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SH2 containing protein tyrosine phosphatase-2 (SHP2) is recognized as a druggable oncogenic phosphatase that is expressed in both tumor cells and immune cells. How tumor cell–autonomous SHP2 contributes to an immunosuppressive tumor microenvironment (TME) and therapeutic failure of immune checkpoint blockades in metastatic breast cancer (MBC) is not fully understood. Herein, we utilized systemic SHP2 inhibition and inducible genetic depletion of SHP2 to investigate immune reprogramming during SHP2 targeting. Pharmacologic inhibition of SHP2 sensitized MBC cells growing in the lung to α-programmed death ligand 1 (α-PD-L1) antibody treatment via relieving T-cell exhaustion induced by checkpoint blockade. Tumor cell–specific depletion of SHP2 similarly reduced pulmonary metastasis and also relieved exhaustion markers on CD8+ and CD4+ cells. Both systemic SHP2 inhibition and tumor cell–autonomous SHP2 depletion reduced tumor-infiltrated CD4+ T cells and M2-polarized tumor-associated macrophages. Analysis of TCGA datasets revealed that phosphorylation of SHP2 is important for immune-cell infiltration, T-cell activation and antigen presentation. To investigate this mechanistically, we conducted in vitro T-cell killing assays, which demonstrated that pretreatment of tumor cells with FGF2 and PDGF reduced the cytotoxicity of CD8+ T cells in a SHP2-dependent manner. Both growth factor receptor signaling and three-dimensional culture conditions transcriptionally induced PD-L1 via SHP2. Finally, SHP2 inhibition reduced MAPK signaling and enhanced STAT1 signaling, preventing growth factor–mediated suppression of MHC class I. Overall, our findings support the conclusion that tumor cell–autonomous SHP2 is a key signaling node utilized by MBC cells to engage immune-suppressive mechanisms in response to diverse signaling inputs from TME. Significance: Findings present inhibition of SHP2 as a therapeutic option to limit breast cancer metastasis by promoting antitumor immunity.

This is the code information for publicly available data analysis.

Corresponding representative dot plots for the quantification in figure 2D-F and additional myeloid composition analysis in the study of D2.A1 model.

T cell composition analysis in mice bearing SHP2 manipulated 4T1 metastases and representative dot plots for data shown in figure 4A.

SHP2 regulates MHC class I expression via the balance between MAPK and STAT1 signaling in human MBC cells.

Representative dot plots for data shown in figure 4B-C and additional exhaustion marker analysis of CD4+ T cells in mice bearing SHP2 manipulated 4T1 metastases.

Analyses of Tregs and macrophage scores in clinical datasets with respect to SHP2 phosphorylation.

Combination of SHP099 and α-PD-L1 delays D2.A1 pulmonary growth in vivo

The gating ancestry for the populations in the study of 4T1 model

Representative dot plots for data shown in figure 4D-F and additional exhaustion marker analysis of CD8+ T cells in mice bearing SHP2 manipulated 4T1 metastases.

Representative dot plots for data shown in figure 4G-H and additional myeloid composition analysis in mice bearing 4T1 metastases.

Corresponding representative dot plots for the quantification in figure 2A and additional T cell composition analysis in the study of D2.A1 model.

SH2 containing protein tyrosine phosphatase-2 (SHP2) is recognized as a druggable oncogenic phosphatase that is expressed in both tumor cells and immune cells. How tumor cell–autonomous SHP2 contributes to an immunosuppressive tumor microenvironment (TME) and therapeutic failure of immune checkpoint blockades in metastatic breast cancer (MBC) is not fully understood. Herein, we utilized systemic SHP2 inhibition and inducible genetic depletion of SHP2 to investigate immune reprogramming during SHP2 targeting. Pharmacologic inhibition of SHP2 sensitized MBC cells growing in the lung to α-programmed death ligand 1 (α-PD-L1) antibody treatment via relieving T-cell exhaustion induced by checkpoint blockade. Tumor cell–specific depletion of SHP2 similarly reduced pulmonary metastasis and also relieved exhaustion markers on CD8+ and CD4+ cells. Both systemic SHP2 inhibition and tumor cell–autonomous SHP2 depletion reduced tumor-infiltrated CD4+ T cells and M2-polarized tumor-associated macrophages. Analysis of TCGA datasets revealed that phosphorylation of SHP2 is important for immune-cell infiltration, T-cell activation and antigen presentation. To investigate this mechanistically, we conducted in vitro T-cell killing assays, which demonstrated that pretreatment of tumor cells with FGF2 and PDGF reduced the cytotoxicity of CD8+ T cells in a SHP2-dependent manner. Both growth factor receptor signaling and three-dimensional culture conditions transcriptionally induced PD-L1 via SHP2. Finally, SHP2 inhibition reduced MAPK signaling and enhanced STAT1 signaling, preventing growth factor–mediated suppression of MHC class I. Overall, our findings support the conclusion that tumor cell–autonomous SHP2 is a key signaling node utilized by MBC cells to engage immune-suppressive mechanisms in response to diverse signaling inputs from TME.Significance:Findings present inhibition of SHP2 as a therapeutic option to limit breast cancer metastasis by promoting antitumor immunity.

The gating ancestry for the populations in the study of D2.A1 model

Growth factors and 3D culture environment induce PD-L1 in MBC cells.

Corresponding representative dot plots for the quantification in figure 2B-C and additional T cell exhaustion marker analysis in the study of D2.A1 model.

These are supplementary tables to provide detailed information about the materials used in the study including cell, culture conditions, growth factors, inhibitors, and antibodies.

PD-L1 expression is induced by growth factor stimulation in the D2.A1 cells.

The production of adenosine by CD73 on cancer cells in the tumor microenvironment is a recognized immunosuppressive mechanism contributing to immune evasion in many solid tumors. While NK cells have been purported to overexpress CD73 under certain conditions, this phenomenon has remained elusive and unclear. We have found that while NK cells are able to upregulate expression of CD73 on their surface when exposed to CD73