Abstract 3537: P-glycoprotein expression level is responsible for alterations in plasma membrane microfluidity as probed by fluorescence correlation spectroscopy

Abstract

Abstract Expression of P-glycoprotein (P-gp), the multidrug resistance (MDR) 1 gene product, leads to MDR in tumors. By using the fluorescent membrane probe DiA and Fluoresence Correlation Spectroscopy (FCS) to explore the plasma membrane microfluidity, we have previousely shown a showed a decrease in plasma membrane microfluidity in LR73R cells (the Chinese hamster ovarian LR73R cells transfected with MDR1 cDNA) (1). In the present study, and in order to study the relationship between membrane microfluidity and the level of P-gp expression, a strategy using flow cytometry and calcein-AM functional fluorescence-activated cell sorting permitted us to select two cell populations from LR73R cells expressing distinct levels of P-gp (P4 “lower calcein-AM uptake” and P5 “higher calcein-AM uptake”). Data obtained on the cytotoxic effects of doxorubicin (DOX) showed clearly that P4 cells were 10-fold resistant to DOX than P5 cells. A direct correlation between the sensitivity of the cells to DOX and the calcein-AM uptake was observed. In addition, intranuclear DOX measurements using microspectrofluorometry showed a decrease in nuclear accumulation of DOX in P4 cells when compared to P5 cells. This was in agreement with the functional calcein-AM uptake assay. By using the fluorescent membrane probe DiA FCS analysis, we explored the membrane microfluidity in P4 and P5 cells. We show that P5 cells presented an increase in membrane fluidity when compared to P4 cells. LR73 cells presented the highest microfluidity when compared to P4 and P5 cells. This was in agreement with the previous published data (1) and demonstrate also that the microfluidity of the plasma membrane is strongly related to the level of Pgp expression. (1) Boutin C, Roche Y, Millot C, Deturche R, Royer P, Manfait M, Plain JM, Jeannesson P, Millot JM, Jaffiol R. High heterogeneity of plasma membrane microfluidity in multidrug-resistant cancer cells. J Biomed Opt. 2009 14(3): 034030. Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3537.