Fig. 6: FAM20C mediates invasive growth of RG-like cells in a neuron-rich microenvironment.

a Spatial expression pattern of FAM20C in selected spots of DMG1. b The two tailed Paired Samples Wilcoxon Signed Rank Test comparing the expression of FAM20C between paired tumor core and invasive niches from different samples (n = 10). Boxes indicate quartiles, horizontal bar indicates median, and whiskers indicate range, up to 1.5-fold inter-quartile range. c Kaplan–Meier curves comparing the overall survival between FAM20C high (n = 32) versus low (n = 134) groups in the TCGA-GBM cohort. Curve comparison P value was determined by two tailed Log-rank (Mantel–Cox) test. d Left: Illustration of transwell assay with HPT-hNSCs in growth factor deprived medium in the top well and 10% fetal bovine serum in the bottom well. Middle: representative images of crest violet staining for migrated LacZ, F1, and F2 HPT-hNSCs. Right: Quantification of the OD values of invading cells for each group. n = 3 for each group. P values were determined by Student t-test. Error bars indicate mean ± SEM. e Left: Illustration of transwell assay with HPT-hNSCs in the top well and hNSC-derived neurons (day 40) in the bottom well in growth factor deprived medium. Middle: Representative images of crest violet staining for migrated LacZ (n = 3), F1 (n = 3), and F2 (n = 4) HPT-hNSCs. Right: Quantification of the OD values of invading cells for each group. P values were determined by Student t-test. Error bars indicate mean ± SEM. f Left: representative low-magnification images of whole-mount brain sections from LacZ and F1 group (n = 10 for each group). The LacZ and F1 mice shown in this panel both reached the endstage at around 80 days post HPT-hNSC xenograft. White dashed lines mark the tumor inside the brain parenchyma. Red-dashed lines mark the enlarged lateral ventricles (LV). Right: quantification of mCherry⁺ tumor area inside (n = 3 for LACZ group and n = 5 for F1 group) and outside (n = 3 for each group) the brain parenchyma for each group. P values were determined by Student t-test. Error bars indicate mean ± SEM. g Representative images of immunofluorescence (IF) co-labeling of FAM20C/Human Nuclear Antigen (hNu) in tumor areas inside the brains of LacZ and F1 mice (n = 10 for each group). The dashed line marks the border between the tumor core (T) and tumor-infiltrated brain area (TI). Arrows point to FAM20C/hNu co-labeled tumor cells in TI, arrowheads point to adjacent hNu-negative neurons with small, rounded nuclei. h Left: Representative images of IF co-labeling of mCherry/Ki67 in tumor areas inside and outside the brains of LacZ and F1 mice (n = 10 for each group). V, blood vessel. The dashed line marks the border of the brain stem. Right: the ratio of Ki67⁺mCherry⁺ cells among total mCherry⁺ cells in tumor areas inside (n = 3 for LacZ group, n = 5 for F1 group) and outside (n = 3 for LacZ group, n = 5 for F1 group) the brains of LacZ and F1 mice. P values were determined by Student t-test. Error bars indicate mean ± SEM. Source data for d-h are provided as a Source Data file. Scale bars, 50 μm in d, e, g, h, 1 mm in f.