Tumor P70S6K hyperactivation is inversely associated with tumor-infiltrating lymphocytes in triple-negative breast cancer

PURPOSE: Triple-negative breast cancer (TNBC) is characterized by large heterogeneity and relative lack of available targeted therapies. To find therapeutic strategies for distinct patients with TNBC, several approaches have been used for TNBC clustering, including recently immune and phosphoproteomic patterns. Based on 70-kDa ribosomal protein S6 kinase (P70S6K)-TNBC clustering, the current study explores the immune profiling in TNBC tumors. METHODS: Stromal tumor-infiltrating lymphocytes (sTILs) were evaluated in human TNBC tumor samples. Furthermore, immunohistochemistry staining for CD8, CD4, Foxp3, and CD20 was performed in tissue microarrays (TMA) sections. RESULTS: Histological analysis showed decreased sTILs, CD20(+) cells, and CD8(+)/CD4(+) ratio in high phosphorylated P70S6K (p-P70S6K) tumors. Moreover, p-P70S6K score was directly correlated with CD4(+) and Foxp3(+) T cells, while it was inversely correlated with CD8(+)/CD4(+) and CD8(+)/Foxp3(+) ratios. CONCLUSION: sTIL infiltration and lymphocyte profiling vary in the context of hyperactivation of P70S6K in TNBC tumors.