Hao Ran, Zhang Lei, Si Yangming, Zhang Peng, Wang Yipeng, Li Bangchao, Hu Jie, Qi Yixin
Institutes of Health Research, Hebei Medical University, Shijiazhuang, Hebei, China.
School of Physical Science and Technology, Inner Mongolia University, Hohhot, Inner Mongolia, China.
Cancer Cell Int. 2023 Mar 25;23(1):54. doi: 10.1186/s12935-023-02895-w.
Metastasis is the leading cause of mortality in patients with breast cancer (BC). Studies demonstrate that circular RNAs (circRNAs) were involved in BC progression, while the molecular mechanisms remain largely unclear.
The microArray circRNA profiles were used to explore the differential expression circRNAs in BC and paracancerous normal tissues, and the quantitative reverse transcription-polymerase chain reaction was used to validate their expression level in clinical samples and cell lines. Nuclear/cytosolic fractionation and fluorescence in situ hybridization (FISH) assays were performed to examine circRRM2 (hsa_circ_0052582) subcellular location. The scratch wound healing and transwell assays were conducted to evaluate the impact of circRRM2 on BC cell migration and invasion. We predicted miRNAs that might bind with cricRRM2 and the downstream target genes using bioinformatics analysis and explored their expression levels and prognostic value in BC. FISH, RNA immunoprecipitation, Co-immunoprecipitation, Western blot, and rescue experiments were implemented to figure out circRRM2 function and underlying mechanisms in BC.
The present study revealed several aberrant circRNAs in BC tissues and observed that circRRM2 was upregulated in tumor tissues of 40 patients with BC. High circRRM2 was significantly associated with advanced N stage in patients with BC. Gain- and loss- of function experiments revealed that circRRM2 promoted the migration and invasion of cells and functioned as an oncogene in BC. Mechanism studies showed that circRRM2 competed with miR-31-5p/miR-27b-3p to upregulate the IGF2BP1 expression. Furthermore, IGF2BP1 upregulated the circRRM2 level via interacting with MYC, which functioned as the transcriptional factor of circRRM2. Thus, the positive feedback loop that was composed of circRRM2/IGF2BP1/MYC was identified.
This study confirms that upregulated circRRM2 functions an oncogenic role in BC metastasis. The positive feedback loop of circRRM2/IGF2BP1/MYC enforces the circRRM2 expression, which might offer a potential target for BC treatment.
转移是乳腺癌（BC）患者死亡的主要原因。研究表明，环状RNA（circRNA）参与了BC的进展，但其分子机制仍不清楚。
利用基因芯片circRNA谱探索BC组织和癌旁正常组织中差异表达的circRNA，并采用定量逆转录-聚合酶链反应验证其在临床样本和细胞系中的表达水平。进行细胞核/细胞质分级分离和荧光原位杂交（FISH）试验，以检测circRRM2（hsa_circ_0052582）的亚细胞定位。进行划痕伤口愈合试验和Transwell试验，以评估circRRM2对BC细胞迁移和侵袭的影响。我们使用生物信息学分析预测可能与circRRM2结合的miRNA及其下游靶基因，并探讨它们在BC中的表达水平和预后价值。实施FISH、RNA免疫沉淀、免疫共沉淀、蛋白质免疫印迹和拯救实验，以阐明circRRM2在BC中的功能和潜在机制。
本研究揭示了BC组织中几种异常的circRNA，并观察到40例BC患者肿瘤组织中circRRM2上调。高circRRM2与BC患者的晚期N分期显著相关。功能获得和缺失实验表明，circRRM2促进细胞迁移和侵袭，在BC中起癌基因作用。机制研究表明，circRRM2与miR-31-5p/miR-27b-3p竞争，上调IGF2BP1的表达。此外，IGF2BP1通过与作为circRRM2转录因子的MYC相互作用，上调circRRM2水平。因此，确定了由circRRM2/IGF2BP1/MYC组成的正反馈环。
本研究证实上调的circRRM2在BC转移中起致癌作用。circRRM2/IGF2BP1/MYC的正反馈环增强了circRRM2的表达，这可能为BC治疗提供一个潜在靶点。
