Dataset Information

Topical application of a platelet activating factor receptor agonist suppresses phorbol ester-induced acute and chronic inflammation and has cancer chemopreventive activity in mouse skin.

ABSTRACT: Platelet activating factor (PAF) has long been associated with acute edema and inflammatory responses. PAF acts by binding to a specific G-protein coupled receptor (PAF-R, Ptafr). However, the role of chronic PAF-R activation on sustained inflammatory responses has been largely ignored. We recently demonstrated that mice lacking the PAF-R (Ptafr-/- mice) exhibit increased cutaneous tumorigenesis in response to a two-stage chemical carcinogenesis protocol. Ptafr-/- mice also exhibited increased chronic inflammation in response to phorbol ester application. In this present study, we demonstrate that topical application of the non-hydrolysable PAF mimetic (carbamoyl-PAF (CPAF)), exerts a potent, dose-dependent, and short-lived edema response in WT mice, but not Ptafr -/- mice or mice deficient in c-Kit (c-KitW-sh/W-sh mice). Using an ear inflammation model, co-administration of topical CPAF treatment resulted in a paradoxical decrease in both acute ear thickness changes associated with a single PMA application, as well as the sustained inflammation associated with chronic repetitive PMA applications. Moreover, mice treated topically with CPAF also exhibited a significant reduction in chemical carcinogenesis. The ability of CPAF to suppress acute and chronic inflammatory changes in response to PMA application(s) was PAF-R dependent, as CPAF had no effect on basal or PMA-induced inflammation in Ptafr-/- mice. Moreover, c-Kit appears to be necessary for the anti-inflammatory effects of CPAF, as CPAF had no observable effect in c-KitW-sh/W-sh mice. These data provide additional evidence that PAF-R activation exerts complex immunomodulatory effects in a model of chronic inflammation that is relevant to neoplastic development.

SUBMITTER: Sahu RP

PROVIDER: S-EPMC4222871 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Topical application of a platelet activating factor receptor agonist suppresses phorbol ester-induced acute and chronic inflammation and has cancer chemopreventive activity in mouse skin.

Sahu Ravi P RP Rezania Samin S Ocana Jesus A JA DaSilva-Arnold Sonia C SC Bradish Joshua R JR Richey Justin D JD Warren Simon J SJ Rashid Badri B Travers Jeffrey B JB Konger Raymond L RL

PloS one 20141106 11

Platelet activating factor (PAF) has long been associated with acute edema and inflammatory responses. PAF acts by binding to a specific G-protein coupled receptor (PAF-R, Ptafr). However, the role of chronic PAF-R activation on sustained inflammatory responses has been largely ignored. We recently demonstrated that mice lacking the PAF-R (Ptafr-/- mice) exhibit increased cutaneous tumorigenesis in response to a two-stage chemical carcinogenesis protocol. Ptafr-/- mice also exhibited increased c ...[more]

PMID: 25375862

Similar Datasets

Project description:The heterotrimeric G protein α subunit oncogenes GNAQ or GNA11 carry Q209X or R183X activating mutations and are present with ~90% frequency in human uveal melanomas. Forced expression of GNAQ/11(Q209L) in melanocytes is sufficient to drive metastatic melanoma in immune-compromised mice. No known drugs directly target these oncogenic G proteins. Ric-8A is the molecular chaperone that selectively folds Gαq/i/13 subunits. Targeting Ric-8A serves as a rational, yet unexplored approach to reduce the functional abundance of oncogenic Gαq/11 in order to blunt cancer signaling. Here, using mouse melanocyte cell graft tumorigenesis models, we determined that Ric-8A genetic ablation attenuated the abundance and melanoma-driving potential of Gαq-Q209L. A new conditional Ric-8A(Flox/Flox); Rosa-CreER(+/)(-) mouse strain was derived and used as a tissue source to culture an immortalized, tamoxifen-inducible Ric-8A knockout melanocyte cell line that required 12-O-tetradecanoylphorbol-13-acetate (TPA, phorbol ester) for growth. The cell line failed to grow tumors when grafted into immune-compromised mice regardless of Ric-8A expression. Stable expression of human GNAQ(Q209L), but not GNAQ(WT) in the cell line promoted TPA-independent cell proliferation, and upon cell grafting in mice, the initiation and robust growth of darkly-pigmented melanoma tumors. Deletion of Ric-8A in GNAQ(Q209L) cells restored TPA-dependent growth, reduced Gαq-Q209L below detectable levels and completely mitigated tumorigenesis from primary or secondary cell line grafts. Interestingly, TPA treatment of cultured GNAQ(Q209L) cells or host animals grafted with GNAQ(Q209L) cells also sharply reduced Gαq-Q209L abundance and tumorigenic capacity. Finally, tumorigenesis initiated from GNAQ(Q209L) cell grafts, followed by host mouse systemic tamoxifen treatment to delete Ric-8A in the grafted cells completely abrogated GNAQ(Q209L)-driven tumor progression unless a stable human RIC-8A transgene was used to rescue the floxed Ric-8A alleles. Our work defines two new rational targets that may be developed as potential uveal melanoma therapies through reduction of Gαq/11-Q209L oncoprotein abundance: (1) Ric-8A inhibition and (2) phorbol ester treatment.

Dataset Information

Topical application of a platelet activating factor receptor agonist suppresses phorbol ester-induced acute and chronic inflammation and has cancer chemopreventive activity in mouse skin.

Publications

Topical application of a platelet activating factor receptor agonist suppresses phorbol ester-induced acute and chronic inflammation and has cancer chemopreventive activity in mouse skin.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets