High TROP2 Expression Research Articles

High-grade, chemotherapy-resistant primary ovarian carcinoma cell lines overexpress human trophoblast cell-surface marker (Trop-2) and are highly sensitive to immunotherapy with hRS7, a humanized monoclonal anti-Trop-2 antibody

Objective. We evaluated the expression of human trophoblast cell-surface marker (Trop-2) and the potential of hRS7, a humanized monoclonal anti-Trop-2 antibody, as a therapeutic agent against chemotherapy-resistant ovarian disease. Methods. Trop-2 expression was evaluated by immunohistochemistry (IHC) in 50 ovarian serous papillary carcinoma specimens. Trop-2 expression was also evaluated by real-time PCR (qRT-PCR) and flow cytometry in a total of 6 primary ovarian cancer cell lines derived from patients with chemotherapy-resistant disease. Sensitivity to hRS7 antibody-dependent cellular cytotoxicity (ADCC) was tested in standard 5-hour 51Cr-release assays. The effect of serum and interleukin-2 (IL-2) on hRS7-mediated ADCC was also studied. Results. Trop-2 expression was found in 41 of 50 (82%) tumor tissues tested by IHC. 83% (5 of 6) of the ovarian cancer cell lines tested by qRT-PCR and flow cytometry demonstrated high Trop-2 expression. All primary ovarian cancer cell lines expressing Trop-2 were highly sensitive to hRS7-mediated ADCC in vitro (range of killing: 19.3% to 40.8%) ( p < 0.001). Negligible cytotoxicity against chemotherapy-resistant ovarian cancers was seen in the absence of hRS7 or in the presence of rituximab control antibody (range of killing: 1.1% to 8.9%). Human serum did not significantly inhibit hRS7-mediated cytotoxicity while incubation with IL-2 in addition to hRS7 further increased the cytotoxic activity ( p = 0.04). Conclusions. Trop-2 is highly expressed in chemotherapy-resistant ovarian cancer cell lines at mRNA and protein levels. Primary ovarian carcinoma cell lines are highly sensitive to hRS7-mediated cytotoxicity in vitro. hRS7 may represent a novel therapeutic agent for the treatment of high-grade, chemotherapy-resistant ovarian cancer.

Expression and clinical significance of Trop-2 in human pancreatic cancer

To investigate the expression and its clinical significance of Trop-2 in human pancreatic cancer. Reverse transcription-polymerase chain reaction (RT-PCR) and immunofluorescence assay were used to characterize the expression of Trop-2 in human pancreatic cancer. The expression of Trop-2 protein in 31 tumor tissue samples, including peritumoral tissue from patients with pancreatic cancer, was detected with immunohistochemistry by tissue microarray. The clinicopathological characteristics and the tissue expression of Trop-2 protein were analyzed statistically. RT-PCR, immunofluorescence assay and immunohistochemistry by tissue microarray showed a high expression of Trop-2 in pancreatic cancer. The expression rate of Trop-2 was much higher in pancreatic cancer than that in peritumoral tissues (87.1% vs 9.7%). And a high expression of Trop-2 in pancreatic cancer was correlated with the low-differentiated changes. It had statistical significance (P < 0.05). In contrast, no statistically significant correlation was found between the expression of Trop-2 and gender or age. The expression of Trop-2 is correlated with the development and malignancy of pancreatic cancer. As a clinical prognostic marker, Trop-2 may be a potential therapeutic target for pancreatic cancer.

Abstract 699: Uterine serous papillary carcinomas overexpress human trophoblast-cell-surface marker (Trop-2) and are highly sensitive to immunotherapy with hRS7, a humanized monoclonal anti-Trop-2 antibody

Abstract Purpose: To evaluate the expression of human trophoblast cell-surface marker (Trop-2) and the potential of hRS7, a humanized monoclonal anti-Trop-2 antibody, as a novel therapeutic strategy against Uterine Serous Papillary Carcinoma (USPC), a biologically aggressive and chemotherapy resistant variant of endometrial cancer. Methods: Trop-2 expression was evaluated by real time-PCR and flow cytometry in six primary uterine serous papillary carcinoma cell lines recently characterized in our laboratory. Sensitivity to hRS7 antibody-dependent-cellular-cytotoxicity (ADCC) was tested in standard 5-hrs 51Cr release-assays against primary USPC cell lines expressing different levels of Trop-2. Finally, to investigate the effect of interleukin-2 (IL-2) on hRS7-mediated ADCC, 5-hrs 51Cr assays were also conducted in the presence of low doses of IL-2 (i.e., 50-100 IU/ml). Results: Trop-2 mRNA transcript was significantly overexpressed in 3 out of 6 USPC primary cell lines when compared to normal human endometrial-cells (NEC) [p=0.005]. Consistent with RT-PCR data, high surface expression of Trop-2 was detected by flow cytometry in Trop-2 overexpressing cell lines [i.e., percentage of positive cells = 100% in all 3 positive cell lines, median (minimum-maximum) MFI (mean fluorescence intensity) of 184.2 (62.5-276.2)]. Importantly, while these USPC cell lines were found highly resistant to natural killer dependent cytotoxicity in the absence of the hRS7 antibody (range of killing 1.1% to 12.4%), they showed high sensitivity to hRS7-mediated ADCC in vitro (range of killing 28.2% to 64.4%) (P&amp;lt; 0.001). Incubation with IL-2 in addition to hRS7 further increased the cytotoxic activity against USPC cell lines overexpressing Trop-2 (p= 0.01). Conclusion: Primary USPC cell lines may overexpress Trop-2 at mRNA and protein level and are highly sensitive to hRS7-mediated cytotoxicity in vitro. hRS7 may represent a novel, potentially highly effective therapeutic strategy in patients harbouring advanced, recurrent or metastatic USPC refractory to standard treatment modalities. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 699.

Elevated expressions of MMP7, TROP2, and survivin are associated with survival, disease recurrence, and liver metastasis of colon cancer

Colorectal cancer is one of the most common cancers worldwide. We tested the hypothesis that differences in the expression of certain molecular markers of colon cancer may account for different clinical outcomes. Tissue microarray technology was used to assay the expression of 17 biological markers [beta-catenin, CD44v7, c-myc, cyclin D1, estrogen receptor beta, mitogen-activated protein kinase/extracellular signal-regulated kinase, maspin, matrix metalloproteinase-7 (MMP7), p53, Pin1, peroxisome proliferators-activated receptor-gamma, survivin, T cell transcription factor 4 (TCF4), transforming growth factor beta receptor II (TGFbetaR II), TGFbeta, TROP2, and Wnt] by immunohistochemistry in 620 colon cancer patients. The Cox proportional hazards regression model was applied to analyze the lifetime data, including time to death, time to recurrence, and time to liver metastasis. All the markers were present at significantly higher expression levels in tumor specimens than in normal colonic specimens. Kaplan-Meier analysis showed that high expression of TROP2, MMP7, and survivin were related to decreased survival; TCF4 and TROP2 were related to disease recurrence; and CD44v7, cyclin D1, MMP7, p53, survivin, and TCF4 were related to liver metastasis. However, the results of the multivariate analysis only showed that expression of MMP7, survivin, and TROP2 were significant predictors of lower patient survival, while TROP2 and MMP7 were significantly related to disease recurrence and liver metastasis, respectively. We conclude that elevated survivin, MMP7, and TROP2 expression levels are related to decreased survival. In addition, elevated MMP7 and TROP2 expression levels are predictors of disease recurrence and liver metastasis, respectively.

Trop2 identifies a subpopulation of murine and human prostate basal cells with stem cell characteristics

The epithelium of the adult prostate contains 3 distinct cell types: basal, luminal, and neuroendocrine. Tissue-regenerative activity has been identified predominantly from the basal cells, isolated by expression of CD49f and stem cell antigen-1 (Sca-1). An important question for the field is whether all basal cells have stem cell characteristics. Prostate-specific microarray databases were interrogated to find candidate surface antigens that could subfractionate the basal cell population. Tumor-associated calcium signal transducer 2 (TACSTD2/Trop2/M1S1/GA733-1) was identified because it was enriched after castration, in prostate sphere cells and in the basal fraction. In the murine prostate, Trop2 shows progenitor characteristics such as localization to the region of the gland proximal to the urethra and enrichment for sphere-forming and colony-forming cells. Trop2 subfractionates the basal cells into 2 populations, both of which express characteristic basal cell markers by quantitative PCR. However, only the basal cells expressing high levels of Trop2 were able to efficiently form spheres in vitro. In the human prostate, where Sca-1 is not expressed, sphere-forming progenitor cells were also isolated based on high expression of Trop2 and CD49f. Trop2-expressing murine basal cells could regenerate prostatic tubules in vivo, whereas the remaining basal cells had minimal activity. Evidence was found for basal, luminal, and neuroendocrine cells in prostatic tubules regenerated from Trop2(hi) basal cells. In summary, functionally distinct populations of cells exist within the prostate basal compartment and an epithelial progenitor can give rise to neuroendocrine cells in vivo.

High expression of TROP2 correlates with poor prognosis in pancreatic cancer

Pancreatic cancer is one of the most devastating human malignancies. Despite considerable research efforts, it remains resistant to almost all available treatment regimens. The human trophoblast cell-surface antigen, TROP2, was found to be strongly expressed in a variety of human epithelial cancers, correlating with aggressiveness and poor prognosis. TROP2 antigen expression was investigated retrospectively by immunohistochemistry in paraffin-embedded primary tumour tissue samples from a series (n=197) of consecutive patients with pancreatic adenocarcinoma. Survival was calculated using Kaplan–Meier curves. Parameters found to be of prognostic significance in univariate analysis were verified in a multivariate Cox regression model. TROP2 overexpression was observed in 109 (55%) of 197 pancreatic cancer patients and was significantly associated with decreased overall survival (P<0.01). By univariate analysis, TROP2 overexpression was found to correlate with the presence of lymph node metastasis (P=0.04) and tumour grade (P=0.01). Furthermore, in the subgroup of patients treated surgically with curative intent, TROP2 overexpression significantly correlated with poor progression-free survival (P<0.01). Multivariate analyses revealed TROP2 to be an independent prognosticator. These findings suggest for the first time that TROP2 could be a novel prognostic biomarker for pancreatic cancer. Targeting TROP2 might be a useful treatment approach for patients with pancreatic cancer overexpressing this cell-surface marker.

Clinical Significance ofTROP2Expression in Colorectal Cancer

To identify cancer-related genes, the expression profiles of colorectal cancer cells and normal epithelial cells were examined and compared using laser microdissection and cDNA microarray analysis. From these combined techniques, several cancer-related genes, including TROP2, were identified. TROP2 is known as a calcium signal transducer and is highly expressed in several types of tumors. However, no studies have investigated the significance of TROP2 expression in colorectal cancer. Thus, the expression status of TROP2 was investigated in 74 colorectal cancer samples by quantitative real-time reverse transcription-PCR and immunohistochemical studies. Laser microdissection and cDNA microarray analysis showed that there were 84 overexpressed genes in cancer cells. One of the highly overexpressed genes was TROP2. Quantitative real-time reverse transcription-PCR showed that TROP2 expression in cancer samples was significantly higher than in normal samples (P < 0.001). The samples were divided into high (n = 26) and low (n = 48) TROP2 expression groups. The cases with high TROP2 expression showed a higher frequency of liver metastasis (P = 0.005) and more cancer-related death (P = 0.046). Those cases also had an inclination of deeper depth of invasion (P = 0.064) and more lymph node metastasis (P = 0.125). Interestingly, the patients with high TROP2 expression tumors had poorer prognosis (P = 0.0036). Multivariate analysis showed that TROP2 expression status was an independent prognostic factor (relative risk, 2.38; 95% confidence interval, 1.29-4.74; P < 0.01). TROP2 is one of the cancer-related genes that correlates with biological aggressiveness and poor prognosis of colorectal cancer. Thus, TROP2 is a possible candidate gene for diagnosis and molecular target therapy of colorectal cancer.