Department of Critical Care Medicine, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University and Collaborative Innovation Center of Biotherapy, No. 1, Ke Yuan 4th Road, Gao Peng Street, Chengdu, 610041, Sichuan, People's Republic of China.
Department of Intensive Care Unit of Gynecology and Obstetrics, West China Second University Hospital, Sichuan University, Chengdu, People's Republic of China.
Breast Cancer Res. 2020 Sep 29;22(1):103. doi: 10.1186/s13058-020-01346-y.
Sunitinib, a receptor tyrosine kinase (RTK) inhibitor that targets multiple receptors such as vascular endothelial growth factor receptors (VEGFRs), was approved for cancer treatment in 2006. However, it was unsuccessful in treating certain cancers, particularly metastatic breast cancer (MBC), and the mechanism underlying this "sunitinib resistance" remains unclear. Herein, we investigated whether the sunitinib-associated inferior survival benefit in MBC was due to sunitinib-induced endothelial cell (EC) injury or EC senescence.
4T1 murine breast cancer cells were used as the main breast tumor model for it produces a highly metastatic solid tumor that can spontaneously metastasize to the lung, which closely mimics highly metastatic human breast cancer. Senescence-associated β-galactosidase (SA-β-Gal, immunohistochemistry [IHC]-staining), P16, P53, and P57 (immunoblotting) were used as markers of cell senescence. A protein array containing 25 senescence-associated chemokines and the transwell chemotaxis assay were used to examine whether sunitinib increases inflammatory chemokine secretion which attracts tumor cells via chemokinesis. Flow cytometry and IHC were used to detect whether the sunitinib-induced senescent ECs recruit cancer-associated inflammatory myeloid cells. Finally, the spontaneous metastatic model was used to monitor whether sunitinib causes the formation of "pre-metastatic niche" which promotes MBC to metastasize to the lungs.
We demonstrated that sunitinib induced a senescence-like endothelial cell (EC) phenotype. Inflammatory chemokine secretion and VCAM1 expression were significantly increased in senescent ECs, resulting in tumor cell (TC) chemotaxis and TC/EC interactions. Meanwhile, EC senescence caused loosening of EC junctions, facilitating TC transmigration through the endothelial barrier. Sunitinib-induced senescent ECs also recruited cancer-associated myeloid cells to form a "pre-metastatic niche"-like microenvironment. Alterations at the molecular level and in the tissue environment ultimately led to an increase in distant metastasis.
Although sunitinib was designed to target the EC directly, the increase in tumor metastasis may ironically be due to sunitinib "correctly" playing its role. Our findings suggest that we should carefully weigh the pros and cons before using sunitinib and other antiangiogenic drugs that directly target the ECs.
舒尼替尼是一种受体酪氨酸激酶（RTK）抑制剂，可靶向多种受体，如血管内皮生长因子受体（VEGFRs），于 2006 年被批准用于癌症治疗。然而，它在治疗某些癌症方面并不成功，特别是转移性乳腺癌（MBC），其“舒尼替尼耐药”的机制尚不清楚。在此，我们研究了舒尼替尼在 MBC 中导致生存获益降低是否是由于舒尼替尼诱导的内皮细胞（EC）损伤或 EC 衰老。
使用 4T1 鼠乳腺癌细胞作为主要乳腺癌模型，因为它产生一种高度转移性的实体瘤，可自发转移到肺部，这与高度转移性的人类乳腺癌非常相似。衰老相关的β-半乳糖苷酶（SA-β-Gal，免疫组化[IHC]-染色）、P16、P53 和 P57（免疫印迹）被用作细胞衰老的标志物。使用含有 25 种衰老相关趋化因子的蛋白质阵列和 Transwell 趋化性测定来检查舒尼替尼是否增加炎症趋化因子的分泌，通过趋化作用吸引肿瘤细胞。使用流式细胞术和 IHC 来检测舒尼替尼诱导的衰老 EC 是否募集癌相关炎症性髓样细胞。最后，使用自发转移模型来监测舒尼替尼是否导致“前转移龛”的形成，从而促进 MBC 转移到肺部。
我们证明舒尼替尼诱导了类似衰老的内皮细胞（EC）表型。衰老的 EC 中炎症趋化因子的分泌和 VCAM1 的表达显著增加，导致肿瘤细胞（TC）趋化和 TC/EC 相互作用。同时，EC 衰老导致 EC 连接的松动，促进 TC 通过内皮屏障的迁移。舒尼替尼诱导的衰老 EC 还募集癌相关的髓样细胞形成类似于“前转移龛”的微环境。分子水平和组织环境的改变最终导致远处转移的增加。
尽管舒尼替尼旨在直接靶向 EC，但肿瘤转移的增加可能恰恰是由于舒尼替尼“正确”发挥了作用。我们的研究结果表明，在使用舒尼替尼和其他直接靶向 EC 的抗血管生成药物之前，我们应该仔细权衡利弊。
