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Malignant mesothelioma (MM) is an aggressive and highly chemo-resistant tumour of the mesothelium. Asbestos is indicated as the environmental factor most commonly associated with mesothelioma. The chemo-resistance is possibly due to impaired apoptotic mechanisms since it is known most chemotherapeutic drugs act via apoptosis. Murine MM cell lines that have been derived from tumours induced by inoculation of crocidolite asbestos into mice provide a suitable model, since both phenotypic and biological properties are closely similar to the human disease. Four murine MM cell lines were used in this study, namely ABl, AB12, AC29 and AC34. The aim of this study was to determine susceptibility of those MM cell lines to induction of apoptosis and the expression of key molecules in those cells. Many apoptosis-related genes are known, expression of some of these genes in four murine MM cell lines were investigated in this study. Gene expression was determined using conventional reverse transcription PCR (RT-PCR) and quantitated using real-time RT-PCR with SYBR-Green I detection on a Rotor-Gene 2000 (Corbett Research, N.S.W., Australia). Gene expression data was normalised against the most stable housekeeping genes as determined by the geNonn software. Susceptibility of the four murine MM cell lines to apoptosis induction was determined using cisplatin or TNF-a or IFN-y at different concentrations and at different times in the case of cisplatin. Apoptosis was assessed by a DNA laddering assay. Conventional RT-PCR results showed that all four murine MM cell lines expressed DR5, Bax, Bcl-xL, FLIP-L, c-Myc and caspase-3. Fas mRNA was detected in all cell lines except AC29. Neither FasL nor Bcl-2 was expressed in the four murine MM cell lines. / Quantitation of gene expression showed that there were significant differences in Fas, DRS, Bax, Bcl-xL, c-Myc, FLIP-L and caspase-3 mRNA levels across the cell lines (P<0.05). Absence of Fas receptor in AC29 may play a role in the immunogenicity of this cell line. DNA laddering results indicated that cisplatin induced apoptosis in a dose- and time- dependent manner in those MM cell lines. Susceptibility as reflected by the minimum apoptosis-inducing dose varied among the cell lines from 1 pdml (AB12) to 10 & n l (AC34). Susceptibility to TNF-a or IFN-y also varied among the cell lines where AB12 was sensitive while AC29 was resistant to those cytokines. The AC29 and AB1 cell lines were used to examine cisplatin or TNF-a induced genes related to apoptosis, expression of Fas, caspase-3, Bax and Bcl-xL mRNA was determined using real-time RT-PCR after 6 and 24 hours induction with cisplatin or TNF-a. The results demonstrated that caspase-3 and Bax were up-regulated whereas Bcl-xL was down-regulated in AC29 after 6 hours treatment with cisplatin. Although only Bcl-xL was down-regulated in ABl after 6 hours treatment with cisplatin, the down regulation was more pronounced than in AC29. TNF-a induction of gene expression showed that Bcl-xl decreased and Fas was up-regulated significantly in AB1 after 6 hours whereas only Bcl-xL was down-regulated in AC29 after 6 hours and continued to decrease until 24 hours. The differences in gene expression changes were noticed not only between cell lines but also between two inducer agents. There were several significant results of this study. Firstly, gene expression in murine MM was seen to parallel those that have previously been described for the human disease. / Therefore murine MM is likely to be a useful in in vivo model for future studies targeting apoptotic molecules. Secondly, a number of genes were not previously examined in MM were characterized in the murine model. Finally, differences in basal and induced gene expression between cell lines and inducing agents were characterized which should be followed in further studies at the protein level (eg caspase-3 activity).

Diss. (sammanfattning) Umeå : Univ., 2007. / Härtill 4 uppsatser.

Yes / Background The HOX genes are a family of homeodomain-containing transcription factors that determine cellular identity during development and which are dys-regulated in some cancers. In this study we examined the expression and oncogenic function of HOX genes in mesothelioma, a cancer arising from the pleura or peritoneum which is associated with exposure to asbestos. Methods We tested the sensitivity of the mesothelioma-derived lines MSTO-211H, NCI-H28, NCI-H2052, and NCI-H226 to HXR9, a peptide antagonist of HOX protein binding to its PBX co-factor. Apoptosis was measured using a FACS-based assay with Annexin, and HOX gene expression profiles were established using RT-QPCR on RNA extracted from cell lines and primary mesotheliomas. The in vivo efficacy of HXR9 was tested in a mouse MSTO-211H flank tumor xenograft model. Results We show that HOX genes are significantly dysregulated in malignant mesothelioma. Targeting HOX genes with HXR9 caused apoptotic cell death in all of the mesothelioma-derived cell lines, and prevented the growth of mesothelioma tumors in a mouse xenograft model. Furthermore, the sensitivity of these lines to HXR9 correlated with the relative expression of HOX genes that have either an oncogenic or tumor suppressive function in cancer. The analysis of HOX expression in primary mesothelioma tumors indicated that these cells could also be sensitive to the disruption of HOX activity by HXR9, and that the expression of HOXB4 is strongly associated with overall survival. Conclusion HOX genes are a potential therapeutic target in mesothelioma, and HOXB4 expression correlates with overall survival. / The authors gratefully acknowledge the support of the British Lung Foundation, grant number ICAPPG10-1. KJH acknowledges support from the ICR/RM NIHR Biomedical Research Centre.

Malignant mesothelioma (MM) is an aggressive malignancy of the pleural and peritoneal surfaces. Australia has the highest reported national incidence of mesothelioma in the world, and rates are increasing (Leigh et al., 2002). The clinical outcome for patients with this disease is extremely poor, with median survival of 9 to 12 months (Rizzo et al., 2001; Carbone et al., 2002). The latest developments in chemotherapy, radiotherapy and radical surgery have done little to improve the overall survival rate (Kindler 2000; Zellos et al., 2002). New approaches to therapy are thus required (Nowak et al., 2002). Cancer therapy using conditionally replicative adenoviruses (CRAds) and attenuated measles virus (vaccine strain MV-Edm) are novel and promising approaches to cancer treatment. CRAds strategy relies on selective viral replication in tumour cells but not normal cells. Major efforts have been directed toward achieving selective replication by the deletion of viral functions dispensable in tumour cells or by the regulation of viral genes with tumour-specific promoters (Alemany et al., 2000). However, the major clinical limitation of viral therapy has been lack of efficacy rather than safety concerns. In this study, I constructed CRAds in which tumour-specific promoter for Flt-1 (vascular endothelial growth factor receptor) control the essential E1 gene expression, and evaluated the cell-killing efficacy and specificity of CRAds driven by VEGF and Flt-1 promoters in the number of established mesothelioma cell lines and actual primary tumour cells from patients. CRAds with either VEGF or flt-1 promoters showed a strong killeg effect on mesothelioma cells. Co-delivery of CRAds with MMP-9 (matrix metalloproteinase-9) was assessed to determine whether therapeutic efficacy could be improved by reducing tumourassociated fibrosis thereby enhancing viral spread through a tumour mass. Combined therapy did result in greater suppression of tumour growth in vivo. I also identified an immuno-competent murine model of mesothelioma that was permissive for adenoviral replication. Combined viral therapy with immunotherapy (FGK45, an anti-CD40 antibody) in this model resulted in greater effect than Adwt or FGK45 alone and in greatest survival. I evaluated the capacity of MV-Edm to infect human mesothelioma cells to form syncytia, and lead to apoptosis and cell death. I also assessed the mode of death by analysis of markers of apoptosis including caspase-3. In vivo study showed that MVEdm- GFP transduction could be detected in human xenografts in immune deficient mice. Further studies to evaluate the mechanisms and efficacy of anti-tumour immune stimulation induced by tumour cell killing with CRAds and MV-Edm will be discussed in this study. MV-Edm has good killing effect on mesothelioma cells in vitro. In summary the work presented herein provide new insights into stratgies to improve viral therapies for mesothelioma. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1342596 / Thesis (Ph.D.) - University of Adelaide, School of Medicine, 2008

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2010.

Introduction Pleural mesothelioma constitutes about 80% of all mesotheliomas. The peak incidence of malignant mesothelioma estimated using the cancer registries was in early 1990 to 2000 in the United States. The disease is primarily associated with asbestos exposure. The latency period between asbestos exposure and the development of malignant pleural mesothelioma (MPM) can range anywhere from 15 to 60 years. Asbestos exposure was peaked during the industrial revolution and World War II due to military and shipyard exposures. It is often difficult for the pathologist to distinguish different histological subtypes; due to the disease's rarity and the inadequate tissue sample obtained. There is no available data on the difference in epidemiology of different subtypes of MPM. Surveillance Epidemiology and End Results (SEER), cancer incidence data include population-based registries covering approximately 34.6% of the U.S. population. Here in our study, we analyze malignant pleural mesothelioma epidemiology in the United States, emphasizing different histological subtypes. Methods SEER data from 2000 to 2016 was used in our study. The primary site of cancer is selected as pleura, and malignant behavior only is selected as the filter. Data were analyzed using the SEER stat program. Overall epidemiology of MPM and epidemiology of epithelioid, fibrous, and biphasic histological subtypes were analyzed separately. We used annual percentage change (APC) to evaluate the trend in the epidemiology of MPM. Results summary A total of 11,857 cases of MPM were included in the primary cohort from the SEER 18 registry from 2000 to 2016. The total prevalence of MPM was highest in 2009 and was lowest in 2016. The APC in MPM incidence during this period is -2.0. After removing 5,989 cases with non-specified histology during the same period, the APC for each histological type is -0.7 for fibrous type, 1.8 for epithelioid type, and 2.9 for biphasic type. Out of 17 regional registries included in the study, the greatest statistically significant change in APC was seen in the Hawaiian registry -4.1. In contrast, the lowest statistically significant difference was seen in Seattle (Puget Sound) registry -1.7. The APC in the incidence of MPM among males during the study period was -2.4 while that of females was -0.9. The Iowa registry showed a statistically significant increase in APC of the epithelioid malignant mesothelioma with a statistically insignificant reduction in the overall MPM APC. Conclusion The overall incidence of MPM in the United States is declining, while the data showed an increase in the incidence of epithelioid and biphasic histological subtypes. The authors believe that these conflicting results can be attributed to improved histological diagnosis and improved biopsy techniques.

Malignant mesothelioma (MM) is a locally invasive and highly aggressive cancer arising on the mesothelial surface of organ cavities (mainly pleural) as a direct result of asbestos exposure. The latency period of MM is long (20-50yrs) after initial asbestos exposure, and the prognostic outcomes are dismal with median life expectancy of 6-12 months post-diagnosis. There are no useful biomarkers for early MM diagnosis, no successful therapeutic interventions. These vast voids of knowledge led to our hypotheses that secreted vesicles, termed exosomes, play an important role in MM development and tumorigenic properties. Exosomes are nano-sized particles secreted from all cell types and carry biologically active cargo in the form of proteins, RNA, and lipids that can potently act as intercellular messengers in both healthy settings and disease states. We are the first to have conducted studies implicating the roles of exosomes in MM pathogenesis. Firstly, we analyzed the proteomic signature of exosomes from asbestos exposure models, in vitro and in vivo. Our in vitro data demonstrated that asbestos exposed lung epithelial cells and macrophages secrete exosomes with differentially abundant proteins compared to non-exposed controls and some of these proteins are relevant to asbestos exposure toxicology and MM development. Additionally, the exosomes from asbestos exposed cells significantly modulated the gene expression of target mesothelial cells in a way that reflected epithelial to mesenchymal transition and other tumorigenic properties. The in vivo mouse studies illustrated that mouse serum exosomes house differentially abundant proteins after asbestos exposure and this is measurable at an organism wide scale. Secondly, we assayed the miRNA composition of MM tumor exosomes compared to healthy mesothelial cell exosomes and found signature differences in miRNA abundances, particularly that MM tumor cells had significantly higher amounts of tumor suppressor miRNA, particularly miR-16-5p, in their exosomes. This led to the hypothesis that MM tumor cells preferentially secrete tumor suppressor miRNAs via exosomes to rid themselves of the anti-tumor effects. We employed exosomes secretion inhibitors and exosome force-feeding to demonstrate that MM cells do in fact secrete miR-16-5p (along with other tumor suppressor miRNAs) through exosomes and that this property can be targeted as a potentially novel therapeutic advance. Furthermore, we identified a mechanism of miR-16-5p loading into exosomes by the RNA binding protein HuR, and this mechanism is interestingly regulated by miR-16-5p itself in a negative feedback loop. Our studies thus far provide intriguing evidence on the role of exosomes in asbestos exposure and MM biology. We demonstrated the potential for exosomes as protein biomarkers in asbestos exposure and conduits of tumorigenic information to mesothelial cells. In addition, we incriminate exosomes as vehicles of tumor suppressor removal from MM tumor cells and we can target this as a potential n MM therapy.

Malignant mesothelioma (MM) is an aggressive tumour, which is highly associated with previous asbestos exposure and is resistant to most conventional anticancer therapies. Previous studies have used a mouse model of to 01 p effective approaches to induction of anti-tumour immunity using modification of tumour cells by the introduction of genetic constructs expressing genes such as that for B7-1 so that tumour growth can be inhibited in vivo. Transfectant clones, AC29 B7-7 and AC29 B7-6, which showed equal levels of expression of B7-1 but were markedly different in tumorigenicity were assessed using suppression subtractive hybridization (SSH) in order to isolate transcripts which may have been differentially expressed in the two clones. SSH allowed isolation of a number of cDNAs which were apparently differentially expressed in the cell lines. These required characterisation in order to determine their possible relevance to tumorigenicity. Two cDNAs designated as 7-7-76 and 7-7-43 had been isolated previously and the aim of this project was to characterise these cDNAs by sequencing, searching for their homology relationships and investigating gene expression profiles. Preliminary searches revealed that clone 7-7-43 had homology to cyclin-dependent kinase regulatory subunit 1 which plays a role in the cell cycle. On the other hand, clone 77-76 showed only homology to an EST of hypertension related protein and therefore, further investigation was required to obtain the identity of clone 7-7-76. The first part of this project was to in investigate and evaluate gene expression on clone 7-7-43, using both relative RT-PCR and Northern blotting.' In the second part of this project, a more intense study of clone 7-7-76 was conducted. Clone 7-7-76 was investigated for its homology relationships and its gene expression profile. / Results obtained from relative RT-PCR suggested no difference in the expression of the either eDNA clone (7-7-43 and 7-7-76) between the MM clones AC29 B7-6 and AC29 B7-7, the cells used to derive these clones by SSH. Therefore, it was concluded that neither clone 7-7-43 nor 7-7-76 was differentially expressed in MM cells of differing immuno enicit RACE was employed in order to derive a longer sequence of clone 7-7-76 and the newly derived sequence of 7-7-76 was again used to search for homologies using a wider range of sequences for human and other species. These investigations on clone 7-7-76 showed it to correspond to the sequence of human mitofusin 2 which is involved in determining mitochondrial morphology The results determined in this project suggest that clones 7-7-43 and 7-7-76 are not differentially expressed in the range of MM cell lines tested. The data have however highlighted the potential of the SSH technique to easily derive cDNA clones worthy of investigation, but underline the possibility of false positive clones being isolated. The need for an efficient, accurate screening procedure such as real-time PCR is acknowledged.

Le mésothéliome pleural est un cancer de la plèvre provoqué principalement par linhalation de fibres damiante. Nous avons émis lhypothèse que la dérégulation de lexpression génique est un paramètre important du développement de cette maladie. Or, les histones désacétylases (HDACs) peuvent jouer le rôle de répresseur transcriptionnel en modifiant la conformation de la chromatine. Dans ce contexte, nous avons étudié lactivité anticancéreuse du valproate, un inhibiteur dHDAC, en combinaison avec différents types de traitements utilisés en chimiothérapie. Nous avons démontré leffet synergique entre la chimiothérapie et le valproate dans des lignées cellulaires et dans des biopsies isolées à partir de patients. Nous avons étudié les processus impliqués dans lapoptose et révélé limplication des caspases, des espèces oxygéno-réactives et le rôle important de la protéine Bid. Nous avons ensuite réalisé une étude transcriptomique par microdamiers dans le but de mieux caractériser les mécanismes impliqués. Enfin, nous avons démontré lefficacité du valproate dans un modèle préclinique murin. Ces recherches ont permis la mise en place dun essai clinique de deuxième ligne sur des patients réfractaires à une première chimiothérapie.