The Direct Oblique Method: A New Gold Standard for Bronchoscopic Navigation That is Superior to Automatic Methods.

BACKGROUND: The purpose of this study was to identify bronchi on computed tomographic (CT) images, manual analysis is more accurate than automatic methods. Nonetheless, manual bronchoscopic navigation is not preferred as it involves mentally reconstructing a route to a bronchial target by interpreting 2-dimensional CT images. Here, we established the direct oblique method (DOM), a form of manual bronchoscopic navigation that does not necessitate mental reconstruction, and compared it with automatic virtual bronchoscopic navigation (VBN). METHODS: Routes were calculated to 47 identical targets using 2 automatic VBNs (LungPoint and VINCENT-BFsim) and the DOM, using 3 general application CT viewers (Aquarius, Synapse Vincent, and OsiriX). Results of all analyses were compared. RESULTS: The DOM drew routes to more targets than the VBNs [94% (the DOM on any viewer) vs. 49% (LungPoint) vs. 62% (VINCENT-BFsim), P<0.0001]. For the 44 targets with the CT-bronchus or CT-artery signs, 100% of the DOM routes led to targets. In the bronchoscopic simulation phase, the DOM covered 100% of the bifurcations identified on CT, whereas some bifurcations were skipped and some bronchial walls appeared partially transparent in the VBNs. Manual analysis identified more bronchi near the targets than the VBNs [32.1±3.4 (manual analysis) vs.18.9±2.1 (LungPoint) vs. 22.9±2.7 (VINCENT-BFsim), mean±SEM, P<0.0001]. The DOM took around 5 minutes on average. CONCLUSION: On the basis of precise manual CT analysis using general application CT viewers, the DOM drew routes leading to more targets and provided better bronchoscopic simulation than the automatic route calculation of the VBNs.

TIMELESS is overexpressed in lung cancer and its expression correlates with poor patient survival.

TIMELESS (TIM) is a mammalian homolog of a Drosophila circadian rhythm gene, but its circadian properties in mammals have yet to be determined. TIM appears to be essential for replication protection and genomic stability. Recently, the involvement of TIM in human malignancies has been reported; therefore, we investigated the role of TIM in lung cancer. Microarray expression analysis of lung cancer cell lines showed that TIM expression was elevated 3.7-fold (P < 0.001) in non-small cell lung cancer cell lines (n = 116) compared to normal lung controls (n = 59). In addition, small cell lung cancer cell lines (n = 29) expressed TIM at levels 2.2-fold (P < 0.001) higher than non-small cell lung cancer. Western blot analysis of 22 lung cancer cell lines revealed that all of them expressed TIM protein and that 20 cell lines (91%) expressed TIM protein at higher levels than a normal control line. Remarkably, immunohistochemistry of 30 surgically resected lung cancer specimens showed that all lung cancer specimens but no matched normal lung tissues were positive for TIM expression. Moreover, immunohistochemistry of surgically resected specimens from 88 consecutive patients showed that high TIM protein levels correlated with poor overall survival (P = 0.013). Mutation analysis for TIM in 23 lung cancer cell lines revealed no mutation. TIM knockdown suppressed proliferation and clonogenic growth, and induced apoptosis in H157 and H460 cells. Taken together, our findings suggest that TIM could be useful as a diagnostic and prognostic marker for lung cancer and targeting it would be of high therapeutic value for this disease.

The circadian clock gene BMAL1 is a novel therapeutic target for malignant pleural mesothelioma.

Malignant pleural mesothelioma (MPM) is a highly aggressive neoplasm arising from the mesothelial cells lining the parietal pleura and it exhibits poor prognosis. Although there has been significant progress in MPM treatment, development of more efficient therapeutic approaches is needed. BMAL1 is a core component of the circadian clock machinery and its constitutive overexpression in MPM has been reported. Here, we demonstrate that BMAL1 may serve as a molecular target for MPM. The majority of MPM cell lines and a subset of MPM clinical specimens expressed higher levels of BMAL1 compared to a nontumorigenic mesothelial cell line (MeT-5A) and normal parietal pleural specimens, respectively. A serum shock induced a rhythmical BMAL1 expression change in MeT-5A but not in ACC-MESO-1, suggesting that the circadian rhythm pathway is deregulated in MPM cells. BMAL1 knockdown suppressed proliferation and anchorage-dependent and independent clonal growth in two MPM cell lines (ACC-MESO-1 and H290) but not in MeT-5A. Notably, BMAL1 depletion resulted in cell cycle disruption with a substantial increase in apoptotic and polyploidy cell population in association with downregulation of Wee1, cyclin B and p21(WAF1/CIP1) and upregulation of cyclin E expression. BMAL1 knockdown induced mitotic catastrophe as denoted by disruption of cell cycle regulators and induction of drastic morphological changes including micronucleation and multiple nuclei in ACC-MESO-1 cells that expressed the highest level of BMAL1. Taken together, these findings indicate that BMAL1 has a critical role in MPM and could serve as an attractive therapeutic target for MPM.

Transient but not stable ZEB1 knockdown dramatically inhibits growth of malignant pleural mesothelioma cells.

BACKGROUND: The role of ZEB1, a master epithelial-to-mesenchymal transition gene, in malignant pleural mesothelioma (MPM) is unclear. METHODS: The expression of ZEB1, E-cadherin, vimentin, and epithelial cell adhesion molecule (EpCAM) in 18 MPM cell lines and a normal pleural mesothelial cell line MeT-5A was determined by quantitative real-time polymerase chain reaction and Western blot testing. RNA interference-mediated transient and/or stable knockdown of ZEB1 and EpCAM was performed. Microarray expression analysis was performed with a TORAY-3D gene chip. Growth was evaluated by colorimetric proliferation and colony formation assays. Luciferase reporter assay was performed to access the effects of ZEB1 knockdown on EpCAM promoter activity. RESULTS: Most MPM cell lines exhibited mesenchymal phenotype and expressed ZEB1. Transient ZEB1 knockdown suppressed growth in all four cell lines studied (ACC-MESO-1, H2052, Y-MESO-8A, Y-MESO-29) while stable ZEB1 knockdown suppressed growth only in Y-MESO-29. Genome-wide gene expression analysis revealed that EpCAM was the most prominently up-regulated gene by both transient and stable ZEB1 knockdown in ACC-MESO-1, with more marked up-regulation in stable knockdown. We hypothesized that EpCAM up-regulation counteracts the stable ZEB1 knockdown-induced growth inhibition in ACC-MESO-1. Transient EpCAM knockdown suppressed growth dramatically in ACC-MESO-1 cells expressing shZEB1 but only modestly in those expressing shGFP, supporting our hypothesis. Luciferase reporter assay showed that ZEB1 knockdown resulted in increased EpCAM promoter activity. EpCAM was also up-regulated in Y-MESO-29 expressing shZEB1, but this EpCAM up-regulation did not counteract ZEB1knockdown-induced growth suppression, suggesting that the counteracting effects of EpCAM may be cellular context dependent. CONCLUSIONS: RNA interference-mediated ZEB1 knockdown may be a promising therapeutic strategy for MPM, but one has to consider the possibility of diminished growth inhibitory effects of long-term ZEB1 knockdown, possibly as a result of EpCAM up-regulation and/or other gene expression changes resulting from ZEB1 knockdown.

Pivotal role of epithelial cell adhesion molecule in the survival of lung cancer cells.

Epithelial cell adhesion molecule (EpCAM) is overexpressed in a wide variety of human cancers including lung cancer, and its contribution to increased proliferation through upregulation of cell cycle accelerators such as cyclins A and E has been well established in breast and gastric cancers. Nevertheless, very little is known about its role in supporting the survival of cancer cells. In addition, the functional role of EpCAM in the pathogenesis of lung cancer remains to be explored. In this study, we show that RNAi-mediated knockdown of EpCAM suppresses proliferation and clonogenic growth of three EpCAM-expressing lung cancer cell lines (H3255, H358, and HCC827), but does not induce cell cycle arrest in any of these. In addition, EpCAM knockdown inhibits invasion in the highly invasive H358 but not in less invasive H3255 cells in a Transwell assay. Of note, the EpCAM knockdown induces massive apoptosis in the three cell lines as well as in another EpCAM-expressing lung cancer cell line, HCC2279, but to a much lesser extent in a cdk4/hTERT immortalized normal human bronchial epithelial cell line, HBEC4, suggesting that EpCAM could be a therapeutic target for lung cancer. Finally, EpCAM knockdown partially restores contact inhibition in HCC827, in association with p27(Kip1) upregulation. These results indicate that EpCAM could contribute substantially to the pathogenesis of lung cancer, especially cancer cell survival, and suggest that EpCAM targeted therapy for lung cancer may have potential.

Knockdown of ZEB1, a master epithelial-to-mesenchymal transition (EMT) gene, suppresses anchorage-independent cell growth of lung cancer cells.

We found that among four master epithelial-to-mesenchymal transition (EMT)-inducing genes (ZEB1, SIP1, Snail, and Slug) ZEB1expression was most significantly correlated with the mesenchymal phenotype (high Vimentin and low E-cadherin expression) in non-small cell lung cancer (NSCLC) cell lines and tumors. Furthermore, ZEB1 knockdown with RNA interference in three NSCLC cell lines with high ZEB1 expression suppressed to varying degrees mass culture growth and liquid colony formation but in all cases dramatically suppressed soft agar colony formation. In addition, ZEB1 knockdown induced apoptosis in one of the three lines, indicating that the growth inhibitory effects of ZEB1 knockdown occurs in part through the activation of the apoptosis pathway. These results suggest that inhibiting ZEB1 function may be an attractive target for NSCLC therapeutic development.

Hepatoma-derived growth factor is induced in liver regeneration.

AIM: Hepatoma-derived growth factor (HDGF) is a heparin-binding protein, which has been suggested to be involved in the development of kidneys, the cardiovascular system and the liver. We have shown that HDGF is highly expressed in parenchymal hepatocytes in the developing liver and promotes fetal hepatocyte proliferation. In the present study, we asked whether HDGF expression was related to liver regeneration. METHODS: We examined the mRNA and protein expressions of HDGF in two liver regeneration models. In addition, cellular distribution of HDGF in the regenerating liver was investigated by immunohistochemistry. RESULTS: In the carbon tetrachloride (CCl(4))-treated liver, HDGF expression was induced and the peak was detected at 24 h after the CCl(4 )injection. HDGF expression was also enhanced in the hepatectomy model and the peak was detected at 12 h after surgery. The increased expression of HDGF protein was also confirmed by western blotting. Expression of the HDGF gene in the regenerating liver was dominantly detected in parenchymal hepatocytes. CONCLUSION: These findings showed that HDGF expression was induced in parenchymal hepatocytes before the DNA synthesis in the regenerating liver, suggesting the possible involvement of HDGF in liver regeneration as an autocrine factor.

[A case of pulmonary carcinosarcoma with pleural effusion, progressive pleural thickening and a calcification-like lesion].

A 70-year-old man was admitted to our hospital with dyspnea. Chest X-ray film revealed right pleural effusion. Chest CT showed right pleural effusion with slight pleural thickening and a patchy calcification-like lesion. Adenocarcinoma cells were detected in pleural effusion, but upper gastrointestinal endoscopy, barium enema examination and ultrasonography of the abdomen failed to show the primary lesion. We made a diagnosis of primary adenocarcinoma of the lung. Chemotherapy was performed after pleurodesis. However there was gradual increase of right pleural thickening and expansion of the calcification-like lesions. The patient died 16 months after his first visit. Pathological findings of the autopsy specimen revealed the tumor composed of an adenocarcinomatous component and an osteosarcomatous component. The final diagnosis was primary carcinosarcoma of the lung.

Partial blockage of hepatocyte maturation in hepatoma-derived growth factor transgenic mice.

AIM: To investigate the role of hepatoma-derived growth factor (HDGF) in liver development, especially in the hepatocyte differentiation. METHODS: We generated transgenic mice which overexpressed HDGF in hepatocytes under the transcriptional control of mouse albumin promoter/enhancer. To examine the effects of HDGF overexpression on hepatocyte differentiation, we investigated the expression patterns of the differentiation marker genes. RESULTS: The HDGF transgenic mice developed normally and showed no apparent abnormality in the liver. However, the gene expression patterns of the liver in adult transgenic mice were similar to those of the neonatal liver in control mice. CONCLUSION: These findings suggest that HDGF-overexpression partially suppresses hepatocyte maturation.

[A case of pulmonary inflammatory pseudotumor accompanied with increased serum immunoglobulin G levels and autoimmune pancreatitis].

A 77-year-old man with increased serum immunoglobulin G levels and autoimmune pancreatitis was found to have a chest X-ray abnormality. The chest X-ray and CT films showed a mass shadow in the right lower lobe and lymphadenopathy. Since transbronchial tumor biopsy did not obtain diagnostic material, CT-guided cutting needle biopsy was performed. The microscopic findings showed plasma cells and lymphocytes infiltrating the pleura and alveolar interstitium. A diagnosis of inflammatory pseudotumor was suspected, but it was difficult to exclude malignancy. Therefore, wedge resection of the right lower lobe including the mass and incisional biopsy of mediastinal lymph nodes were performed. Histopathologic examination of the resected specimen revealed inflammatory pseudotumor that was predominantly composed of mature plasma cells infiltrating in the bronchiolar wall, peribronchiolar interstitial tissue, alveolar wall, visceral pleura, the diaphragmatic area of the parietal pleura and mediastinal lymph nodes. Immunohistochemical staining revealed many IgG4-positive plasma cells diffusely infiltrated in the resected mass and lymph nodes. In this case, there is a possibility that patient developed autoimmune pancreatitis, pulmonary inflammatory pseudotumor and lymphadenopathy as part of systemic IgG4-related

Triple therapy of initial high-dose interferon with ribavirin and amantadine for patients with chronic hepatitis C.

AIMS: We previously reported the potential effect of combination therapy of an initial high-dose interferon (IFN) and amantadine on the eradication of HCV-RNA in patients with chronic hepatitis C. The additive effects of amantadine on interferon and ribavirin combination therapy remain controversial. In this study we investigated the efficacy of initial high-dose IFN with ribavirin and amantadine on the virological response in patients with chronic hepatitis C with a high viral load of genotype 1b. METHODS: Twenty-two patients with high viral loads of genotype 1b hepatitis C virus were enrolled in this pilot study. Patients were administered IFN-beta for four weeks and then IFN-alpha2b for 22 weeks with daily oral administration of ribavirin and amantadine. RESULTS: A sustained virological response (SVR) was shown in 31.8% (seven of 22 patients). With the naïve patients, the SVR rate was 21.4% (three of 14 patients). In patients who could not eradicate HCV-RNA by previous IFN monotherapy, the SVR rate was 50% (four of eight patients). CONCLUSION: Triple therapy with an initial high dose of IFN with ribavirin and amantadine may be effective, especially for chronic hepatitis C IFN-retreatment patients with a high viral load of genotype 1b.

Expression of hepatoma-derived growth factor is correlated with lymph node metastasis and prognosis of gastric carcinoma.

PURPOSE: Hepatoma-derived growth factor (HDGF) is a unique nuclear/growth factor and might play an important role in the development and progression of carcinomas. In the present study, association of HDGF expression with recurrence and prognosis of gastric carcinoma was examined. PATIENTS AND METHODS: HDGF expression in 317 patients with gastric carcinoma (233 males and 84 females) with ages ranging from 26 to 81 years (median, 60 years) was analyzed by immunohistochemistry. Samples with >90% of tumor cells to express positive immunoreactivity similar to or stronger than that in endothelial cells both for nucleus and cytoplasm were regarded as HDGF index level 2, and others as HDGF index level 1. RESULTS: One hundred and eighty-two cases showed level 1 HDGF expression, whereas 135 cases showed level 2 HDGF expression. Patients with level 2 expression showed higher rates of proximal tumor location (P < 0.0001), large tumor size (P < 0.0001), infiltrative tumor growth (P < 0.0001), presence of vascular and lymphatic invasion (P < 0.0001 for both), presence of lymph node metastasis (P < 0.0001), deep tumor invasion (P < 0.0001), and poorer disease-free and overall survival (P < 0.0001 for both) compared to those with level 1 expression. Multivariate analysis revealed HDGF expression level as an independent prognosticator for disease-free and overall survival. CONCLUSION: HDGF expression level was shown to be a prognostic factor for gastric carcinoma.

Hepatoma-derived growth factor is a novel prognostic factor for hepatocellular carcinoma.

BACKGROUND: Hepatoma-derived growth factor (HDGF) is involved in hepatocarcinogenesis, as well as in liver development and regeneration. This study investigated the correlation of HDGF expression with differentiation and prognosis of hepatocellular carcinoma (HCC). METHODS: HDGF expression in 100 patients with HCC (81 men and 19 women) with ages ranging from 34 to 81 years (median, 61 years) receiving surgical treatment was analyzed by immunohistochemistry. HDGF messenger RNA expression was evaluated in 10 cases by reverse transcription-polymerase chain reaction. The immunostaining pattern in HCCs was categorized as a positive HDGF index (showing positive staining in >90% of tumor cells in both nucleus and cytoplasm) or a negative HDGF index (all others). RESULTS: Twenty-seven cases (27%) showed a positive and 73 (73%) showed a negative HDGF index. HDGF messenger RNA expression was significantly higher in four cases with a positive HDGF index than in six with a negative index. Cases with well-differentiated histological characteristics showed a higher rate of positive HDGF index than those with a poorly differentiated subtype. Univariate and multivariate analysis revealed significantly poorer disease-free and overall survivals in patients with a positive HDGF index compared with patients with a negative index. CONCLUSIONS: These findings suggest the potential utility of HDGF immunohistochemistry in determining the prognosis of HCC.

[Palliation of malignant bile duct obstruction with metallic stent-clinical effectiveness in aged patients].

To evaluate the clinical effectiveness of metallic stent in the palliation of malignant bile duct obstruction in aged patients, 30 patients over 65 years of age with malignant biliary obstruction were investigated retrospectively. Overall survival duration after the stent placement was 13-1,275 (mean: 278, median: 169) days. The period of tube-free on the outpatient basis after stent insertion was 0-1,162 (mean: 192, median: 121) days. The estimated cost savings by eliminating hospitalization was greater than the stent cost. Four patients survived over 18 months despite their advanced clinical stages. It seems difficult to develop guidelines for the indication of stent placement in the treatment of malignant bile duct obstruction for aged patients.

[Three cases of transcatheter embolization for pulmonary arteriovenous fistula using detachable coils].

We report three cases of transcatheter embolization for pulmonary arteriovenous fistula (PAVF) using Interlocking detachable coils (IDC) and detachable fibered coils (DFC), and evaluate the outcome of transcatheter embolization with reference to previous reports. The three patients were women aged 56, 70 and 71 years. They had no symptoms, but chest radiographs were abnormal. None of them had Rendu-Osler-Weber disease. The three PAVFs were of the simple type, with a single feeding vessel and a single draining vein. In case 1, the feeding vessel arose from the left A4, while the feeding vessels in case 2 and 3 arose from the left A5. In case 1, we embolized the venous sac with detachable coils because the feeding vessel was short and kinked. In case 2 and 3, we embolized the feeding vessels closer as to the neck of the venous sac using detachable coils. The three PAVFs were all successfully embolized without severe complications, and transcatheter embolization seems to be an effective therapy.

Hepatoma-derived growth factor is a neurotrophic factor harbored in the nucleus.

Hepatoma-derived growth factor (HDGF) is a heparin-binding proliferating factor originally isolated from conditioned medium of the hepatoma-derived cell line HuH-7. HDGF has greatest homology in an amino acid sequence with high mobility group 1 (HMG1), which has been characterized as a DNA-binding, inflammatory, and potent neurite outgrowth molecule. HDGF is reported to be widely expressed and act as a growth factor in many kinds of cells. However, it has not been investigated in the nervous system. Here, we show by Western blot analysis that HDGF is present in the mouse brain from the embryonic period until adulthood. In situ hybridization and immunohistochemical analyses revealed that HDGF was expressed mainly in neurons, and HDGF protein was localized to the nucleus. HDGF and high mobility group 1 were secreted under physiological conditions and released extracellularly in necrotic conditions. Furthermore, we showed that exogenously supplied HDGF had a neurotrophic effect and was able to partially prevent the cell death of neurons in which endogenous HDGF was suppressed. Therefore, we propose that HDGF is a novel type of neurotrophic factor, on account of its localization in the nucleus and its potential to function in an autocrine manner under both physiological and pathological conditions throughout life.

Circulating auto-antibody against hepatoma-derived growth factor (HDGF) in patients with ulcerative colitis.

BACKGROUND/AIMS: Various circulating auto-antibodies have been reported in patients with ulcerative colitis. Hepatoma-derived growth factor (HDGF) is a mitogen, localized dominantly in the nucleus of proliferating cells. In this study, we demonstrated the circulating anti-HDGF auto-antibody and investigated its clinical roles in patients with ulcerative colitis. METHODOLOGY: Anti-HDGF IgG antibodies were measured by the enzyme-linked immunosorbent assay with recombinant HDGF in 20 healthy volunteers and 40 patients with ulcerative colitis. RESULTS: Circulating anti-HDGF antibody was detected in the serum of a patient with total colitis by Western blotting. Anti-HDGF auto-antibodies were detected at 65.6% in the serum of patients with total/left-sided colitis, compared with healthy subjects at 10%. During active stage, the circulating anti-HDGF auto-antibodies were detected at a higher frequency of 78.3% than those in remission stage at 37.5%. Furthermore, the titers during active colitis were higher than those during the remission stage. Anti-HDGF auto-antibodies were not detected in any patients with proctitis. CONCLUSIONS: These findings suggest that anti-HDGF auto-antibodies in the serum of patients with ulcerative colitis would help to classify the total/left-sided colitis from proctitis, and the serial measurement of the titer would also be a good marker for the active colitis.

Hepatoma-derived growth factor is involved in lung remodeling by stimulating epithelial growth.

Lung epithelial cells have an integral role in the maintenance of lung homeostasis; however, the regulatory mechanism thereof has not been fully clarified. Recently, hepatoma-derived growth factor (HDGF) was reported to be involved in organ development and remodeling through its mitogenic effect. We investigated the biological role of HDGF in lung remodeling. HDGF was more highly expressed in the lungs of idiopathic pulmonary fibrosis, chiefly in the epithelial cells, than in control nonfibrotic lungs. We also confirmed the expression of HDGF protein and mRNA in the lungs of bleomycin-instilled mice, mainly in the bronchial and alveolar epithelial cells, by immunohistochemical analysis and in situ hybridization. We found that recombinant HDGF promoted DNA synthesis in rat alveolar epithelial cells and A549 cells in vitro. Endogenous HDGF overexpressed by gene transfer was translocated into the nucleus and promoted the proliferation of A549 cells. In vivo intratracheal instillation of recombinant HDGF induced the proliferation of bronchial and alveolar epithelial cells without causing marked interstitial inflammation. These findings suggest that HDGF may be involved in lung remodeling after injury by promoting the proliferation of lung epithelial cells, probably in an autocrine manner.

A pilot study of combination therapy with initial high-dose interferon and amantadine hydrochloride for patients with chronic hepatitis C with the genotype 1b virus.

BACKGROUND/AIMS: Interferon monotherapy for patients with chronic hepatitis C has been suboptimal. We studied the effect of the combination therapy of an initial high-dose of interferon and amantadine. METHODOLOGY: We investigated the virological response of 20 patients with naive chronic hepatitis C with a high viral load of the genotype 1b virus. Seven patients were administered 6MU of interferon-beta once daily for 6 weeks and then thrice weekly for 20 weeks, and 13 were administered 6 MU of interferon-beta daily for 4 or 6 weeks and then 10 MU of natural interferon-alpha thrice weekly for 22 or 20 weeks. All patients were treated with amantadine hydrochloride (100 mg/day) for 26 weeks during interferon administration. RESULTS: The complete response, transient response and no response rate were 15.0%, 60.0%, and 25%, respectively. After daily administration of interferon-beta intravenously, 19 patients (95.0%) showed negative tests for serum HCV-RNA by the polymerase chain reaction method. At the end of treatment, the serum HCV-RNA was not detected in any patients treated with daily interferon-beta and intermittent interferon-alpha with amantadine. At 6-month follow-up, three patients had eradicated HCV-RNA, who were in the group of daily interferon-beta and intermittent interferon-alpha with amantadine. In the patients treated with daily interferon-beta and intermittent interferon-alpha with amantadine, the complete response, transient response and no response rates were 23.1%,-76.9% and 0%, respectively. CONCLUSIONS: These findings suggest that the combination of an initial high-dose interferon and amantadine shows promising effects on the eradication of HCV-RNA in the chronic hepatitis C patients with a high viral load of the genotype 1b virus.

Hepatoma-derived growth factor induces tumorigenesis in vivo through both direct angiogenic activity and induction of vascular endothelial growth factor.

Hepatoma-derived growth factor (HDGF) is highly expressed in tumor cells, and stimulates their proliferation. In the present study, we investigated the role of HDGF in tumorigenesis and elucidated the mechanism of action. Stable transfectants of NIH3T3 cells overexpressing HDGF did not show significant anchorage-independent growth in soft agar assay. However, these stable transfectants overexpressing HDGF generated sarcomatous tumors in nude mice. These tumors were red-colored macroscopically, and histologically showed a rich vascularity. Immunohistochemical analysis using CD31 antibody showed new vessel formation. Recombinant HDGF stimulated proliferation of human umbilical vein endothelial cells in a dose-dependent manner, and stimulated tubule formation. Furthermore, vascular endothelial growth factor (VEGF) was detected immunohistochemically in the tumor tissues. Transient expression of HDGF induced both VEGF gene and protein expression as demonstrated by a reporter assay using VEGF gene promoter. The administration of anti-VEGF neutralizing antibody significantly suppressed, but did not block, the tumor growth of HDGF-overexpressing cells in nude mice. Thus, these findings suggested that HDGF-induced tumor formation in vivo involves induction of VEGF as well as direct angiogenic activity.