Stabilization of E-cadherin adhesions by COX-2/GSK3β signaling is a targetable pathway in metastatic breast cancer
Kuppusamy Balamurugan, Dipak K. Poria, Saadiya W. Sehareen, Savitri Krishnamurthy, Wei Tang, Lois McKennett, Veena Padmanaban, Kelli Czarra, Andrew J. Ewald, Naoto T. Ueno, Stefan Ambs, Shikha Sharan, Esta Sterneck
Kuppusamy Balamurugan, Dipak K. Poria, Saadiya W. Sehareen, Savitri Krishnamurthy, Wei Tang, Lois McKennett, Veena Padmanaban, Kelli Czarra, Andrew J. Ewald, Naoto T. Ueno, Stefan Ambs, Shikha Sharan, Esta Sterneck
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Research Article Cell biology Oncology

Stabilization of E-cadherin adhesions by COX-2/GSK3β signaling is a targetable pathway in metastatic breast cancer

Abstract

Metastatic progression of epithelial cancers can be associated with epithelial-mesenchymal transition (EMT) including transcriptional inhibition of E-cadherin (CDH1) expression. Recently, EM plasticity (EMP) and E-cadherin–mediated, cluster-based metastasis and treatment resistance have become more appreciated. However, the mechanisms that maintain E-cadherin expression in this context are less understood. Through studies of inflammatory breast cancer (IBC) and a 3D tumor cell “emboli” culture paradigm, we discovered that cyclooxygenase 2 (COX-2; PTGS2), a target gene of C/EBPδ (CEBPD), or its metabolite prostaglandin E2 (PGE2) promotes protein stability of E-cadherin, β-catenin, and p120 catenin through inhibition of GSK3β. The COX-2 inhibitor celecoxib downregulated E-cadherin complex proteins and caused cell death. Coexpression of E-cadherin and COX-2 was seen in breast cancer tissues from patients with poor outcome and, along with inhibitory GSK3β phosphorylation, in patient-derived xenografts (PDX) including triple negative breast cancer (TNBC).Celecoxib alone decreased E-cadherin protein expression within xenograft tumors, though CDH1 mRNA levels increased, and reduced circulating tumor cell (CTC) clusters. In combination with paclitaxel, celecoxib attenuated or regressed lung metastases. This study has uncovered a mechanism by which metastatic breast cancer cells can maintain E-cadherin–mediated cell-to-cell adhesions and cell survival, suggesting that some patients with COX-2+/E-cadherin+ breast cancer may benefit from targeting of the PGE2 signaling pathway.

Authors

Kuppusamy Balamurugan, Dipak K. Poria, Saadiya W. Sehareen, Savitri Krishnamurthy, Wei Tang, Lois McKennett, Veena Padmanaban, Kelli Czarra, Andrew J. Ewald, Naoto T. Ueno, Stefan Ambs, Shikha Sharan, Esta Sterneck

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Figure 5

Celecoxib combination with paclitaxel attenuates experimental and spontaneous lung metastases.

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Celecoxib combination with paclitaxel attenuates experimental and sponta...
(A) Western blot analysis of the indicated proteins in SUM149 emboli after exposure to 50 μM celecoxib and/or 10 nM paclitaxel for 3 days (total time in 3D, 6 days). (B) Quantification of bioluminescence in the lungs of mice (n = 4) with experimental metastases of SUM149-GFP-Luc cells before (day 0) or after 28 days of treatment with celecoxib (1,000 mg/kg chow) and/or paclitaxel (10 mg/kg i.v.). *P = 0.028 by unpaired 2-sided Wilcoxon rank-sum test. (C) Quantification of bioluminescence in mice (n = 4–5) as in B after 56 days of treatment with celecoxib (500 mg/kg chow) and/or paclitaxel (5 mg/kg i.v.). P values as indicated by unpaired or paired (indicated with #) 2-sided Wilcoxon rank-sum test. (D) Tumor volume measurements of BCM-5471 PDX in mice on day 0 and 22 of treatment as in B (n = 6–10, P values as indicated by 2-sided t test). (E) Western blot analysis of BCM-5471 PDX tumors from mice in D after treatment with paclitaxel ± celecoxib. (F) Quantification of E-cadherin, pGSK3βS9, and COX-2 signals in E (n = 6–8, mean ± SEM; P values by unpaired 2-sided Wilcoxon rank-sum test; *P < 0.05, **P < 0.01). (G) Light microscope image of a mouse lung section from the experiment in D showing representative micrometastases immunostained with human-specific “mitomarker“ (top panel) and their pixilation by the Halo image analysis software (bottom panel). The black arrow points to a micrometastasis. The white arrow points to bronchial tissue. Scale bar: 500 μm. (H) Quantification of tumor cell pixels in representative sections of lungs from mice as in G (% of total lung area, n = 6–10; P = 0.0005 by unpaired Wilcoxon rank-sum test).