DataSheet2_SHP2 inhibition improves celastrol-induced growth suppression of colorectal cancer.PDF

This study aimed to explore novel targets for celastrol sensitization in colorectal cancer (CRC) based on differentially regulated signals in response to high- or low-dose celastrol. Targeting signals were investigated using Western blotting or phosphorylated receptor tyrosine kinase (RTK) arrays. Corresponding inhibitors for the signals were individually combined with low-dose celastrol for the assessment of combined anti-CRC effects, based on proliferation, apoptosis, colony assays, and xenograft models. The potential mechanism for the combination of celastrol and SHP2 inhibition was further examined. Low-dose celastrol (<1 µM) did not effectively suppress AKT and ERK signals in CRC cells compared to high-dose celastrol (>1 µM). However, when combined with an AKT or ERK inhibitor, low-dose celastrol could cooperatively suppress CRC proliferation. Furthermore, failed AKT or ERK inhibition by low-dose celastrol may be due to reactivated RTK-SHP2 signaling with negative feedback. The combination of celastrol and the SHP2 inhibitor resulted in greatly reduced AKT and ERK signals, as well as greater inhibition of CRC growth than celastrol alone. Moreover, the mechanism underlying combination suppression was also involved in the activation of immune cell infiltration (mainly for CD8+ cells) in CRC tissues. Failure to inhibit RTK-SHP2-AKT/ERK signaling contributed to the lack of CRC growth suppression by low-dose celastrol. However, the combination of celastrol and the SHP2 inhibitor resulted in synergistic inhibition of CRC growth and provided a promising therapeutic target.

本研究旨在基于结直肠癌细胞（colorectal cancer, CRC）对高、低剂量雷公藤红素（celastrol）的差异调控信号，探索雷公藤红素在结直肠癌中的增敏新靶点。研究采用蛋白质印迹法（Western blotting）及磷酸化受体酪氨酸激酶（RTK）阵列，对相关信号通路进行分析。针对上述信号的特异性抑制剂分别与低剂量雷公藤红素联用，通过细胞增殖、细胞凋亡、集落形成实验及异种移植模型，评估二者联合的抗结直肠癌效应。随后进一步探究雷公藤红素与SHP2抑制剂联用的潜在作用机制。相较于高剂量雷公藤红素（>1 μM），低剂量雷公藤红素（<1 μM）无法有效抑制结直肠癌细胞中的AKT与ERK信号通路。但当低剂量雷公藤红素与AKT或ERK抑制剂联用时，可协同抑制结直肠癌细胞的增殖。此外，低剂量雷公藤红素无法有效抑制AKT与ERK信号通路，可能源于负反馈环路介导的RTK-SHP2信号通路重新激活。雷公藤红素与SHP2抑制剂联用，可显著下调AKT与ERK信号通路，且相较于单用雷公藤红素，能更有效地抑制结直肠癌的生长。此外，二者联合给药的抑癌机制还涉及激活结直肠癌组织中的免疫细胞浸润（主要为CD8+ T细胞）。低剂量雷公藤红素无法抑制结直肠癌生长的原因，在于其未能阻断RTK-SHP2-AKT/ERK信号通路。但雷公藤红素与SHP2抑制剂联用可产生协同抗结直肠癌生长的效应，为结直肠癌治疗提供了极具潜力的新靶点。