RNA结合基序蛋白24(RBM24)作为剪接调节因子,这对器官发育至关重要,在人类癌症中失调。这里,我们旨在揭示RBM24在结直肠肿瘤发生中的生物学功能。
移植瘤模型,利用Rbm24敲除和Apcmin/+小鼠模型。建立过表达或沉默RBM24的结直肠癌细胞。进行RNA免疫沉淀(RIP)测定以检测蛋白质-RNA关联。通过免疫组织化学测量基因表达,西方印迹,或定量PCR(qPCR)。
Rbm24基因敲除小鼠发生自发性结肠直肠腺瘤,磷酸酶和张力蛋白同源物(PTEN)表达较低。增殖标记Ki-67和pHH3和BrdU测定的免疫组织化学染色显示,与野生型小鼠相比,Rbm24敲除小鼠的肠增生。Apcmin/+小鼠结直肠腺瘤组织中RBM24的表达与邻近正常样本相比下调,且与PTEN表达呈正相关。体外,RBM24过表达抑制细胞增殖,迁移,CRC细胞的侵袭和对5-FU或顺铂的敏感性增加。机械上,RBM24通过直接与PTENmRNA的3'-UTR中的8101-8251位的富含GT的区域结合来维持PTENmRNA的稳定性,延长PTENmRNA的半衰期,从而增加PTEN表达。因此,RBM24低表达下调PTENmRNA,在CRC细胞中引起PI3K-Akt信号的激活。此外,RBM24在CRC组织中的表达低于癌旁正常样本。RBM24表达与PTEN表达呈正相关,与Ki-67表达呈负相关。具有高RBM24表达的CRC患者具有良好的预后。
合照,RBM24在结直肠肿瘤中的表达明显低于癌旁组织。Rbm24基因敲除小鼠发生自发性结直肠腺瘤。RBM24直接结合并稳定PTENmRNA,这可能会抑制CRC细胞的增殖,移民和入侵,从而抑制结直肠肿瘤发生。这些发现支持RBM24的肿瘤抑制作用。靶向RBM24对CRC的诊断和治疗具有很大的前景。
RNA-binding motif protein 24 (RBM24) functions as a splicing regulator, which is critical for organ development and is dysregulated in human cancers. Here, we aim to uncover the biological function of RBM24 in colorectal
tumourigenesis.
Xenograft tumour model, Rbm24 knockout and Apcmin/+ mouse models were utilised. Colorectal cancer cells overexpressing or silencing RBM24 were established. RNA immunoprecipitation (RIP) assay was conducted to detect protein-RNA associations. Gene expression was measured by immunohistochemistry, western blotting, or quantitative PCR (qPCR).
Rbm24-knockout mice developed spontaneous colorectal adenomas with lower expression of phosphatase and tensin homolog (PTEN). Immunohistochemical staining for the proliferation markers Ki-67 and pHH3 and BrdU assay showed intestinal hyperplasia in Rbm24-knockout mice compared to wild-type mice. RBM24 expression in colorectal adenoma tissues of Apcmin/+ mouse was downregulated compared with adjacent normal samples and was positively correlated with PTEN expression. In vitro, RBM24 overexpression suppressed cell proliferation, migration, invasion and increased sensitivity to 5-FU or cisplatin in CRC cells. Mechanistically, RBM24 maintained PTEN mRNA stability by directly binding to the GT-rich region at positions 8101-8251 in the 3\'-UTR of PTEN mRNA, prolonging the half-life of PTEN mRNA, thereby increasing PTEN expression. Hence, low expression of RBM24 downregulated PTEN mRNA, causing the activation of PI3K-Akt signalling in CRC cells. Furthermore, RBM24 expression in CRC tissues was lower than adjacent normal samples. RBM24 expression was positively correlated with PTEN expression and negatively correlated with Ki-67 level. CRC patients with high RBM24 expression had a favourable outcome.
Taken together, RBM24 expression is markedly lower in colorectal tumours than in para-carcinoma tissues. Rbm24-knockout mice develop spontaneous colorectal adenomas. RBM24 directly binds and stabilises PTEN mRNA, which could cause the suppression of CRC cell proliferation, migration and invasion, thereby repressing colorectal
tumourigenesis. These findings support the tumour-suppressive role of RBM24. Targeting RBM24 holds strong promise for the diagnosis and treatment of CRC.