Xu Jian, Zhang Rui, Zhao Jian
Cell Physiol Biochem. 2017;41(2):635-644. doi: 10.1159/000457938. Epub 2017 Feb 8.
BACKGROUND/AIMS: The novel long noncoding RNA (lncRNA) tumor suppressor candidate 7 (TUSC7) has been reported as a potential tumor suppressor, while the functional role of TUSC7 is still unknown in colorectal cancer (CRC). Here, we characterized TUSC7 expression profile in CRC patients and investigated its biological function and potential molecular mechanism.
RNA isolation, qRT-PCR, cell counter kit-8 assay, cell cycle assay, EdU assay, and western blot were performed. Statistical analyses were performed using SPSS 18.0 software and p value < 0.05 was considered as statistically significant.
In a cohort of CRC patients, we found TUSC7 was significantly downregulated in CRC tissues compared with adjacent non-tumor tissues (P < 0.01). Patients with high expression of TUSC7 had better survival than those with low expression of TUSC7 (HR = 0.342, 95% CI: 0.120-0.972, P = 0.044). Cell count kit 8 and EdU assays showed that ectopic expression of TUSC7 in HCT116 and SW480 cells significantly inhibited cell proliferation rate. After silence of TUSC7 with small interfering RNA, cell proliferation rate increased. Flow cytometry analyses revealed cycles were arrested at G1 phase after TUSC7 overexpression. We found there were 2 binding sites of miR-211-3p within the sequence of TUSC7 and TUSC7 expression level was negatively correlated with miR-211-3p. TUSC7 overexpression increased the expression level of CDK6, which is a downstream target of miR-211-3p, in both RNA and protein level. Furthermore, luciferase reporter assay indicated that TUSC7 could sponge miR-211-3p.
To summary, we demonstrated that TUSC7 is a potential tumor suppressor in CRC, and TUSC7 could inhibit CRC cell proliferation by completely sponging miR-211-3p.
背景/目的：新型长链非编码RNA（lncRNA）肿瘤抑制候选因子7（TUSC7）已被报道为一种潜在的肿瘤抑制因子，但其在结直肠癌（CRC）中的功能作用仍不清楚。在此，我们对CRC患者中TUSC7的表达谱进行了特征分析，并研究了其生物学功能和潜在的分子机制。
进行RNA分离、qRT-PCR、细胞计数试剂盒-8检测、细胞周期检测、EdU检测和蛋白质印迹分析。使用SPSS 18.0软件进行统计分析，p值<0.05被认为具有统计学意义。
在一组CRC患者中，我们发现与相邻非肿瘤组织相比，TUSC7在CRC组织中显著下调（P<0.01）。TUSC7高表达的患者比TUSC7低表达的患者具有更好的生存率（HR=0.342，95%CI：0.120-0.972，P=0.044）。细胞计数试剂盒8和EdU检测表明，TUSC7在HCT116和SW480细胞中的异位表达显著抑制细胞增殖率。用小干扰RNA沉默TUSC7后，细胞增殖率增加。流式细胞术分析显示，TUSC7过表达后细胞周期停滞在G1期。我们发现在TUSC7序列中有2个miR-211-3p的结合位点，且TUSC7表达水平与miR-211-3p呈负相关。TUSC7过表达在RNA和蛋白质水平上均增加了miR-211-3p的下游靶标CDK6的表达水平。此外，荧光素酶报告基因检测表明TUSC7可以吸附miR-211-3p。
总之，我们证明TUSC7是CRC中的一种潜在肿瘤抑制因子，并且TUSC7可以通过完全吸附miR-211-3p来抑制CRC细胞增殖。
