Trophoblast glycoprotein, also known as TPBG, 5T4, Wnt-Activated Inhibitory Factor 1 or WAIF1, is a human protein encoded by a TPBG gene.[5] TPBG is an antagonist of Wnt/β-catenin signalling pathway.[6]
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5T4 is an antigen expressed in a number of carcinomas.[7] It is an N-glycosylated transmembrane 72 kDa glycoprotein containing eight leucine-rich repeats.[6] 5T4 is often referred to as an oncofetal antigen due to its expression in foetal trophoblast (where it was first discovered) or trophoblast glycoprotein (TPBG).
5T4 is found in tumors including the colorectal, ovarian, and gastric. Its expression is used as a prognostic aid in these cases. It has very limited expression in normal tissue but is widespread in malignant tumours throughout their development. One study found that 5T4 was present in 85% of a cohort of 72 colorectal carcinomas and in 81% of a cohort of 27 gastric carcinomas.[8]
Its confined expression appears to give 5T4 the potential to be a target for T cells in cancer immunotherapy. There has been extensive research into its role in antibody-directed immunotherapy through the use of the high-affinity murine monoclonal antibody, mAb5T4, to deliver response modifiers (such as staphylococcus aureus superantigen) accurately to a tumor.
5T4 is also the target of the cancer vaccine TroVax which is in clinical trials for the treatment of a range of different solid tumour types.
TPBG has been shown to interact with GIPC1.[9]
Starzynska T, Wiechowska-Kozlowska A, Marlicz K, Bromley M, Roberts SA, Lawniczak M, Kolodziej B, Zyluk A, Stern PL (Jun 1998). "5T4 oncofetal antigen in gastric carcinoma and its clinical significance". European Journal of Gastroenterology & Hepatology. 10 (6): 479–84. doi:10.1097/00042737-199806000-00008. PMID 9855063. S2CID 19687036.
Awan A, Lucic MR, Shaw DM, Sheppard F, Westwater C, Lyons SA, Stern PL (Jan 2002). "5T4 interacts with TIP-2/GIPC, a PDZ protein, with implications for metastasis". Biochemical and Biophysical Research Communications. 290 (3): 1030–6. doi:10.1006/bbrc.2001.6288. PMID 11798178.
- Carsberg CJ, Myers KA, Evans GS, Allen TD, Stern PL (Aug 1995). "Metastasis-associated 5T4 oncofoetal antigen is concentrated at microvillus projections of the plasma membrane". Journal of Cell Science. 108. 108 (8): 2905–16. doi:10.1242/jcs.108.8.2905. PMID 7593330.
- Myers KA, Rahi-Saund V, Davison MD, Young JA, Cheater AJ, Stern PL (Mar 1994). "Isolation of a cDNA encoding 5T4 oncofetal trophoblast glycoprotein. An antigen associated with metastasis contains leucine-rich repeats". The Journal of Biological Chemistry. 269 (12): 9319–24. doi:10.1016/S0021-9258(17)37110-7. PMID 8132670.
- King KW, Sheppard FC, Westwater C, Stern PL, Myers KA (Jun 1999). "Organisation of the mouse and human 5T4 oncofoetal leucine-rich glycoprotein genes and expression in foetal and adult murine tissues". Biochimica et Biophysica Acta (BBA) - Gene Structure and Expression. 1445 (3): 257–70. doi:10.1016/s0167-4781(99)00055-x. PMID 10366710.
- Awan A, Lucic MR, Shaw DM, Sheppard F, Westwater C, Lyons SA, Stern PL (Jan 2002). "5T4 interacts with TIP-2/GIPC, a PDZ protein, with implications for metastasis". Biochemical and Biophysical Research Communications. 290 (3): 1030–6. doi:10.1006/bbrc.2001.6288. PMID 11798178.
- Shaw DM, Woods AM, Myers KA, Westwater C, Rahi-Saund V, Davies MJ, Renouf DV, Hounsell EF, Stern PL (Apr 2002). "Glycosylation and epitope mapping of the 5T4 glycoprotein oncofoetal antigen". The Biochemical Journal. 363 (Pt 1): 137–45. doi:10.1042/0264-6021:3630137. PMC 1222460. PMID 11903056.
- Otsuki T, Ota T, Nishikawa T, Hayashi K, Suzuki Y, Yamamoto J, Wakamatsu A, Kimura K, Sakamoto K, Hatano N, Kawai Y, Ishii S, Saito K, Kojima S, Sugiyama T, Ono T, Okano K, Yoshikawa Y, Aotsuka S, Sasaki N, Hattori A, Okumura K, Nagai K, Sugano S, Isogai T (2007). "Signal sequence and keyword trap in silico for selection of full-length human cDNAs encoding secretion or membrane proteins from oligo-capped cDNA libraries". DNA Research. 12 (2): 117–26. doi:10.1093/dnares/12.2.117. PMID 16303743.
- Ward CM, Eastham AM, Stern PL (Jun 2006). "Cell surface 5T4 antigen is transiently upregulated during early human embryonic stem cell differentiation: effect of 5T4 phenotype on neural lineage formation". Experimental Cell Research. 312 (10): 1713–26. doi:10.1016/j.yexcr.2006.02.006. PMID 16616918.
- Smyth LJ, Elkord E, Taher TE, Jiang HR, Burt DJ, Clayton A, van Veelen PA, de Ru A, Ossendorp F, Melief CJ, Drijfhout JW, Dermime S, Hawkins RE, Stern PL (Oct 2006). "CD8 T-cell recognition of human 5T4 oncofetal antigen". International Journal of Cancer. 119 (7): 1638–47. doi:10.1002/ijc.22018. PMID 16646078. S2CID 12989205.
- Okazaki S, Sekizawa A, Purwosunu Y, Farina A, Wibowo N, Okai T (Nov 2007). "Placenta-derived, cellular messenger RNA expression in the maternal blood of preeclamptic women". Obstetrics and Gynecology. 110 (5): 1130–6. doi:10.1097/01.AOG.0000286761.11436.67. PMID 17978129. S2CID 24566450.