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F. Rea
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P2.08 - Poster Session/ Thymoma, Mesothelioma and Other Thoracic Malignancies (ID 225)
- Event: WCLC 2015
- Type: Poster
- Track: Thymoma, Mesothelioma and Other Thoracic Malignancies
- Presentations: 1
- Moderators:
- Coordinates: 9/08/2015, 09:30 - 17:00, Exhibit Hall (Hall B+C)
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P2.08-003 - MDM2 Inhibitor plus rhAPO2L/TRAIL: A Promising Strategy for Malignant Pleural Mesothelioma Treatment (ID 2417)
09:30 - 09:30 | Author(s): F. Rea
- Abstract
Background:
Malignant Pleural Mesothelioma (MPM) is an aggressive tumor characterized by chemoresistance. Most MPM tumor specimens have wild type p53 but show a deletion of INK4A/ARF locus (70-80%) which contains p14/ARF gene. The p14 lack increases MDM2 activity and subsequently down-regulates p53. The role of MDM2 is not only related to p53 control but it is also involved in regulation of cell proliferation, apoptosis and angiogenesis in p53 independent manner. Tumor necrosis factor (TNF)-Related Apoptosis-Inducing Ligand (Apo2L/TRAIL) is a promising agent for antitumor treatment because its ability to selectively kill cancer cells through the extrinsic apoptotic pathway. The aim of our study is to investigate, the anticancer effect of the MDM2 inhibitor, Nutlin 3a, in association with rhAPO2L/TRAIL in MPM in vitro and in vivo.
Methods:
In vitro apoptosis assay was performed using PI staining, positive cells were detected by flow cytometry. Cycle analysis was performed by PI staining and flow cytometry detection, DNA content was analyzed by MODFIT software. p53, p21 and survivin protein expression levels were detected by western blot analysis. TRAIL receptors levels were assessed by flow cytometry analysis. mRNA expression levels were evaluated by real-time PCR. In vivo experiments were performed in 32 SCID male mice, intraperitoneally injected with sarcomatoid MPM cells trasduced with lentiviral Luciferase vector and treated with Nutlin and/or rhAPO2L/TRAIL.
Results:
Nutlin 3a treatment provoked p21 induction and cell cycle arrest in p53 wild type cells (M14K epithelioid, MSTO-211H biphasic and ZL34 sarcomatoid) but had no effect in p53 mutated cells (ZL55 epithelioid). Interesting, apoptosis assay showed a synergistic cell death induction of Nutlin3a plus rhAPO2L/TRAIL in both p53 wild type and p53 mutated MPM cells with a greater effect in ZL34 cell lines that expressed higher mRNA and protein levels of MDM2. Nutlin 3a increased the expression of DR4/DR5 TRAIL death receptors and inhibition of survivin only in p53 wild type cells. As a consequence, western blot analysis of Caspase 8 activation showed that the MDM2 inhibitor induced an increase of extrinsic apoptosis signal only when p53 was functional. Finally, antitumor activity tested in ZL34 in vivo mouse model showed a strong inhibition of tumor growth in mice treated with Nutlin 3a plus Apo2L/TRAIL compared to Nutlin 3a or Apo2L/TRAIL used as single agents.
Conclusion:
The results demonstrate that the combination of Nutlin 3a plus Apo2L/TRAIL may be a promising strategy for MPM treatment independently to p53 status. Further esperiments are needed in order to clarify the role of p53 status as selection criterium for treatment and to explore p53-independent MDM2 functions.
