National Cancer Institute®
Last Modified: April 1, 2002
UI - 11905807
AU - Knudson A G
TI - Two genetic hits (more or less) to cancer.
SO - Nature Rev Cancer 2001 Nov;1(2):157-62
AD - Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111, USA. email@example.com
Most cancers have many chromosomal abnormalities, both in number and in structure, whereas some show only a single aberration. In the era before molecular biology, cancer researchers, studying both human and animal cancers, proposed that a small number of events was needed for carcinogenesis. Evidence from the recent molecular era also indicates that cancers can arise from small numbers of events that affect common cell birth and death processes.
UI - 1848638
AU - Tuck AB; Wilson SM; Khokha R; Chambers AF
TI - Different patterns of gene expression in ras-resistant and ras-sensitive cells.
SO - J Natl Cancer Inst 1991 Apr 3;83(7):485-91
AD - London Regional Cancer Centre, Ontario, Canada.
We have shown previously that nontumorigenic NIH 3T3 cells can be made tumorigenic and metastatic by transfection and expression of activated ras, whereas in LTA cells, which are tumorigenic but nonmetastatic, the degree of malignancy is not altered by ras. To investigate possible mechanisms of natural ras resistance, we compared the expression patterns of several genes thought to be involved in ras-induced metastatic progression in LTA (ras-resistant) and NIH 3T3 (ras-sensitive) cells, before and after constitutive expression of transfected T24-H-ras. We examined the expression of the nuclear "early-response" genes jun and fos and the "tumor-suppressor" retinoblastoma (Rb) gene, as well as genes involved in invasion (major excreted protein [MEP], tissue inhibitor of metalloproteinases [TIMP]), and cell adhesion (secreted phosphoprotein 1 [SPP1; also known as osteopontin]). We found distinct differences in both the basal and ras-induced levels of expression of most of these genes in LTA versus NIH 3T3 cells. High levels of MEP and low levels of TIMP were induced in ras-transfected NIH 3T3 cells, whereas LTA cells showed intermediate levels of MEP and high levels of TIMP that were only marginally affected by the expression of transfected ras. Similarly, SPP1 expression was strongly induced by ras in NIH 3T3 cells but was repressed by ras in LTA cells. Enzymogram assays for functional gelatinase activity showed an increase in 67-kd and 62-kd bands in NIH 3T3 cells in the presence of ras. LTA cells showed no gelatinolytic activity in the presence or absence of ras. Data from an in vitro assay for chemoinvasiveness showed a pattern as predicted from the expression of invasion-related genes; chemoinvasiveness in ras-transfected NIH 3T3 was greater than in LTA and ras-transfected LTA cells, which was greater than in NIH 3T3 cells. Differences in expression of the genes examined are believed to contribute to the ras responsiveness of NIH 3T3 cells and the ras resistance of LTA cells.
UI - 11911245
AU - Kondo Y; Tanaka Y; Shields J A; Kondo S
TI - Association between telomerase activity and basic fibroblast growth factor up-regulation in retinoblastomas.
SO - Anticancer Res 2001 Nov-Dec;21(6A):3765-72
AD - Center for Surgery Research, The Cleveland Clinic Foundation, OH 44195, USA. Yasuko.Kondo@mssm.edu
BACKGROUND: Telomerase is an enzyme associated with cellular immortality and malignancy in many cell types. On the other hand, growth factors such as basic fibroblast growth factor (bFGF) or platelet-derived growth factor (PDGF) promote tumor growth, whereas the association between telomerase and these growth factors remains unclear. MATERIALS AND METHODS: Telomerase activity and expression of bFGF and PDGF were assayed in 9 retinoblastoma tissues and 2 cell lines (WERI-Rb-1 and Y79). The association of telomerase activity with bFGF or PDGF was investigated. RESULTS: Telomerase activity was detected in three out of nine tissues and both cell lines. Two telomerase highly-positive tissues and WERI-Rb-1 and Y79 cells expressed bFGF. As for the expression of PDGF, only one retinoblastoma tissue with high telomerase was positive. To further determine whether telomerase activity and bFGF are closely associated, we inhibited each expression. Inhibition of telomerase in WERI-Rb-1 cells using the anti-sense treatment suppressed the expression of bFGF and subsequently induced apoptosis after 25 to 30 doublings. When bFGF expression was suppressed by the neutralizing antibody, telomerase activity was not affected nor was apoptosis detected. CONCLUSION: Telomerase may up-regulate the expression of bFGF and protect retinoblastoma cells from cell death, indicating, the possibility that inhibition of telomerase is a promising approach for the treatment of telomerase-positive tumors.
UI - 11920795
AU - Pandya J; Valverde K; Heon E; Blaser S; Gallie BL; Chan HS
TI - Predilection of retinoblastoma metastases for the mandible.
SO - Med Pediatr Oncol 2002 Apr;38(4):271-3
AD - Division of Hematology and Oncology, Department of Pediatrics, Hospital for Sick Children, University of Toronto, 555 University Avenue, Toronto, Ontario, Canada M5G 1X8.
UI - 11920804
AU - Hadjistilianou T; Mastrangelo D; Mazzotta C; De Francesco S; Capretti C;
TI - Lore C 13q deletion syndrome associated with retinoblastoma and clinical anophthalmos of the opposite eye.
SO - Med Pediatr Oncol 2002 Apr;38(4):293-4
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