Fig. 3

Penfluridol triggers an apoptotic effect via induction of the protein phosphatase 2A (PP2A)-modulated deactivation of mitogen-activated protein kinase (MAPK) pathways. a and b Phosphorylation levels of Akt, ERK1/2, JNK1/2, and p38 were assessed using a Western blot analysis after treatment of Fms-like tyrosine kinase 3 (FLT3)-wild type (WT) acute myeloid leukemia (AML) cells, U937 and HL-60, (a) or FLT3 mutant (internal tandem duplication) cells, MV4–11, (b) with 7.5 μM penfluridol for the indicated time points. c U937 and HL-60 cells were pretreated with and without 20 μM U0126, SP600125, or 1 μM SB203580 for 1 h followed by 7.5 μM penfluridol treatment for an additional 8 h. Expression levels of cleaved poly (ADP ribose) polymerase (PARP) and phosphorylation levels of ERK1/2, JNK1/2, and p38 were determined by a Western blot analysis. d HL-60, U937, and MV4–11 cells were treated with penfluridol (5 or 7.5 μM) or FTY720 (5 μM) for 24 h and phosphorylation levels of PP2A-Cα were determined by a Western blot analysis. e and f Pretreatment of MV4–11 and HL-60 cells with different concentration of okadaic acid (OA) for 1 h followed by 7.5 μM penfluridol treatment for an additional 8 h and the phosphorylation levels of ERK and JNK (e), and cleaved caspase-3 (f) were determined by a Western blot analysis. g Kaplan-Meier plots for high versus low PP2A-C RNA expression in AML. A low PP2A-C RNA expression level was correlated with a poor prognosis in RNA sequencing analysis from the Gene Expression Omnibus (GEO) database (GSE10358) (p = 0.026). h Survival analysis of RNA microarray or RNA sequencing data from the SurvExpress database was assessed in six cohorts, results showed that PP2A-C is a significant prognostic predictive indicator for AML, and patients with high PP2A-C expression had favorable prognoses. The horizontal lines indicate the confidence intervals (CIs)