O25 Expression of polymeric immunoglobulin receptor (PIGR) and the effect of PIGR overexpression on breast cancer cells

Polymeric immunoglobulin receptor (PIGR) has a major role in mucosal immunity as a transporter of polymeric immunoglobulin across the epithelial cells. PIGR expression increases in various cancers and relates to patient outcomes. Functional roles of PIGR have been explored in several cancers such as hepatocellular, pancreatic and lung cancer. The aim of this study was to determine the effect of PIGR on cellular behaviours and chemo-sensitivity of MCF7 and MDA-MB468 breast cancer cell lines. Method Basal levels of PIGR mRNA and protein expression in MCF7 and MDA-MB468 cells were evaluated by real time quantitative polymerase chain reaction and Western blotting, respectively. MCF7/PIGR and MDA-MB468/PIGR stable cell lines, overexpressing the PIGR gene, were generated using a lentiviral vector with tetracycline dependent induction of expression. Cell viability, cell proliferation and chemo-sensitivity of PIGR transfected cells were evaluated and compared with un-transfected cells to determine the effect of PIGR overexpression on cell phenotype. Result The levels of PIGR mRNA and protein expression were significantly higher in MDA-MB468 cells than in MCF7 cells (380-fold, P < 0.0001). However, the differential expression of PIGR in these two cell lines did not lead to significant differences in chemo-sensitivity. Viral overexpression of PIGR was also not found to change any of the parameters measured in either cell line. Conclusion PIGR per se does not affect cellular behaviours and chemo-sensitivity of these breast cancer cell lines. It may be a marker which works through other factors rather than being a direct contributor of the favourable outcome in patients. Take-home Message PIGR may be a marker of favourable outcome in breast cancer patients which works through other factors rather than being a direct contributor.