Researchers identified Tumor-associated glycoprotein 72 (TAG-72) in the mid-1980s during the development of the Monoclonal antibody B72.3. These antibodies selectively bound to a high-molecular-weight glycoprotein found on various Carcinoma cells. Later studies confirmed TAG-72 as a Mucin-like molecule with significant Glycosylation, which adds to its high molecular weight.[8] This discovery has supported advancements in cancer diagnostics and therapeutics, especially those targeting TAG-72-expressing tumors.[9]
Structure
TAG-72 is a high-molecular-weight glycoprotein(>1,000 Kda), primarily expressed on the surface of various Adenocarcinomas. Its structure is features extensive O-linked glycosylation,[9] which gives it a mucin-like configuration.[9][10][8] The glycosylation patterns of TAG-72 include tumor-associated carbohydrate antigens such assialyl-Tn (STn) and Thomsen–Friedenreich antigens, which are contribute to tumor progression and metastasis.[11] These carbohydrate epitopes serve as binding sites for monoclonal antibodies like B72.3 and CC49, enabling targeted cancer detection and treatment.[9]
Pathogenic mechanism
TAG-72 rarely appears in normal adult tissues but is highly present in malignant epithelial cells, which makes it a Tumor-specific antigen.[8] It plays a role in:
Tumor Progression: TAG-72 forms part of the mucinous barrier that shields tumor cells from immune recognition.[12]
Cell Adhesion and Metastasis: Its Glycosylation influences how tumor cells interact with the extracellular matrix, facilitating metastasis.[13]
Clinical applications
1. Tumor Marker (CA 72-4 Assay)
There was a significant difference (p = 0.005) in the proportion surviving between those patients with no residual TAG-72-positive tissue at the end of surgery (red dashed line) as compared to those patients where residual TAG-72-positive tissue (blue dashed line) remained at the end of surgery.
Gastric cancer: CA 72-4, an immunoassay detecting TAG-72, is widely used for diagnosing and monitoring gastric cancer.[25]
Pancreatic cancer: TAG-72 levels have helped in diagnosing late stage pancreatic cancers.[26]
Gynecological
Ovarian cancer: TAG-72 expression correlates with tumor stage and patient prognosis.[27]
Other cancers
Lung cancer: TAG-72 is present in a subset of non-small cell lung carcinomas.[28]
Breast cancer: Although less specific, TAG-72 has been detected in certain aggressive breast cancer subtypes.[29]
References
↑ Ponnusamy MP, Venkatraman G, Singh AP, Chauhan SC, Johansson SL, Jain M, etal. (2007-06-28). "Expression of TAG-72 in ovarian cancer and its correlation with tumor stage and patient prognosis". Cancer Letters. 251 (2): 247–257. doi:10.1016/j.canlet.2006.11.025. PMID17210225.
↑ Sheer DG, Schlom J, Cooper HL (Dec 1988). "Purification and Composition of the Human Tumor-associated Glycoprotein (TAG-72) Defined by Monoclonal Antibodies CC49 and B72.3". Cancer Research. 48 (23): 6811–6818. PMID3180090.
↑ Guadagni F, Roselli M, Amato T, Cosimelli M, Perri P, Casale V, etal. (1992-03-01). "CA 72-4 measurement of tumor-associated glycoprotein 72 (TAG-72) as a serum marker in the management of gastric carcinoma". Cancer Research. 52 (5): 1222–1227. ISSN0008-5472. PMID1737383.
↑ Cho J, Kim KM, Kim HC, Lee WY, Kang WK, Park YS, etal. (January 2019). "The prognostic role of tumor associated glycoprotein 72 (TAG-72) in stage II and III colorectal adenocarcinoma". Pathology, Research and Practice. 215 (1): 171–176. doi:10.1016/j.prp.2018.10.024. ISSN1618-0631. PMID30466765.
↑ Pasquali C, Sperti C, D'Andrea AA, Costantino V, Filipponi C, Pedrazzoli S (June 1994). "Clinical value of serum TAG-72 as a tumor marker for pancreatic carcinoma. Comparison with CA 19-9". International Journal of Pancreatology. 15 (3): 171–177. doi:10.1007/BF02924191. ISSN0169-4197. PMID7930777.
↑ Ponnusamy MP, Venkatraman G, Singh AP, Chauhan SC, Johansson SL, Jain M, etal. (2007-06-28). "Expression of TAG-72 in ovarian cancer and its correlation with tumor stage and patient prognosis". Cancer Letters. 251 (2): 247–257. doi:10.1016/j.canlet.2006.11.025. ISSN0304-3835. PMID17210225.
↑ Galietta A, Pizzi C, Pettinato G, Limite G, Sgambato A, Lamberti M, etal. (2002). "Differential TAG-72 epitope expression in breast cancer and lymph node metastases: a marker of a more aggressive phenotype". Oncology Reports. 9 (1): 135–140. ISSN1021-335X. PMID11748471.
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