Celecoxib-Induced Modulation of Colon Cancer CD133 Expression Occurs through AKT Inhibition and Is Monitored by ⁸⁹Zr Immuno-PET

Abstract

We developed an immuno-PET technique that monitors modulation of tumor CD133 expression, which is required for the success of CD133-targeted therapies. Methods. Anti-CD133 antibodies were subjected to sulfhydryl moiety-specific 89Zr conjugation. 89Zr-CD133 IgG was evaluated for specific activity and radiolabel stability. Colon cancer cells underwent binding assays and Western blotting. Biodistribution and PET studies were performed in mice. Results. 89Zr-CD133 IgG showed excellent target specificity with 97.2 ± 0.7 % blocking of HT29 cell binding by an excess antibody. Intravenous 89Zr-CD133 IgG followed biexponential blood clearance and showed CD133-specific uptake in HT29 tumors. 89Zr-CD133 IgG PET/CT and biodistribution studies confirmed high HT29 tumor uptake with lower activities in the blood and normal organs. In HT29 cells, celecoxib dose-dependently decreased CD133 expression and 89Zr-CD133 IgG binding that reached 19.9 ± 2.1 % ( P < 0.005 ) and 50.3 ± 10.9 % ( P < 0.001 ) of baseline levels by 50 μM, respectively. Celecoxib treatment of mice significantly suppressed tumor CD133 expression to 67.5 ± 7.8 % of controls ( P < 0.005 ) and reduced tumor 89Zr-CD133 IgG uptake from 15.5 ± 1.4 % at baseline to 12.3 ± 2.0 % ID / g ( P < 0.01 ). Celecoxib-induced CD133 reduction in HT29 cells and tumors was associated with substantial suppression of AKT activation. There were also reduced HIF-1α accumulation and IκBα/NFκB phosphorylation. Conclusion. 89Zr-CD133 IgG PET provides high-contrast tumor imaging and monitors celecoxib treatment-induced modulation of tumor CD133 expression, which was found to occur through AKT inhibition. This technique may thus be useful for screening drugs that can effectively suppress colon cancer stem cells.

Cysteine-specific 89Zr-labeled anti-CD25 IgG allows immuno-PET imaging of interleukin-2 receptor-α on T cell lymphomas

“…Our group has shown that mild reaction with TCEP induces cysteine site-specific reduction of Abs for DFO conjugation, which likely occurs at the two hinge region disulfide bonds ( 29 ). We have successfully used this straightforward site-specific 89 Zr labeling method for immuno-PET of tumor CD44 ( 27 ), CD133 ( 28 ), programmed cell death ligand-1 ( 29 ), and programmed cell death-1 ( 30 ).…”

Immuno-PET Imaging and Radioimmunotherapy of Lymphomas

“…The conjugation technique was straightforward and required only a short 1 h reaction time at room temperature. The resulting 89 Zr-labeled Abs demonstrated high affinity and specific target antigen binding in vitro and high-contrast PET imaging in vivo. − …”

Informed by Cancer Stem Cells of Solid Tumors: Advances in Treatments Targeting Tumor-Promoting Factors and Pathways

“…Celecoxib, which is a non-steroidal antiinflammatory drug, inhibits the expression of CD133 in HT29 and DLD1 colorectal cancer cells via suppressing the Wnt signaling pathway [275]. Conversely, other studies have suggested that celecoxib-induced downregulation of CD133 is mediated by AKT inhibition in HT29 cells [276]. Trifluridine, a drug that is currently in clinics for the management of refractory colorectal cancer inhibits spheroid formation in CD133 + DLD1 colorectal cancer cells, suggesting a potential mechanism for its anti-cancer activity [277].…”