BRM Promoter Polymorphisms and Survival of Advanced Non-Small Cell Lung Cancer Patients in the Princess Margaret Cohort and CCTG BR.24 Trial.
Introduction:BRM, a key catalytic subunit of the SWI/SNF chromatin remodeling complex, is a putative tumor susceptibility gene that is silenced in 15% of non-small cell lung cancer (NSCLC). Two novelBRMpromoter polymorphisms (BRM-741 andBRM-1321) are associated with reversible epigenetic silencing of BRM protein expression.Experimental Design:Advanced NSCLC patients from the Princess Margaret (PM) cohort study and from the CCTG BR.24 clinical trial were genotyped forBRMpromoter polymorphisms. Associations ofBRMvariants with survival were assessed using log-rank tests, the method of Kaplan and Meier, and Cox proportional hazards models. Promoter swap, luciferase assays, and chromatin immunoprecipitation (ChIP) experiments evaluated polymorphism function.In silicoanalysis of publicly available gene expression datasets with outcome were performed.Results:Carrying the homozygous variants of both polymorphisms ("double homozygotes", DH) when compared with those carrying the double wild-type was associated with worse overall survival, with an adjusted hazard ratios (aHR) of 2.74 (95% CI, 1.9-4.0). This was confirmed in the BR.24 trial (aHR, 8.97; 95% CI, 3.3-18.5). Lower BRM gene expression (by RNA-Seq or microarray) was associated with worse outcome (P< 0.04). ChIP and promoter swap experiments confirmed binding of MEF2D and HDAC9 only to homozygotes of each polymorphism, associated with reduced promoter activity in the DH.Conclusions:Epigenetic regulatory molecules bind to twoBRMpromoter sequence variants but not to their wild-type sequences. These variants are associated with adverse overall and progression-free survival. Decreased BRM gene expression, seen with these variants, is also associated with worse overall survival.Clin Cancer Res; 23(10); 2460-70. ©2016 AACR.
Princess Margaret Cancer Centre and University Health Network, University of Toronto, Toronto, Ontario, Canada. geoffrey.liu@uhn.ca.|Ontario Cancer Institute, Toronto, Ontario, Canada.
Geoffrey
G
Liu
Princess Margaret Cancer Centre and University Health Network, University of Toronto, Toronto, Ontario, Canada.
Sinead
S
Cuffe
University of Florida, Gainesville, Florida.
Shermi
S
Liang
Princess Margaret Cancer Centre and University Health Network, University of Toronto, Toronto, Ontario, Canada.|Ontario Cancer Institute, Toronto, Ontario, Canada.
Abul Kalam
AK
Azad
Princess Margaret Cancer Centre and University Health Network, University of Toronto, Toronto, Ontario, Canada.
Lu
L
Cheng
Princess Margaret Cancer Centre and University Health Network, University of Toronto, Toronto, Ontario, Canada.
Yonathan
Y
Brhane
Princess Margaret Cancer Centre and University Health Network, University of Toronto, Toronto, Ontario, Canada.
Xin
X
Qiu
Princess Margaret Cancer Centre and University Health Network, University of Toronto, Toronto, Ontario, Canada.|Ontario Cancer Institute, Toronto, Ontario, Canada.
David W
DW
Cescon
Princess Margaret Cancer Centre and University Health Network, University of Toronto, Toronto, Ontario, Canada.|Ontario Cancer Institute, Toronto, Ontario, Canada.
Jeffrey
J
Bruce
Princess Margaret Cancer Centre and University Health Network, University of Toronto, Toronto, Ontario, Canada.|Ontario Cancer Institute, Toronto, Ontario, Canada.
Zhuo
Z
Chen
Princess Margaret Cancer Centre and University Health Network, University of Toronto, Toronto, Ontario, Canada.|Ontario Cancer Institute, Toronto, Ontario, Canada.
Dangxiao
D
Cheng
Princess Margaret Cancer Centre and University Health Network, University of Toronto, Toronto, Ontario, Canada.|Ontario Cancer Institute, Toronto, Ontario, Canada.
Devalben
D
Patel
Princess Margaret Cancer Centre and University Health Network, University of Toronto, Toronto, Ontario, Canada.|Ontario Cancer Institute, Toronto, Ontario, Canada.
Brandon C
BC
Tse
Ottawa Hospital Cancer Centre, Ottawa, Ontario, Canada.
Scott A
SA
Laurie
Ottawa Hospital Cancer Centre, Ottawa, Ontario, Canada.
Glenwood
G
Goss
Princess Margaret Cancer Centre and University Health Network, University of Toronto, Toronto, Ontario, Canada.
Natasha B
NB
Leighl
Lunenfeld Research Institute and Mount Sinai Hospital, Toronto, Ontario, Canada.
Rayjean
R
Hung
Princess Margaret Cancer Centre and University Health Network, University of Toronto, Toronto, Ontario, Canada.
Penelope A
PA
Bradbury
Canadian Cancer Trials Group, Queens University, Kingston, Ontario, Canada.
Lesley
L
Seymour
Princess Margaret Cancer Centre and University Health Network, University of Toronto, Toronto, Ontario, Canada.|Ontario Cancer Institute, Toronto, Ontario, Canada.
Frances A
FA
Shepherd
Princess Margaret Cancer Centre and University Health Network, University of Toronto, Toronto, Ontario, Canada.|Ontario Cancer Institute, Toronto, Ontario, Canada.
Ming Sound
MS
Tsao
Canadian Cancer Trials Group, Queens University, Kingston, Ontario, Canada.
Bingshu E
BE
Chen
Princess Margaret Cancer Centre and University Health Network, University of Toronto, Toronto, Ontario, Canada.|Ontario Cancer Institute, Toronto, Ontario, Canada.
Wei
W
Xu
University of Florida, Gainesville, Florida.
David N
DN
Reisman
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000235:genetics* / Q000473:pathology; D042002:Chromatin Assembly and Disassembly / Q000235:genetics; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics; D018572:Disease-Free Survival; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D020022:Genetic Predisposition to Disease; D006655:Histone Deacetylases / Q000235:genetics; D006720:Homozygote; D006801:Humans; D064326:MEF2 Transcription Factors / Q000235:genetics; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics*
D002868:Chromosomal Proteins, Non-Histone; D064326:MEF2 Transcription Factors; C578043:MEF2D protein, human; D012097:Repressor Proteins; C084011:SMARCA2 protein, human; C445179:SWI-SNF-B chromatin-remodeling complex; D014157:Transcription Factors; C486544:HDAC9 protein, human; D006655:Histone Deacetylases