Radiation Biology Research Center, Institute for Radiological Research, Chang Gung University/Chang Gung Memorial Hospital, Linkou 333, Taiwan.
Division of Gastroenterology, Cheng Hsin General Hospital, Taipei 112, Taiwan.
Int J Mol Sci. 2020 Oct 3;21(19):7315. doi: 10.3390/ijms21197315.
Signal transducer and activator of transcription 3 (STAT3), a transcriptional factor involved in tumorigenesis and cancer stemness formation, contributes to drug resistance in cancer therapies. STAT3 not only mediates gene transcription but also participates in microRNA suppression. This study identified a STAT3-downstream micro RNA (miRNA) involved in drug resistance against regorafenib in colorectal cancer stem-like tumorspheres. Small RNAseq was used to investigate differential microRNAs in colorectal cancer cell-derived tumorspheres and in a STAT3-knockdown strain. The miRNA-mediated genes were identified by comparing RNAseq data with gene targets predicted using TargetScan. Assays for detecting cell viability and apoptosis were used to validate findings. The formation of colorectal cancer stem-like tumorspheres was inhibited by BBI608, a STAT3 inhibitor, but not by regorafenib. Additional investigations for microRNA expression demonstrated an increase in 10 miRNAs and a decrease in 13 miRNAs in HT29-derived tumorspheres. A comparison of small RNAseq results between tumorspheres and HT29shSTAT3 cells revealed the presence of four STAT3-mediated miRNAs in HT29-derived tumorspheres: hsa-miR-215-5p, hsa-miR-4521, and hsa-miR-215-3p were upregulated, whereas miR-30a-5p was downregulated. Furthermore, hsa-miR-4521 was associated with poor overall survival probability, and miR-30a-5p was associated with better overall survival probability in patients with rectum cancer. Comparisons of RNAseq findings between HCT116- and HT29-derived tumorspheres revealed that HSPA5 were mediated by the STAT3-miR-30a-5p axis, which is overexpressed in colorectal tumorspheres associating to anti-apoptosis. In addition, the transfection of miR-30a-5p and inhibition of HSPA5 by HA15 significantly reduced cell viability and increased apoptosis in HT29 cells. In conclusion, a STAT3-miR-30a-5p-HSPA5 axis was observed against regorafenib-mediated apoptosis in colorectal cancer tumorspheres. The expression of miR-30a-5p was repressed by STAT3; in addition, HSPA5 was identified as the target gene of miR-30a-5p and contributed to both tumorsphere formation and anti-apoptosis.
信号转导子和转录激活子 3（STAT3）是一种参与肿瘤发生和癌症干细胞形成的转录因子，它有助于癌症治疗中的耐药性。STAT3 不仅介导基因转录，还参与 microRNA 的抑制。本研究鉴定了一种参与结直肠癌细胞球体中regorafenib 耐药的 STAT3 下游 microRNA（miRNA）。使用 small RNAseq 研究结直肠癌细胞球体和 STAT3 敲低株中的差异 microRNA。通过将 RNAseq 数据与使用 TargetScan 预测的基因靶标进行比较，鉴定 miRNA 介导的基因。用于检测细胞活力和细胞凋亡的测定用于验证发现。STAT3 抑制剂 BBI608 抑制结直肠癌细胞球体的形成，但不能抑制 regorafenib。microRNA 表达的进一步研究表明，HT29 来源的球体中 10 个 miRNA 增加，13 个 miRNA 减少。在 HT29shSTAT3 细胞和肿瘤球体之间的 small RNAseq 结果比较中，发现 HT29 来源的肿瘤球体中存在四种 STAT3 介导的 miRNA：hsa-miR-215-5p、hsa-miR-4521 和 hsa-miR-215-3p 上调，而 miR-30a-5p 下调。此外，hsa-miR-4521 与直肠癌患者的总体生存概率差相关，而 miR-30a-5p 与直肠癌患者的总体生存概率好相关。HCT116-和 HT29 来源的肿瘤球体之间的 RNAseq 结果比较表明，HSPA5 由 STAT3-miR-30a-5p 轴介导，该轴在结直肠肿瘤球体中过度表达，与抗细胞凋亡有关。此外，miR-30a-5p 的转染和 HA15 对 HSPA5 的抑制显著降低了 HT29 细胞的活力并增加了细胞凋亡。总之，在结直肠癌细胞球体中观察到针对 regorafenib 介导的细胞凋亡的 STAT3-miR-30a-5p-HSPA5 轴。miR-30a-5p 的表达受 STAT3 抑制；此外，HSPA5 被鉴定为 miR-30a-5p 的靶基因，并且有助于肿瘤球体的形成和抗细胞凋亡。
