Detyrosinated α-Tubulin, Vimentin and PD-L1 in Circulating Tumor Cells (CTCs) Isolated from Non-Small Cell Lung Cancer (NSCLC) Patients

Upregulation of Vimentin (VIM), alpha-Tubulin (TUB) and Detyrosinated tubulin (GLU) in circulating tumor cells (CTCs) derived from breast cancer patients is related to poor prognosis. In the current study we evaluated for the first time, these cytoskeletal proteins in sixty Non-Small Cell Lung Cancer (NSCLC) patients' CTCs (33 treatment-naïve and 27 pre-treated). Samples were isolated using the ISET platform and stained with a pancytokeratin (CK)/CD45/TUB, CK/GLU/VIM and CK/programmed death ligand 1 (PD-L1) combination of antibodies. Subsequently, slides were analyzed using confocal laser scanning microscopy. CTCs were detected in 86.7% of the patients. CTCs with TUB expression were identified in 65.4% (34/52) of the CK (+)-patients. GLU, VIM and PD-L1 were also evaluated. The frequency of the observed phenotypes was as follow: (CK+/GLU-/VIM-): 35.2%, (CK+/GLU+/VIM+): 63.0%, (CK+/GLU+/VIM-): 16.7%, (CK+/GLU-/VIM+): 72.2%, (CK+/PD-L1-): 75% and (CK+/PD-L1+): 55%. The OS was significantly decreased in patients with high GLU (3.8 vs. 7.9 months; p = 0.018) and/or high VIM (3.2 vs. 7.1 months; p = 0.029) expression in their CTCs. PD-L1 was also related to OS (3.4 vs. 7.21 months; p = 0.035). Moreover, TUB-high and TUB-low expression in CTCs inversely influenced patients' OS as independent prognostic factors (p = 0.041 and p = 0.009). The current study revealed that TUB, GLU, VIM and PD-L1 were overexpressed in CTCs from NSCLC patients. Furthermore, the presence of GLU, VIM-positive and PD-L1 in CTCs is potentially related to patients' outcomes.