RESUMO
PURPOSE: This study investigated the relationship between B lymphoma Mo-MLV insertion region 1 (BMI-1)--a polycomb protein for stem cell self-renewal and proliferation--and the clinicopathological parameters of human retinoblastomas, including differentiation status and retinal tissue invasion, as well as the effects of BMI-1 on retinoblastoma Y79 cells. METHODS: Thirty-four archived human retinoblastoma samples were recruited for BMI-1 immunohistochemistry. The percentage of BMI-1-expressing cells was scored by independent pathologists and the data were correlated with the clinical features. Y79 cells were transfected to overexpress or specifically inhibit BMI-1 for cell proliferation, propidium iodide cell cycle and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) apoptosis analyses, multicellular sphere formation assay, and gene expression study. RESULTS: BMI-1 was widely expressed in human retinoblastomas. Higher percentages of BMI-1-expressing cells were selectively limited to undifferentiated tumors and those tumors undergoing invasion to the optic nerve and choroid. However, there was no difference in BMI-1 expression in retinoblastoma retinas with or without tumor invasion. In Y79 cells, BMI-1 stimulated cell proliferation and suppressed apoptosis with reduced p14ARF and p16INK4 expression, along with upregulation of proliferating cell nuclear antigens cyclin D1 and D2. In contrast, silencing BMI-1 reversed these changes. It also upregulated CHX10 and Rx, but not other retinal development-related genes, including nestin and neurofilament M. CONCLUSIONS: Our work indicates that BMI-1 might render important oncogenic property of retinoblastomas and it could be a therapeutic target for the cancer treatment.
Assuntos
Transformação Celular Neoplásica/patologia , Complexo Repressor Polycomb 1/metabolismo , Retinoblastoma/metabolismo , Retinoblastoma/patologia , Apoptose/genética , Diferenciação Celular , Linhagem Celular Tumoral , Proliferação de Células , Transformação Celular Neoplásica/genética , Pré-Escolar , Demografia , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Masculino , Invasividade Neoplásica , Complexo Repressor Polycomb 1/genética , Retinoblastoma/genética , Esferoides Celulares/metabolismo , Esferoides Celulares/patologia , Coloração e RotulagemRESUMO
OBJECTIVE: To investigate the ocular hypertensive response to topical dexamethasone (DEX), rimexolone (RIM), loteprednol etabonate (LOT) and fluorometholone (FML) in rabbits of different ages. METHODS: Seventy-five rabbits of three age groups (7 weeks, 6 months and 1-year old) received topical administration of 0.1% DEX, 1% RIM, 0.5% LOT, 0.1% FML or balanced salt solution four times daily for 1 month. Intraocular pressure (IOP) was monitored at regular time intervals. After a month, eyes were harvested for histological study with haematoxylin and eosin (H&E), periodic acid Schiff and Masson trichrome staining. Trabecular meshwork changes were graded by masked ocular pathologists. RESULTS: Topical DEX caused the greatest increase in IOP, followed by RIM and FML. LOT caused the least IOP increase. Similar pattern of IOP response to the four corticosteroids was observed in the three studied age groups. Young rabbits (7 week) were the most responsive to corticosteroids among the age groups. Extracellular matrix thickening in the trabecular meshwork region and loss of trabecular meshwork cells were observed after DEX, FML or RIM treatments. CONCLUSION: Young rabbits are more susceptible to steroid induced increase in IOP, even for milder steroids such as fluorometholone and rimexolone.
