GENE INTERACTIONS IN COLON CANCER

Project: Research project

Project Details

Description

The c-myc gene is overexpressed in human colon tumors and rigorous
quantitative and statistical analysis has demonstrated that the gene is
frequently amplified from 2 to 5 fold in these tumors. Moreover, in a
phase III study of 5FU based adjuvant therapy for colon cancer,
amplification of the c-myc gene identified the subset of patients who
show improved disease free and overall survival in response to
treatment. c-myc may influence outcome in at least 3 ways: both c-myc
and thymidylate synthase (TS) bind TS protein and are translationally
regulated by formation of these ribonucleoprotein structures,
establishing a potentially complex interaction between c-myc and TS mRNA
levels in regulating TS activity; stimulation of proliferation may
stimulate TS expression, a gene regulated in the cell cycle; and c-myc
may influence proliferation, differentiation and apoptosis of colonic
epithelial cells independent of affects on TS.

The goal of this application is two fold: 1st, to understand how c-myc
amplification and expression modulate TS mRNA, protein, RNP complex
formation, and final TS activity and sensitivity to 5FU. This will be
done by investigating these interactions in a panel of colon carcinoma
cell lines which we have characterized as to level of c-myc
amplification. We will then utilize expression vectors containing wild-
type c-myc, the c-myc: TS binding site, c-myc with deleted or mutated
TS binding site, or a chimeric c-myc:estrogen receptor construct to
dissect the influence of expression of c-myc mRNA, protein, and/or c-myc
activity on TS mRNA, protein and activity and sensitivity to 5FU.
Preliminary data already indicate that c-myc and TS mRNA levels appear
to be tightly linked. 2nd, we will utilize novel automated cytometry,
fluorescent probe methodology and imaging technology, recently reported
in Science by our coinivestigator, which is capable of analysis of DNA
and RNA levels in situ with single molecule sensitivity and resolution,
to address the heterogeneity of c-myc and TS gene copy number and mRNA
content. Following initial analysis of cell lines for calibration and
base line measurements, the DiscoveryTM system will be applied to tumor
and normal tissue sections (already in our possession) from over 700
patients entered into two phase III studies of adjuvant therapy for
colon cancer conducted by ECOG. A continuation of our successful
collaboration with ECOG biostatistics will test whether the interaction
of c-myc and TS, and the cellular distribution of amplification and/or
expression of these genes, is prognostic for either outcome or response
to adjuvant therapy.
StatusFinished
Effective start/end date4/6/991/31/05

Funding

  • National Cancer Institute: $305,059.00
  • National Cancer Institute: $297,323.00
  • National Cancer Institute
  • National Cancer Institute: $312,117.00
  • National Cancer Institute: $290,378.00

ASJC

  • Cancer Research
  • Oncology

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