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L. Mutti
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P1.02 - Poster Session 1 - Novel Cancer Genes and Pathways (ID 144)
- Event: WCLC 2013
- Type: Poster Session
- Track: Biology
- Presentations: 1
- Moderators:
- Coordinates: 10/28/2013, 09:30 - 16:30, Exhibit Hall, Ground Level
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P1.02-013 - SDHB is overexpressed and may be a candidate target for therapeutic intervention in Malignant Pleural Mesothelioma (ID 3287)
09:30 - 09:30 | Author(s): L. Mutti
- Abstract
Background
Malignant pleural mesothelioma (MPM) is a rare aggressive cancer of the pleura. Asbestos exposure (through inhalation) is the most well established risk factor for mesothelioma. The current standard of care for patients suffering from MPM is a combination of cisplatin and pemetrexed (or alternatively cisplatin and raltitrexed). Most patients however, die within 24 months of diagnosis. New therapies are therefore urgently required for this disease. The Succinate Dehydrogenase Complex, Subunit B, IronSulfur Protein (SDHB), is a subunit of the Succinate dehydrogenase or succinate-coenzyme Q reductase (SQR) or respiratory Complex II, and has recently been identified by us as an important element in MPM.Methods
A panel of MPM cell lines inluding the normal pleural cells LP9 & Met5A were screened for expression of SDHB by RT-PCR. Levels were subsequently examined in a cohort of snap-frozen patient samples isolated at surgery comprising benign, epithelial, biphasic, and sarcomatoid histologies by RT-PCR and western blot. Finally the expression of SDHB in a large cohort of MPM specimens with clinical data was asessed by IHC.Results
Expression of SDHB occurs in all cell lines. Significantly higher expression of SDHB is observed in the malignant tumour material versus benign pleura. There was a trend towards better survival for patients expressing higher levels of SDHB, but this was not statistically significant.Conclusion
SDHB, a key member of oxidative energy metabolism is significantly altered in MPM. This may have important future implications for the management of MPM.
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P1.06 - Poster Session 1 - Prognostic and Predictive Biomarkers (ID 161)
- Event: WCLC 2013
- Type: Poster Session
- Track: Biology
- Presentations: 1
- Moderators:
- Coordinates: 10/28/2013, 09:30 - 16:30, Exhibit Hall, Ground Level
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P1.06-055 - The RON (MST1R)/MSP pathway is a potential therapeutic target in malignant plural mesothelioma (ID 3250)
09:30 - 09:30 | Author(s): L. Mutti
- Abstract
Background
Malignant pleural mesothelioma (MPM) is an aggressive inflammatory cancer. Treatment options are limited and drug resistance is common. Thus, there is a need to identify novel therapeutic targets in this disease in order to improve treatment options and survival times. Macrophage stimulating protein (MSP) is the only ligand recognised to bind to the RON receptor (MST1R). RON is a member of the MET proto-oncogene family. The MSP-RON signalling pathway has been implicated in a variety of cellular functions such as macrophage morphogenesis and phagocytosis. De-regulation of this pathway has been linked to tumour progression and metastasis in a number of cancers. We have previously identified RON as frequently activated in MPM and high positivity for RON by IHC was an independent predictor of favourable prognosis.Methods
A panel of mesothelioma cell lines were screened for the expression of MSP and RON at the mRNA (RT-PCR) and protein (Western blot) level. The effect of MSP, IMC-RON8 (a humanised IgG1 monoclonal antibody), LCRF004 (a small molecule inhibitor) and NRWHE (a small peptide) was examined in the H226 cell line using proliferation (BrdU ELISA), apoptosis (Multi-parameter apoptosis assay) and migration assays (xCELLigence). A phospho-kinase proteome profiler array was utilised to detect the downstream signalling pathways activated upon MSP stimulation. The expression of MSP and the macrophage marker, CD-68, was examined by IHC using MPM TMAs. Studies are ongoing to determine the effect of the LCRF004 compound in vivo using a xenograft murine model with the H226 cells.Results
The mRNA and protein levels of RON and MSP were differentially expressed in a panel of MPM cell lines. Treatment with LCRF004 resulted in significantly decreased proliferation and increased apoptosis in the H226 cells. MSP was unable to rescue the cells from the effects of LCRF004. NRWHE and RON8 had little effect on either proliferation or apoptosis. All of the compounds examined inhibited the migration capacity of the H226 cells. The combination of LCRF004 and MSP produced a synergistic effect, showing greater inhibition of migration than either compound alone. However, MSP treatment resulted in the up-regulation of a number of phosphor-kinases including Akt, ERK and the Src family. Currently, a number of proteins identified in the array studies are undergoing validation. Results of an in vivo H226 murine model using the LCRF004 compound will be presented at the meeting.Conclusion
From previous work performed in this laboratory, we have determined that high expression of RON in MPM is an independent predictor of favourable prognosis. IHC was performed on a TMA of MPM patient samples and high expression levels of MSP correlated with better survival. There was no association between CD68 staining and MSP, nor correlation of CD68 expression with survival. Targeting the RTK domain of the RON receptor with a small molecule inhibitor is an effective interventional strategy in MPM. The seemingly counter intuitive results obtained from the MPM TMA studies and the in vitro experimental data, may be RON isoform dependant. Additional studies are ongoing to further delineate the RON-MSP axis in MPM.
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P3.01 - Poster Session 3 - Cancer Biology (ID 147)
- Event: WCLC 2013
- Type: Poster Session
- Track: Biology
- Presentations: 1
- Moderators:
- Coordinates: 10/30/2013, 09:30 - 16:30, Exhibit Hall, Ground Level
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P3.01-014 - Expression and post-translational modifications of AKT isoforms in Malignant pleural Mesothelioma cells (ID 3252)
09:30 - 09:30 | Author(s): L. Mutti
- Abstract
Background
Background: The PI3K/AKT signaling pathway is aberrantly active and has an important biologic impact in malignant pleural mesothelioma (MMe) cell cycle progression and chemo-resistance. Akt consists of three isoforms, Akt1, Akt2, and Akt3. Despite the growing amount of research demonstrating the existence of isoform-specific regulation, many papers still draw generalized conclusions about AKT without focusing on functional specificity of each isoforms. Recent data have clearly demonstrated a role of SIRT1 in the modulation of AKT1 activation and a role of PARP1 as a gatekeeper for SIRT1 activity by limiting NAD+ availability.Methods
Methods: We explored the expression of AKT isoforms in MMe in vivo and in vitro and the balancing between their acetylation and phosphorylation status in human MMe derived cell lines in vitro.Results
Results: We firstly described that MMe tumors in vivo and MMe derived cell lines express both AKT1 and AKT3 isoforms but not AKT2, and their expression results significantly increased in the biphasic histotype. Furthermore, we demonstrated an inverse correlation between AKTs acetylation and phosphorylation modulated by PARP1/SIRT1 activation status. By immunoprecipitation experiments, we evidenced that in basal conditions AKT1 is in part acetylated and in part phosphorylated and became highly phosphorylated and completely de-acetylated upon PARP1 inhibition. Interestingly, AKT1 activation, related to PARP1 inhibition, is unable to modulate pro-survival signals, because the downstream pathway is interrupted at the level of its effector mTOR. Conversely, SIRT1 inhibition or silencing result in a more evident AKT1 and its interactors acetylation.Conclusion
Conclusions: In conclusion, our results clearly show how both PARP1 and SIRT1 affect critical cellular pathways involved in MMe progression and offer a model of a regulatory inter-relationship between these proteins. These data could be helpful for designing new effective therapeutic strategies.
