Fig. 3

Knockdown of PTK6 inhibits the stemness of CRC cells. A The GSEA result indicates an enrichment of gene sets related to reactome transportional regulation of pluripotent stem cells in PTK6 overexpression CRC tissues. B The correlations of PTK6 with chemoresistance and stemness related genes were detected from the GEO database. C Kaplan–Meier survival curves in CRC patients undergoing chemotherapy with distinct PTK6 expression levels. D The in vitro limiting dilution assay shows the effects of PTK6 on the formation of CSC spheres (mean ± SD, n = 12), likelihood ratio test. E Tumor sphere formation assays indicate that silencing of PTK6 decreases the sphere formation of CSC cells. Scale bar represents 50 μm. The right panel shows the relative fold change of sphere number (mean ± SD, n = 3). F Western blots assays demonstrate the influence of PTK6 on the expression of stem cell markers in CRC cells. G Real-time q-PCR analysis was used to detect the effect of PTK6 on the expression of stem cell markers and chemoresistance related genes in CRC cells (mean ± SD, n = 3). H Co-immunofluorescent staining of PTK6 (red), CD133 (green) and EPCAM (green) in CRC cells. Scale bar represents 5 μm. I Co-immunofluorescent staining of PTK6 (red), CD133 (green) and EPACAM (green) in tumor spheres. Scale bar represents 5 μm. J The number of CD133⁺ or SOX2⁺ cells was evaluated in the control and PTK6 silencing CRC cells by flow cytometry (mean ± SD, n = 3). *P < 0.05, **P < 0.01, ***P < 0.001