[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.


CONCLUSIONS
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.
Zhang
Min
M
Department of Hematology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
Zou
Ping
P
Bai
Ming
M
Tao
Xiao-nan
XN
Jin
Yang
Y
Guo
Rong
R
D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D020287:In Situ Nick-End Labeling; D015230:Prostaglandin D2 / Q000031:analogs & derivatives* / Q000494:pharmacology; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000819:agonists / Q000235:genetics / Q000378:metabolism*; D045162:Thiazolidinediones / Q000494:pharmacology; D013997:Time Factors; D014157:Transcription Factors / Q000819:agonists / Q000235:genetics / Q000378:metabolism*; D051028:bcl-2-Associated X Protein
C477819:15-deoxyprostaglandin J2; C494826:BAX protein, human; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D045162:Thiazolidinediones; D014157:Transcription Factors; D051028:bcl-2-Associated X Protein; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D015230:Prostaglandin D2; C039671:ciglitazone