[MnSOD gene regulated by aminopeptidase N promoter specifically protects bone marrow from radiation].
OBJECTIVE
It is an effective way to induce radio-tolerant gene into hematopoietic cells in bone marrow for overcoming the suppression of radiotherapy on hematopoietic system. However, this also increases the radiation tolerance of tumor cells. This study was designed to investigate a method to specifically protect bone marrow cell from being damaged by radiation, along without increasing resistance of tumor cell to radiation.


METHODS
The retrovirus vector of manganese superoxide dismutase (MnSOD) gene regulated by aminopeptidase N (APN) bone marrow-specific gene promoter was constructed and induced into myeloblastic KG1a and cancer cell BEL7402. MnSOD mRNA level was analyzed by PT-PCR; MnSOD activity in the cells was determined; the sensitivity of bone marrow cell and hepatic carcinoma cell to x-ray was detected by cell survival test; the cell apoptosis was analyzed with flow cytometry and fractural DNA electrophoresis.


RESULTS
The MnSOD mRNA level and enzyme activity in KG1a cells transferred with the gene was obviously increased. Expression of MnSOD mRNA drove by APN myelo-specific promoter effectively inhibited apoptosis of KG1a cells induced by radiation and endowed KG1a cell line with the enhancement of tolerance to radiation, which increased by 3.7 folds compared to parental cells at the dose of 10 Gy. In contrast, the level of MnSOD mRNA, the enyme activity of MnSOD and the radiosensitivity had no significant change in BEL 7402 cells transduced with MnSOD gene.


CONCLUSIONS
APN bone marrow-specific promoter could control MnSOD gene expression highly in myeloid cell and lower in cancer cell. In the process of killing of cancer cell by x-ray, MnSOD gene regulated by APN bone marrow-specific promoter could specifically protect myeloid cell. This study provides a new clue to solve the bone marrow suppression in high dose radiotherapy.
Liang
Li-bo
LB
Cancer Institute, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing 100021, P. R. China.
Ma
Ye-wei
YW
Zhao
Qing-zheng
QZ
Zhou
Xiao-shan
XS
Yang
Jun
J
Li
Yan-chun
YC
Liu
Yu-ying
YY
Wang
Zheng
Z
Zhagn
Yang-pei
YP
D016475:3T3 Cells; D000818:Animals; D017209:Apoptosis / Q000528:radiation effects; D001854:Bone Marrow Cells / Q000378:metabolism / Q000528:radiation effects*; D018826:CD13 Antigens / Q000235:genetics*; D002460:Cell Line; D002470:Cell Survival / Q000528:radiation effects; D053938:DNA Fragmentation / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D051379:Mice; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013482:Superoxide Dismutase / Q000235:genetics* / Q000502:physiology; D014162:Transfection; D014407:Tumor Cells, Cultured
D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D013482:Superoxide Dismutase; D018826:CD13 Antigens