Takahiro Osawa

Heterogeneity of Tumor Endothelial Cells: Comparison between Tumor Endothelial Cells Isolated from High- and Low-Metastatic Tumors

An important concept in tumor angiogenesis is that tumor endothelial cells (TECs) are genetically normal and homogeneous. However, we previously reported that TECs differ from normal ECs. Whether the characteristics of TECs derived from different tumors differ remains unknown. To elucidate this, in this study, we isolated two types of TECs from high-metastatic (HM) and low-metastatic (LM) tumors and compared their characteristics. HM tumor-derived TECs (HM-TECs) showed higher proliferative activity and invasive activity than LM tumor-derived TECs (LM-TECs). Moreover, the mRNA expression levels of pro-angiogenic genes, such as vascular endothelial growth factor (VEGF) receptors 1 and 2, VEGF, and hypoxia-inducible factor-1α, were higher in HM-TECs than in LM-TECs. The tumor blood vessels themselves and the surrounding area in HM tumors were exposed to hypoxia. Furthermore, HM-TECs showed higher mRNA expression levels of the stemness-related gene stem cell antigen and the mesenchymal marker CD90 compared with LM-TECs. HM-TECs were spheroid, with a smoother surface and higher circularity in the stem cell spheroid assay. HM-TECs differentiated into osteogenic cells, expressing activated alkaline phosphatase in an osteogenic medium at a higher rate than either LM-TECs or normal ECs. Furthermore, HM-TECs contained more aneuploid cells than LM-TECs. These results indicate that TECs from HM tumors have a more pro-angiogenic phenotype than those from LM tumors.

Tumor-Derived Microvesicles Induce Proangiogenic Phenotype in Endothelial Cells via Endocytosis

Background Increasing evidence indicates that tumor endothelial cells (TEC) differ from normal endothelial cells (NEC). Our previous reports also showed that TEC were different from NEC. For example, TEC have chromosomal abnormality and proangiogenic properties such as high motility and proliferative activity. However, the mechanism by which TEC acquire a specific character remains unclear. To investigate this mechanism, we focused on tumor-derived microvesicles (TMV). Recent studies have shown that TMV contain numerous types of bioactive molecules and affect normal stromal cells in the tumor microenvironment. However, most of the functional mechanisms of TMV remain unclear. Methodology/Principal Findings Here we showed that TMV isolated from tumor cells were taken up by NEC through endocytosis. In addition, we found that TMV promoted random motility and tube formation through the activation of the phosphoinositide 3-kinase/Akt pathway in NEC. Moreover, the effects induced by TMV were inhibited by the endocytosis inhibitor dynasore. Our results indicate that TMV could confer proangiogenic properties to NEC partly via endocytosis. Conclusion We for the first time showed that endocytosis of TMV contributes to tumor angiogenesis. These findings offer new insights into cancer therapies and the crosstalk between tumor and endothelial cells mediated by TMV in the tumor microenvironment.

Impact of Diagnostic Ureteroscopy on Intravesical Recurrence and Survival in Patients With Urothelial Carcinoma of the Upper Urinary Tract

PURPOSE We determined whether diagnostic ureteroscopy for upper urinary tract cancer affects intravesical recurrence and cancer specific mortality. MATERIALS AND METHODS In a retrospective, multi-institutional study we evaluated 208 patients undergoing nephroureterectomy for upper urinary tract cancer who had no perioperative systemic chemotherapy, history of invasive bladder cancer, distant metastasis or incomplete followup data. Of these 208 patients 55 who composed the study group underwent diagnostic ureteroscopy before nephroureterectomy while 153 serving as controls did not. We analyzed intravesical recurrence and cancer specific survival using the Kaplan-Meier method with the log rank test used to assess significance. RESULTS There was no significant difference between the 2 groups in patient characteristics or upper urinary tract cancer stage and grade while followup, and the proportion of multiple tumors and lymphovascular invasion positive tumors were significantly greater in controls. The 2-year bladder recurrence-free survival rate was 60.0% in the study group and 58.7% in controls. There was no significant difference in the intravesical recurrence rate between the 2 groups (log rank test p = 0.972). Estimated Kaplan-Meier cancer specific survival was 88.3% and 78.1% at 5 years in the study and control groups, respectively (log rank test p = 0.0687). CONCLUSIONS Diagnostic ureteroscopy did not affect intravesical recurrence or cancer specific survival in patients with upper urinary tract cancer undergoing nephroureterectomy.

Role of lymph node dissection in the treatment of urothelial carcinoma of the upper urinary tract: Multi-institutional relapse analysis and immunohistochemical re-evaluation of negative lymph nodes

AIM To determine the role of lymph node dissection (LND) in the treatment of urothelial carcinoma (UC) of the upper urinary tract (UUT). PATIENTS AND METHODS [Study-1] A retrospective multi-institutional study evaluated 293 patients undergoing predominantly nephroureterectomy for UC of the UUT. Of 293 patients, 267 patients had pure UC and 26 demonstrated other histological components. Regarding the pathological node status, 130 patients had pN0 disease, 141 patients had pNx disease and 22 patients had pN+ disease. The sites of initial recurrence and time to first recurrence were reviewed. The sites of recurrence were classified as locoregional or distant recurrence. The relationship between node status and future recurrence was analyzed. [Study-2] Fifty-one patients treated by nephroureterectomy at Hokkaido University Hospital were included. All had LND and all LNs were negative on hematoxylin and eosin staining. We re-evaluated the presence of micrometastasis in LND specimens by anti-cytokeratin immunohistochemistory. RESULTS [Study-1] Of 293 patients, 76 developed disease relapse. Regional lymph node recurrence was the most common site (34 patients). On multivariate analyses that adjusted for the effect of tumor stage and tumor grade, pNx (skipping LND) was an adverse factor not only for locoregional recurrence, but also for distant relapse. [Study-2] Immunohistochemistry identified micrometastases in 7 (14%) of 51 patients. Regarding survival, 5 of these 7 patients with micrometastases were alive at last follow-up. CONCLUSIONS On relapse analysis, skipping LND was an adverse factor not only for locoregional recurrence, but also for distant relapse. Immunohistochemistry detected micrometastases in about 14% of patients previously diagnosed as pN0. These findings further support a potential therapeutic benefit of LND by eliminating micrometastases.

CXCR7: A novel tumor endothelial marker in renal cell carcinoma

Tumor angiogenesis is necessary for progression and metastasis of solid tumor. Tumor blood vessels are morphologically different from their normal counterparts. In this study, we isolated tumor endothelial cells (TECs) and revealed their abnormalities. We have compared the gene expression profiles of TECs and normal endothelial cells (NECs) by microarray analysis and found that several genes were upregulated in TECs. Expression of the chemokine receptor CXCR7 mRNA was higher in TECs than in NECs. However, information regarding the expression of CXCR7 in the tumor vessels of renal cell carcinoma is limited. CXCR7 and its ligand CXCL12 have been implicated in tumor cell survival. In this study, the expression of CXCR7 in the tumor vessels of renal cell carcinoma (RCC) was investigated. Real‐time PCR revealed higher expression level of CXCR7 in cultured TECs than in cultured NECs. Furthermore, similar to mouse TECs, immunostaining revealed strong expression of CXCR7 in vivo in human tumor vessels. These findings suggest that CXCR7 is a novel TEC marker and a target for antiangiogenic therapy for RCC.

THE ROLE OF LYMPH-NODE DISSECTION IN THE TREATMENT OF UPPER URINARY TRACT CANCER: A MULTI-INSTITUTIONAL STUDY

To determine the role of lymph‐node (LN) dissection in patients undergoing surgery for upper urinary tract (UUT) cancer.

Role of lymph node density in predicting survival of patients with lymph node metastases after radical cystectomy: a multi-institutional study.

Objectives:  To evaluate the prognostic role of different clinico‐pathological parameters in node‐positive patients treated by radical cystectomy.

Prostacyclin receptor in tumor endothelial cells promotes angiogenesis in an autocrine manner

Molecules highly expressed in tumor endothelial cells (TEC) are important for specific targeting of these cells. Previously, using DNA microarray analysis, we found that the prostacyclin receptor (IP receptor) gene was upregulated in TEC compared with normal endothelial cells (NEC). Although prostacyclin is implicated in re‐endothelialization and angiogenesis, its role remains largely unknown in TEC. Moreover, the effect of the IP receptor on TEC has not been reported. In the present study we investigated the function of the IP receptor in TEC. The TEC were isolated from two types of human tumor xenografts in nude mice, while NEC were isolated from normal counterparts. Prostacyclin secretion levels in TEC were significantly higher than those in NEC, as shown using ELISA. Real‐time RT‐PCR showed that the IP receptor was upregulated in TEC compared with NEC. Furthermore, migration and tube formation of TEC were suppressed by the IP receptor antagonist RO1138452. Immunohistostaining showed that the IP receptor was specifically expressed in blood vessels of renal cell carcinoma specimens, but not in glomerular vessels of normal renal tissue. These findings suggest that the IP receptor is a TEC‐specific marker and might be a useful therapeutic target. (Cancer Sci 2012; 103: 1038–1044)

Surgery for giant high-flow renal arteriovenous fistula: experience in one institution

To present five cases of renal arteriovenous fistula (RAVF) seen at our institution, with an emphasis on surgical treatment.

Pathological characteristics and clinical course of bladder tumour developing after nephroureterectomy

Study Type – Therapy (case series)
Level of Evidence 4