# MOLECULAR BASIS OF SENESCENCE IN BREAST EPITHELIAL CELLS

> **NIH NIH R01** · DANA-FARBER CANCER INST · 1992 · $219,295

## Abstract

The fundamental goal of this project is to define a primary, molecular
mechanism of breast cancer, a major disease affecting one in nine women in
the U.S. over their lifespan.  The model system employed to achieve this
objective is an extensive series of human papilloma virus (HPV) DNA-
immortalized human mammary epithelial cell lines that have been well
characterized for karyotype, for growth factor requirements, and for the
single viral oncoprotein, HPV E6, required for their immortalization.  The
HPV-immortalized and paired normal, senescing cells, from which they are
derived, offer a unique opportunity to identify genes responsible for
maintenance of the senescence phenotype in mammary epithelial cells.

The finding of a consensus loss of chromosome 19 in the HPV cells has led
to the hypothesis that this chromosome contains a gene or genes, which when
lost or inactivated, allows mammary epithelial cells to escape senescence
or terminal differentiation.  Key experiments, using microcell hybrids to
reconstitute chromosome 19, will test the hypothesis directly.  Parallel
introduction of other human chromosomes (e.g. 4 and 15) into HPV cells
serve as controls for microcell hybridization efficiency and as controls
for chromosome specificity in reconstituting the senescent phenotype.

To clone the specific gene(s) responsible for escape from senescence,
differential screening of a chromosome 19 genomic library as well as
subtractive hybridization are proposed.  For differential screening, CDNA
from normal and HPV cells will be used to screen duplicate filters from a
chromosome 19 lamda library.  Subtraction between normal CDNA and HPV MRNA
will elucidate genes expressed exclusively in the senescing cells.

Only the E6 oncoprotein is required for HPV16 immortalization of mammary
epithelial cells.  As the E6 protein is involved in the reduction of the
p53 gene product, a potential tumor suppressor in breast cancer, our
mammary cell system will be utilized to study the respective and
interactive roles of p53 and E6 in the senescent phenotype.  To test
whether the continued function of E6 is required for the immortal
phenotype, knockout strategies, using antisense oligonucleotides as well as
antisense RNA will be employed.

Our planned studies offer insights into the disease of breast cancer by the
identification of genes necessary to preserve the delicately balanced
states of senescence and cellular transformation.

## Key facts

- **NIH application ID:** 3122778
- **Project number:** 1R01AG010819-01
- **Recipient organization:** DANA-FARBER CANCER INST
- **SAM.gov UEI:** DPMGH9MG1X67
- **Principal Investigator:** RUTH SAGER
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1992
- **Award amount:** $219,295
- **Award type:** 1
- **Project period:** 1992-08-01 → 1995-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3122778

## Citation

> US National Institutes of Health, RePORTER application 3122778, MOLECULAR BASIS OF SENESCENCE IN BREAST EPITHELIAL CELLS (1R01AG010819-01). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3122778. Licensed CC0.

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