Abstract 3118: Oncogenesis modeling in malignant pleural mesothelioma

Abstract

Abstract Malignant pleural mesothelioma (MPM) is causally associated with exposure to asbestos and accounts for roughly 75% of mesothelioma cancers. It is an aggressive tumor with a median survival time of approximately 12 months. Treatment options are limited, largely palliative, and still based on cisplatin and pemetrexed, a regimen that remains unchanged since 2003. Despite widespread study, the complexities of MPM biology remain poorly described, especially at the point of tumor initiation where development of novel clinical interventional strategies would be expected to yield the most effect. The extended latency period in humans consisting of decades (over 20-30 years) remains a prohibitive barrier to gain accurate, in vivo insights about MPM oncogenic processes. As such, all in vitro MPM models, which are designed to accelerate tumor development as a practical endpoint of study, to date have not yielded clinically translatable molecular targets. Here, we present a novel in vitro model system for exploring the earliest molecular mechanisms contributing to the development of MPM using normal, human mesothelial cell lines (MeT-5a and LP9-hTERT) engineered to harbor constitutively enhanced NFkB signaling activity. Both 3D-sphere and soft agar assays were used to assess cellular transformation status in these induced cells compared to their wild-type counterparts. Heterotopic xenograft implantation studies were performed in NOD scid-gamma (NSG) immunocompromised mice (sub-cutaneous dorsal flank injection) for tumorigenic potential. In all cases, these induced cells (despite the complete absence of asbestos exposure) exhibited a significant malignant-like phenotype. Tumor growth in mouse xenograft models occurred very rapidly, and was marked by extensive vascular recruitment with invasion into surrounding tissues. In addition, these transformed cells expressed typical mesothelioma markers such as Wilms tumor protein (WT1 gene product) as revealed by immunohistofluorescence. This new MPM model system could represent a powerful construct to explore the early molecular events involved in transformation of normal mesothelial cells leading to malignancy. Citation Format: Nathanael D. Pruett, Anand Singh, Nisan Bhattacharyya, Chuong D. Hoang. Oncogenesis modeling in malignant pleural mesothelioma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3118.