title: Sublethal dose of irradiation enhances invasion of malignant glioma cells through p53-MMP 2 pathway in U87MG mouse brain tumor model.
abstract: BACKGROUND
  Glioblastoma is a highly lethal neoplasm that frequently recurs locally after radiotherapy, and most of these recurrences originate from near the irradiated target field. In the present study, we identified the effects of radiation on glioma invasion and p53, TIMP-2, and MMP-2 expression through in vitro and in vivo experiments.
  
  
  METHODS
  The U87MG (wt p53) and U251 (mt p53) human malignant glioma cell lines were prepared, and the U2OS (wt 53) and Saos2 (del p53) osteosarcoma cell lines were used as p53 positive and negative controls. The four cell lines and p53 knock-downed U87MG cells received radiation (2-6 Gy) and were analyzed for expression of p53 and TIMP-2 by Western blot, and MMP-2 activity was detected by zymography. In addition, the effects of irradiation on directional invasion of malignant glioma were evaluated by implanting nude mice with bioluminescent u87-Fluc in vivo followed by MMP-2, p53, and TIMP-2 immunohisto-chemistry and in situ zymography.
  
  
  RESULTS
  MMP-2 activity and p53 expression increased in proportional to the radiation dose in cell lines with wt p53, but not in the cell lines with del or mt p53. TIMP-2 expression did not increase in U87MG cells. MMP-2 activity decreased in p53 knock-downed U87MG cells but increased in the control group. Furthermore, radiation enhanced MMP-2 activity and increased tumor margin invasiveness in vivo. Tumor cells invaded by radiation overexpressed MMP-2 and p53 and revealed high gelatinolytic activity compared with those of non-radiated tumor cells.
  
  
  CONCLUSIONS
  Radiation-induced upregulation of p53 modulated MMP-2 activity, and the imbalance between MMP-2 and TIMP-2 may have an important role in glioblastoma invasion by degrading the extracellular matrix. Bioluminescent "U87-Fluc"was useful for observing tumor formation without sacrifice after implanting tumor cells in the mouse brain. These findings suggest that the radiotherapy involved field for malignant glioma needs to be reconsidered, and that future trials should investigate concurrent pharmacologic therapies that inhibit invasion associated with radiotherapy.
authors.affiliation: Department of Neurosurgery, Chonnam National University Hwasun Hospital and Mediacal School, 322 Seoyang-ro, Hwasun-eup, Hwasun-gun, Jeonnam, 519-763, Republic of Korea.
authors.forename: Jian
authors.initials: J
authors.lastname: Pei
authors.affiliation: Department of Neurosurgery, Chonnam National University Hwasun Hospital and Mediacal School, 322 Seoyang-ro, Hwasun-eup, Hwasun-gun, Jeonnam, 519-763, Republic of Korea.
authors.forename: In-Ho
authors.initials: IH
authors.lastname: Park
authors.affiliation: Brain Tumor Research Laboratory, and Chonnam National University Research Institute of Medical Sciences, Chonnam National University Hwasun Hospital and Medical School, 322 Seoyang-ro, Hwasun-eup, Hwasun-gun, Jeonnam, 519-763, Republic of Korea.
authors.forename: Hyang-Hwa
authors.initials: HH
authors.lastname: Ryu
authors.affiliation: Brain Tumor Research Laboratory, and Chonnam National University Research Institute of Medical Sciences, Chonnam National University Hwasun Hospital and Medical School, 322 Seoyang-ro, Hwasun-eup, Hwasun-gun, Jeonnam, 519-763, Republic of Korea.
authors.forename: Song-Yuan
authors.initials: SY
authors.lastname: Li
authors.affiliation: Brain Tumor Research Laboratory, and Chonnam National University Research Institute of Medical Sciences, Chonnam National University Hwasun Hospital and Medical School, 322 Seoyang-ro, Hwasun-eup, Hwasun-gun, Jeonnam, 519-763, Republic of Korea.
authors.forename: Chun-Hao
authors.initials: CH
authors.lastname: Li
authors.affiliation: Department of Neurosurgery, Chonnam National University Hwasun Hospital and Mediacal School, 322 Seoyang-ro, Hwasun-eup, Hwasun-gun, Jeonnam, 519-763, Republic of Korea.|Brain Tumor Research Laboratory, and Chonnam National University Research Institute of Medical Sciences, Chonnam National University Hwasun Hospital and Medical School, 322 Seoyang-ro, Hwasun-eup, Hwasun-gun, Jeonnam, 519-763, Republic of Korea.
authors.forename: Sa-Hoe
authors.initials: SH
authors.lastname: Lim
authors.affiliation: Brain Tumor Research Laboratory, and Chonnam National University Research Institute of Medical Sciences, Chonnam National University Hwasun Hospital and Medical School, 322 Seoyang-ro, Hwasun-eup, Hwasun-gun, Jeonnam, 519-763, Republic of Korea.
authors.forename: Min
authors.initials: M
authors.lastname: Wen
authors.affiliation: Department of Neurosurgery, Chonnam National University Hwasun Hospital and Mediacal School, 322 Seoyang-ro, Hwasun-eup, Hwasun-gun, Jeonnam, 519-763, Republic of Korea.
authors.forename: Woo-Youl
authors.initials: WY
authors.lastname: Jang
authors.affiliation: Department of Neurosurgery, Chonnam National University Hwasun Hospital and Mediacal School, 322 Seoyang-ro, Hwasun-eup, Hwasun-gun, Jeonnam, 519-763, Republic of Korea. sjung@jnu.ac.kr.|Brain Tumor Research Laboratory, and Chonnam National University Research Institute of Medical Sciences, Chonnam National University Hwasun Hospital and Medical School, 322 Seoyang-ro, Hwasun-eup, Hwasun-gun, Jeonnam, 519-763, Republic of Korea. sjung@jnu.ac.kr.
authors.forename: Shin
authors.initials: S
authors.lastname: Jung
mesh_terms: D000818:Animals; D015153:Blotting, Western; D001932:Brain Neoplasms / Q000378:metabolism / Q000473:pathology*; D045744:Cell Line, Tumor; D004195:Disease Models, Animal; D005910:Glioma / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D008297:Male; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009361:Neoplasm Invasiveness / Q000473:pathology; D034741:RNA, Small Interfering; D015398:Signal Transduction / Q000528:radiation effects*; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D023041:Xenograft Model Antitumor Assays
chemical_list: D034741:RNA, Small Interfering; D016159:Tumor Suppressor Protein p53; D020778:Matrix Metalloproteinase 2; C522362:Mmp2 protein, mouse