Supplementary Data PDF file - 600K, Table S1 shows the selection of the lead candidate EZN-3920 based on its specificity and potency in cells. Table S2 describes the potency of EZN-3920 in multiple cancer cell lines. Fig. S1 shows that specific inhibition of HER3 protein and its downstream signaling molecule, phospho-AKT results in cellular death of 15PC3 prostate cancer cells. Fig. S2. shows specific HER3 mRNA down-regulation by EZN-3920 in the absence of lipofection in 15PC3 prostate cancer cells. Fig. S3. shows potent down-regulation of HER3 in the liver of mice treated with EZN-3920 simply dissolved in saline. Fig. S4. shows that treatment of EZN-3920 is capable of blocking gefitinib induced up-regulation of HER3 in the HCC827 tumors. Fig. S5. Shows that cell lines resistant to gefitinib or transtuzumab remains sensitive to EZN-3920. Fig. S6. Shows that treatment EZN-3920 down-regulates HER3 as well as its down-stream signaling molecules in cancer cells
ARTICLE ABSTRACT
Among the four human EGF receptor (HER) family members (EGFR, HER2, HER3, HER4), HER3 is of particular interest as it interacts with HER2 and EGFR via heterodimerization and is a key link to the phosphoinositide 3-kinase (PI3K)/AKT signal transduction axis. Recent studies indicate that HER3 plays a critical role in mediating resistance to agents that target EGFR or HER2. As HER3 lacks significant kinase activity and cannot be inhibited by tyrosine kinase inhibitors, neutralizing antibodies and alternative inhibitors of HER3 have been sought as cancer therapeutics. We describe here a locked nucleic acid (LNA)-based HER3 antisense oligonucleotide, EZN-3920, that specifically downmodulated the expression of HER3, which was associated with growth inhibition. EZN-3920 effectively downmodulated HER3 expression, HER3-driven PI3K/AKT signaling pathway, and growth in tumors derived from BT474M1 breast and HCC827 lung carcinoma cell lines, which overexpress HER2 and EGFR, respectively. Furthermore, when EZN-3920 was coadministered with gefitinib or lapatinib in xenograft tumor models, enhanced antitumor activity compared with the effect of monotherapy was found. The effect was associated with a blockade of induced HER3 mRNA expression caused by lapatinib or gefitinib treatment. Finally, EZN-3920 sustained its antiproliferative effect in trastuzumab-resistant cells and three independently derived gefitinib-resistant cells. Our findings show that downmodulation of HER3 by EZN-3920 leads to the suppression of tumor growth in vitro and in vivo, suggesting that HER3 can be an effective target for the treatment of various cancers that have been activated by HER3 alone or where HER3 activation is associated with EGFR or HER2 expression. Mol Cancer Ther; 12(4); 427–37. ©2013 AACR.
