Small interfering RNA screens reveal enhanced cisplatin cytotoxicity in tumor cells having both BRCA network and TP53 disruptions.
RNA interference technology allows the systematic genetic analysis of the molecular alterations in cancer cells and how these alterations affect response to therapies. Here we used small interfering RNA (siRNA) screens to identify genes that enhance the cytotoxicity (enhancers) of established anticancer chemotherapeutics. Hits identified in drug enhancer screens of cisplatin, gemcitabine, and paclitaxel were largely unique to the drug being tested and could be linked to the drug's mechanism of action. Hits identified by screening of a genome-scale siRNA library for cisplatin enhancers in TP53-deficient HeLa cells were significantly enriched for genes with annotated functions in DNA damage repair as well as poorly characterized genes likely having novel functions in this process. We followed up on a subset of the hits from the cisplatin enhancer screen and validated a number of enhancers whose products interact with BRCA1 and/or BRCA2. TP53(+/-) matched-pair cell lines were used to determine if knockdown of BRCA1, BRCA2, or validated hits that associate with BRCA1 and BRCA2 selectively enhances cisplatin cytotoxicity in TP53-deficient cells. Silencing of BRCA1, BRCA2, or BRCA1/2-associated genes enhanced cisplatin cytotoxicity approximately 4- to 7-fold more in TP53-deficient cells than in matched TP53 wild-type cells. Thus, tumor cells having disruptions in BRCA1/2 network genes and TP53 together are more sensitive to cisplatin than cells with either disruption alone.
Bartz
Steven R
SR
Rosetta Inpharmatics, LLC, Seattle, WA 98109, USA. steven_bartz@merck.com
Zhang
Zhan
Z
Burchard
Julja
J
Imakura
Maki
M
Martin
Melissa
M
Palmieri
Anthony
A
Needham
Rachel
R
Guo
Jie
J
Gordon
Marcia
M
Chung
Namjin
N
Warrener
Paul
P
Jackson
Aimee L
AL
Carleton
Michael
M
Oatley
Melissa
M
Locco
Louis
L
Santini
Francesca
F
Smith
Todd
T
Kunapuli
Priya
P
Ferrer
Marc
M
Strulovici
Berta
B
Friend
Stephen H
SH
Linsley
Peter S
PS
D000970:Antineoplastic Agents / Q000633:toxicity*; D019313:BRCA1 Protein / Q000037:antagonists & inhibitors* / Q000378:metabolism; D024682:BRCA2 Protein / Q000037:antagonists & inhibitors* / Q000378:metabolism; D045744:Cell Line, Tumor; D002945:Cisplatin / Q000633:toxicity*; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D009369:Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology*; D034741:RNA, Small Interfering / Q000502:physiology*; D016159:Tumor Suppressor Protein p53 / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000172:deficiency*
D000970:Antineoplastic Agents; D019313:BRCA1 Protein; D024682:BRCA2 Protein; D034741:RNA, Small Interfering; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D002945:Cisplatin