title: Noninvasive evaluation of radiation-enhanced glioma cells invasiveness by ultra-high-field (1)H-MRS in vitro.
abstract: Glioma is the most common type of the primary CNS tumor. Radiotherapy is an important treatment measure after surgery. However, its highly invasive character is the main reason of postoperative recurrence. The aim of the study was to probe the correlation between the invasion ability and the metabolite characteristics of glioma cells at the cellular level after irradiation by using 14.7T high-resolution nuclear proton magnetic resonance spectroscopy ((1)H-MRS).
  
  
  
  To determine the matrix metalloproteinase-2 (MMP-2) activity and metabolite ratios of glioma cells after irradiation with different doses of X-rays, U87 and C6 glioma cells were exposed to X-ray irradiation of 0, 1, 5, 10, and 15Gy. After 20h, the perchloric acid (PCA) extraction method was used to evaluate water-soluble metabolites [choline (Cho), creatine (Cr), and N-acetylaspartate (NAA)], and (1)H-MRS patterns and changes in metabolite ratios were observed in vitro by 14.7T high resolution (1)H-MRS. Matrigel invasion assays and gelatin zymography were performed to test the invasion ability of U87 and C6 glioma cells.
  
  
  
  Good MR spectra were obtained from PCA method extracts of U87 and C6 glioma cells. Both radiation-induced MMP-2 activity and the Cho/Cr and Cho/NAA ratios increased after irradiation, and their increase occurred in a dose-dependent manner. The MMP-2 activity and the Cho/Cr and Cho/NAA ratios of glioma cells increased after irradiation up to 10Gy and decreased thereafter. In particular, the Cho/NAA ratio of U87 cells increased from 3.55±0.06 (0Gy) to 9.13±0.30 (10Gy) and then declined to 5.94±0.15 (15Gy). Furthermore, the invasion ability of glioma cells had a strong positive correlation with the Cho/Cr and Cho/NAA ratios. Both the Cho/Cr ratio and the Cho/NAA ratio of U87 glioma cells were highly positively correlated with the number of invading cells in the Matrigel invasion assay. The Pearson's correlation coefficient (r) values of U87 cells were 0.89 (Cho/Cr ratio versus invasion ability) and 0.91 (Cho/NAA ratio versus invasion ability) (P<0.01). C6 cells exhibited similar changes to those of U87 cells.
  
  
  
  In vitro high-resolution (1)H-MRS is useful for detecting glioma invasiveness at the cellular level.
authors.affiliation: Department of Radiology, Qilu Hospital of Shandong University, Jinan, China.
authors.forename: Yan-Jie
authors.initials: YJ
authors.lastname: Xu
authors.affiliation: Department of Radiology, Qilu Hospital of Shandong University, Jinan, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Cui
authors.affiliation: Department of Radiology, Qilu Hospital of Shandong University, Jinan, China.
authors.forename: Hong-Xia
authors.initials: HX
authors.lastname: Li
authors.affiliation: Department of Radiology, Qilu Hospital of Shandong University, Jinan, China.
authors.forename: Wen-Qi
authors.initials: WQ
authors.lastname: Shi
authors.affiliation: Department of Radiology, Qilu Hospital of Shandong University, Jinan, China.
authors.forename: Fu-Yan
authors.initials: FY
authors.lastname: Li
authors.affiliation: Department of Radiotherapy, Qilu Hospital of Shandong University, Jinan, China.
authors.forename: Jian-Zheng
authors.initials: JZ
authors.lastname: Wang
authors.affiliation: Department of Radiology, Qilu Hospital of Shandong University, Jinan, China. Electronic address: zengqingshi@sdu.edu.cn.
authors.forename: Qing-Shi
authors.initials: QS
authors.lastname: Zeng
mesh_terms: D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D001932:Brain Neoplasms / Q000378:metabolism* / Q000473:pathology*; D018929:Cell Culture Techniques; D045744:Cell Line, Tumor; D002470:Cell Survival; D002794:Choline / Q000378:metabolism; D003401:Creatine / Q000378:metabolism; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005910:Glioma / Q000378:metabolism* / Q000473:pathology*; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D009361:Neoplasm Invasiveness; D066244:Proton Magnetic Resonance Spectroscopy / Q000379:methods*; D011836:Radiation Tolerance; D014965:X-Rays
chemical_list: D001224:Aspartic Acid; C000179:N-acetylaspartate; D020778:Matrix Metalloproteinase 2; D003401:Creatine; D002794:Choline
keywords: (1)H-MRS; Glioma; MMP-2; invasiveness; perchloric acid extracts; radiation therapy