Shao Chunlin, Aoki Mizuho, Furusawa Yoshiya
Heavy-Ion Radiobiology Research Group, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage, 263-8555 Chiba, Japan.
Radiat Environ Biophys. 2003 Oct;42(3):183-7. doi: 10.1007/s00411-003-0202-y. Epub 2003 Aug 15.
The bystander effect on unirradiated neoplastic human salivary gland (HSGc) cells was investigated by co-culturing them with HSGc cells that had been irradiated with 290 MeV/u carbon beams of different linear energy transfer (LET) values. It was found that the plating efficiency and proliferation of the unirradiated recipient cells were increased and that these increases were related to the LET as well as the radiation dose. Exposure of HSGc cells to higher LET and higher dose was much more effective in enhancing the plating efficiency and proliferation of the unirradiated cells than exposure to lower LET and lower dose. However, when PTIO, a nitric oxide (NO)-specific scavenger, was present in the co-culture medium, the cell growth capacity of the unirradiated recipients was reduced to control level, indicating that NO is involved in the bystander response. As an oxidation product of NO, nitrite was detected in the co-culture medium and its concentration depended on the LET and dose of irradiation. Using a NO-generator sper/NO, it was verified that NO at low concentrations indeed enhanced cell proliferation. Accordingly, NO plays an important role in medium-mediated bystander effects.
通过将未受辐照的人肿瘤性唾液腺（HSGc）细胞与用不同线性能量传递（LET）值的290 MeV/u碳离子束辐照过的HSGc细胞共培养，研究了旁观者效应。结果发现，未受辐照的受体细胞的接种效率和增殖增加，且这些增加与LET以及辐射剂量有关。与低LET和低剂量相比，将HSGc细胞暴露于高LET和高剂量下，在提高未受辐照细胞的接种效率和增殖方面更为有效。然而，当共培养基中存在一氧化氮（NO）特异性清除剂PTIO时，未受辐照受体的细胞生长能力降低至对照水平，表明NO参与了旁观者反应。作为NO的氧化产物，在共培养基中检测到了亚硝酸盐，其浓度取决于辐照的LET和剂量。使用NO发生器sper/NO证实，低浓度的NO确实能促进细胞增殖。因此，NO在介质介导的旁观者效应中起重要作用。
