Abstract LB-133: De novo expression of gastrin and CCK-B receptors in cell lines derived from KPC mice
Authors: Smith Jill P. , Wang Shangzi , Weiner Louis , Nadella Sandeep 
Published: July 2017

Background: Animal models to study cancer progression and therapeutics are essential but these animal models are most useful when they resemble human cancers, particularly with respect to inflammation and the immune system in carcinogenesis and therapy. Hence, athymic nude mice bearing human cancer explants are being replaced by genetically modified animal models with intact immune systems. Panc02 cancer cells have been used to create a syngeneic immune competent murine model of pancreatic cancer. However, unlike human pancreatic cancer, Panc02 cells express wild-type KRAS and CCK-A type receptors (rather than CCK-B type receptors). We previously showed that the Pdx1-Cre / LSL-KrasG12D transgenic mice develop de novo CCK-B receptors with PanIN progression. Aim: The goal of this investigation was to examine cell cultures derived from the KrasG12D mice to determine if they are indeed similar to human cancers in regard to in vivo growth properties and expression of gastrin and CCK-B receptors.

Methods: Five different pancreatic cell lines were obtained that had been derived from the KPC mice (KPC1, KPC2) or organoids (MT3-2D, MT4-2D, and MT5-2D) of the KPC mice. RNA was extracted from the cell lines and evaluated for CCK-A and CCK-B receptors and the ligand gastrin. Growth studies were characterized in syngeneic C57BL/6 mice. The effects of CCK receptor blockade with proglumide was evaluated on tumor growth in vivo. Histologic sections were stained with H&E, Trichrome, and a PD-L1 Ab.Results: RT-PCR revealed that the KPC and MT-2D cells no longer express the CCK-A receptor found in normal mouse pancreas but all expressed the CCK-B receptor, characteristic of human pancreatic cancers. Gastrin expression was also detected by RT-PCR in all cells. Subcutaneous tumors grew rapidly to 1000mm3 within 21 days after inoculation of 105 cells. Tumor growth in MT3-2D tumors was significantly inhibited and survival of mice prolonged with the CCK-receptor antagonist proglumide compared to PBS controls (p=0.0048). Tumors showed extensive fibrosis characteristic of the human PDAC microenvironment and all tumors had PD-L1 expression.

Conclusion: These studies show that cell lines developed from PanIN lesions in KRAS mice exhibit phenotypic and genetic characteristics comparable to human pancreatic cancers and therefore are promising models to study the relationship of CCK receptor-mediated biology to the development and therapy of pancreatic cancer. De novo expression of the CCK-B receptor and gastrin from mouse pancreas suggests a possible relationship between CCK receptor signaling and mutant KRAS expression.Supported by NCI CA50633, CA51008, and CA194745

Citation Format: Jill P. Smith, Shangzi Wang, Louis Weiner, Sandeep Nadella. De novo expression of gastrin and CCK-B receptors in cell lines derived from KPC mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr LB-133. doi:10.1158/1538-7445.AM2017-LB-133