IMMUNEPOTENT CRP enhances cyclophosphamide-induced cytotoxicity through a caspase independent but ROS dependent mechanism in triple negative-breast cancer cells
Background: Breast cancer (BC) is one of the leading causes of cancer death worldwide. Cyclophosphamide (CYP) remains a mainstay in cancer therapy mainly in the triple negative breast cancer subtype (TNBC) in spite of harmful adverse effects and cell death-resistances. To face this, combination of chemotherapies and immunotherapies has been proposed. IMMUNEPOTENT CRP (ICRP) is an immunotherapy that has cytotoxic effects in several cancer cells without affecting peripheral blood mononuclear cells (PBMC) and CD3+ cells, beside improving clinical parameters of chemotherapy-treated patients. The aim of this study was to evaluate the mechanism of cytotoxicity induced by ICRP in combination with CYP (ICRP+CYP) in TNBC cells and their effect in healthy cells.
Methods: For this purpose, human and murine breast adenocarcinoma, MDA-MB-231 and 4T1 cells, beside PBMC were treated for 24 hours with ICRP, CYP or ICRP+CYP in different combination ratios for the assessment of cell death. Flow cytometry was used to determine biochemical characteristics of cell death.
Results: ANN/PI assays showed that ICRP+CYP induce cell cycle arrest in TNBC cells and potentiated cell death characterized by loss of mitochondrial membrane potential, reactive oxygen species (ROS) production and caspases activation. In addition, ICRP+CYP-cell death is ROS-dependent and caspases-independent in MDA-MB-231 and 4T1 cells. On the other hand, ICRP did not affect CYP-cytotoxicity in PBMC.
Conclusions: For all the above, we can propose that the combination of ICRP with CYP is an effective combination therapy, promoting their use even in tumoral cells with defects on proteins implicated in the apoptotic pathway
