Simone Brittany A, Ly David, Savage Jason E, Hewitt Stephen M, Dan Tu D, Ylaya Kris, Shankavaram Uma, Lim Meng, Jin Lianjin, Camphausen Kevin, Mitchell James B, Simone Nicole L
Department of Radiation Oncology, Kimmel Cancer Center, Jefferson Medical College of Thomas Jefferson University Hospital, Philadelphia, Pennsylvania.
Radiation Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland.
Int J Radiat Oncol Biol Phys. 2014 Sep 1;90(1):44-52. doi: 10.1016/j.ijrobp.2014.05.003. Epub 2014 Jun 28.
Although ionizing radiation is critical in treating cancer, radiation-induced fibrosis (RIF) can have a devastating impact on patients' quality of life. The molecular changes leading to radiation-induced fibrosis must be elucidated so that novel treatments can be designed.
To determine whether microRNAs (miRs) could be responsible for RIF, the fibrotic process was induced in the right hind legs of 9-week old CH3 mice by a single-fraction dose of irradiation to 35 Gy, and the left leg served as an unirradiated control. Fibrosis was quantified by measurements of leg length compared with control leg length. By 120 days after irradiation, the irradiated legs were 20% (P=.013) shorter on average than were the control legs.
Tissue analysis was done on muscle, skin, and subcutaneous tissue from irradiated and control legs. Fibrosis was noted on both gross and histologic examination by use of a pentachrome stain. Microarrays were performed at various times after irradiation, including 7 days, 14 days, 50 days, 90 days, and 120 days after irradiation. miR-15a, miR-21, miR-30a, and miR-34a were the miRs with the most significant alteration by array with miR-34a, proving most significant on confirmation by reverse transcriptase polymerase chain reaction, c-Met, a known effector of fibrosis and downstream molecule of miR-34a, was evaluated by use of 2 cell lines: HCT116 and 1522. The cell lines were exposed to various stressors to induce miR changes, specifically ionizing radiation. Additionally, in vitro transfections with pre-miRs and anti-miRs confirmed the relationship of miR-34a and c-Met.
Our data demonstrate an inverse relationship with miR-34a and c-Met; the upregulation of miR-34a in RIF causes inhibition of c-Met production. miRs may play a role in RIF; in particular, miR-34a should be investigated as a potential target to prevent or treat this devastating side effect of irradiation.
尽管电离辐射在癌症治疗中至关重要，但辐射诱导的纤维化（RIF）会对患者的生活质量产生毁灭性影响。必须阐明导致辐射诱导纤维化的分子变化，以便设计新的治疗方法。
为了确定微小RNA（miR）是否与RIF有关，对9周龄的CH3小鼠右后腿进行单次35 Gy剂量照射以诱导纤维化过程，左腿作为未照射对照。通过测量腿部长度并与对照腿长度比较来量化纤维化程度。照射后120天，照射腿平均比对照腿短20%（P = 0.013）。
对照射腿和对照腿的肌肉、皮肤及皮下组织进行组织分析。使用五色染色在大体和组织学检查中均发现纤维化。在照射后的不同时间进行微阵列分析，包括照射后7天、14天、50天、90天和120天。miR-15a、miR-21、miR-30a和miR-34a是微阵列分析中变化最显著的miR，其中miR-34a经逆转录聚合酶链反应证实最为显著。使用两种细胞系HCT116和1522评估了c-Met，它是已知的纤维化效应分子和miR-34a的下游分子。使细胞系暴露于各种应激源以诱导miR变化，特别是电离辐射。此外，用前体miR和抗miR进行体外转染证实了miR-34a与c-Met的关系。
我们的数据表明miR-34a与c-Met呈负相关；RIF中miR-34a的上调导致c-Met产生受到抑制。miR可能在RIF中起作用；特别是，miR-34a应作为预防或治疗这种毁灭性辐射副作用的潜在靶点进行研究。
