骨癌痛小鼠脊髓神经元miR-212与CREB磷酸化的关系

Relationship between spinal neuronal microRNA 212 and phosphorylation of CREB in a mouse model of bone cancer pain

目的探讨骨癌痛小鼠脊髓神经元微小RNA-212（miR-212）与cAMP反应元件结合蛋白（CREB）磷酸化的关系。方法SPF级雄性C3H／HeJ小鼠32只，4～6周龄，体重20～25g，采用随机数字表法将小鼠分为4组（n=8）：假手术组（S组）、骨癌痛组（BCP组）、骨癌痛＋鞘内注射阴性对照锁核酸组（BC组）和骨癌痛＋鞘内注射miR-212反义锁核酸组（BL组）。经股骨远端骨髓腔内注射含2×105个NCTC2472细胞的d-最小必需培养基20μl以制备骨癌痛模型。于接种后14d时，BL组和BC组分别鞘内注射miR-212反义锁核酸和阴性对照锁核酸12pmol／5l，1次／d，连续7d。S组及BCP组鞘内注射等容量无核酸酶水。于接种前1d、接种后4、7、10、14、21d时测定自发抬足次数（NSF）和机械缩足反应阈（MWT）。于接种后21d痛行为学测定结束后，取脊髓组织，采用Westernblot法测定脊髓磷酸化CREB（p-CREB）和CREB的表达水平。结果与S组相比，BCP组、BC组及BL组接种后7—21d时MWT降低，NSF增加，脊髓p-CREB表达上调（P〈O．05）。与BCP组相比，BL组接种后21d时MWT升高，NSF减少，脊髓p-CREB表达下调（P〈0．05），BC组上述指标差异无统计学意义（P〉0．05）。4组脊髓CREB表达水平比较差异无统计学意义（P〉0．05）。结论脊髓神经元miR-212可能通过促进CREB磷酸化参与小鼠骨癌痛的维持。

Objective To investigate the relationship between spinal neuronal microRNA 212 （miR-212） and phosphorylation of cAMP response element-binding protein （CREB） in a mouse model of bone cancer pain （BCP）. Methods Thirty-two male SPF C3H/HeJ mice, aged 4-6 weeks, weighing 20-25 g, were randomly divided into 4 groups （n = 8 each） using a random number table： sham operation group （group S）, BCP group, BCP ＋ intrathecal negative control locked nucleic acid （LNA） group （group BC） , and BCP ＋ intrathecal miR-212 antisense LNA group （group BL）. After the mice were anes- thetized with intraperitoneal pentobarbital sodium, 20 μl of a minimal essential medium containing NCTC 2472 cells 2×105 was injected directly into the medullary cavity of the distal femur. In BC and BL groups, negative control LNA and miR-212 antisense LNA 12 pmol/5 pd were intrathecally injected, respectively, once a day for 7 consecutive days, starting from day 14 after inoculation. In S and BCP groups, the equal volume of DNAse/RNAse-free water was given instead. The number of spontaneous flinches （NSF） and me- chanical paw withdrawal threshold （MWT） were measured on 1 day before inoculation and 4, 7, 10, 14 and 21 days after inoculation. The mice of each group were sacrificed after measurement of pain threshold on 21 days after inoculation, and the lumbar enlargement segments of the spinal cord were harvested to detect the expression of phosphorylated CREB （p-CREB） and CREB using Western blot. Results Compared with group S, the MWT was significantly decreased, and the NSF was increased on 7-21 days after inoculation, and the expression of p-CREB was up-regulated in BCP, BC and BL groups. Compared with group BCP, the MWT was significantly increased, and the NSF was decreased on 21 days after inoculation, and the expression of p-CREB was down-regulated in group BL, and no significant change was found in the parameters mentioned above in BC group. There was no significant difference in the expression of CREB between the four groups. Conclusion Spinal neuronal miR-212 is involved in the maintenance of BCP probably by pro- moting phosphorylation of CREB in mice.