The role of tissue transglutaminase (TG2) in regulating the tumour progression of the mouse colon carcinoma CT26.
The multifunctional enzyme tissue transglutaminase (TG2) is reported to both mediate and inhibit tumour progression. To elucidate these different roles of TG2, we established a series of stable-transfected mouse colon carcinoma CT26 cells expressing a catalytically active (wild type) and a transamidating-inactive TG2 (Cys277Ser) mutant. Comparison of the TG2-transfected cells with the empty vector control indicated no differences in cell proliferation, apoptosis and susceptibility to doxorubicin, which correlated with no detectable changes in the activation of the transcription factor NF-κB. TG2-transfected cells showed increased expression of integrin β3, and were more adherent and less migratory on fibronectin than control cells. Direct interaction of TG2 with β3 integrins was demonstrated by immunoprecipitation, suggesting that TG2 acts as a coreceptor for fibronectin with β3 integrins. All cells expressed the same level of TGFβ receptors I and II, but only cells transfected with active TG2 had increased levels of TGFβ1 and matrix-deposited fibronectin, which could be inhibited by TG2 site-directed inhibitors. Moreover, only cells transfected with active TG2 were capable of inhibiting tumour growth when compared to the empty vector controls. We conclude that in this colon carcinoma model increased levels of active TG2 are unfavourable to tumour growth due to their role in activation of TGFβ1 and increased matrix deposition, which in turn favours increased cell adhesion and a lowered migratory and invasive behaviour.
School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham, B47ET, United Kingdom.
Panayiotis
P
Kotsakis
Zhuo
Z
Wang
Russell John
RJ
Collighan
Martin
M
Griffin
D000818:Animals; D017209:Apoptosis / Q000235:genetics; D002448:Cell Adhesion; D045744:Cell Line, Tumor; D002465:Cell Movement; D049109:Cell Proliferation; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000201:enzymology* / Q000473:pathology*; D004317:Doxorubicin / Q000494:pharmacology; D005109:Extracellular Matrix / Q000378:metabolism; D005260:Female; D005353:Fibronectins; D019204:GTP-Binding Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D039641:Integrin beta Chains; D019012:Integrin beta1; D039661:Integrin beta3; D051379:Mice; D008807:Mice, Inbred BALB C; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D053671:Syndecan-4; D053773:Transforming Growth Factor beta1 / Q000378:metabolism; D011503:Transglutaminases / Q000235:genetics / Q000276:immunology / Q000378:metabolism*
D005353:Fibronectins; D039641:Integrin beta Chains; D019012:Integrin beta1; D039661:Integrin beta3; D016328:NF-kappa B; C508306:Sdc4 protein, mouse; D053671:Syndecan-4; D053773:Transforming Growth Factor beta1; C084344:integrin beta5; D004317:Doxorubicin; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011503:Transglutaminases; D019204:GTP-Binding Proteins