Future of Flow Cytometry in Breast Cancer - A Systematic Review.

Breast cancer is the most common malignancy in women worldwide. In this systematic review 28 studies were taken into account, in order to evaluate the role of DNA content and cell cycle phases, measured by flow cytometry in breast cancer. Presence of aneuploidy and S-phase fraction have been extensively studied as a prognostication tool. With the current dawn of the age of intraoperative flow cytometry the present systematic review provide an insight of the current role of flow cytometry in breast cancer and future horizons.

Combination treatment for glioblastoma with temozolomide, DFMO and radiation.

PURPOSE: Glioblastoma multiforme (GBM) is the most malignant primary brain tumor with dismal prognosis. This tumor is characterized by extensive heterogeneity, thus is difficult to treat and every established or new treatment faces significant hazard of resistance. Temozolomide (TMZ), an oral alkylating agent, is the first-line treatment for GBM, but resistance to TMZ is a major problem. Herewith, we investigated the combined effect of TMZ, difluoromethylornithine (DFMO), an inhibitor of ornithine decarboxylase, and radiation in GBM cell lines. METHODS: We used the U87G, U251MG and T98G GBM cell lines. A linac 6MV accelerator (Varian Medical Systems) was used for cell irradiation. Viability and proliferation of the cells were examined with trypan blue exclusion assay, crystal violet and xCELLigence system. Cell cycle and activation of caspase-8 were evaluated with flow cytometry. RESULTS: The combination treatment resulted in a consistent higher suppression of proliferation in all cell lines treated and induced a significant higher cell cycle arrest in G2/M phase in U251MG and T98G cell lines. In U251MG cells caspase-8 was increased with each treatment alone, however the combination treatment had lower level of caspase-8 induction, suggesting a co-existence of another mechanism of cell death apart from apoptosis. In T98G cells the combination treatment increased the activation of caspase-8. CONCLUSION: Combination treatment with DFMO, TMZ and radiation significantly reduced cell viability in all cell lines tested. Given that both TMZ and DFMO can be administered orally and are related to minimal toxicities, this combination treatment may be a novel treatment strategy for GBM that deserves further investigation.

N-(p-coumaroyl) serotonin induces cell cycle arrest and apoptosis in breast cancer cells.

PURPOSE: Breast cancer is the most commonly diagnosed malignancy among women. Breast cancer cells may develop resistance to current chemotherapy, thus new chemotherapeutic agents are urgently needed. METHODS: A major number of drugs with anticancer activity have been isolated from plants. Herewith, we investigated for the first time the effect of N-(p-coumaroyl) serotonin (CS), isolated from Centaurea seed on a drug-resistant breast carcinoma (MCF-7) cells. Viability and proliferation of the cells were examined with trypan blue exclusion assay and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Caspace-8, cell cycle, and CD24/CD44/CD56/ CD58/CD71/CD15 expression were tested with flow cytometry. RESULTS: Treatment with CS significantly reduced cell viability. Induction of cell death and cell cycle arrest was confirmed with flow cytometry. After treatment with CS, there was a dose-dependent decrease in CD24/CD44/CD58/CD71 expression, whereas there was no change in CD56 and CD15 expression. CONCLUSION: The treatment of breast cancer cells with CS may represent a novel therapeutic strategy and requires further investigation.

Antiproliferative and cytotoxic action of N-(p-coumaroyl) serotonin in lung cancer cells.

PURPOSE: Lung cancer is among the leading causes of cancer-related cases and cancer-associated deaths. Tumor cells frequently acquire chemoresistance and, due to that, new therapies are always needed in the fight against cancer. Pharmaceutical plants continue to offer novel compounds as anticancer therapies. METHODS: We studied the action of N-p-coumaroyl-serotonin (CS), a natural compound from Centaurea seed and safflower on a lung adenocarcinoma cell line. Cytotoxic or antiproliferative effect was studied using the MTT assay. Cell cycle, caspase-8 activation, mitochondrial membrane potential (MMP) and expression of CD15/CD56/CD24/CD44/CD58/CD71 were studied by flow cytometry. RESULTS: CS exterted antiproliferative and cytotoxic activity, independent of mitochondrial membrane disruption. This compound caused S phase arrest and a decrease in the expression of CD24/CD44/CD58/CD71. CONCLUSION: This is the first report on the in vitro action of CS against lung cancer, necessitating further studies towards its use as a potential anticancer agent.

Moschamine inhibits proliferation of glioblastoma cells via cell cycle arrest and apoptosis.

Glioblastoma is the most common and most malignant primary brain tumor with a median survival of 15 months. Moschamine is an indole alkaloid that has a serotoninergic and cyclooxygenase inhibitory effect. In this study, we sought to determine whether moschamine could exert cytotoxic and cytostatic effects on glioma cells in vitro. Moschamine was tested for toxicity in zebrafish. We investigated the effect of moschamine on U251MG and T98G glioblastoma cell lines. Viability and proliferation of the cells were examined with trypan blue exclusion assay, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, and the xCELLigence system. Apoptosis (annexin-propidium iodide), cell cycle, and CD24/CD44/CD56/CD15 expression were tested with flow cytometry. Treatment with moschamine significantly reduced cell viability in both cell lines tested. Induction of cell death and cell cycle arrest was confirmed with flow cytometry in both cell lines. After treatment with moschamine, there was a dose-dependent decrease in CD24 and CD44 expression, whereas there was no change in CD56 and CD15 expression in T98G cell line. The zebrafish mortality on the fifth post-fertilization day was zero even for 1 mM of moschamine concentration. The treatment of glioblastoma cell lines with moschamine may represent a novel strategy for targeting glioblastoma.

N-(p-coumaroyl) serotonin inhibits glioblastoma cells growth through triggering S-phase arrest and apoptosis.

Glioblastoma is the most common and most malignant primary brain tumor with a median survival of 15 months. N-(p-coumaroyl) serotonin (CS) is an indole alkaloid with antioxidant, cardioprotective effects after ischemia and antitumor activity. In the present study we sought to determine whether could exert cytotoxic and cytostatic effects in glioma cells in vitro. CS was tested for toxicity in zebrafish. We investigated the effect of CS in U251MG and T98G glioblastoma cell lines. Viability and proliferation of the cells were examined with trypan blue exclusion assay and the xCELLigence system. Cell cycle, activation of caspase-8, mitochondrial membrane potential and CD24/CD44/CD56/CD15/CD71 expression were tested with flow cytometry. Treatment with CS significantly reduced cell viability in both cell lines tested. Induction of cell death and cell cycle arrest at G2/M and S-phase was confirmed with flow cytometry in both cell lines. CS produced significant higher activity of caspase-8 compared to control. After treatment with CS there was a dose-dependent increase in CD15 and CD71 expression, whereas there was no change in CD24/CD44/CD56 expression in both cell lines. The zebrafish mortality on the fifth post fertilization day was zero for even 1 mM of CS concentration. The treatment of glioblastoma cell lines with CS may represent a novel strategy for targeting glioblastoma. Further studies are obviously needed to elucidate the complete mechanism of its antitumor activity.

99mTc-Tetrofosmin Uptake Correlates with the Sensitivity of Glioblastoma Cell Lines to Temozolomide.

99mTc-tetrofosmin (99mTc-TF) is a single-photon emission computed tomography tracer that has been used for brain tumor imaging. The aim of the study was to assess if 99mTc-TF uptake by glioblastoma cells correlates with their response to temozolomide (TMZ). We investigated the correlation of TMZ antitumor effect with the 99mTc-TF uptake in two glioblastoma cell lines. The U251MG cell line is sensitive to TMZ, whereas T98G is resistant. Viability and proliferation of the cells were examined by trypan blue exclusion assay and xCELLigence system. Cell cycle was analyzed with flow cytometry. The radioactivity in the cellular lysate was measured with a gamma scintillation counter. TMZ induced G2/M cell cycle arrest in U251MG cells, whereas there was no effect on cell cycle in T98G cells. Lower 99mTc-TF uptake was observed in U251MG cells that were exposed to TMZ compared to control (P = 0.0159). No significant difference in respect to 99mTc-TF uptake was found in T98G cells when exposed to TMZ compared to control (P = 0.8). With 99mTc-TF, it was possible to distinguish between TMZ-sensitive and resistant glioblastoma cells within 6 h of treatment initiation. Thus, 99mTc-TF uptake may consist a novel approach to assess an early response of glioblastoma to chemotherapy and deserves further investigation.

Deferiprone Enhances Temozolomide Cytotoxicity in Glioma Cells.

Glioblastoma is the most malignant primary brain tumor with a median survival of 15 months. Temozolomide (TMZ) is the standard of care for these patients. Iron chelators have been shown to have anti-tumor activity; however, deferiprone (DFP), an orally administered iron chelator, has not been previously evaluated in gliomas. In the present study, we found that combination treatment in glioma cells with TMZ and DFP significantly reduced cell viability, produced cell cycle arrest at G2/M phase, and enhanced apoptosis. TMZ and DFP might be a potent new combination treatment for glioblastoma.

Combination treatment of TRAIL, DFMO and radiation for malignant glioma cells.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has shown potent and cancer-selective killing activity and drawn considerable attention as a promising therapy for cancer. Another promising cancer therapy is difluoromethylornithine (DFMO), an inhibitor of ornithine decarboxylase, which is oraly administered and well tolerated. Nevertheless, many types of cancer, including gliomas, have exhibited resistance to TRAIL-induced apoptosis and similarly the potency of DFMO should be enhanced to optimize therapeutic efficacy. In this study we sought to determine whether DFMO, in combination with TRAIL and radiation, could result in an enhanced anti-glioma effect in vitro. We investigated the effect of DFMO, TRAIL and radiation in various combinations on a panel of glioblastoma cell lines (A172, T98G, D54, U251MG). Viability and proliferation of the cells were examined with trypan blue exclusion assay, crystal violet and xCELLigence system. Apoptosis (Annexin-PI), cell cycle and activation of caspase-8 were tested with flow cytometry. BAD protein levels were determined by Western blot analysis. DFMO induced BAD overexpression. Combination treatment with DFMO, TRAIL and radiation significantly reduced cell viability in all cell lines tested. Increased induction of cell death and cell cycle arrest was confirmed with flow cytometry in A172 and D54 cell lines, while enhanced activation of annexin and caspase-8 was revealed in U251MG and T98G cells. The treatment of glioblastoma cell lines with combination of DFMO, TRAIL and radiation showed an enhanced effect. This combination treatment may represent a novel strategy for targeting glioblastoma.

Comparison of (99m)tc-tetrofosmin and (99m)tc-sestamibi uptake in glioma cell lines: the role of p-glycoprotein expression.

(99m)Tc-Tetrofosmin ((99m)Tc-TF) and (99m)Tc-Sestamibi ((99m)Tc-MIBI) are SPECT tracers that have been used for brain tumor imaging. Tumor's multidrug resistance phenotype, namely, P-glycoprotein (p-gp), and the multidrug resistance related proteins (MRPs) expression have been suggested to influence both tracers' uptake. In the present study we set out to compare (99m)Tc-TF and (99m)Tc-MIBI uptake in high-grade glioma cell lines and to investigate the influence of gliomas p-gp expression on both tracers' uptake. We used four glioma cell lines (U251MG, A172, U87MG, and T98G). The expression of p-gp protein was evaluated by flow cytometry. Twenty µCi (7.4·10(5) Bq) of (99m)Tc-TF and (99m)Tc-MIBI were used. The radioactivity in the cellular lysate was measured with a dose calibrator. P-gp was significantly expressed only in the U251MG cell line (P < 0.001). In all gliomas cell lines (U251MG, U87MG, A172, and T98G) the (99m)Tc-TF uptake was significantly higher than (99m)Tc-sestamibi. The U251MG cell line, in which significant p-gp expression was documented, exhibited the strongest uptake difference. (99m)Tc-TF uptake was higher than (99m)Tc-MIBI in all studied high-grade glioma cell lines. Thus, (99m)Tc-TF may be superior to (99m)Tc-MIBI for glioma imaging in vivo.

Combination treatment for glioblastoma cells with tumor necrosis factor-related apoptosis-inducing ligand and oncolytic adenovirus delta-24.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) exhibits cancer-selective killing activity representing a promising anticancer therapeutic strategy. Adenovirus Delta-24 is another interested anticancer agent selectively killing cells with a defective p16/Rb/E2F pathway. However, many types of cancer, including gliomas, could develop resistance to Delta-24 or TRAIL-induced apoptosis. In this study, we investigated whether TRAIL, in combination with adenovirus Delta-24, could result in an enhanced antiglioma effect in vitro in a panel of glioblastoma cell lines (U87MG, U251MG, D54, and T98G). The treatment of glioblastoma cell lines with TRAIL and Delta-24 adenovirus in combination showed markedly enhanced effect, compared to each agent alone.