Effects of gastrin 17 on beta-catenin/Tcf-4 pathway in Colo320WT colon cancer cells.
OBJECTIVE
To explore the effect of gastrin 17 (G17) on beta-catenin/T cell factor-4 (Tcf-4) signaling in colonic cancer cell line Colo320WT.


METHODS
The pCR3.1/GR plasmid, which expresses gastrin receptor, cholecystokinin-2 receptor (CCK-2R), was transfected into a colonic cancer cell line Colo320 by Lipofectamine (TM)2000 and the stably expressing CCK-2R clones were screened by G418. The expression levels of gastrin receptor in the Colo320 and the transfected Colo320WT cell line were assayed by RT-PCR. Colo320WT cells were treated with G17 in a time-dependent manner (0, 1, 6, 12, 24 and 48 h), then with L365,260 (Gastrin(17) receptor blocker) for 30 min, and with G17 again for 12 h or L365,260 for 12 h. Expression levels of beta-catenin in a TX-100 soluble fraction and TX-100 insoluble fraction of Colo320WT cells treated with G17 were detected by co-immuniprecipation and Western blot. Immunocytochemistry was used to examine the distribution of beta-catenin in CoLoWT320 cells. Expression levels of c-myc and cyclin D1 in Colo320WT cells treated with G17 were assayed by Western blot.


RESULTS
Expression levels of beta-catenin in the TX-100 solution fraction decreased apparently in a time-dependent fashion and reached the highest level after G17 treatment for 12 h, while expression levels of beta-catenin in the TX-100 insoluble fraction were just on the contrary. Immunocytochemistry showed that beta-catenin was translocated from the cell membranes into the cytoplasm and nucleus under G17 treatment. Expression levels of c-myc and cyclin D1 in the G17-treated Colo320WT cells were markedly higher compared to the untreated Colo320WT cells. In addition, the aforementioned G17-stimulated responses were blocked by L365,260.


CONCLUSIONS
Gastrin17 activates beta-catenin/Tcf-4 signaling in Colo320WT cells, thereby leading to over-expression of c-myc and cyclin D1.
Cao
Jun
J
Department of Gastroenterology, Renmin Hospital of Wuhan University, Jiefang Road 238, Wuhan 430060, Hubei Province, China.
Yu
Jie-Ping
JP
Liu
Chao-Hong
CH
Zhou
Lan
L
Yu
Hong-Gang
HG
D001483:Base Sequence; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism*; D056741:Cyclin D; D016213:Cyclins / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics; D005755:Gastrins / Q000494:pharmacology*; D006801:Humans; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism; D043887:Receptor, Cholecystokinin B / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D051820:TCF Transcription Factors / Q000378:metabolism*; D058118:Transcription Factor 7-Like 2 Protein; D014162:Transfection; D051176:beta Catenin / Q000378:metabolism*
C495270:CTNNB1 protein, human; D056741:Cyclin D; D016213:Cyclins; D018076:DNA, Complementary; D005755:Gastrins; C489427:MYC protein, human; D016271:Proto-Oncogene Proteins c-myc; D043887:Receptor, Cholecystokinin B; D011994:Recombinant Proteins; D051820:TCF Transcription Factors; C544894:TCF7L2 protein, human; D058118:Transcription Factor 7-Like 2 Protein; D051176:beta Catenin; C013550:gastrin 17