Poster Presentation 30th Lorne Cancer Conference 2018

The expression of miR-143, miR-214 and miR-223 in malignant pleural mesothelioma xenograft tumours is primarily from stromal cells. (#256)

Kadir H Sarun 1 , Yuen Y Cheng 1 2 , Michaela Kirschner 3 , Nico Van Zandwijk 2 , Ruby CY Lin 4 , Glen Reid 1 2
  1. Asbestos Diseases Research Institute, Concord, NSW, Australia
  2. Sydney Medical School, The University of Sydney, Sydney, NSW, Australia
  3. Division of Thoracic Surgery, University Hospital Zurich, Zurich, Switzerland
  4. School of Medical Sciences, University of New South Wales, Sydney, NSW, Australia

Malignant pleural mesothelioma (MPM) is an aggressive cancer caused by asbestos exposure with limited therapeutic options. Dysregulated microRNAs play an important role in MPM biology and candidate microRNAs have been investigated as diagnostic and prognostic biomarkers or as a potential treatment targets. To better understand changes in microRNA expression in the MPM tumour microenvironment, the relative contributions of tumour and stromal cells to microRNA expression in tumour xenografts, and the functional activity of microRNA mimics.

Human MPM cell line (MSTO-H211 and H226)-derived xenograft mouse model systems were established. MicroRNA profiles of xenografts were compared against profiles of their corresponding in vitro cultured cells to determine candidates. RT-qPCR using TaqMan MicroRNA assays were used to validate expression levels of miR-143-3p, miR-214-3p and miR-223-3p. Species-specific pri-miR transcripts were analysed to distinguish microRNA contribution from mouse stroma vs human MPM tumour cells within the same xenograft. Cultured tumour cells were transfected with microRNA mimics to investigate the growth effects of microRNAs suspected of stromal origin.

Using RT-qPCR, significantly increased levels of miR-143-3p (197-fold, P<0.04), miR-214-3p (4065-fold, P<0.01) and miR-223-3p (17688-fold, P<0.03) were detected in human MPM xenografts vs the same cell lines grown in tissue culture. Species-specific ddPCR analysis depicted dominant mouse stromal expression of pri-miR-143, pri-miR-214 and pri-miR-223. Overexpressing these microRNAs in cultured human tumour cells had no significant effect on growth.

We have shown that certain microRNAs are expressed higher in xenograft models when compared to their corresponding in vitro cultured cells. Determining the species origin of these microRNAs identifies that there is a large contribution of microRNA expression from stromal cells. These microRNAs had no effect on tumour cells, likely indicating a more biologically relevant role in the stroma. Furthermore, this data also provides a cautionary tale for interpreting microRNA profiles where the results from a MPM biopsy may include microRNAs contributed by stromal cells.