Blockade of Src signaling prevented stemness gene expression and proliferation of patient-derived gastric cancer stem cells.

Objectives: Gastric cancer (GC) is one of the most malignant tumors. Mounting studies highlighted gastric cancer stem cells (GCSCs) were responsible for the failure of treatment due to recurrence and drug resistance of advanced GC. However, targeted therapy against GCSC for improving GC prognosis suffered from lack of suitable models and molecular targets in terms of personalized medicine. To address this issue, two patient-derived GC cell lines SD209 and SD292 with cancer stem cells (CSCs) such as phenotype were isolated for establishing targeted therapy aiming at critical metastatic signaling in GC.

Materials and methods: The primary patient-derived GCSCs were established from parts of GC tissues for characterization of stem cells (SCs) phenotype at both cellular and molecular levels. Western blot and Immunohistochemistry (IHC) were performed for identifying the deregulated signaling in GC tissue. Immunofluorescence was used for analyzing proliferating and SC markers in GCSC attached on fibroblast. Acridine orange and propidium iodide analyses were performed for the survival of GCSC in suspensions.

Results: In the culture environments of both SD209 and SD292, a lot of mesenchymal fibroblasts spread and crowd together on which a lot of cell clumps, suspected as GCSC, were firmly attached. In the IHC analysis, the GCSC stemness genes CD44 and Ep-CAM increased in tumor tissues of SD209, whereas Nanog-1 and octamer-binding transcription factor 3 (OCT-3) increased in that of SD292. By immunofluorescent analysis of a proliferation marker Ki67, the growth of SD209 and SD292 on mesenchymal fibroblasts was found to be reduced by dasatinib, the inhibitor of the Src kinase whose activity was upregulated in tumor tissues of both GCs. Dasatinib also suppressed the expression of Nanog-1 and OCT-3 in SD292 attached on mesenchymal fibroblasts.

Conclusion: This study may provide a base for targeted therapy against GCSCs/GCs progression in future preclinical/clinical settings.