Co-Expression of Stem Cell and Epithelial Mesenchymal Transition Markers in Circulating Tumor Cells of Bladder Cancer Patients

OBJECTIVE: Cancer cells with stemness and epithelial-to-mesenchymal transition (EMT) features display enhanced malignant and metastatic potential. This study aimed to introduce a new methodology developed in order to investigate the co-expression of a stemness (OCT4) and EMT markers on single circulating tumor cells (CTCs) of patients with localized urinary bladder cancer and their potential prognostic prediction value. METHODS AND MATERIALS: Between April 2015 and July 2015, blood samples of 51 consecutive patients diagnosed with high risk bladder cancer (cT(1-3)N(0)M(0)) were prospectively investigated for CTCs. Peripheral blood (5 mL) was drawn before primary transurethral resection. Detection of CTCs was performed using the CanPatrol(TM) system. Nucleic acid probes were used to identify CTCs, and expression levels of epithelial and mesenchymal genes in CTCs were examined by situ hybridization assay. RESULTS: All patients received radical cystectomy with pelvic lymph nodes dissection. CTCs were detected in 44 of 51 (86.3%) patients, respectively. The overall mean number of CTCs was 6.1 (range: 0~29; median: 4). A total of 311 CTCs were detected in PB. High OCT4 expression (OCT4(high)) was detected more frequently in Epi(−)Mes(+) cells (p=0.001). Patients with pathological confirmed muscle-invasive bladder cancer (MIBC) had higher Epi(−)Mes(+) CTCs positive rates (p=0.001) and OCT4(high) CTCs positive rates (p=0.019) than pathological confirmed non muscle-invasive bladder cancer (NMIBC). Regarding co-expression of these markers, Epi(−)Mes(+)/OCT4(high) CTCs were more frequently evident in the MIBC setting (30.4% vs 3.6% of patients, p = 0.016). CONCLUSION: A differential expression pattern for these markers was observed both in NMIBC and MIBC disease. A subgroup of CTCs showed a CTCs expressing high OCT4, along with Mes were more frequently detected in patients with MIBC, suggesting that these cells may prevail during tumor muscle invasion and disease progression.