National Cancer Institute®
Last Modified: April 1, 2002
1
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.
ag_knudson@fccc.edu
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.
2
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.
3
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.
4
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.
5
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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