Retinoblastoma tumor cells

All patients with anterior uveitis should undergo dilated funduscopy. Such examination should be attempted on the initial visit, although it may be difficult because of patient discomfort and/or posterior synechia. In such cases, ophthalmoscopy on the first follow-up visit may yield more useful information. Without adequate careful examination of the peripheral fundus and posterior pole, one cannot rule out the possibility of posterior involvement or masquerade syndromes. Masquerade syndromes are disorders that present as uveitis but do not have an inflammatory etiology. Such diseases either cause a secondary uveitis or are mistaken for a primary uveitis, because of the presence of white cells, red blood cells, pigment, or tumor cells. Examples of masquerade syndromes may include lymphoma, leukemia, retinoblastoma, malignant choroidal melanoma, retinal detachment, and intraocular foreign body. 

Goddard AD, Balakier H, Clanton M, et al. Infirequent genomic rearrangement and normal expression of the putative RBI gene in retinoblastoma tumors. Mol Cell Biol 1988 8 2082-91. 

Horowitz, J.M., S.H. Par, E. Bogenmann, J.C. Cheng, D.W. Yandell, F.J. Kaye, T.P. Dryja and R.A. Weinberg. Frequent inactivation of retinoblastoma anti-oncogene is restricted to a subset of human tumor cells. Proc. Natl. Acad. Sci. USA 87 2775-2790, 1990. 

Several lipoprotein formulations have been tested for delivery of photosensitizers to tumor tissue [54-56] and it has been shown that LDL is a particularly suitable delivery vehicle for different porphyrins. Uptake of LDL complex is mainly mediated via an active endocytotic pathway, involving LDL receptors on both tumor cells and endothelial cells [57-60]. Depending on the time after administration, the LDL complexed photosensitizers can be found either in the vasculature [61], or in the tumor cells themselves [57,62]. Covalent linkage of LDL to chlorin e6 resulted in conjugates which were specifically taken up by LDL-receptor carrying fibroblasts, and a retinoblastoma cell line, indicating its potential use in ocular tumors [54]. 

Tat-PTD. The resultant Tat-p53N peptide induced the rapid accumulation of p53 and the activation of apoptotic genes, and it resulted in the preferential killing of tumor cells and the regression of human retinoblastoma cells in rabbit eyes [9]. Minimal retinal damage was observed after intravitreal injection [9]. 

Bradley JS, Olson C, Oberholzer M, Lin Y, Zones JM, Kohll HS, Bisova K, Fang S-C, Meisenheider J, Hunter T, Umen JG. Regulation of the Chlamydomonas cell cycle by a stable, chromatin-associated retinoblastoma tumor suppressor complex. Plant Cell. 2010 22 3331-47. 

Khosravi-Far R, Esposti MD (2004) Death receptor signals to mitochondria. Cancer Biol Ther 3 1051 -1057 Kim R et al (2006) Role of mitochondria as the gardens of cell death. Cancer Chemother Pharmacol 57 545-553 Kipreos ET, Wang JY (1990) Differential phosphorylation of c-Abl in cell cycle determined by cdc2 kinase and phosphatase activity. Science 248 217-220 Knudsen ES, Knudsen KE (2006) Retinoblastoma tumor suppressor where cancer meets the cell cycle. Exp Biol Med (Maywood) 231 1271-1281... 

A second example of inherited predisposition to cancer is provided by hereditary retinoblastoma. This is a rare tumor of the retina and, when it develops, it generally develops in one eye only. Nonetheless, in children with hereditary retinoblastoma, the cancer develops early in life and generally in both eyes. This is a striking example of the inherited predisposition to develop a tumor. As in the case of hereditary polyposis, the defect is in a tumor suppressor gene, in this case RBI. Here too patients have just one intact gene in each of their cells and a single mutation in that gene may be aU that is required to initiate tumor development. 

One of the most important of the tumor suppressor genes is Rb. Mutant Rb genes are found in many human tumors, including retinoblastoma (as cited earlier). The Rb protein is a potent inhibitor of cell division. Loss of Rb function will lead to abnormal cell division and, ultimately, to cell transformation. 

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