Soy Intake May Adversely Affect Gene Expression in Early Breast Cancer
Soya tüketiminin yararlarından ve kansere karşı koruyucu etkinliğinden fısıltı gazetelerinden sık bahsedilir. Bu ideaya, özelikle soya tüketiminin yaygın olduğu uzak Asyalı kadınlarda meme kanseri oranın düşük olması ile soya tüketimi arasındaki ilişkinin olduğu düşünülmesi ile inandırıcılığı artırmaktadır. Fakat unutulan ve göz ardı edilen meme kanserindeki ırksal faktörler ve soya ve ürünlerinin genetik orijine bağlı göstereceği etkinliğin farklı olduğudur. Bu konuda Amerika da yapılan güzel bir çalışma noktayı koymuştur.
Journal of the National Cancer Institute, dergisinde çıkan çalışmaya göre, soya alanlarda, genistein adı verilen östrojen benzeri madenin yüksek olduğu saptanmış.
Soya alanlarda ve genistein düzeyi yüksek olanlarda, hücre çoğalmasında etkinliği olan FGFR2 genin aktivasyonunda artma saptanmış.
Soya tüketimi ırksal temelde farklılık gösterebilir. Bu bilgi ışığında tüketilmesine dikkat edilmelidir.
Sonuç: Bu çalışma bazı kadınlara soya tüketmenin kanser gelişimini hızlandırabileceğini göstermiştir.
Kaynak:Currently reading http://www.ascopost.com/viewnews.aspx?nid=18621 …
Soy Intake May Adversely Affect Gene Expression in Early Breast Cancer
By Matthew Stenger
Posted: 9/26/2014 4:40:54 PM
Last Updated: 9/26/2014 4:40:54 PM
ADVERTISEMENT
Key Points:
• Soy supplementation was associated with differential expression of numerous genes.
• Increased expression of genes that drive cell cycle and proliferation pathways, including FGFR2, was found for high- vs low-genistein levels.
In a randomized study reported in theJournal of the National Cancer Institute, Shike et al found that soy supplementation resulting in high genistein levels was associated with overexpression of the tumorigenic growth factor receptor FGFR2 and genes that drive cell cycle and proliferation pathways.
Study Details
In the study, 140 women with early-stage breast cancer were randomly assigned to receive soy protein supplementation (25.8 g soy protein powder twice a day, n = 70) or placebo (25.8 g milk protein twice a day, n = 70) for 7 to 30 days from diagnosis until surgery. Adherence was determined by the plasma isoflavones genistein and daidzein, the major phytoestrogens of soy. Gene expression changes were evaluated by NanoString in pre- and post-treatment tumor samples. Genome-wide expression analysis was performed on post-treatment samples, and proliferation (Ki67) and apoptosis (Cas3) were measured by immunohistochemistry.
Differential Expression
Plasma isoflavone levels increased in the soy group (P .001) and did not change in the placebo group. In paied analysis of pre- and post-treatment samples, 21 genes out of 202 examined showed altered expression (all P .05). Several genes exhibited different magnitude and direction of expression changes in the two groups. For example, expression of FANCC and UGT2A1 increased in 7.5% of tumors in the soy group and decreased in the control group.
Analysis by Genistein Level
On the hypothesis that genistein plasma levels, rather than assignment to the soy group, might be a more accurate marker of genistein effects on gene expression, differential expression was examined according to high plasma genistein level. Median genistein concentration in the soy group was 6.3 ng/mL, and 25% had very low levels ( 16 ng/mL, corresponding to the 95th percentile concentration in the placebo group. A high-genistein signature consisting of 126 differentially expressed genes was identified, including 47 overexpressed and 79 underexpressed genes. This signature was characterized by greater than twofold overexpression of cell cycle transcripts, including overexpression of genes that promote cell proliferation, such as FGFR2, E2F5, BUB1, CCNB2, MYBL2, CDK1, and CDC20 (all P < .01). Soy intake was not associated with significant changes in Ki67 or Cas3.
The investigators concluded: “Gene expression associated with soy intake and high plasma genistein defines a signature characterized by overexpression of FGFR2 and genes that drive cell cycle and proliferation pathways. These findings raise the concerns that in a subset of women soy could adversely affect gene expression in breast cancer.”
Moshe Shike, MD, of Memorial Sloan Kettering Cancer Center, is the corresponding author for theJournal of the National Cancer Institute article.
The study was supported by a grant from the Breast Cancer Research Foundation. The study authors reported no potential conflicts of interest.
