Upper gastrointestinal adenocarcinomas (UGCs) of the esophagus and stomach are a major health problem world-wide. Approximately 80% of patients in the United States present with regional or distant metastases. Unfortunately, the mortality rates for UGCs approach incidence rates, suggesting that the available therapeutic options are limited and ineffective. Understanding the molecular biology and signaling networks of UGCs is a critical step in order to develop specific therapies that can potentially improve the outcomes. This proposal stems from our original finding that Aurora kinase A (AURKA) is a critical target at the 20q amplicon that is overexpressed in approximately 60% of UGCs. Our recent studies indicate that the AURKA protein is a potent pro-survival protein that promotes resistance to chemotherapeutic drugs through activation of oncogenic signaling pathways. Our preliminary data demonstrate that AURKA mediates up- regulation and phosphorylation of EIF4E. We have also shown that cells with acquired resistance to mTOR inhibitor RAD001 develop an increase in the protein level of AURKA, as compared to their parental cells, whereas overexpression of AURKA leads to resistance to mTOR inhibitor RAD001. Several recent studies have shown that EIF4E is a key component of cap-dependent translation of several oncogenes such as c- MYC, CCND1, and VEGF. We have uncovered the presence of a novel positive feedback loop of AURKA- EIF4E-MYC that drives cancer cell survival and resistance to therapy. In addition, our data provide evidence that AURKA can bypass key signaling pathways and phosphorylate EIF4E independent of mTOR, AKT and ERK1/2 activities. Based on our novel discoveries, we hypothesize that activation of the AURKA-EIF4E-MYC signaling loop and EIF4E-dependent oncogenic translation drive cancer cell survival as well as resistance to RAD001.
In Aim 1, we will investigate the role of AURKA in regulating EIF4E cap-dependent translation in UGCs. We will investigate the mechanisms and molecular functions of the AURKA-EIF4E-MYC loop in Aim 2.
Aim 3 of this proposal will determine the potential clinical significance of the AURKA-EIF4E-MYC axis. In this aim, we will also investigate the therapeutic potential of targeting the AURKA-EIF4E-MYC axis using AURKA inhibitor MLN8237 alone or in combinations for overcoming resistance to RAD001. Upon completion of our work, we expect to unveil a new paradigm for molecular mechanisms regulating cancer cell survival by AURKA-EIF4E-MYC axis. The translational components of this project have been established with measurable end points that could facilitate the development of better diagnostic, prognostic, and possibly therapeutic interventions. Therefore, our findings will have a positive impact on understanding the biology which could accelerate the development of novel medical treatments for the deadly UGCs.
Esophageal and gastroesophageal junction adenocarcinomas are increasing at alarming levels. In this proposal, we plan to characterize the molecular function(s) of AURKA, a frequently overexpressed gene, in order to identify its biological, diagnostic, prognostic, and possibly therapeutic significance.
|Wang-Bishop, Lihong; Chen, Zheng; Gomaa, Ahmed et al. (2018) Inhibition of AURKA Reduces Proliferation and Survival of Gastrointestinal Cancer Cells With Activated KRAS by Preventing Activation of RPS6KB1. Gastroenterology :|
|Wang, Lihong; Arras, Janet; Katsha, Ahmed et al. (2017) Cisplatin-resistant cancer cells are sensitive to Aurora kinase A inhibition by alisertib. Mol Oncol 11:981-995|
|Peng, DunFa; Guo, Yan; Chen, Heidi et al. (2017) Integrated molecular analysis reveals complex interactions between genomic and epigenomic alterations in esophageal adenocarcinomas. Sci Rep 7:40729|
|Katsha, Ahmed; Wang, Lihong; Arras, Janet et al. (2017) Activation of EIF4E by Aurora Kinase A Depicts a Novel Druggable Axis in Everolimus-Resistant Cancer Cells. Clin Cancer Res 23:3756-3768|
|Chen, Zheng; Soutto, Mohammed; Rahman, Bushra et al. (2017) Integrated expression analysis identifies transcription networks in mouse and human gastric neoplasia. Genes Chromosomes Cancer 56:535-547|
|Katsha, Ahmed; Belkhiri, Abbes; Goff, Laura et al. (2015) Aurora kinase A in gastrointestinal cancers: time to target. Mol Cancer 14:106|
|Belkhiri, Abbes; El-Rifai, Wael (2015) Advances in targeted therapies and new promising targets in esophageal cancer. Oncotarget 6:1348-58|
|Sehdev, Vikas; Katsha, Ahmed; Arras, Janet et al. (2014) HDM2 regulation by AURKA promotes cell survival in gastric cancer. Clin Cancer Res 20:76-86|
|Katsha, Ahmed; Arras, Janet; Soutto, Mohammed et al. (2014) AURKA regulates JAK2-STAT3 activity in human gastric and esophageal cancers. Mol Oncol 8:1419-28|
|Katsha, Ahmed; Soutto, Mohammed; Sehdev, Vikas et al. (2013) Aurora kinase A promotes inflammation and tumorigenesis in mice and human gastric neoplasia. Gastroenterology 145:1312-22.e1-8|
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