GENETICS : Amplification of oestrogen receptor gene in breast cancer

A fifth of breast tumours have extra copies of the gene encoding one form of the oestrogens receptor ESR1, suggests a study. A small-scale initial study shows that women treated with tamoxifen, which blocks the activity of the oestrogens receptor, survive longer if their tumour has this gene amplification.
Oestrogens receptor expression is one of the most important known factors in the development of breast cancer, and assessing its status is important for determining the use of anti-oestrogens receptor therapies like tamoxifen. Ronald Simon and colleagues examined more than 2,000 breast cancer samples for evidence of amplification of ESR1, and detected it in 20.6 % of the tumours. In a small follow-up study of 175 women with breast cancer who were being treated with tamoxifen, they found that women with the amplification survived longer than those who did not, even though the tumours in both groups of women expressed ESR1. The authors suggest that ESR1 amplification may identify a subgroup of breast cancers that would be particularly likely to respond to anti-oestrogens therapy.
Author contact:
Ronald Simon (University Medical Center Hamburg Eppendorf, Germany)
Tel: +49 42803 7214; E-mail: r.simon@uke.uni-hamburg.de



Natural genetic variant influencing rice grain weight

A study published in Nature Genetics this week identifies a gene that influences rice grain weight and yield. This is only the second such gene that has been found and functionally characterized, and is a step toward understanding and improving grain yield in crops.
Rice is a staple food, and the world’s most important cereal crop. Hong-Xuan Lin and colleagues examined two varieties of rice that exhibit significant differences in grain size, and mapped the gene responsible for this variation in size – GW2. The version of GW2 found in the large-grain variety of rice increased the width and weight of rice grains and increases grain yield per plant by nearly 20%, although the authors caution that its effect on grain yield needs to be further assessed in randomized blocks of plants in paddies.
Initial experiments also show that rice with the high-yield variant of GW2 has no reduction in cooking or eating quality, suggesting that it will be useful for high-yield crop breeding. GW2 encodes a protein that belongs to a family of enzymes that target other proteins for degradation, and the authors speculate that it could affect grain size by regulating the cell division cycle.
Author contact:
Hong-Xuan Lin (Shanghai Institute for Biological Sciences, China)
Tel: +86 21 5492 4129; E-mail: hxlin@sibs.ac.cn

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