Elevated Production of Mitochondrial Reactive Oxygen Species via Hyperthermia Enhanced Cytotoxic Effect of Doxorubicin in Human Breast Cancer Cell Lines MDA-MB-453 and MCF-7

Abstract

Hyperthermia (HT) treatment is a noninvasive cancer therapy, often used with radiation therapy and chemotherapy. Compared with 37 °C, 42 °C is mild heat stress for cells and produces reactive oxygen species (ROS) from mitochondria. To involve subsequent intracellular accumulation of DOX, we have previously reported that the expression of ATP-binding cassette sub-family G member 2 (ABCG2), an exporter of doxorubicin (DOX), was suppressed by a larger amount of intracellular mitochondrial ROS. We then hypothesized that the additive effect of HT and chemotherapy would be induced by the downregulation of ABCG2 expression via intracellular ROS increase. We used human breast cancer cell lines, MCF-7 and MDA-MB-453, incubated at 37 °C or 42 °C for 1 h to clarify this hypothesis. Intracellular ROS production after HT was detected via electron spin resonance (ESR), and DOX cytotoxicity was calculated. Additionally, ABCG2 expression in whole cells was analyzed using Western blotting. We confirmed that the ESR signal peak with HT became higher than that without HT, indicating that the intracellular ROS level was increased by HT. ABCG2 expression was downregulated by HT, and cells were injured after DOX treatment. DOX cytotoxicity enhancement with HT was considered a result of ABCG2 expression downregulation via the increase of ROS production. HT increased intracellular ROS production and downregulated ABCG2 protein expression, leading to cell damage enhancement via DOX.

Co-Treatment of Caco-2 Cells with Doxorubicin and Gold Nanoparticles Produced from Cyclopia intermedia Extracts or Mangiferin Enhances Drug Effects

“…Interestingly, co-treatments with 1.56 µg/mL of DOX and HB-AuNPs (HB-AuNPs-DOX) or 1.56 µg/mL of DOX and MGF-AuNPs (MGF-AuNPs-DOX) also induced ROS production; the percentage of cells with high ROS levels was lower for the co-treatments when compared with the treatment with Low DOX alone. The increase in ROS production observed in Caco-2 cells treated with DOX was expected and is in agreement with previous studies [ 41 , 42 ]. The results of this study suggest that the biogenic NPs (HB-AuNPs and MGF-AuNPs) counter or reduce ROS production even in the presence of DOX.…”

Nanoparticle-Mediated Hyperthermia and Cytotoxicity Mechanisms in Cancer

“…This can increase blood perfusion, thus facilitating the intratumoral concentration of NPs [ 24 ]. It has been also suggested that modifications to cytoskeletal components may enhance intracellular drug delivery [ 25 ] and promote programmed cell death signaling through the induction of (i) alterations in the cytoskeleton-integrin network [ 26 ] or (ii) reactive oxygen species (ROS) production in mitochondria [ 27 ]. Moreover, nanoparticle-mediated HTT has been reported to increase the apoptosis and necrosis of tumor cells due to collagen fiber damage [ 28 ].…”

Hyperthermia Enhances Doxorubicin Therapeutic Efficacy against A375 and MNT-1 Melanoma Cells

“…A study with colorectal cancer has demonstrated that hyperthermia increases intracellular DOX concentrations [ 28 ]. In breast cancer, hyperthermia increased intracellular ROS production and downregulated ATP-binding cassette sub-family G member 2 (ABCG2) expression—an exporter of DOX—leading to cell damage enhancement via DOX [ 39 ]. In addition, Blasiak and colleagues demonstrated that DOX-resistant cancer cells exposed first to DOX and then to hyperthermia, needed double the amount of time to completely repair the DNA damaged by DOX, in comparison to their DOX-sensitive counterparts and to normal cells [ 40 ].…”