Abstract 2707: Heat shock protein 90 functional inhibition regulates epithelial to mesenchymal transformation, invasion and migration via NF-kB and HIF-1α signaling in colorectal cancer.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC Purpose/Objectives: Epithelial to mesenchymal transformation (EMT), invasiveness and motility are essential steps in cancer metastasis. HIF-1α and NF-κB have a central role in cancer metastasis. These transcriptional factors (HIF-1α and NF-κB) required HSP90 for stability, folding and trafficking. Ganetespib is a potent functional inhibitor of HSP90 currently under evaluation in clinical trials. We tested the hypothesis that HSP90 functional inhibition by ganetespib can inhibit metastasis in colorectal cell lines. Methods: Two colorectal cancer (CRC) cell lines were used, HCT-116 and HT-29. Cells were either untreated (control) or treated with ganetespib at 50 nM for 24 hours. Western blot and RT-PCR analyses were carried out to determine the effect of ganetespib on different signal molecules involved in metastasis. Electrophoretic mobility shift assay (EMSA) was performed in CRC cells to evaluate the effects of ganetespib on NF-kB activity. Immunocytochemistry assay was also performed. Results: the treatment of colorectal cell lines with ganetespib can inhibit NF-κB and HIF-1α at transcriptional and translational level resulting in inhibition of EMT, invasion and motility. Our investigation also showed that ganetespib treatment significantly (p<0.001) inhibited vimentin and upregulated E-cadherin protein and mRNA levels in both cell lines. Treatment with ganetespib significantly (p<0.001) inhibited matrigel invasion and spheroid migration. In addition, ganetespib treatment significantly (p<0.001) downregulated molecular signaling pathways associated with invasion and motility including uPAR, p70S6K, FAK, MMP2, and MMP9. The overexpression of HIF-1α or NF-κB resulted in increased invasion and motility and its related signaling molecules in both cell lines. Functional inhibition of HSP90 resulted in inhibition of EMT due to NF-κB or HIF-1α downregulation. Similar effects were observed in tumors from animals treated with ganetespib. We also demonstrated the inhibition of HIF-1α, NF-κB and EMT in rectal tumors obtained from patients receiving ganetespib. Conclusion: In this study, we present in vitro, animal, and human data to confirm the role of targeting HSP90 as a method to prevent metastasis of colorectal cancer. We demonstrate for the first time that inhibition of HSP90 downregulates both HIF-1α and NF-κB leading to inhibition of EMT, motility and invasiveness in colorectal cancer. Accordingly, combining HSP90 inhibitors with chemo- or radiotherapy is a rational approach for future drug development in colorectal cancer. Citation Format: Purnachandra Ganji, Tua-Elisabeth Long, Phani Madhuri Mummareddi, Wungki Park, Field F. Willingham, Jerome C. Landry, Patrick Sullivan, LaTonia Taliaferro-Smith, Roberto Diaz, Bassel El-Rayes. Heat shock protein 90 functional inhibition regulates epithelial to mesenchymal transformation, invasion and migration via NF-kB and HIF-1α signaling in colorectal cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2707. doi:10.1158/1538-7445.AM2013-2707