Inhibition of AURKA Reduces Proliferation and Survival of Gastrointestinal Cancer Cells With Activated KRAS by Preventing Activation of RPS6KB1.

Activation of KRAS signaling and overexpression of the aurora kinase A (AURKA) are often detected in luminal gastrointestinal cancers. We investigated regulation of ribosomal protein S6 kinase B1 (RPS6KB1) by AURKA and the effects of alisertib, an AURKA inhibitor, in mice xenograft tumors grown from human gastrointestinal cancer cells with mutant, activated forms of KRAS. We tested the effects of alisertib or AURKA overexpression or knockdown in 10 upper gastrointestinal or colon cancer cell lines with KRAS mutations or amplifications using the CellTiter-Glo luminescence and clonogenic cell survival assays. We used the proximity ligation in situ assay to evaluate protein co-localization and immunoprecipitation to study protein interactions. Nude mice with xenograft tumors grown from HCT116, SNU-601, SW480, or SNU-1 cells were given oral alisertib (40 mg/kg, 5 times/wk) for 4 weeks. Tumor samples were collected and analyzed by immunoblots and immunohistochemistry. Tissue microarrays from 151 paraffin-embedded human colon tumors, with adjacent normal and adenoma tissues, were analyzed by immunohistochemistry for levels of AURKA. Alisertib reduced proliferation and survival of the cell lines tested. AURKA knockdown or inhibition with alisertib reduced levels of phosphorylated RPS6KB1 (at T389) and increased levels of proteins that induce apoptosis, including BIM, cleaved PARP, and cleaved caspase 3. AURKA co-localized and interacted with RPS6KB1, mediating RPS6KB1 phosphorylation at T389. We detected AURKA-dependent phosphorylation of RPS6KB1 in cell lines with mutations in KRAS but not in cells with wild-type KRAS. Administration of alisertib to mice with xenograft tumors significantly reduced tumor volumes (P < .001). Alisertib reduced phosphorylation of RPS6KB1 and Ki-67 and increased levels of cleaved caspase 3 in tumor tissues. In analyses of tissue microarrays, we found significant overexpression of AURKA in gastrointestinal tumor tissues compared with non-tumor tissues (P = .0003). In studies of gastrointestinal cancer cell lines with activated KRAS, we found AURKA to phosphorylate RPS6KB1, promoting cell proliferation and survival and growth of xenograft tumors in mice. Agents that inhibit AURKA might slow the growth of gastrointestinal tumors with activation of KRAS.

Wang-Bishop L ，Chen Z ，Gomaa A ，Lockhart AC ，Salaria S ，Wang J ，Lewis KB ，Ecsedy J ，Washington K ，Beauchamp RD ，El-Rifai W ... -  《-》

Synergy of EGFR and AURKA Inhibitors in KRAS-mutated Non-small Cell Lung Cancers.

Bagnyukova T ，Egleston BL ，Pavlov VA ，Serebriiskii IG ，Golemis EA ，Borghaei H ... -  《-》

The combination of alisertib, an investigational Aurora kinase A inhibitor, and docetaxel promotes cell death and reduces tumor growth in preclinical cell models of upper gastrointestinal adenocarcinomas.

Upper gastrointestinal adenocarcinomas (UGCs) respond poorly to current chemotherapeutic regimes. The authors and others have previously reported frequent Aurora kinase A (AURKA) gene amplification and mRNA and protein overexpression in UGCs. The objective of the current study was to determine the therapeutic potential of alisertib (MLN8237) alone and in combination with docetaxel in UGCs. After treatment with alisertib and/or docetaxel, clonogenic cell survival, cell cycle analyses, Western blot analyses, and tumor xenograft growth assays were carried out to measure cell survival, cell cycle progression, apoptotic protein expression, and tumor xenograft volumes, respectively. By using the AGS, FLO-1, and OE33 UGC cell lines, which have constitutive AURKA overexpression and variable tumor protein 53 (p53) status, significantly enhanced inhibition of cancer cell survival was observed with alisertib and docetaxel treatment in combination (P < .001), compared with single-agent treatments. Cell cycle analyses, after 48 hours of treatment with alisertib, produced a significant increase in the percentage of polyploidy in UGC cells (P < .01) that was further enhanced by docetaxel (P < .001). In addition, an increase in the percentage of cells in sub-G1-phase observed with alisertib (P < .01) was significantly enhanced with the combination treatment (P < .001). Western blot analysis demonstrated higher induction of cleaved caspase 3 protein expression with the combined treatment compared with single-agent treatments. In addition, FLO-1 and OE33 cell xenograft models demonstrated enhanced antitumor activity for the alisertib and docetaxel combination compared with single-agent treatments (P < .001). The current study demonstrated that alisertib combined with docetaxel can mediate a better therapeutic outcome in UGC cell lines.

Sehdev V ，Katsha A ，Ecsedy J ，Zaika A ，Belkhiri A ，El-Rifai W ... -  《-》

Activation of EIF4E by Aurora Kinase A Depicts a Novel Druggable Axis in Everolimus-Resistant Cancer Cells.

Purpose: Aurora kinase A (AURKA) is overexpressed in several cancer types, making it an attractive druggable target in clinical trials. In this study, we investigated the role of AURKA in regulating EIF4E, cap-dependent translation, and resistance to mTOR inhibitor, RAD001 (everolimus).Experimental Design: Tumor xenografts and in vitro cell models of upper gastrointestinal adenocarcinomas (UGC) were used to determine the role of AURKA in the activation of EIF4E and cap-dependent translation. Overexpression, knockdown, and pharmacologic inhibition of AURKA were used in vitro and in vivoResults: Using in vitro cell models, we found that high protein levels of AURKA mediate phosphorylation of EIF4E and upregulation of c-MYC. Notably, we detected overexpression of endogenous AURKA in everolimus-resistant UGC cell models. AURKA mediated phosphorylation of EIF4E, activation of cap-dependent translation, and an increase in c-MYC protein levels. Targeting AURKA using genetic knockdown or a small-molecule inhibitor, alisertib, reversed these molecular events, leading to a decrease in cancer cell survival in acquired and intrinsic resistant cell models. Mechanistic studies demonstrated that AURKA binds to and inactivates protein phosphatase 2A, a negative regulator of EIF4E, leading to phosphorylation and activation of EIF4E in an AKT-, ERK1/2-, and mTOR-independent manner. Data from tumor xenograft mouse models confirmed that everolimus-resistant cancer cells are sensitive to alisertib.Conclusions: Our results indicate that AURKA plays an important role in the activation of EIF4E and cap-dependent translation. Targeting the AURKA-EIF4E-c-MYC axis using alisertib is a novel therapeutic strategy that can be applicable for everolimus-resistant tumors and/or subgroups of cancers that show overexpression of AURKA and activation of EIF4E and c-MYC. Clin Cancer Res; 23(14); 3756-68. ©2017 AACR.

Katsha A ，Wang L ，Arras J ，Omar OM ，Ecsedy J ，Belkhiri A ，El-Rifai W ... -  《-》

Inhibition of mitotic Aurora kinase A by alisertib induces apoptosis and autophagy of human gastric cancer AGS and NCI-N78 cells.

Yuan CX ，Zhou ZW ，Yang YX ，He ZX ，Zhang X ，Wang D ，Yang T ，Wang NJ ，Zhao RJ ，Zhou SF ... -  《Drug Design Development and Therapy》