Enzymatic tissue disintegration leads to the loss of immunophenotype of breast cancer stem cells.

Abstract

e13089 Background: Cancer stem cells (CSC) are a population in the complex hierarchy of tumor tissue responsible for growth, metastasis and resistance to chemotherapy and radiotherapy. The purpose of the study was to reveal the effect of the enzymatic disintegration of breast cancer (BC) tissue on the CSC immunophenotype. Methods: BC tumor samples obtained during surgery were placed for 2 hours in a sterile Hanks’ solution immediately after collection. Samples were fragmented to 1 mm in diameter, the fragments were evenly distributed into 4 Petri dishes with (6 cm diameter) and placed in DMEM medium (Gibco, USA) without collagenase and with the addition of collagenase (Biolot, Russia) to a final concentration of 150, 300 and 450 units/ml. Samples were cultured for 48 hours at 37°C and 5.5% CO2. On day 2, the samples incubated in collagenase were grinded by passing through tips of decreasing diameter; the reference sample was grinded in the Medimachine system (BD, USA). The effect of enzymatic tissue disintegration on the preservation of BC SC immunophenotype (CD24low/-CD44+) was evaluated using the BD FacsCanto II flow cytometer (BD, USA) and PE Mouse Anti-Human CD24 (clone ML5; BD, USA) and FITC Mouse Anti-Human CD44 (clone G44-26; BD, USA) antibodies. Results: The total number of isolated cells increased almost exponentially with increasing collagenase concentration. The trypan blue test showed that cell viability did not change significantly with an increase in collagenase concentration and was approximately 50%, being an order of magnitude higher compared to mechanical dissociation (4%). However, 48 h incubation in a collagenase solution led decreased the number of CD44+ cells in proportion to the enzyme concentration by 3 to 10 times in comparison with the control. Similarly, inhibition of CD24 expression was observed compared with the control, inevitably leading to a decreased purity of the isolated subpopulation with the CD24low/-CD44+ phenotype. Conclusions: Despite an increase in the yield of viable cells, prolonged incubation in a collagenase solution leads to a loss of the immunophenotype of BC SC.