Mesothelin-specific T cell cytotoxicity against triple negative breast cancer is enhanced by 40s ribosomal protein subunit 3-treated self-differentiated dendritic cells

Triple negative breast cancer (TNBC) lacks targeted treatment resulting in poor prognosis. Targeting overexpressing mesothelin (MSLN) using MSLN-specific T cells is an attractive treatment approach and the aim of the present study. The expression of MSLN in human TNBC paraffin sections was analyzed by immunohistochemistry. Lentiviral vector harbored granulocyte-macrophage colony stimulating factor (GM-CSF), interleukin-4 (IL-4) and MSLN cDNAs was constructed to generate self-differentiated myeloid-derived antigen-presenting-cells reactive against tumor expressing MSLN dendritic cell (MSLN-SmartDC) for MSLN-specific T cell activation. The results showed high MSLN in 32.8% of all breast cancer subtypes and 57% in TNBC. High MSLN was significantly associated with TNBC subtype and the absence of estrogen receptor, progesterone receptor and human epidermal growth factor receptor 2. MSLN-SmartDC exhibited comparable phenotype to DC generated by exogenous cytokine treatment and an addition of 40s ribosomal protein subunit 3 (RPS3), a toll-like receptor 4 ligand, enhanced DC maturation and function by upregulation of CD40, CD80 and CD83 expressions and IL-12p70 secretion. MSLN-specific CD8(+)CD69(+) IFN-γ(+) T cells were detected in T cells activated by both MSLN-SmartDC and RPS3-MSLN-SmartDC. MSLN-specific T cells activated by these DCs showed more specific killing capability against naturally expressed MSLN-HCC70 and artificially MSLN-overexpressing MDA-MB-231 compared with parental MDA-MB-231 in both two dimensional (2D)- and 3D-culture systems. In conclusion, the results demonstrated the efficacy of MSLN-SmartDC to promote MSLN-specific T cells response against TNBC and RPS3 can enhance the cytolytic activity of these T cells providing an alternative treatment approach for patients with TNBC.