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Smit JK, Niemantsverdriet M, van Os RP, Hollema H, Plukker JT, Coppes RP. Evaluation of esophageal carcinoma for a radioresistant subpopulation with cancer stem cell characteristics. J Clin Oncol 2011. [DOI: 10.1200/jco.2011.29.4_suppl.36] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
36 Background: Neo-adjuvant chemoradiation is considered as standard treatment in esophageal cancer (EC). However, a significant proportion of these tumors do not respond well to radiotherapy. Here, we investigated the presence of radioresistant cells in EC with cancer stem cell characteristics. Methods: EC OE-33 adenotype and OE-21 squamous cell carcinoma cell-lines and fresh tumor material of EC patients were analyzed for common CSC-markers with Fluorecence Activated Cell Sorting (FACS) and immunohistochemistry. Subpopulations were tested for clonogenic survival to determine radioresistance. Non-adherent 3D sphere-cultures and xenograft tumors generated in NOD/SCID mice were performed to investigate stem cell properties. Results: Both cell lines lacked expression of CD133 and CD90, whereas the expression of EpCam overlapped with CD44 in OE-33. In sub-confluent cultures the expression of CD44+/CD24- was 5.6% SD ± 2.3 and 35.1% SD ± 1.3 in OE-33 and OE-21, respectively. In a clonogenic survival assay the CD44+/CD24- cells showed up to a 2-fold lower radiosensitivity compared to CD44+/CD24+ cells in both the OE-33 (p = 0.02) and the OE-21 cell line (p = 0.01). The CD44+/CD24- subpopulation had a 2.2-fold higher sphere-forming capacity compared to the CD44+/CD24+ subset (p = 0.01) in OE-33. Analysis of the spheres showed an enrichment in the CD44+/CD24- phenotype from 5.6% to 56.4% (p = 0.01) after 4 days of culturing as measured by FACS, but differentiated to a higher percentage of CD44+/CD24+ in time. Furthermore, CD44+/CD24- cells exhibited a greater in vivo tumor initiating capacity, shorter latency time and faster growth speed compared with unsorted or CD44+/CD24+ cells. Importantly, a clear CD44+/CD24- population could be identified in fresh EC biopsies of patients. Conclusions: EC appear to contain a radioresistant CD44+/CD24- subpopulation. This phenotype displays some CSC characteristics in vitro and in vivo and is present in human EC tumors. This marker could be used in future trials to predict tumor response. No significant financial relationships to disclose.
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Affiliation(s)
- J. K. Smit
- University Medical Center Groningen, Groningen, Netherlands
| | | | - R. P. van Os
- University Medical Center Groningen, Groningen, Netherlands
| | - H. Hollema
- University Medical Center Groningen, Groningen, Netherlands
| | - J. T. Plukker
- University Medical Center Groningen, Groningen, Netherlands
| | - R. P. Coppes
- University Medical Center Groningen, Groningen, Netherlands
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