Poster Presentation 27th Lorne Cancer Conference 2015

Flightless I expression affects tumour growth  (#222)

Noraina Muhamad Zakuan 1 2 , Dodie Pouniotis 1 3 , Zlatco Kopecki 4 , Allison Cowin 4 , Ian Darby 1 3
  1. Cancer and Tissue Repair Laboratory, RMIT University, Bundoora, 3083 VIC, Australia
  2. Department of Biomedical Science, University Putra Malaysia, 43400 Serdang, Selangor, Malaysia
  3. School of Medical Sciences, RMIT University, Bundoora, 3083 VIC, Australia
  4. Centre for Regenerative Medicine, Mawson Institute, UniSA, Adelaide, SA 5095, Australia

Noraina M. Zakuan1,2, Dodie S. Pouniotis1,3, Zlatko Kopecki4, Allison Cowin4, Ian A. Darby1,3

1Cancer & Tissue Repair Laboratory, RMIT University, Bundoora, VIC 3083, Australia

2Department of Biomedical Science, University Putra Malaysia, Serdang 43400, Malaysia

3School of Medical Sciences, RMIT University, Bundoora, VIC 3083, Australia

4Centre for Regenerative Medicine, Mawson Institute, UniSA, SA 5095, Australia

Introduction

Flightless I (Flii) is a gelsolin family member that plays a role in cellular motility and adhesion. Flii shows both intracellular and secreted localisation. Previous studies reported that reduced Flii expression enhanced wound healing while overexpression of Flii caused increased scarring. We hypothesised that Flii may have effects on tumour growth and spread. Using a colon carcinoma cell line (CT26) in vivo and in culture, we show that Flii expression has effects on tumour growth and also at the cellular level on migration, proliferation, apoptosis and invasion.

Methods

Wild type mice, mice with reduced Flii expression (Flii+/-) and mice over-expressing Flii (Fliitg) were injected with CT26 cells into the flank or tail vein for in vivo studies of tumour growth.   In vitro, CT26 and HT29 cells were cultured in the presence of recombinant Flii or with Flii siRNA. Scratch assays were performed to determine migration and flow cytometry to examine proliferation and apoptosis. Matrigel invasion assays were performed to determine the effects of Flii expression or exogenous Flii on cell invasion.

Results

A significant increase in the size of primary tumours and more lung tumours were found in Fliitg mice compared to WT or Flii+/- mice. In vitro, knockdown of Flii increased cell migration and proliferation while overexpression of Flii reduced cell migration. Flii knockdown reduced apoptosis while exogenous Flii significantly increased apoptosis. However, Flii knockdown inhibited the invasion of cells in matrigel coated plates.

Conclusion

Our data suggests Flii has effects at the cellular level that suggest a role in tumour growth and spread. In vivo data suggested Flii expression may promote tumour growth and metastasis. In vitro data showed conflicting effects at the cellular level, with both potential tumour promoting and inhibiting effects. The exact mechanisms by which Flii affects tumour cell behaviour remain to be elucidated.