Abstract 811P
Background
Cancer stem cells (CSCs) initiate and support tumor growth. The data on correlations between the stem markers expression and clinical parameters are contradictory in ovarian cancer (OC). We aimed to assess the expression of CD44, CD133 and ALDH in primary OC tissue in relation to clinical features.
Methods
Tumor tissue samples were obtained during the cytoreductive surgery before or after 3 courses of standard platinum-containing chemotherapy (CT). The stem markers expression was assessed immunohistochemically (Autostainer 360 (Thermo Scientific, USA)) using antibodies to CD44 (EPR 1013Y, Abcam), CD133 (AC133, Miltenyi Biotec), ALDH (44/ALDH, BD Transduction Laboratories). Statistical processing included Fisher's exact test, Mann-Whitney U test, Cox proportional hazards model (Statistica 13.0).
Results
The study included 28 patients: 14 (50%) received adjuvant chemotherapy (ACT) and 14 – neoadjuvant (NACT); 18 patients had FIGO stage III, 3 - I, 1 - II and 6 - IV. Twenty tumors were high-grade serous, 4 - undifferentiated, and 4 - clear-cell. ALDH and CD44 were expressed in most of the samples, both in parenchyma and stroma; CD133 was expressed in parenchyma in 12 samples and not expressed in stroma. The numbers of CD44+ (p=0.053) and ALDH+ (p=0.063) cells tended to be decreased in NACT compared with the ACT. Expression of CD44 (p=0.042) and CD133 (p=0.015) was higher in undifferentiated than in high-grade serous tumors. In CD133+ samples, CD44 expression was increased compared with CD133- ones (p=0.027). In the presence of ascites, CD133 expression tended to be decreased (p=0.053). The percentage of CD44+ cells was higher in platinum-sensitive tumors (relapse >6 months after the last CT) (p=0.038). In the multivariate analysis, overall survival increased in the presence of platinum sensitivity (HR 0.17 95% CI 0.04-0.67, p=0.011) and the presence of CD133 expression compared with its absence (HR 0.17 95% CI 0.03-0.89, p=0.036).
Conclusions
Stem markers CD44 and CD133, but not ALDH, have similar expression patterns in OC tissue. The expression of stem markers in our OC cohort was paradoxically associated with a more favorable clinical outcome, which requires further study. This work was supported by the RFBR grant No. 19-315-90011.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Russian Foundation of Basic Research.
Disclosure
All authors have declared no conflicts of interest.