Isolated Superior Oblique Muscle Swelling Causing Acute Vertical Strabismus in Graves' Disease.

PURPOSE: To report a case of isolated superior oblique muscle swelling causing acute vertical strabismus in Graves' disease. CASE: A 26-year-old woman with a 1-month history of misalignment of the right eye and diplopia was referred to us. Her visual acuity and intraocular pressures were normal in both eyes, but eye movement tests showed clear misalignment of her right eye. Antibody tests for myasthenia gravis were negative. However, blood tests revealed abnormal levels of thyroid-related factors, such as decreased thyroid-stimulating hormone, elevated free T3 and T4, and elevated anti-thyroid-stimulating hormone receptor antibody. We performed magnetic resonance imaging (MRI), which showed slight enlargement of the left superior oblique muscle. The patient was eventually diagnosed with Graves' disease with superior oblique muscle involvement and underwent a thyroidectomy. Three months postoperatively, her diplopia and abnormal eye movements had substantially resolved. CONCLUSION: Isolated superior oblique muscle involvement may be a presenting symptom of Graves' disease. It should be taken into consideration that, in the early stages of thyroid-associated ophthalmopathy (TAO) in adults, only the superior oblique muscle may be enlarged.

Corneal Perforation during Combination Chemotherapy including Cetuximab in a Patient with a History of Herpetic Keratitis.

PURPOSE: To report a case of corneal perforation, in a patient with a history of herpetic keratitis, during combination chemotherapy including cetuximab. CASE: We report the case of a 71-year-old man who was diagnosed with a hypopharyngeal carcinoma and received radiation therapy combined with cetuximab, the epidermal growth factor receptor (EGFR) inhibitor monoclonal antibody. He was referred to us because of ocular hyperemia and corneal perforation in his left eye. In spite of conservative therapy, his corneal perforation was exacerbated, with iris incarceration into the wound site and exposure to the surface of the cornea. He therefore discontinued treatment with the combination chemotherapy and underwent lamellar keratoplasty using a preserved donor cornea. After treatment with cetuximab resumed, there was no recurrence of the corneal perforation. CONCLUSION: We have presented the first case of cetuximab-related corneal perforation in a patient who had a history of recurrent herpetic keratitis. EGFR inhibitors, such as cetuximab, can induce corneal perforation in cases with a history of herpetic stromal keratitis.

Quantification of Eccentric Fixation Using Spectral-Domain Optical Coherence Tomography.

PURPOSE: This study aimed to evaluate the utility of optical coherence tomography (OCT) in the quantification of eccentric fixation in amblyopic patients. MATERIAL AND METHODS: In this study, 14 amblyopic patients and 10 healthy volunteers were enrolled. Under non-mydriatic conditions, fixation tests were performed directly using a fixation ophthalmoscope and indirectly using spectral-domain OCT. For evaluations using OCT, the distance between the fovea and the fixation point, which was determined by a cross-sectional image, was measured. RESULTS: On evaluations of healthy volunteers by OCT, the mean distance between the fixation point and the fovea was 80.4 ± 37.7 µm for the dominant eyes and 63.7 ± 36.4 µm for non-dominant eyes (p = 0.41). In amblyopic patients, on evaluation by OCT, the mean distance between the fixation point and the fovea was 193.8 ± 188.3 µm in amblyopic eyes and 83.5 ± 39.3 µm in paired fellow eyes (p = 0.02). Although OCT could detect eccentric fixation points in all the affected eyes of amblyopic patients, fixation ophthalmoscope was unable to quantify them in 2 of 14 affected eyes. CONCLUSIONS: Compared with a fixation ophthalmoscope, our method using OCT seems to be superior both in quantification and detection of eccentric fixation in amblyopic patients, without the need for mydriasis.

Neurotrophic Keratopathy after Trigeminal Nerve Block for Treatment of Postherpetic Neuralgia.

PURPOSE: To report a case of persistent corneal epithelial defect that had occurred after a trigeminal nerve block. CASE PRESENTATION: A 75-year-old female had suffered from postherpetic neuralgia for 8 years. She underwent Gasserian ganglion block surgery and noticed declining visual acuity in the right eye on the following day. She presented with severe hyperemia and corneal epithelial defects in the right eye and experienced remarkable reduction of sensitivity in the right cornea. She was diagnosed with neurotrophic keratopathy. Ofloxacin eye ointment and rebamipide ophthalmic suspension ameliorated the corneal epithelial defects but superficial punctate keratopathy, corneal superficial neovascularization, and Descemet's fold persisted. Although the epithelial defects occasionally recurred, the corneal sensation and epithelial defects, Descemet's fold, and corneal superficial neovascularization all improved around 5 months after trigeminal nerve block. The HRT II Rostock Cornea Module (RCM) could not detect any corneal subbasal nerve fibers at postoperative 4 months; however, it could detect them at postoperative 6 months. CONCLUSIONS: As the nerve block effect wore off, the corneal subbasal nerve fibers slowly regenerated. As the corneal sensation improved, the corneal epithelial defects and superficial neovascularization also improved. The HRT II RCM appeared useful for observing loss and regeneration of the corneal subbasal nerve fibers.

Extracellular Collagen Promotes Interleukin-1ß-Induced Urokinase-Type Plasminogen Activator Production by Human Corneal Fibroblasts.

Purpose: Keratocytes maintain homeostasis of the corneal stroma through synthesis, secretion, and degradation of collagen fibrils of the extracellular matrix. Given that these cells are essentially embedded in a collagen matrix, keratocyte-collagen interactions may play a key role in regulation of the expression or activation of enzymes responsible for matrix degradation including urokinase-type plasminogen activator (uPA), plasmin, and matrix metalloproteinases (MMPs). We examined the effect of extracellular collagen on the production of uPA by corneal fibroblasts (activated keratocytes) stimulated with the proinflammatory cytokine interleukin-1ß (IL-1ß). Methods: Human corneal fibroblasts were cultured either on plastic or in a three-dimensional gel of type I collagen. Plasminogen activators were detected by fibrin zymography, whereas the IL-1 receptor (IL-1R) and MMPs were detected by immunoblot analysis. Collagen degradation by corneal fibroblasts was assessed by measurement of hydroxyproline in acid hydrolysates of culture supernatants. Results: Collagen and IL-1ß synergistically increased the synthesis and secretion of uPA in corneal fibroblasts. Collagen also upregulated IL-1R expression in the cells in a concentration-dependent manner. The conversion of extracellular plasminogen to plasmin, as well as the plasminogen-dependent activation of MMP-1 and MMP-3 and degradation of collagen apparent in three-dimensional cultures of corneal fibroblasts exposed to IL-1ß, were all abolished by a selective uPA inhibitor. Conclusions: Collagen and IL-1ß cooperate to upregulate uPA production by corneal fibroblasts. Furthermore, IL-1ß-induced collagen degradation by these cells appears to be strictly dependent on uPA expression and mediated by a uPA-plasmin-MMP pathway.

Impact of Tight Junction Protein ZO-1 and TWIST Expression on Postoperative Survival of Patients with Hepatocellular Carcinoma.

BACKGROUND: Epithelial-mesenchymal transition (EMT) is considered to play a critical role in cancer progression and metastasis. However, the impact of EMT on the prognosis of hepatocellular carcinoma (HCC) is still elusive. In this study, we examined the relationship between the expression of EMT markers and recurrence-free survival (RFS) and overall survival (OS) in HCC patients after hepatic resection. SUMMARY: The mRNA expression of 15 genes related to EMT was assessed by quantitative real-time polymerase chain reaction in cancerous tissues from 72 patients who underwent hepatic resection of HCC between January 2005 and December 2010 at our hospital. The upregulation of TWIST and the downregulation of tight junction protein ZO-1 (TJP1) were significantly associated with shorter RFS as well as OS. Increased levels of TWIST and decreased levels of TJP1 should be predictive markers for poor prognosis in patients with HCC after hepatectomy; those could serve as potential biomarkers for the treatment of HCC. Key Messages: A low level of TJP1 and high level of TWIST expression were prognostic factors predicting HCC after hepatic resection.

The roles of urokinase-type plasminogen activator in leukocyte infiltration and inflammatory responses in mice corneas treated with lipopolysaccharide.

PURPOSE: Urokinase-type plasminogen activator (u-PA) plays an important role in corneal wound healing, yet its role in corneal inflammation remains poorly understood. We investigated the role of u-PA in a murine model of lipopolysaccharide (LPS)-induced corneal inflammation. METHODS: The corneal epithelium was scraped and LPS was applied to u-PA wild-type (u-PA(+/+)) and u-PA-deficient (u-PA(-/-)) mice. Corneal re-epithelialization and opacity were measured by stereomicroscopy. Fibrin zymography was performed to detect plasminogen activators in corneas from u-PA(+/+) and u-PA(-/-) mice. Neutrophil, macrophage, and u-PA receptor (u-PAR) expression were determined by immunohistochemistry. Gene expression of corneal macrophage chemoattractant protein (MCP)-1 and macrophage inflammatory protein (MIP)-2 was assessed with reverse transcription-polymerase chain reaction. The in vitro effects of endogenous u-PA on MCP-1, MIP-2, matrix metalloproteinase (MMP)-2, and MMP-9 expression, and macrophage migration activity in mouse ocular fibroblasts stimulated by LPS, were examined. RESULTS: The u-PA(+/+) mice showed enhanced corneal inflammation as compared with u-PA(-/-) mice. The u-PA expression was increased by LPS stimulation. Immunohistochemical analyses indicated that more neutrophils and macrophages were present in corneas from u-PA(+/+) mice than u-PA(-/-) mice. The u-PAR expression was detected in inflammatory cells and in the leading edges of the epithelial migrating cells. Enhanced mRNA expression of MCP-1 and MIP-2 was observed in corneas from u-PA(+/+) mice compared to u-PA(-/-) mice. Macrophage chemoattractant protein-1, MIP-2, and MMP-9, but not MMP-2, significantly increased in corneal fibroblasts from u-PA(+/+) mice compared with u-PA(-/-) mice. CONCLUSIONS: These data indicate that u-PA promotes LPS-induced leukocyte infiltration in cornea and that u-PA is an important component in LPS-induced corneal inflammatory responses.

Slug increases sensitivity to tubulin-binding agents via the downregulation of ßIII and ßIVa-tubulin in lung cancer cells.

Transcription factor Slug/SNAI2 (snail homolog 2) plays a key role in the induction of the epithelial mesenchymal transition in cancer cells; however, whether the overexpression of Slug mediates the malignant phenotype and alters drug sensitivity in lung cancer cells remains largely unclear. We investigated Slug focusing on its biological function and involvement in drug sensitivity in lung cancer cells. Stable Slug transfectants showed typical morphological changes compared with control cells. Slug overexpression did not change the cellular proliferations; however, migration activity and anchorage-independent growth activity with an antiapoptotic effect were increased. Interestingly, stable Slug overexpression increased drug sensitivity to tubulin-binding agents including vinorelbine, vincristine, and paclitaxel (5.8- to 8.9-fold increase) in several lung cancer cell lines but did not increase sensitivity to agents other than tubulin-binding agents. Real-time RT-PCR (polymerase chain reaction) and western blotting revealed that Slug overexpression downregulated the expression of ßIII and ßIVa-tubulin, which is considered to be a major factor determining sensitivity to tubulin-binding agents. A luciferase reporter assay confirmed that Slug suppressed the promoter activity of ßIVa-tubulin at a transcriptional level. Slug overexpression enhanced tumor growth, whereas Slug overexpression increased drug sensitivity to vinorelbine with the downregulation of ßIII and ßIV-tubulin in vivo. Immunohistochemistry of Slug with clinical lung cancer samples showed that Slug overexpression tended to be involved in response to tubulin-binding agents. In conclusion, our data indicate that Slug mediates an aggressive phenotype including enhanced migration activity, anoikis suppression, and tumor growth, but increases sensitivity to tubulin-binding agents via the downregulation of ßIII and ßIVa-tubulin in lung cancer cells.

Slug is upregulated during wound healing and regulates cellular phenotypes in corneal epithelial cells.

PURPOSE: The involvement of the epithelial mesenchymal transition (EMT) in the process of corneal wound healing remains largely unclear. The purpose of the present study was to gain insight into Slug expression and corneal wound healing. METHODS: Slug expression during wound healing in the murine cornea was evaluated using fluorescence staining in vivo. Slug or Snail was stably introduced into human corneal epithelial cells (HCECs). These stable transfectants were evaluated for the induction of the EMT, cellular growth, migration activity, and expression changes in differentiation-related molecules. RESULTS: Slug, but not Snail, was clearly expressed in the nuclei of corneal epithelial cells in basal lesion of the corneal epithelium during wound healing in vivo. The overexpression of Slug or Snail induced an EMT-like cellular morphology and cadherin switching in HCECs, indicating that these transcription factors were able to mediate the typical EMT in HCECs. The overexpression of Slug or Snail suppressed cellular proliferation but enhanced the migration activity. Furthermore, ABCG2, TP63, and keratin 19, which are known as stemness-related molecules, were downregulated in these transfectants. CONCLUSIONS: It was found that Slug is upregulated during corneal wound healing in vivo. The overexpression of Slug mediated a change in the cellular phenotype affecting proliferation, migration, and expression levels of differentiation-related molecules. This is the first evidence that Slug is regulated during the process of corneal wound healing in the corneal epithelium in vivo, providing a novel insight into the EMT and Slug expression in corneal wound healing.

SRPX2 is a novel chondroitin sulfate proteoglycan that is overexpressed in gastrointestinal cancer.

SRPX2 (Sushi repeat-containing protein, X-linked 2) has recently emerged as a multifunctional protein that is involved in seizure disorders, angiogenesis and cellular adhesion. Here, we analyzed this protein biochemically. SRPX2 protein was secreted with a highly posttranslational modification. Chondroitinase ABC treatment completely decreased the molecular mass of purified SRPX2 protein to its predicted size, whereas heparitinase, keratanase and hyaluroinidase did not. Secreted SRPX2 protein was also detected using an anti-chondroitin sulfate antibody. These results indicate that SRPX2 is a novel chondroitin sulfate proteoglycan (CSPG). Furthermore, a binding assay revealed that hepatocyte growth factor dose-dependently binds to SRPX2 protein, and a ligand-glycosaminoglycans interaction was speculated to be likely in proteoglycans. Regarding its molecular architecture, SRPX2 has sushi repeat modules similar to four other CSPGs/lecticans; however, the molecular architecture of SRPX2 seems to be quite different from that of the lecticans. Taken together, we found that SRPX2 is a novel CSPG that is overexpressed in gastrointestinal cancer cells. Our findings provide key glycobiological insight into SRPX2 in cancer cells and demonstrate that SRPX2 is a new member of the cancer-related proteoglycan family.

Integrated analysis of whole genome exon array and array-comparative genomic hybridization in gastric and colorectal cancer cells.

Whole genome-scale integrated analyses of exon array and array-comparative genomic hybridization are expected to enable the identification of unknown genetic features of cancer cells. Here, we evaluated this approach in 22 gastric and colorectal cancer cell lines, focusing on protein kinase genes and genes belonging to the cadherin-catenin family. Regarding alternative splicing patterns, several cancer cell lines predominantly expressed isoform 1 of protein kinase A catalytic subunit beta (PRKACB). Paired gastric cancer specimens demonstrated that isoform 1 of PRKACB was a novel cancer-related variant transcript in gastric cancers. In addition, the exon array analysis clearly identified exon 3 or exon 3-4 skipping in catenin beta 1, a short intron insertion with exon 9 skipping in CDH1, and a deletional transcript of CDH13. These abnormal transcripts were shown to have arisen from small genomic deletions. Meanwhile, an integrated analysis of 11 gastric cancer cell lines revealed that four cell lines amplified fibroblast growth factor receptor 2, with truncated forms observed in two of the cell lines. Gene amplification, and not the truncated form, was found to determine the sensitivity to a fibroblast growth factor receptor inhibitor, indicating that our cell line panel might be useful for cell-based evaluations of specific inhibitors. Using an integrated analysis, we identified several abnormal transcripts and genomic alterations in gastric and colorectal cancer cells. Our approach might enable genetic changes to be identified more efficiently, and the present results warrant further investigation using clinical samples and integrated analyses.

Aza-derivatives of resveratrol are potent macrophage migration inhibitory factor inhibitors.

Resveratrol (3, 4', 5-trihydroxy-trans-stilbene), a natural phytoalexin found in grapes and wine, has anti-proliferative activity on human-derived cancer cells. In our study, we used a conventional condensation reaction between aldehydes and amines to provide a number of aza-resveratrol (3, 4', 5-trihydroxy-trans- aza-stilbene) derivatives in an attempt to screen for compounds with resveratrol's action but with increased potency. Aza-resveratrol and its hydroxylated derivative (3, 4, 4', 5-tetrahydroxy-trans- aza-stilbene) showed a more enhanced anti-proliferative effect than resveratrol in an MCF-7 breast carcinoma cell line. To identify the cellular targets of the aza derivatives of resveratrol, we conjugated the latter aza-stilbene compound with epoxy-activated agarose and performed affinity purification. Macrophage migration inhibitory factor (MIF), a proinflammatory cytokine, was identified as a major target protein in MCF-7 cell lysates using a matrix-assisted laser desorption/ionization time-of-flight mass spectrometer (MALDI-TOF MS). The aza-resveratrol and its hydroxylated derivative, but not resveratrol, were also found to be potent inhibitors of MIF tautomerase activity, which may be associated with their inhibitory effects on MIF bioactivity for cell growth.

Acquired drug resistance to vascular endothelial growth factor receptor 2 tyrosine kinase inhibitor in human vascular endothelial cells.

Acquired resistance to antiangiogenic drugs has emerged as a potentially important issue in clinical settings; however, the underlying molecular and cellular mechanism of resistance to vascular endothelial growth factor receptor 2 (VEGFR2) tyrosine kinase inhibitor (TKI) remains largely unclear. We evaluated the cellular characteristics of human umbilical vein endothelial cell (HUVEC) clones, which are resistant to VEGFR2-TKI (Ki8751) to elucidate this mechanism of resistance to antiangiogenic drugs. Resistant HUVEC clones were 10-fold more resistant to VEGFR2-TKI than the parental cells and they exhibited an almost complete absence of VEGF-mediated cellular proliferation. The mRNA expression analysis revealed that expression of VEGFR1, VEGFR2 and VEGFR3 was lower in resistant clones, while that of several angiogenic ligands was increased. The protein expression of VEGFR2 was markedly down-regulated in two (R5 and R6 clone) out of five resistant clones. Focusing on the R5 clone, VEGF stimulation did not increase the phosphorylation of VEGFR2 or the dimerization of VEGFR2. The inhibition of phospho-AKT by VEGFR2-TKI was also weakened more than 10-fold in the R5 clone. Finally, a microarray analysis revealed that some angiogenesis-associated, and some angiogenesis-specific genes, including platelet endothelial cell adhesion molecule 1 (PECAM1)/CD31, homeobox A9 (HOXA9), and endothelial cell-specific molecule 1 (ESM1), were remarkably down-regulated in all the resistant clones compared with the parental cells. HUVEC clones resistant to VEGFR2-TKI exhibited down-regulation of VEGFR2, a decreased signal response to VEGF stimulation, and the loss of vascular endothelial markers. These results strongly suggest that an escape from VEGFR2 signaling-dependency is one of the cellular mechanisms of resistance to VEGFR2-TKI in vascular endothelial cells.

Sorafenib inhibits the hepatocyte growth factor-mediated epithelial mesenchymal transition in hepatocellular carcinoma.

The epithelial mesenchymal transition (EMT) has emerged as a pivotal event in the development of the invasive and metastatic potentials of cancer progression. Sorafenib, a VEGFR inhibitor with activity against RAF kinase, is active against hepatocellular carcinoma (HCC); however, the possible involvement of sorafenib in the EMT remains unclear. Here, we examined the effect of sorafenib on the EMT. Hepatocyte growth factor (HGF) induced EMT-like morphologic changes and the upregulation of SNAI1 and N-cadherin expression. The downregulation of E-cadherin expression in HepG2 and Huh7 HCC cell lines shows that HGF mediates the EMT in HCC. The knockdown of SNAI1 using siRNA canceled the HGF-mediated morphologic changes and cadherin switching, indicating that SNAI1 is required for the HGF-mediated EMT in HCC. Interestingly, sorafenib and the MEK inhibitor U0126 markedly inhibited the HGF-induced morphologic changes, SNAI1 upregulation, and cadherin switching, whereas the PI3 kinase inhibitor wortmannin did not. Collectively, these findings indicate that sorafenib downregulates SNAI1 expression by inhibiting mitogen-activated protein kinase (MAPK) signaling, thereby inhibiting the EMT in HCC cells. In fact, a wound healing and migration assay revealed that sorafenib completely canceled the HGF-mediated cellular migration in HCC cells. In conclusion, we found that sorafenib exerts a potent inhibitory activity against the EMT by inhibiting MAPK signaling and SNAI1 expression in HCC. Our findings may provide a novel insight into the anti-EMT effect of tyrosine kinase inhibitors in cancer cells.

Antitumor activity of BIBF 1120, a triple angiokinase inhibitor, and use of VEGFR2+pTyr+ peripheral blood leukocytes as a pharmacodynamic biomarker in vivo.

PURPOSE: BIBF 1120 is a potent, orally available triple angiokinase inhibitor that inhibits VEGF receptors (VEGFR) 1, 2, and 3, fibroblast growth factor receptors, and platelet-derived growth factor receptors. This study examined the antitumor effects of BIBF 1120 on hepatocellular carcinoma (HCC) and attempted to identify a pharmacodynamic biomarker for use in early clinical trials. EXPERIMENTAL DESIGN: We evaluated the antitumor and antiangiogenic effects of BIBF 1120 against HCC cell line both in vitro and in vivo. For the pharmacodynamic study, the phosphorylation levels of VEGFR2 in VEGF-stimulated peripheral blood leukocytes (PBL) were evaluated in mice inoculated with HCC cells and treated with BIBF 1120. RESULTS: BIBF 1120 (0.01 µmol/L) clearly inhibited the VEGFR2 signaling in vitro. The direct growth inhibitory effects of BIBF 1120 on four HCC cell lines were relatively mild in vitro (IC(50) values: 2-5 µmol/L); however, the oral administration of BIBF 1120 (50 or 100 mg/kg/d) significantly inhibited the tumor growth and angiogenesis in a HepG2 xenograft model. A flow cytometric analysis revealed that BIBF 1120 significantly decreased the phosphotyrosine (pTyr) levels of VEGFR2(+)CD45(dim) PBLs and the percentage of VEGFR2(+)pTyr(+) PBLs in vivo; the latter parameter seemed to be a more feasible pharmacodynamic biomarker. CONCLUSIONS: We found that BIBF 1120 exhibited potent antitumor and antiangiogenic activity against HCC and identified VEGFR2(+)pTyr(+) PBLs as a feasible and noninvasive pharmacodynamic biomarker in vivo.

TGF-ß induces sustained upregulation of SNAI1 and SNAI2 through Smad and non-Smad pathways in a human corneal epithelial cell line.

PURPOSE: The aim of this study was to investigate the expression changes of epithelial mesenchymal transition (EMT)-related molecules induced by TGF-ß signaling in a human corneal epithelial cell line (HCECs). METHODS: The cellular response to TGF-ß was evaluated by immunoblotting, quantitative real-time RT-PCR, and immunofluorescence microscopy in HCECs. RESULTS: TGF-ß significantly increased mRNA expression of SNAI1, SNAI2, VIM, and FN1, but not TWIST1 through Smad and non-Smad pathways in HCECs. Protein expression of a mesenchymal marker N-cadherin was dose-dependently increased and that of an epithelial marker of E-cadherin was decreased by TGF-ß. TGF-ß, but not EGF, mediated the EMT-like morphologic changes. Both TGF-ß and EGF were capable of upregulating SNAI1 and SNAI2 by about two-fold within a short response time. However, a detailed time course analysis revealed drastically different expression patterns, with TGF-ß mediating a sustained upregulation of SNAI1 and SNAI2 for at least for 6 days and EGF allowing a return to the baseline expression values after 8 ∼ 12 h. These data indicate that TGF-ß, but not EGF, induces sustained upregulation of SNAI1 and SNAI2 in HCECs. CONCLUSIONS: TGF-ß induces sustained upregulation of SNAI1 and SNAI2 through Smad and non-Smad pathways, EMT-like morphologic changes, downregulation of E-cadherin, and upregulation of N-cadherin in HCECs. The authors' findings provide insight into the TGF-ß signaling and the temporal expression patterns of EMT-inducible transcription factors in HCECs.

Bortezomib potentially inhibits cellular growth of vascular endothelial cells through suppression of G2/M transition.

Bortezomib, a selective 26S proteasome inhibitor, has shown clinical benefits against refractory multiple myeloma. The indirect anti-angiogenic activity of bortezomib has been widely recognized; however, the growth-inhibitory mechanism of bortezomib on vascular endothelial cells remains unclear, especially on the cell cycle. Here, we showed that bortezomib (2 nM of the IC(50) value) potently inhibited the cellular growth of human umbilical vascular endothelial cells (HUVECs) via a vascular endothelial growth factor receptor (VEGFR)-independent mechanism resulting in the induction of apoptosis. Bortezomib significantly increased the vascular permeability of HUVECs, whereas a VEGFR-2 tyrosine kinase inhibitor decreased it. Interestingly, a cell cycle analysis using flow cytometry, the immunostaining of phospho-histone H3, and Giemsa staining revealed that bortezomib suppressed the G2/M transition of HUVECs, whereas the mitotic inhibitor paclitaxel induced M-phase accumulation. A further analysis of cell cycle-related proteins revealed that bortezomib increased the expression levels of cyclin B1, the cdc2/cyclin B complex, and the phosphorylation of all T14, Y15, and T161 residues on cdc2. Bortezomib also increased the ubiquitination of cyclin B1 and wee1, but inhibited the kinase activity of the cdc2/cyclin B complex. These protein modifications support the concept that bortezomib suppresses the G2/M transition, rather than causing M-phase arrest. In conclusion, we demonstrated that bortezomib potently inhibits cell growth by suppressing the G2/M transition, modifying G2/M-phase-related cycle regulators, and increasing the vascular permeability of vascular endothelial cells. Our findings reveal a cell cycle-related mode of action and strongly suggest that bortezomib exerts an additional unique vascular disrupting effect as a vascular targeting drug.

FOXQ1 is overexpressed in colorectal cancer and enhances tumorigenicity and tumor growth.

Forkhead box Q1 (FOXQ1) is a member of the forkhead transcription factor family, and it has recently been proposed to participate in gastric acid secretion and mucin gene expression in mice. However, the role of FOXQ1 in humans and especially in cancer cells remains unknown. We found that FOXQ1 mRNA is overexpressed in clinical specimens of colorectal cancer (CRC; 28-fold/colonic mucosa). A microarray analysis revealed that the knockdown of FOXQ1 using small interfering RNA resulted in a decrease in p21(CIP1/WAF1) expression, and a reporter assay and a chromatin immunoprecipitation assay showed that p21 was one of the target genes of FOXQ1. Stable FOXQ1-overexpressing cells (H1299/FOXQ1) exhibited elevated levels of p21 expression and inhibition of apoptosis induced by doxorubicin or camptothecin. Although cellular proliferation was decreased in H1299/FOXQ1 cells in vitro, H1299/FOXQ1 cells significantly increased tumorigenicity [enhanced green fluorescent protein (EGFP): 2/15, FOXQ1: 7/15] and enhanced tumor growth (437 +/- 301 versus 1735 +/- 769 mm3, P < 0.001) in vivo. Meanwhile, stable p21 knockdown of H1299/FOXQ1 cells increased tumor growth, suggesting that FOXQ1 promotes tumor growth independent of p21. Microarray analysis of H1299/EGFP and H1299/FOXQ1 revealed that FOXQ1 overexpression upregulated several genes that have positive roles for tumor growth, including VEGFA, WNT3A, RSPO2, and BCL11A. CD31 and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling staining of the tumor specimens showed that FOXQ1 overexpression mediated the angiogenic and antiapoptotic effect in vivo. In conclusion, FOXQ1 is overexpressed in CRC and enhances tumorigenicity and tumor growth presumably through its angiogenic and antiapoptotic effects. Our findings show that FOXQ1 is a new member of the cancer-related FOX family.

mTOR signal and hypoxia-inducible factor-1 alpha regulate CD133 expression in cancer cells.

The underlying mechanism regulating the expression of the cancer stem cell/tumor-initiating cell marker CD133/prominin-1 in cancer cells remains largely unclear, although knowledge of this mechanism would likely provide important biological information regarding cancer stem cells. Here, we found that the inhibition of mTOR signaling up-regulated CD133 expression at both the mRNA and protein levels in a CD133-overexpressing cancer cell line. This effect was canceled by a rapamycin-competitor, tacrolimus, and was not modified by conventional cytotoxic drugs. We hypothesized that hypoxia-inducible factor-1 alpha (HIF-1 alpha), a downstream molecule in the mTOR signaling pathway, might regulate CD133 expression; we therefore investigated the relation between CD133 and HIF-1 alpha. Hypoxic conditions up-regulated HIF-1 alpha expression and inversely down-regulated CD133 expression at both the mRNA and protein levels. Similarly, the HIF-1 alpha activator deferoxamine mesylate dose-dependently down-regulated CD133 expression, consistent with the effects of hypoxic conditions. Finally, the correlations between CD133 and the expressions of HIF-1 alpha and HIF-1 beta were examined using clinical gastric cancer samples. A strong inverse correlation (r = -0.68) was observed between CD133 and HIF-1 alpha, but not between CD133 and HIF-1 beta. In conclusion, these results indicate that HIF-1 alpha down-regulates CD133 expression and suggest that mTOR signaling is involved in the expression of CD133 in cancer cells. Our findings provide a novel insight into the regulatory mechanisms of CD133 expression via mTOR signaling and HIF-1 alpha in cancer cells and might lead to insights into the involvement of the mTOR signal and oxygen-sensitive intracellular pathways in the maintenance of stemness in cancer stem cells.