naphthoquinones and Triple-Negative-Breast-Neoplasms

Although chemoimmunotherapy has achieved considerable success in cancer treatment in recent years, the cure for triple-negative breast cancer (TNBC) remains elusive. The unsatisfied outcomes are likely attributed to deficient tumor immunogenicity, a strong immunosuppressive tumor microenvironment (ITM) and tumor metastasis. To address this issue, we constructed an effective codelivery system, combined with tumor growth factor β (TGF-β) small interference RNA (siTGF-β) and shikonin (SK), to achieve successful chemoimmunotherapy of TNBC. The SK/siTGF-β NPs (approximately 110 nm) exhibited a uniform structure and good stability. Conjugated FA presented enhanced cellular uptake in 4T1 cells, and siTGF-β escaped from lysosomes because of the "proton sponge" effect of PEI. Furthermore, SK actually induced satisfactory immunogenic cell death (ICD) and the resulting dendritic cell (DC) maturation facilitated a distinctly enhanced cytotoxic T lymphocyte (CTL) response, generating a positive effect on tumor suppression. Simultaneously, the successful silencing of TGF-β alleviated the TGF-β-mediated ITM and inhibited the epithelial-to-mesenchymal transition (EMT), contributing to the infiltration of CTLs, suppression of regulatory T lymphocyte (Treg) proliferation and lung metastasis inhibition. Thus, the SK/siTGF-β NPs demonstrated the strongest therapeutic effect with delayed tumor growth (TIR = 88.5%) and lung metastasis restraint (77.3%). More importantly, tumor rechallenge assay suggested that the codelivery system produced a long-term immunological memory response to prevent tumor recurrence. Based on boosting the immune response and combating the ITM, SK/siTGF-β NPs would be a potential approach for TNBC therapy.

Topics: Cell Line, Tumor; Humans; Immunotherapy; Naphthoquinones; Triple Negative Breast Neoplasms; Tumor Microenvironment

The mitochondria represent a potential target for the treatment of triple-negative breast cancer (TNBC) and shikonin (SK) has shown remarkable therapeutic effects on TNBC. Herein, it is found that SK possesses potent inhibitory effects on mitochondrial biogenesis via targeting polymerase gamma (POLG). However, its application is restricted by its poor aqueous solubility and stability, and therefore, a biomimetic micelle to aid with tumor lesion accumulation and mitochondria-targeted delivery of SK is designed. A folic acid (FA) conjugated polyethylene glycol derivative (FA-PEG-FA) is inserted onto the external membranes of red blood cells (FP-RBCm) to prepare a "right-side-out" RBCm-camouflaged cationic micelle (ThTM/SK@FP-RBCm). Both FP-RBCm coating and a triphenylphosphine (TPP) moiety on the periphery of micelles contribute to tumor lesion distribution, receptor-mediated cellular uptake, and electrostatic attraction-dependent mitochondrial targeting, thereby maximizing inhibitory effects on mitochondrial biosynthesis in TNBC cells. Intravenous administration of ThTM/SK@FP-RBCm leads to profound inhibition of tumor growth and lung metastasis in a TNBC mouse model with no obvious toxicity. This work highlights the mitochondria-targeted delivery of SK using a "right-side-out" membrane-camouflaged micelle for the inhibition of mitochondrial biogenesis and enhanced therapeutic effects on TNBC.

Topics: Animals; Cell Line, Tumor; Folic Acid; Humans; Mice; Micelles; Naphthoquinones; Organelle Biogenesis; Polyethylene Glycols; Triple Negative Breast Neoplasms

Triple-negative breast cancer (TNBC) is heterogeneous disease with a poor prognosis. It is therefore important to explore novel therapeutic agents to improve the clinical efficacy for TNBC. The inosine 5'-monophosphate dehydrogenase 2 (IMPDH2) is a rate-limiting enzyme in the de novo synthesis of guanine nucleotides. It is always overexpressed in many types of tumors, including TNBC and regarded as a potential target for cancer therapy. Through screening a library of natural products, we identified shikonin, a natural bioactive component of Lithospermum erythrorhizon, is a novel and selective IMPDH2 inhibitor. Enzymatic analysis using Lineweaver-Burk plot indicates that shikonin is a competitive inhibitor of IMPDH2. The interaction between shikonin and IMDPH2 was further investigated by thermal shift assay, fluorescence quenching, and molecular docking simulation. Shikonin treatment effectively inhibits the growth of human TNBC cell line MDA-MB-231, and murine TNBC cell line, 4T1 in a dose-dependent manner, which is impaired by exogenous supplementation of guanosine, a salvage pathway of purine nucleotides. Most importantly, IMPDH2 knockdown significantly reduced cell proliferation and conferred resistance to shikonin in TNBC. Collectively, our findings showed the natural product shikonin as a selective inhibitor of IMPDH2 with anti-TNBC activity, impelling its further study in clinical trials.

Topics: Animals; Cell Line, Tumor; Cell Proliferation; Enzyme Inhibitors; Female; Gene Knockdown Techniques; Humans; IMP Dehydrogenase; Lithospermum; Mice; Molecular Docking Simulation; Naphthoquinones; Triple Negative Breast Neoplasms

The persistent activation of aerobic glycolysis in cancer cells results in accumulation of lactate and other metabolic intermediates that contribute to tumorigenesis. Increased glycolysis is frequently dysregulated in triple-negative breast cancer (TNBC), which promotes tumor growth and immune escape. This study was conducted to investigate the effect of 2-methoxy-1, 4-naphthoquinone (MNQ), compound extracted from Impatiens balsamina on glycolytic activities in human breast adenocarcinoma, MDA-MB-231 cells.. Initially, MTT proliferation assay was used to test the cell viability with various doses of MNQ (5-100 µM). As the half maximal inhibitory concentration (IC50) was obtained, glucose uptake and lactate assays of the cells were tested with IC50 dose of MNQ. The treated cells were also subjected to gene and protein analysis of glycolysis-related molecules (GLUT1 and Akt).. The results showed that MNQ decreased the percentage of MDA-MB-231 cell viability in a dose-dependent manner with the IC50 value of 29 µM. The percentage of glucose uptake into the cells and lactate production decreased significantly after treatment with MNQ as compared to untreated cells. Remarkably, the expressions of GLUT1 and Akt molecules decreased in MNQ-treated cells, suggesting that the inhibition of glycolysis by MNQ is GLUT1-dependent and possibly mediated by the Akt signaling pathway.. Our findings indicate the ability of MNQ to inhibit the glycolytic activities as well as glycolysis-related molecules in MDA-MB-231 cells, suggesting the potential of MNQ to be further developed as an effective anticancer agent against TNBC cells.

Topics: Antineoplastic Agents; Cell Survival; Female; Glucose; Glycolysis; Humans; Lactic Acid; Naphthoquinones; Triple Negative Breast Neoplasms; Tumor Cells, Cultured

Rubia yunnanensis Diels is a traditional Chinese medicine that has diverse pharmacological activities, including antituberculosis, antirheumatism and anticancers. Rubioncolin C (RC), a natural naphthohydroquinone dimer isolated from the roots and rhizomes of R. yunnanensis Diels, has shown potent antitumor activity. However, the antitumor activity and its potential mechanism of RC in triple-negative breast cancer (TNBC) cell lines remained unclear.. This study was aim to investigate the anti-proliferation and anti-metastasis activity as well as the potential mechanism of RC on triple-negative breast cancer cells in vitro and in vivo.. The sulforhodamine B assay, colony formation assay and cell cycle analysis were used to determine the anti-proliferative activity of RC on TNBC. The anti-metastatic activity in vitro of RC was detected through the scratch wound assay, cell migration and invasion assays and gelatin zymography. The flow cytometry, JC-1, GFP-LC3B plasmid transfection, MDC, Lysotracker red and Carboxy-H. In the present study, RC suppressed the proliferation of TNBC cells in a time- and dose-dependent manner via regulating cell cycle. Further experiments showed that RC inhibited the migration and invasion of TNBC cells by downregulating MMPs and inhibiting EMT. Moreover, we demonstrated that RC induced obviously apoptotic and autophagic cell death, activated MAPK signaling pathway and inhibited mTOR/Akt/p70S6K and NF-κB signaling pathways. Furthermore, the excessive ROS was produced after treatment with RC. The antioxygen NAC and GSH could rescue the cell viability and reestablish the ability of cell metastasis, and inhibit the RC-induced apoptosis and autophagy. In a mice lung metastasis model of breast cancer, RC inhibited lung metastasis, and induced autophagy and apoptosis.. These findings clarified the antitumor mechanism of RC on TNBC cell lines and suggested that RC is a key active ingredient for the cancer treatment of R. yunnanensis, which would help RC develop as a new potential chemotherapeutic agent for TNBC treatment.

Topics: Animals; Antineoplastic Agents, Phytogenic; Autophagy; Cell Line, Tumor; Cell Movement; Cell Proliferation; Cell Survival; Dose-Response Relationship, Drug; Female; Humans; Mice; Mice, Inbred BALB C; Naphthoquinones; Neoplasm Invasiveness; Neoplasm Metastasis; Reactive Oxygen Species; Rubia; Time Factors; Triple Negative Breast Neoplasms

Compared with other breast cancer subtypes, triple-negative breast cancer (TNBC) is associated with relatively poor outcomes due to its metastatic propensity, frequent failure to respond to chemotherapy, and lack of alternative, targeted treatment options, despite decades of major research efforts. Our studies sought to identify promising targeted therapeutic candidates for TNBC through in vitro screening of 1,363 drugs in patient-derived xenograft (PDX) models. Using this approach, we generated a dataset that can be used to assess and compare responses of various breast cancer PDXs to many different drugs. Through a series of further drug screening assays and two-drug combination testing, we identified that the combination of afatinib (epidermal growth factor receptor (EGFR) inhibitor) and YM155 (inhibitor of baculoviral inhibitor of apoptosis repeat-containing 5 (BIRC5; survivin) expression) is synergistically cytotoxic across multiple models of basal-like TNBC and reduces PDX mammary tumor growth in vivo. We found that YM155 reduces EGFR expression in TNBC cells, shedding light on its potential mechanism of synergism with afatinib. Both EGFR and BIRC5 are highly expressed in basal-like PDXs, cell lines, and patients, and high expression of both genes reduces metastasis-free survival, suggesting that co-targeting of these proteins holds promise for potential clinical success in TNBC.

Topics: Afatinib; Animals; Antineoplastic Combined Chemotherapy Protocols; Carboplatin; Cell Line, Tumor; Cell Survival; Dose-Response Relationship, Drug; Drug Screening Assays, Antitumor; Drug Synergism; ErbB Receptors; Female; Humans; Imidazoles; Mice; Mice, Inbred NOD; Mice, SCID; Naphthoquinones; Oligopeptides; Survivin; Triple Negative Breast Neoplasms; Xenograft Model Antitumor Assays

Radioresistant cells cause recurrence in patients with breast cancer after they undergo radiation therapy. The molecular mechanisms by which cancer cells obtain radioresistance should be understood to develop radiation-sensitizing agents. Results showed that the protein expression and activity of NAD(P)H:quinone oxidoreductase 1 (NQO1) were upregulated in radioresistant MDA-MB-231 triple-negative breast cancer (TNBC) cells. NQO1 knockdown inhibited the proliferation of NQO1 expressing Hs578t TNBC cells or the radioresistant MDA-MB-231 cells, whereas NOQ1 overexpression increased the survival of MDA-MB-231 cells, which lack of NQO1 expression originally, under irradiation. The cytotoxicity of β-lapachone, an NQO1-dependent bioactivatable compound, was greater in radioresistant MDA-MB-231 cells than in parental cells. β-lapachone displayed a radiosensitization effect on Hs578t or radioresistant MBDA-MB-231 cells. The expression of the long noncoding RNA NEAT1 positively regulated the NQO1 expression in radioresistant MDA-MB-231 cells at a translational level rather than at a transcription level. The inhibition of the NEAT1 expression through the CRISPR-Cas9 method increased the sensitivity of radioresistant MDA-MB-231 cells to radiation and decreased their proliferation, the activity of cancer stem cells, and the expression of stemness genes, including BMI1, Oct4, and Sox2. In conclusion, the NQO1 expression in triple-negative breast cancer cells determined their radiosensitivity and was controlled by NEAT1. In addition, NOQ1 bioactivatable compounds displayed potential for application in the development of radiation sensitizers in breast cancer.

Topics: Cell Line, Tumor; Cell Proliferation; Cell Survival; Female; Gene Expression Regulation, Neoplastic; Gene Knockdown Techniques; Humans; NAD(P)H Dehydrogenase (Quinone); Naphthoquinones; Neoplastic Stem Cells; Radiation Tolerance; Radiation-Sensitizing Agents; RNA, Long Noncoding; Triple Negative Breast Neoplasms

Triple-negative breast cancer (TNBC) is a highly aggressive form of breast cancer (BC) and lacks targeted therapy and alternate therapeutic combinations. There is a necessity to increase disease-free survival in patients particularly within the first 5 years of diagnosis. 2,3-dichloro-5,8-dimethoxy-1,4-naphthoquinone (Z285), a novel 1,4 naphthoquinone analog, has been shown to have cytotoxic activity in BC cell lines and in combination with 4-hydroxytamoxifen (4-OHT). A known metabolite of tamoxifen, was postulated to decrease cell proliferation. Thus, this study investigates the use of Z285 and 4-OHT alone or in combination as a novel therapeutic alternative for TNBC.. Cell proliferation assays were performed on MDA-MB-231, Hs578T, MCF7 and HCC1806 cell lines at varying time points with Z285 and 4-OHT alone and in combination. Furthermore, ROS activity was measured to determine the changes in oxidative stress caused by both drugs.. The results showed dose- and time-dependent decreases in proliferation for all cell lines when treated with Z285, 4-OHT and their combination. Combinatorial analysis performed at 72 h using Synergyfinder. These promising results suggest the independent ability of each compound as a stand-alone chemotherapeutic agent, or in combinatorial therapy for the treatment of TNBC.

Topics: Apoptosis; Cell Line, Tumor; Cell Survival; Drug Synergism; Female; Humans; Inhibitory Concentration 50; Naphthoquinones; Reactive Oxygen Species; Tamoxifen; Triple Negative Breast Neoplasms

Triple-negative breast cancer (TNBC) is characterized by elevated metastasis, low survival, and poor response to therapy. Although many specific and effective agents for treating TNBC have been investigated, promising therapeutic options remain elusive. Here, we screened the inhibitory activities of three main components of Lithospermum erythrorhizon Sieb. et Zucc (shikonin, acetylshikonin, and β,β-dimethylacrylshikonin) on TNBC cells. The results revealed that shikonin potently decreased the viabilities of TNBC MDA-MB-231 and 4T1 cells but showed less cytotoxicity to normal mammary epithelial MCF-12A cells. Additionally, shikonin reversed the epithelial-to-mesenchymal transition (EMT) in MDA-MB-231 and 4T1 cells. Shikonin depressed cell migration and invasion, upregulated E-cadherin levels, downregulated N-cadherin, vimentin, and Snail levels, and reorganized the cytoskeletal proteins F-actin and vimentin. Shikonin reversed EMT by inhibiting activation of β-catenin signaling through attenuating β-catenin expression, nuclear accumulation, binding to T-cell factor consensus oligos, and transcription of its targeted EMT-related genes. Moreover, shikonin upregulated glycogen synthase kinase 3β (GSK-3β) levels, leading to enhanced phosphorylation and decreased levels of β-catenin. Furthermore, shikonin administration significantly inhibited lung metastasis of MDA-MB-231 cells in NOD/SCID mice accompanied by low systemic toxicity. Histological analysis confirmed that shikonin elevated levels of E-cadherin, phosphorylated β-catenin, and GSK-3β, and decreased levels of vimentin and β-catenin in pulmonary metastatic foci. These results indicated that shikonin potently inhibits TNBC metastasis by targeting the EMT via GSK-3β-regulated suppression of β-catenin signaling, which highlights the importance of shikonin as a potential candidate for novel anticancer therapeutics against TNBC.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; beta Catenin; Cell Line, Tumor; Dose-Response Relationship, Drug; Epithelial-Mesenchymal Transition; Female; Glycogen Synthase Kinase 3 beta; Mice; Mice, Inbred NOD; Mice, SCID; Naphthoquinones; Signal Transduction; Triple Negative Breast Neoplasms

Breast cancer (BC) is the second leading cause of death among women in the US, and its subtype triple-negative BC (TNBC) is the most aggressive BC with poor prognosis. In the current study, we investigated the anticancer effects of the natural product plumbagin (PL) on racially different TNBC cells. The PL effects were examined in two TNBC cell lines: MDA-MB-231 (MM-231) and MDA-MB-468 (MM-468), representing Caucasian Americans and African Americans, respectively. The results obtained indicate that PL inhibited cell viability and cell proliferation and induced apoptosis in both cell lines. Notably, MM-468 cells were 5-fold more sensitive to PL than MM-231 cells were. Testing PL and Taxol® showed the superiority of PL over Taxol® as an antiproliferative agent in MM-468 cells. PL treatment resulted in an approximately 20-fold increase in caspase-3 activity with 3 μM PL in MM-468 cells compared with an approximately 3-fold activity increase in MM-231 cells with 8 μM PL. Moreover, the results indicate a higher sensitivity to PL in MM-468 cells than in MM-231 cells. The results also show that PL downregulated CCL2 cytokine expression in MM-468 cells by 30% compared to a 90% downregulation in MM-231 cells. The ELISA results confirmed the array data (35% vs. 75% downregulation in MM-468 and MM-231 cells, respectively). Moreover, PL significantly downregulated IL-6 and GM-CSF in the MM-231 cells. Indeed, PL repressed many NF-қB-regulated genes involved in the regulation of apoptosis, proliferation, invasion, and metastasis. The compound significantly downregulated the same genes (BIRC3, CCL2, TLR2, and TNF) in both types of cells. However, PL impacted five more genes in MM-231 cells, including BCL2A1, ICAM1, IKBKE, IL1β, and LTA. In conclusion, the data obtained in this study indicate that the quinone compound PL could be a novel cancer treatment for TNBC in African American women.

Topics: Antineoplastic Agents, Phytogenic; Apoptosis; Black or African American; Caspase 3; Cell Line, Tumor; Cell Proliferation; Cell Survival; Chemokine CCL2; Female; Humans; Naphthoquinones; NF-kappa B; Paclitaxel; RNA, Messenger; Signal Transduction; Triple Negative Breast Neoplasms; Tumor Necrosis Factor-alpha; White People

Resistance to cell death and reprogramming of metabolism are important in neoplastic cells. Increased resistance to apoptosis and recurrence of tumors are the major roadblocks to effective treatment of triple negative breast cancer. It has been thought that execution of necroptosis involves ROS generation and mitochondrial dysfunction in malignant cells. In this study, the effect of shikonin, an active substance from the dried root of Lithospermum erythrorhizon, on the induction of necroptosis or apoptosis, via RIP1K-RIP3K expressions has been examined in the triple negative breast cancer cell line. The expression levels of RIP1K and RIP3K, caspase-3 and caspase-8 activities, the levels of ROS, and mitochondrial membrane potential have been studied in the shikonin-treated MDA-MB-468 cell line. An increase in the ROS levels and a reduction in mitochondrial membrane potential have been observed in the shikonin-treated cells. Cell death has mainly occurred through necroptosis with a significant increase in the RIP1K and RIP3K expressions, and characteristic morphological changes have been observed. In the presence of Nec-1, caspase-3 mediating apoptosis has occurred in the shikonin-treated cells. The current findings have revealed that shikonin provoked mitochondrial ROS production in the triple negative breast cancer cell line, which works as a double-edged executioner's ax in the execution of necroptosis or apoptosis. The main route of cell death induced by shikonin is RIP1K-RIP3K-mediated necroptosis, but in the presence of Nec-1, apoptosis has prevailed. The present results shed a new light on the possible treatment of drug-resistant triple negative breast cancer.

Topics: Antineoplastic Agents; Apoptosis; Caspase 3; Caspase 8; Cell Cycle Checkpoints; Cell Line, Tumor; Cell Shape; Cell Survival; Female; Gene Expression; Gene Expression Regulation, Neoplastic; Humans; Membrane Potential, Mitochondrial; Naphthoquinones; Reactive Oxygen Species; Receptor-Interacting Protein Serine-Threonine Kinases; Triple Negative Breast Neoplasms; Up-Regulation

We have earlier shown that Plumbagin (PB) can induce selective cytotoxicity to BRCA1 defective ovarian cancer cells; however, the effect of this molecule in BRCA1 mutated breast cancers has not been analyzed yet. Here, we report that reactive oxygen species (ROS) induced by PB resulted in DNA DSB and activates downstream signaling by ATR/ATM kinases and subsequent apoptosis. PB reduces DNA- dependent protein kinase (DNA-PK) expression and inhibits NHEJ (Non Homologous End Joining) activity in BRCA1 defective breast cancer cells. Also, PB induces apoptosis in two different BRCA1 conditional knock out murine models: MMTV-Cre; BRCA1(Co/Co) and WAP-Cre; BRCA1(Co/Co), at 2 mg/kg body weight, but 32 mg/kg of carboplatin (CN) was needed to induce apoptosis in them. This is the first study where two different tissue specific promoter driven transgenic mice models with BRCA1 exon 11 deletions are used for preclinical drug testing. The apoptosis induced by PB in HR (Homologous Recombination) defective triple negative BRCA1 mutant cell lines and in mouse models occur by inducing ROS mediated DNA DSB. The toxicity profile as compared with CN in transgenic mice provides evidence for PB's safer disposition as a therapeutic lead in breast cancer drug development.

Topics: Animals; Apoptosis; BRCA1 Protein; Cell Line, Tumor; DNA Breaks, Double-Stranded; Female; Humans; Mammary Neoplasms, Experimental; Mice; Mice, Knockout; Naphthoquinones; Triple Negative Breast Neoplasms; Tumor Suppressor Proteins

Because available treatments have limited efficacy in triple-negative breast cancer (TNBC), the identification of new therapeutic strategies to improve patients' outcome is urgently needed. In our study, we investigated the effects of the administration of the small molecule selective survivin suppressant YM155, alone or in association with CD34+ cells transduced with a replication-deficient adenovirus encoding the human tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) gene (CD34-TRAIL+ cells), in three TNBC cell models. YM155 exposure significantly impaired TNBC cell growth and selectively modulated survivin expression at both mRNA and protein level. In addition, co-culturing YM155-treated TNBC cells with CD34-TRAIL+ cells resulted in markedly increased cytotoxic effect and apoptotic response in comparison with single treatments. Such a chemosensitizing effect was observed only in TNBC cells inherently expressing DR5 and relied on the ability of YM155 to upregulate DR5 expression through a p38 MAPK- and CHOP-dependent mechanism. YM155/CD34-TRAIL+ combination also showed a significant inhibitory effect on the growth of DR5-expressing TNBC cells following xenotransplantation into NOD/SCID mice, in the absence of toxicity. Overall, our data (i) provide, for the first time, evidence that YM155 sensitizes TNBC cells to CD34-TRAIL+ cells-induced apoptosis by a mechanism involving the downregulation of survivin and the simultaneous p38 MAPK- and CHOP-mediated upregulation of DR5, and (ii) suggest the combination of YM155 with TRAIL-armed CD34+ progenitor cells as a promising therapeutic option for patients with TNBC expressing DR5.

Topics: Animals; Apoptosis; Blotting, Western; Cell Membrane; Cell Proliferation; Female; Flow Cytometry; Gene Expression Regulation, Neoplastic; Humans; Imidazoles; Inhibitor of Apoptosis Proteins; Mice; Mice, Inbred NOD; Mice, SCID; Naphthoquinones; p38 Mitogen-Activated Protein Kinases; Reactive Oxygen Species; Receptors, TNF-Related Apoptosis-Inducing Ligand; Survivin; TNF-Related Apoptosis-Inducing Ligand; Transcription Factor CHOP; Triple Negative Breast Neoplasms; Tumor Cells, Cultured; Xenograft Model Antitumor Assays

β-Lapachone (β-lap), a novel radiosensitizer with potent antitumor efficacy alone, selectively kills solid cancers that over-express. quinone oxidoreductase 1 (NQO1). Since breast or other solid cancers have heterogeneous NQO1 expression, therapies that reduce the resistance (e.g., NQO1(low)) of tumor cells will have significant clinical advantages. We tested whether NQO1-proficient (NQO1(+)) cells generated sufficient hydrogen peroxide (H2O2) after β-lap treatment to elicit bystander effects, DNA damage, and cell death in neighboring NQO1(low) cells.. β-Lap showed NQO1-dependent efficacy against two triple-negative breast cancer (TNBC) xenografts. NQO1 expression variations in human breast cancer patient samples were noted, where ~60% cancers over-expressed NQO1, with little or no expression in associated normal tissue. Differential DNA damage and lethality were noted in NQO1(+) versus NQO1-deficient (NQO1(-)) TNBC cells and xenografts after β-lap treatment. β-Lap-treated NQO1(+) cells died by programmed necrosis, whereas co-cultured NQO1(-) TNBC cells exhibited DNA damage and caspase-dependent apoptosis. NQO1 inhibition (dicoumarol) or H2O2 scavenging (catalase [CAT]) blocked all responses. Only NQO1(-) cells neighboring NQO1(+) TNBC cells responded to β-lap in vitro, and bystander effects correlated well with H2O2 diffusion. Bystander effects in NQO1(-) cells in vivo within mixed 50:50 co-cultured xenografts were dramatic and depended on NQO1(+) cells. However, normal human cells in vitro or in vivo did not show bystander effects, due to elevated endogenous CAT levels. Innovation and Conclusions: NQO1-dependent bystander effects elicited by NQO1 bioactivatable drugs (β-lap or deoxynyboquinone [DNQ]) likely contribute to their efficacies, killing NQO1(+) solid cancer cells and eliminating surrounding heterogeneous NQO1(low) cancer cells. Normal cells/tissue are protected by low NQO1:CAT ratios.

Topics: Animals; Bystander Effect; Female; Humans; Mice; Mice, Nude; NAD(P)H Dehydrogenase (Quinone); Naphthoquinones; Oxidation-Reduction; Quinones; Radiation-Sensitizing Agents; Triple Negative Breast Neoplasms; Tumor Cells, Cultured; Xenograft Model Antitumor Assays

Triple-negative breast cancer (TNBC) has a poor prognosis compared to other subtypes, and effective treatment options are limited to cytotoxic agents, including microtubule-targeting agents, due to the lack of molecular targets. Here, we examined the combined effect of sepantronium bromide (YM155) and microtubule-targeting agents in TNBC models. The combination of YM155 with docetaxel showed synergistic antiproliferative and caspase 3/7-inducing effects in MRK-nu-1 and MDA-MB-453 human TNBC cell lines in vitro. YM155 also synergistically enhanced the efficacies of other microtubule-targeting agents, including paclitaxel and vinorelbine, which induced accumulation of survivin at the G2/M phase, whereas it did not affect the efficacy of doxorubicin. Combination treatment with YM155 and microtubule-targeting agents decreased the accumulation of survivin at the G2/M phase and induced greater apoptosis than either single agent alone. Further, combination treatment with YM155 and docetaxel also had a synergistic antitumor effect, achieving complete regression without exacerbation of body weight loss in all mice, in a MRK-nu-1 human TNBC xenograft model. These results suggest that survivin inhibition synergistically sensitize human TNBC cells to microtubule-targeting agents.

Topics: Animals; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Cell Line, Tumor; Docetaxel; Drug Synergism; Female; Humans; Imidazoles; Inhibitor of Apoptosis Proteins; Mice; Mice, Nude; Naphthoquinones; Survivin; Taxoids; Triple Negative Breast Neoplasms; Xenograft Model Antitumor Assays