Role of rpL3 in the translational reprogramming of colon cancer cells resistant to 5-FU”

In the last years, a lot of evidences have been accumulated suggesting that translational reprogramming plays a key role in tumor initiation, invasion and multidrug resistance (MDR). Translational reprogramming is associated to alteration in eukaryotic translation initiation factors (eIFs) activity, in particular the overexpression of the eIF4F complex, is associated with chemoresistance in melanoma, colon and thyroid cancer cell lines. In our previously study, we have analyzed the role of human ribosomal protein rpL3 in MDR. Our studies revealed that rpL3 is a key determinant in cellular stress responce and in MDR in HCT 116p53-/- cells. Here we report results from GST pull-down and mass spectrometry demonstrating that eiF4A, a component of eIF4F complex, is able to interact with rpL3 in vitro. Immunoprecipitation experiments confirm the presence of a complex rpL3/eiF4A/eiF4G in HCT 116p53-/- cells treated with 5-FU. The translation status of known mRNAs regulated by eIF4A (i.e. BCL2-family, Cyclins and c-Myc mRNAs) has been analyzed by qPCR in 5-FU resistant HCT 116p53-/- cells and in L3DHCT 116p53-/- cells. Results from these experiments will be presented.