Li Ran, Wang Xuanyang, Zhang Yuntao, Xu Xiaoqing, Wang Lulu, Wei Chunbo, Liu Lin, Wang Ziqi, Li Ying
Department of Nutrition and Food Hygiene, the National Key Discipline, School of Public Health, Harbin Medical University, Harbin, China.
Front Oncol. 2022 Apr 14;12:852718. doi: 10.3389/fonc.2022.852718. eCollection 2022.
Tryptophan and its metabolites have been found related to various cancers, but the direction of this relationship is still unclear. The purpose of this study is to explore the causal associations of tryptophan and kynurenine with multiple cancers based on the bidirectional Mendelian randomization analysis.
The data of a genome-wide association study meta-analysis on 7,824 individuals was used to explore the genetic variants strongly associated with tryptophan and kynurenine. Genetic instruments of four specific cancers were obtained from available summary-level data of 323,590 European participants. Bidirectional Mendelian randomization analysis was conducted to examine possible causality. Sensitivity analysis was performed to test heterogeneity and horizontal pleiotropy. COX regression analysis was conducted to explore associations between dietary tryptophan and cancer mortality in NHANES 1988-1994.
No evidence of any causal association of tryptophan and kynurenine with the risk of four specific cancers was shown, except for weak correlations were suggested between lung or prostate cancer and kynurenine. Multiple sensitivity analyses generated similar results. Our findings from COX regression analysis were consistent with the above results.
Our study did not find any causal relationship between tryptophan and kynurenine and multiple cancers. The associations still need further research.
已发现色氨酸及其代谢产物与多种癌症有关，但这种关系的方向仍不明确。本研究的目的是基于双向孟德尔随机化分析，探讨色氨酸和犬尿氨酸与多种癌症之间的因果关联。
利用一项对7824名个体的全基因组关联研究荟萃分析的数据，探索与色氨酸和犬尿氨酸密切相关的基因变异。从323590名欧洲参与者的现有汇总水平数据中获取四种特定癌症的遗传工具变量。进行双向孟德尔随机化分析以检验可能的因果关系。进行敏感性分析以测试异质性和水平多效性。在1988 - 1994年美国国家健康与营养检查调查（NHANES）中进行COX回归分析，以探讨膳食色氨酸与癌症死亡率之间的关联。
未显示色氨酸和犬尿氨酸与四种特定癌症风险存在任何因果关联的证据，除了肺癌或前列腺癌与犬尿氨酸之间存在微弱相关性。多项敏感性分析得出了相似的结果。我们COX回归分析的结果与上述结果一致。
我们的研究未发现色氨酸和犬尿氨酸与多种癌症之间存在任何因果关系。这种关联仍需进一步研究。
