Differential IL-4/Stat6 activities correlate with differential expression of regulatory genes SOCS-1, SHP-1, and PP2A in colon cancer cells.
OBJECTIVE
To investigate potential differences in the expression of Stat6 regulatory genes that may influence IL-4/Stat6 activities (phenotypes) in colon cancer cells.


METHODS
RT-PCR method was employed to examine the constitutive mRNA expression of Stat6 negative regulators SOCS-1 and SHP-1, and positive regulator PP2A in colon cancer cell lines HT-29 and Caco-2. Stat6 protein expression and nuclear phosphorylation were detected using Western blotting.


RESULTS
Caco-2 cells carrying inactive Stat6(null) phenotype showed normal constitutive expression of Stat6 but decreased phosphorylation of nuclear Stat6 compared with HT-29 cells carrying active Stat6(high) phenotype. Stat6(null) Caco-2 cells expressed increased levels of mRNA and protein of SOCS-1 and SHP-1, and decreased mRNA expression of PPP2CA and PPP2CB, encoding two critical subunits of PP2A.


CONCLUSIONS
Constitutively increased expression of Stat6 negative regulators SOCS-1 and SHP-1, together with decreased expression of positive regulator PP2A, may play a role in forming the inactive Stat6(null) phenotype in colon cancer cells.
Department of Immunology, Tongji Medical College, Huazhong University of Science and Technology, 13 Hangkong Road, 430030, Wuhan, Hubei, China.
Qin
Q
Yuan
Pin Dong
PD
Li
Ben Hui
BH
Li
Xian Zi
XZ
Yang
Shuang Bing
SB
Xu
Xiao Hong
XH
Liu
Fu Xiang
FX
Zhou
Wen Jie
WJ
Zhang
D015153:Blotting, Western; D002467:Cell Nucleus / Q000378:metabolism; D003110:Colonic Neoplasms / Q000235:genetics* / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D006801:Humans; D015847:Interleukin-4 / Q000235:genetics* / Q000378:metabolism; D010641:Phenotype; D010766:Phosphorylation; D054648:Protein Phosphatase 2 / Q000235:genetics* / Q000378:metabolism; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6 / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050800:STAT6 Transcription Factor / Q000235:genetics* / Q000378:metabolism; D000071222:Suppressor of Cytokine Signaling 1 Protein; D050826:Suppressor of Cytokine Signaling Proteins / Q000235:genetics* / Q000378:metabolism; D014407:Tumor Cells, Cultured
C508598:IL4 protein, human; D012333:RNA, Messenger; C108944:SOCS1 protein, human; D050800:STAT6 Transcription Factor; C494101:STAT6 protein, human; D000071222:Suppressor of Cytokine Signaling 1 Protein; D050826:Suppressor of Cytokine Signaling Proteins; D015847:Interleukin-4; C517189:PPP2CA protein, human; C517190:PPP2CB protein, human; D054648:Protein Phosphatase 2; C509249:PTPN6 protein, human; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6