Beschreibung: Purpose: The objective of the study was to determine whether astrocytes and brain endothelial cells protect glioma cells from temozolomide through an endothelin-dependent signaling mechanism and to examine the therapeutic efficacy of the dual endothelin receptor antagonist, macitentan, in orthotopic models of human glioblastoma. Experimental Design: We evaluated several endothelin receptor antagonists for their ability to inhibit astrocyte- and brain endothelial cell–induced protection of glioma cells from temozolomide in chemoprotection assays. We compared survival in nude mice bearing orthotopically implanted LN-229 glioblastomas or temozolomide-resistant (LN-229 Res and D54 Res ) glioblastomas that were treated with macitentan, temozolomide, or both. Tumor burden was monitored weekly with bioluminescence imaging. The effect of therapy on cell division, apoptosis, tumor-associated vasculature, and pathways associated with cell survival was assessed by immunofluorescent microscopy. Results: Only dual endothelin receptor antagonism abolished astrocyte- and brain endothelial cell–mediated protection of glioma cells from temozolomide. In five independent survival studies, including temozolomide-resistant glioblastomas, 46 of 48 (96%) mice treated with macitentan plus temozolomide had no evidence of disease ( P 〈 0.0001), whereas all mice in other groups died. In another analysis, macitentan plus temozolomide therapy was stopped in 16 mice after other groups had died. Only 3 of 16 mice eventually developed recurrent disease, 2 of which responded to additional cycles of macitentan plus temozolomide. Macitentan downregulated proteins associated with cell division and survival in glioma cells and associated endothelial cells, which enhanced their sensitivity to temozolomide. Conclusions: Macitentan plus temozolomide are well tolerated, produce durable responses, and warrant clinical evaluation in glioblastoma patients. Clin Cancer Res; 21(20); 4630–41. ©2015 AACR .

Beschreibung: Purpose: Circulating endothelial cells (CEC) have been widely used as a prognostic biomarker and regarded as a promising strategy for monitoring the response to treatment in several cancers. However, the presence and biologic roles of CECs have remained controversial for decades because technical standards for the identification and quantification of CECs have not been established. Here, we hypothesized that CECs detected by flow cytometry might be monocytes rather than endothelial cells. Experimental Design: The frequency of representative CEC subsets (i.e., CD45 – /CD31 + , CD45 – /CD31 + /CD146 + , CD45 – /CD31 + /CD105 + ) was analyzed in the peripheral blood of patients with gynecologic cancer ( n = 56) and healthy volunteers ( n = 44). CD45 – /CD31 + cells, which are components of CECs, were isolated and the expression of various markers (CD146, CD105, vWF, and CD144 for endothelial cells; CD68 and CD14 for monocytes) was examined by immunocytochemistry. Results: CD45 – /CD31 + /CD105 + cells were significantly increased in the peripheral blood of patients with cancer, whereas evaluation of CD45 – /CD31 + /CD146 + cells was not possible both in patients with cancer and healthy controls due to the limited resolution of the flow cytometry. Immunocytochemistry analyses showed that these CD45 – /CD31 + /CD105 + cells did not express vWF and CD146 but rather CD144. Furthermore, CD45 – /CD31 + /CD105 + cells uniformly expressed the monocyte-specific markers CD14 and CD68. These results suggest that CD45 – /CD31 + /CD105 + cells carry the characteristics of monocytes rather than endothelial cells. Conclusions: Our data indicate that CD45 – /CD31 + /CD105 + circulating cells, which are significantly increased in the peripheral blood of patients with gynecologic cancer, are monocytes rather than endothelial cells. Further investigation is required to determine the biologic significance of their presence and function in relation with angiogenesis. Clin Cancer Res; 19(19); 5340–50. ©2013 AACR .

Beschreibung: Purpose: Anaplastic thyroid carcinoma (ATC) is one of the most invasive human cancers and has a poor prognosis. Molecular targets of ATC that determine its highly aggressive nature remain unidentified. This study investigated L1 cell adhesion molecule (L1CAM) expression and its role in tumorigenesis of ATCs. Experimental Design: Expression of L1CAM in thyroid cancer was evaluated by immunohistochemical analyses of tumor samples from patients with thyroid cancer. We investigated the role of L1CAM in proliferation, migration, invasion, and chemoresistance using short hairpin RNA (shRNA) knockdown experiments in human ATC cell lines. Finally, we evaluated the role of L1CAM on tumorigenesis with ATC xenograft assay in a nude mouse model. Results: L1CAM expression was not detectable in normal follicular epithelial cells of the thyroid or in differentiated thyroid carcinoma. In contrast, analysis of ATC samples showed specifically higher expression of L1CAM in the invasive area of the tumor. Specific knockdown of L1CAM in the ATC cell lines, FRO and 8505C, caused a significant decrease in the proliferative, migratory, and invasive capabilities of the cells. Suppression of L1CAM expression in ATC cell lines increased chemosensitivity to gemcitabine or paclitaxel. Finally, in an ATC xenograft model, depletion of L1CAM markedly reduced tumor growth and increased the survival of tumor-bearing mice. Conclusions: We report that L1CAM is highly expressed in the samples taken from patients with ATCs. L1CAM plays an important role in determining tumor behavior and chemosensitivity in cell lines derived from ATCs. Therefore, we suggest that L1CAM may be an important therapeutic target in patients with ATCs. Clin Cancer Res; 18(11); 3071–8. ©2012 AACR .

Beschreibung: Purpose: Durable complete remission of metastatic renal cell carcinoma (RCC) has rarely been achieved with current treatment modalities. To solve this problem, alternative therapeutic options with high efficacy and minimal side effects are strongly needed. Experimental Design: Mesenchymal stem cells (MSC) were engineered to coexpress dodecameric TRAIL and herpes simplex virus thymidine kinase (MSC/dTRAIL-TK). The antitumor effects of MSCs expressing dTRAIL (MSC/dTRAIL) or HSV-TK alone (MSC/TK) and MSC/dTRAIL-TK were compared with murine RCC cells using in vitro coculture system and in vivo experimental lung metastasis model. The effects of different doses and schedules of engineered MSCs on mice survival were also evaluated. Results: MSC/dTRAIL-TK exerted stronger apoptotic response in Renca cells than did MSC/TK or MSC/dTRAIL after ganciclovir (GCV) treatment. In vivo imaging results suggest that MSCs reside longer in the lungs of metastatic tumor-bearing mice, compared with that of control mice, regardless of genetic engineering. In addition, MSC/dTRAIL-TK treatment followed by ganciclovir administrations significantly decreased the number of tumor nodules in the lung, to a greater degree than MSC/dTRAIL or MSC/TK, and led to a prolonged survival. More importantly, the antimetastatic effect of MSC/dTRAIL-TK was markedly enhanced by repeated injections but not by increased dose, and resulted in 100% survival of tumor-bearing mice after three injections. Conclusion: Sequential combination gene therapy using MSC/dTRAIL-TK achieved long-term remission of metastatic RCC without noticeable toxicity. Our findings provide an innovative therapeutic approach to completely eradicate metastatic tumors by simple, repeated administrations of MSC/dTRAIL-TK. Clin Cancer Res; 19(2); 415–27. ©2012 AACR .

Beschreibung: Purpose: Alternative lengthening of telomeres (ALT), a telomerase-independent telomere maintenance mechanism, is strongly associated with ATRX and DAXX alterations and occurs frequently in pancreatic neuroendocrine tumors (PanNET). Experimental Design: In a Korean cohort of 269 surgically resected primary PanNETs and 19 sporadic microadenomas, ALT status and nuclear ATRX and DAXX protein expression were assessed and compared with clinicopathologic factors. Results: In PanNETs, ALT or loss of ATRX/DAXX nuclear expression was observed in 20.8% and 19.3%, respectively, whereas microadenomas were not altered. ALT-positive PanNETs displayed a significantly higher grade, size, and pT classification (all, P 〈 0.001). ALT also strongly correlated with lymphovascular ( P 〈 0.001) and perineural invasion ( P = 0.001) and the presence of lymph node ( P 〈 0.001) and distant metastases ( P = 0.002). Furthermore, patients with ALT-positive primary PanNETs had a shorter recurrence-free survival [HR = 3.38; 95% confidence interval (CI), 1.83–6.27; P 〈 0.001]. Interestingly, when limiting to patients with distant metastases, those with ALT-positive primary tumors had significantly better overall survival (HR = 0.23; 95% CI, 0.08–0.68; P = 0.008). Similarly, tumors with loss of ATRX/DAXX expression were significantly associated with ALT ( P 〈 0.001), aggressive clinical behavior, and reduced recurrence-free survival ( P 〈 0.001). However, similar to ALT, when limiting to patients with distant metastases, loss of ATRX/DAXX expression was associated with better overall survival ( P = 0.003). Conclusions: Both primary ALT-positive and ATRX/DAXX-negative PanNETs are independently associated with aggressive clinicopathologic behavior and displayed reduced recurrence-free survival. In contrast, ALT activation and loss of ATRX/DAXX are both associated with better overall survival in patients with metastases. Therefore, these biomarkers may be used as prognostic markers depending on the context of the disease. Clin Cancer Res; 23(6); 1598–606. ©2016 AACR .