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Cancer Lett. 2014 Nov 28;354(2):336-47. doi: 10.1016/j.canlet.2014.08.043. Epub 2014 Sep 1.

Loss-of-function RNAi screens in breast cancer cells identify AURKB, PLK1, PIK3R1, MAPK12, PRKD2, and PTK6 as sensitizing targets of rapamycin activity.

Author information

1
Genetics Branch, National Institutes of Health, Bethesda, MD 20892, USA.
2
Laboratory of Cancer Biology and Genetics, National Institutes of Health, Bethesda, MD 20892, USA.
3
Office of Science and Technology Partnerships, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
4
Division of Preclinical Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD 20850, USA.
5
Genetics Branch, National Institutes of Health, Bethesda, MD 20892, USA. Electronic address: ncaplen@mail.nih.gov.

Abstract

The use of molecularly targeted drugs as single agents has shown limited utility in many tumor types, largely due to the complex and redundant nature of oncogenic signaling networks. Targeting of the PI3K/AKT/mTOR pathway through inhibition of mTOR in combination with aromatase inhibitors has seen success in particular sub-types of breast cancer and there is a need to identify additional synergistic combinations to maximize the clinical potential of mTOR inhibitors. We have used loss-of-function RNAi screens of the mTOR inhibitor rapamycin to identify sensitizers of mTOR inhibition. RNAi screens conducted in combination with rapamycin in multiple breast cancer cell lines identified six genes, AURKB, PLK1, PIK3R1, MAPK12, PRKD2, and PTK6 that when silenced, each enhanced the sensitivity of multiple breast cancer lines to rapamycin. Using selective pharmacological agents we confirmed that inhibition of AURKB or PLK1 synergizes with rapamycin. Compound-associated gene expression data suggested histone deacetylation (HDAC) inhibition as a strategy for reducing the expression of several of the rapamycin-sensitizing genes, and we tested and validated this using the HDAC inhibitor entinostat in vitro and in vivo. Our findings indicate new approaches for enhancing the efficacy of rapamycin including the use of combining its application with HDAC inhibition.

KEYWORDS:

Breast cancer; HDAC inhibition; RNAi screen; Rapamycin

PMID:
25193464
PMCID:
PMC4240001
DOI:
10.1016/j.canlet.2014.08.043
[Indexed for MEDLINE]
Free PMC Article

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