Lin Kun, Shen Wenying, Shen Zhongying, Cai Shushen, Wu Yongning
Shantou University Medical College, 22 Xin Ling Road, Shantou 515041, People's Republic of China.
Int J Cancer. 2003 Dec 20;107(6):891-5. doi: 10.1002/ijc.11506.
We studied 2 counties in southern China, which are close to each other but show very different mortality rates from esophageal cancer. We collected 12 hr urine samples and analyzed them for NPRO, other nitrosamino acids, nitrate and ASC. The potential for forming NPRO and the effect on inhibition by ASC were recorded. Urine was collected after (i) no treatment, (ii) a dose of proline and (iii) proline with ASC. Intake and excretion of nitrate were significantly greater in the high-risk area. After the proline dose, urinary excretion of NPRO was significantly greater in the high-risk area. The inhibitory effect of ASC after taking it with proline was less in the high-risk area. Hence, the high-risk area showed greater potential for forming NPRO, and this formation was less inhibited by ASC. This supports the view that esophageal cancer in this area may be caused by nitrosamines formed in vivo, perhaps from nitrite produced by reduction of ingested nitrate.
我们研究了中国南方两个相邻的县，这两个县食管癌死亡率差异很大。我们收集了12小时尿液样本，并分析其中的N-亚硝基脯氨酸（NPRO）、其他亚硝基氨基酸、硝酸盐和抗坏血酸（ASC）。记录了形成NPRO的可能性以及ASC的抑制作用。在以下三种情况下收集尿液：（i）未处理；（ii）给予一定剂量的脯氨酸；（iii）脯氨酸与ASC一起给予。高危地区硝酸盐的摄入量和排泄量明显更高。给予脯氨酸剂量后，高危地区NPRO的尿排泄量明显更高。高危地区脯氨酸与ASC一起服用后ASC的抑制作用较小。因此，高危地区显示出形成NPRO的更大可能性，并且这种形成受ASC的抑制较小。这支持了该地区食管癌可能由体内形成的亚硝胺引起的观点，亚硝胺可能来自摄入硝酸盐还原产生的亚硝酸盐。
