The mouse mammary carcinoma 4T1: characterization of the cellular landscape of primary tumours and metastatic tumour foci

Effects of obesity on NK cells in a mouse model of postmenopausal breast cancer

Obesity is a widely spread disease and a crucial risk factor for malign disorders, including breast cancer of women in the postmenopause. Studies demonstrated that in case of obesity crucial natural killer (NK) cell functions like combating tumor cells are affected. This study aims to analyze NK cells and NK cell receptor expression of obese mice in a model for postmenopausal breast cancer. Therefore, female BALB/c mice were fed either a high fat or a standard diet. Thereafter, ovaries were ectomized and a syngeneic and orthotopical injection of 4T1-luc2 mouse mammary tumor cells into the mammary adipose tissue pad was performed. Obese mice showed increased body weights and visceral fat mass as well as increased levels of leptin and IL-6 in plasma. Moreover, compared to the lean littermates, tumor growth was increased and the NKp46-expression on circulating NK cells was decreased. Furthermore, the activating NK cell receptor NKG2D ligand (MULT1) expression was enhanced in adipose tissue of obese tumor bearing mice. The present study gives novel insights into gene expression of NK cell receptors in obesity and aims to promote possible links of the obesity-impaired NK cell physiology and the elevated breast cancer risk in obese women.

Mitochondrial DNA Affects the Expression of Nuclear Genes Involved in Immune and Stress Responses in a Breast Cancer Model

Tumor cells without mitochondrial (mt) DNA (ρ0 cells) are auxotrophic for uridine, and their growth is supported by pyruvate. While ATP synthesis in ρ0 cells relies on glycolysis, they fail to form tumors unless they acquire mitochondria from stromal cells. Mitochondrial acquisition restores respiration that is essential for de novo pyrimidine biosynthesis and for mitochondrial ATP production. The physiological processes that underpin intercellular mitochondrial transfer to tumor cells lacking mtDNA and the metabolic remodeling and restored tumorigenic properties of cells that acquire mitochondria are not well understood. Here, we investigated the changes in mitochondrial and nuclear gene expression that accompany mtDNA deletion and acquisition in metastatic murine 4T1 breast cancer cells. Loss of mitochondrial gene expression in 4T1ρ0 cells was restored in cells recovered from subcutaneous tumors that grew from 4T1ρ0 cells following acquisition of mtDNA from host cells. In contrast, the expression of most nuclear genes that encode respiratory complex subunits and mitochondrial ribosomal subunits was not greatly affected by loss of mtDNA, indicating ineffective mitochondria-to-nucleus communication systems for these nuclear genes. Further, analysis of nuclear genes whose expression was compromised in 4T1ρ0 cells showed that immune- and stress-related genes were the most highly differentially expressed, representing over 70% of those with greater than 16-fold higher expression in 4T1 compared with 4T1ρ0 cells. The monocyte recruiting chemokine, Ccl2, and Psmb8, a subunit of the immunoproteasome that generates MHCI-binding peptides, were the most highly differentially expressed. Early monocyte/macrophage recruitment into the tumor mass was compromised in 4T1ρ0 cells but recovered before mtDNA could be detected. Taken together, our results show that mitochondrial acquisition by tumor cells without mtDNA results in bioenergetic remodeling and re-expression of genes involved in immune function and stress adaptation.

Vitamin D Metabolite Profile in Cholecalciferol- or Calcitriol-Supplemented Healthy and Mammary Gland Tumor-Bearing Mice

To analyze if the prometastatic activity of calcitriol (active vitamin D₃ metabolite), which was previously observed in a 4T1 breast cancer model, is also found in other breast cancers, and to assess the impact of various schemes of vitamin D supply, we used 4T1 and E0771 mouse metastatic and 67NR nonmetastatic cells in this study. BALB/c and C57BL/6 healthy and tumor-bearing mice were exposed to a control (1000 IU), low- (100 IU), and high- (5000 IU) vitamin D₃ diets. Additionally, from day 7 of tumor transplantation, the 1000 and 100 IU groups were gavaged with calcitriol (+cal). After 8 weeks of feeding, plasma levels of 25(OH)D₃, 24,25(OH)₂D₃, and 3-epi-25(OH)D₃ were significantly lower in calcitriol-treated and vitamin D-deficient groups than in the control, whereas the levels of all metabolites were increased in the 5000 IU group. The ratio of 25(OH)D₃:24,25(OH)₂D₃ was increased in both calcitriol-treated groups, whereas the ratio of 25(OH)D₃:3-epi-25(OH)D₃ was increased only in the 100 IU group but decreased in the 5000 IU group. In contrast to E0771, 4T1 lung metastasis was accelerated in all vitamin D-supplemented mice, as well as in the deficient group with an increased inflammatory response. 67NR tumor growth was transiently inhibited in the 1000 IU+cal group, but single metastases were observed in the 5000 and 100 IU groups. Based on the results, we conclude that various schemes of vitamin D supply and vitamin D deficiency led to similar metabolite profiles irrespective of the mice strain and tumor burden. However, depending on the type of breast cancer, different effects on tumor growth and metastasis were noticed.

Encapsulating paclitaxel in polymeric nanomicelles increases antitumor activity and prevents peripheral neuropathy

Paclitaxel (PTX) has a great clinical significance as an antitumor drug, although several side effects are strongly dose-limiting. In this way, we prepared a PTX-loaded 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy (polyethylene glycol)-2000] polymeric micelles (PM/PTX) in an attempt to improve safety and effectiveness of conventional PTX formulation (CrEL/EtOH/PTX). In this study, we evaluated from both formulations: stability after dilution, hemocompatibility, cellular uptake, acute toxicity in healthy mice, antitumor activity, and toxicity after multiple-dose treatment. PM/PTX appeared to be more stable than CrEL/EtOH/PTX after dilution. PM/PTX did not exhibit hemolytic activity (values <1%), even at high concentrations. In vitro cellular uptake study indicated that polymeric micelles were able to deliver more PTX (5.8 %) than CrEL/EtOH (2.7 %) to 4T1 cells. In the acute toxicity evaluation in healthy mice, CrEL/EtOH/PTX (single dose of 20 mg/kg) induced peripheral neuropathy, which was not observed in PM/PTX group. Similar results were observed after tumor-bearing mice received a multiple-dose regimen (seven doses of 10 mg/kg). Worth mentioning, we also evaluated vehicles, and CrEL/EtOH alone was not capable of inducing neuropathic pain. Besides, PM/PTX exhibited a higher antitumor activity with an inhibition ratio approximately 1.5-fold higher than CrEL/EtOH/PTX group. This study suggested that PM/PTX is safer than CrEL/EtOH/PTX, and was able to improve the antitumor effectiveness in a 4T1 breast cancer model.

Safety and Clinical Impact of a Single Red Light Irradiation on Breast Tumor-Bearing Mice

Low-level light therapy has been used in health care as a therapeutic strategy for different diseases. However, its effects on cancer are controversial. This work evaluated the effects of three energies on breast cancer-bearing mice after a single red light-emitting diode (LED) irradiation. 4T1 cells were inoculated into the mammary fat pad of female BALB/c mice. When tumor volume reached 100 mm³ , animals were irradiated by a LED irradiator (660 ± 11 nm) with energies of 1.2, 3.6, and 6.0 J. Control without irradiation and healthy animals were also evaluated. Mice were monitored regarding tumor volume and total blood count. After euthanasia, their organs were examined. We observed that a single irradiation does not increase tumor volume. All irradiated groups exhibited better clinical conditions than control, which presented a significant decrease in platelet and red blood cell levels compared with healthy mice. The energy of 3.6 J arrested neutrophil-lymphocyte rate besides promoting longer survival and a lower number of metastatic nodules in the lungs. These findings suggest that a single red LED irradiation causes no impact on the course of the disease. Besides, the intermediary dose-effect should be further investigated since it seems to promote better outcomes on breast cancer-bearing mice.

Doxorubicin and Trifolium pratense L. (Red clover) extract synergistically inhibits brain and lung metastases in 4T1 tumor-bearing BALB/c mice

Trifolium pratense L. (Red clover-T. pratense) commonly consumed as a healthy beverage has been demonstrated to have various biological activities including antioxidant and anticancer effects. The aim of this study was to investigate the antimetastasis effects of doxorubicin (DOX) and T. pratense extract in 4T1 tumor-bearing BALB/c mice. In this study, 56 female BALB/c mice were randomly divided into seven groups (n = 8/group) to receive DOX and T. pratense extract in three different doses (100, 200, and 400 mg/kg/day) for 35 days. On day 36 after starting treatments, serum cytokines (IL-8 and IL-6) were measured. Immunohistochemical (IHC) staining was performed for GATA-3 in the brain and lung, and for CK5/6 in tumor tissues. Metastasis-related gene (matrix metalloproteinase-2 [MMP-2] and sirtuin-1 [SIRT-1]) expressions were also measured by real-time PCR. Our results showed that cotreatment with DOX and T. pratense extract improved stereological parameters (i.e., reduction in the volume of metastatic tumors) in the lung and brain and decreased the serum levels of inflammatory cytokines (IL-8 and IL-6). DOX and T. pratense extract synergistically down-regulated MMP-2 and up-regulated SIRT-1 genes, decreased the number of CK5/6-positive cells in tumor tissues, and inhibited metastasis of GATA-3-positive cells into the lung and brain. The combination of T. pratense extract and DOX synergistically inhibited the metastasis of 4T1 xenograft cells in a dose-dependent manner.

Ambrisentan, an endothelin receptor type A-selective antagonist, inhibits cancer cell migration, invasion, and metastasis

Several studies reported a central role of the endothelin type A receptor (ETAR) in tumor progression leading to the formation of metastasis. Here, we investigated the in vitro and in vivo anti-tumor effects of the FDA-approved ETAR antagonist, Ambrisentan, which is currently used to treat patients with pulmonary arterial hypertension. In vitro, Ambrisentan inhibited both spontaneous and induced migration/invasion capacity of different tumor cells (COLO-357 metastatic pancreatic adenocarcinoma, OvCar3 ovarian carcinoma, MDA-MB-231 breast adenocarcinoma, and HL-60 promyelocytic leukemia). Whole transcriptome analysis using RNAseq indicated Ambrisentan's inhibitory effects on the whole transcriptome of resting and PAR2-activated COLO-357 cells, which tended to normalize to an unstimulated profile. Finally, in a pre-clinical murine model of metastatic breast cancer, treatment with Ambrisentan was effective in decreasing metastasis into the lungs and liver. Importantly, this was associated with a significant enhancement in animal survival. Taken together, our work suggests a new therapeutic application for Ambrisentan in the treatment of cancer metastasis.

Aptamer targeted therapy potentiates immune checkpoint blockade in triple-negative breast cancer

BACKGROUND

Triple-negative breast cancer (TNBC) is a uniquely aggressive cancer with high rates of relapse due to resistance to chemotherapy. TNBC expresses higher levels of programmed cell death-ligand 1 (PD-L1) compared to other breast cancers, providing the rationale for the recently approved immunotherapy with anti-PD-L1 monoclonal antibodies (mAbs). A huge effort is dedicated to identify actionable biomarkers allowing for combination therapies with immune-checkpoint blockade. Platelet-derived growth factor receptor β (PDGFRβ) is highly expressed in invasive TNBC, both on tumor cells and tumor microenvironment. We recently proved that tumor growth and lung metastases are impaired in mouse models of human TNBC by a high efficacious PDGFRβ aptamer. Hence, we aimed at investigating the effectiveness of a novel combination treatment with the PDGFRβ aptamer and anti-PD-L1 mAbs in TNBC.

METHODS

The targeting ability of the anti-human PDGFRβ aptamer toward the murine receptor was verified by streptavidin-biotin assays and confocal microscopy, and its inhibitory function by transwell migration assays. The anti-proliferative effects of the PDGFRβ aptamer/anti-PD-L1 mAbs combination was assessed in human MDA-MB-231 and murine 4 T1 TNBC cells, both grown as monolayer or co-cultured with lymphocytes. Tumor cell lysis and cytokines secretion by lymphocytes were analyzed by LDH quantification and ELISA, respectively. Orthotopic 4 T1 xenografts in syngeneic mice were used for dissecting the effect of aptamer/mAb combination on tumor growth, metastasis and lymphocytes infiltration. Ex vivo analyses through immunohistochemistry, RT-qPCR and immunoblotting were performed.

RESULTS

We show that the PDGFRβ aptamer potentiates the anti-proliferative activity of anti-PD-L1 mAbs on both human and murine TNBC cells, according to its human/mouse cross-reactivity. Further, by binding to activated human and mouse lymphocytes, the aptamer enhances the anti-PD-L1 mAb-induced cytotoxicity of lymphocytes against tumor cells. Importantly, the aptamer heightens the antibody efficacy in inhibiting tumor growth and lung metastases in mice. It acts on both tumor cells, inhibiting Akt and ERK1/2 signaling pathways, and immune populations, increasing intratumoral CD8 + T cells and reducing FOXP3 + Treg cells.

CONCLUSION

Co-treatment of PDGFRβ aptamer with anti-PD-L1 mAbs is a viable strategy, thus providing for the first time an evidence of the efficacy of PDGFRβ/PD-L1 co-targeting combination therapy in TNBC.

Differential Impact of Calcitriol and Its Analogs on Tumor Stroma in Young and Aged Ovariectomized Mice Bearing 4T1 Mammary Gland Cancer

(1) Background: Vitamin D compounds (VDC) are extensively studied in the field of anticancer properties, including breast cancer. Previously, we showed that calcitriol and its analogs (PRI-2191 and PRI-2205) stimulate metastasis in 4T1 murine mammary gland cancer models in young mice, whereas the reverse effect was observed in aged ovariectomized (OVX) mice; (2) Methods: We determined the phenotype of monocytes/macrophages using FACS and examined the expression of selected genes and proteins by Real-Time PCR and ELISA; (3) Results: Activities of VDC are accompanied by an increase in the percentage of Ly6Clow anti-inflammatory monocytes in the spleen of young and a decrease in aged OVX mice. Treatment of young mice with VDC resulted in an increase of CCL2 plasma and tumor concentration and Arg1 in tumor. In later stage of tumor progression the expression of genes related to metastasis in lung tissue was decreased or increased, in old OVX or young mice, respectively; (4) Conclusions: Pro- or anti-metastatic effects of calcitriol and its analogs in young or aged OVX mice, respectively, can be attributed to the differences in the effects of VDC on the tumor microenvironment, as a consequence of differences in the immunity status of young and aged mice.

Efficacy of Emu Oil Transfersomes for Local Transdermal Delivery of 4-OH Tamoxifen in the Treatment of Breast Cancer

Oral tamoxifen used in the prevention and treatment of ductal carcinoma in situ (DCIS) (estrogen-positive) patients has limited acceptance, due to its adverse side effects. The efficacy of tamoxifen is related to its major metabolite, 4-hydroxytamoxifen. Local transdermal therapy of 4-hydroxytamoxifen to the breast might avert the toxicity of oral tamoxifen, while maintaining efficacy. We aim to study the skin irritancy, as well as to evaluate the efficacy of the developed transfersome formulations, with/without emu oil, using a syngeneic mouse model of breast cancer. We also quantified tamoxifen/4-hydroxytamoxifen concentrations in blood plasma and performed histopathology. The skin irritancy test showed that the pure emu oil and transfersome formulations with or without the emu oil did not cause skin irritancy in the animals studied. A sensitive and specific LC–MS/MS method for the quantification of tamoxifen and 4-hydroxytamoxifen was developed and validated. Studies on tumor volume and necrosis (histopathology) using the breast cancer mouse model showed that the 4-OHT transfersomal formulations, with and without emu oil, showed comparable efficacy with that of orally administered tamoxifen. However, the transfersomal formulations, with and without emu oil, resulted in significantly lower (10.24 ± 0.07 and 32.45 ± 0.48 ng/mL, respectively) plasma concentrations of 4-hydroxytamoxifen, compared to the oral tamoxifen (TAMX) group (634.42 ± 7.54 ng/mL). This study demonstrated the potential use of emu oil in a local transdermal formulation for the treatment of breast cancer and its reduced adverse effects.

Ablation of Stromal Cells with a Targeted Proapoptotic Peptide Suppresses Cancer Chemotherapy Resistance and Metastasis

Adipose stromal cells (ASCs) recruited by tumors contribute to the population of cancer-associated fibroblasts. ASCs have been reported to induce tumor growth and chemotherapy resistance. The effect of ASCs on metastasis has not been explored. Here, we investigated the role of ASCs in cancer aggressiveness and tested them as a therapy target. We show that ASCs promote the epithelial-mesenchymal transition and invasiveness of triple-negative breast cancer cells. In human cell lines derived from various types of breast tumors, ASCs suppressed cytotoxicity of cisplatin and paclitaxel. D-CAN, a proapoptotic peptide targeting ASC, suppressed spontaneous breast cancer lung metastases in a mouse allograft model when combined with cisplatin. Moreover, in a human breast cancer xenograft model, treatment with D-CAN alone was sufficient to suppress lung metastases. This study improves our understanding of how tumor stromal cells recruited from fat tissue stimulate carcinoma progression to chemotherapy resistance/metastasis and outlines a new approach to combination cancer treatment.

Potentiating Antitumor Efficacy Through Radiation and Sustained Intratumoral Delivery of Anti-CD40 and Anti-PDL1

PURPOSE

Mounting evidence demonstrates that combining radiation therapy (RT) with immunotherapy can reduce tumor burden in a subset of patients. However, conventional systemic delivery of immunotherapeutics is often associated with significant adverse effects, which force treatment cessation. The aim of this study was to investigate a minimally invasive therapeutics delivery approach to improve clinical response while attenuating toxicity.

METHODS AND MATERIALS

We used a nanofluidic drug-eluting seed (NDES) for sustained intratumoral delivery of combinational antibodies CD40 and PDL1. To enhance immune and tumor response, we combined the NDES intratumoral platform with RT to treat the 4T1 murine model of advanced triple negative breast cancer. We compared the efficacy of NDES against intraperitoneal administration, which mimics conventional systemic treatment. Tumor growth was recorded, and local and systemic immune responses were assessed via imaging mass cytometry and flow cytometry. Livers and lungs were histologically analyzed for evaluation of toxicity and metastasis, respectively.

RESULTS

The combination of RT and sustained intratumoral immunotherapy delivery of CD40 and PDL1 via NDES (NDES CD40/PDL1) showed an increase in both local and systemic immune response. In combination with RT, NDES CD40/PDL1 achieved significant tumor burden reduction and liver inflammation mitigation compared with systemic treatment. Importantly, our treatment strategy boosted the abscopal effect toward attenuating lung metastatic burden.

CONCLUSIONS

Overall, our study demonstrated superior efficacy of combination treatment with RT and sustained intratumoral immunotherapy via NDES, offering promise for improving therapeutic index and clinical response.

Rationalized inhibition of mixed lineage kinase 3 and CD70 enhances life span and antitumor efficacy of CD8+ T cells

BACKGROUND

The mitogen-activated protein kinases (MAPKs) are important for T cell survival and their effector function. Mixed lineage kinase 3 (MLK3) (MAP3K11) is an upstream regulator of MAP kinases and emerging as a potential candidate for targeted cancer therapy; yet, its role in T cell survival and effector function is not known.

METHODS

T cell phenotypes, apoptosis and intracellular cytokine expressions were analyzed by flow cytometry. The apoptosis-associated gene expressions in CD8+CD38+ T cells were measured using RT2 PCR array. In vivo effect of combined blockade of MLK3 and CD70 was analyzed in 4T1 tumor model in immunocompetent mice. The serum level of tumor necrosis factor-α (TNFα) was quantified by enzyme-linked immunosorbent assay.

RESULTS

We report that genetic loss or pharmacological inhibition of MLK3 induces CD70-TNFα-TNFRSF1a axis-mediated apoptosis in CD8+ T cells. The genetic loss of MLK3 decreases CD8+ T cell population, whereas CD4+ T cells are partially increased under basal condition. Moreover, the loss of MLK3 induces CD70-mediated apoptosis in CD8+ T cells but not in CD4+ T cells. Among the activated CD8+ T cell phenotypes, CD8+CD38+ T cell population shows more than five fold increase in apoptosis due to loss of MLK3, and the expression of TNFRSF1a is significantly higher in CD8+CD38+ T cells. In addition, we observed that CD70 is an upstream regulator of TNFα-TNFRSF1a axis and necessary for induction of apoptosis in CD8+ T cells. Importantly, blockade of CD70 attenuates apoptosis and enhances effector function of CD8+ T cells from MLK3-/- mice. In immune-competent breast cancer mouse model, pharmacological inhibition of MLK3 along with CD70 increased tumor infiltration of cytotoxic CD8+ T cells, leading to reduction in tumor burden largely via mitochondrial apoptosis.

CONCLUSION

Together, these results demonstrate that MLK3 plays an important role in CD8+ T cell survival and effector function and MLK3-CD70 axis could serve as a potential target in cancer.

High-throughput single-cell analysis of exosome mediated dual drug delivery, in vivo fate and synergistic tumor therapy

Exosomes could serve as delivery platforms, owing to their good biocompatibility, stability, and long blood circulation time. Tracking the biological fate of exosomes in vivo is essential for evaluating their functions, delivery efficacy, and biosafety, and it is invaluable for guiding exosome-based therapy. Here, we merged a single-cell technique, mass cytometry, with in vivo uptake analysis to comprehensively reveal the fate of exosomes at the single-cell level. In tandem with multivariate cellular phenotyping, in vivo uptake of exosomes labeled with heavy metal-containing tags was quantified in a high-throughput manner. Interestingly, an organ-dependent uptake landscape of exosomes by diverse cell types was distinctly demonstrated, which implied that cancer cells seemed to preferably take up more released drugs from the exosomes. Using these cellular insights, the administration method of drug-loaded exosomes was optimized to elevate their accumulation in tumor sites and minimize their spread into healthy organs. Dual drug-loaded exosomes were locally administered and superior synergistic tumor treatment effects were achieved in a solid tumor model. The disclosure of exosome cellular distribution, together with the successful engineering of exosomes with multiple anticancer capacities, provides a new level of insight into optimizing and enhancing exosome-based drug delivery and synergistic tumor therapy.

Targeting of antitumor ımmune responses with live-attenuated Leishmania strains in breast cancer model

BACKGROUND

Cancer is a major cause of death worldwide and most of the therapeutic approaches are relatively ineffective in eliminating cancer especially due to drug resistance. As an alternative, therapy with live microorganisms can induce a robust proinflammatory and anti-cancer immune response in the microenvironment of the tumor. In the present study, we aimed to establish a model for taking the advantages of immune responses against intracellular protozoan parasites for cancer treatment.

METHODS

Leishmania infantum and L. tropica were used in our study as agents of visceral and cutaneous forms of the infection, respectively. After establishing 4T1 breast cancer in mice groups, live-attenuated L. infantum (At-Li) and live-attenuated L. tropica (At-Lt) treatments were performed and results were evaluated according to tumor volume, immune markers and histological examination.

RESULTS

Live-attenuated Leishmania strains regressed 4T1-breast cancer in mice and are nonpathogenic, and these strains induce an immune response against 4T1 breast cancer. It is shown that At-Lt is found to be more effective than At-Li in breast cancer treatment using different methods included in the study as analyses of immune parameters, and histopathological examination in tumor tissue besides spleen cells. The tumor grew more slowly by the immune-stimulant effect of live-attenuated Leishmania parasites.

CONCLUSION

This promising therapy should be investigated for optimization in further studies with different cancer types and L. tropica may be designed to express antigens to enhance tumor antigen-specific responses, which may further improve efficacy and immune memory development.

Mechanisms of site-specific dephosphorylation and kinase opposition imposed by PP2A regulatory subunits

PP2A is an essential protein phosphatase that regulates most cellular processes through the formation of holoenzymes containing distinct regulatory B‐subunits. Only a limited number of PP2A‐regulated phosphorylation sites are known. This hampers our understanding of the mechanisms of site‐specific dephosphorylation and of its tumor suppressor functions. Here, we develop phosphoproteomic strategies for global substrate identification of PP2A‐B56 and PP2A‐B55 holoenzymes. Strikingly, we find that B‐subunits directly affect the dephosphorylation site preference of the PP2A catalytic subunit, resulting in unique patterns of kinase opposition. For PP2A‐B56, these patterns are further modulated by affinity and position of B56 binding motifs. Our screens identify phosphorylation sites in the cancer target ADAM17 that are regulated through a conserved B56 binding site. Binding of PP2A‐B56 to ADAM17 protease decreases growth factor signaling and tumor development in mice. This work provides a roadmap for the identification of phosphatase substrates and reveals unexpected mechanisms governing PP2A dephosphorylation site specificity and tumor suppressor function.

Retinol-Binding Protein 4 Accelerates Metastatic Spread and Increases Impairment of Blood Flow in Mouse Mammary Gland Tumors

Retinol-binding protein 4 (RBP4) is proposed as an adipokine that links obesity and cancer. We analyzed the role of RBP4 in metastasis of breast cancer in patients and in mice bearing metastatic 4T1 and nonmetastatic 67NR mammary gland cancer. We compared the metastatic and angiogenic potential of these cells transduced with Rbp4 (4T1/RBP4 and 67NR/RBP4 cell lines). Higher plasma levels of RBP4 were observed in breast cancer patients with metastatic tumors than in healthy donors and patients with nonmetastatic cancer. Increased levels of RBP4 were observed in plasma, tumor tissue, liver, and abdominal fat. Moreover, the blood vessel network was highly impaired in mice bearing 4T1 as compared to 67NR tumors. RBP4 transductants showed further impairment of blood flow and increased metastatic potential. Exogenous RBP4 increased lung settlement by 67NR and 4T1 cells. In vitro studies showed increased invasive and clonogenic potential of cancer cells treated with or overexpressing RBP4. This effect is not dependent on STAT3 phosphorylation. RBP4 enhances the metastatic potential of breast cancer tumors through a direct effect on cancer cells and through increased endothelial dysfunction and impairment of blood vessels within the tumor.

Neutrophil-mediated transport is crucial for delivery of short-circulating magnetic nanoparticles to tumors

Recently neutrophil-based nanoparticles (NPs) drug delivery systems have gained considerable attention in cancer therapy. Numerous studies have been conducted to identify optimal NPs parameters for passive tumor targeting, while there is a fundamental dearth of knowledge about the factors governing cell-mediated delivery. Here, by using intravital microscopy and magnetic resonance imaging, we describe accumulation dynamics of 140 nm magnetic cubes and clusters in murine breast cancer (4T1) and colon cancer (CT26) models. Notwithstanding rapid clearance from the blood flow, NPs readily accumulated in tumors at later time points. Both NPs types were captured mostly by intravascular neutrophils immediately after injection, and transmigration of NPs-bound neutrophils through the vessel wall was first shown in real-time. A dramatic drop in NPs accumulation upon Ly6G and Gr1 depletion further confirmed the role of neutrophils as a biocarrier for targeting tumors. Of note, for shorter circulating NPs, a cell-dependent delivery route was more impactful, while the accumulation of longer circulating counterpart was less compromised by neutrophil depletion. Neutrophil-mediated transport was also shown to depend on tumor type, with more efficiency noted in neutrophil-rich tumors. Revealing NPs characteristics and host factors influencing the neutrophil-based tumor targeting will help to rationally design drug delivery systems for improved cancer treatment. STATEMENT OF SIGNIFICANCE: Utilizing host cells as trojan horses for delivery nanodrugs to tumor site is a promising approach for cancer therapy. However, it is not clear yet how nanoparticles characteristics and tumor properties affect the efficiency of cell-based nanoparticles transport. Here, we compare neutrophil-based delivery of different-shaped magnetic nanoparticles (cubes and clusters) in two tumor models. The results suggest that neutrophil-mediated route is more impactful for rapidly cleared cubes, than for longer circulating clusters. The efficiency of cell-based accumulation also correlated with the level of neutrophils recruitment to different tumor types. These finding are important for rationale design of nanocarriers and predicting the efficiency of neutrophil-mediated drug delivery between patients and tumor types.

Temperature-controlled magnetic nanoparticles hyperthermia inhibits primary tumor growth and metastases dissemination

Magnetic hyperthermia (MHT) is a promising approach for cancer therapy. However, a systematic MHT characterization as function of temperature on the therapeutic efficiency is barely analyzed. Here, we first perform comparative temperature-dependent analysis of the cobalt ferrite nanoparticles-mediated MHT effectiveness in two murine tumors models - breast (4T1) and colon (CT26) cancer in vitro and in vivo. The overall MHT killing capacity in vitro increased with the temperature and CT26 cells were more sensitive than 4T1 when heated to 43 °C. Well in line with the in vitro data, such heating cured non-metastatic CT26 tumors in vivo, while only inhibiting metastatic 4T1 tumor growth without improving the overall survival. High-temperature MHT (>47 °C) resulted in complete 4T1 primary tumor clearance, 25-40% long-term survival rates, and, importantly, more effective prevention of metastasis comparing to surgical extraction. Thus, the specific MHT temperature must be defined for each tumor individually to ensure a successful antitumor therapy.

20(S)-Protopanaxdiol Suppresses the Abnormal Granule-Monocyte Differentiation of Hematopoietic Stem Cells in 4T1 Breast Cancer-Bearing Mouse

Panax notoginseng (PN) has been used as a qi- and blood-activating (Huoxue) drug for thousands of years in China. It has also been widely used as an anticancer drug at present. As a Huoxue drug, the effect of PN on hematopoietic differentiation in tumor-bearing body has been paid more and more attention. Our research found that panax notoginseng saponins (PNS), especially panaxadiol saponins (PDS) and its aglucon 20(S)-Protopanaxdiol (PPD), could improve the immunosuppressive state by regulating the abnormal hematopoietic differentiation in a tumor-bearing body by multiple ways. An interesting phenomenon is that PDS reduced the neutrophil-lymphocyte ratio (NLR) via its inhibition effect on the granule-monocyte differentiation of spleen cells, which is associated with a decrease in the secretion of tumor MPO, G-CSF, PU.1, and C/EBPα. Otherwise, PDS increased the proportion of both hematopoietic stem cells and erythroid progenitor cells in the bone marrow, but inhibited spleen erythroid differentiation via inhibiting secretion of tumor EPO, GATA-1, and GATA-2. This study suggests that PNS regulated the tumor-induced abnormal granule-monocyte differentiation of hematopoietic stem cells, affecting the distribution and function of haemocytes in tumor-bearing mice.

Effects Induced In Vivo by Exposure to Magnetic Signals Derived From a Healing Technique

Energy healing is a therapy said to manipulate and balance the flow of "energies" in the body. One such technique, the Bengston Healing Method (BHM), has shown some success in healing malignant tumors in animals and humans, but the mechanism of action and factors influencing therapeutic success of this method are poorly understood. In this study, we tested in vivo the antitumor potential of magnetic signals recorded during BHM healing. Balb/c mice engrafted with 4T1 breast cancer cells were exposed to this recording for 4 h/d on a weekly or daily basis for 28 days; control mice were not exposed at all. Tumors showed a trend to grow slower in the treatment versus control group during the fourth week of treatment. Elevated leukocyte counts, associated with an increase in blood levels of granulocyte-macrophage colony stimulating factor and interleukin-6, were observed in tumor-bearing mice exposed to the BHM recording but not in healthy animals exposed to the recording. This suggests that exposure to a recording of BHM may induce a biological response in tumor-bearing mice, but limited effects on tumor growth when observed within the predefined end point of 28 days. Studies involving longer end points are recommended to observe the progression of tumor growth.

Neutrophils and neutrophil extracellular traps enhance venous thrombosis in mice bearing human pancreatic tumors

Pancreatic cancer is associated with a high incidence of venous thromboembolism. Neutrophils have been shown to contribute to thrombosis in part by releasing neutrophil extracellular traps (NET). A recent study showed that increased plasma levels of the NET biomarker, citrullinated histone H3 (H3Cit), are associated with venous thromboembolism in patients with pancreatic and lung cancer but not in those with other types of cancer, including breast cancer. In this study, we examined the contribution of neutrophils and NET to venous thrombosis in nude mice bearing human pancreatic tumors. We found that tumor-bearing mice had increased circulating neutrophil counts and levels of granulocyte-colony stimulating factor, neutrophil elastase, H3Cit and cell-free DNA compared with controls. In addition, thrombi from tumor-bearing mice contained increased levels of the neutrophil marker Ly6G, as well as higher levels of H3Cit and cell-free DNA. Thrombi from tumor-bearing mice also had denser fibrin with thinner fibers consistent with increased thrombin generation. Importantly, either neutrophil depletion or administration of DNase I reduced the thrombus size in tumor-bearing but not in control mice. Our results, together with clinical data, suggest that neutrophils and NET contribute to venous thrombosis in patients with pancreatic cancer.

Cancer Cell-Derived Granulocyte-Macrophage Colony-Stimulating Factor Is Dispensable for the Progression of 4T1 Murine Breast Cancer

We previously reported that 4T1 murine breast cancer cells produce GM-CSF that up-regulates macrophage expression of several cancer promoting genes, including Mcp-1/Ccl2, Ccl17 and Rankl, suggesting a critical role of cancer cell-derived GM-CSF in cancer progression. Here, we attempted to define whether 4T1 cell-derived GM-CSF contributes to the expression of these genes by 4T1tumors, and their subsequent progression. Intraperitoneal injection of anti-GM-CSF neutralizing antibody did not decrease the expression of Mcp-1, Ccl17 or Rankl mRNA by 4T1 tumors. To further examine the role of cancer cell-derived GM-CSF, we generated GM-CSF-deficient 4T1 cells by using the Crisper-Cas9 system. As previously demonstrated, 4T1 cells are a mixture of cells and cloning of cells by itself significantly reduced tumor growth and lung metastasis. By contrast, GM-CSF-deficiency did not affect tumor growth, lung metastasis or the expression of these chemokine and cytokine genes in tumor tissues. By in-situ hybridization, the expression of Mcp-1 mRNA was detected in both F4/80-expressing and non-expressing cells in tumors of GM-CSF-deficient cells. These results indicate that cancer cell-derived GM-CSF is dispensable for the tuning of the 4T1 tumor microenvironment and the production of MCP-1, CCL17 or RANKL in the 4T1 tumor microenvironment is likely regulated by redundant mechanisms.

Peptide-Targeted Polyplexes for Aerosol-Mediated Gene Delivery to CD49f-Overexpressing Tumor Lesions in Lung

Peptide ligands can enhance delivery of nucleic acid-loaded nanoparticles to tumors by promoting their cell binding and internalization. Lung tumor lesions accessible from the alveolar side can be transfected, in principle, using gene vectors delivered as an aerosol. The cell surface marker CD49f (Integrin α6) is frequently upregulated in metastasizing, highly aggressive tumors. In this study, we utilize a CD49f binding peptide coupled to linear polyethylenimine (LPEI) promoting gene delivery into CD49f-overexpressing tumor cells in vitro and into lung lesions in vivo. We have synthesized a molecular conjugate based on LPEI covalently attached to the CD49f binding peptide CYESIKVAVS via a polyethylene glycol (PEG) spacer. Particles formed with plasmid DNA were small (<200 nm) and could be aerosolized without causing major aggregation or particle loss. In vitro, CD49f targeting significantly improved plasmid uptake and reporter gene expression on both human and murine tumor cell lines. For evaluation in vivo, localization and morphology of 4T1 murine triple-negative breast cancer tumor lesions in the lung of syngeneic BALB/c mice were identified by MRI. Polyplexes applied via intratracheal aerosolization were well tolerated and resulted in measurable transgene activity of the reporter gene firefly luciferase in tumor areas by bioluminescence imaging (BLI). Transfectability of tumors correlated with their accessibility for the aerosol. With CD49f-targeted polyplexes, luciferase activity was considerably increased and was restricted to the tumor area.

Jatrorrhizine inhibits mammary carcinoma cells by targeting TNIK mediated Wnt/β-catenin signalling and epithelial-mesenchymal transition (EMT)

BACKGROUND

Traf2 and Nck interacting serine protein kinase (TNIK) is a tumour target protein which its high expression is closely related to the occurrence and development of mammary carcinoma cells. Molecular docking revealed that jatrorrhizine, a protoberberine alkaloid, exhibits good binding affinity and interaction with TNIK. However, the underlying mechanisms of jatrorrhizine targeting TNIK inhibits the proliferation and metastasis of breast cancer cells remain unclear.

METHODS

To figure out the mechanisms in vitro and in vivo, the CRISPR/Cas9 technology was used to knockout TNIK gene and detected qualitatively by immunofluorescence and immunoblotting assay. The MTT cell viability assay for cytotoxicity test, the apoptosis were detected by flow cytometry, the migration and invasion were evaluated by colony formation, wound healing assay and cell invasion assay, respectively. Anticancer effects were further corroborated by 4T1/Luc homograft tumour model.

RESULTS

The results showed that targeted knockout of TNIK that attenuated Wnt/β-catenin signalling and epithelial-mesenchymal transition (EMT) expression, the effects were potentiated by the addition of jatrorrhizine. Moreover, jatrorrhizine distinctly inhibited the proliferation of MDA-MB-231, MCF-7 and 4T1 cells with IC₅₀ values of 11.08 ± 1.19 μM, 17.11 ± 4.54 μM and 22.14 ± 2.87 μM, induced mitochondrial dysfunction and early apoptosis involving mitochondrial apoptotic pathway. These results were further corroborated by the 4T1 tumour-bearing mice, which showed that jatrorrhizine significantly suppressed the proliferation and metastasis of mammary carcinoma cells without obvious toxicity.

CONCLUSION

These findings provide an overall perspective that jatrorrhizine potentially restrains TNIK regulating Wnt/β-catenin signalling and EMT expression for mammary cancer targeted therapy.

Recruitment of monocytes and epigenetic silencing of intratumoral CYP7B1 primarily contribute to the accumulation of 27-hydroxycholesterol in breast cancer

Previous studies showed that intratumoral 27-Hydroxycholesterol (27-HC), a metabolite of cholesterol, promotes growth, invasion and migration of breast cancer cells and that tumor-associated macrophages (TAMs) in breast cancers are closely related to tumor growth and metastatic progression. However, the relationship between 27-HC and TAMs in breast cancer remains unclear. In the present study, we observed that CYP27A1, the 27-HC synthesizing enzyme, was expressed in a much higher level in THP1 monocytes and THP1-derived macrophages than in breast cancer cells, and the promoter of CYP7B1, the degrading enzyme for 27-HC, was highly methylated in breast tumor cells. In addition, THP-1 monocytes and murine bone marrow cells were differentiated toward M2 type macrophages after being co-cultured with breast cancer cells or being exposed to exosomes derived from breast cancer cells. M2 type macrophages produced higher amounts of 27-HC than M0 and M1 type macrophages. 27-HC not only stimulated ER+ cancer cell proliferation as reported, but also promoted the recruitment of CCR2- and CCR5-expressing monocytes by inducing macrophages to express multiple chemokines including CCL2, CCL3 and CCL4. Taken together, our data demonstrate that the hypermethylation of CYP7B1 and recruitment of monocytes likely contribute to the accumulation of 27-Hydroxycholesterol in breast cancer and that the interaction of 27-HC with macrophages further promote the development of breast cancer.

A transplantable tumor model allowing investigation of NY-BR-1-specific T cell responses in HLA-DRB1*0401 transgenic mice

BACKGROUND

NY-BR-1 has been described as a breast cancer associated differentiation antigen with intrinsic immunogenicity giving rise to endogenous T and B cell responses. The current study presents the first murine tumor model allowing functional investigation of NY-BR-1-specific immune responses in vivo.

METHODS

A NY-BR-1 expressing tumor model was established in DR4tg mice based on heterotopic transplantation of stable transfectant clones derived from the murine H2 compatible breast cancer cell line EO771. Composition and phenotype of tumor infiltrating immune cells were analyzed by qPCR and FACS. MHC I binding affinity of candidate CTL epitopes predicted in silico was determined by FACS using the mutant cell line RMA-S. Frequencies of NY-BR-1 specific CTLs among splenocytes of immunized mice were quantified by FACS with an epitope loaded D^b-dextramer. Functional CTL activity was determined by IFNγ catch or IFNγ ELISpot assays and statistical analysis was done applying the Mann Whitney test. Tumor protection experiments were performed by immunization of DR4tg mice with replication deficient recombinant adenovirus followed by s.c. challenge with NY-BR-1 expressing breast cancer cells.

RESULTS

Our results show spontaneous accumulation of CD8⁺ T cells and F4/80⁺ myeloid cells preferentially in NY-BR-1 expressing tumors. Upon NY-BR-1-specific immunization experiments combined with in silico prediction and in vitro binding assays, the first NY-BR-1-specific H2-D^b-restricted T cell epitope could be identified. Consequently, flow cytometric analysis with fluorochrome conjugated multimers showed enhanced frequencies of CD8⁺ T cells specific for the newly identified epitope in spleens of immunized mice. Moreover, immunization with Ad.NY-BR-1 resulted in partial protection against outgrowth of NY-BR-1 expressing tumors and promoted intratumoral accumulation of macrophages.

CONCLUSION

This study introduces the first H2-D^b-resctricted CD8⁺ T cell epitope-specific for the human breast cancer associated tumor antigen NY-BR-1. Our novel, partially humanized tumor model enables investigation of the interplay between HLA-DR4-restricted T cell responses and CTLs within their joint attack of NY-BR-1 expressing tumors.

Targeting myeloid-derived suppressor cells in combination with primary mammary tumor resection reduces metastatic growth in the lungs

BACKGROUND

Solid tumors produce proteins that can induce the accumulation of bone marrow-derived cells in various tissues, and these cells can enhance metastatic tumor growth by several mechanisms. 4T1 murine mammary tumors are known to produce granulocyte colony-stimulating factor (G-CSF) and increase the numbers of immunosuppressive CD11b⁺Gr1⁺ myeloid-derived suppressor cells (MDSCs) in tissues such as the spleen and lungs of tumor-bearing mice. While surgical resection of primary tumors decreases MDSC levels in the spleen, the longevity and impact of MDSCs and other immune cells in the lungs after tumor resection have been less studied.

METHODS

We used mass cytometry time of flight (CyTOF) and flow cytometry to quantify MDSCs in the spleen, peripheral blood, and lungs of mice bearing orthotopic murine mammary tumors. We also tested the effect of primary tumor resection and/or gemcitabine treatment on the levels of MDSCs, other immune suppressor and effector cells, and metastatic tumor cells in the lungs.

RESULTS

We have found that, similar to mice with 4T1 tumors, mice bearing metastatic 4T07 tumors also exhibit accumulation of CD11b⁺Gr1⁺ MDSCs in the spleen and lungs, while tissues of mice with non-metastatic 67NR tumors do not contain MDSCs. Mice with orthotopically implanted 4T1 tumors have increased granulocytic (G-) MDSCs, monocytic (M-) MDSCs, macrophages, eosinophils, and NK cells in the lungs. Resection of primary 4T1 tumors decreases G-MDSCs, M-MDSCs, and macrophages in the lungs within 48 h, but significant numbers of functional immunosuppressive G-MDSCs persist in the lungs for 2 weeks after tumor resection, indicative of an environment that can promote metastatic tumor growth. The chemotherapeutic agent gemcitabine depletes G-MDSCs, M-MDSCs, macrophages, and eosinophils in the lungs of 4T1 tumor-bearing mice, and we found that treating mice with gemcitabine after primary tumor resection decreases residual G-MDSCs in the lungs and decreases subsequent metastatic growth.

CONCLUSIONS

Our data support the development of therapeutic strategies to target MDSCs and to monitor MDSC levels before and after primary tumor resection to enhance the effectiveness of immune-based therapies and improve the treatment of metastatic breast cancer in the clinic.

β-2-Himachalen-6-ol inhibits 4T1 cells-induced metastatic triple negative breast carcinoma in murine model

β-2-himachalen-6-ol (HC), a major sesquiterpene isolated from the Lebanese wild carrot umbels, was shown to possess remarkable in vitro and in vivo anticancer activities. The present study investigates the anti-metastatic activity of HC post 4T1 breast cancer cells inoculation in a murine model. The effect of HC on 4T1 cell viability was assessed using WST-1 kit, while cell cycle analysis was performed using flow cytometry. Tumor development and metastasis were evaluated by injecting 4T1 cells in the mice mammary gland region followed by either HC or cisplatin treatment. The 6-thioguanine assay was used for the quantification of metastatic cells in the blood. HC treatment caused a dose-dependent decrease in cell viability with IC₅₀ and IC₉₀ values of 7 and 28 μg/mL respectively. Concomitant treatment with cisplatin significantly reduced cell viability when compared to cells treated with cisplatin or HC alone. Flow cytometry revealed a significant increase (p˂0.05) in cell count in the Sub-G1 phase at HC 10 μg/mL, and total DNA fragmentation (p˂0.001) at HC 25 μg/mL. Annexin/PI staining showed early and late apoptotic mode of cell death upon treatment with HC. Histopathological evaluation revealed less incidence of primary and metastatic tumor/inflammation in the HC and cisplatin treated groups. Tumor size and colony-forming units were significantly decreased in the HC treated group. HC treatment induced cell cycle arrest, promoted apoptosis and reduced the incidence of primary and metastatic lesions caused by 4T1 cells. The present findings suggest that HC has an anti-metastatic potential against aggressive types of cancer.

Cowpea Mosaic Virus Immunotherapy Combined with Cyclophosphamide Reduces Breast Cancer Tumor Burden and Inhibits Lung Metastasis

Patients with metastatic triple-negative breast cancer (TNBC) have a poor prognosis, so new therapies or drug combinations that achieve more effective and durable responses are urgently needed. Here, a combination therapy using cowpea mosaic virus (CPMV) and low doses of cyclophosphamide (CPA) is developed with remarkable synergistic efficacy against 4T1 mouse tumors in vivo. The combination therapy not only attenuates the growth of primary tumor and increases survival, but also suppresses distant tumor growth and reduces lung metastasis. Mechanistic analysis indicates that the combination of CPMV and CPA increases the secretion of several cytokines, activates antigen-presenting cells, increases the abundance of tumor infiltrating T cells, and systematically reverses the immunosuppression. These results show that the combination of CPMV in situ vaccination with chemotherapy may become a potent new strategy for the treatment of TNBC.

Folate-coated, long-circulating and pH-sensitive liposomes enhance doxorubicin antitumor effect in a breast cancer animal model

Long circulating pH-sensitive liposomes have been shown to effectively deliver doxorubicin (DOX) to tumors and reduce its toxic effects. Folic acid receptors are upregulated in a wide variety of solid, epithelial tumors, including breast cancer. In order to improve liposomal endocytosis and antitumor activity, folic acid has been added to nanoparticles surfaces to exploit overexpression of folate receptors in tumor cells. The purpose of this study was to evaluate the antitumor activity in vitro and in vivo of long circulating pH-sensitive folate-coated DOX-loaded liposomes (SpHL-DOX-Fol) in a 4T1 breast cancer model system in vitro and in vivo. Biodistribution studies were performed and in vivo electrocardiographic parameters were evaluated. A higher tumor uptake for radiolabeled SpHL-Fol (^99mTc-SpHL-Fol) 4 h after intravenous administration was observed in comparision with non-folate-coated liposomes (^99mTc-SpHL). Antitumor activity showed that SpHL-DOX-Fol treatment led to a 68% growth arrest and drastically reduce pulmonary metastasis foci. Additionally, eletrocardiographic parameters analysis revealed no dispersion in the QT and QTc interval was observed in liposomal treated mice. In summary, this novel multifunctional nanoplatform deomonstrated higher tumor uptake and antitumor activity. SpHL-DOX-Fol represents a drug delivery platform to improve DOX tumor delivery and reduce dose-limiting toxicity.

Dimeric c(RGD) peptide conjugated nanostructured lipid carriers for efficient delivery of Gambogic acid to breast cancer

Background and purpose: Gambogic acid (GA) is a natural compound that exhibited a promising multi-target antitumor activity against several types of cancer. However, the clinical application of this drug is limited due to its poor solubility and low tumor cell-specific delivery. In this study, the monomeric and dimeric Cyclo (Arg-Gly-Asp) c(RGD) tumor targeting peptides (c(RGDfK) and E-[c(RGDfK)2]) were used to modify GA loaded nanostructured lipid carriers (NLC) to reduce the limitations associated with GA and improve its antitumor activity. Methods: GA-NLC was prepared by emulsification and solvent evaporation methods and the surface of the NLC was conjugated with the c(RGD) peptides via an amide bond. The formulations were characterized for particle size, morphology and zeta potential, encapsulation efficiency and drug loading. The in-vitro cytotoxicity and cell uptake studies were conducted using 4T1 cell. Furthermore, the in-vivo antitumor activity and bio-distribution study were performed on female BALB/c nude mice. Results: The c(RGD) peptides modified GA-NLC was successfully prepared with the particles size about 20 nm. The HPLC analysis, FT-IR and 1H-NMR spectra confirmed the successful conjugation of the peptides with the NLC. The in-vitro cytotoxicity study on 4T1 cells revealed that c(RGD) peptides modified GA-NLCs showed significantly higher cytotoxicity at 0.25 and 0.5 µg/mL as compared to unmodified GA-NLC. Furthermore, the cell uptake study demonstrated that better accumulation of E-[c(RGDfK)2] peptides modified NLC in 4T1 cell after 12 h incubation. Moreover, the in-vivo study showed that c(RGD)s functionalized GA-NLC exhibited better accumulation in tumor tissue and tumor growth inhibition. In contrast to the monomeric c(RGD) peptide, the dimeric c(RGD) peptide (E-[c(RGDfK)2]) conjugated GA-NLC showed the improved antitumor activity and tumor targeting ability of GA-NLC. Conclusion: These data provide further support for the potential clinical applications of E-[c(RGDfK)2]-GA-NLC in breast cancer therapy.

Evaluation of Local Injection of Bevacizumab against Triple-Negative Breast Cancer Xenograft Tumors

Background and objective:

Bevacizumab (BVZ) is a recombinant humanized antibody that inhibits the vascular endothelial growth factor A (VEGFA) and is used for the treatment of various types of cancer. BVZ is primarily given by the intravenous drip (I.V.), which often leads to low efficacy and various side effects. Therefore, the present study was to evaluate the effect of local delivery of BVZ against triple-negative breast cancer (TNBC) xenograft tumors.

Methods:

Mice 4T1 TNBC cells were engrafted in female BALB/c mice. After the tumors reached about 5 mm (diameter), animals were treated with BVZ through the local injection from four directions around the tumors. The tumor growth, survival and potential mechanisms of action were evaluated.

Results:

The growth and microvessel density of engrafted tumors were dramatically reduced with the tumor inhibition rate of 32.8 ± 3%. No obvious side effects were observed. The expression of VEGFA, VEGF receptor (VEGFR), matrix metalloproteinase (MMP)-2, MMP-9, Delta-like ligand 4 (DLL4) and Integrin-5 was significantly reduced in TNBC tumor tissues. In contrast, tissue inhibitor of matrix metalloproteinase (TIMP)-2 was significantly upregulated in xenograft tumors. Additionally, local delivery of BVZ led to the reduction of VEGFA and tumor necrosis factor (TNF)-alpha in the serum. Protein-protein interaction (PPI) analysis revealed that the proteins altered by the local delivery of BVZ were associated with angiogenesis and regulation of cell migration.

Conclusion:

This study provided evidence associated with local delivery of BVZ against TNBC tumors supporting the use of BVZ local injections to overcome some of the disadvantages associated with I.V. therapy with BVZ.

Intraductal Adaptation of the 4T1 Mouse Model of Breast Cancer Reveals Effects of the Epithelial Microenvironment on Tumor Progression and Metastasis

BACKGROUND

Low success rates in oncology drug development are prompting re-evaluation of preclinical models, including orthotopic tumor engraftment. In breast cancer models, tumor cells are typically injected into mouse mammary fat pads (MFP). However, this approach bypasses the epithelial microenvironment, potentially altering tumor properties in ways that affect translational application.

MATERIALS AND METHODS

Tumors were generated by mammary intraductal (MIND) engraftment of 4T1 carcinoma cells. Growth, histopathology, and molecular features were quantified.

RESULTS

Despite growth similar to that of 4T1 MFP tumors, 4T1 MIND tumors exhibit distinct histopathology and increased metastasis. Furthermore, >6,000 transcripts were found to be uniquely up-regulated in 4T1 MIND tumor cells, including genes that drive several cancer hallmarks, in addition to two known therapeutic targets that were not up-regulated in 4T1 MFP tumor cells.

CONCLUSION

Engraftment into the epithelial microenvironment generates tumors that more closely recapitulate the complexity of malignancy, suggesting that intraductal adaptation of orthotopic mammary models may be an important step towards improving outcomes in preclinical drug screening and development.

Magnetophoretic Delivery of a Tumor-Priming Agent for Chemotherapy of Metastatic Murine Breast Cancer

Tumor microenvironment is a significant physical barrier to the effective delivery of chemotherapy into solid tumors. To overcome this challenge, tumors are pretreated with an agent that reduces cellular and extracellular matrix densities prior to chemotherapy. However, it also comes with a concern that metastasis may increase due to the loss of protective containment. We hypothesize that timely priming at the early stage of primary tumors will help control metastasis. To test this, we primed orthotopic 4T1 breast tumors with a paclitaxel (PTX)-loaded iron-oxide-decorated poly(lactic- co-glycolic acid) nanoparticle (NP) composite (PTX@PINC), which can be quickly concentrated in target tissues with the aid of an external magnet, and monitored its effect on the delivery of subsequently administered NPs. Magnetic resonance imaging and optical whole-body imaging confirmed that PTX@PINC was efficiently delivered to tumors by the external magnet and help loosen the tumors to accommodate subsequently delivered NPs. Consistently, the primed tumors responded to Doxil better than nonprimed tumors. In addition, lung metastasis was significantly reduced in the animals PINC-primed prior to Doxil administration. These results support that PINC combined with magnetophoresis can facilitate the timely management of primary tumors with a favorable secondary effect on metastasis.

Characterization of Cancer-Induced Nociception in a Murine Model of Breast Carcinoma

Severe and poorly treated pain often accompanies breast cancer. Thus, novel mechanisms involved in breast cancer-induced pain should be investigated. Then, it is necessary to characterize animal models that are reliable with the symptoms and progression of the disease as observed in humans. Explaining cancer-induced nociception in a murine model of breast carcinoma was the aim of this study. 4T1 (10⁴) lineage cells were inoculated in the right fourth mammary fat pad of female BALB/c mice; after this, mechanical and cold allodynia, or mouse grimace scale (MGS) were observed for 30 days. To determine the presence of bone metastasis, we performed the metastatic clonogenic test and measure calcium serum levels. At 20 days after tumor induction, the antinociceptive effect of analgesics used to relieve pain in cancer patients (acetaminophen, naproxen, codeine or morphine) or a cannabinoid agonist (WIN 55,212-2) was tested. Mice inoculated with 4T1 cells developed mechanical and cold allodynia and increased MGS. Bone metastasis was confirmed using the clonogenic assay, and hypercalcemia was observed 20 days after cells inoculation. All analgesic drugs reduced the mechanical and cold allodynia, while the MGS was decreased only by the administration of naproxen, codeine, or morphine. Also, WIN 55,212-2 improved all nociceptive measures. This pain model could be a reliable form to observe the mechanisms of breast cancer-induced pain or to observe the efficacy of novel analgesic compounds.

Selenopheno[2,3-f]coumarins: novel scaffolds with antimetastatic activity against melanoma and breast cancer

The general aim of the current research is to find novel non-toxic small molecules with antimetastatic activity.

Alterations in arginine and energy metabolism, structural and signalling lipids in metastatic breast cancer in mice detected in plasma by targeted metabolomics and lipidomics

Background

The early detection of metastasis based on biomarkers in plasma may improve cancer prognosis and guide treatment. The aim of this work was to characterize alterations in metabolites of the arginine pathway, energy metabolism, and structural and signalling lipids in plasma in the early and late stages of murine breast cancer metastasis.

Methods

Mice were orthotopically inoculated with 4T1 metastatic breast cancer cells, and plasma was analysed along the pulmonary metastasis progression using LC-MS/MS-based targeted metabolomics and lipidomics.

Results

Based on primary tumour growth and pulmonary metastases, 1–2 weeks after 4T1 cancer cell inoculation was defined as an early metastatic stage, and 3–4 weeks after 4T1 cancer cell inoculation was defined as a late metastatic stage. Early metastasis was featured in plasma by a shift of L-arginine metabolism towards arginase (increased ornithine/arginine ratio) and polyamine synthesis (increased putrescine). Late metastasis was reflected in plasma by further progression of changes in the arginine pathway with an additional increase in asymmetric dimethylarginine plasma concentration, as well as by a profound energy metabolism reprogramming towards glycolysis, an accelerated pentose phosphate pathway and a concomitant decrease in tricarboxylic cycle rate (“Warburg effect”). The late but not the early phase of metastasis was also characterized by a different lipid profile pattern in plasma, including a decrease in total phosphatidylcholines, a decrease in diester-bound phospholipid fraction and an increase in lysophospholipids associated with an increase in total sphingomyelins.

Conclusions

The early phase of metastasis in murine 4T1 metastatic breast cancer was associated with plasma metabolome changes characteristic of arginase activation and polyamine synthesis. The late metastasis was reflected in plasma not only by the alterations in arginine pathways but also by a shift towards glycolysis and the pentose pathway, remodelling of structural lipids and activation of lipid signalling, all of which coincided with metastasis progression.

Electronic supplementary material

The online version of this article (10.1186/s13058-018-1075-y) contains supplementary material, which is available to authorized users.

Investigation of the antitumor activity and toxicity of long-circulating and fusogenic liposomes co-encapsulating paclitaxel and doxorubicin in a murine breast cancer animal model

To associate paclitaxel (PTX) with doxorubicin (DXR) is one of the main chemotherapy strategies for breast cancer (BC) management. Despite the high response rates for this combination, it presents a cardiotoxic synergism, attributed to pharmacokinetic interactions between PTX and both DXR and its metabolite, doxorubicinol. One of the main strategies to minimize the cardiotoxicity of the combination is to extend the interval of time between DXR and PTX administration. However, it has been previously suggested that their co-administration leads to better efficacy compared to their sequential administration. In the present study, we investigated different molar ratio combinations of PTX:DXR (10:1; 1:1, and 1:10) against the 4T1 murine breast cancer cell line and concluded that there is no benefit of enhancing PTX concentration above that of DXR on the combination. Therefore, we obtained a long-circulating and fusogenic liposomal formulation co-encapsulating PTX and DXR (LCFL-PTX/DXR) at a molar ratio of 1:10, respectively, which maintained the in vitro biological activity of the combination. This formulation was investigated for its antitumor activity and toxicity in Balb/c mice bearing 4T1 breast tumor, and compared to treatments with free PTX, free DXR, and the mixture of free PTX:DXR at 1:10 molar ratio. The higher tumor inhibition ratios were observed for the treatments with free and co-encapsulated PTX:DXR in liposomes (66.87 and 66.52%, respectively, P>0.05) as compared to the control. The great advantage of the treatment with LCFL-PTX/DXR was its improved cardiac toxicity profile. While degeneration was observed in the hearts of all animals treated with the free PTX:DXR combination, no signs of cardiac toxicity were observed for animals treated with the LCFL-PTX/DXR. Thus, LCFL-PTX/DXR enables the co-administration of PTX and DXR, and might be considered valuable for breast cancer management.

13C Pyruvate Transport Across the Blood-Brain Barrier in Preclinical Hyperpolarised MRI

Hyperpolarised MRI with Dynamic Nuclear Polarisation overcomes the fundamental thermodynamic limitations of conventional magnetic resonance, and is translating to human studies with several early-phase clinical trials in progress including early reports that demonstrate the utility of the technique to observe lactate production in human brain cancer patients. Owing to the fundamental coupling of metabolism and tissue function, metabolic neuroimaging with hyperpolarised [1-13C]pyruvate has the potential to be revolutionary in numerous neurological disorders (e.g. brain tumour, ischemic stroke, and multiple sclerosis). Through the use of [1-13C]pyruvate and ethyl-[1-13C]pyruvate in naïve brain, a rodent model of metastasis to the brain, or porcine brain subjected to mannitol osmotic shock, we show that pyruvate transport across the blood-brain barrier of anaesthetised animals is rate-limiting. We show through use of a well-characterised rat model of brain metastasis that the appearance of hyperpolarized [1-13C]lactate production corresponds to the point of blood-brain barrier breakdown in the disease. With the more lipophilic ethyl-[1-13C]pyruvate, we observe pyruvate production endogenously throughout the entire brain and lactate production only in the region of disease. In the in vivo porcine brain we show that mannitol shock permeabilises the blood-brain barrier sufficiently for a dramatic 90-fold increase in pyruvate transport and conversion to lactate in the brain, which is otherwise not resolvable. This suggests that earlier reports of whole-brain metabolism in anaesthetised animals may be confounded by partial volume effects and not informative enough for translational studies. Issues relating to pyruvate transport and partial volume effects must therefore be considered in pre-clinical studies investigating neuro-metabolism in anaesthetised animals, and we additionally note that these same techniques may provide a distinct biomarker of blood-brain barrier permeability in future studies.

Comparison of [18F]Fluorocholine and [18F]Fluordesoxyglucose for assessment of progression, lung metastasis detection and therapy response in murine 4T1 breast tumor model

The [18F]Fluorocholine ([18F]FCH) tracer for PET imaging has been proven to be effective for several malignances. However, there are only a few studies related to its breast tumor applicability and they are still limited. The aim of this study was investigate the efficacy of [18F]FCH/PET compared to [18F]FDG/PET in a murine 4T1 mammary carcinoma model treated and nontreated. [18F]FCH/PET showed its applicability for primary tumor and lung metastasis detection and their use for response monitoring of breast cancer therapeutics at earlier stages.

Calcitriol and Its Analogs Establish the Immunosuppressive Microenvironment That Drives Metastasis in 4T1 Mouse Mammary Gland Cancer

In our previous study, calcitriol and its analogs PRI-2191 and PRI-2205 stimulated 4T1 mouse mammary gland cancer metastasis. Therefore, we aimed to analyze the inflammatory response in 4T1-bearing mice treated with these compounds. Gene expression analysis of the splenocytes and regional lymph nodes demonstrated prevalence of the T helper lymphocytes (Th2) response with an increased activity of regulatory T (Treg) lymphocytes in mice treated with these compounds. We also observed an increased number of mature granulocytes and B lymphocytes and a decreased number of TCD4⁺, TCD4⁺CD25⁺, and TCD8⁺, as well as natural killer (NK) CD335⁺, cells in the blood of mice treated with calcitriol and its analogs. Among the splenocytes, we observed a significant decrease in NK CD335⁺ cells and an increase in TCD8⁺ cells. Calcitriol and its analogs decreased the levels of interleukin (IL)-1β and IL-10 and increased the level of interferon gamma (IFN-γ) in the plasma. In the tumor tissue, they caused an increase in the level of IL-10. Gene expression analysis of lung tissue demonstrated an increased level of osteopontin (Spp1) and transforming growth factor β (TGF-β) mRNA. The expression of Spp1 was also elevated in lymph nodes. Calcitriol and its analogs caused prevalence of tumor-conducive changes in the immune system of 4T1 tumor-bearing mice, despite the induction of some tumor-disadvantageous effects.

Off-Target and Tumor-Specific Accumulation of Monocytes, Macrophages and Myeloid-Derived Suppressor Cells after Systemic Injection

Solid tumors frequently coexist with a degree of local chronic inflammation. Recruited myeloid cells can therefore be considered as interesting vehicles for tumor-targeted delivery of therapeutic agents. Using in vivo imaging, the short-term accumulation of systemically injected monocytes, macrophages and myeloid-derived suppressor cells (MDSCs) was compared in mice bearing fat pad mammary carcinomas. Monocytes and macrophages demonstrated almost identical in vivo and ex vivo distribution patterns with maximal tumor-associated accumulation seen 48 hours after injection that remained stable over the 4-day follow-up period. However, a substantial accumulation of both cell types was also seen in the liver, spleen and lungs albeit decreasing over time in all three locations. The MDSCs exhibited a similar distribution pattern as the monocytes and macrophages, but demonstrated a better relative on-target fraction over time. Overall, our findings highlight off-target cell accumulation as a major obstacle in the use of myeloid cells as vehicles for therapeutic tumor-targeted agents and indicate that their short-term on-target accumulation is mainly of nonspecific nature.