title: Mutant K-RAS Promotes Invasion and Metastasis in Pancreatic Cancer Through GTPase Signaling Pathways.
abstract: Pancreatic ductal adenocarcinoma is one of the most aggressive malignancies, characterized by the local invasion into surrounding tissues and early metastasis to distant organs. Oncogenic mutations of the K-RAS gene occur in more than 90% of human pancreatic cancers. The goal of this study was to investigate the functional significance and downstream effectors of mutant K-RAS oncogene in the pancreatic cancer invasion and metastasis. We applied the homologous recombination technique to stably disrupt K-RAS oncogene in the human pancreatic cell line MiaPaCa-2, which carries the mutant K-RAS (G12C) oncogene in both alleles. Using in vitro assays, we found that clones with disrupted mutant K-RAS gene exhibited low RAS activity, reduced growth rates, increased sensitivity to the apoptosis inducing agents, and suppressed motility and invasiveness. In vivo assays showed that clones with decreased RAS activity had reduced tumor formation ability in mouse xenograft model and increased survival rates in the mouse orthotopic pancreatic cancer model. We further examined molecular pathways downstream of mutant K-RAS and identified RhoA GTP activating protein 5, caveolin-1, and RAS-like small GTPase A (RalA) as key effector molecules, which control mutant K-RAS-dependent migration and invasion in MiaPaCa-2 cells. Our study provides rational for targeting RhoA and RalA GTPase signaling pathways for inhibition of pancreatic cancer metastasis.
authors.affiliation: Department of Biochemistry and Molecular Biophysics, Undergraduate Biology Research Program, University of Arizona, Tucson, Arizona, USA.
authors.forename: Julianna
authors.initials: J
authors.lastname: Padavano
authors.affiliation: Cancer Biology Interdisciplinary Program, University of Arizona Cancer Center, Tucson, AZ, USA.
authors.forename: Rebecca S
authors.initials: RS
authors.lastname: Henkhaus
authors.affiliation: University of Arizona Cancer Center, University of Arizona, Tucson, AZ, USA.
authors.forename: Hwudaurw
authors.initials: H
authors.lastname: Chen
authors.affiliation: University of Arizona Cancer Center, University of Arizona, Tucson, AZ, USA.
authors.forename: Bethany A
authors.initials: BA
authors.lastname: Skovan
authors.affiliation: University of Arizona Cancer Center, University of Arizona, Tucson, AZ, USA.
authors.forename: Haiyan
authors.initials: H
authors.lastname: Cui
authors.affiliation: Department of Cellular & Molecular Medicine, University of Arizona, Tucson, AZ, USA.
authors.forename: Natalia A
authors.initials: NA
authors.lastname: Ignatenko
keywords: AKT; RalA GTPase; Rho GTPase activating protein 5; caveolin-1; metastatic pancreatic cancer; mutant K-RAS knockdown