Aurora kinase A (AURKA) is frequently overexpressed in several cancers. miRNA sequencing and bioinformatics analysis indicated significant downregulation of miR-4715-3p. We found that miR-4715-3p has putative binding sites on the 3UTR region of AURKA. Upper gastrointestinal adenocarcinoma (UGC) tissue samples and cell models demonstrated significant overexpression of AURKA with downregulation of miR-4715-3p. Luciferase reporter assays confirmed binding of miR-4715-3p on the 3UTR region of AURKA. miR-4715-3p mediated a reduction in AURKA levels leading to G2/M delay, chromosomal polyploidy, and cell death. We also detected a remarkable decrease in GPX4, an inhibitor of ferroptosis, with an increase in cleaved PARP and caspase-3. Inhibition of AURKA using siRNA produced similar results, suggesting a possible link between AURKA and GPX4. Analysis of UGC samples and cell models demonstrated increased methylation levels of several CpG nucleotides upstream of miR-4715-3p. 5-Aza-2′-deoxycytidine induced demethylation of several CpG nucleotides, restoring miR-4715-3p expression, leading to downregulation of AURKA. In conclusion, our data identified a novel epigenetic mechanism mediating silencing of miR-4715-3p and induction of AURKA in UGCs. Inhibition of AURKA or reconstitution of miR-4715-3p inhibited GPX4 and induced cell death, suggesting a link between AURKA and ferroptosis.

Background & Aims: Activation of KRAS signaling and overexpression of the aurora kinase A (AURKA) are often detected in luminal gastrointestinal cancers. We investigated regulation of

TFF1, a secreted protein, plays an essential role in keeping the integrity of gastric mucosa and its barrier function. Loss of TFF1 expression in the TFF1-knockout (KO) mouse leads to a pro-inflammatory phenotype with a cascade of gastric lesions that include low-grade dysplasia, high-grade dysplasia, and adenocarcinomas. In this study, we demonstrate nuclear localization of p-STAT Y705 , with significant overexpression of several STAT3 target genes in gastric glands from the TFF1 - KO mice. We also show frequent loss of TFF1 with nuclear localization of STAT3 in human gastric cancers. The reconstitution of TFF1 protein in human gastric cancer cells and 3D gastric glands organoids from TFF1-KO mice abrogates IL6-induced nuclear p-STAT3 Y705 expression. Reconstitution of TFF1 inhibits IL6-induced STAT3 transcription activity, suppressing expression of its target genes. TFF1 blocks IL6Rα-GP130 complex formation through interfering with binding of IL6 to its receptor IL6Rα. These findings demonstrate a functional role of TFF1 in suppressing gastric tumorigenesis by impeding the IL6-STAT3 pro-inflammatory signaling axis.

BackgroundThe incidence of esophageal adenocarcinoma (EAC) is rising rapidly in the US and Western countries. The development of Barrett’s esophagus (BE) and its progression to EAC have been linked to chronic gastroesophageal reflux disease (GERD). Exposure of BE and EAC cells to acidic bile salts (ABS) in GERD conditions induces high levels of oxidative stress and DNA damage. In this study, we investigated the role of insulin-like growth factor binding protein 2 (IGFBP2) in regulating ABS-induced DNA double-strand breaks.MethodsReal-time RT-PCR, western blot, immunohistochemistry, immunofluorescence, co-immunoprecipitation, flow cytometry, and cycloheximide (CHX) chase assays were used in this study. To mimic GERD conditions, a cocktail of acidic bile salts (pH 4) was used in 2D and 3D organotypic culture models. Overexpression and knockdown of IGFBP2 in EAC cells were established to examine the functional and mechanistic roles of IGFBP2 in ABS-induced DNA damage.ResultsOur results demonstrated high levels of IGFBP2 mRNA and protein in EAC cell lines as compared to precancerous Barrett’s cell lines, and IGFBP2 is frequently overexpressed in EACs (31/57). Treatment of EAC cells with ABS, to mimic GERD conditions, induced high levels of IGFBP2 expression. Knocking down endogenous IGFBP2 in FLO1 cells (with constitutive high levels of IGFBP2) led to a significant increase in DNA double-strand breaks and apoptosis, following transient exposure to ABS. On the other hand, overexpression of exogenous IGFBP2 in OE33 cells (with low endogenous levels of IGFBP2) had a protective effect against ABS-induced double-strand breaks and apoptosis. We found that IGFBP2 is required for ABS-induced nuclear accumulation and phosphorylation of EGFR and DNA-PKcs, which are necessary for DNA damage repair activity. Using co-immunoprecipitation assay, we detected co-localization of IGFBP2 with EGFR and DNA-PKcs, following acidic bile salts treatment. We further demonstrated, using cycloheximide chase assay, that IGFBP2 promotes EGFR protein stability in response to ABS exposure.ConclusionsIGFBP2 protects EAC cells against ABS-induced DNA damage and apoptosis through stabilization and activation of EGFR - DNA-PKcs signaling axis.Electronic supplementary materialThe online version of this article (10.1186/s13046-018-1021-y) contains supplementary material, which is available to authorized users.

Neovascularization is the pathological driver of blinding eye diseases such as retinopathy of prematurity, proliferative diabetic retinopathy, and wet age-related macular degeneration. The loss of vision resulting from these diseases significantly impacts the productivity and quality of life of patients, and represents a substantial burden on the health care system. Current standard of care includes biologics that target vascular endothelial growth factor (VEGF), a key mediator of neovascularization. While anti-VGEF therapies have been successful, up to 30% of patients are non-responsive. Therefore, there is a need for new therapeutic targets, and small molecule inhibitors of angiogenesis to complement existing treatments. Apelin and its receptor have recently been shown to play a key role in both developmental and pathological angiogenesis in the eye. Through a cell-based high-throughput screen, we identified 4-aminoquinoline antimalarial drugs as potent selective antagonists of APJ. The prototypical 4-aminoquinoline, amodiaquine was found to be a selective, non-competitive APJ antagonist that inhibited apelin signaling in a concentration-dependent manner. Additionally, amodiaquine suppressed both apelin-and VGEF-induced endothelial tube formation. Intravitreal amodaiquine significantly reduced choroidal neovascularization (CNV) lesion volume in the laser-induced CNV mouse model, and showed no signs of ocular toxicity at the highest doses tested. This work firmly establishes APJ as a novel, chemically tractable therapeutic target for the treatment of ocular neovascularization, and that amodiaquine is a potential candidate for repurposing and further toxicological, and pharmacokinetic evaluation in the clinic.

Unfolded protein response (UPR) protects malignant cells from endoplasmic reticulum stress-induced apoptosis. We report that Aurora kinase A (AURKA) promotes cancer cell survival by activating UPR in esophageal adenocarcinoma (EAC). A strong positive correlation between AURKA and binding immunoglobulin protein (BIP) mRNA expression levels was found in EACs. The in vitro assays indicated that AURKA promoted IRE1α protein phosphorylation, activating prosurvival UPR in FLO-1 and OE33 cells. The use of acidic bile salts to mimic reflux conditions in patients induced high AURKA and IRE1α levels. This induction was abrogated by AURKA knockdown in EAC cells. AURKA and p-IRE1α protein colocalization was observed in neoplastic gastroesophageal lesions of the L2-IL1b mouse model of Barrett’s esophageal neoplasia. The combined treatment using AURKA inhibitor and tunicamycin synergistically induced cancer cell death. The use of alisertib for AURKA inhibition in the EAC xenograft model led to a decrease in IRE1α phosphorylation with a significant reduction in tumor growth. These results indicate that AURKA activates UPR, promoting cancer cell survival during ER stress in EAC. Targeting AURKA can significantly reverse prosurvival UPR signaling mechanisms and decrease cancer cell survival, providing a promising approach for the treatment of EAC patients.

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