title: Genetic and dietary determinants of insulin-like growth factor (IGF)-1 and IGF binding protein (BP)-3 levels among Chinese women.
abstract: BACKGROUND
  Higher insulin-like growth factor (IGF)-1 and lower IGF binding protein (BP)-3 levels have been associated with higher commoncancer risk, including breast cancer. Dietary factors, genetic polymorphisms, and the combination of both may influence circulating IGF-1 and IGFBP-3 serum concentrations.
  
  
  METHODS
  From September 2011 to July 2012, we collected demographic, reproductive and dietary data on 143 women (≥ 40 years). We genotyped IGF-1 rs1520220 and IGFBP-3 rs2854744 and measured circulating IGF-1 and IGFBP-3 levels in serum. Covariance analyses were used to estimate the associations of serum levels of IGF-1 and IGFBP-3, and the molar ratio of IGF-1 to IGFBP-3 with IGF-1 rs1520220 and IGFBP-3 rs2854744 genotypes. We subsequently assessed the combined influence of genetics and diet (daily intake of protein, fat and soy isoflavones) on IGF-1 and IGFBP-3 levels.
  
  
  RESULTS
  Among women aged less than 50 years, circulating IGF-1 serum levels were significantly lower for those with CC genotype for IGF-1 rs1520220 than levels for those with the GC or GG genotypes (in recessive model: P = 0.007).In gene-diet analyses among these women, we found carrying CC genotype for IGF-1 rs1520220 and high soy isoflavone intake tend to be associated with lower circulating IGF-1 levels synthetically (P = 0.002). Women with GG or GC genotypes for IGF-1 rs1520220 and with low intake of soy isoflavones had the highest levels of circulating IGF-1 (geometric mean [95% CI]: 195 [37, 1021] µg/L). Comparatively, women with both the CC genotype and high soy intake had the lowest levels of circulating IGF-1 (geometric mean [95% CI]: 120 [38,378] µg/L).
  
  
  CONCLUSIONS
  IGF-1 serum levels are significantly lower among women with the CC genotype for IGF-1-rs1520220. High soy isoflavone intake may interact with carrying CC genotype for IGF-1-rs1520220 to lower women's serum IGF-1 levels more.
authors.affiliation: Department of Epidemiology and Biostatistics, West China School of Public Health, Sichuan University, Chengdu, P.R. China; Department of Health Service Management, Public Health School, Sun Yat-Sen University, Guangzhou, Guangdong, China.
authors.forename: Qiong
authors.initials: Q
authors.lastname: Wang
authors.affiliation: The Comprehensive Guidance Center of Women's Health, Chengdu Women's and Children's Central Hospital, Chengdu, P.R. China.
authors.forename: Li
authors.initials: L
authors.lastname: Liu
authors.affiliation: Department of Epidemiology and Biostatistics, West China School of Public Health, Sichuan University, Chengdu, P.R. China.
authors.forename: Hui
authors.initials: H
authors.lastname: Li
authors.affiliation: Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina, United States of America.
authors.forename: Lauren E
authors.initials: LE
authors.lastname: McCullough
authors.affiliation: Department of Epidemiology and Biostatistics, West China School of Public Health, Sichuan University, Chengdu, P.R. China.
authors.forename: Ya-na
authors.initials: YN
authors.lastname: Qi
authors.affiliation: Department of Epidemiology and Biostatistics, West China School of Public Health, Sichuan University, Chengdu, P.R. China; Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina, United States of America.
authors.forename: Jia-yuan
authors.initials: JY
authors.lastname: Li
authors.affiliation: The Comprehensive Guidance Center of Women's Health, Chengdu Women's and Children's Central Hospital, Chengdu, P.R. China.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina, United States of America.
authors.forename: Erline
authors.initials: E
authors.lastname: Miller
authors.affiliation: Department of Epidemiology and Biostatistics, West China School of Public Health, Sichuan University, Chengdu, P.R. China.
authors.forename: Chun-xia
authors.initials: CX
authors.lastname: Yang
authors.affiliation: Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina, United States of America; Lineberger Comprehensive Cancer Center, Chapel Hill, North Carolina, United States of America.
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: Smith
mesh_terms: D000293:Adolescent; D000328:Adult; D044466:Asian People / Q000235:genetics*; D002681:China; D003710:Demography; D004032:Diet; D005260:Female; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood / Q000235:genetics*; D007334:Insulin-Like Growth Factor I / Q000235:genetics*; D007529:Isoflavones / Q000494:pharmacology; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide; D012098:Reproduction
chemical_list: D018972:Insulin-Like Growth Factor Binding Protein 3; D007529:Isoflavones; D007334:Insulin-Like Growth Factor I