Induction of differentiation and peroxisome proliferator-activated receptor gamma expression in colon cancer cell lines by troglitazone.
OBJECTIVE
We investigated the relationship between the effects of troglitazone (TGZ) on cellular growth, differentiation and apoptosis induction, and the induction of peroxisome proliferator-activated receptor (PPAR) gamma in three human colon cancer cell lines, HCT-15, DLD-1and LoVo.


METHODS
Viable cell number was evaluated by the Alamar blue assay and apoptotic cell death by TUNEL methods. Expression of PPARgamma mRNA and protein was examined by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot, respectively. The differentiation markers of colonic mucosa, villin and MUC2 mRNAs, were analyzed by real-time RT-PCR.


RESULTS
HCT-15 and DLD-1 cells proliferated rapidly while LoVo cells grew slowly. TGZ dose-dependently inhibited the proliferation of all the cell lines, and also induced apoptotic cell death. High expression of PPARgamma mRNA and protein was demonstrated in DLD-1 and LoVo cells before TGZ treatment. After the treatment, PPARgamma mRNA and protein levels were increased in HCT-15 and LoVo cells. Villin and MUC2 mRNAs were increased by TGZ treatment in HCT-15 cells while villin mRNA was repressed in LoVo cells. Changes in expression of PPARgamma, villin or MUC2 mRNAs were not observed in DLD-1 cells.


CONCLUSIONS
These results suggest that PPARgamma levels are not correlated with the rates of cell proliferation. Differentiation induction by TGZ was only observed in the cell lines with enhanced PPARgamma expression.
Kato
Masashi
M
Second Department of Pathology, Hirosaki University School of Medicine, 5 Zaifu-cho, 036-8562, Japan.
Kusumi
Tomomi
T
Tsuchida
Shigeki
S
Tanaka
Masanori
M
Sasaki
Mutsuo
M
Kudo
Hajime
H
D017209:Apoptosis / Q000187:drug effects; D014408:Biomarkers, Tumor / Q000378:metabolism*; D015153:Blotting, Western; D002352:Carrier Proteins / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects; D045744:Cell Line, Tumor; D002839:Chromans / Q000494:pharmacology*; D003110:Colonic Neoplasms / Q000188:drug therapy* / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000187:drug effects / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D020287:In Situ Nick-End Labeling; D008840:Microfilament Proteins / Q000378:metabolism; D055262:Mucin-2; D009077:Mucins / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D045162:Thiazolidinediones / Q000494:pharmacology*; D014157:Transcription Factors / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D000077288:Troglitazone
D014408:Biomarkers, Tumor; D002352:Carrier Proteins; D002839:Chromans; D004268:DNA-Binding Proteins; C524625:MUC2 protein, human; D008840:Microfilament Proteins; D055262:Mucin-2; D009077:Mucins; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D045162:Thiazolidinediones; D014157:Transcription Factors; C026615:villin; D000077288:Troglitazone