RANKL synthesized by both stromal cells and cancer cells plays a crucial role in osteoclastic bone resorption induced by oral cancer

The molecular mechanisms underlying bone destruction by invading oral cancer are not well understood. Using IHC, we demonstrated that receptor activator of nuclear factor-κB ligand (RANKL)-positive fibroblasts and cancer cells were located at sites of bone invasion in human oral cancers. HSC3 and HO-1-N-1, human oral cancer cell lines, expressed RANKL and stimulated Rankl expression in the UAMS-32 murine osteoblastic cell line. We discriminated the roles of RANKL synthesized by stromal cells and cancer cells in cancer-associated bone resorption by using species-specific RANKL antibodies against murine RANKL and human RANKL, respectively. Osteoclastogenesis induced by the conditioned medium of HSC3 and HO-1-N-1 cells in a co-culture of murine bone marrow cells and UAMS-32 cells was inhibited by the addition of antibodies against either mouse or human RANKL. HSC3-induced bone destruction was greatly inhibited by the administration of anti-mouse RANKL antibody in a xenograft model. HO-1-N-1-induced bone destruction was inhibited by the administration of either anti-mouse or anti-human RANKL antibody. Bone destruction induced by the transplantation of human RANKL-overexpressing cells (HSC3-R2) was greatly inhibited by the injection of anti-human RANKL antibody. The present study revealed that RANKL produced by both stromal and cancer cells is involved in oral cancer-induced osteoclastic bone resorption. These results provide important information for understanding the cellular and molecular basis of cancer-associated bone destruction and the mechanism of action underlying RANKL antibody (denosumab) therapy.

Pim-1 activation of cell motility induces the malignant phenotype of tongue carcinoma

Pim-1 is a serine/threonine kinase as well as a proto-oncogene that induces T-cell lymphoma. Pim-1 induces cell cycle progression in cooperation with c-Myc and acts as an inhibitor of apoptotic cell death, actions that are involved in blood cell oncogenesis. However, little is known regarding the role of Pim-1 in oral carcinogenesis. We investigated Pim-1 expression in tongue squamous cell carcinoma (SCC) and examined its clinicopathological features. Western blotting was performed in 6 oral SCC cell lines, with Pim-1 being detected in all 6 of the lines. Immunohistochemical detection of Pim-1 was carried out in 39 cases of tongue SCC and analyzed in terms of its associated clinicopathological features. Pim-1 was expressed in 17/39 cases of tongue carcinoma, and was significantly correlated with lymph node metastasis. The role of Pim-1 in cell motility was further examined in HSC3 cells using the GTP-binding assay for Rho family protein, the motility assay and siRNA treatment. Rac1 activation was observed, and cell motility was reduced when Pim-1 was knocked down by siRNA. These results indicate that Pim-1 is involved in the carcinogenesis of oral SCC and is correlated to metastasis, which is in part associated with the enhancement of cell motility.

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.

Abstract 4357: The role of lysyl oxidase on proangiogenic phenotypes of tumor endothelial cells

Introduction and Objectives: The molecules which are highly expressed in tumor endothelial cell (TEC) are important to target TEC more specifically. We found LOX gene was upregulated in TEC compared to normal endothelial cell (NEC) by DNA microarray analysis in three different types of human tumor xenografts in nude mouse including renal cell carcinoma (RCC). LOX is an enzyme which is reported to play a critical role in the metastatic potential of tumor, possibly promoting tumor cell trafficking into the premetastatic niche in various types of malignancies. However, the effect of LOX on TEC has not been reported. To investigate whether LOX might be a TEC-specific target in cancer therapy, we analyzed its expression in clinical sample and examined the function of LOX on TEC. Methods: We successfully purified human TEC (hTEC) and NEC (hNEC) from surgically resected RCC and normal parenchyma from six patients, respectively. Using cultured hTEC and hNEC, competitive reverse transcription-polymerase chain reaction (RT-PCR) was performed. LOX expression level was investigated using immunohistochemistry (IHC). To explore the role of LOX in TEC, mouse TEC (mTEC) and NEC (mNEC) were isolated from human tumor xenografts in nude mouse and the normal counterparts, respectively. To investigate the function of LOX, LOX was knock-downed using siRNA and TEC phenotypic changes were analyzed by migration assay and vascular tube formation assay. In addition, we investigated the effect of α-aminopropionitrile (BAPN), an irreversible inhibitor of LOX, on tumor angiogenesis and metastatic colonization in vivo. Results: LOX expression levels were higher in isolated TEC than NEC both in human (Tissues: clear cell carcinoma 6; Stage T1, 3; T3, 3; Grade 1, 1; Grade 2, 2; Grade 3, 3) and mouse by RT-PCR. In IHC, LOX was detected in blood vessels in human RCC, not in normal tissue. Cell migration and tube formation of mTEC were suppressed by LOX knock-down using siRNA with decrease in phosphorylation of focal adhesion kinase (Tyr397). Furthermore, BAPN specifically inhibited tumor angiogenesis and micrometastasis in vivo, via inhibition of LOX activity of TEC. Conclusions: Our findings suggest that LOX upregulated in TEC contributes in their proangiogenic phenotype and plays key roles in tumor metastasis. LOX might be a TEC-specific target and be useful for cancer therapeutic purposes.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4357. doi:1538-7445.AM2012-4357

Abstract 5275: Biglycan is a specific marker and an autocrine angiogenic factor of tumor endothelial cells

Tumor angiogenesis is necessary for solid tumor progression and metastasis. Tumor blood vessels are morphologically different from their normal counterparts. We isolated tumor endothelial cells (TECs), demonstrated their abnormalities, compared gene expression profiles of TECs and normal endothelial cells (NECs) by microarray analysis and identified several genes upregulated in TECs. We focused on the gene encoding biglycan, a small leucine-rich repeat proteoglycan. Biglycan is overexpressed in inflammation and fibrosis. However, there has been no report about the expression or the function of biglycan in TEC. In this study, we investigated the expression and the role of biglycan in TECs. Real-time PCR, western blotting and immunocytochemistry revealed higher biglycan expression levels in TECs than in NECs. Furthermore, we confirmed that biglycan was secreted from TECs. Biglycan knockdown inhibited cell migration and tube formation in TECs. TLR2 and TLR4 are the biglycan receptors. TLR2 and TLR4 blocking antibodies suppressed biglycan mediated cell migration and tube formation. We isolated TECs from human renal cell carcinoma tissue and NECs from normal renal tissue in the same patients. TECs and NECs were obtained from six patients. Real-time RT-PCR revealed that the biglycan expression levels were significantly higher in four of the six TEC samples than in the corresponding NEC samples. Furthermore, immunostaining revealed strong biglycan expression in vivo in several human tumor vessels, as in mouse TECs. Biglycan was detected in the sera of cancer patients but was hardly detected in those of healthy volunteers. Biglycan is an autocrine angiogenic factor stimulating tumor endothelial cell migration and tube formation. These findings suggested that biglycan is a novel TEC marker and a target for anti-angiogenic therapy.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5275. doi:1538-7445.AM2012-5275

Abstract 1487: 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.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1487. doi:1538-7445.AM2012-1487

Abstract 1370: Tumor endothelial cells acquire drug resistance by MDR1 upregulation via VEGF signaling in tumor microenvironment

Tumor endothelial cells (TECs) are therapeutic targets in antiangiogenic therapy. Contrary to the traditional assumption, it has been reported that TECs can be genetically abnormal and might acquire drug resistance. In this study, mouse TECs and normal ECs (NECs) were isolated to investigate drug resistance of TECs and the mechanism by which it is acquired. TECs were more resistant to paclitaxel with upregulation of multidrug resistance 1 (MDR1) mRNA, which encodes the P-glycoprotein, compared to NECs. Normal human microvascular ECs (HMVECs) were cultured in tumor-conditioned medium (tumor CM) and were found to become more resistant to paclitaxel through MDR1 mRNA upregulation and nuclear translocation of Y-box-binding protein 1 (YB-1), which is an MDR1 transcription factor. Vascular endothelial growth factor (VEGF) receptor 2 (VEGFR2) and Akt were activated in HMVECs by tumor CM. We observed that tumor CM contained a significantly high level of VEGF. A VEGF receptor kinase inhibitor, Ki8751, and a PI3K/Akt inhibitor, LY294002, blocked tumor CM-induced MDR1 upregulation. MDR1 upregulation via the VEGF/VEGFR pathway in the tumor microenvironment is one of the mechanisms of drug resistance acquired by TECs. We observed that VEGF secreted from tumors upregulated MDR1 through VEGFR2 and Akt activation. This is a novel mechanism of acquisition of drug resistance by TECs in a tumor microenvironment.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1370. doi:1538-7445.AM2012-1370

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.

Altered angiogenesis in the tumor microenvironment

Tumor blood vessels play an important role in tumor progression and metastasis. Thus, targeting the tumor blood vessels is an important strategy in cancer therapy. Tumor blood vessels generally arise from pre-existing vessels and have been thought to be genetically normal. However, they have been shown to differ from their normal counterparts, e.g. with regard to the morphological changes. We isolated tumor endothelial cells (TEC) from mouse tumor xenografts and showed that they were abnormal. TEC up-regulate many genes, proliferate more rapidly and migrate more than normal endothelial cells (NEC). Furthermore, the TEC in our study were cytogenetically abnormal. We concluded that TEC can acquire cytogenetic abnormalities while in the tumor microenvironment. In order to develop ideal antiangiogenic therapies, understanding the crosstalk between blood vessels and the tumor microenvironment is important. This review considers the current studies on TEC abnormalities and discusses the possible mechanism by which the tumor microenvironment produces abnormal TEC.

RANKL expression specifically observed in vivo promotes epithelial mesenchymal transition and tumor progression

Recent findings have focused attention on the molecular consequences of the microenvironment in tumor progression, but events occurring in cancer cells themselves in response to their ambient conditions remain obscure. Here, we identify receptor activator of nuclear factor κB ligand (RANKL) as a microenvironment-specific factor essential for tumorigenesis in vivo, using head and neck squamous cell carcinoma (HNSCC) as a model. In human HNSCC tissues, RANKL is abundantly expressed, and its expression level correlates with the histological grade of differentiation. RANKL levels are significantly higher in poorly differentiated SCCs than in well or moderately differentiated SCCs. In contrast, all HNSCC cell lines tested displayed extremely low RANKL expression; however, RANKL is efficiently up-regulated when these cell lines are inoculated in the head and neck region of mice. RANKL expression is restored in a microenvironment-specific manner, and cannot be observed when the cells are inoculated in the hindlimbs. Forced expression of RANKL compensates for tumor growth in the hindlimb milieu, promotes epithelial mesenchymal transition, and induces tumor angiogenesis, in a manner independent of vascular endothelial growth factor (VEGF). These results implicate RANKL expression causatively in tumor growth and progression in HNSCC in vivo. RANKL may provide a novel functional marker for biological malignancy and a therapeutic target based on the specific nature of the microenvironment.

Abstract 906: Gene expression analysis of circulating endothelial cells in cancer patients

It has been reported that the number of circulating endothelial cells (CECs) is higher in cancer patients compared to healthy controls. CECs may be acting as possible markers of vascular turnover or damage. Elevated level of CEC number has been reported to be correlated with tumor progression or response to anti-angiogenic therapy. Tumor endothelial cells (TECs) could be shed into circulation and being included in CECs. We have reported that primary cultured mouse TECs express reported TEC-specific markers, such as CD13, TEMs, Dickkopf-3 (Dkk-3) and others.

In this study, we analyzed the expression of these TEC markers in CECs in lung cancer patients. Before and/or after dissecting tumor tissue, blood was collected and RNAs from peripheral blood mononuclear cells (PBMCs) were extracted from the patients. And mRNA expression of EC markers and several TEC markers, including both reported and novel candidate, were analyzed. We detected CD31 and CD105 expression in both lung cancer patients’ and healthy controls’ PBMCs. The expression levels of TEC markers and several novel TEC candidate genes were analyzed and compared with healthy controls.

Expression levels of several TEC markers including novel TEC marker X and Y, which were expressed in human cultured TECs, were higher in cancer patients than in healthy controls.

However, it was difficult for us to detect TEC marker gene expressions in PBMC from cancer patients’ blood since TECs are very small population in PBMC (0.2%). In order to obtain more concentrated TECs from lung cancer patients’ blood, we used blood from lung tumor specimen when lung cancer specimens were dissected under video-assisted thoracic surgery.

This specimen (lung tumor specimen blood) contains pulmonary vein blood and it was thought to contain more TECs shed from lung tumor. So we isolated mononuclear cells form this specimen and analyzed TEC marker gene expressions. We sorted mononuclear cells by flow cytometry using anti-CD31 and anti-CD45. TECs are supposed to be included in CD31(+) CD45(−) (Q4) fraction. Novel TEC candidate marker gene X and Y expressions were detected, in crude mononuclear cells from the lung tumor specimen blood at high levels, but very low levels in CD31(−))CD45(+) (Q1) fraction or CD31(+)CD45(+) (Q2) fraction, leading a possibility that the gene X and Y were highly expressed in Q4 fraction.

These results suggest that the lung tumor specimen blood can be one of useful materials to discover novel CTEC marker genes in lung cancer patients, and that these markers could be surrogate markers or predicted markers for anti-angiogenic therapy in lung cancer patients.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 906. doi:10.1158/1538-7445.AM2011-906

Abstract 1509: Analysis of interaction between tumor endothelial cells and tumor cells

Interaction between tumor endothelial cells (TECs) and tumor cells plays a key role in the early stage of hematogenous metastasis. TECs provide the principal route by which tumor cells exit the primary tumor site and enter the circulation. We have reported TECs are different from normal endothelial cells (NECs) in various aspects, such as chromosomal abnormality and gene expression profiles. In this study, we isolated two types of TECs from different human tumor xenografts in nude mice to analyze interaction between TECs and tumor cells. One is HMTEC isolated from highly metastatic tumor and the other is LMTEC from low metastatic tumor. We also isolated NEC from dermis of normal nude mouse as normal control. HMTEC expressed higher levels of mRNA of angiogenesis-related genes than LMTEC or NEC. We hypothesized HMTECs may promote metastasis, in particular, intravasation at the primary site. We investigated the roles of TECs in tumor metastasis; 1) migration of tumor cells towards TECs, 2) adhesion to endothelial layer, 3) crossing the endothelium. Tumor cells migrated towards conditioned-media (CM) from HMTEC more than LMTEC-CM or NEC-CM in vitro. Tumor cells were more adhesive to HMTEC than to LMTEC or NEC. They migrated through the HMTEC-monolayer most among all ECs in transendothelial migration assay. These results suggested that HMTEC may help tumor cells to metastasize. Finally, we analyzed the effects of CM from highly metastatic tumor cells on NECs. Tumor CM induced mRNA expressions of several genes, such as CXCL12, VEGFA and extracellular matrix in NEC. Tumor cells more migrated towards tumor CM- treated NEC than non-treated NEC. Tumor cells adhered more to the tumor CM- treated NEC than to non-treated NEC. These results suggest that TECs “educated” in tumor microenvironment which have highly metastatic potential, may be collaborating with tumor cells for metastasis.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1509. doi:10.1158/1538-7445.AM2011-1509

Phenotype of tumor lymphatic vessels is a prognostic factor in human tongue squamous cell carcinoma

Tumor metastasis to lymph nodes occurs through the lymphatic vessels located in the tumor circumference. However, few studies have focused on the phenotypes of lymphatic vessels around these tumors. We investigated the characteristics of the lymph vessels of tongue squamous cell carcinoma (SCC) and compared them to clinicopathological characteristics. A total of 43 patients diagnosed as having tongue SCC consulted Hokkaido University Hospital were examined. The lymphatic vessels were identified by antibody D2-40 and the number and diameter of tumor lymphatic vessels were measured. The proliferative activity of lymphatic endothelial cells was also examined by immunostaining using antibody MIB-1. We then measured the DNA density of lymphatic endothelial cells in normal and tumor tissues. The number of tumor lymphatic vessels significantly increased in highly metastatic cases of tongue SCC, particularly in cases with a large number of micro lymphatic vessels. A significant correlation was found between the metastatic and proliferative activity of tumor lymphatic endothelial cells. Moreover, the DNA density of tumor lymphatic endothelial cells increased compared to normal tissues. These results suggest that the phenotypes of tumor lymphatic endothelial cells are an indicator of lymph node metastasis of tongue SCC.

A multiple primary carcinoma consisting of leukoplakia and SCC: a case report with p53 mutation analysis

Patients with an oral squamous cell carcinoma (OSCC) often develop multiple malignant lesions. This report examined whether individual tumours developed in a patient show the same genetic alteration, such as p53 mutations. This case study describes three SCCs and three leukoplakias which developed simultaneously in a single 67-year-old Japanese man. A p53 mutation was detected in two of the three SCCs and one of the three leukoplakias. One SCC had a missense mutation at codon 285 (GAG>AAG, Glu>Lys) and the other a nonsense mutation at codon 336, and the leukoplakia had a missense mutation at codon 273 (CGT>CAT, Arg>His). This case showed that individual oral tumours may have different genetic changes even when they develop in a single patient. Therefore, this report provided strong evidence that in cases of multiple tumours it is necessary to design tailor-made therapies for each individual tumour rather than a single standardised therapy for all multiple tumours.

Adrenomedullin antagonist suppresses tumor formation in renal cell carcinoma through inhibitory effects on tumor endothelial cells and endothelial progenitor mobilization

Adrenomedullin (AM) is a multifunctional 52-amino acid peptide. AM has several effects and acts as a growth factor in several types of cancer cells. Our previous study revealed that an AM antagonist (AMA) suppressed the growth of pancreatic tumors in mice, although its mechanism was not elucidated. In this study, we constructed an AMA expression vector and used it to treat renal cell carcinoma (RCC) in mice. This AMA expression vector significantly reduced tumor growth in mice. In addition, microvessel density was decreased in AMA-treated tumors. To analyze the effect of AMA on tumor angiogenesis in this model, tumor endothelial cells (TECs) were isolated from RCC xenografts. TEC proliferation was stimulated by AM and it was inhibited by AMA significantly. AM induced migration of TECs and it was also blocked by AMA. However, normal ECs (NECs) were not affected by either AM or AMA. These results demonstrate that AMA has inhibitory effects on TECs specifically, not on NEC, thereby inhibiting tumor angiogenesis. Furthermore, we showed that vascular endothelial growth factor-induced mobilization of endothelial progenitor cell (EPC) into circulation was inhibited by AMA. These results suggest that AMA can be considered a good anti-angiogenic reagent that selectively targets TECs and EPC in renal cancer.

De novo mutation in the DSPP gene associated with dentinogenesis imperfecta type II in a Japanese family

Dentinogenesis imperfecta (DGI) type II is one of the most common dominantly inherited dentin defects, in which both the primary and permanent teeth are affected. Here, we report a Japanese family with autosomal-dominant DGI type II, including both molecular genetic defects and pathogenesis with histological analysis. Mutation analysis revealed a mutation (c.53T>A, p.V18D, g.1192T>A) involving the second nucleotide of the first codon within exon 3 of the dentin sialophosphoprotein (DSPP) gene. This mutation has previously been reported in a Korean family. Thus far, 24 allelic DSPP mutations have been reported, and this is the seventh mutation involving the DSPP V18 residue. Among those, only one other was shown to be caused by a de novo mutation, and that mutation also affected the V18 amino acid residue. The DSPP V18 residue is highly conserved among other mammalian species. These findings thus suggest that the V18 amino acid might be a sensitive mutational hot spot, playing a critical role in the pathogenesis of DGI.

Abstract 1308: Cytogenetic abnormalities of tumor endothelial cells in human malignant tumors

An important concept in tumor angiogenesis has been that tumor blood vessels contain genetically normal and stable endothelial cells (ECs), unlike tumor cells, which typically display genetic instability. Chromosomal aberration in human tumor endothelial cells (hTECs) in carcinoma has not yet been investigated. Here we isolated TECs from 20 human renal cell carcinomas (RCCs) and analyzed their cytogenetic abnormalities. The degree of aneuploidy was analyzed by fluorescence in situ hybridization using chromosome 7 and chromosome 8 DNA probes in isolated hTECs. In human RCCs, 22-58% (median 33%) of uncultured hTECs were aneuploid, whereas normal ECs were diploid. The mechanisms of TEC aneuploidy were studied using mouse TECs (mTECs) isolated from xenografts of human epithelial tumors. To investigate the contribution of progenitor cells to aneuploidy in mTECs, CD133 positive and CD133 negative mTECs were compared for aneuploidy. CD133 positive mTECs showed aneuploidy more frequently than CD133 negative mTECs. This is the first report showing cytogenetic abnormality of hTECs in carcinoma, contrary to traditional belief. It is suggested that cytogenetic alterations in tumor vessels of carcinoma can occur and may play a signicant role in modifying tumor-stromal interactions.

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 1308.

Abstract 3432: A green tea polyphenol epigallocatechin-3 gallate specifically targets tumor-associated endothelial cells

A green tea polyphenol, epigallocatechin-3 gallate (EGCG) suppresses tumor growth in vivo. We investigated mechanisms of specific tumor angiogenesis inhibition using tumor-associated endothelial cells (TECs), peripheral blood-derived ECs, and normal endothelial cells (NECs). TECs were isolated and cultured from human tumor xenografts in nude mice. Peripheral blood-derived ECs were isolated from peripheral blood of nude mice. EGCG suppressed migration of TECs and peripheral blood-derived ECs. EGCG also inhibited the phosphorylation of Akt in TECs and peripheral blood-derived ECs. The PI3K inhibitor, LY294002 blocked the migration of TECs induced by VEGF. Furthermore, VEGF-induced mobilization of CD133/VEGFR-2 double-positive cells into circulation was inhibited by EGCG. MMP-9 in the bone marrow is involved in mobilizing bone marrow-derived VEGFR-2 positive cells into peripheral circulation. Expression of MMP-9 mRNA was suppressed in bone marrow stromal cells by EGCG. In vivo model, EGCG reduced melanoma growth. Our study showed that EGCG specifically inhibits TEC and circulating EC through PI3K in EC and MMP-9 expression in bone marrow stroma. EGCG is a promising angiogenesis inhibitor for cancer therapy.

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 3432.

Abstract 2376: Endothelial cells acquire abnormalities by factors from tumor cells

Recently, it has been reported that tumor microenvironment is important for tumor progression and metastasis. We have reported that tumor endothelial cells (TECs) differ from their normal counterparts, in many aspects. For example, TECs upregulate several genes, have cytogenetical abnormalities and respond differently to the growth factors such as epidermal growth factor receptor (EGFR) or some anticancer drugs (Hida et al., Cancer Res 2004, Cancer Sci 2008). In this study, we focused on the interaction between tumor cells and endothelial cells to address the mechanism of TEC abnormality.

We demonstrate that cultured conditioned medium (CM) from melanoma cells cause several phenotypic changes in Human Microvascular Endothelial Cells (HMVEC). The cell proliferation of HMVEC was stimulated by melanoma CM. Furthermore, the expression level of Multi Drug Resistance Gene (MDR) was upregulated by melanoma CM treatment and HMVEC got less sensitive to Paclitaxel. It was suggested that some factors released from melanoma cause abmormalities in HMVEC phenotype. The study to elucidate mechanisms of these results are ongoing.

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 2376.