Triple Combination of Ascorbate, Menadione and the Inhibition of Peroxiredoxin-1 Produces Synergistic Cytotoxic Effects in Triple-Negative Breast Cancer Cells

Abstract

Triple-negative breast cancer (TNBC) is an aggressive form of mammary malignancy currently without satisfactory systemic treatment options. Agents generating reactive oxygen species (ROS), such as ascorbate (Asc) and menadione (Men), especially applied in combination, have been proposed as an alternative anticancer modality. However, their effectiveness can be hampered by the cytoprotective effects of elevated antioxidant enzymes (e.g., peroxiredoxins, PRDX) in cancer. In this study, PRDX1 mRNA and protein expression were assessed in TNBC tissues by analysis of the online RNA-seq datasets and immunohistochemical staining of tissue microarray, respectively. We demonstrated that PRDX1 mRNA expression was markedly elevated in primary TNBC tumors as compared to non-malignant controls, with PRDX1 protein staining intensity correlating with favorable survival parameters. Subsequently, PRDX1 functionality in TNBC cell lines or non-malignant mammary cells was targeted by genetic silencing or chemically by auranofin (AUR). The PRDX1-knockdown or AUR treatment resulted in inhibition of the growth of TNBC cells in vitro. These cytotoxic effects were further synergistically potentiated by the incubation with a combination of the prooxidant agents, Asc and Men. In conclusion, we report that the PRDX1-related antioxidant system is essential for maintaining redox homeostasis in TNBC cells and can be an attractive therapeutic target in combination with ROS-generating agents.

Antioxidants for the Treatment of Breast Cancer: Are We There Yet?

“…Be that as it may, the insufficient number of clinical studies and some experimental flaws not addressed by them makes it difficult to ascertain whether antioxidants may be potential therapeutic adjuvants, which is the main topic of this review. In line with other authors [ 22 , 25 , 259 , 260 ] we highlight common breaches in clinical trials that challenge a successful translation of antioxidants into cancer management, such as: route of administration; difficulty to achieve maintained therapeutic concentrations; low patient number; lack of previous preclinical assessment of a safe, effective and clinically relevant dose regimen for a given antioxidant (as monotherapy and combined with other therapeutics such as chemotherapy, radiotherapy or immunotherapy) in appropriate models of the breast cancer subtype under investigation (preferably patient-derived xenografts and/or organoids); non-standardized readouts (such as the impact on patient’s “redoxidomics”, gene and/or protein expression, post-translational protein modifications at tumor and antioxidant defense levels, or even on immune system that includes tumor-infiltrating lymphocytes or tumor-associated macrophages) and patient stratification (adjuvant or neoadjuvant therapy, “redoxidomic” status, breast tumor subtype, nutritional state, bodyweight or healthy habits followed by case subjects); lack of information about the impact on clinical outcome (overall, relapse-and metastasis-free survival); and low multidisciplinary teams.…”

“…Moreover, in TNBC, PRDX1 is crucial for maintaining the REDOX status and has a cytoprotective effect. Accordingly, PRDX1-knockdown resulted in the inhibition of cell growth in vitro and such effects were enhanced when it was combined with pro-oxidant agents like H 2 O 2 , glucose oxidase, sodium L-ascorbate or menadione [ 25 , 26 ].…”

Dual Inhibition of AKT and MEK Pathways Potentiates the Anti-Cancer Effect of Gefitinib in Triple-Negative Breast Cancer Cells

“…Additionally, inhibiting the mTORC1 pathway via the AKT inhibitor, MK2206, or blocking the regulatory-associated protein of mTOR (RPTOR) with small interfering RNA (siRNA) potentiated gefitinib toxicity in TNBC cells [ 33 ]. Recently, more efficacious treatments for TNBC have been suggested that use a triple combination of drugs targeting multiple pathways simultaneously, such as redox homeostasis, DNA synthesis, DNA damage, histone deacetylase, and multiple protein kinases [ 35 , 36 , 37 ]. A drug combination discovery involving 33 FDA-approved PKIs revealed that the triple combination of dasatinib, afatinib (BIBW-2992), and trametinib (GSK1120212) was anti-proliferative in TNBC cells by inhibiting SRC, HER2/EGFR, and MEK [ 37 , 38 , 39 , 40 ].…”

Cullin-5 neddylation-mediated NOXA degradation is enhanced by PRDX1 oligomers in colorectal cancer

“…The overexpression- and tumor-promoting effects of PRDX1 have been described in numerous types of human cancer 29 – 31 . Herein, our immunohistochemical staining results demonstrated that PRDX1 is also overexpressed in CRC tissues compared to ANTs (Fig.…”