活化的过氧化物酶体增生物激活受体-γ诱导人类肺癌细胞凋亡及其机制的研究

目的 探讨配体活化的过氧化物酶体增生物激活受体(PPAR)-γ对人肺癌细胞生长的影响及其机制。方法 以逆转录聚合酶链反应和Western印迹法分别检测肺癌细胞系上PPAR-γ的表达,以四甲基偶氮唑盐微量酶反应比色(MTT)法检测经PPAR-γ的配体作用后的细胞增殖情况,以TUNEL检测PPAR-γ的配体作用后的细胞凋亡情况,以原位杂交和免疫组化检测处理前后bax和bcl-2的mRNA和蛋白质水平的变化,并以免疫组化检测处理前后细胞半胱氨蛋白水解酶-3的表达情况。结果 肺癌细胞系上有PPAR-γ的表达,经配体活化后能明显抑制细胞生长,且与时间和剂量有关;配体活化后的PPAR-γ能诱导细胞凋亡,且半胱氨蛋白水解酶-3与bax、bcl-2在诱导凋亡前后均有增加,与凋亡程度呈正相关,但bax／bcl-2比值在凋亡前后亦增加。结论 PPAR-γ经配体活化后能通过诱导凋亡而抑制肺癌细胞的生长,且bax／bcl-2的比值与半胱氨蛋白水解酶-3在此过程中起作用,因此该受体在肺癌的发病及进展中起重要作用,有可能成为未来肺癌治疗的新靶点。

Apoptosis of human lung cancer cells induced by activated peroxisome proliferator-activated receptor-gamma and its mechanism

OBJECTIVE: To explore the effects of peroxisome proliferator-activated receptor-gamma (PPAR-gamma) on the growth of human lung cancer cell lines and its possible mechanism. METHODS: Human non-small cell lung cancer (NSCLC) cells of the A549 line and human small cell lung cancer (SCLC) of the LTEP-P line were cultured and were divided into 3 groups respectively: control group, 15d-PGJ(2) group (15d-PGJ(2), a PPAR-gamma activator, was added), and ciglitazone group (ciglitazone, am antidiabetic drug, was added). Twenty-four, forty-eight, and seventy-two hours later, nested RT-PCR was used to detect t the expression of PPAR-gamma mRNA, Western blotting technique was used to detect the expression of PPAR-gamma protein, MTT staining was used to observe the proliferation of cells induced by PPAR-gamma agonists, TUNEL method was used to observe the apoptosis of cells affected by the ligands of PPAR-gamma, the expressions of bax, and bcl-2 mRN and proteins were examined by in situ hybridization and immunohistochemistry, and the expression of caspase-3 was detected by immunohistochemistry. RESULTS: PPAR-gamma was expressed in the two lung cancer cell lines. The cell proliferation was inhibited by 15d-PGJ(2) and ciglitazone, especially the former, in dose-dependent and time-dependent manners. The apoptosis rates were (1.9 +/- 0.5)%, (9.8 +/- 1.5)%, and (5.6 +/- 1.1)% respectively in the control, 15d-PGJ(2), and ciglitazone groups with a significant difference between ant 2 groups (all P < 0.05). The expression rate of bax were (9,2 +/- 1.5)%, (63 +/- 10)%, and (31 +/- 6)% respectively in the control, 15d-PGJ(2), and ciglitazone groups with a very significant difference between ant 2 groups (all P < 0.01). he expression rate of bcl-2 were (18 +/- 3)%, (36 +/- 9)%, and (33 +/- 7)% respectively in the control, 15d-PGJ(2), and ciglitazone groups with a very significant difference between the control group and any of the agonist-treated groups (all P < 0.01) and without significant difference between the two treated groups. The expression rates of caspase-3 were (6.5 +/- 1.0)%, (65 +/- 11)%, and (40 +/- 7)% respectively in the control, 15d-PGJ(2), and ciglitazone groups with a significant difference between any 2 group (all P < 0.01). The caspase-3 level was positively correlated with the level of apoptosis. CONCLUSION: Activated by ligands, PPAR-gamma remarkably inhibits the growth of human lung cancer cells through inducing apoptosis. Caspase-3 and bax/bcl-2 play a role in this process, PPAR-gamma is so important in the pathogenesis and/or progression of lung cancer that it may be a novel therapeutical target against lung cancer.