Supplementary Material

Transcription

1 Supplementary Material The Androgen Receptor is a negative regulator of eif4e Phosphorylation at S209: Implications for the use of mtor inhibitors in advanced prostate cancer Supplementary Figures Supplemental Figure 1. Effect of the strong androgen receptor inhibitor enzalutamide in combination with the second generation mtor inhibitors BEZ235 or INK128 in PC346C, C4-2 and C4-2b cells. (A, B) MTT viability assay of PC346C and C4-2b cells treated with 10nM of BEZ235 alone or in combination with 1uM of enzalutamide. (C, D) MTT viability assay of PC346C and C4-2 cells treated with 25nM of INK128 alone or in combination with 1uM of enzalutamide. C4-2 and C4-2b, which is a sub-cell line of C4-2, were more susceptible to the mtor inhibitors alone or in combination with enzalutamide while PC346C showed little effect to BEZ235 alone or in combination. INK128 was more effective against PC346C but not to the extent of the effect demonstrated in C4-2 cell. 1

2 Supplemental Figure 2. Effect of the mtor inhibitor RAD001 alone on mtor pathway proteins in C4-2 and PC346C cells. Western blot of C4-2 and PC346C treated with RAD001 for different time points up to 4 days depicting the effect of mtor inhibition on the expression and phosphorylation of various proteins. RAD001 alone is sufficient to inhibit mtor activity shown by the decrease phosphorylation of its both direct targets, 4EBP1 and P70S6K but increased eif4e phosphorylation in C4-2. Right panel shows a very low exposure of eif4e phosphorylation in PC-346C cells, where eif4e phosphorylation levels are very high. Supplemental Figure 3. Effect of different mtor inhibitors in the nontumor prostate line prns1-1 transfected with wild type AR. MTT viability assay of PRNS1-1 cells transfected with wild type AR and treated with RAD001, BEZ235 or INK128. The presence of androgen receptor in these cells made them sensitive to mtor inhibitors similar to the transfection of the mutated version (or AR (T877A) demonstrated on figure 3E). 2

3 Supplemental Figure 4. Effect of PTEN over expression on eif4e and Akt phosphorylation and on cell growth in the presence of RAD001 and bicalutamide in C4-2 cells. (A) Western blot of C4-2 cells transfected with empty vector or a plasmid expressing PTEN showing a decrease in phosphorylation of eif4e and Akt. (B-C) MTT viability assay of C4-2 transfected either with control (B) or PTEN overexpression (C) treated with RAD001, Casodex or the combination. 3

4 Supplemental Figure 5. Inhibition of eif4e phosphorylation caused by a Mnk1/2 inhibitor sensitizes CRPC cells to mtor inhibitors and AR antagonists. (A) Western blots of C4-2 cells treated with CGP57380, INK128 and either AR antagonist bicalutamide or enzalutamide and the different combinations for 48 hours. Both AR antagonists increase phosphorylation at Ser209 eif4e which is prevented by addition of the Mnk inhibitor CGP57380 or the strong mtorc1 and C2 inhibitor INK128. (B, C) MTT viability assay of C4-2 and PC346C treated with mtor inhibitor RAD001, AR antagonist enzalutamide and the Mnk inhibitor CGP C4-2 cells are sensitive to mtor inhibition alone, but the resistant cell line PC346C shows decreased viability when Mnk is inhibited by CGP57380 and paired with an mtor inhibitor. (D) Effect of CGP57380, RAD001 or the combination on apoptosis in C4-2 and PC346C measured by Annexin V FITC x PI flow cytometry. 4

5 Supplemental Figure 6. P70S6K phosphorylation inhibition caused by treatment with the Mnk inhibitor CGP Western blots of LNCaP (A), 22Rv1 (B) and CWR-R1 cells (C) treated either with the Mnk inhibitor CGP57380, the mtor C1 and C2 strong inhibitor INK128 or the combination showing effects of Mnk inhibition on P70S6K phosphorylation in PTEN positive (CWR22-R1 and 22Rv1) and negative (LNCaP) cells. (D-E) Western blots of PC346C and C4-2 treated with the PI3K inhibitor BKM120, RAD001, BEZ235, INK128 and the combinations for 48 hours. 5

6 Supplemental Figure 7. mrna transcription levels of the eif4e target proteins surviving, c-myc and Cyclin D1 in C4-2 and PC-346C cells treated with Bicalutamide (BIC), RAD001, or the combination. (A) C4-2 cells were plated in triplicate and treated as shown. mrna expression was determined by qpcr. Data represents mean±s.d. of triplicates, and show the effect of the drug treatments on the expression of survivin, c-myc and cyclin D1. (B) Effect of the same drugs on the expression of the three genes in PC-346C cells. Starred variables represent those significantly different from the corresponding control (p<0.05) as determined by t-test. 6

7 Supplemental Figure 8. Schematic representation of the mtor signaling pathway and targets of the drugs used on this study. mtor acts in complex with raptor (mtorc1) or with rictor (mtorc2). mtorc1 increases mrna translation by phosphorylation of the downstream target eukaryotic initiation factor 4E (eif4e) binding protein 1 (4E-BP1), while mtorc2 activates Akt phosphorylation at Ser473, among other targets. Akt is also phosphorylated by phosphatidylinositol 3-kinase (PI3K) at Thr308 for complete activation, which can phosphorylate key residues on the androgen receptor (AR). The AR inhibits activation of various kinases including Mitogen-Activated Protein Kinase (MAPK) which is activated by AR inhibition by antiandrogens such as bicalutamide and enzalutamide. In the unphosphorylated state, 4E-BP1 binds eif4e and keeps it inactive. 4E-BP1 phosphorylation by mtorc1 releases eif4e which associates with eif4g and eif4a to form the translational initiation complex eif4f. This enables eif4e binding to the m7g cap at the 5 -end of eukaryotic mrnas, which initiates cap-dependent translation. Here, our data indicate that phosphorylation of eif4e at S209 by MAPK-Interacting Kinase 1 and 2 (Mnk1/2) downstream of MAPK activation prevents cap-independent translation, whereas inhibition of Mnk by CGP57380 shifts translation back to a cap-dependent mechanism. 7