Wu Xiao-Yu, Chen Che, Yao Xue-Quan, Cao Qin-Hong, Xu Zhe, Li Wei-Su, Liu Fu-Kun, Li Gang
Department of Gastrointestinal Tumor Surgery, Affiliated Hospital of Nanjing University of Traditional Chinese Medicine, Nanjing, Jiangsu 210029, P.R. China.
Department of General Surgery, Jiangsu Cancer Hospital, Affiliated Cancer Hospital of Nanjing Medical University, Nanjing, Jiangsu 210009, P.R. China.
Mol Med Rep. 2014 Jul;10(1):486-90. doi: 10.3892/mmr.2014.2185. Epub 2014 Apr 24.
The present study aimed to examine the effects of recombinant human growth hormone (rhGH) on the sensitivity of a colorectal cancer cell line to radiotherapy, and to investigate its association with DNA damage and repair. Flow cytometry and immunofluorescence were employed to detect growth hormone receptor (GHR) expression in nine human colorectal cancer cell lines. A colony forming assay was performed to measure the colorectal cancer cell proliferation post‑radiotherapy, as an indicator of radiotherapy sensitivity. The comet assay results were interpreted as an indicator of radiotherapy‑induced DNA damage, and growth arrest and DNA damage 45 (GADD45) and apurinic/apyrimidinic endonuclease (APEN) protein expression were quantified with western blot analysis from the same cell lines. The results demonstrated that the colony‑forming efficiency (CFE) was significantly increased in HCT‑8 cells subject to radiotherapy and rhGH pretreatment compared with the cells treated with radiotherapy alone, in a dose‑dependent manner (0‑100 mg/l). This effect was enhanced under high doses of radiation (8 Gy; 52.1±2.9 vs. 21.0±2.7; P<0.001) and was ameliorated with GHR neutralizing antibody exposure. By contrast, rhGH pre‑incubation did not change the colony formation rate in GHR(‑) LOVO cells. rhGH intervention reduced the early HCT‑8 cell DNA damage (21.53±2.88 vs. 36.56±3.93; P=0.003) as well as the following plateau phase, compared with cells treated with radiotherapy alone (5.5±0.42 vs. 9.07±0.84; P=0.012). rhGH upregulated GADD45 and APEN protein expression, which is associated with cellular stress responses and DNA damage repair (P=0.007). The results suggest that rhGH is able to protect colorectal cancer cells from radiation through the interaction with GHR, which is associated with the promotion of DNA damage repair activity.
本研究旨在探讨重组人生长激素（rhGH）对大肠癌细胞系放疗敏感性的影响，并研究其与DNA损伤及修复的关系。采用流式细胞术和免疫荧光法检测9种人结肠癌细胞系中生长激素受体（GHR）的表达。进行集落形成试验以测量放疗后大肠癌细胞的增殖情况，作为放疗敏感性的指标。彗星试验结果被解释为放疗诱导的DNA损伤指标，并用蛋白质印迹分析法对同一细胞系中的生长停滞和DNA损伤45（GADD45）及脱嘌呤/脱嘧啶内切酶（APEN）蛋白表达进行定量分析。结果表明，与单纯接受放疗的细胞相比，接受放疗和rhGH预处理的HCT-8细胞的集落形成效率（CFE）显著增加，且呈剂量依赖性（0-100mg/L）。在高剂量辐射（8Gy）下这种效应增强（52.1±2.9对21.0±2.7；P<0.001），且在暴露于GHR中和抗体后减弱。相比之下，rhGH预孵育并未改变GHR（-）LOVO细胞的集落形成率。与单纯接受放疗的细胞相比，rhGH干预减少了HCT-8细胞早期的DNA损伤（21.53±2.88对36.56±3.93；P=0.003）以及随后的平台期（5.5±0.42对9.07±0.84；P=0.012）。rhGH上调了GADD45和APEN蛋白表达，这与细胞应激反应和DNA损伤修复相关（P=0.007）。结果表明，rhGH能够通过与GHR相互作用保护大肠癌细胞免受辐射，这与促进DNA损伤修复活性有关。
