Gastroenterology

Gastroenterology

Volume 115, Issue 5, November 1998, Pages 1049-1055
Gastroenterology

Rapid Communication
Activation of PPARγ leads to inhibition of anchorage-independent growth of human colorectal cancer cells,☆☆,

https://doi.org/10.1016/S0016-5085(98)70072-1Get rights and content

Abstract

Background & Aims: Peroxisomal proliferator–activated receptor γ (PPARγ) is a nuclear hormone receptor that provides a direct link between fatty acid metabolism and control of gene transcription. The objective of this study was to determine the biological effect(s) of PPARγ activation in colorectal carcinoma cells. Methods: PPARγ expression and activity were measured in 4 human colon cancer cell lines using reverse-transcription polymerase chain reaction, immunoprecipitation and immunoblotting, and transient reporter gene assays. The effects of activated PPARγ in these cell lines were assessed in cellular proliferation and anchorage-independent growth assays. Flow cytometry was used to determine the effects of PPARγ activation on progression through the cell cycle. Results: PPARγ was expressed in all 4 colon cancer cell lines examined and was transcriptionally functional in 3 of the 4. Treatment of these cells with a selective PPARγ activator (BRL 49653) resulted in inhibition of anchorage-independent growth. The degree of growth inhibition correlated with the level of functional PPARγ present. Finally, activation of PPARγ resulted in G1 cell cycle arrest. Conclusions: Activation of the PPARγ pathway in colon cancer cells has potent antiproliferative effects, suggesting that this nuclear hormone receptor may provide a novel target for prevention and treatment of colorectal cancer in humans.

GASTROENTEROLOGY 1998;115:1049-1055

Section snippets

Cell culture

Caco-2, HCT-15, and HCT-116 cells were purchased from American Type Culture Collection (Rockville, MD). HCA-7 cells were a kind gift of Susan Kirkland (University of London).16 Cell lines were grown in Dulbecco's modified Eagle medium (DMEM; GIBCO-BRL, Gaithersburg, MD) supplemented with 10% fetal bovine serum (FBS; Hyclone, Logan, UT), L-glutamine (2 mmol/L), penicillin (100 U/mL), and streptomycin (100 μg/mL) in a 5% CO2 atmosphere with constant humidity.

Stable cell lines

Murine PPARγ 1 complementary DNA

Results and discussion

We selected 4 colon cancer cell lines (HCA-7, HCT-15, HCT-116, and Caco-2) to assess PPARγ expression and endogenous activity. PPARγ mRNA (Figure 1A) and protein (Figure 1B) are present in all 4 cell lines.

. PPARγ is expressed and functionally active in colon cancer cells. (A) PPARγ is expressed at the mRNA level in colon cancer cells. Total RNA (10 μg) from either HCA-7, HCT-15, HCT-116, or Caco-2 cells was subjected to an RT reaction either with (+) or without (−) reverse transcriptase. A 2-μL

Acknowledgements

The authors thank Ron Evans for providing the PPARγ expression vector and the PPRE3-tk-luciferase vector; J. K. Reddy for providing the PPARα expression vector; G. A. Rodan for providing the PPARβ expression vector; and Glaxo Welcome for providing BRL 49653.

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Address requests for reprints to: Raymond DuBois, M.D., Ph.D., Department of Medicine/GI, MCN C-2104, Vanderbilt University Medical Center, Nashville, Tennessee 37232-2279. Fax: (615) 343-6229.

☆☆

Supported by U.S. Public Health Services grants DK-47297 to (R.N.D.), NIEHS-00267, and a Veterans Administration Merit Grant to (R.N.D.).

Dr. DuBois is the Mina Cobb Wallace Professor of Gastroenterology and Cancer Prevention at Vanderbilt University Medical Center.

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