A rapid in vivo screen for pancreatic ductal adenocarcinoma therapeutics

Authors

Ozhan Ocal, UT Southwestern Medical Center
Victor Pashkov, UT Southwestern Medical Center
Rahul K. Kollipara, UT Southwestern Medical Center
Yalda Zolghadri, UT Southwestern University Medical Center, Shiraz University
Victoria H. Cruz, UT Southwestern University Medical Center
Michael A. Hale, UT Southwestern University Medical Center
Blake R. Heath, UT Southwestern University Medical Center
Alex B. Artyukhin, Virginia Commonwealth University
Alana L. Christie, UT Southwestern University Medical Center
Pantelis Tsoulfas, University of Miami
James B. Lorens, University of Bergen
Galvin H. Swift, UT Southwestern University Medical Center
Rolf A. Brekken, UT Southwestern University Medical Center
Thomas M. Wilkie, UT Southwestern University Medical CenterFollow

Document Type

Article

Original Publication Date

2015

Journal/Book/Conference Title

Disease Models & Mechanisms

Volume

8

Issue

10

DOI of Original Publication

10.1242/dmm.020933

Comments

Originally published at http://dx.doi.org/10.1242/dmm.020933

Date of Submission

November 2015

Abstract

Pancreatic ductal adenocarcinoma (PDA) is the fourth leading cause of cancer-related deaths in the United States, and is projected to be second by 2025. It has the worst survival rate among all major cancers. Two pressing needs for extending life expectancy of affected individuals are the development of new approaches to identify improved therapeutics, addressed herein, and the identification of early markers. PDA advances through a complex series of intercellular and physiological interactions that drive cancer progression in response to organ stress, organ failure, malnutrition, and infiltrating immune and stromal cells. Candidate drugs identified in organ culture or cell-based screens must be validated in preclinical models such as KIC (p48Cre;LSL-KrasG12D;Cdkn2af/f) mice, a genetically engineered model of PDA in which large aggressive tumors develop by 4 weeks of age. We report a rapid, systematic and robust in vivo screen for effective drug combinations to treat Kras-dependent PDA. Kras mutations occur early in tumor progression in over 90% of human PDA cases. Protein kinase and G-protein coupled receptor (GPCR) signaling activates Kras. Regulators of G-protein signaling (RGS) proteins are coincidence detectors that can be induced by multiple inputs to feedback-regulate GPCR signaling. We crossed Rgs16::GFP bacterial artificial chromosome (BAC) transgenic mice withKIC mice and show that the Rgs16::GFP transgene is a KrasG12D-dependent marker of all stages of PDA, and increases proportionally to tumor burden in KIC mice. RNA sequencing (RNA-Seq) analysis of cultured primary PDA cells reveals characteristics of embryonic progenitors of pancreatic ducts and endocrine cells, and extraordinarily high expression of the receptor tyrosine kinase Axl, an emerging cancer drug target. In proof-of-principle drug screens, we find that weanling KIC mice with PDA treated for 2 weeks with gemcitabine (with or without Abraxane) plus inhibitors of Axl signaling (warfarin and BGB324) have fewer tumor initiation sites and reduced tumor size compared with the standard-of-care treatment. Rgs16::GFP is therefore an in vivo reporter of PDA progression and sensitivity to new chemotherapeutic drug regimens such as Axl-targeted agents. This screening strategy can potentially be applied to identify improved therapeutics for other cancers.

Rights

Copyright © 2015. Published by The Company of Biologists Ltd This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution and reproduction in any medium provided that the original work is properly attributed.

Is Part Of

VCU Physiology and Biophysics Publications