Oncogene database

4070

TACSTD2

tumor-associated calcium signal transducer 2;TACSTD2;tumor-associated calcium signal transducer 2

40kD glycoprotein, identified by monoclonal antibody GA733|cell surface glycoprotein TROP2|cell surface glycoprotein Trop-2|epithelial glycoprotein-1|gastrointestinal tumor-associated antigen GA7331|membrane component chromosome 1 surface marker 1|membran

1p32

protein-coding

The cell surface protein Trop-2 is highly expressed in a wide variety of epithelial cancers. In contrast, there is little or no expression of Trop-2 in adult somatic tissue. Because it is a cell surface protein that is selectively expressed in tumor cells, Trop-2 is a potential therapeutic target. However, whether Trop-2 is actively involved in tumorigenesis and whether its targeting for treatment would be effective have not been examined. Here, we show that Trop-2 expression is necessary for tumorigenesis and invasiveness of colon cancer cells, as both are inhibited when Trop-2 expression is suppressed by RNA interference. Conversely, ectopic expression of Trop-2 in colon cancer cells enhances their capacity for anchorage-independent growth and ectopic expression of Trop-2 in NIH3T3 cells is sufficient to promote both anchorage-independent growth and tumorigenesis. Importantly, we show that an antibody against the extracellular domain of Trop-2 reduces tumor cell invasiveness. Therefore, we have identified Trop-2 as an oncogene that has potential as a therapeutic target. Given the restricted expression of Trop-2 in normal tissue, anti-Trop-2 therapeutics would be predicted to have limited toxicity.

The factors regulating growth of the developing lung are poorly understood, although the degree of fetal lung expansion is critical. The oncogene Trop2 (trophoblast antigen 2) is upregulated during accelerated fetal lung growth, and we hypothesized that it may regulate normal fetal lung growth. We investigated Trop2 expression in the fetal and neonatal sheep lung during accelerated and delayed lung growth induced by alterations in fetal lung expansion, as well as in response to glucocorticoids. Trop2 expression was measured using real-time PCR and localized spatially using in situ hybridization and immunofluorescence. During normal lung development, Trop2 expression was higher at 90 days gestational age (GA; 4.0 +/- 0.8) than at 128 days GA (1.0 +/- 0.1), decreased to 0.5 +/- 0.1 at 142 days GA (full term approximately 147 days GA), and was positively correlated to lung cell proliferation rates (r = 0.953, P < 0.005). Trop2 expression was regulated by fetal lung expansion, but not by glucocorticoids. It was increased nearly threefold by 36 h of increased fetal lung expansion (P < 0.05) and was reduced to approximately 55% of control levels by reduced fetal lung expansion (P < 0.05). Trop2 expression was associated with lung cell proliferation during normal and altered lung growth, and the TROP2 protein colocalized with Ki-67-positive cells in the fetal lung. TROP2 was predominantly localized to fibroblasts and type II alveolar epithelial cells. Trop2 small interfering RNA decreased Trop2 expression by approximately 75% in cultured fetal rat lung fibroblasts and decreased their proliferation by approximately 50%. Cell viability was not affected. This study demonstrates that TROP2 regulates lung cell proliferation during development.