Downregulation of microRNA-224-3p Hampers Retinoblastoma Progression via Activation of the Hippo-YAP Signaling Pathway by Increasing LATS2.

Purpose: The pivotal role of microRNAs (miRNAs or miRs) has been proved in the pathogenesis of retinoblastoma. miR-224-3p is demonstrated to be involved in several tumors. However, the underlying mechanism of miR-224-3p in retinoblastoma is yet to be investigated. Therefore, this study was designed to identify the regulation of miR-224-3p in human retinoblastoma. Methods: The expression pattern of miR-224-3p and large tumor suppressor 2 (LATS2) in retinoblastoma was measured by reverse transcription quantitative polymerase chain reaction. Afterward, the interaction between miR-224-3p and LATS2 was identified using a dual luciferase reporter gene assay. Next, gain-of-function and loss-of-function approaches were employed to examine the effects of miR-224-3p and LATS2 as well as their interaction on cell apoptosis, proliferation and angiogenesis abilities, and tumorigenesis. Whether the Hippo-YAP signaling pathway was involved in tumorigenesis was analyzed by determining downstream genes. Results: LATS2 was downregulated in retinoblastoma, and its overexpression promoted apoptosis and suppressed proliferation of retinoblastoma cells. miR-224-3p, highly expressed in retinoblastoma, inhibited the expression of its target gene LATS2, which inhibited activation of the Hippo-YAP signaling pathway. Suppression of miR-224-3p promoted apoptosis while suppressing the proliferation of retinoblastoma cells and angiogenesis. Tumor progression induced by upregulation of miR-224-3p was diminished by restoration of LATS2. It was observed that tumor growth and angiogenesis were reduced by depleted miR-224-3p in the animal experiments. Conclusions: The present study suggests that miR-224-3p targets LATS2 and blocks the Hippo-YAP signaling pathway activation, thus preventing the progression of retinoblastoma, which could be a new therapeutic target for retinoblastoma.

Effectively suppressed angiogenesis-mediated retinoblastoma growth using celastrol nanomicelles.

Celastrol, a Chinese herbal medicine, has already shown an inhibition effect on retinoblastoma growth activity in our previous research, but its mechanism is not well understood. Angiogenesis is a main driving force in many tumors. Here, we studied whether celastrol could inhibit angiogenesis-mediated retinoblastoma growth, if so, through what mechanism. In this work, we developed celastrol-loaded polymeric nanomicelles to improve the poor water solubility of celastrol. When given an intraperitoneal injection to mice bearing human retinoblastoma xenografts, celastrol nanomicelles (CNMs, 27.2 mg/kg/2 days) significantly reduced the weight and the volume of tumors and decreased tumor angiogenesis. We found that CNMs suppressed hypoxia-induced proliferation, migration, and invasion by human umbilical vascular endothelial cells (EA.hy 926) in a dose-dependent manner. Furthermore, CNMs inhibited SO-Rb 50 cells-induced sprouting of the vessels and vascular formation in chick embryo chorioallantoic membrane assay in vitro. To understand the molecular mechanism of these activities, we assessed the signaling pathways in CoCl2 treated EA.hy 926. CNMs inhibited the hypoxia-induced HIF-1α and VEGF. In conclusion, our results reveal that CNMs target the HIF-1α/VEGF pathway, which may be an important reason for the suppression of retinoblastoma growth and angiogenesis.

Temsirolimus as a dual inhibitor of retinoblastoma and angiogenesis via targeting mTOR signalling.

Targeting the mammalian target of rapamycin (mTOR) is a promising strategy for cancer therapy. Temsirolimus, a FDA-approved anticancer drug with efficacy in certain solid tumors and hematologic malignancies, is a potent mTOR inhibitor. In this work, we are the first to provide preclinical evidence that temsirolimus is an attractive candidate for retinoblastoma treatment as a dual inhibitor of retinoblastoma and angiogenesis. We show that temsirolimus selectively inhibits growth, survival and migration of retinoblastoma cells while sparing normal retinal and fibroblast cells, with IC50 value that is within the clinically achievable range. Temsirolimus potently inhibits retinal angiogenesis via targeting biological functions of retinal endothelial cells. Our mechanism analysis demonstrates that temsirolimus inhibits retinoblastoma and angiogenesis via suppressing mTOR signalling and secretion of proangiogenic cytokines. In line with in vitro data, we further demonstrate the inhibitory effects of temsirolimus on retinoblastoma and angiogenesis in in vivo xenograft mouse model. Our findings provide a preclinical rationale to explore temsirolimus as a strategy to treat retinoblastoma and highlight the therapeutic value of targeting mTOR in retinoblastoma.

Overexpression of microRNA-186 inhibits angiogenesis in retinoblastoma via the Hedgehog signaling pathway by targeting ATAD2.

Retinoblastoma (RB) represents an aggressive malignancy in the eye during the period of infancy and childhood. We delineated the ability of microRNA-186 (miR-186) to influence viability, invasion, migration, angiogenesis, and apoptosis of RB via the Hedgehog signaling pathway by targeting AAA domain-containing protein 2 (ATAD2). The microarray-based analysis was adopted to identify differentially expressed genes (DEGs) related to RB. Subsequently, RB cells were treated with miR-186 mimic, miR-186 inhibitor, or si-ATAD2. The expression of miR-186, ATAD2, Hedgehog signaling pathway-related genes were evaluated, and the target relationship between miR-186 and ATAD2 was verified. Finally, cell proliferation, invasion, migration, apoptosis, and angiogenesis were assessed. ATAD2 was identified as a DEG and modulated by miR-186. Moreover, we revealed that ATAD2 was highly expressed, whereas miR-186 was lowly expressed, and the Hedgehog signaling pathway was activated in RB. Then, ATAD2 as a putative target of miR-186 was validated using a luciferase assay. miR-186 mimic or siRNA-ATAD2 in RB cells reduced cell viability, invasion, and migration coordinating with elevated apoptosis via impairing the Hedgehog signaling pathway, where repressed angiogenesis was observed. Overexpression of miR-186 attenuates RB via the inactivation of the Hedgehog signaling pathway by downregulating ATAD2.

INTRAVITREAL ANTI-VASCULAR ENDOTHELIAL GROWTH FACTOR FOR THE MANAGEMENT OF NEOVASCULARIZATION IN RETINOBLASTOMA AFTER INTRAVENOUS AND/OR INTRAARTERIAL CHEMOTHERAPY: Long-Term Outcomes in a Series of 35 Eyes.

PURPOSE: To report the use of anti-vascular endothelial growth factor in the management of retinoblastoma. METHODS: Retrospective review of 35 eyes (33 patients) treated with at least one intravitreal anti-vascular endothelial growth factor (ranibizumab and/or aflibercept) for new iris (n = 26) and/or retinal neovascularization (n = 21) after intravenous chemotherapy and/or intraarterial chemotherapy. RESULTS: Most eyes (n = 31/35, 89%) were Group D or E. Previous treatments were salvage intraarterial chemotherapy after intravenous chemotherapy (n = 21/35, 60%), first-line intraarterial chemotherapy (n = 7/35, 20%), and first-line intravenous chemotherapy (n = 7/35, 20%). Associated clinical features were retinal ischemia (94%), retinal detachment (51%), active tumor (34%), intravitreal hemorrhage (43%), and/or glaucoma (17%). Mean 1.6 anti-vascular endothelial growth factor injections/eye were given; 28 eyes received ranibizumab, 2 aflibercept, and 5 both agents. Eight eyes underwent complementary treatments of ischemic retina. Resolution of neovascularization was observed in 28 eyes (n = 28/35, 80%). Globe salvage was achieved in 51% (n = 18/35), including 25% of those with active tumor (n = 3/12). One eye became phthisic. Sixteen eyes were enucleated, nine for tumor relapse/progression. Five eyes had high-risk histopathologic risk factors and received adjuvant intravenous chemotherapy. All patients are alive with no extraocular extension nor metastases (mean follow-up 3.7 years, range 1.1-7.6). CONCLUSION: Intravitreal anti-vascular endothelial growth factor contributed to a globe salvage rate of 51% by providing conditions to continue conservative treatment.

Efficacy and safety of aflibercept in in vitro and in vivo models of retinoblastoma.

BACKGROUND: To evaluate the inhibitory effects of aflibercept on the growth and subretinal invasion of retinoblastoma. METHODS: Xenotransplantation and orthotopic mouse models were created by injecting Y-79 cells subcutaneously and intravitreally, respectively. After induction of retinoblastoma, animals were intraperitoneally injected with aflibercept (25 mg/kg body weight) or saline twice a week for 3 weeks. Tumor size was measured weekly and compared between the two groups. At 4 weeks, animals were sacrificed and an immunohistochemical examination was conducted to compare the microvascular density and degree of apoptosis between groups. In addition, the degree of choroidal invasion was also analyzed in the orthotopic xenotransplantation model. A co-culture system of Y-79 or WERI-Rb-1 cells and human umbilical vein endothelial cells (HUVECs) was used for in vitro experiments, and the anti-angiogenic effect of aflibercept was evaluated by analyzing cell numbers. RESULTS: In the Y-79 xenotransplantation model, aflibercept treatment significantly inhibited tumor growth at 4 weeks versus baseline compared with saline-injected mice (188.53 ± 118.53 mm3 vs. 747.87 ± 118.83 mm3, respectively, P < 0.001). Tumors isolated from aflibercept-treated mice contained fewer blood vessels (8.59 % ± 7.60 % vs. 14.91 % ± 4.53 %, respectively, P < 0.05) and an increased number of apoptotic cells (15.10 ± 9.13 vs. 4.44 ± 2.24, respectively, P < 0.05). In the orthotopic model, the degree of subretinal invasion of tumor cells was significantly reduced after aflibercept treatment (0.07 ± 0.06 vs. 0.15 ± 0.10, P < 0.05). And addition of aflibercept to co-cultures of HUVECs and Y-79, WERI-Rb-1 cells significantly reduced HUVEC proliferation. CONCLUSIONS: Aflibercept reduced retinoblastoma angiogenesis in association with a significant reduction in tumor growth and invasion. These findings suggest that aflibercept could be used in an adjuvant role together with systemic chemotherapy to reduce tumor size and angiogenesis in retinoblastoma.

Advanced Unilateral Retinoblastoma: The Impact of Ophthalmic Artery Chemosurgery on Enucleation Rate and Patient Survival at MSKCC.

PURPOSE: To report on the influence of ophthalmic artery chemosurgery (OAC) on enucleation rates, ocular and patient survival from metastasis and impact on practice patterns at Memorial Sloan Kettering for children with advanced intraocular unilateral retinoblastoma. PATIENTS AND METHODS: Single-center retrospective review of all unilateral retinoblastoma patients with advanced intraocular retinoblastoma treated at MSKCC between our introduction of OAC (May 2006) and December 2014. End points were ocular survival, patient survival from metastases and enucleation rates. RESULTS: 156 eyes of 156 retinoblastoma patients were included. Primary enucleation rates have progressively decreased from a rate of >95% before OAC to 66.7% in the first year of OAC use to the present rate of 7.4%. The percent of patients receiving OAC has progressively increased from 33.3% in 2006 to 92.6% in 2014. Overall, ocular survival was significantly better in eyes treated with OAC in the years 2010-2014 compared to 2006-2009 (p = 0.023, 92.7% vs 68.0% ocular survival at 48 months). There have been no metastatic deaths in the OAC group but two patients treated with primary enucleation have died of metastatic disease. CONCLUSION: OAC was introduced in 2006 and its impact on patient management is profound. Enucleation rates have decreased from over 95% to less than 10%. Our ocular survival rate has also significantly and progressively improved since May 2006. Despite treating more advanced eyes rather then enucleating them patient survival has not been compromised (there have been no metastatic deaths in the OAC group). In our institution, enucleation is no longer the most common treatment for advanced unilateral retinoblastoma.

Blood flow velocity in monocular retinoblastoma assessed by color doppler

OBJECTIVE: To analyze the flow of retrobulbar vessels in retinoblastoma by color Doppler imaging. METHODS: A prospective study of monocular retinoblastoma treated by enucleation between 2010 and 2014. The examination comprised fundoscopy, magnetic resonance imaging, ultrasonography and color Doppler imaging. The peak blood velocities in the central retinal artery and central retinal vein of tumor-containing eyes (tuCRAv and tuCRVv, respectively) were assessed. The velocities were compared with those for normal eyes (nlCRAv and nlCRVv) and correlated with clinical and pathological findings. Tumor dimensions in the pathological sections were compared with those in magnetic resonance imaging and ultrasonography and were correlated with tuCRAv and tuCRVv. In tumor-containing eyes, the resistivity index in the central retinal artery and the pulse index in the central retinal vein were studied in relation to all variables. RESULTS: Eighteen patients were included. Comparisons between tuCRAv and nlCRAv and between tuCRVv and nlCRVv revealed higher velocities in tumor-containing eyes (p <0.001 for both), with a greater effect in the central retinal artery than in the central retinal vein (p =0.024). Magnetic resonance imaging and ultrasonography measurements were as reliable as pathology assessments (p =0.675 and p =0.375, respectively). A positive relationship was found between tuCRAv and the tumor volume (p =0.027). The pulse index in the central retinal vein was lower in male patients (p =0.017) and in eyes with optic nerve invasion (p =0.0088). CONCLUSIONS: TuCRAv and tuCRVv are higher in tumor-containing eyes than in normal eyes. Magnetic resonance imaging and ultrasonography measurements are reliable. The tumor volume is correlated with a higher tuCRAv and a reduced pulse in the central retinal vein is correlated with male sex and optic nerve invasion.

Blood flow velocity in monocular retinoblastoma assessed by color Doppler.

OBJECTIVE: To analyze the flow of retrobulbar vessels in retinoblastoma by color Doppler imaging. METHODS: A prospective study of monocular retinoblastoma treated by enucleation between 2010 and 2014. The examination comprised fundoscopy, magnetic resonance imaging, ultrasonography and color Doppler imaging. The peak blood velocities in the central retinal artery and central retinal vein of tumor-containing eyes (tuCRAv and tuCRVv, respectively) were assessed. The velocities were compared with those for normal eyes (nlCRAv and nlCRVv) and correlated with clinical and pathological findings. Tumor dimensions in the pathological sections were compared with those in magnetic resonance imaging and ultrasonography and were correlated with tuCRAv and tuCRVv. In tumor-containing eyes, the resistivity index in the central retinal artery and the pulse index in the central retinal vein were studied in relation to all variables. RESULTS: Eighteen patients were included. Comparisons between tuCRAv and nlCRAv and between tuCRVv and nlCRVv revealed higher velocities in tumor-containing eyes (p < 0.001 for both), with a greater effect in the central retinal artery than in the central retinal vein (p = 0.024). Magnetic resonance imaging and ultrasonography measurements were as reliable as pathology assessments (p = 0.675 and p = 0.375, respectively). A positive relationship was found between tuCRAv and the tumor volume (p = 0.027). The pulse index in the central retinal vein was lower in male patients (p = 0.017) and in eyes with optic nerve invasion (p = 0.0088). CONCLUSIONS: TuCRAv and tuCRVv are higher in tumor-containing eyes than in normal eyes. Magnetic resonance imaging and ultrasonography measurements are reliable. The tumor volume is correlated with a higher tuCRAv and a reduced pulse in the central retinal vein is correlated with male sex and optic nerve invasion.

Intra-arterial chemotherapy for group C retinoblastoma with adjacent high-flow infantile hemangioma.

Intra-arterial chemotherapy for retinoblastoma is an emerging technique that is being adopted at various centers worldwide. The authors report the first case of an infantile hemangioma that shunted flow during intra-arterial chemotherapy in a 4-month-old girl who presented with macular group C retinoblastoma. Excellent tumor response was noted despite only a fraction of the dose entering the central retinal artery. Further studies to examine intra-arterial chemotherapy's pharmacokinetics and dose-response relations are warranted in order to minimize the necessary exposure to chemotherapy.

Tissue factor regulates tumor angiogenesis of retinoblastoma via the extracellular signal-regulated kinase pathway.

Retinoblastoma, a well-vascularized tumor that is dependent on a very robust angiogenic response, is the most common intraocular malignancy in children. Tissue factor (TF) is known to regulate tumor progression and in the present study we demonstrated that TF regulates tumor angiogenesis of retinoblastoma. In an orthotopic transplantation model of retinoblastoma, TF was selectively expressed in the proliferative area of retinoblastoma including tumor vessels as well as tumor cells, where TF expression was co-localized with endothelial cells of tumor vessels. TF expression progressively increased with fibroblast growth factor-2 (FGF-2)-induced proliferation of human umbilical vein endothelial cells (HUVECs), which was effectively inhibited by blockade of the TF pathway by TF pathway inhibitor (TFPI). In addition, FGF-2-induced angiogenic processes of migration and tube formation of vascular endothelial cells were also effectively suppressed by TFPI, which would be mediated by inhibition of extracellular signal-regulated kinase activation. Therefore, further to our previous report that TF is involved in tumor cell proliferation of retinoblastoma, our current data suggest that blockade of the TF pathway by TFPI could effectively inhibit tumor growth by suppressing tumor cell proliferation and tumor angiogenesis at the same time.

Retinoblastoma treatment: utilization of the glycolytic inhibitor, 2-deoxy-2-fluoro-D-glucose (2-FG), to target the chemoresistant hypoxic regions in LH(BETA)T(AG) retinal tumors.

PURPOSE: To analyze the effect of the glycolytic inhibitor 2-deoxy-2-fluoro-d-glucose (2-FG) on tumor burden, hypoxia, and blood vessels in LH(BETA)T(AG) retinal tumors. METHODS: Seventeen-week-old LH(BETA)T(AG) retinal tumor eyes (n = 36) were treated with 2-FG and analyzed at 1 day and 1 week post a single treatment, and 1 day post a biweekly treatment for 3 weeks. Tumor sections were analyzed for hypoxia, tumor burden, and vasculature. To assess tumor burden, sections were processed for standard hematoxylin-eosin (H&E) staining. Immunofluorescent techniques were used to stain for new and mature blood vessels. RESULTS: Hypoxia and tumor burden reduction are significantly different between the treatment schedules used (P < 0.001). Eyes treated with 2-FG for 3 weeks showed a significant decrease in hypoxia (P = 0.001) and tumor burden (P = 0.009); whereas those treated with one injection and evaluated at 1 day and 1 week postinjection did not show a decrease in either hypoxia (P = 0.373 and P = 0.782, respectively) or tumor burden (P = 0.203 and P = 0.836, respectively). When evaluating the spatial distribution of hypoxic regions in the different areas of the tumor, 2-FG showed a differential effect on hypoxia depending on the area. Hypoxia was most decreased in the base of the treated eyes with a 95% reduction (P < 0.001). CONCLUSIONS: This is the first study to elucidate that 2-FG treatment in retinoblastoma produces an impact on hypoxia and a concomitant decrease on tumor burden. In this study, the authors validate their previous studies by revealing that glycolytic inhibitors effectively target hypoxia in retinoblastoma tumors. The future application of 2-FG as an adjuvant treatment to standard chemotherapy may enhance the treatment of retinoblastoma.

[HIF-1alpha, HPSE and VEGF promote malignant progression of retinoblastoma].

OBJECTIVE: To investigate the expression of heparanase (HPSE), hypoxia-inducible factor (HIF-1alpha) and their correlation with expression of vascular endothelial growth factor (VEGF) and microvessel density (MVD) in retinoblastoma. METHODS: HIF-1alpha and VEGF were detected by SP immunohistochemical method in 34 cases of retinoblastoma and 10 cases of normal retina tissues. MVD was measured by anti-CD34. Eighteen samples of retinoblastoma tissues and ten samples of normal retina were examined for HPSE mRNA, HIF-1alpha mRNA, VEGF mRNA expression by RT-PCR. The correlation between HPSE, HIF-1alpha and VEGF expression, MVD and clinical and pathological characters were analyzed. The statistical methods are the measurement data using grouped quantitative data t test, variance analysis and q test; enumeration data compared with chi(2) test, Fisher test and rank sum test; correlation analysis using Spearman rank correlation analysis and the kappa test. RESULTS: The positive expression rates of HIF-1alpha and VEGF were 58.8%, 64.7% higher in retinoblastoma than in normal retina's (chi(2) = 10.784, P < 0.05; chi(2) = 9.269, P < 0.05). Positive expression of HPSE, HIF-1alpha, VEGF mRNA were found in 55.6%, 44.4%, 72.2%. The expression of HIF-lalpha and VEGF in retinoblastoma were correlated with MVD (r = 0.664, P < 0.05; r = 0.590, P < 0.05). VEGF was correlated with HPSE and HIF-1alpha (Z = 2.350, P = 0.009; Z = 2.940, P = 0.002). CONCLUSIONS: HPSE and HIF-1alpha can influence the expression of VEGF, an important angiogenesis factor. HPSE, HIF-1alpha and VEGF play a role in tumor angiogenesis and promote malignant progress of retinoblastoma.

Expression of vascular endothelial growth factor in retinoblastoma.

OBJECTIVES: To investigate the immunohistochemical expression of vascular endothelial growth factor (VEGF) and to determine its possible association with tumor differentiation status, optic nerve and/or choroidal invasion, anterior chamber invasion, vitreous seeding, and basophilic staining of the vascular walls. METHODS: A retrospective study was performed to identify the expression of VEGF in 47 of 129 consecutive patients with retinoblastoma treated at the Ocular Pathology Laboratory of the Anatomy and Pathology Institute of the Central University of Venezuela in Caracas from January 1, 2000, through December 31, 2007. RESULTS: A positive correlation between VEGF staining intensity and time of progression and mitotic and apoptotic indexes was observed. However, no correlation was found between VEGF expression and other prognostic factors in this malignant neoplasm, including tumor stage as assessed by the Grabowski and Abramson classification. CONCLUSIONS: Although the isolated characterization of VEGF in retinoblastoma is not grounds for this protein to be considered a prognostic factor, its association with mitotic and apoptotic indexes suggests it may play a role in the progression of this disease. Thus, therapeutic targeting of VEGF in retinoblastoma may be an effective strategy to reduce tumor progression.

Impact of tumor-associated macrophages in LH(BETA)T(AG) mice on retinal tumor progression: relation to macrophage subtype.

PURPOSE: To determine the distribution of tumor-associated macrophages (TAMs) during retinoblastoma tumor development, examine the contribution of bone marrow-derived TAMs in retinoblastoma tumors, and evaluate the supportive role of TAMs in tumor growth in a transgenic retinoblastoma mouse model. METHODS: The time course of macrophage infiltration in transgenic retinoblastoma tumors was assessed by immunohistochemistry at different time points in tumorigenesis. The origin of TAMs in transgenic retinoblastoma tumors was determined by transplanting 10(7) bone marrow cells from green fluorescent protein (GFP)-positive 16-week-old mice into age-matched, irradiated LH(BETA)T(AG) mice via tail vein injections. Macrophage depletion was performed by subconjunctival (SC) delivery of liposomal clodronate. RESULTS: The density of TAMs increased from 4 to 12 weeks of age in mice with small to medium tumors (P = 0.037) and remained stable in the later stages of disease (i.e., 16 weeks old with large tumors; P = 0.20). In 16-week-old mice, 38% (2.5 +/- 3.2 cells per 400x high-power field) of TAMs were GFP-positive, bone marrow-derived macrophages. Total TAM depletion was associated with a significant decrease in the expression levels of MMP-9 (P = 0.014) and mature vessels (P < 0.001) and a nonsignificant decrease in the density of neovessels (P = 0.94). The density of M2-polarized TAMs did not change significantly after TAM depletion (P = 0.68). After M1-polarized TAM depletion, the tumor burden increased (P = 0.056). CONCLUSIONS: This work extends understanding of the complex role that macrophages play in retinoblastoma. Macrophage modulation in the tumor microenvironment is a critical factor in retinoblastoma tumor progression.

Contrast-enhancement of the anterior eye segment in patients with retinoblastoma: correlation between clinical, MR imaging, and histopathologic findings.

BACKGROUND AND PURPOSE: AES contrast-enhancement is recognized in a substantial number of retinoblastoma-affected eyes. We retrospectively investigated the histopathologic basis of AES contrast-enhancement on MR images in retinoblastoma. MATERIALS AND METHODS: Pretreatment contrast-enhanced MR images were obtained from 42 children with retinoblastoma. Forty-two enucleated eyes were included in this study, AES enhancement was evaluated by using a 3-point score, and these data were correlated with clinical, MR imaging, and histopathologic findings. Additionally, 14 specimens were immunohistochemically analyzed for CD31, VEGF, and Flt-1 expression. Statistical correlations with AES enhancement were assessed by using a linear-by-linear association test and univariate and multivariate ordinal regressions. RESULTS: The degree of abnormal AES enhancement was moderate in 15 (36%) eyes and strong in 14 (33%) eyes, whereas 13 (31%) eyes showed normal AES enhancement. In multivariate analysis, the degree of AES enhancement showed statistically significant correlations with iris surface-vessel count (P = .05) and optic nerve invasion (P = .04) in the enucleated eye and with tumor volume (P = .02) as detected on MR imaging. No significant associations between AES enhancement and VEGF expression in the iris were observed. Flt-1 (P = .04) staining in iris stroma and IA as detected with CD31 staining (P = .009) both yielded a statistically significant positive correlation with abnormal AES enhancement. CONCLUSIONS: The degree of abnormal AES enhancement on MR imaging in retinoblastoma reflects angiogenesis in the iris. AES enhancement is also a hallmark of advanced retinoblastoma because its degree correlates with tumor volume and optic nerve invasion.

[Relationship between vasculogenic mimicry and clinical pathological characters in retinoblastoma].

OBJECTIVE: To explore if vasculogenic mimicry (VM) exists in retinoblastoma (Rb) and to explore the clinical significance of VM. METHODS: It was an experimental study. Sixty Rb specimens with complete clinical and prognostic data were collected. Periodic acid-Schif staining and immunohistochemical staining of CD34 were conducted to explore if VM exists in those Rb specimens. The expression of HIF-1alpha and VEGF were examined by immunohistochemical staining. The expression of CD34 endothelial antigen was used to label the neo-microvessels. Microvessel density (MVD) in retinoblastoma tissues was calculated. RESULTS: In HE staining slides, VM was present in Rb specimens and was formed by tumor cells but not endothelial cells. Red blood cells were present in the VM. VM existed in 18.33% (11/60) of the Rb specimens. Low R-E graded Rb specimens exhibited a higher VM positive rate than that in the high R-E graded Rb (chi(2) = 8.861, P < 0.05). The positive rate of VM was 4.34% in differentiated type of Rb and was 22.02% in undifferentiated type of Rb (chi(2) = 4.872, P < 0.05). HIF-1alpha and VEGF expressions in Rb with VM were significantly greater than those in Rb without VM (P = 0.001). The density of endothelial vessels correlated with VM. The mean MVD was 49.77 +/- 2.05 in Rb without VM and 36.53 +/- 1.15 in Rb with VM (P < 0.05). CONCLUSIONS: VM exists in Rb. Highly differentiated Rb exhibits more VM than that in less differentiated Rb. Expression of HIF-1alpha and VEGF is greater in Rb with VM, indicating that these factors may stimulate the occurrence of VM.

Increased hypoxia following vessel targeting in a murine model of retinoblastoma.

PURPOSE: The purpose of this study was to evaluate the effects of vessel targeting and chemotherapy agents on inducing hypoxic regions in LH(BETA)T(AG) murine retinal tumors. METHODS. Twelve- and 16-week-old LH(BETA)T(AG) transgenic retinoblastoma mice were treated with periocular injections to the right eye only of saline (n = 42), anecortave acetate (a single injection; 300 microg/20 microL; n = 42), or carboplatin (two injections per week for 3 weeks; 62.5 microg/20 microL; n = 42). Eyes were enucleated 1 day, 1 week, and 1 month after injection. To assess hypoxia, mice received 60 mg/kg pimonidazole via intraperitoneal injection. Eyes were enucleated, and tumor sections were analyzed. RESULTS: Levels of hypoxia significantly increase in 16-week-old animals 1 day and 1 week after treatment with anecortave acetate, a known angiostatic agent. Eyes treated with anecortave acetate showed a 28% (P < 0.001) increase in hypoxic regions in comparison with the saline-treated control group 1 day after injection and a 17% (P < 0.001) increase 1 week after injection. In early tumors of 12-week-old animals, levels of hypoxia increased by 2.0% (P = 0.011) 1 day after anecortave acetate injection compared to controls. Levels of hypoxia significantly decrease in 16-week-old animals 1 week and 1 month after treatment with carboplatin, a chemotherapeutic agent. Eyes treated with carboplatin showed a 21.7% (P = 0.017) decrease in hypoxic regions in comparison with the saline-treated control group 1 week after injection and a 4.51% (P < 0.001) decrease 1 month after injection. In early tumors of 12-week-old animals, levels of hypoxia decreased by 0.0429% (P < 0.001) 1 month after carboplatin injection compared with controls. CONCLUSIONS: Treatment with a vessel-targeting agent results in changes in the tumor microenvironment as early as 1 day after treatment. By increasing hypoxia in tumors, vessel-targeting agents can be combined with glycolytic inhibitors which have been shown previously to target hypoxic regions in this transgenic model. This approach may have benefits for children with this disease and should be further investigated.

Blood vessel maturation in retinoblastoma tumors: spatial distribution of neovessels and mature vessels and its impact on ocular treatment.

PURPOSE: The purposes of this study were to evaluate the spatial distribution of neovessels versus mature vessels in both human retinoblastoma (RB) and LH(BETA)T(AG) tumors, assess similarities and differences between the animal model and the human RB specimens, and determine whether vessel maturation is associated with risk factors for metastasis. METHODS: Immunohistochemical analyses were performed on human (n = 10) and LH(BETA)T(AG) (n = 11) enucleation specimens to evaluate the spatial distribution of neovessels and mature vessels. In human RB, vessel maturation was correlated with treatment history and metastatic risk factors. RESULTS: In human RB, the percentage of neovessels was higher in the periphery of the tumor than in the center (P = 0.021). This finding was mostly attributed to the distribution of large-caliber vessels (i.e., neovessels were higher in the periphery for large [P = 0.050]- and medium [P = 0.032]-caliber vessels; and mature vessels were higher in the center for large-caliber vessels [P = 0.032]). In this small series, vessel maturation did not correlate with risk for metastasis. Similar results were observed in LH(BETA)T(AG) tumors. The percentage of large-caliber neovessels was higher in the periphery than in the center (P = 0.038). CONCLUSIONS: There is a spatially distributed, heterogeneous vessel population containing neovessels and mature vessels in advanced RB disease. There is a significantly higher concentration of mature, large-caliber vessels in the center of tumors that is similar in human RB and LH(BETA)T(AG) retinal tumors. From these data the authors hypothesize that tumor vessel maturation in RB initiates in central regions of the tumor and radiates toward the periphery.