Fig. 5: STAT1 and STAT3 are constitutively active and growth promoting in ovarian cancer cells.

a Relative mRNA expression levels of primary JAK/STAT family members in normal fallopian tube epithelial cells (FT194, FT282) and ovarian cancer cell lines under normal growth conditions. b Western blots depicting the total protein and phosphorylation levels of primary JAK/STAT signaling components in indicated cell lines under normal growth conditions. Actin and vinculin served as loading controls. c Western blots depicting the levels of STAT1 and STAT3 phosphorylation in response to 10 ng/mL IFNγ and increasing concentrations of lestaurtinib for 30 min. Actin served as the loading control. d Western blots depicting total STAT1 and STAT3 protein following 72 h treatment with scrambled control, STAT1 or STAT3 siRNA. Actin served as the loading control. e Relative cell proliferation rates in response to siRNA-mediated STAT1 or STAT3 knockdown 5 days after transfection. N = 5–10. f Representative brightfield images depicting cell density 5 days post-transfection. g Western blots depicting total STAT1 and STAT3 protein levels in MDAH and OVSAHO parental, STAT1 (S1) and STAT3 (S3) CRISPR knockout (KO) cells. Actin served as the loading control. h Relative proliferation rates of control, STAT1 and STAT3 KO cells and i representative brightfield images depicting cell density 5 days after plating. N = 8–10. j STAT1 and STAT3 essentiality in a panel of 59 ovarian cancer cell lines assessed via RNAi or CRISPR KO screens from the DepMap database. Gene Effect <0 indicates dependency, <-1 indicates essentiality. Abbreviations: Par parental, Cis Res cisplatin resistant, Olap^R olaparib-resistant, Con control, WT wildtype, KO knockout, S1 STAT1, S3 STAT3. Graphs depict mean ± standard error. ANOVA p-values: *<0.0332,**<0.0021,***<0.0002,****<0.0001.