Human Breast Tumor Cells Research Articles

Alkaloid Profiling, Anti-Enzymatic and Antiproliferative Activity of the Endemic Chilean Amaryllidaceae Phycella cyrtanthoides

This research aims to identify the alkaloid profile and to evaluate the enzyme inhibitory potential and antiproliferative effects of the Amaryllidaceae plant Phycella cyrtanthoides. The alkaloid extracts from bulbs and leaves were analyzed using ultrahigh performance liquid chromatography orbitrap mass spectrometry (UHPLC-Orbitrap-MS) analysis. A total of 70 alkaloids were detected in the P. cyrtanthoides’ extracts. The enzyme inhibition potential against cholinesterases (AChE: acetylcholinesterase, and BChE butyrylcholinesterase) and tyrosinase were studied. Bulbs displayed the best IC50 values against AChE (4.29 ± 0.03 µg/mL) and BChE (18.32 ± 0.03 µg/mL). These results were consistent with docking experiments with selected major compounds in the active sites of enzymes, while no activity was observed against tyrosinase enzyme. Antiproliferative effects were investigated against human cervical (HeLa), lung (A549, SW1573), colon (WiDr), and breast (HBL-100, T-47D) tumor cell lines. Bulbs and leaves were active in all cell lines (GI50 < 2.5 µg/mL). These findings suggest that the endemic Chilean plant P. cyrtanthoides contains diverse types of bioactive alkaloids with antiproliferative activities and inhibitory effects with potential therapeutic applications for neurodegenerative diseases

Comparison of characteristics and tumor targeting properties of extracellular vesicles derived from primary NK cells or NK-cell lines stimulated with IL-15 or IL-12/15/18

NK cell-based therapies have shown promise for hematological cancer forms, but their use against solid tumors is hampered by their poor ability to infiltrate the tumor. NK cells release extracellular vesicles (EVs) containing cytolytic proteins, indicating that NK-cell derived EVs may have therapeutic potential. In this study, we compared the tumor-targeting potential of EVs derived from either primary NK cells or the NK cell lines NK-92 and KHYG-1 cultured in IL-15 alone or in combination with IL-12 and IL-18. Primary NK cells were also stimulated through the activating receptor CD16. Tumor cell apoptosis was measured using a panel of human colon, melanoma, glioblastoma, prostate, breast, and ovarian tumor cell line spheroids. NK cells or NK-92 cells stimulated with IL-12, IL-15, and IL-18 generated EVs with higher efficiency than EVs from resting cells, although similar amounts of EVs were produced under both conditions. Proteomic analysis indicated similar distribution of cytolytic proteins in EVs from primary NK cells and NK-92, but lower levels in KHYG-1 EVs that translated into poor capacity for KHYG-1 EVs at targeting tumor cell lines. Further, we show that CD16-stimulated NK cells release low amounts of EVs devoid of cytolytic proteins. Importantly, EVs from cytokine-stimulated NK cells penetrate into the spheroid core, and tumor spheroid susceptibility to NK-cell derived EVs was linked to differential expression of the NKG2D ligands MICA/B, which was blocked with an anti-NKG2D antibody. We conclude that EVs from activated primary NK cells or NK-92 cells has the best potential to infiltrate and target solid tumors.

Synergistic Effect of Squalene and Hydroxytyrosol on Highly Invasive MDA-MB-231 Breast Cancer Cells.

Several studies relate Mediterranean diet and virgin olive oil (VOO) intake with lower risk of several chronic diseases, including breast cancer. Many of them described antitumor properties of isolated minor compounds present in VOO, but beneficial properties of VOO arise from the effects of all its compounds acting together. The aim of the present study was to test the antitumor effects of two minor compounds from VOO (hydroxytyrosol (HT) and squalene (SQ)) on highly metastatic human breast tumor cells (MDA-MB-231) when acting in combination. Both isolated compounds were previously analyzed without showing any antitumoral effect on highly invasive MDA-MB-231 breast cancer cells, but the present results show that HT at 100 µM, combined with different concentrations of SQ, could exert antitumor effects. When they are combined, HT and SQ are able to inhibit cell proliferation, promoting apoptosis and DNA damage in metastatic breast cancer cells. Therefore, our results suggest that the health-promoting properties of VOO may be due, at least in part, to the combined action of these two minor compounds.

Cetylpyridinium chloride inhibits human breast tumor cells growth in a no-selective way.

Analyze the antitumor capacity of cetylpyridinium chloride (CPC) on human breast tumor cells, and the possible action mechanism. The human breast tumor cells MCF-7 and no-tumor breast cells MCF-10A were exposed to CPC under various condition (concentration and duration). Cell viability was measured with MTT assay, the LIVE/DEAD assay, and fluorescence microscopy. Membrane permeability after CPC exposure was evaluated by Calcein AM assay, mitochondrial morphology with a MitoView staining, and genotoxicity with the comet assay and fluorescence microscopy. CPC was cytotoxic to both MCF-7 and MCF-10A as of a 24-h exposure to 0.1 µM. Cytotoxicity was dose-dependent and reached 91% for MCF-7 and 78% for MCF-10A after a 24-h exposure to 100 µM CPC, which outperformed the positive control doxorubicin in effectiveness and selectivity. The LD50 of CPC on was 6 µM for MCF-7 and 8 µM for MCF-10A, yielding a selectivity index of 1.41. A time response analysis revealed 64% dead cells after only 5 min of exposure to 100 µM CPC. With respect to the action mechanisms, the comet assay did not reveal genome fragmentation. On the other hand, membrane damage was dose-dependent and may also affect mitochondrial morphology. Cetylpyridinium chloride inhibits MCF-7 cell growing in a non-selective way as of 5 min of exposure. The action mechanism of CPC on tumor cells involves cell membrane damage without change neither mitochondrial morphology nor genotoxicity.

Synthesis, crystal structure, DFT and anticancer study of dihydroartermisinin-paracetamol hybrids

A pair of C-10 epimers of dihydroartermisinin-paracetamol hybrids (A and B) were prepared in this work, and both of which were characterized by MS, 1H NMR, 13C NMR, IR and ECD spectra as well as by a single crystal X-ray structural analysis. Subsequently, the structures of the two compounds were analyzed with DFT-based approaches. The analytical results on conformations indicated that the DFT-optimized molecular structures were consistent with the crystal structures confirmed by X-ray diffraction. The packing of the molecules in the solid state was stabilized by hydrogen bonds. The signs of the experimental IR and ECD spectra was also efficiently simulated by the DFT methods. A primary evaluation on anticancer effects of A and B was conducted towards human breast tumor cell line MCF-7 and human colon tumor cell line HCT116, the results demonstrated that 10-α-O-(4-acetylamino) phenyl dihydroartemisinin (A) was slightly less potent than its 10-β counterpart (B) in both tested cell lines.

Triple Targeting of Breast Tumors Driven by Hormonal Receptors and HER2.

Breast cancers that express hormonal receptors (HR) and HER2 display resistance to targeted therapy. Tumor-promotional signaling from the HER2 and estrogen receptor (ER) pathways converges at the cyclin D1 and cyclin-dependent kinases (CDK) 4 and 6 complex, which drives cell-cycle progression and development of therapeutic resistance. Therefore, we hypothesized that co-targeting of ER, HER2, and CDK4/6 may result in improved tumoricidal activity and suppress drug-resistant subclones that arise on therapy. We tested the activity of the triple targeted combination therapy with tucatinib (HER2 small-molecule inhibitor), palbociclib (CKD4/6 inhibitor), and fulvestrant (selective ER degrader) in HR+/HER2+ human breast tumor cell lines and xenograft models. In addition, we evaluated whether triple targeted combination prevents growth of tucatinib or palbociclib-resistant subclones in vitro and in vivo Triple targeted combination significantly reduced HR+/HER2+ tumor cell viability, clonogenic survival, and in vivo growth. Moreover, survival of HR+/HER2+ cells that were resistant to the third drug in the regimen was reduced by the other two drugs in combination. We propose that a targeted triple combination approach will be clinically effective in the treatment of otherwise drug-resistant tumors, inducing robust responses in patients.

Type-3 Hyaluronan Synthase Attenuates Tumor Cells Invasion in Human Mammary Parenchymal Tissues.

The microenvironment for tumor growth and developing metastasis should be essential. This study demonstrated that the hyaluronic acid synthase 3 (HAS3) protein and its enzymatic product hyaluronic acid (HA) encompassed in the subcutaneous extracellular matrix can attenuate the invasion of human breast tumor cells. Decreased HA levels in subcutaneous Has3-KO mouse tissues promoted orthotopic breast cancer (E0771) cell-derived allograft tumor growth. MDA-MB-231 cells premixed with higher concentration HA attenuate tumor growth in xenografted nude mice. Human patient-derived xenotransplantation (PDX) experiments found that HA selected the highly migratory breast cancer cells with CD44 expression accumulated in the tumor/stroma junction. In conclusion, HAS3 and HA were detected in the stroma breast tissues at a high level attenuates effects for induced breast cancer cell death, and inhibit the cancer cells invasion at the initial stage. However, the highly migratory cancer cells were resistant to the HA-mediated effects with unknown mechanisms.

An Aptamer-Modified DNA Tetrahedron-Based Nanogel for Combined Chemo/Gene Therapy of Multidrug-Resistant Tumors.

DNA-based nanogels have attracted much attention in the biomedical research field. Herein, we report a universal strategy for the fabrication of an aptamer-modified DNA tetrahedron (TET)-based nanogel for combined chemo/gene therapy of multidrug-resistant tumors. In our design, terminal extended antisense oligonucleotides (ASOs) are employed as the linker to co-assemble with two kinds of three-vertex extended TETs for the efficient construction of the DNA-based nanogel. With the incorporation of an active cell-targeting group (aptamer in one vertex of TET) and a controlled-release element (disulfide bridges in the terminals of ASOs), the functional DNA-based nanogel can achieve targeted cellular internalization and stimuli-responsive release of embedded ASOs. After loading with the chemodrug (doxorubicin (DOX), an intercalator of double-stranded DNA), the multifunctional DOX/Nanogel elicits efficient chemo/gene therapy of human MCF-7 breast tumor cells with DOX resistance (MCF-7R). This aptamer-modified DNA tetrahedron-based nanogel provides another strategy for intelligent drug delivery and combined tumor therapy.

STAT3 as a Potential Target for Tumor Suppressive Effects of 15-Deoxy-Δ12,14-prostaglandin J2 in Triple Negative Breast Cancer.

STAT3 plays a prominent role in proliferation and survival of tumor cells. Thus, STAT3 has been considered to be a prime target for development of anti-cancer therapeutics. The electrophilic cyclopentenone prostaglandin,15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2) has been well recognized for its capability to modulate intracellular signaling pathways involved in cancer cell growth and progression. We previously reported that 15d-PGJ2 had potent cytotoxicity against harvey-ras transformed human mammary epithelial cells through direct interaction with STAT3. In this study, we have attempted to verify the inhibitory effects of 15d-PGJ2 on STAT3 signaling in human breast tumor cells. The triple negative breast cancer cell lines, MDA-MB-231 and MDA-MB-468 displaying constitutive phosphorylation of STAT3 on the tyrosine 705 (Tyr705) residue, underwent apoptosis upon inhibition of STAT3 by 15d-PGJ2. In contrast, estrogen receptor positive MCF-7 breast cancer cells that do not exhibit elevated STAT3 phosphorylation were much less susceptible to 15d-PGJ2-induced apoptosis as assessed by PARP cleavage. Furthermore, 15d-PGJ2 inhibited interleukin-6-induced tyrosine phosphorylation of STAT3 in LNCaP cells. According to molecular docking studies, 15d-PGJ2 may preferentially bind to the cysteine 259 residue (Cys259) present in the coiled-coil domain of STAT3. Site-directed mutagenesis of STAT3 identified Cys259 to be the critical amino acid for the 15d-PGJ2-induced apoptosis as well as epithelial-to-mesenchymal transition. Taken together, these findings suggest STAT3 inactivation through direct chemical modification of its Cys259 as a potential therapeutic approach for treatment of triple negative breast cancer treatment.

Condensed ECM-based nanofilms on highly permeable PET membranes for robust cell-to-cell communications with improved optical clarity

The properties of a semipermeable porous membrane, including pore size, pore density, and thickness, play a crucial role in creating a tissue interface in a microphysiological system (MPS) because it dictates multicellular interactions between different compartments. The small pore-sized membrane has been preferentially used in an MPS for stable cell adhesion and the formation of tissue barriers on the membrane. However, it limited the applicability of the MPS because of the hindered cell transmigration via sparse through-holes and the optical translucence caused by light scattering through pores. Thus, there remain unmet challenges to construct a compartmentalized MPS without those drawbacks. Here we report a submicrometer-thickness (∼500 nm) fibrous extracellular matrix (ECM) film selectively condensed on a large pore-sized track-etched (TE) membrane (10 µm-pores) in an MPS device, which enables the generation of functional tissue barriers simultaneously achieving optical transparency, intercellular interactions, and transmigration of cells across the membrane. The condensed ECM fibers uniformly covering the surface and 10 µm-pores of the TE membrane permitted sufficient surface areas where a monolayer of the human induced pluripotent stem cell-derived brain endothelial cells is formed in the MPS device. The functional maturation of the blood–brain barrier (BBB) was proficiently achieved due to astrocytic endfeet sheathing the brain endothelial cells through 10 µm pores of the condensed-ECM-coated TE (cECMTE) membrane. We also demonstrated the extravasation of human metastatic breast tumor cells through the human BBB on the cECMTE membrane. Thus, the cECMTE membrane integrated with an MPS can be used as a versatile platform for studying various intercellular communications and migration, mimicking the physiological barriers of an organ compartment.

Selective CDK4/6 inhibition of novel 1,2,3-triazole tethered acridinedione derivatives induces G1/S cell cycle transition arrest via Rb phosphorylation blockade in breast cancer models

CDK4 & CDK6 are essential regulators of initial cell cycle phases and are always considered an exciting choice for anti-cancer therapy. In the present study, we presented the structure-based rational design & synthesis of a new class of 1,2,3-triazole tethered acridinedione derivatives (6a-l) as selective CDK4/6 inhibitors. Title molecules were prepared as a result of the rate-determining reaction between substituted derivatives of 1-Phenyl-1H-1,2,3-triazole-4-carbaldehydes and substituted dimedones, and the molecules were structurally characterized by IR, 1H,13C NMR, and MS spectral data. All molecules were screened for in-vitro cytotoxic potential against a group of human breast tumor cell lines of distinct origin with differential Rb expression status. Out of entire series of conjugated hexahydro acridinediones, 6g showed potent cytotoxic effect against MCF-7, BT-474, and SK-BR3 cell lines with IC50values 0.173 ± 0.037, 0.117 ± 0.025, and 0.136 ± 0.027 μM, respectively. Further, CDK inhibition assays revealed that the compounds 6g and 6h selectively inhibit CDK4/6 over other CDK-parter complexes of the family against the selected cell line group except for MDA-MB468 cells. Furthermore, apoptotic evaluation and cell cycle analysis determined that compound 6g successfully triggered apoptosis in all examined cell lines except MDA-MB468 through blocking G1/S cell cycle transformation. In addition, compound 6g showed the highest in-vitro selectivity towards CDK4/6 inhibition, even compared with Abemaciclib, and it was also proved for favourable in-vivo pharmacokinetic properties in male albino mice. Furthermore, molecule 6g showed promising tumor growth suppression with lower adverse effects in MCF-7 xenograft mice models, which could competently be considered as a novel chemotherapeutic candidate for a further comprehensive preclinical study involving breast cancer therapy.

IL-9 Abrogates the Metastatic Potential of Breast Cancer by Controlling Extracellular Matrix Remodeling and Cellular Contractility.

IL-9 is produced by Th9 cells and is classically known as a growth-promoting cytokine. Although protumorigenic functions of IL-9 are described in T cell lymphoma, recently, we and others have reported anti-tumor activities of IL-9 in melanoma mediated by mast cells and CD8+ T cells. However, involvement of IL-9 in invasive breast and cervical cancer remains unexplored. In this study, we demonstrate IL-9-dependent inhibition of metastasis of both human breast (MDA-MB-231 and MCF-7) and cervical (HeLa) tumor cells in physiological three-dimensional invasion assays. To dissect underlying mechanisms of IL-9-mediated suppression of invasion, we analyzed IL-9-dependent pathways of cancer cell metastasis, including proteolysis, contractility, and focal adhesion dynamics. IL-9 markedly blocked tumor cell-collagen degradation, highlighting the effects of IL-9 on extracellular matrix remodeling. Moreover, IL-9 significantly reduced phosphorylation of myosin L chain and resultant actomyosin contractility and also increased focal adhesion formation. Finally, IL-9 suppressed IL-17- and IFN-γ-induced metastasis of both human breast (MDA-MB-231) and cervical (HeLa) cancer cells. In conclusion, IL-9 inhibits the metastatic potential of breast and cervical cancer cells by controlling extracellular matrix remodeling and cellular contractility.

Downregulation of Kynurenine 3-Monooxygenase Inhibits cancer stemness-related genes in both human and canine breast tumor cell lines

Downregulation of Kynurenine 3-Monooxygenase Inhibits cancer stemness-related genes in both human and canine breast tumor cell lines

ASN004, A 5T4-targeting scFv-Fc Antibody-Drug Conjugate with High Drug-to-Antibody Ratio, Induces Complete and Durable Tumor Regressions in Preclinical Models.

The 5T4 oncofetal antigen (trophoblast glycoprotein) is expressed in a wide range of malignant tumors but shows very limited expression in normal adult tissues. ASN004 is a 5T4-targeted antibody-drug conjugate (ADC) that incorporates a novel single-chain Fv-Fc antibody and Dolaflexin drug-linker technology, with an Auristatin F hydroxypropylamide payload drug-to-antibody ratio of approximately 10-12. The pharmacology, toxicology, and pharmacokinetic properties of ASN004 and its components were investigated in vitro and in vivo ASN004 showed high affinity for the 5T4 antigen and was selectively bound to and internalized into 5T4-expressing tumor cells, and potent cytotoxicity was demonstrated for a diverse panel of solid tumor cell lines. ASN004 induced complete and durable tumor regression in multiple tumor xenograft models, derived from human lung, breast, cervical, and gastric tumor cell lines having a wide range of 5T4 expression levels. A single dose of ASN004, as low as 1 mg/kg i.v., achieved complete tumor regression leading to tumor-free survivors in the A431 cervical cancer model. In head-to-head studies, superior activity of ASN004 was demonstrated against trastuzumab-DM1, in a low-5T4/high-HER2 expressing gastric tumor model, and 10-fold greater potency was found for ASN004 against the 5T4-targeted ADC PF-06263507 in a lung tumor model. In marmoset monkeys, ASN004 was well tolerated at doses up to 1.5 mg/kg Q3W i.v., and showed dose-dependent exposure, linear pharmacokinetics, and markedly low exposure of free payload drug. Taken together, these findings identify ASN004 as a promising new ADC therapeutic for clinical evaluation in a broad range of solid tumor types.

A novel heterocyclic compound inhibits human breast tumor cells via ROS mediated apoptosis

The new heterocyclic compound 2-((6-chloro-2-methylpyrimidin-4-yl)amino)-N-(2-chloro-6-methylphenyl) thiazole-5-carboxamide (1), designed using 2-chloro-N-(2-chloro-6-methylphenyl)thiazole-5-carboxamide (2) as start material, was successfully obtained via multistep synthesis route and finally characterized by IR (infrared radiation), 1H NMR (nuclear magnetic resonance), and single crystal X-ray crystallography. The inhibitory effect of compound 1 on human breast tumor cell line BS524 was further explored. The MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and IC50 (half maximal inhibitory concentration) values suggested that compound 1 has significant anti-proliferation activity on BS524 cells and with low side effect. Then, serial experiments, such as the Annexin V-FITC/PI assay, TUNEL staining and autophagy detection revealed that compound 1 could inhibit cell proliferation via induce cells apoptosis, and the apoptosis is induced by (reactive oxygen species) ROS generation in BS524 cells.

Loss of the Metastasis Suppressor NME1, But Not of Its Highly Related Isoform NME2, Induces a Hybrid Epithelial-Mesenchymal State in Cancer Cells.

Epithelial–mesenchymal transition (EMT) is important for the initial steps of metastasis. Although it is well accepted that the nucleoside diphosphate kinase NME1 is a metastasis suppressor, its effect on EMT remains poorly documented, as does that of its closely related isoform, NME2. Here, by using gene silencing, inactivation and overexpression strategies in a variety of cellular models of cancer, we show that NME1 is a powerful inhibitor of EMT. Genetic manipulation of NME2, by contrast, had no effect on the EMT phenotype of cancer cells, indicating a specific function of NME1 in EMT regulation. Loss of NME1 in epithelial cancer cells resulted in a hybrid phenotype intermediate between epithelial and mesenchymal cells, which is known to be associated with cells with a highly metastatic character. Conversely, overexpression of NME1 in mesenchymal cancer cells resulted in a more epithelial phenotype. We found that NME1 expression was negatively associated with EMT markers in many human cancers and was reduced in human breast tumor cell lines with the aggressive ‘triple-negative’ phenotype when compared to human breast tumor cell lines positive for estrogen receptor. We show that NME1, but not NME2, is an inhibitor of essential concerted intracellular signaling pathways involved in inducing EMT, including the AKT and MAPK (ERK, p38, and JNK) pathways. Additionally, NME1 depletion considerably altered the distribution of E-cadherin, a gatekeeper of the epithelial phenotype, shifting it from the plasma membrane to the cytosol and resulting in less E-cadherin on the cell surface than in control cells. Functional aggregation and dispersion assays demonstrated that inactivation of NME1 decreases E-cadherin-mediated cell–cell adhesion. We conclude that NME1, but not NME2, acts specifically to inhibit EMT and prevent the earliest stages of metastasis.

POU1F1 transcription factor induces metabolic reprogramming and breast cancer progression via LDHA regulation

Metabolic reprogramming is considered hallmarks of cancer. Aerobic glycolysis in tumors cells has been well-known for almost a century, but specific factors that regulate lactate generation and the effects of lactate in both cancer cells and stroma are not yet well understood. In the present study using breast cancer cell lines, human primary cultures of breast tumors, and immune deficient murine models, we demonstrate that the POU1F1 transcription factor is functionally and clinically related to both metabolic reprogramming in breast cancer cells and fibroblasts activation. Mechanistically, we demonstrate that POU1F1 transcriptionally regulates the lactate dehydrogenase A (LDHA) gene. LDHA catalyzes pyruvate into lactate instead of leading into the tricarboxylic acid cycle. Lactate increases breast cancer cell proliferation, migration, and invasion. In addition, it activates normal-associated fibroblasts (NAFs) into cancer-associated fibroblasts (CAFs). Conversely, LDHA knockdown in breast cancer cells that overexpress POU1F1 decreases tumor volume and [18F]FDG uptake in tumor xenografts of mice. Clinically, POU1F1 and LDHA expression correlate with relapse- and metastasis-free survival. Our data indicate that POU1F1 induces a metabolic reprogramming through LDHA regulation in human breast tumor cells, modifying the phenotype of both cancer cells and fibroblasts to promote cancer progression.

Tumor-specific overexpression of histone gene, H3C14 in gastric cancer is mediated through EGFR-FOXC1 axis

Incorporation of different H3 histone isoforms/variants have been reported to differentially regulate gene expression via alteration in chromatin organization during diverse cellular processes. However, the differential expression of highly conserved histone H3.2 genes, H3C14 and H3C13 in human cancer has not been delineated. In this study, we investigated the expression of H3.2 genes in primary human gastric, brain, breast, colon, liver, and head and neck cancer tissues and tumor cell lines. The data showed overexpression of H3.2 transcripts in tumor samples and cell lines with respect to normal counterparts. Furthermore, TCGA data of individual and TCGA PANCAN cohort also showed significant up-regulation of H3.2 genes. Further, overexpressed H3C14 gene coding for H3.2 protein was regulated by FOXC1 transcription factor and G4-cassette in gastric cancer cell lines. Elevated expression of FOXC1 protein and transcripts were also observed in human gastric cancer samples and cell lines. Further, FOXC1 protein was predominantly localized in the nuclei of neoplastic gastric cells compared to normal counterpart. In continuation, studies with EGF induction, FOXC1 knockdown, and ChIP-qPCR for the first time identified a novel axis, EGFR-FOXC1-H3C14 for regulation of H3C14 gene overexpression in gastric cancer. Therefore, the changes the epigenomic landscape due to incorporation of differential expression H3 variant contributes to change in gene expression pattern and thereby contributing to pathogenesis of cancer.

Long-term dexamethasone treatment increases the engraftment efficiency of human breast cancer cells in adult zebrafish

The host immune system tends to reject xenogenic-implanted cells making tumor development in adult host animal models difficult. Immune system suppression is used for successful xenotransplantation of human cancer cells in many animal models. The studies of cancer development processes in vivo offer opportunities to understand cancer biology and discover new therapeutic strategies. In this context, zebrafish is a model that has been widely applied in the study of human diseases, such as cancer. However, the long-term immunosuppression of these adult zebrafish is still under study as a xenograft animal model for human cancer. This work aimed to evaluate the effects of 21 days of (long-term) exposure of dexamethasone in zebrafish-transplanted with MGSO-3 cells, human breast tumor cell line. Our results show that the animals, while kept on dexamethasone treatment, remained with a 50% reduction in the number of peripheral lymphocytes. In vitro data demonstrated that up to 7 days of dexamethasone treatment did not alter the morphology, proliferation, or viability of MGSO-3 cells. The animals that received a prolonged dexamethasone treatment allowed the engraftment of tumor cells in 100% of the zebrafish tested. These animals also showed tumor progression over 21 days. The experimental group that received only previous exposure to dexamethasone had their tumors regressed after 14 days. In conclusion, the prolonged use of dexamethasone in zebrafish showed a potential strategy for in vivo monitoring of xenograft tumor growth for development studies, as well as in anticancer drug discovery.

Cytosolic Ca2+ transients during pulsed focused ultrasound generate reactive oxygen species and cause DNA damage in tumor cells.

Mechanical forces from non-ablative pulsed focused ultrasound (pFUS) generate pro-inflammatory tumor microenvironments (TME), marked by increased cytokines, chemokines, and trophic factors, as well as immune cell infiltration and reduced tumor growth. pFUS also causes DNA damage within tumors, which is a potent activator of immunity and could contribute to changes in the TME. This study investigated mechanisms behind the mechanotransductive effects of pFUS causing DNA damage in several tumor cell types.Methods: 4T1 (murine breast tumor), B16 (murine melanoma), C6 (rat glioma), or MDA-MB-231 (human breast tumor) cells were sonicated in vitro (1.1MHz; 6MPa PNP; 10ms pulses; 10% duty cycle; 300 pulses). DNA damage was detected by TUNEL, apoptosis was measured by immunocytochemistry for cleaved caspase-3. Calcium, superoxide, and H2O2 were detected by fluorescent indicators and modulated by BAPTA-AM, mtTEMPOL, or Trolox, respectively.Results: pFUS increased TUNEL reactivity (range = 1.6-2.7-fold) in all cell types except C6 and did not induce apoptosis in any cell line. All lines displayed cytosolic Ca2+ transients during sonication. pFUS increased superoxide (range = 1.6-2.0-fold) and H2O2 (range = 2.3-2.8-fold) in all cell types except C6. BAPTA-AM blocked increased TUNEL reactivity, superoxide and H2O2 formation, while Trolox also blocked increased TUNEL reactivity increased after pFUS. mtTEMPOL allowed H2O2 formation and did not block increased TUNEL reactivity after pFUS. Unsonicated C6 cells had higher baseline concentrations of cytosolic Ca2+, superoxide, and H2O2, which were not associated with greater baseline TUNEL reactivity than the other cell lines.Conclusions: Mechanotransduction of pFUS directly induces DNA damage in tumor cells by cytosolic Ca2+ transients causing formation of superoxide and subsequently, H2O2. These results further suggest potential clinical utility for pFUS. However, the lack of pFUS-induced DNA damage in C6 cells demonstrates a range of potential tumor responses that may arise from physiological differences such as Ca2+ or redox homeostasis.