circ-0000284促肺鳞癌增殖和侵袭的机制研究

Circular RNA (circRNA), a close single strand circle RNA, was recently discovered as a special novel type of endogenous noncoding RNA. Emerging data shows that by acting as sponges of microRNA (miRNA), circRNAs are involved in the development of biosome and occurrence of human diseases. We have reported that angiogenin (ANG) promoted proliferation and invasion of lung squamous cell carcinoma (LSCC) via directly regulating HMGA2. We found ANG also upregulated the expression of circ-0000284. In vitro, pre-experiment results indicated that interfering the expression of circ-000284 attenuated the enhancement of ANG on proliferation and invasion of LSCC, and HMGA2 expression as well, which implied that circ-0000284 participated in proliferation and invasion of LSCC. We further found that circ-0000284 was the sponge of miR-486-5p, expression levels of which were significantly low in LSCC. In addition, results from pre-experiment showed that miR-486-5p not only inhibited proliferation and invasion of LSCC but also directly targeted HMGA2. We hypothesized that circ-0000284 regulated proliferation and invasion of LSCC via functioning as sponge of miR-486-5p to enhance the expression of HMGA2. Based on that, we focus on exploring the mechanisms of circ-0000284 enhancing proliferation and invasion of LSCC in this study. The results of this study might provide new sight into understanding the occurrence and development of LSCC.

最新研究发现环状RNA可通过作为miRNA的吸附海绵参与疾病的发生。我们前期已报导ANG可通过直接调控HMGA2促进肺鳞癌的增殖和侵袭。本课题组前期发现ANG可以上调环状RNA-0000284（circ-0000284）的表达，同时我们在体外预实验中发现干扰circ-0000284的表达可以削弱ANG对肺鳞癌增殖和侵袭的促进作用以及对HMGA2的上调作用，提示circ-0000284参与了肺鳞癌的增殖和侵袭。我们进一步发现circ-0000284是miR-486-5p的吸附海绵，且miR-486-5p在肺鳞癌中低表达。此外，我们还发现miR-486-5p不仅可以抑制肺鳞癌增殖和侵袭，还可以靶向抑制HMGA2。故我们提出本课题的猜想：circ-0000284通过作为miR-486-5p的吸附海绵，削弱miR-486-5p对HMGA2的抑制，上调HMGA2，实现对肺鳞癌增殖和侵袭的促进。

多项研究显示由HIPK3基因的转录产物反向剪接而成的环状RNA-0000284（circ-0000284）在多种肿瘤的进展中发挥了重要的作用，是一个功能强大的促癌因子，但目前暂无circ-0000284在肺鳞癌中作用的相关报导。. 在本课题的资助下，我们研究了circ-0000284在肺鳞癌中的基本表达状况、circ-0000284与肺鳞癌临床特征之间的相关性、circ-0000284在肺鳞癌发展中的作用以及发挥作用的相应机制。. 通过系列实验，我们发现circ-0000284的表达水平在肺鳞癌组织中显著上调，与肺鳞癌TNM分期中的T分期呈正相关。体外条件下，在肺鳞癌细胞系中过表达circ-0000284可以显著促进癌细胞的增殖及迁移能力，干扰circ-0000284的表达可以明显削弱肿瘤细胞的增殖及迁移能力。通过裸鼠成瘤后活体成像实验，我们发现circ-0000284可以显著促进肺鳞癌的成瘤能力及瘤体的生长。以上说明circ-0000284在肺鳞癌的发展中能发挥显著的促进作用，同时也提示circ-0000284可能与肺鳞癌的愈后相关。. 接下来，我们探索了circ-0000284促进肺鳞癌发展的机制，发现circ-0000284可以作为分子海绵吸附miR-541，而miR-541在体外条件下展示出了极强的抑癌作用，可以强烈抑制肺鳞癌细胞系SK-MES-1和H226的增殖、迁移及侵袭能力。进一步我们发现，miR-541实现上述作用的机制之一是通过靶向下调促癌基因HMGA2的表达。通过以上，我们阐明了circ-0000284促进肺鳞癌发展的分子机制即circ-0000284→miR-541→HMGA2。. 此外，在本课题的资助下，我们还探索了HMGA2与circRNA之间的相互作用在肺腺癌发展中的功能。通过一系列研究，我们发现在肺腺癌中存在一个由HMGA2和circASPH组成的正反馈回路，该回路中circASPH可以通过吸附miR-370上调HMGA2的表达，而HMGA2则通过结合ASPH的启动子区直接上调circASPH的表达水平，最后我们发现这个正反馈回路可以明显地促进肺腺癌的进展。同时，我与外单位的一个课题组合作，发现缺氧诱导条件下，在外泌体中富集的circSETDB1可以显著促进肺腺癌发展中上皮间质转化这一恶性过程。