Fig. 2.

NNI patient-derived glioblastoma (GBM) cells stratified by their STAT3 status show variable response to signal transducers and activators of transcription 3 (STAT3) inhibitors. a Immunoblot analysis of patient GPCs. STAT3-high cell lines showed elevated phospho-STAT3, compared to STAT3-low cell lines. b–d Patient GBM cells were treated with b AZD1480, c Stattic, and d WP1066, and their IC₅₀ values were determined (results are mean of triplicate experiments). Consistent with bioinformatical prediction, STAT3-high cell lines showed sensitivity to STAT3 inhibitors as demonstrated by lower IC₅₀ values. STAT3-high and -low cell lines were validated by e–g cell viability and h–j clonogenic capacity after treatment with STAT3 inhibitors. STAT3-low cells demonstrated greater viability and gliomasphere-forming capability after treatment with e, h AZD1480, f, i Stattic, and g, j WP1066. Conversely, STAT3-high lines displayed greater sensitivity to STAT3 inhibitors, resulting in reduced cell viability and gliomasphere-forming capability. k–m Recovery assay after 5-day AZD1480 treatment, and the k viability and l clonogenic capacity of STAT3-high GPCs were significantly mitigated. In contrast, STAT3-low GPCs developed resistance and m demonstrated greater ability to invade. *p < 0.05; **p < 0.01; ***p < 0.001; STAT3-high versus STAT3-low. For statistical analysis, two-sided Student’s t test was used. Error bars represent standard deviation of the mean. All results are mean of triplicate experiments. n Orthotopic tumors established from STAT3-high, AZD1480-pretreated cells resulted in mice with prolonged survival. STAT3-high (47 days) patient-derived xenograft demonstrated greater median survival difference of ~2.5-fold for AZD1480 arm compared to o NNI-20 (19 days) animal groups. *p < 0.05; ***p < 0.001 versus dimethyl sulfoxide. For statistical analysis, logrank test was used