State Key Laboratory of Cancer Biology, National Clinical Research Center for Digestive Diseases, Xijing Hospital of Digestive Diseases, Fourth Military Medical University, 127 West Changle Rd, Xi'an, 710032, Shaanxi, China.
Department of Gastroenterology, Tangdu Hospital, Fourth Military Medical University, Xi'an, 710038, Shaanxi, China.
Mol Cancer. 2022 Mar 12;21(1):74. doi: 10.1186/s12943-022-01555-3.
Epithelial-to-mesenchymal transition (EMT) is a process linked to metastasis and drug resistance with non-coding RNAs (ncRNAs) playing pivotal roles. We previously showed that miR-100 and miR-125b, embedded within the third intron of the ncRNA host gene MIR100HG, confer resistance to cetuximab, an anti-epidermal growth factor receptor (EGFR) monoclonal antibody, in colorectal cancer (CRC). However, whether the MIR100HG transcript itself has a role in cetuximab resistance or EMT is unknown.
The correlation between MIR100HG and EMT was analyzed by curating public CRC data repositories. The biological roles of MIR100HG in EMT, metastasis and cetuximab resistance in CRC were determined both in vitro and in vivo. The expression patterns of MIR100HG, hnRNPA2B1 and TCF7L2 in CRC specimens from patients who progressed on cetuximab and patients with metastatic disease were analyzed by RNAscope and immunohistochemical staining.
The expression of MIR100HG was strongly correlated with EMT markers and acted as a positive regulator of EMT. MIR100HG sustained cetuximab resistance and facilitated invasion and metastasis in CRC cells both in vitro and in vivo. hnRNPA2B1 was identified as a binding partner of MIR100HG. Mechanistically, MIR100HG maintained mRNA stability of TCF7L2, a major transcriptional coactivator of the Wnt/β-catenin signaling, by interacting with hnRNPA2B1. hnRNPA2B1 recognized the N6-methyladenosine (mA) site of TCF7L2 mRNA in the presence of MIR100HG. TCF7L2, in turn, activated MIR100HG transcription, forming a feed forward regulatory loop. The MIR100HG/hnRNPA2B1/TCF7L2 axis was augmented in specimens from CRC patients who either developed local or distant metastasis or had disease progression that was associated with cetuximab resistance.
MIR100HG and hnRNPA2B1 interact to control the transcriptional activity of Wnt signaling in CRC via regulation of TCF7L2 mRNA stability. Our findings identified MIR100HG as a potent EMT inducer in CRC that may contribute to cetuximab resistance and metastasis by activation of a MIR100HG/hnRNPA2B1/TCF7L2 feedback loop.
上皮-间充质转化（EMT）是与转移和耐药性相关的过程，非编码 RNA（ncRNA）起着关键作用。我们之前表明，miR-100 和 miR-125b 嵌入 ncRNA 宿主基因 MIR100HG 的第三个内含子中，使结直肠癌（CRC）对表皮生长因子受体（EGFR）单克隆抗体西妥昔单抗产生耐药性。然而，MIR100HG 转录本本身是否在西妥昔单抗耐药或 EMT 中发挥作用尚不清楚。
通过整理公共 CRC 数据存储库来分析 MIR100HG 与 EMT 之间的相关性。通过体外和体内实验确定 MIR100HG 在 CRC 中的 EMT、转移和西妥昔单抗耐药中的生物学作用。通过 RNAscope 和免疫组织化学染色分析在西妥昔单抗进展和转移性疾病患者的 CRC 标本中 MIR100HG、hnRNPA2B1 和 TCF7L2 的表达模式。
MIR100HG 的表达与 EMT 标志物强烈相关，并且作为 EMT 的正向调节剂发挥作用。MIR100HG 在体外和体内均维持 CRC 细胞对西妥昔单抗的耐药性并促进侵袭和转移。hnRNPA2B1 被鉴定为 MIR100HG 的结合伴侣。机制上，MIR100HG 通过与 hnRNPA2B1 相互作用维持 TCF7L2mRNA 的稳定性，TCF7L2 是 Wnt/β-连环蛋白信号的主要转录共激活因子。hnRNPA2B1 在存在 MIR100HG 的情况下识别 TCF7L2mRNA 的 N6-甲基腺苷（mA）位点。反过来，TCF7L2 激活 MIR100HG 转录，形成正反馈调节环。在 CRC 患者的标本中，MIR100HG/hnRNPA2B1/TCF7L2 轴增加，这些患者要么发生局部或远处转移，要么发生与西妥昔单抗耐药相关的疾病进展。
MIR100HG 和 hnRNPA2B1 通过调节 TCF7L2mRNA 的稳定性相互作用来控制 CRC 中 Wnt 信号的转录活性。我们的发现确定 MIR100HG 是 CRC 中一种有效的 EMT 诱导剂，通过激活 MIR100HG/hnRNPA2B1/TCF7L2 反馈环，可能导致西妥昔单抗耐药和转移。
