Liu Feng, Wang Yutingzi, Cao Yang, Wu Zhiwei, Ma De, Cai Jun, Sha Jie, Chen Qing
Department of Proctology, Jingjiang People's Hospital, The Seventh Affiliated Hospital of Yangzhou University, Jingjiang, 214500, PR China.
Department of Pre-treatment, Jingjiang Chinese Medicine Hospital, Jingjiang, 214504, PR China.
Chem Biol Interact. 2023 Apr 1;374:110412. doi: 10.1016/j.cbi.2023.110412. Epub 2023 Feb 20.
Currently, resistance to oxaliplatin (OXA) has become an important obstacle to improving the clinical outcome of patients with colorectal cancer (CRC). Moreover, long non-coding RNAs (lncRNAs) have been documented in cancer chemoresistance, and our bioinformatic analysis suggested an involvement of lncRNA CCAT1 in CRC development. In this context, this study aimed to clarify the upstream and downstream mechanisms underpinning the effect of CCAT1 in the resistance of CRC to OXA. The expression of CCAT1 and the upstream B-MYB in the CRC samples was predicted by bioinformatics analysis and then verified using RT-qPCR in CRC cell lines. Accordingly, overexpression of B-MYB and CCAT1 was observed in CRC cells. SW480 cell line was used for the construction of OXA-resistant cell line (SW480R). Ectopic expression and knockdown experiments of B-MYB and CCAT1 were conducted in SW480R cells to delineate their roles in the malignant phenotypes and half-maximal (50%) inhibitory concentration (IC) of OXA. It was found that CCAT1 promoted the resistance of CRC cells to OXA. Mechanistically, B-MYB transcriptionally activated CCAT1, which recruited DNMT1 to inhibit SOCS3 expression through elevating the SOCS3 promoter methylation. By this mechanism, the resistance of CRC cells to OXA was enhanced. Meanwhile, these in vitro findings were reproduced in vivo on xenografts of SW480R cells in nude mice. To sum up, B-MYB might promote the chemoresistance of CRC cells to OXA via regulating the CCAT1/DNMT1/SOCS3 axis.
目前，对奥沙利铂（OXA）的耐药性已成为改善结直肠癌（CRC）患者临床结局的重要障碍。此外，长链非编码RNA（lncRNAs）已被证明与癌症化疗耐药性有关，我们的生物信息学分析表明lncRNA CCAT1参与了CRC的发展。在此背景下，本研究旨在阐明CCAT1在CRC对OXA耐药性中作用的上下游机制。通过生物信息学分析预测CRC样本中CCAT1和上游B-MYB的表达，然后在CRC细胞系中使用RT-qPCR进行验证。因此，在CRC细胞中观察到B-MYB和CCAT1的过表达。使用SW480细胞系构建奥沙利铂耐药细胞系（SW480R）。在SW480R细胞中进行B-MYB和CCAT1的异位表达和敲低实验，以阐明它们在恶性表型和奥沙利铂半数抑制浓度（IC50）中的作用。发现CCAT1促进CRC细胞对奥沙利铂的耐药性。机制上，B-MYB转录激活CCAT1，CCAT1招募DNMT1通过提高SOCS基因座甲基化来抑制SOCS3表达。通过这种机制，增强了CRC细胞对奥沙利铂的耐药性。同时，这些体外研究结果在裸鼠体内SW480R细胞异种移植模型中得到了验证。综上所述，B-MYB可能通过调节CCAT1/DNMT1/SOCS3轴促进CRC细胞对奥沙利铂的化疗耐药性。
