Targeting stromal cell Syndecan-2 reduces breast tumour growth, metastasis and limits immune evasion

Tumour stromal cells support tumourigenesis. We report that Syndecan-2 (SDC2) is expressed on a nonepithelial, nonhaematopoietic, nonendothelial stromal cell population within breast cancer tissue. In vitro, syndecan-2 modulated TGF beta signalling (SMAD7, PAI-1), migration and immunosuppression of patient-derived tumour-associated stromal cells (TASCs). In an orthotopic immunocompromised breast cancer model, overexpression of syndecan-2 in TASCs significantly enhanced TGF beta signalling (SMAD7, PAI-1), tumour growth and metastasis, whereas reducing levels of SDC2 in TASCs attenuated TGF beta signalling (SMAD7, PAI-1, CXCR4), tumour growth and metastasis. To explore the potential for therapeutic application, a syndecan-2-peptide was generated that inhibited the migratory and immunosuppressive properties of TASCs in association with reduced expression of TGF beta-regulated immunosuppressive genes, such as CXCR4 and PD-L1. Moreover, using an orthotopic syngeneic breast cancer model, overexpression of syndecan-2-peptide in TASCs reduced tumour growth and immunosuppression within the TME. These data provide evidence that targeting stromal syndecan-2 within the TME inhibits tumour growth and metastasis due to decreased TGF beta signalling and increased immune control.

Automated summary

The study revealed that syndecan-2 expressed on a specific stromal cell population within tumors plays a crucial role in regulating tumor growth and metastasis through modulation of TGF beta signaling. Inhibiting the migratory and immunosuppressive properties of tumor-associated stromal cells (TASCs) can effectively suppress tumor growth and spread.