Gut microbes spur liver cancer in obese mice,Nature, June 26th, 2013
肥胖老鼠肠道微生物引发肝癌,自然,2013年6月26日
The gut bacteria of obese mice unleash high levels of an acid that promotes liver cancer, reveals one of the first studies to uncover a mechanism for the link between obesity and cancer.
一项旨在揭示肥胖与癌症之间联系的研究发现，肥胖老鼠肠道微生物能大量释放一种能导致肝癌的酸。
Eijione Hara,one of the study authors, and his colleagues initially set out to study how dying cells influence obesity-linked cancers.
Eijione Hara是该项研究的研究人员之一，他和他的同事们开始这项研究的目的是为了发现即将死亡的细胞对与肥胖相关的癌症的影响。
Cells that are irrepairably damaged or pre-cancerous can become senescent — meaning that they stop dividing for overall health of the organism.
不可修复的受损细胞或癌变前细胞会成为衰老细胞，即这些细胞会停止为了维持机体健康而进行的分裂。
But before senescent cells die, they can spew out chemicals that may cause inflammation and promote cancer development.
但是在这些衰老细胞死亡之前，它们会释放出能够导致其他细胞产生炎症并进一步癌变的化学物质。
To examine whether senescent cells are involved in obesity-induced cancers, researchers worked with genetically engineered mice.
为了研究衰老细胞是否与肥胖诱发性癌症相关，研究人员使用转基因老鼠做实验。
Then they primed the mice by exposing them to a carcinogenic chemical, a process that Hara says may be similar to humans' exposure to environmental toxins, such as air pollution.
他们将这些老鼠放置到有致癌性化学物质的环境当中。Hara说这一过程同人类与环境中的有毒物质接触，例如空气污染，类似。
Researchers then fed the mice either a normal diet or a high-fat diet.
然后，研究人员用正常的食物喂一部分老鼠，用高脂肪食物喂另一部分。
After 30 weeks, only 5% of the lean mice developed cancer — in their lungs — whereas all the obese mice developed liver cancer.
30周之后，瘦老鼠当中只有百分之五患上了肺癌，而所有的肥胖老鼠都患上了肝癌。
Although the results showed that cell senescence was involved in obesity-linked cancer in the mice, researchers did not initially understand why the liver became a hotbed for tumours.
尽管结果显示细胞衰老是肥胖相关癌症的一个致病因素，但是研究人员刚开始并不理解为什么肝脏成为了癌变的高发部位。
But when they compared the blood serum of the two groups of mice,
但是当他们对比两组老鼠的血清是发现，
they found that the obese mice had much higher levels of deoxycholic acid (DCA), a chemical that causes DNA damage and can induce cell senescence.
肥胖老鼠的血清当中脱氧胆酸的含量远远高于瘦老鼠，脱氧胆酸是一种能够损害DNA并导致细胞衰老的物质。
The researchers also found that obese mice had a greater number of DCA-producing Clostridium bacteria,
研究人员还发现肥胖老鼠体内能制造脱氧胆酸的梭状芽胞杆菌较多，
and that obese mice given antibiotics to clear intestinal bacteria developed fewer liver tumours.Thank you.
并且如果用抗生素为它们清除肠道细菌，它们患上肝癌的几率会降低。谢谢。
