CD4 Th1 cytokines synergize with HER-2/HER-3 blockade to induce tumor senescence and apoptosis in both HER-2 sensitive and resistant breast cancer cells

ROSEMBLIT C ; CZERNIECKI BJ

Bellevue

Congreso; AACR Special Conference on Advances in Breast Cancer; 2015

American Association for Cancer Research (AACR)

Background: We have demonstrated there is a loss of anti-HER-2 Th1 response during tumorigenesis in HER-2pos breast cancer. Maintenance of this response is associated with complete response to neoadjuvant therapy and prolonged disease free survival. The CD4 Th1 or Th1 cytokines IFN-γ and TNF-α induce apoptosis and tumor senescence in HER-2pos breast cancer cells. In the current study we investigated whether combining Th1 cytokines with HER-2/HER-3 blockade would impact both HER-2 sensitive and resistant breast cancer cells.Results: SK-BR-3 breast cancer cells exposed to HER2 Class II peptide-primed CD4+ T-cells cells in a transwell culture system confirmed that the cytokines produced by the CD4+ T cells induced senescence and apoptosis of the HER-2pos cells as measured by SA--galactosidase (gal) staining, increased expression of p15INK4b and cleaved caspase 3 detected by western blot. CD4+ T-cells primed either with immature dendritic cells (DCs) or mature DCs plus irrelevant Class II (BRAF or survivin) peptides were not able to induce senescence, nor apoptosis. The senescence and apoptosis observed was dramatically augmented in HER-2pos cells exposed to HER2 Class II peptide-primed CD4+ T-cells in presence of trastuzumab and pertuzumab in the transwell. HER-2 resistant cells HCC-1419 and JIMT-1 treated with IFN-γ and TNF-α demonstrated a dose dependent increase in senescence and apoptosis suggesting HER-2 resistant cell lines are sensitive to Th1 cytokine effects. Both breast cancer cell lines tested express IFN-γ and TNF-α receptors as measured by western blot analysis. Although trastuzumab and pertuzumab had little effect on induction of senescence or apoptosis in the resistant cells, the combination of Th1 cytokines with trastuzumab and pertuzumab induced similar levels of senescence measured by SA--gal assay and p15INK4b as well as effectively induced cell death by apoptosis to levels similar to those seen in HER-2 sensitive cell lines. Conclusions: Our results establish a role for Th1 cytokines IFN-γ and TNF-α in inducing tumor senescence and apoptosis in both sensitive and resistant HER-2 expressing cells that is dramatically augmented by HER-2/HER-3 blockade. An effective CD4 Th1 response, combined with HER-2 and HER-3 blockade can significantly drive tumor senescence and apoptosis and should be readily explored as non-cross-reactive therapy to effectively eliminate residual cancer cells and prevent recurrence in HER-2pos breast cancer.