Zhang Yong-Chun, Jiang Gang, Gao Han, Liu Hua-Min, Liang Jun
Oncology Department, the Affiliated Hospital of Qingdao University, Qingdao, China E-mail :
Asian Pac J Cancer Prev. 2014;15(5):2353-8. doi: 10.7314/apjcp.2014.15.5.2353.
We aimed to detect the expression of HIF-1α, VEGF, HPSE-1 and CD31 in SKOV3 xenografts in nude mice treated with different doses of ionizing radiation, trying to explore the possible mechanism of hypoxia and radioresistance.
Nude mice bearing SKOV3 xenografts were randomly divided into 4 groups: Group A (control group, no ionizing radiation), Group B (treated with low dose of ionizing radiation: 50cGy), Group C (treated with high dose of ionizing radiation: 300cGy), Group D ( combined ionizing radiation, treated with ionizing radiation from low dose to high dose : 50cGy first and 300cGy after 6h interval). The mRNA levels of HIF-1 and VEGF in each group were detected by real time polymerase chain reaction, while HPSE-1 expression was measured by ELISA. The microvessel density (MVD) and hypoxic cells were determined through immunohistochemical (IHC) staining of CD31 and HIF-1a.
Significant differences of HIF-1α mRNA level could be found among the 4 groups (F=74.164, P<0.001): Group C>Group A>Group D> Group B. The mRNA level of VEGF in Group C was significantly higher than in the other three groups (t=-5.267, P=0.000), while no significant difference was observed among Group A, B and D (t=1.528, 1.588; P=0.205, 0.222). In addition, the MVD was shown to be the highest in Group C (t=6.253, P=0.000), whereas the HPSE-1 level in Group A was lower than in Group B (t=14.066, P=0.000) and higher than in Group C (t=-21.919, P=0.000), and similar with Group D (t=-2.066, P=0.058). Through IHC staining of HIF-1a, the expression of hypoxic cells in Group A was (++), Group B was (+), Group C was (+++) and Group D was (+).
Ionizing radiation with lower- doses might improve tumor hypoxia through inhibiting the expression of HIF-1 and HPSE-1, whereas higher- doses worsen tumor hypoxic conditions by up-regulating HIF-1α, HPSE-1, VEGF and CD31 levels. A protocol of low-dose ionizing radiation followed by a high-dose irradiation might at least partly improve tumor hypoxia and enhance radiosensitivity.
我们旨在检测不同剂量电离辐射处理的裸鼠SKOV3异种移植瘤中HIF-1α、VEGF、HPSE-1和CD31的表达，试图探索缺氧和放射抗性的可能机制。
将携带SKOV3异种移植瘤的裸鼠随机分为4组：A组（对照组，未接受电离辐射）、B组（接受低剂量电离辐射：50cGy）、C组（接受高剂量电离辐射：300cGy）、D组（联合电离辐射，先接受低剂量电离辐射50cGy，间隔6小时后接受300cGy）。通过实时聚合酶链反应检测每组中HIF-1和VEGF的mRNA水平，同时用ELISA法检测HPSE-1的表达。通过CD31和HIF-1α的免疫组织化学（IHC）染色确定微血管密度（MVD）和缺氧细胞。
4组之间HIF-1α mRNA水平存在显著差异（F=74.164，P<0.001）：C组>A组>D组>B组。C组中VEGF的mRNA水平显著高于其他三组（t=-5.267，P=0.000），而A、B、D组之间未观察到显著差异（t=1.528，1.588；P=0.205，0.222）。此外，MVD显示在C组中最高（t=6.253，P=0.000），而A组中HPSE-1水平低于B组（t=14.066，P=0.000）且高于C组（t=-21.919，P=0.000），与D组相似（t=-2.066，P=0.058）。通过HIF-1α的IHC染色，A组缺氧细胞的表达为（++），B组为（+），C组为（+++），D组为（+）。
低剂量电离辐射可能通过抑制HIF-1和HPSE-1的表达改善肿瘤缺氧，而高剂量则通过上调HIF-1α、HPSE-1、VEGF和CD31水平恶化肿瘤缺氧状况。低剂量电离辐射后再进行高剂量照射的方案可能至少部分改善肿瘤缺氧并提高放射敏感性。
