Pharmacological approaches to understanding the role of PDX1 in pancreatic ductal adenocarcinoma: Insights from the chick CAM model

Abstract

Pancreatic ductal adenocarcinoma (PDAC), the most prevalent form of pancreatic cancer, has a 5-year survival rate of 9%. PDX1 is an important transcription factor for embryonic development of the pancreas, pancreatic endocrine lineage differentiation, and maintenance of mature pancreatic β-cells. In PDAC patients, PDX1 expression is downregulated in tumor cells compared to adjacent non-tumoral tissue. On the other hand, a higher PDX1 expression has been shown to improve the overall survival rate in PDAC patients. Therefore, our aim was to analyze the role of PDX1 on the phenotype of PDAC cells. To induce PDX1 expression, PANC-1 cells, derived from a human PDAC tumor, were treated with BRD7552 (a PDX1 inducer). Overexpression of PDX1 was confirmed by Western Blot analysis and no cytotoxic effects were observed by MTT reduction or Trypan Blue exclusion assays. Cell confluence assay and BrdU incorporation assay showed a significant reduction in proliferation rate in treated cells, while no differences were observed on the proportion of Ki67+ and PH3+ cells by immunostaining. In addition, cell cycle analysis by propidium iodide staining followed by flow cytometry showed an arrest in the G1 phase of the cell cycle of treated cells. Additionally, treated cells showed a significant reduction in migration rate. Furthermore, to assess the in ovo effects of BRD7552, treated PANC-1 cells were implanted onto the chorioallantoic membrane (CAM) of chick embryos and tumor size was measured at different time points, revealing a significant reduction in tumor growth of treated cells. Therefore, in this study we observed that a pharmacological induction of PDX1 in PANC-1 cells affects cell cycle, reduces proliferation rate and inhibits migratory potential in vitro. These findings were corroborated in ovo, where PDX1 overexpression diminished tumor growth of PANC-1 cells. In conclusion, the overexpression of PDX1 induced by BRD7552 drives PANC-1 cells to a less proliferative and migratory phenotype.