Circulating tumor cells expressing cancer stem cell marker CD44 as a diagnostic biomarker in patients with gastric cancer - PubMed (original) (raw)
Circulating tumor cells expressing cancer stem cell marker CD44 as a diagnostic biomarker in patients with gastric cancer
Toru Watanabe et al. Oncol Lett. 2017 Jan.
Abstract
Epithelial cell adhesion molecule (EpCAM) is a marker for circulating tumor cells (CTCs) in various types of cancer, while cluster of differentiation 44 (CD44) is a marker for gastric cancer (GC) stem cells. To evaluate the clinical significance of CD44+ CTCs in patients with GC in the present study, the number of EpCAM+CD44+ and EpCAM+CD44- cells were detected in the peripheral blood of 26 GC patients and 12 healthy volunteers using flow cytometry. The number (mean ± standard deviation) of EpCAM+CD44+ cells in the GC patients and healthy volunteers was 69.9±52.0 and 0.91±2.10, respectively (P=0.0001), while that of EpCAM+CD44- cells was 59.1±88.0 and 9.83±9.91, respectively (P=0.0313). The sensitivity and specificity of EpCAM+CD44+ cell detection for the identification of GC patients were 92.3 and 100%, respectively. By contrast, the values of EpCAM+CD44- cell detection were 76.9 and 83.3%, respectively. The number of EpCAM+CD44+ cells in the GC patients was correlated with the disease stage (P=0.0423), the depth of the tumor (P=0.0314) and venous invasion (P=0.0184) in the resected tumor specimens, while the number of EpCAM+CD44- cells did not correlate with any clinicopathological factors. The number of EpCAM+CD44+ cells significantly decreased following surgical resection of the tumor or induction of systemic chemotherapy. Additionally, atypical cells with a high nuclear to cytoplasmic ratio were morphologically detected in the sorted EpCAM+CD44+ cells. These results suggested that CD44+ CTCs, but not CD44- CTCs, reflect the malignant status of the primary tumor in patients with GC, providing a candidate biomarker for diagnosis and treatment response.
Keywords: circulating tumor cells; cluster of differentiation 44; epithelial cell adhesion molecule; flow cytometry; gastric cancer.
Figures
Figure 1.
A comparison of EpCAM+ and/or CD44+ CTC, circulating tumor cell counts in the peripheral blood of healthy volunteers and patients with gastric cancer. Fluorescence-activated cell sorting data from (A) a healthy volunteer and (B) a patient with gastric cancer. All WBCs are EpCAM− cells and CD44 was expressed not only on circulating stem cells, but also in a proportion of WBCs. Thus, typical WBCs are found in Q3 or Q4. Q1 shows EpCAM+CD44− cells and Q2 shows EpCAM+CD44+ cells. WBC, white blood cell; EpCAM, epithelial cell adhesion molecule; CD44, cluster of differentiation 44; APC, allophycocyanin; FITC, fluorescein isothiocyanate.
Figure 2.
A comparison of EpCAM+CD44+ CTC counts in the peripheral blood of healthy volunteers and patients with GC. Mean data are shown. All patients with GC had EpCAM+CD44+ CTCs, whereas only 2 out of 10 healthy volunteers had EpCAM+CD44+ CTCs. GC, gastric cancer; EpCAM, epithelial cell adhesion molecule; CD44, cluster of differentiation 44; CTC, circulating tumor cell.
Figure 3.
A comparison of EpCAM+CD44- CTC counts in the peripheral blood of healthy volunteers and patients with GC. Mean data are shown. EpCAM+CD44- CTCs were detected in all subjects.
Figure 4.
Immunofluorescent staining of sorted EpCAM+CD44+ circulating tumor cells. This cell shows strong staining with EpCAM-APC (red staining) and CD44-FITC (green staining). The cell was identified as a 20-µm heterocyst with a high nuclear to cytoplasmic ratio (original magnification, ×400). EpCAM, epithelial cell adhesion molecule; CD44, cluster of differentiation 44; APC, allophycocyanin; FITC, fluorescein isothiocyanate; >N/C, high nuclear to cytoplasmic ratio.
Figure 5.
EpCAM+CD44+ CTC counts pre- and post-gastrectomy. Mean data are shown from the 25 patients who underwent gastrectomy. EpCAM+CD44+ CTC counts decreased in all cases following surgery. EpCAM, epithelial cell adhesion molecule; CD44, cluster of differentiation 44; CTC, circulating tumor cell.
Figure 6.
Immunohistochemical evaluation of the resected primary tumor. CK-Oscar staining was used a positive control to indicate tumorous tissue. In advanced GC, almost all cancer cells were stained with EpCAM and CD44. By contrast, in early GC, EpCAM-stained cells were present in almost all cancer cells, but only a few CD44-stained cells were present (original magnification, ×400). GC, gastric cancer; EpCAM, epithelial cell adhesion molecule; CD44, cluster of differentiation 44.
Figure 7.
Alterations in EpCAM+CD44+ CTC counts in response to chemotherapy. During second-line PTX-based chemotherapy, EpCAM+CD44+ CTC counts decreased, gradually reaching undetectable levels after 3 weeks. EpCAM, epithelial cell adhesion molecule; CD44, cluster of differentiation 44; CTC, circulating tumor cell; PTX, paclitaxel; CT, computed tomography.
Figure 8.
Computed tomography images showing tumor shrinkage following chemotherapy. After one course of second-line paclitaxel-based chemotherapy, according to the Response Evaluation Criteria in Solid Tumors, the main gastric tumor surrounding the stent showed a partial response of ~30% reduction.
References
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