Fig. 6: The function of PCBP4 in determining susceptibility to anti-MDK treatment.

a The relative cell viability upon MDK neutralization (5 µg/ml, 4 days) normalized to the viability of the control IgG-treated group for each cell line, along with the mRNA expression levels of the indicated genes in the corresponding cells, is shown. b A volcano plot indicating gene expression features predictive of the anti-MDK antibody response identified by elastic net analysis for their frequency (y-axis) and effect size (x-axis). The red dots represent genes with a frequency of >40 frequency via the bootstrap method. The node size is proportional to the linear correlation between the drug and the gene expression. c Scatter plot showing the linear correlation between PCBP4 expression (y-axis) and viability (x-axis). Darker blue dots indicate higher sensitivity to anti-MDK treatment. d Relative survival upon anti-MDK treatment at the indicated doses (4 days) normalized to the survival of the IgG control group of N586 cells transfected with NT shRNA or two different shPCBP4 constructs. e Sphere areas per sector normalized to those of the IgG control group upon treatment with control IgG or the anti-MDK antibody (5 µg/ml) in N586 cells transfected with NT shRNA and two different shPCBP4 constructs are shown in whisker plots (top). Representative images are presented (bottom). The scale bars represent 100 µm. f Percent survival of anti-MDK-treated (5 µg/ml, 4 days) NT shRNA- or ectopic PCBP4-expressing NCI827 cells normalized to that of the corresponding IgG control-treated cells is shown in the bar graph. g The number of spheres per sector in the control IgG- and anti-MDK antibody-treated groups of NT shRNA- or ectopic PCBP4-expressing NCI827 cells is shown in whisker plots (top). Representative images of tumor spheres are presented (bottom). The scale bars represent 100 µm. *p < 0.05, **p < 0.01, and ***p < 0.001.