Bovine Lactoferrin Suppresses Tumor Angiogenesis through NF-κB Pathway Inhibition by Binding to TRAF6

Tumor angiogenesis is essential for tumor progression. The inhibition of tumor angiogenesis is a promising therapy for tumors. Bovine lactoferrin (bLF) has been reported as an anti-tumor agent. However, bLF effects on tumor angiogenesis are not well demonstrated. This study evaluated the inhibitory effects of bLF on tumor angiogenesis in vivo and in vitro. Herein, tumor endothelial cells (TECs) and normal endothelial cells (NECs) were used. Proliferation, migration, tube formation assays, RT-PCR, flow cytometry, Western blotting, siRNA experiments and immunoprecipitation were conducted to clarify the mechanisms of bLF-induced effects. CD-31 immunoexpression was examined in tumor tissues of oral squamous cell carcinoma mouse models with or without Liposomal bLF (LbLF)-administration. We confirmed that bLF inhibited proliferation/migration/tube formation and increased apoptosis in TECs but not NECs. TNF receptor-associated factor 6 (TRAF6), p-p65, hypoxia inducible factor-α (HIF-1α) and vascular endothelial growth factor (VEGF) were highly expressed in TECs. In TECs, bLF markedly downregulated VEGF-A, VEGF receptor (VEGFR) and HIF-1α via the inhibition of p-p65 through binding with TRAF6. Since NECs slightly expressed p-p65, bLF-TRAF-6 binding could not induce detectable changes. Moreover, orally administrated LbLF decreased CD31-positive microvascular density only in TECs. Hence, bLF specifically suppressed tumor angiogenesis through p-p65 inhibition by binding to TRAF6 and suppressing HIF-1α activation followed by VEGF/VEGFR down-regulation. Collectively, bLF can be an anti-angiogenic agent for tumors.

Correlation between endothelial CXCR7 expression and clinicopathological factors in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) impairs functionality and sensuousness resulting in poor quality of life. Biomarkers can predict disease trajectory and lead to effective treatments. Transcriptomics have identified genes that are upregulated in tumor endothelial cells (TECs) compared with normal endothelial cells (NECs). Among them, chemokine receptor 7 (CXCR7) is highly expressed in TECs of several cancers and involved in angiogenesis of TECs. However, levels of CXCR7 in OSCC blood vessels have not been fully investigated. In this study, we analyzed the correlation between CXCR7 expression in TECs and clinicopathological factors in OSCC. Immunohistochemistry for CXCR7 and CD34 was performed on 59 OSCC tissue specimens resected between 1996 and 2008 at Hokkaido University Hospital. CXCR7 expression in blood vessels was evaluated by the ratio of CXCR7+/CD34+ blood vessels. CXCR7 expression was 42% and 19% in tumor and non-tumor parts, respectively, suggesting that CXCR7 expression is higher in TECs than in NECs. CXCR7 expression in TECs correlated with advanced T-stage and cancer stage. Overall survival and disease-free survival rates were higher in low-expressing CXCR7 patients than in high-expressing. These results suggest that CXCR7 expression in blood vessels may be a useful diagnostic and prognostic marker for OSCC patients.

Patients with SATB2-associated syndrome exhibiting multiple odontomas

Special AT-rich sequence-binding protein 2 (SATB2)-associated syndrome (SAS) is characterized by alterations of SATB2. Its clinical features include intellectual disability and craniofacial abnormalities, such as cleft palate, dysmorphic features, and dental abnormalities. Here, we describe three previously undiagnosed, unrelated patients with SAS who exhibited dental abnormalities, including multiple odontomas. Although isolated odontomas are common, multiple odontomas are rare. Individuals in families 1 and 3 underwent whole-exome sequencing. Patient 2 and parents underwent targeted amplicon sequencing. On the basis of the hg19/GRCh37 reference and the RefSeq mRNA NM_001172517, respective heterozygous mutations were found and validated in Patients 1, 2, and 3: a splice-site mutation (chr2:g.200137396C > T, c.1741-1G > A), a nonsense mutation (chr2:g.200213750G > A, c.847C > T, p.R283*), and a frame-shift mutations (chr2:g.200188589_200188590del, c.1478_1479del, p.Q493Rfs*19). All mutations occurred de novo. The mutations in Patients 1 and 3 were novel; the mutation in Patient 2 has been described previously. Tooth mesenchymal cells derived from Patient 2 showed diminished SATB2 expression. Multiple odontomas were evident in the patients in this report; however, this has not been recognized previously as a SAS-associated phenotype. We propose that multiple odontomas be considered as an occasional manifestation of SAS.

HuR translocation to the cytoplasm of cancer cells in actin-independent manner

Human antigen R (HuR) is a RNA-binding protein, which binds to the AU-rich element (ARE) in the 3'-untranslated region (3'-UTR) of certain mRNA and is involved in the export and stabilization of ARE-mRNA. HuR constitutively relocates to the cytoplasm in many cancer cells, however the mechanism of intracellular HuR trafficking is poorly understood. To address this question, we examined the functional role of the cytoskeleton in HuR relocalization. We tested the effect of actin depolymerizing macrolide latrunculin A or myosin II ATPase activity inhibitor blebbistatin for HuR relocalization induced by the vasoactive hormone Angiotensin II in cancer and control normal cells. Western blot and confocal imaging data revealed that both inhibitors attenuated the cytoplasmic HuR in normal cells but no such alteration was observed in cancer cells. Concomitant with changes in intracellular HuR localization, both inhibitors markedly decreased the accumulation and half-lives of HuR target ARE-mRNAs in normal cells, whereas no change was observed in cancer cells. Furthermore, co-immunoprecipitation experiments with HuR proteins revealed clear physical interaction with ß-actin only in normal cells. The current study is the first to verify that cancer cells can implicate a microfilament independent HuR transport. We hypothesized that when cytoskeleton structure is impaired, cancer cells can acquire an alternative HuR trafficking strategy.

ROS enhance angiogenic properties via regulation of NRF2 in tumor endothelial cells

Reactive oxygen species (ROS) are unstable molecules that activate oxidative stress. Because of the insufficient blood flow in tumors, the tumor microenvironment is often exposed to hypoxic condition and nutrient deprivation, which induces ROS accumulation. We isolated tumor endothelial cells (TECs) and found that they have various abnormalities, although the underlying mechanisms are not fully understood. Here we showed that ROS were accumulated in tumor blood vessels and ROS enhanced TEC migration with upregulation of several angiogenesis related gene expressions. It was also demonstrated that these genes were upregulated by regulation of Nuclear factor erythroid 2-related factor 2 (NRF2). Among these genes, we focused on Biglycan, a small leucine-rich proteoglycan. Inhibition of Toll-like receptors 2 and 4, known BIGLYCAN (BGN) receptors, cancelled the TEC motility stimulated by ROS. ROS inhibited NRF2 expression in TECs but not in NECs, and NRF2 inhibited phosphorylation of SMAD2/3, which activates transcription of BGN. These results indicated that ROS-induced BGN caused the pro-angiogenic phenotype in TECs via NRF2 dysregulation.

Adenovirus infection induces HuR relocalization to facilitate virus replication

HuR is an RNA-binding protein of the embryonic lethal abnormal vision (ELAV) family, which binds to the AU-rich element (ARE) in the 3'-untranslated region (UTR) of certain mRNAs and is involved in the nucleo-cytoplasmic export and stabilization of ARE-mRNAs. The cytoplasmic relocalization of ARE-mRNAs with several proteins such as HuR and pp32 increases in cells transformed by the adenovirus oncogene product E4orf6. Additionally, these ARE-mRNAs were stabilized and acquired the potential to transform cells. Although, the relocalization of HuR and the stabilization of ARE-mRNAs are crucial for cell transformation, evidence regarding the relationship of HuR and ARE-mRNAs with adenovirus replication is lacking. In this report, we demonstrate that adenovirus infection induces the relocation of HuR to the cytoplasm of host cells. Analysis using the luciferase-ARE fusion gene and the tetracycline (tet)-off system revealed that the process of stabilizing ARE-mRNAs is activated in adenovirus-infected cells. Heat shock treatment or knockdown-mediated depletion of HuR reduced adenovirus production. Furthermore, expression of ARE-including viral IVa2 mRNA, decreased in HuR-depleted infected cells. These results indicate that HuR plays an important role in adenovirus replication, at least in part, by up-regulating IVa2 mRNA expression and that ARE-mRNA stabilization is required for both transformation and virus replication.

miR-145 promoted anoikis resistance in tumor endothelial cells

Tumor progression is dependent on tumor angiogenesis. We previously reported that the phenotype of tumor endothelial cells (TECs) is distinct from normal endothelial cells (NECs). Herein, we conducted a pathway analysis using a public TEC microarray database and identified several putative TEC-specific miRNAs. We found that miR-145 expression was upregulated in TECs and that miR-145 enhanced cell adhesion and anoikis resistance and upregulated Bcl-2 and Bcl-xl via ERK1/2 in human microvascular endothelial cells. These findings suggested that miR-145 is involved in the acquisition of the TEC phenotype, partially. Therefore, miR-145 and its target genes may be molecular targets for anti-angiogenic therapy.

Tumor endothelial cells with high aldehyde dehydrogenase activity show drug resistance

Tumor blood vessels play an important role in tumor progression and metastasis. We previously reported that tumor endothelial cells (TEC) exhibit several altered phenotypes compared with normal endothelial cells (NEC). For example, TEC have chromosomal abnormalities and are resistant to several anticancer drugs. Furthermore, TEC contain stem cell‐like populations with high aldehyde dehydrogenase (ALDH) activity (ALDH^highTEC). ALDH^highTEC have proangiogenic properties compared with ALDH^lowTEC. However, the association between ALDH^highTEC and drug resistance remains unclear. In the present study, we found that ALDH mRNA expression and activity were higher in both human and mouse TEC than in NEC. Human NEC:human microvascular endothelial cells (HMVEC) were treated with tumor‐conditioned medium (tumor CM). The ALDH^high population increased along with upregulation of stem‐related genes such as multidrug resistance 1, CD90, ALP, and Oct‐4. Tumor CM also induced sphere‐forming ability in HMVEC. Platelet‐derived growth factor (PDGF)‐A in tumor CM was shown to induce ALDH expression in HMVEC. Finally, ALDH^highTEC were resistant to fluorouracil (5‐FU) in vitro and in vivo. ALDH^highTEC showed a higher grade of aneuploidy compared with that in ALDH^lowTEC. These results suggested that tumor‐secreting factor increases ALDH^highTEC populations that are resistant to 5‐FU. Therefore, ALDH^highTEC in tumor blood vessels might be an important target to overcome or prevent drug resistance.

Induction of Calcification in MC3T3-E1 Cells by Inorganic Polyphosphate

Relatively large amounts of inorganic polyphosphate [poly(P)] (400 μM) have been found in normal osteoblasts. The effect of poly(P) with an average chain length of 65 phosphate residues on cell calcification was therefore investigated with the use of MC3T3-E1 cells. Expression of both osteopontin and osteocalcin was induced by poly(P) (0.1 ~ 1 mM), and cells treated with poly(P) were strongly stained by alizarin red. In addition, the level of alkaline phosphatase activity induced in poly(P)-treated cells was two-fold higher than that in either orthophosphate-treated or control cells but not higher than that in cells treated with β-glycerophosphate and ascorbic acid. In contrast, however, polyphosphatase activities were activated by poly(P) treatment to levels up to six-fold greater than that in controls. MC3T3-E1 cells may utilize poly(P) as a phosphate source for calcification rather than phosphate sources that are mainly produced by ALPase. Poly(P)-dependent induction of polyphosphatase activities may therefore promote calcification in MC3T3-E1 cells.

ALDH1 and podoplanin expression patterns predict the risk of malignant transformation in oral leukoplakia

Oral leukoplakia (OL) is a clinically diagnosed preneoplastic lesion of the oral cavity with an increased oral cancer risk. However, the risk of malignant transformation is still difficult to assess. The objective of the present study was to examine the expression patterns of aldehyde dehydrogenase 1 (ALDH1) and podoplanin in OL, and to determine their roles in predicting oral cancer development. In the present study, the expression patterns of ALDH1 and podoplanin were determined in samples from 79 patients with OL. The association between protein expression and clinicopathological parameters, including oral cancer-free survival, was analyzed during a mean follow-up period of 3.4 years. Expression of ALDH1 and podoplanin was observed in 61 and 67% patients, respectively. Kaplan-Meier analysis demonstrated that the expression of the proteins was correlated with the risk of progression to oral cancer. Multivariate analysis revealed that expression of ALDH1 and podoplanin was associated with 3.02- and 2.62-fold increased risk of malignant transformation, respectively. The malignant transformation risk of OL was considerably higher in cases with expression of both proteins. Point-prevalence analysis revealed that 66% of patients with co-expression of ALDH1 and podoplanin developed oral cancer. Taken together, our data indicate that ALDH1 and podoplanin expression patterns in OL are associated with oral cancer development, suggesting that ALDH1 and podoplanin may be useful biomarkers to identify OL patients with a substantially high oral cancer risk.

HuR and podoplanin expression is associated with a high risk of malignant transformation in patients with oral preneoplastic lesions

The risk of malignant transformation in oral preneoplastic lesions (OPLs) is challenging to assess. The objective of the present study was to determine the expression of ELAV like RNA binding protein 1 (HuR) and podoplanin in OPLs, and to evaluate the use of each protein as biomarkers for the risk assessment of malignant transformations. Immunohistochemistry for HuR and podoplanin was performed on the tissues of 51 patients with OPL, including cases of low grade dysplasia (LGD) and high grade dysplasia (HGD). The association between the protein expression patterns and clinicopathological parameters, including oral cancer free survival (OCFS) time, was analyzed during the follow-up period. HuR and podoplanin expression was observed in 28 (55%) and 36 (71%) of 51 patients, respectively. Kaplan-Meier analysis showed that the expression of HuR and podoplanin was associated with the risk of progression to oral cancer (P<0.05). Multivariate analysis revealed that HuR and podoplanin expression was associated with a 2.93-fold (95% confidence interval (CI), 0.98–10.34; P=0.055) and 2.06-fold (95% CI, 0.55–8.01; P=0.283) increase in risk of malignant transformation, respectively. The risk of OPL malignant transformation was considerably increased with the coexpression of HuR and podoplanin compared with the histological grading (95% CI, 1.64–23.59; P=0.005). The results of the present study demonstrated that the expression of HuR and podoplanin associates with malignant transformation and suggests that the proteins may be used as biomarkers to identify OPL patients with an increased risk of cancer development.

Abstract 1513: ALDH1 and podoplanin expression in oral leukoplakia: Correlate with malignant transformaion risk

Oral leukoplakia (OL) is the clinically diagnosed preneoplastic lesion in the oral cavity with an increased oral cancer risk. However, the risk of malignant transformation of OL is still difficult to assess. The objective of this study was to examine the expression patterns of ALDH1 and Podoplanin (PD) and determine their role in predicting oral cancer development in patients with OL. In a retrospective follow-up study, the expression patterns of ALDH1 and PD were determined using immunohistochemistry in samples from 79 patients with OL, including patients with untransformed lesions (n = 42) and patients with malignant transformed lesions (n = 37). The association between protein expression patterns and clinicopathologic parameters including oral cancer free survival (OCFS) was analyzed during a mean follow up period of 3.5 years. ALDH1 and PD expression was observed in 48 (61%) and 53 (67%) patients respectively. Kaplan-Meier analysis showed that the expression of ALDH1 and PD was correlated with the risk of progression to oral cancer (P = &lt; 0.05). Multivariate analysis revealed that ALDH1 and PD expression was associated with 3.02 folds and 2.62 folds of increase risk of malignant transformation, respectively. Meanwhile, the malignant transformation risk of OL was considerably higher in cases with both ALDH1 and PD expression (P = 0.000). Taken together, our data indicated that ALDH1 and PD expression patterns in OL were associated with oral cancer development, suggesting that ALDH1 and PD could be useful biomarkers to identify OL patient with substantially high oral cancer risk.

Citation Format: Umma Habiba, Masanobu Shindoh. ALDH1 and podoplanin expression in oral leukoplakia: Correlate with malignant transformaion risk. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1513. doi:10.1158/1538-7445.AM2015-1513

CXCL12-CXCR7 axis is important for tumor endothelial cell angiogenic property

We reported that tumor endothelial cells (TECs) differ from normal endothelial cells (NECs) in many aspects, such as gene expression profiles. Although CXCR7 is reportedly highly expressed in blood vessels of several tumors, its function in TECs is still unknown. To investigate this role, we isolated TECs from mouse tumor A375SM xenografts, and compared them with NECs from normal mouse dermis. After confirming CXCR7 upregulation in TECs, we analyzed its function using CXCR7 siRNA and CXCR7 inhibitor; CCX771. CXCR7 siRNA and CCX771 inhibited migration, tube formation and resistance to serum starvation in TECs but not in NECs. ERK1/2 phosphorylation was inhibited by CXCR7 knockdown in TECs. These results suggest that CXCR7 promotes angiogenesis in TECs via ERK1/2 phosphorylation. Using ELISA, we also detected CXCL12, a ligand of CXCR7, in conditioned medium from TECs, but not from NECs. CXCL12 neutralizing antibody significantly inhibited TEC random motility. VEGF stimulation upregulated CXCR7 expression in NECs, implying that VEGF mediates CXCR7 expression in endothelial cells. A CXCR7 inhibitor, CCX771 also inhibited tumor growth, lung metastasis and tumor angiogenesis in vivo. Taken together, the CXCL12-CXCR7 autocrine loop affects TEC proangiogenic properties, and could be the basis for an antiangiogenic therapy that specifically targets tumor blood vessels rather than normal vessels.

Identification of tumor endothelial cells with high aldehyde dehydrogenase activity and a highly angiogenic phenotype

Tumor blood vessels play an important role in tumor progression and metastasis. It has been reported that tumor endothelial cells (TECs) exhibit highly angiogenic phenotypes compared with those of normal endothelial cells (NECs). TECs show higher proliferative and migratory abilities than those NECs, together with upregulation of vascular endothelial growth factor (VEGF) and VEGF receptor 2 (VEGFR2). Furthermore, compared with NECs, stem cell markers such as Sca-1, CD90, and multidrug resistance 1 are upregulated in TECs, suggesting that stem-like cells exist in tumor blood vessels. In this study, to reveal the biological role of stem-like TECs, we analyzed expression of the stem cell marker aldehyde dehydrogenase (ALDH) in TECs and characterized ALDHhigh TECs. TECs and NECs were isolated from melanoma-xenografted nude mice and normal dermis, respectively. ALDH mRNA expression and activity were higher in TECs than those in NECs. Next, ALDHhigh/low TECs were isolated by fluorescence-activated cell sorting to compare their characteristics. Compared with ALDHlow TECs, ALDHhigh TECs formed more tubes on Matrigel-coated plates and sustained the tubular networks longer. Furthermore, VEGFR2 expression was higher in ALDHhigh TECs than that in ALDHlow TECs. In addition, ALDH was expressed in the tumor blood vessels of in vivo mouse models of melanoma and oral carcinoma, but not in normal blood vessels. These findings indicate that ALDHhigh TECs exhibit an angiogenic phenotype. Stem-like TECs may have an essential role in tumor angiogenesis.

Suprabasin as a novel tumor endothelial cell marker

Recent studies have reported that stromal cells contribute to tumor progression. We previously demonstrated that tumor endothelial cells (TEC) characteristics were different from those of normal endothelial cells (NEC). Furthermore, we performed gene profile analysis in TEC and NEC, revealing that suprabasin (SBSN) was upregulated in TEC compared with NEC. However, its role in TEC is still unknown. Here we showed that SBSN expression was higher in isolated human and mouse TEC than in NEC. SBSN knockdown inhibited the migration and tube formation ability of TEC. We also showed that the AKT pathway was a downstream factor of SBSN. These findings suggest that SBSN is involved in the angiogenic potential of TEC and may be a novel TEC marker.

Anti-BP180-type mucous membrane pemphigoid: report of two cases

We describe two patients with anti-BP180-type mucous membrane pemphigoid (MMP), who were correctly diagnosed and treated in early stages through the cooperation of dentists and dermatologists. Patient 1 was a 74-year-old woman who visited our dental department due to blisters over the oral mucosa and eruptions on the skin. She had also experienced bleeding of the gingiva and palate mucosa. Biopsy specimens from the oral mucosa revealed detachment of epithelial basement membrane and subepithelial lamina propria with slight chronic inflammation. Direct immunofluorescence (DIF) revealed linear IgG and IgA deposits along the basement membrane zone (BMZ). Indirect immunofluorescence (IIF) using 1 M-NaCl split normal human skin showed binding of IgG and IgA on the epidermal side. On immunoblot analysis, IgG and IgA autoantibodies reacted with the C-terminal protein of BP180. These findings indicated a diagnosis of anti-BP180-type MMP. Patient 2 was a 59-year-old woman who was referred to our dental department with a history of blisters and large erosions on the gingiva. Biopsy specimens from the oral mucosa revealed partial junctional separation at the level of the basement membrane. DIF showed linear depositions of IgG and C3 along the BMZ. IIF, using 1 M-NaCl split normal human skin, revealed circulating anti-BMZ-IgG antibodies bound to the epidermal side. These findings indicated a diagnosis of anti-BP180-type MMP. Both patients were treated successfully with systemic or topical steroids and oral health care. In conclusion, appropriate clinical examination and cooperation among medical specialists are important for the early diagnosis and treatment of patients with recurrent and chronic stomatitis and for their good prognosis.

Cytoplasmic expression of HuR may be a valuable diagnostic tool for determining the potential for malignant transformation of oral verrucous borderline lesions

Oral verrucous carcinoma (OVC) is a low grade variant of oral squamous cell carcinoma, and oral verrucous hyperplasia (OVH) is a benign lesion without malignant features. However, pathologists are sometimes presented with borderline lesions and are indecisive as to diagnose them as benign or malignant. Thus, these lesions are tentatively termed oral verrucous lesions (OVLs). HuR is an ARE mRNA-binding protein, normally localized in the nucleus but cytoplasmic exportation is frequently observed in cancer cells. The present study aimed to elucidate whether expression of the HuR protein facilitates the diagnosis of true malignant lesions. Clinicopathological features were evaluated, and immunohistochemical analysis for p53, Ki67 and HuR proteins was performed in 48 cases of OVH, OVC and OVL, and the outcomes were correlated using appropriate statistical analysis. The association of these three proteins in relation to malignant transformation was analyzed after a 3-year follow-up of 25 OVL cases. The basal characteristics (age, gender and location) of all cases had no significant association with the types of lesions. Gingiva (39.4%) was the common site for all lesions. Distribution of the examined proteins had a significant association with the lesions. As compared with the OVLs, the number of immunostained-positive cells was significantly higher in the OVCs and lower in the OVH cases. During follow-up, 24% of the OVLs underwent malignant transformation for which high HuR expression and a diffuse staining pattern in the epithelium were observed. Taken together, the high degree of HuR expression with diffuse staining pattern in the epithelium may be an effective diagnostic tool that determines the potential of OVLs for malignant transformation.

pp32r1 controls the decay of the RNA-binding protein HuR

pp32 is a tumor suppressor and is one of the associated proteins of the RNA-binding protein HuR. The pp32-HuR complex is exported to the cytoplasm of cells under stress conditions, and HuR is degraded by caspases in the cytoplasm. In the present study, we examined the role of pp32r1, a member of the pp32 family that has oncogenic properties, in the decay of HuR. pp32r1 was found to be abundantly expressed in cancer cells, and overexpression of pp32r1 induced colony formation in soft-agar. pp32r1 was expressed in both the nucleus and cytoplasm, whereas pp32 was predominantly localized in the nucleus. Even with lethal stress such as staurosporine (STS), HuR in the cytoplasm was never downregulated, and caspase-3 activity was inhibited when cells expressed pp32r1. pp32r1 bound to HuR without interacting with pp32. In cancer cells, HuR survived in the cytoplasm of cells overexpressing pp32r1, although HuR was not expressed in the cytoplasm of pp32-expressing cells, similar to lethal stress conditions. Taken together, these results indicate that pp32r1 binds to HuR to avoid the caspase-mediated decay of HuR in the cytoplasm of cells. We suggest that this function contributes to the oncogenic activity of pp32r1.

Hypoxia-induced reactive oxygen species cause chromosomal abnormalities in endothelial cells in the tumor microenvironment

There is much evidence that hypoxia in the tumor microenvironment enhances tumor progression. In an earlier study, we reported abnormal phenotypes of tumor-associated endothelial cells such as those resistant to chemotherapy and chromosomal instability. Here we investigated the role of hypoxia in the acquisition of chromosomal abnormalities in endothelial cells. Tumor-associated endothelial cells isolated from human tumor xenografts showed chromosomal abnormalities, >30% of which were aneuploidy. Aneuploidy of the tumor-associated endothelial cells was also shown by simultaneous in-situ hybridization for chromosome 17 and by immunohistochemistry with anti-CD31 antibody for endothelial staining. The aneuploid cells were surrounded by a pimonidazole-positive area, indicating hypoxia. Human microvascular endothelial cells expressed hypoxia-inducible factor 1 and vascular endothelial growth factor A in response to either hypoxia or hypoxia-reoxygenation, and in these conditions, they acquired aneuploidy in 7 days. Induction of aneuploidy was inhibited by either inhibition of vascular endothelial growth factor signaling with vascular endothelial growth factor receptor 2 inhibitor or by inhibition of reactive oxygen species by N-acetyl-L-cysteine. These results indicate that hypoxia induces chromosomal abnormalities in endothelial cells through the induction of reactive oxygen species and excess signaling of vascular endothelial growth factor in the tumor microenvironment.

18F-fluoromisonidazole PET uptake is correlated with hypoxia-inducible factor-1α expression in oral squamous cell carcinoma

Hypoxia is a common feature of cancer and a prognostic factor for many types of cancer. (18)F-fluoromisonidazole ((18)F-FMISO) PET can detect tumor hypoxia noninvasively. Hypoxia-inducible factor-1 (HIF-1) is a key player in the transcriptional response to low oxygen tension in many types of cancer. Its activity is mainly dependent on the stability and modification of HIF-1α, which is a composition of HIF-1. However, it is unclear whether (18)F-FMISO PET can identify HIF-1α expression in oral squamous cell carcinoma (OSCC). The present study was performed to elucidate the correlation between (18)F-FMISO PET findings and HIF-1α expression in OSCC.

METHODS

Twenty-three patients (age range, 42-84 y; 15 men, 8 women) with OSCC were enrolled in this study. The T-stages of cancer were T1 in 1 patient, T2 in 9, T3 in 2, and T4a in 11. The N-stages were N0 in 13 patients, N1 in 5, and N2 in 5. Each patient underwent (18)F-FMISO and (18)F-FDG PET before surgery, and the maximum standardized uptake value (SUV max) of both PET studies was measured. HIF-1α expression in the operation materials was evaluated by immunohistochemical staining. The SUV max of both PET studies and HIF-1α findings were compared statistically.

RESULTS

(18)F-FMISO PET detected uptake in the primary site in 14 of the 23 patients (61%). The median SUV max of (18)F-FMISO and (18)F-FDG PET in the primary site was 1.83 (range, 0.8-2.7) and 16.5 (range, 1.0-32.3), respectively. There was a weak significant correlation between (18)F-FMISO and (18)F-FDG PET SUV max (P = 0.02, r = 0.48). HIF-1α expression was clearly detected in 11 of the 23 patients (48%). The (18)F-FMISO PET SUV max was significantly higher in the HIF-1α-positive cases than in the HIF-1α-negative cases (median, 2.1; range, 1.5-2.4, vs. median, 1.6; range, 0.8-2.0, respectively) (P = 0.002). However, there were no significant correlations between (18)F-FDG PET SUV max and HIF-1α expression (median, 21.8; range, 7.7-29.1 vs. 1.0-32.2) (P = 0.06).

CONCLUSION

(18)F-FMISO uptake in the primary site of OSCC indicates a hypoxic environment with HIF-1α expression.

Expression of parathyroid hormone-related protein confers malignant potential to mucoepidermoid carcinoma

Parathyroid hormone-related protein (PTHrP) is known to induce bone resorption by activating RANKL as well as PTH. PTHrP plays a central role in humoral hypercalcemia, and its expression has been reported to be closely associated with bone metastasis of breast carcinoma. PTHrP expression in oral squamous carcinoma cell lines was investigated, and PTHrP was expressed in oral squamous cell carcinoma cell lines similar to that in a prostate carcinoma cell line. Mucoepidermoid carcinoma is the most common malignant salivary gland tumor composed of different types of cells including a squamous component. Its clinical behavior is highly variable and ranges from slow-growing and indolent to locally aggressive and highly metastatic. We examined the PTHrP expression in mucoepidermoid carcinoma and assessed the significance of its correlation with clinicopathological features. Immunohistochemical detection of PTHrP was carried out in 21 cases of mucoepidermoid carcinoma in the head and neck region. PTHrP was highly detectable in intermediate and epidermoid cells, and abundant expression of PTHrP in intermediate cells had a significant association with cancer malignancy, including lymph node metastasis and/or tumor recurrence. These results suggest that PTHrP expression can be used as a prognostic factor for mucoepidermoid carcinoma.

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.