Combined evaluation of proliferation and apoptosis to calculate IC₅₀ of VPA-induced PANC-1 cells and assessing its effect on the Wnt signaling pathway.

Abstract

Pancreatic ductal adenocarcinoma (PDAC) is among the most deadly cancers. Since most patients develop resistance to conventional treatments, new approaches are in urgency. Valproic acid (VPA) was shown to induce apoptosis and reduce proliferation in PANC-1 cells. Wnt signaling pathway is known to be involved in apoptosis and PDAC onset. However, VPA-induced apoptosis and its impact on Wnt signaling in PDACs are not linked, yet. We aimed to calculate IC50 of VPA-induced PANC-1 cells by combined analyses of proliferation and apoptosis, while assessing its effect on Wnt signaling pathway. PANC-1 was induced with increased VPA doses and time points. Three independent proliferation and apoptosis assays were performed utilizing carboxyfluorescein succinimidyl ester and Annexin V/PI staining, respectively. Flow cytometry measurements were analyzed by CellQuest and NovoExpress. Taqman hydrolysis probes and SYBR Green PCR Mastermix were assessed in expression analyses of Wnt components utilizing 2(-Delta Delta Ct) method. Cell proliferation was inhibited by 50% at 2.5 mM VPA that evoked a significant apoptotic response. Among the screened Wnt components and target genes, only LEF1 exhibited significant four-fold upregulation at this concentration. In conclusion, cancer studies mostly utilize MTT or BrdU assays in estimating cell proliferation and calculating IC50 of drugs, which provided conflicting VPA dosages utilizing PANC-1 cells. Our novel combined approach enabled specific, accurate and reproducible IC50 calculation at single cell basis with no apparent effect on Wnt signaling components. Future studies are needed to clarify the role of LEF1 in this model.