Sunitinib facilitates metastatic breast cancer spreading by inducing endothelial cell senescence

Abstract

Background 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. Methods 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. Results 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. Conclusion 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.

Hallmarks of Cancer: New Dimensions

“…While less well established, it seems likely that other abundant stromal cells populating particular tumor microenvironments will prove to undergo senescence, and thereby modulate cancer hallmarks and consequent tumor phenotypes. For example, therapy-induced senescent tumor endothelial cells can enhance proliferation, invasion, and metastasis in breast cancer models (124,125).…”

Pancreatic Cancer and Cellular Senescence: Tumor Microenvironment under the Spotlight

“…In particular, the production of CXCL11 from endothelial cells was shown to promote the cell proliferation, migration, and invasion of breast cancer cells in vitro [ 174 ]. Similarly, Wang et al have shown that sunitinib-induced senescence stimulates endothelial cells to secrete pro-inflammatory cytokines, thus promoting cancer metastasis and invasion [ 175 ]. In contrast with those studies, Ruscetti et al have demonstrated that the induction of senescence in PDAC cells, through the use of a combination of palbociclib and trametinib, induced vascular remodeling within the tumor, increasing its sensitivity to cytotoxic drugs and promoting T-cell infiltration [ 176 ].…”

A New Antitumor Direction: Tumor-Specific Endothelial Cells

“…Several studies revealed sunitinib, a TKI, not only targets VEGFR (32) but also inhibits PDGFR (33) and FGFR (34).Sunitinib has been used to treat a variety of cancers. Similarly, studies have reported that sunitinib treatment alone can cause ECs senescence, loose ECs connections, and promote tumor cell migration through the endothelial barrier (35). Based on the above research reports, treatment with one antitumor angiogenesis drug alone have great limit effects on cancer therapy (Figure 1).…”