Fig. 2: Characterizing the binding affinity of L. plantarum WCF1 toward NPC cells.

a Quantification of the cancer binding capacity of commensal strains using CNE-1 as the binding target. n = 3 cell cultures. (P values vs L. reuteri at 10k seeding number = 0.0053, at 15k seeding number = 0.0193, at 20k seeding number = 0.0013, at 30k seeding number = 0.0085, at 50k seeding number = 3.23 × 10⁻⁶). b Lp localized on (i) CNE-1, (ii) CNE-2, (iii) C666-1, (iv) HK-1, and (v) RPMI2650 cell surfaces and absent on (vi) HNC cells. Blue - mammalian nucleus stained by Hoechst. Green - cell cytoskeleton stained by phalloidin, cell cytoplasm stained against GAPDH (RPMI 2650 cells), or microcilia stained against α-tubulins (HNC cells). Red - Lp expressing mCherry. Scale bar -- 25 μm. c Quantification of Lp-cell binding affinity. The y-axis indicates the fold change in the FITC fluorescence signal, standardized to that of the HNC group. n = 5 experimental replicates. (P values HNC vs CNE-1 = 0.0025, vs CNE-2 = 0.0001, vs C666-1 = 0.0024, vs HK-1 = 3.25 × 10⁻⁶, vs RPMI2650 = 2.27 × 10^–5). d IF staining showing interactions between Lp and (i) T24 bladder, (ii) A549 lung, and (iii) AGS gastric cancer cells. Scale bar -- 25 μm. e Inhibition of Lp-NPC binding by heparin salts in the coculture of Lp and four NPC cell lines. n = 5 experimental replicates. (P values in CNE-1 group 0.1 ug/ml vs control = 0.4144, 1 μg/ml vs control = 0.0021, 10 μg/ml vs control = 0.0001, 100 μg/ml vs control = 0.0004; in CNE-2 group 7.06 × 10^–5, 0.0289, 1.08 × 10^–5, 4.58 × 10^–7; in C666-1 group 0.0016, 0.0054, 0.0499, 0.0038; in HK-1 group 0.0568, 0.0816, 0.0001, 2.45 × 10^–7). f Schematic diagram showing possible competitive inhibition between heparan sulfate and heparin. Error bars indicate the standard error (SEM). All the data are presented as mean values ± SEM. Unpaired two-sided Student’s t tests were performed to determine the statistical significance. *P < 0.05; **P < 0.01; ***P < 0.001. Source data are provided as a Source Data file.