Oncodriver inhibition and CD4+ Th1 cytokines cooperate through Stat1 activation to induce tumor senescence and apoptosis in HER2+ and triple negative breast cancer: implications for combining immune and targeted therapies

// Cinthia Rosemblit 1, 2 , Jashodeep Datta 1 , Lea Lowenfeld 1 , Shuwen Xu 1 , Amrita Basu 2 , Krithika Kodumudi 2 , Doris Wiener 2 and Brian J. Czerniecki 1, 2 1 Harrison Department of Surgical Research, Department of Surgery, University Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA 2 Department of Clinical Science, H Lee Moffitt Cancer Center, Tampa, FL, USA Correspondence to: Brian J. Czerniecki, email: Brian.Czerniecki@moffitt.org Keywords: CD4 + T-helper immunity; HER2/neu; triple negative; breast cancer Received: June 20, 2016      Accepted: April 02, 2018      Published: May 01, 2018 ABSTRACT In patients with HER2-expressing breast cancer many develop resistance to HER2 targeted therapies. We show that high and intermediate HER2-expressing cancer cell lines are driven toward apoptosis and tumor senescence when treated with either CD4 + Th1 cells, or Th1 cytokines TNF-α and IFN-γ, in a dose dependent manner. Depletion of HER2 activity by either siRNA or trastuzumab and pertuzumab, and subsequent treatment with either anti-HER2 Th1 cells or TNF-α and IFN-γ resulted in synergistic increased tumor senescence and apoptosis in cells both sensitive and cells resistant to trastuzumab which was inhibited by neutralizing anti-TNF-α and IFN-γ. Th1 cytokines induced minimal senescence or apoptosis in triple negative breast cancer cells (TNBC); however, inhibition of EGFR in combination with Th1 cytokines sensitized those cells causing both senescence and apoptosis. TNF-α and IFN-γ led to increased Stat1 phosphorylation through serine and tyrosine sites and a compensatory reduction in Stat3 activation. Single agent IFN-γ enhanced Stat1 phosphorylation on tyrosine 701 and similar effects were observed in combination with TNF-α and EGFR inhibition. These results demonstrate Th1 cytokines and anti-oncodriver blockade cooperate in causing tumor senescence and apoptosis in TNBC and HER2-expressing breast cancer, suggesting these combinations could be explored as non-cross-reactive therapy preventing recurrence in breast cancer.