Abstract: Objective To explore the feasibility of ganglioside GD2 as a marker for lung cancer stem cells (LCSCs). Methods Cancer stem cells (CSCs) of lung cancer cell lines were enriched by spheroid culturing in vitro; The expression of stemness-related genes and GD3 synthase (GD3S) in LCSCs were detected by RT-qPCR and Western blot; The expression of GD2 and other stemness phenotypes in lung cancer cell line A549 were detected by flow cytometry; Cell proliferation was detected by CCK8 assay; Cell invasion and migration in vitro were examined by Transwell and wound healing assays; The oncogenicity of different subpopulations in cell line A549 was compared with tumor xenograft model. Results CSCs of A549 cell were successfully enriched by and the percentage of GD2⁺ cells was 0.57% in adherent cell, but the percentage of GD2⁺ cells was able to increase to 20.4% after spheroid culturing. In comparison with GD2^- A549 cells, GD2⁺ A549 cells showed significantly enhanced cell proliferation (P＜0.05),invasion (P＜0.05) and migration ability (P＜0.01) in vitro. There was a close association between GD2 and two other LCSCs phenotypes, and the expression level of GD2 was positively correlated with the expression of CD44 (P＜0.01) and EpCAM (P＜0.001). The results in vivo indicated that tumors formed by GD2⁺ A549 cells grew faster (P＜0.001) and were more malignant (P＜0.01) as compared to GD2^- A549 cells. Conclusions Ganglioside GD2 is a potential marker for LCSCs to identify cancer stem cells, providing a novel strategy of GD2-targeted lung cancer immunothearapy.

Key words: lung cancer stem cells, ganglioside GD2, tumor-associated antigen, immunotherapy