A Novel Inhibitor of Epithelial‐to‐Mesenchymal Transition Reduces Pancreatic Cancer Cell Invasion and Tumor Growth in Mice

Abstract

ObjectiveEpithelial to Mesenchymal Transition (EMT) has been proposed to contribute importantly to metastasis, cancer stem cell (CSC) generation and drug resistance in many cancers. Targeting EMT may be promising to benefit cancer treatment. Our previous high throughput screening study has identified a potential EMT inhibitor (namely, C150) in pancreatic cancer cells. Here, we sought to investigate the activities of C150 in inhibiting pancreatic cancer cell invasion, migration and tumor growth in mice, as well as its mechanisms of EMT inhibition.MethodsCell viability was detected by MTT assay. Cell migration/invasion was detected by Boyden chamber trans‐well migration‐invasion assay, wound scratch assay and a 3‐dimension (3D) cell invasion assay. MMP zymography assay was used to indicate MMP inhibition. In vivo tumor growth was evaluated in an orthotopic mouse model of pancreatic cancer. EMT marker proteins were examined by western blot.ResultsC150 exhibited a well‐separated cytotoxicity between pancreatic cancer cells and non‐cancerous cells, with IC50 values of 1~2.5 μM in multiple pancreatic cancer cell lines and >25 μM in a noncancerous pancreatic epithelial cell line (hTERT‐HPNE). C150 was found to significantly inhibit PANC‐1 cell invasion in the 3‐dimension (3D) cell invasion model, the wound scratching assay and the Boyden Chamber trans‐well migration‐invasion assay. C150 treatment reduced the expressions of MMP‐2 and MMP‐9 in PANC‐1 cells, and inhibited MMP enzyme activity in zymography assay. In orthotopic pancreatic cancer mouse model, C150 significantly reduced tumor growth at the dose of 15 mg/kg, 3x weekly by IP injection. C150 decreased the mesenchymal markers of N‐cadherin and Snail while increased epithelial markers of ZO‐1 and Claudin‐1. Further studies revealed that C150 treatment significantly increased proteasome activity in the cell without changing the protein expression levels of proteasome subunits.ConclusionThe novel compound C150 inhibited pancreatic cancer cell migration, invasion, and in vivo tumor growth in mice. The compound increased cellular proteasome activity, which enhanced the protein degradation of Snail, resulting in EMT inhibition in the cell. The studies of more detailed mechanisms of C150 induced EMT inhibition and proteasome activation, as well as target identification are currently undergoing.Support or Funding InformationInstitutional Development Award (IDeA) of NIH and State of Kansas Grant # 8P30GM103495, KU Cancer Center Lied Basic Science Grant 2018