title: Analysis of mitochondrial DNA in Tibetan gastric cancer patients at high altitude.
abstract: The highest risk areas of gastric cancer are currently Japan, Korea and China; Qinghai, a high-altitude area, has one of the highest gastric cancer rates in China. The incidence of gastric cancer is higher in the Tibetan ethnic group compared to that in the Han ethnic group in Qinghai. This study was conducted to determine the clinical characteristics of mitochondrial DNA (mtDNA) mutations and copy numbers among Tibetans with gastric cancer residing at high altitudes and investigate the association between adaptations to hypoxic conditions and oncogenesis. A total of 23 Tibetan gastric cancer patients and 40 matched controls were recruited in this study. Leukocyte mtDNA genes and copy numbers were analyzed. The haplogroups were classified based on mitochondrial gene sequences. A total of 56.5% of the study participants had used alcohol at some point in their lives and 73.9% were positive forHelicobacter pylori(H. pylori). Eight mutations in 8 mitochondrial genes were identified in 43.4% of the Tibetan cancer patient group. There were no significant differences in leukocyte mtDNA copy number levels based on smoking status, alchohol consumption, obesity orH. pyloriinfection between the control and cancer groups. Statistical differences were also not found between gastric cancer patients with and those without mtDNA mutations. The majority of Tibetan patients with gastric cancer belonged to the mitochondrial haplogroup M9. In conclusion, Tibetans with gastric cancer residing at high altitudes exhibited a wide spectrum of mtDNA mutations. However, leukocyte mtDNA copy numbers in stage II gastric cancer were not statistically different compared to those in healthy Tibetans.
authors.affiliation: Research Center for High Altitude Medicine, Qinghai University, Xining, Qinghai 810001, P.R. China ; Department of Oncology, Affiliated Hospital of Qinghai University, Xining, Qinghai 810001, P.R. China.
authors.forename: Jun
authors.initials: J
authors.lastname: Jiang
authors.affiliation: Department of Oncology, Affiliated Hospital of Qinghai University, Xining, Qinghai 810001, P.R. China.
authors.forename: Jun-Hui
authors.initials: JH
authors.lastname: Zhao
authors.affiliation: Department of Surgery, Affiliated Hospital of Qinghai University, Xining, Qinghai 810001, P.R. China.
authors.forename: Xue-Lian
authors.initials: XL
authors.lastname: Wang
authors.affiliation: Department of Oncology, Affiliated Hospital of Qinghai University, Xining, Qinghai 810001, P.R. China.
authors.forename: J I
authors.initials: JI
authors.lastname: DI
authors.affiliation: Department of Oncology, Affiliated Hospital of Qinghai University, Xining, Qinghai 810001, P.R. China.
authors.forename: Zhi-Bo
authors.initials: ZB
authors.lastname: Liu
authors.affiliation: Department of Oncology, Affiliated Hospital of Qinghai University, Xining, Qinghai 810001, P.R. China.
authors.forename: Guo-Yuan
authors.initials: GY
authors.lastname: Li
authors.affiliation: Department of Oncology, Affiliated Hospital of Qinghai University, Xining, Qinghai 810001, P.R. China.
authors.forename: Miao-Zhou
authors.initials: MZ
authors.lastname: Wang
authors.affiliation: Department of Oncology, Affiliated Hospital of Qinghai University, Xining, Qinghai 810001, P.R. China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Oncology, Affiliated Hospital of Qinghai University, Xining, Qinghai 810001, P.R. China.
authors.forename: Rong
authors.initials: R
authors.lastname: Chen
authors.affiliation: Research Center for High Altitude Medicine, Qinghai University, Xining, Qinghai 810001, P.R. China.
authors.forename: Ri-Li
authors.initials: RL
authors.lastname: Ge
keywords: Tibetan; gastric cancer; hypoxia; mtDNA copy number