TACSTD2
Protein-coding gene in the species Homo sapiens
Tumor-associated calcium signal transducer 2 (Trop-2) is a protein that is encoded by the TACSTD2 gene. The protein was identified via the monoclonal antibody GA733 (giving the name GA733-1). It was separately characterized as an epithelial cell-surface antigen (EGP-1) that was later recognized as a calcium signal transducer (TACSTD2/Trop-2).
This intronless gene is located at the short arm of chromosome 1 (1p32.1). It encodes a carcinoma-associated antigen that is closely related to epithelial cell adhesion molecule (EpCAM/TACSTD1). It transduces an intracellular calcium signal and acts as a cell surface receptor.
It is expressed in low levels in normal epithelia but is overexpressed in the membranes of many epithelial-derived cancers, including breast (especially triple-negative breast cancer), lung, gastric, colorectal, pancreatic, and ovarian, cancers. High expression of TACSTD2 in cancer drives proliferation and is associated with worse outcomes. Mutations of this gene result in gelatinous drop-like corneal dystrophy, an autosomal recessive disorder characterized by severe corneal amyloidosis leading to blindness.
01Tissue distribution
Trop-2 expression was originally described in trophoblasts (placenta) and fetal tissues (e.g., lung). Later, its expression was described in the normal stratified squamous epithelium of the skin, uterine cervix, esophagus, and tonsillar crypts.
02Function
Trop-2 plays a role in tumor progression by interacting with molecular signaling pathways traditionally associated with cancer development and progression. Aberrant overexpression of Trop-2 has been described in several solid cancers, such as colorectal, renal, lung, and breast cancers. Trop-2 expression has been described in some rare and aggressive malignancies, e.g., salivary duct, anaplastic thyroid, uterine/ovarian, and neuroendocrine prostate cancers. This overexpression is caused by deregulation at a transcriptional and posttranscriptional level.
03Clinical significance
Cancer
Trop-2 causes cancer cell growth, proliferation, invasion, migration, and survival of cancer cells. Trop-2 is associated with tumor aggressiveness and poor prognosis. Tumor cell proliferation is disturbed when Trop-2 is knocked down. Trop-2 is a possible prognostic biomarker to identify high-risk patients, as well as an attractive therapeutic target for late-stage disease.
Therapeutics
This antigen is the target of antibody-drug conjugates including sacituzumab govitecan, datopotamab deruxtecan (Dato-DXd), and sacituzumab tirumotecan. In May 2026, Merck announced that its Phase 3 sacituzumab tirumotecan TroFuse-005 trial met both primary endpoints (overall survival + progression-free survival) in patients with advanced or recurrent endometrial cancer who had progressed after platinum chemotherapy and immunotherapy. it has Breakthrough Therapy Designation for EGFR-mutated NSCLC.
Sources and credits
This article is adapted from the Wikipedia article “TACSTD2”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.
Images, from Wikimedia Commons:
- TACSTD2.png by Goultard59, CC BY-SA 4.0
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