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Functional characterization of peroxisome proliferator‐activated receptor‐β/δ expression in colon cancer
Author(s) -
Foreman Jennifer E.,
Chang WenChi L.,
Palkar Prajakta S.,
Zhu Bokai,
Borland Michael G.,
Williams Jennie L.,
Kramer Lance R.,
Clapper Margie L.,
Gonzalez Frank J.,
Peters Jeffrey M.
Publication year - 2011
Publication title -
molecular carcinogenesis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.254
H-Index - 97
eISSN - 1098-2744
pISSN - 0899-1987
DOI - 10.1002/mc.20757
Subject(s) - biology , peroxisome proliferator activated receptor , apoptosis , cancer research , colorectal cancer , receptor , poly adp ribose polymerase , cancer , microbiology and biotechnology , biochemistry , polymerase , enzyme , genetics
This study critically examined the role of PPARβ/δ in colon cancer models. Expression of PPARβ/δ mRNA and protein was lower and expression of CYCLIN D1 protein higher in human colon adenocarcinomas compared to matched non‐transformed tissue. Similar results were observed in colon tumors from Apc +/Min‐FCCC mice compared to control tissue. Dietary administration of sulindac to Apc +/Min‐FCCC mice had no influence on expression of PPARβ/δ in normal colon tissue or colon tumors. Cleaved poly (ADP‐ribose) polymerase (PARP) was either increased or unchanged, while expression of 14‐3‐3ε was not influenced in human colon cancer cell lines cultured with the PPARβ/δ ligand GW0742 under conditions known to increase apoptosis. While DLD1 cells exhibited fewer early apoptotic cells after ligand activation of PPARβ/δ following treatment with hydrogen peroxide, this change was associated with an increase in late apoptotic/necrotic cells, but not an increase in viable cells. Stable over‐expression of PPARβ/δ in human colon cancer cell lines enhanced ligand activation of PPARβ/δ and inhibition of clonogenicity in HT29 cells. These studies are the most quantitative to date to demonstrate that expression of PPARβ/δ is lower in human and Apc +/Min‐FCCC mouse colon tumors than in corresponding normal tissue, consistent with the finding that increasing expression and activation of PPARβ/δ in human colon cancer cell lines inhibits clonogenicity. Because ligand‐induced attenuation of early apoptosis can be associated with more late, apoptotic/necrotic cells, but not more viable cells, these studies illustrate why more comprehensive analysis of PPARβ/δ‐dependent modulation of apoptosis is required in the future. © 2011 Wiley Periodicals, Inc.