Prognostic value of cancer stem cells, epithelial-mesenchymal transition and circulating tumor cells in lung cancer

The epithelial-mesenchymal transition (EMT) is a program involved in embryonic development that is often activated during cancer invasion and metastasis. CD133 is the main marker identifying cancer stem cells (CSCs) in lung cancer. Circulating tumor cells (CTCs) are demonstrated to be useful as a biomarker for the diagnosis and treatment of cancer. The aim of this study was to correlate EMT, CSCs and CTCs with patient prognosis to verify whether they can contribute to better stratification of lung cancer patients at risk for recurrent and metastatic disease. Pulmonary venous blood was drawn after major pulmonary surgery in 45 patients with resectable non-small cell lung cancer (NSCLC) in order to identify CTCs. For the same patients, we also constructed prognostic lung tissue microarrays (TMA) for CD133 and c-kit and evaluated CSC and EMT markers using flow cytometry. Cytokeratin-positive cells were detectable in 11 (23.9%) cases. c-kit expression was heterogeneous in prognostic TMAs while CD133 expression was low or absent which was also confirmed by flow cytometry and RT-PCR. Flow cytometric analysis showed that the mean percentage of cells with CD133 expression was 1.6%. CD90 and CD326 markers were co-expressed with a mean percentage of 10.41%. When CD133 and CD90/CD326 expression was correlated with follow-up, CD133 showed a higher correlation with deceased patients when compared with CD90/CD326 co-expression (32.5 vs. 9.5%). CD133 expression demonstrated a strong significant association with patients exhibiting progressive disease when compared to CD90/CD326 expression (15 vs. 7.1%). CD133 may be significantly associated with invasion and metastatic spread of NSCLC. The co-expression of CD90, CD326 and CD133 has definite prognostic value in patients with NSCLC.