Human Malignant Pleural Mesothelioma Cell Research Articles

218 Effects of insulin-like growth factor binding protein-3 on human malignant pleural mesothelioma cell growth and apoptosis

218 Effects of insulin-like growth factor binding protein-3 on human malignant pleural mesothelioma cell growth and apoptosis

Restored Expression of the MYO18B Gene Suppresses Orthotopic Growth and the Production of Bloody Pleural Effusion by Human Malignant Pleural Mesothelioma Cells in SCID Mice

Malignant pleural mesothelioma (MPM) is closely related to exposure to asbestos, and a rapid increase in the number of MPM patients is therefore estimated to occur from 2010 to 2040 in Japan. Because MPM is refractory to conventional chemotherapy and radiotherapy, the prognosis of MPM patients is extremely poor. MYO18B, a novel member of the myosin family, is a tumor suppressor gene isolated from a homozygously deleted region at 22q12.1 in a lung cancer cell line. The inactivation of the MYO18B gene plays an important role in several malignant diseases. However, the role of MYO18B in the progression of MPM is still unknown. Six different human MPM cell lines were used in this study. Western blot revealed that none of the cell lines expressed a detectable level of MYO18B protein. One of the MPM cell lines, EHMES-10, was transfected with the MYO18B gene. We found that a restored expression of the MYO18B protein in EHMES-10 cells resulted in the inhibition of their anchorage-independent growth and motility in vitro. In addition, it also inhibited their ectopic (subcutaneous space) and orthotopic (thoracic cavity) growth in SCID mice, in association with an increased degree of cell apoptosis. Furthermore, it also suppressed the production of bloody pleural effusion after orthotopic injection. These findings suggest that the restored expression of MYO18B may be a useful therapeutic strategy for the treatment of locally advanced MPM in humans.

Novel orthotopic implantation model of human malignant pleural mesothelioma (EHMES‐10 cells) highly expressing vascular endothelial growth factor and its receptor

Malignant pleural mesothelioma (MPM) is closely related to exposure to asbestos, and a rapid increase in the number of MPM patients in Japan is estimated in the years 2010-2050. The purpose of the present study was to establish a clinically relevant animal model that shows human patient-like progression of MPM. Here, we demonstrate that a human MPM cell line (EHMES-10) inoculated orthotopically (thoracic cavity) into severe combined immunodeficiency (SCID) mice produces highly vascularized thoracic tumors with pleural dissemination and bloody pleural effusions by 5 weeks, suggesting a patient-like progression of this cell line after orthotopic inoculation. EHMES-10 cells overexpressed vascular endothelial growth factor (VEGF), a molecule responsible for malignant effusions, and its receptor. Treatment with cisplatin, but not gemcitabine, significantly inhibited the production of pleural effusions, but it was not effective for thoracic tumors, consistent with chemotherapy refractory characteristics of MPM in patients. Our patient-like orthotopic model using EHMES-10 cells overexpressing VEGF and its receptor may be useful for examining the molecular pathogenesis of MPM and may contribute to the development of novel treatment strategies for MPM.

Cisplatin-induced GADD34 upregulation potentiates oncolytic viral therapy in the treatment of malignant pleural mesothelioma

Background: NV1066, a replication-competent oncolytic herpes simplex virus type 1 (HSV-1) attenuated by a deletion in the gene _134.5, preferentially replicates in and kills malignant cells. _134.5 encodes ICP34.5, a viral protein essential for productive replication, which has homology with mammalian stress response induced GADD34 (Growth Arrest and DNA Damage-Inducible Protein). We hypothesized that cisplatin upregulates GADD34 expression, which enhances NV1066 replication and oncolysis.Methods: Ten human malignant pleural mesothelioma (MPM) cell lines were infected with NV1066 at multiplicities of infection (MOI; ratio of viral particles per tumor cell) 0.005 to 0.8 in vitro, with and without cisplatin (1 to 4 µM). In the MPM cell line VAMT, viral replication was determined by plaque assay, cell kill by lactate dehydrogenase assay, and GADD34 induction by quantitative RT-PCR and Western blot. Synergistic efficacy was confirmed by the isobologram and combination index methods of Chou-Talalay. GADD34 upregulation by cisplatin was inhibited with GADD34 siRNA to further confirm the synergistic efficacy dependence with GADD34.Results: Combination therapy with NV1066 and cisplatin showed strong synergism in epithelioid (H-2452, H-Meso), sarcomatoid (H-2373, H-28), and biphasic (JMN, Meso-9, MSTO-211H) MPM cell lines, and an additive effect in others. In VAMT cells combination therapy enhanced viral replication 4 to11-fold (p < 0.01) and cell kill 2 to 3-fold (p < 0.01). Significant dose reductions for both agents (2 to 600-fold) were achieved over a wide range of therapeutic-effect levels (LD50 – LD99) without compromising cell kill. Synergistic cytotoxicity correlated with GADD34 upregulation (2 to 4-fold, p < 0.01) and was eliminated following transfection with GADD34 siRNA.Conclusion: Cisplatin-induced GADD34 expression selectively enhanced the cytotoxicity of the _134.5-deficient oncolytic virus, NV1066. This provides a cellular basis for combination therapy with cisplatin and NV1066 to treat MPM and achieve synergistic efficacy, while minimizing dosage and toxicity.

Antisense oligonucleotides directed at the bcl-xl gene product augment chemotherapy response in mesothelioma

Abstract Objective: Malignant pleural mesothelioma (MPM) is resistant to both conventional chemotherapy and apoptosis. The bcl-2 family proteins are major determinants of apoptotic homeostasis. MPM lines and tumors routinely overexpress the anti-apoptotic protein BCL-XL. We have previously shown that antisense inhibition of BCL-XL in MPM cells leads to apoptosis. We sought to determine whether antisense oligonucleotides directed at the bcl-xl gene product would augment response to a conventional chemotherapeutic agent in human mesothelioma cell lines. Methods: The human MPM cell lines REN and I-45 were exposed to two bcl-xl antisense oligonucleotides (15999, 16009) and one sense oligonucleotide (113529) construct at varying doses, followed by IC50 cisplatin. Cellular viability was assessed by a calorimetric assay, and apoptosis was evaluated by Hoechst staining, Annexin V staining, and sub-G1 fluorescence-activated cell sorter analysis. Western blot analysis of BCL-2 family proteins was performed following single agent and combined treatment. Isobologram mathematical analysis was used to determine whether or not combination therapies were additive or synergistic. Results: Cell viability was most affected with the 15999 antisense oligonucleotides plus IC50 cisplatin combination (70% of I-45 and 90% of REN cells killed), and apoptosis was markedly increased with this combination by all measures. Western blot demonstrated 15999 antisense oligonucleotides construct down-regulation of BCL-XL, but no further effect on expression of BCL-2 proteins with cisplatin. Isobologram analysis demonstrated 15999 + cisplatin synergistic effect. Conclusions: Exposure of human MPM cells to bcl-xl antisense oligonucleotides sensitizes human mesothelioma cells to the conventional chemotherapeutic agent cisplatin. Similar approaches using a combination of molecular and conventional treatment may have clinical utility for this tumor.

Enhanced effectiveness of last generation antiblastic compounds vs. cisplatin on malignant pleural mesothelioma cell lines

The purpose of this study was to examine the antiproliferative potentialities of a pool of new generation compounds (Paclitaxel, Docetaxel, Gemcitabine, Topotecan, SN-38) together with fenretinide, a synthetic derivative of retinoic acid, in comparison with the current first choice treatment cisplatin molecule, on a pool of human malignant pleural mesothelioma cell lines derived from either bioptic and pleural effusions samples. To evaluate the chemosensitivity features of malignant mesothelioma cells in vitro, we resorted to a rapid and reproducible colorimetric assay, a useful widely recognized tool for preclinical drug screening. In addition, by DNA content analysis and cellular morphologic assessment, we focused on the apoptosis as a potential mechanism of drug activity. The main results clearly indicate that, in all the models of malignant mesothelioma we handled in vitro, each tested antineoplastic agent is more powerful than cisplatin in inhibiting cell proliferation. Moreover, on experimental evidences basis, we can assume that the cytotoxic activity of tested compounds could be related, at least partially, to the drug-induced programmed cell death. This experimental study gives substance to the expected pharmacologic worth of the second generation antineoplastic drugs even if, in order to afford the most satisfactory biopharmacological approach, allowing to bypass the refractoriness to chemotherapy of this highly lethal tumour, further investigations at preclinical level are required.

Adenoviral Transfer of mda-7 Leads to BAX Up-regulation and Apoptosis in Mesothelioma Cells, and is Abrogated by Over-expression of BCL-XL

Malignant pleural mesothelioma (MPM) is unresponsive to conventional therapies. Forced expression of the novel tumor suppressor mda-7 gene in other cell types has resulted in decreased growth and apoptosis. We evaluated cell growth, apoptosis and tumor suppressor characteristics following forced expression of this gene in mesothelioma cell lines. MDA-7 expression in human MPM cells at baseline, following pharmacologic differentiation and viral mda-7 transduction (Ad-mda7) were evaluated with Western blot. Cell viability was evaluated with a colorimetric (XTT) assay, and apoptosis with subG1 FACS and Hoescht. Caspase-3 expression was evaluated by functional assay. These parameters were also evaluated in a stable bcl-xl hyper-expressing MPM cell line. Bax mRNA levels were evaluated with real-time PCR. No baseline or differentiated MPM MDA7 expression was found, but was noted following Ad-mda7 exposure. More than 50% of MPM cells were killed at 5 days following Ad-mda7 exposure (p < 0.001). Apoptosis was accompanied by caspase-3 cleavage and increased BAX expression at both the protein (translational) and mRNA (transcriptional) level. These findings were reduced in a bcl-xl hyper-expressing cell line (P < 0.01). Although mda-7 does not appear to be a MPM suppressor gene, adenoviral-mediated expression in cell lines induces apoptotic cellular death related to BAX upregulation and caspase cleavage. This is supported by abrogation of effect in a bcl-xl hyper-expressing cell line.

Hyperthermia and mafosfamide in a human-derived malignant pleural mesothelioma cell line.

Diffuse malignant pleural mesothelioma is the most common primary pleural malignancy. At the beginning of the last century, this tumor was of minor incidence. Meanwhile, the use of asbestos has led to and is still leading to a rise in pleural mesothelioma incidence. There is no standard therapy for this highly aggressive disease and the development of new therapeutic strategies is imperative. We, therefore, investigated the morphological and pharmakokinetic effects of a combined thermochemotherapy consisting of the administration of different dosages of mafosfamide with and without the application of a 1-h hyperthermia at 41.7 degrees C on the human biphasic malignant pleural mesothelioma cell line MSTO-211H. After therapy, cells were prepared for light and electron microscopy. BrdU-incorporation for the S-phase fraction, TUNEL-labeling for detection of apoptosis, and quantitative assessments using the MTT assay were performed. Our results demonstrate that the combination of mafosfamide with hyperthermia leads to qualitatively and quantitatively enhanced cellular damage compared to monotherapy. During combined thermochemotherapy, cell damage and death is already induced at lower mafosfamide concentrations than without hyperthermia which suggests an additive effect from hyperthermia to the action of the alkylating drug mafosfamide. Cell death thereby mostly occurs as necrotic cell death rather than as apoptosis, although in a combined thermochemotherapy apoptosis is induced temperature-dependently, when comparing temperatures from 37 degrees C to 43 degrees C. We suggest that the effect of substances such as ifosfamide and cyclophosfamide which are in clinical use, might be enhanced by the combination of local or regional hyperthermia in order to improve the therapeutical index of these substances in the treatment of pleural mesothelioma.