Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, Jiangsu Province, China.
Department of General Surgery, The Affiliated Huaian No.1 People's Hospital of Nanjing Medical University, Huaian, 223300, Jiangsu Province, China.
J Exp Clin Cancer Res. 2021 Jan 5;40(1):6. doi: 10.1186/s13046-020-01791-9.
Gastric cancer (GC) is one of the most common malignant tumors worldwide. Currently, the overall survival rate of GC is still unsatisfactory despite progress in diagnosis and treatment. Therefore, studying the molecular mechanisms involved in GC is vital for diagnosis and treatment. CircRNAs, a type of noncoding RNA, have been proven to act as miRNA sponges that can widely regulate various cancers. By this mechanism, circRNA can regulate tumors at the genetic level by releasing miRNA from inhibiting its target genes. The WNT2/β-Catenin regulatory pathway is one of the canonical signaling pathways in tumors. It can not only promote the development of tumors but also provide energy for tumor growth through cell metabolism (such as glutamine metabolism).
Through RNA sequencing, we found that hsa_circ_0008259 (circLMO7) was highly expressed in GC tissues. After verifying the circular characteristics of circLMO7, we determined the downstream miRNA (miR-30a-3p) of circLMO7 by RNA pull-down and luciferase reporter assays. We verified the effect of circLMO7 and miR-30a-3p on GC cells through a series of functional experiments, including colony formation, 5-ethynyl-2'-deoxyuridine and Transwell assays. Through Western blot and immunofluorescence analyses, we found that WNT2 was the downstream target gene of miR-30a-3p and further confirmed that the circLMO7-miR-30a-3p-WNT2 axis could promote the development of GC. In addition, measurement of related metabolites confirmed that this axis could also provide energy for the growth of GC cells through glutamine metabolism. We found that circLMO7 could promote the growth and metastasis of GC in vivo by the establishment of nude mouse models. Finally, we also demonstrated that HNRNPL could bind to the flanking introns of the circLMO7 exons to promote circLMO7 cyclization.
CircLMO7 acted as a miR-30a-3p sponge affecting the WNT2/β-Catenin pathway to promote the proliferation, migration and invasion of GC cells. Moreover, animal results also showed that circLMO7 could promote GC growth and metastasis in vivo. CircLMO7 could also affect the glutamine metabolism of GC cells through the WNT2/β-Catenin pathway to promote its malignant biological function. In addition, we proved that HNRNPL could promote the self-cyclization of circLMO7.
CircLMO7 promotes the development of GC by releasing the inhibitory effect of miR-30a-3p on its target gene WNT2.
胃癌（GC）是全球最常见的恶性肿瘤之一。尽管在诊断和治疗方面取得了进展，但 GC 的总体生存率仍然不尽如人意。因此，研究 GC 涉及的分子机制对于诊断和治疗至关重要。CircRNAs 是一种非编码 RNA，已被证明可以作为 miRNA 的海绵，广泛调节各种癌症。通过这种机制，circRNA 可以通过释放 miRNA 来抑制其靶基因，从遗传水平上调节肿瘤。WNT2/β-连环蛋白调控途径是肿瘤中经典的信号通路之一。它不仅可以促进肿瘤的发展，还可以通过细胞代谢（如谷氨酰胺代谢）为肿瘤生长提供能量。
通过 RNA 测序，我们发现 hsa_circ_0008259（circLMO7）在 GC 组织中高表达。在验证了 circLMO7 的环状特征后，我们通过 RNA 下拉和荧光素酶报告基因实验确定了 circLMO7 的下游 miRNA（miR-30a-3p）。我们通过一系列功能实验，包括集落形成、5-乙炔基-2'-脱氧尿苷和 Transwell 实验，验证了 circLMO7 和 miR-30a-3p 对 GC 细胞的影响。通过 Western blot 和免疫荧光分析，我们发现 WNT2 是 miR-30a-3p 的下游靶基因，并进一步证实 circLMO7-miR-30a-3p-WNT2 轴可以促进 GC 的发展。此外，相关代谢物的测量证实，该轴还可以通过谷氨酰胺代谢为 GC 细胞的生长提供能量。我们通过建立裸鼠模型发现，circLMO7 可以促进体内 GC 的生长和转移。最后，我们还证明 HNRNPL 可以与 circLMO7 外显子的侧翼内含子结合，促进 circLMO7 的环化。
circLMO7 作为 miR-30a-3p 的海绵，影响 WNT2/β-连环蛋白通路，促进 GC 细胞的增殖、迁移和侵袭。此外，动物实验结果还表明，circLMO7 可以促进体内 GC 的生长和转移。circLMO7 还可以通过 WNT2/β-连环蛋白通路影响 GC 细胞的谷氨酰胺代谢，促进其恶性生物学功能。此外，我们证明 HNRNPL 可以促进 circLMO7 的自我环化。
circLMO7 通过释放 miR-30a-3p 对其靶基因 WNT2 的抑制作用，促进 GC 的发展。
