Abstract B119: Triptolide abrogates expression of the Met and epidermal growth factor receptors in pancreatic cancer

Abstract

Abstract Background: Minnelide, a pro-drug of the Chinese herb triptolide, is currently in Phase I clinical trials against pancreatic cancer. Preclinical studies with Minnelide have demonstrated its efficacy in preventing tumor formation and causing tumor regression in multiple animal models of pancreatic cancer. However, its mechanism of action remains unclear. Pancreatic cancer cells overexpress several receptor tyrosine kinases including the Met and EGF receptors which drive proliferation, migration and invasion of these cells. Here, using human pancreatic cancer cells as well as the KRasG12D; Trp53R172H; Pdx-1 Cre (KPC) animal model, we show the ability of triptolide, or its water soluble pro-drug, Minnelide, to down-regulate the Met and EGF receptors, both in vitro and in vivo. Methods:Pancreatic cancer cells were treated with triptolide for varying times (0-24h) and receptor levels evaluated using western blotting or confocal microscopy. The KPC mouse model recapitulates human disease progression and is therefore the most relevant model for chemotherapeutic drug testing. KPC animals, which spontaneously form pancreatic tumors, were treated with Minnelide for one week and tumors harvested. mRNA expression was analyzed using real time PCR and protein expression assessed by immunohistochemistry. Results: Treatment with triptolide causes an increase in tyrosine phosphorylation at earlier time points (0.5 - 6h), accompanied by an increase in levels of the Met and EGF receptor tyrosine kinases. However, longer treatments (12-24h) resulted in marked decrease in levels of both Met and EGF receptors. Further investigation using tumors from KPC animals treated with Minnelide show a decrease in gene expression of both the Met and EGF receptors compared with tumors from saline injected animals. Furthermore, immunohistochemical analysis of formalin fixed paraffin embedded sections from these tumors show a decrease in levels of the Met receptor. Conclusion: Treatment of cells or KPC pancreatic tumor bearing animals with triptolide or Minnelide leads to decreased expression of the Met and EGF receptor tyrosine kinases. These results lend further insight into the mechanism of action of Minnelide, a pro-drug currently in clinical trials against pancreatic cancer. Citation Format: Veena Sangwan, Kelsey M. Jensen, Vikas Dudeja, Rohit Chugh, Sulagna Banerjee, Selwyn M. Vickers, Morag Park, Ashok K. Saluja. Triptolide abrogates expression of the Met and epidermal growth factor receptors in pancreatic cancer. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Innovations in Research and Treatment; May 18-21, 2014; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2015;75(13 Suppl):Abstract nr B119.