Zhang Qi, Si Shuhui, Schoen Sue, Jin Xun-Bo, Chen Jindong, Wu Guan
Minimally Invasive Urology Center, Provincial Hospital Affiliated to Shandong University, Jinan, People's Republic of China; Department of Urology, University of Rochester Medical Center, Rochester, New York.
Department of Urology, University of Rochester Medical Center, Rochester, New York.
J Urol. 2014 Jun;191(6):1880-8. doi: 10.1016/j.juro.2014.01.001. Epub 2014 Jan 13.
Mutations in the FLCN gene are responsible for fibrofolliculoma, pulmonary and renal cysts, and renal cell carcinoma in patients with Birt-Hogg-Dubé syndrome. To explore therapeutic approaches to renal cell carcinoma in patients with Birt-Hogg-Dubé syndrome we investigated the anticancer effects of irradiation on folliculin deficient renal cancer cells.
Folliculin deficient (UOK257 and ACHN-5968) and folliculin expressing (UOK257-2 and ACHN-sc) cell lines were used in this study. Clonogenic assays were used to determine the radiosensitivity of folliculin deficient and expressing renal cell carcinoma cells. Apoptosis was detected in these cells by DAPI and TUNEL assays after irradiation. Monodansylcadaverine analysis, GFP-LC3 assay and Western blot were performed to monitor the autophagic process.
Folliculin deficient cells were more sensitive to irradiation than their folliculin expressing counterparts. The enhanced effects of irradiation on folliculin deficient cells were mediated by increased autophagy but not by apoptosis. An increased Beclin 1 protein level and an activated mitogen-activated protein kinase pathway were identified as the key regulators of increased autophagy in these folliculin deficient cells. Inhibiting autophagy with 3-methyladenine or beclin 1 siRNA obviously increased radioresistance in folliculin deficient cells. Moreover, irradiation combined with autophagic inducer rapamycin significantly increased autophagy and radiosensitivity in folliculin deficient renal cell carcinoma cells.
Findings suggest that folliculin deficient renal cell carcinoma cells are highly sensitive to irradiation due to increased autophagic cell death, unlike other types of renal cell carcinoma. Irradiation plus autophagy inducers, eg rapamycin, might be a potentially more effective therapeutic approach to folliculin deficient renal cell carcinoma.
在Birt-Hogg-Dubé综合征患者中，卵泡抑素（FLCN）基因突变可导致纤维毛囊瘤、肺囊肿和肾囊肿以及肾细胞癌。为了探索Birt-Hogg-Dubé综合征患者肾细胞癌的治疗方法，我们研究了辐射对卵泡抑素缺陷型肾癌细胞的抗癌作用。
本研究使用了卵泡抑素缺陷型（UOK257和ACHN-5968）和表达卵泡抑素的（UOK257-2和ACHN-sc）细胞系。采用克隆形成试验来确定卵泡抑素缺陷型和表达型肾癌细胞的放射敏感性。照射后，通过DAPI和TUNEL试验检测这些细胞中的凋亡情况。进行单丹磺酰尸胺分析、绿色荧光蛋白-微管相关蛋白1轻链3（GFP-LC3）试验和蛋白质免疫印迹法来监测自噬过程。
卵泡抑素缺陷型细胞比表达卵泡抑素的对应细胞对辐射更敏感。辐射对卵泡抑素缺陷型细胞的增强作用是由自噬增加介导的，而非凋亡。Beclin 1蛋白水平升高和丝裂原活化蛋白激酶途径激活被确定为这些卵泡抑素缺陷型细胞中自噬增加的关键调节因子。用3-甲基腺嘌呤或Beclin 1小干扰RNA抑制自噬明显增加了卵泡抑素缺陷型细胞中的放射抗性。此外，辐射联合自噬诱导剂雷帕霉素显著增加了卵泡抑素缺陷型肾癌细胞中的自噬和放射敏感性。
研究结果表明，与其他类型的肾细胞癌不同，卵泡抑素缺陷型肾癌细胞由于自噬性细胞死亡增加而对辐射高度敏感。辐射加自噬诱导剂，如雷帕霉素，可能是治疗卵泡抑素缺陷型肾细胞癌的一种潜在更有效的治疗方法。
