配体活化的过氧化物酶体增殖物激活受体γ诱导结肠癌细胞凋亡

Activation of Peroxisome Proliferator-Activated Receptor Gamma Induces the Apoptosis in Human Colon Cancer Cells

目的:探讨配体活化的过氧化物酶体增殖物激活受体γ(PPARγ)抑制结肠癌细胞生长,及诱导细胞凋亡的作用。方法:逆转录-聚合酶链反应(RT-PCR)及免疫杂交(Western-blot)法测定PPARγ在SW480和LS174T结肠癌细胞中的表达。MTT法检测PPARγ激动剂15脱氧前列腺素J2(15d-PGJ2)和吡格列酮(Pioglita-zone,PGZ)对结肠癌细胞生长的抑制作用。流式细胞术检测细胞凋亡率,电镜观察凋亡细胞形态。免疫细胞化学法检测凋亡相关分子Fas、bcl-XL蛋白表达的变化。结果:PPARγ在SW480和LS174T结肠癌细胞株中均有表达,15d-PGJ2和PGZ对两种细胞的生长均有抑制作用,并呈剂量依赖效应。15d-PGJ2和PGZ显著诱导结肠癌细胞凋亡率增加(P<0.05或P<0.01),电镜显示凋亡细胞特有的形态学改变。免疫细胞化学结果显示,PPARγ激动剂诱导Fas蛋白表达明显增多(P<0.01),bcl-XL蛋白表达显著降低(P<0.01),该改变与凋亡程度呈正相关。结论:PPARγ经配体活化后,通过诱导凋亡抑制结肠癌细胞增殖,该作用可能与促凋亡基因Fas抗原表达上调以及凋亡抑制基因bcl-XL表达下调相关。

Objective： To study the effect of peroxisome proliferators-activated receptor gamma （PPARy） activators inhibiting the proliferation of colon cancer cells and inducing the cell apoptosis. Methods： The expression of PPARy was detected by reverse transcriptase-polymerase chain reaction （RT-PCR） and Western-blot analysis. MTT colorimetric assay was used to detect the inhibition rate by PPARy agonists, Pioglitazone （PGZ） or 15-deoxy-△^12,14-prostaglandin J2 （15 d-PGJ2 ）. Flow cytometry was used to detect the celt apoptosis. The apoptotic morphological changes were observed using electron transmission microscopy. The expression of Fas and bcl-XL of cells was detected by the method of immunohistochemistry. Results： PPARy was expressed in both SW480 and LS174T colon cancer cells. Treatment with 15 d-PGJ2 or PGZ inhibited the cell growth in a dose-dependent manner. The apoptotie rate of two colon cancer cells were significantly increased by the induction of PPARy activators （P〈0.05 or P〈0.01）. After the treatment of PPAR7 activators, the results of immunohistochemistry showed that the protein expression of Fas in experimental group was significantly increased than in control group （P〈0.01）, while the protein expression of bcl-XL was significantly decreased in the experimental group （P〈0.01）. The change of the expression of Fas and bel-XL, was remarkably related to the apoptosis rate. Conclusion： Activation of PPAR7 inhibited the growth of colon cancer cells may be associated with inducing cell apoptosis. The increased expression of functional Fas antigen and the decreased expression of onco-protein bcl-XL. may involve in the process of PPAR7 activators inducing apoptosis.