Germline polymorphisms in SIPA1 are associated with metastasis and other indicators of poor prognosis in breast cancer.
BACKGROUND
There is growing evidence that heritable genetic variation modulates metastatic efficiency. Our previous work using a mouse mammary tumor model has shown that metastatic efficiency is modulated by the GTPase-activating protein encoded by Sipa1 ('signal-induced proliferation-associated gene 1'). The aim of this study was to determine whether single nucleotide polymorphisms (SNPs) within the human SIPA1 gene are associated with metastasis and other disease characteristics in breast cancer.


METHODS
The study population (n = 300) consisted of randomly selected non-Hispanic Caucasian breast cancer patients identified from a larger population-based series. Genomic DNA was extracted from peripheral leukocytes. Three previously described SNPs within SIPA1 (one within the promoter [-313G>A] and two exonic [545C>T and 2760G>A]) were characterized using SNP-specific PCR.


RESULTS
The variant 2760G>A and the -313G>A allele were associated with lymph node involvement (P = 0.0062 and P = 0.0083, respectively), and the variant 545C>T was associated with estrogen receptor negative tumors (P = 0.0012) and with progesterone negative tumors (P = 0.0339). Associations were identified between haplotypes defined by the three SNPs and disease progression. Haplotype 3 defined by variants -313G>A and 2760G>A was associated with positive lymph node involvement (P = 0.0051), and haplotype 4 defined by variant 545C>T was associated with estrogen receptor and progesterone receptor negative status (P = 0.0053 and P = 0.0199, respectively).


CONCLUSIONS
Our findings imply that SIPA1 germline polymorphisms are associated with aggressive disease behavior in the cohort examined. If these results hold true in other populations, then knowledge of SIPA1 SNP genotypes could potentially enhance current staging protocols.
Laboratory of Population Genetics, National Cancer Institute/National Institutes of Health, Bethesda, Maryland, USA.
Nigel P S
NP
Crawford
Argyrios
A
Ziogas
David J
DJ
Peel
James
J
Hess
Hoda
H
Anton-Culver
Kent W
KW
Hunter
D000022:Abortion, Spontaneous / Q000453:epidemiology; D000032:Abortion, Therapeutic / Q000706:statistics & numerical data; D001943:Breast Neoplasms / Q000235:genetics* / Q000401:mortality; D005260:Female; D020690:GTPase-Activating Proteins / Q000235:genetics*; D019398:Genes, BRCA1; D024522:Genes, BRCA2; D018095:Germ-Line Mutation; D006801:Humans; D008875:Middle Aged; D009687:Nuclear Proteins / Q000235:genetics*; D011110:Polymorphism, Genetic; D011247:Pregnancy; D011379:Prognosis; D017211:Treatment Failure
D020690:GTPase-Activating Proteins; D009687:Nuclear Proteins; C490403:SIPA1 protein, human