Decreased perioxisome proliferator-activated receptor gamma gene expression was correlated with poor prognosis in patients with lung cancer.
ABSTRACT Activation of the nuclear hormone receptor perioxisome proliferator-activated receptor gamma (PPARgamma) inhibits cell growth and induces apoptosis in several human cancers. We have hypothesized that PPARgamma mRNA levels could be predictors of the differentiation and survival of lung cancer. The study included 77 lung cancer cases. The mRNA levels were quantified by real time reverse transcription-polymerase chain reaction (RT-PCR) using LightCycler. The PPARgamma mRNA levels were decreased in tumor tissues from lung cancer (0.579 +/- 1.255) compared to the normal adjacent lung tissues (4.191 +/- 2.868) (P = 0.0001). No significant difference in PPARgamma mRNA levels was found among gender, age, and pathological subtype. The PPARgamma mRNA levels were higher in tumor tissues from higher differentiated lung cancer. The NSCLC patients with low PPARgamma mRNA expression (< 0.5) had significantly worse survival than the patients without low PPARgamma mRNA levels (P = 0.0438, Breslow-Gehan-Wilcoxon test; P = 0.0168, Cox's proportional-Hazards regression model). Thus, PPARgamma mRNA levels may serve as a prognostic marker in lung cancer. Using the LightCycler RT-PCR assay, the determination of PPARgamma mRNA levels might provide a potential marker for treatment of lung cancer by PPARgamma agonist. However, further studies and a longer follow up are needed to confirm the impact of PPARgamma in the biological behavior of the tumor.
- SourceAvailable from: Kohjiro Ueki[show abstract] [hide abstract]
ABSTRACT: Troglitazone (CS-045) is one of the thiazolidinediones that activate the peroxisome proliferator-activated receptor gamma (PPARgamma), which is expressed primarily in adipose tissues. To elucidate the mechanism by which troglitazone relieves insulin resistance in vivo, we studied its effects on the white adipose tissues of an obese animal model (obese Zucker rat). Administration of troglitazone for 15 d normalized mild hyperglycemia and marked hyperinsulinemia in these rats. Plasma triglyceride level was decreased by troglitazone in both obese and lean rats. Troglitazone did not change the total weight of white adipose tissues but increased the number of small adipocytes (< 2,500 micron2) approximately fourfold in both retroperitoneal and subcutaneous adipose tissues of obese rats. It also decreased the number of large adipocytes (> 5,000 micron2) by approximately 50%. In fact, the percentage of apoptotic nuclei was approximately 2.5-fold higher in the troglitazone-treated retroperitoneal white adipose tissue than control. Concomitantly, troglitazone normalized the expression levels of TNF-alpha which were elevated by 2- and 1.4-fold in the retroperitoneal and mesenteric white adipose tissues of the obese rats, respectively. Troglitazone also caused a dramatic decrease in the expression levels of leptin, which were increased by 4-10-fold in the white adipose tissues of obese rats. These results suggest that the primary action of troglitazone may be to increase the number of small adipocytes in white adipose tissues, presumably via PPARgamma. The increased number of small adipocytes and the decreased number of large adipocytes in white adipose tissues of troglitazone-treated obese rats appear to be an important mechanism by which increased expression levels of TNF-alpha and higher levels of plasma lipids are normalized, leading to alleviation of insulin resistance.Journal of Clinical Investigation 03/1998; 101(6):1354-61. · 12.81 Impact Factor
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ABSTRACT: Peroxisome proliferator-activated receptors (PPARs), members of the nuclear hormone receptors superfamily, have an important regulatory role in adipogenesis and inflammation. PPAR-gamma ligands induce terminal differentiation and growth inhibition of human breast cancer cells and prostatic cancer cells. In this study, we demonstrated that PPAR-gamma, but not PPAR-alpha, was expressed in human lung cancer cell lines by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot analysis. We also found that the synthetic PPAR-gamma agonist thiazolidinedione compounds (troglitazone) and the endogenous PPAR-gamma ligand, 15-deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)), inhibited the growth of human lung cancer cells through the induction of apoptosis. However, PPAR-alpha agonist (bezafibrate) and other prostanoids (PGE(2), PGF(2alpha)) did not induce apoptosis. These findings suggest that PPAR-gamma may play an important role in the pathogenesis of lung cancer and that PPAR-gamma agonist may be useful therapeutic agents in the treatment of human lung cancer.Biochemical and Biophysical Research Communications 05/2000; 270(2):400-5. · 2.41 Impact Factor
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ABSTRACT: PPARgamma is a nuclear receptor that has a dominant regulatory role in differentiation of cells of the adipose lineage, and has recently been shown to be expressed in the colon. We show here that PPARgamma is expressed at high levels in both well- and poorly-differentiated adenocarcinomas, in normal colonic mucosa and in human colon cancer cell lines. Ligand activation of this receptor in colon cancer cells causes a considerable reduction in linear and clonogenic growth, increased expression of carcinoembryonic antigen and the reversal of many gene expression events specifically associated with colon cancer. Transplantable tumors derived from human colon cancer cells show a significant reduction of growth when mice are treated with troglitazone, a PPARgamma ligand. These results indicate that the growth and differentiation of colon cancer cells can be modulated through PPARgamma.Nature Medicine 10/1998; 4(9):1046-52. · 22.86 Impact Factor