摘要
Background:Colon cancer (CC) is a common malignant cancer. Recently, circFNDC3B was found to exert biological function in multiple cancers. However, it was unclear whether the potential protein encoded by circFNDC3B is involved in carcinogenesis of CC.
Methods:We used Sanger sequence and RNase R digestion assay to confirm the existence of circFNDC3B, and quantitative real-time PCR was used to evaluate the circRNA’s expression. Then fluorescence in situ hybridization (FISH) was performed to study location of circFNDC3B. The identification of protein encoded by circFNDC3B was performed using LC-MS/MS. The function of circFNDC3B-218aa on proliferation, invasion and migration were assessed by CCK8 assays, colony formation assays, transwell assays, wound-healing assays and animal experiments. RNA-sequencing and western blot were used to identify the gene regulated by circFNDC3B-218aa. Finally, glucose metabolism-related assays were performed to further investigate function of circFNDC3B-218aa.
Results:CircFNDC3B was localized mostly in the cytoplasm, and was decreased in CC cell lines and tissues. The patients with low circFNDC3B expression had a shorter OS (P = 0.0014) than patients with high expression. Moreover, circFNDC3B inhibited the proliferation, invasion and migration of CC cells. Next, we identified that circFNDC3B could encode a novel protein circFNDC3B-218aa. Furthermore, circFNDC3B-218aa, not circFNDC3B, inhibited the proliferation, invasion and migration of CC. Additionally, the in vivo experiments implied that up-regulated circFNDC3B-218aa exhibited an inhibitory effect on CC progression. By RNA-sequencing, western blot and glucose metabolism-related assays, we found that circFNDC3B-218aa inhibited the expression of Snail, and subsequently promoted the tumor-suppressive effect of FBP1 in CC.
Conclusions:The novel circFNDC3B-218aa may serve as a tumor suppressive factor and potential biomarker which may supply the potential therapeutic target for CC.
背景：结肠癌（CC）是一种常见的恶性肿瘤。近来发现circFNDC3B在多种肿瘤中发挥生物学功能。但是尚不清楚circFNDC3B编码的蛋白是否参与CC的肿瘤生成。
方法：我们使用Sanger测序和RNase R消化测定法来确认circFNDC3B的存在，并使用定量实时PCR评估circRNA的表达。通过荧光原位杂交（FISH）研究circFNDC3B的位置。使用LC-MS / MS对circFNDC3B编码的蛋白质进行鉴定。通过CCK8、克隆形成、transwell、划痕实验和动物实验评估了circFNDC3B-218aa对增殖、侵袭和迁移的影响。 RNA测序和western blot用于鉴定由circFNDC3B-218aa调控的基因。最后进行了葡萄糖代谢相关测定以进一步研究circFNDC3B-218aa的功能。
结果：circFNDC3B主要位于细胞质中，在CC细胞系和组织中减少。circFNDC3B表达低的患者的OS比高表达的患者短（P = 0.0014）。此外，circFNDC3B抑制CC细胞的增殖、侵袭和迁移。接下来，我们确定circFNDC3B可以编码一种新型蛋白质circFNDC3B-218aa。circFNDC3B-218aa而非circFNDC3B抑制了CC的增殖、侵袭和迁移。体内实验显示上调circFNDC3B-218aa对CC进展显示出抑制作用。通过RNA测序、western blot和葡萄糖代谢相关测定，我们发现circFNDC3B-218aa抑制Snail的表达，并促进FBP1在CC中的抑制肿瘤作用。
结论：circFNDC3B-218aa可作为肿瘤抑制因子和潜在的生物标志物，为CC提供潜在的治疗靶点。
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