Molecular Events Regulating Clear Cell Renal Cell Cancer Resistance to Tyrosine Kinase Inhibitors.

e15600 Background: Cancer cell drug resistance is regulated by arising molecular and biochemical abnormalities in cancer cell on one hand and by tumor micro-environmental factors on the other. A complex network of different cell-cell and cell-matrix interactions and auto-, para- and endocrine signals influence ccRCC cells proliferation. These molecular factors are also responsible for tyrosine kinase inhibitors resistance and RCC disease progression. Aims of this study included analysis of hypoxia, IL-6, triiodothyronine, insulin and insulin-like growth factors impact on the proliferation and metastatic potential of ccRCC cells under TKI treatment. The second aim was to measure the effect of niche factors including 3D interactions on TKI activity on ccRCC cells including cancer stem cells. The goal of this research was to enable understanding of cellular events responsible for clinically relevant TKI resistance. Methods: ccRCC cells from primary and metastatic tumors (ATCC, MSKCC collection) along with ccRCC cancer progenitor cells (CD133+) were cultured in normoxic or hypoxic conditions; cells were cultured in defined media and induced by T3, IN or IGF; and/or inhibited by IL-6, TRβ antagonist, sunitinib, sorafenib and axitinib in 2D and 3D conditions. Cell proliferation and TKI toxicity were evaluated (Alamar Blue/MTT). FACS and ICC analysis was undertaken to verify mesenchymal stem cell markers expression. Colony formation potential was evaluated and TRβ/IL-6R/STAT3 gene expression was evaluated with RealTime-RT PCR , WB. Normal kidney proximal tube cells were used as negative control. Results: ccRCC cells including cancer stem cells proliferation may be promoted by hypoxia T3, IN, IL-6sR and IGF in primary tumor and metastatic sites. Conclusions: Multiple micro-environmental factors modify the ccRCC cells resistance to TKI. Understanding of the complex interactions between cancer cells and the 3D microenvironment may enable the identification of novel treatment targets. (Sponsored by: UMO-2012/05/D/NZ5/01844, 2011/01/B/NZ4/01602, Lider/031/625/L-4/NCBR/2013 and CRU/WIM/275/2012)