Related Experiment Video
Updated: Aug 30, 2026

Silencing of BRCA2 to Identify Novel BRCA2-regulated Biological Functions in Cultured Human Cells
Published on: August 12, 2015
BRCA1 inhibition of telomerase activity in cultured cells
Jingbo Xiong1, Saijun Fan, Qinghui Meng
1Department of Radiation Oncology, Long Island Jewish Medical Center, The Long Island Campus for the Albert Einstein College of Medicine, New Hyde Park, New York 11040, USA.
Abstract:
Telomerase, an enzyme that maintains telomere length, plays major roles in cellular immortalization and cancer progression. We found that an exogenous BRCA1 gene strongly inhibited telomerase enzymatic activity in human prostate and breast cancer cell lines and caused telomere shortening in cell lines expressing wild-type BRCA1 (wtBRCA1) but not a tumor-associated mutant BRCA1 (T300G). wtBRCA1 inhibited the expression of the catalytic subunit (telomerase reverse transcriptase [TERT]) but had no effect on the expression of a subset of other components of the telomerase holoenzyme or on the expression of c-Myc, a transcriptional activator of TERT. However, endogenous BRCA1 associated and partially colocalized with c-Myc; exogenous wtBRCA1 strongly suppressed TERT promoter activity in various cell lines. The TERT inhibition was due, in part, to suppression of c-Myc E-box-mediated transcriptional activity. Suppression of TERT promoter and c-Myc activity required the amino terminus of BRCA1 but not the carboxyl terminus. Finally, endogenous BRCA1 and c-Myc were detected on transfected mouse and human TERT promoter segments in vivo. We postulate that inhibition of telomerase may contribute to the BRCA1 tumor suppressor activity.
Related Concept Videos
Telomeres and Telomerase
Replicative Cell Senescence
The Retinoblastoma Gene
The first-ever tumor suppressor gene called Rb was identified in retinoblastoma - a rare eye tumor in children. In inherited forms of the disease, a child inherits one defective copy of the Rb gene, which predisposes them to retinoblastoma. However,...
Inhibition of Cdk Activity
Inhibition of CDK Activity
mTOR Signaling and Cancer Progression
The mTOR pathway or the...

