95) when compared to incubation without plasma (Figure 3), suggesting that the presence

of non-specific IgG does not alter the ability of hRS7 to mediate ADCC in Trop-2 expressing carcinosarcoma cells. Figure 3 Representative cytotoxicity experiments against the OMMT-ARK-2 cell line. Cytotoxicity in the presence of human plasma diluted 1:2 (with or without heat-inactivation) with effector cells and either hRS7 or rituximab control antibody in 5 h 51Cr-release assays. Addition of untreated plasma (diluted 1:2) to PBL in the presence of hRS7 significantly increased the ADCC achieved in the presence of hRS7 and PBL against OMMT-ARK-2 (P = 0.002). Addition of physiological concentrations of IgG (i.e. heat-inactivated plasma diluted 1:2) to PBL in the presence of hRS7 did not significantly alter the degree of ADCC achieved against OMMT-ARK-2 in the presence of hRS7 and PBL DAPT molecular weight (P = 0.95). Discussion In this study, we have investigated Trop-2 expression Selleckchem p38 MAPK inhibitor and localization by immunohistochemistry in uterine and ovarian carcinosarcomas and compared these findings to normal endometrium and ovarian control tissues. We have evaluated Trop-2 expression in multiple biologically aggressive, chemotherapy-resistant carcinosarcoma cell lines. Additionally, we have tested the sensitivity of these primary cell lines to immune-mediated cell death in the presence of hRS7, a humanized Trop-2 mAb made by grafting

the complementary-determining regions of its murine counterpart (mRS7) onto human IgG1 framework regions [11, 13–15]. To our knowledge, this is the first time that Trop-2 protein has been demonstrated to be significantly upregulated in human carcinosarcomas

from the uterus (UMMT) and ovary (OMMT), with negligible expression being detected in normal ovarian and uterine tissues. Significantly, Trop-2 positivity was confined to the epithelial component of the carcinosarcomas, without exception. Flavopiridol (Alvocidib) Although the relationship between high Trop-2 expression and the aggressiveness of human epithelial neoplasms remains unclear, there is evidence that Trop-2 functions in the transduction of cell signals regulating tumor cell growth and resistance to apoptosis. Trop-2 possesses cytoplasmic serine and tyrosine phosphorylation sites and might function as a cell signal transducer and regulator of tumor cell growth while increasing tumor cell resistance to apoptosis [16]. Consistent with this, Trop-2 has been identified as an oncogene, implicated in colon cancer tumor growth, migration, and invasion, which suggests that Trop-2- specific targeting may inhibit tumor cell growth, migration and invasion [17]. Several human cancers have been shown to express a bicistronic CYCLIN D1-TROP2 mRNA chimera that acts as an oncogene and is able to induce aggressive tumor growth [18]. These observations support the possibility that aberrant Trop-2 expression contributes to the enhanced biologic aggressiveness of multiple human cancers, including carcinosarcomas.