Expression of cancer stem cell markers CD44, CD133, and ALDH in a primary tumor before and after platinum-containing chemotherapy in ovarian cancer

Introduction. Ovarian cancer (OC) is characterized by an unfavorable clinical course. Difficulties in the treatment of OC can be due to intratumoral heterogeneity, which includes the presence of stem cells. The aim of this study was to assess the expression of stem markers in the tissue of primary OC before and during chemotherapy of OC in association with the clinical features of the disease. Materials and methods. A retrospective study evaluated tissue samples of the primary tumors of patients (n=28) with stages I–IV epithelial OC obtained before or after 3 courses of chemotherapy. The expression of ALDH, CD44, and CD133 was assessed by immunohistochemistry. Results. In samples of high-grade serous adenocarcinoma, the percentages of cells expressing ALDH (p=0.008), CD44 (p=0.026), and CD133 (p=0.059) were lower than in other subtypes. Tissue samples obtained before treatment showed a higher percentage of cells expressing CD44 (p=0.053) than the ones obtained after neoadjuvant chemotherapy. There was a tendency towards higher expression of CD44 (p=0.056) and ALDH (p=0.074) in stages I–II tumors when compared to that in stages III–IV. In the neoadjuvant chemotherapy group, patients with clinically platinum-sensitive tumors had a higher percentage of CD44+ cells than those with non-platinum-sensitive ones (p=0.038). The number of tumor cells expressing ALDH rose with the increase in CD44+ cells number (R2=0.280, p=0.005). We found a positive correlation between the numbers of CD44+ and CD133+ cells in the tumor parenchyma (r=0.408, p=0.031). Conclusion. Cancer stem cell markers are co-expressed in primary tumor tissue in OC. The expression of stem markers differs depending on the histological subtype and the presence of prior exposure to chemotherapy. Keywords: tumor stem cells, ovarian cancer, chemotherapy, CD44, CD133, ALDH, immunohistochemistry