Introduction: There is a growing body of evidence that cancer stem cells (CSCs) are responsible for tumor initiation, maintenance of tumor bulk and its metastatic potential. Therapy resistance of lung tumor is thought to be related to CSCs. Unfortunately data on the identifying CSCs are discordant and cannot be used in practice.
Aim: The aim of the study was to develop the method to identify CSCs in lung cancer patients.
Methods: Flow cytometry was applied to identify circulating CSCs in the peripheral blood using anti-CD133 and anti-EpCAM antibodies. Events were collected from the lymphocyte gate on the FSC/SSC dot plot and read on the CD133(+) versus EpCAM (+) dot plot. Additionally, confocal microscopy was used to identify CSCs in lung cancer tissue using anti-CD44 and anti-CD90 antibodies.
Results: So far 10 patients were enrolled to the study. Analysis of peripheral blood revealed the presence of CD133(+) cells (median value 6,3%) in each sample, EpCAM (+) cells in 8/10 samples (median value 0,2%) and CD133(+)EpCAM(+) cells in 9/10 samples (median value 0,1%). In our opinion only the latter population is representative for CSCs. We also identify small number of CD44(+)CD90(+) cells in lung cancer tissue sample by confocal microscopy.
Conclusions: Initially we confirmed the presence of putative CSCs in the circulation of lung cancer patients and in lung tumor sample. This study revealed the utility of flow cytometry and confocal microscopy in identifying lung CSCs.