State Key Laboratory for Functions and Applications of Medicinal Plants/College of Basic Medical Sciences, Guizhou Medical University, Guiyang, Guizhou, China.
The Key Laboratory of Chemistry for Natural Products of Guizhou Province and Chinese Academic of Sciences, Guiyang, Guizhou, China.
Cancer Gene Ther. 2022 Nov;29(11):1590-1599. doi: 10.1038/s41417-022-00471-4. Epub 2022 Apr 27.
RAS oncogenes are major drivers of diverse types of cancer. However, they are largely not druggable, and therefore targeting critical downstream pathways and dependencies is an attractive approach. We have isolated a tumorigenic cell line (FE1.2), which exhibits mesenchymal characteristics, after inoculating Ha-Ras-expressing retrovirus into mammary glands of rats, and subsequently isolated a non-aggressive revertant cell line (FC5). This revertant has lost the rat Ha-Ras driver and showed a more epithelial morphology, slower proliferation in culture, and reduced tumorigenicity in vivo. Re-expression of human Ha-RAS in these cells (FC5-RAS) reinduced mesenchymal morphology, higher proliferation rate, and tumorigenicity that was still significantly milder than parental FE1.2 cells. RNA-seq analysis of FC5-RAS vs FC5-Vector cells identified multiple genes whose expressions were regulated by Ha-RAS. This analysis also identified many genes including those controlling cell growth whose expression was altered by loss of HA-Ras in FC5 cells but remained unchanged upon reintroduction of Ha-RAS. These results suggest that targeting the Ha-Ras driver oncogene induces partial tumor regression, but it still denotes strong efficacy for cancer therapy. Among the RAS-responsive genes, we identified Twist1 as a critical mediator of epithelial-to-mesenchymal transition through the direct transcriptional regulation of vimentin. Mechanistically, we show that Twist1 is induced by the ETS gene, ETV4, downstream of Ha-RAS, and that inhibition of ETV4 suppressed the growth of breast cancer cells driven by the Ha-RAS pathway. Targeting the ETV4/Twist1/Vimentin axis may therefore offer a therapeutic modality for breast tumors driven by the Ha-RAS pathway.
RAS 癌基因是多种癌症的主要驱动因素。然而，它们在很大程度上不能被药物靶向，因此靶向关键的下游途径和依赖性是一种有吸引力的方法。我们在向大鼠乳腺接种表达 Ha-Ras 的逆转录病毒后，分离出了一个具有致瘤性的细胞系（FE1.2），该细胞系表现出间充质特征，随后分离出一个非侵袭性的回复细胞系（FC5）。这个回复细胞已经失去了大鼠 Ha-Ras 驱动基因，表现出更上皮样的形态，在培养中增殖速度较慢，体内致瘤性降低。在这些细胞中重新表达人 Ha-RAS（FC5-RAS）再次诱导出间充质形态，更高的增殖率，以及仍然明显低于亲本 FE1.2 细胞的致瘤性。FC5-RAS 与 FC5-Vector 细胞的 RNA-seq 分析鉴定出多个受 Ha-RAS 调控的基因。该分析还鉴定出许多基因，包括控制细胞生长的基因，这些基因在 FC5 细胞中失去 HA-Ras 时表达发生改变，但在重新引入 Ha-Ras 时保持不变。这些结果表明，靶向 Ha-Ras 驱动致癌基因会诱导部分肿瘤消退，但它仍然表示对癌症治疗具有很强的疗效。在 RAS 反应基因中，我们确定 Twist1 是通过对波形蛋白的直接转录调控来介导上皮间质转化的关键介质。在机制上，我们表明 Twist1 是由 Ha-Ras 下游的 ETS 基因 ETV4 诱导的，抑制 ETV4 可抑制 Ha-RAS 通路驱动的乳腺癌细胞的生长。因此，靶向 ETV4/Twist1/Vimentin 轴可能为 Ha-RAS 通路驱动的乳腺癌提供一种治疗模式。
