Mouse Breast Cancer Research Articles

Effects of low-frequency ultrasound combined with microbubbles on breast cancer xenografts in nude mice.

The aim of this study was to explore the effects of low-frequency ultrasound (US) combined with microbubbles (MBs) on breast cancer xenografts and explain its underlying mechanisms. A total of 20 xenografted nude mice were randomly divided into four groups: a group treated with US plus MBs (the US + MBs group), a group treated with US alone (the US group), a group treated with MBs alone (the MBs group), and a control group. In different groups, mice were treated with different US and injection regimens on an alternate day, three times in total. Histological changes, apoptosis of cells, microvascular changes, and the apoptosis index (AI) and microvascular density (MVD) of the breast cancer xenograft were analyzed after the mice were sacrificed. Results indicated that the tumor volume in the US + MBs group was smaller than that in the other three groups (p < 0.001 for all). The rate of tumor growth inhibition in the US + MBs group was significantly higher than that in the US and MBs groups (p < 0.001 for both). There were no significant differences in histological changes among the four groups. However, the AI was higher in the US + MBs group than that in the other three groups while the MVD was lower (p < 0.001 for all). All in all, low-frequency US combined with MBs can effectively slow down the growth of breast cancer in nude mice. In summary, low-frequency US combined with MBs has a significant effect on breast cancer treatment. Cavitation, thermal effects, and mechanical effects all play a vital role in the inhibition of tumor growth.

Expression of Periostin Alternative Splicing Variants in Normal Tissue and Breast Cancer.

(1) Background: Periostin (Pn) is a secreted protein found in the extracellular matrix, and it plays a variety of roles in the human body. Physiologically, Pn has a variety of functions, including bone formation and wound healing. However, it has been implicated in the pathogenesis of various malignant tumors and chronic inflammatory diseases. Pn has alternative splicing variants (ASVs), and our previous research revealed that aberrant ASVs contribute to the pathogenesis of breast cancer and heart failure. However, the difference in expression pattern between physiologically expressed Pn-ASVs and those expressed during pathogenesis is not clear. (2) Methods and results: We examined normal and breast cancer tissues, focusing on the Pn-ASVs expression pattern to assess the significance of pathologically expressed Pn-ASVs as potential diagnostic and therapeutic targets. We found that most physiologically expressed Pn isoforms lacked exon 17 and 21. Next, we used human breast cancer and normal adjacent tissue (NAT) to investigate the expression pattern of Pn-ASVs under pathological conditions. Pn-ASVs with exon 21 were significantly increased in tumor tissues compared with NAT. In situ hybridization identified the synthesis of Pn-ASVs with exon 21 in peri-tumoral stromal cells. Additionally, the in vivo bio-distribution of 89Zr-labeled Pn antibody against exon 21 (Pn-21Ab) in mice bearing breast cancer demonstrated selective and specific accumulation in tumors, while Pn-21Ab significantly suppressed tumor growth in the mouse breast cancer model. (3) Conclusions: Together, these data indicate that Pn-ASVs might have potential for use as diagnostic and therapeutic targets for breast cancer.

Taohong Siwu decoction enhances the chemotherapeutic efficacy of doxorubicin by promoting tumor vascular normalization

BackgroundInstead of completely suppressing blood vessels inside tumors, vascular normalization therapy is proposed to normalize and prune the abnormal vasculature in tumor microenvironment (TME) to acquire a normal and stable blood flow and perfusion. The theoretical basis for the use of “blood-activating and stasis-resolving” formulas in Traditional Chinese Medicine to treat cancer is highly consistent with the principle of vascular normalization therapy, suggesting the potential application of these traditional formulas in vascular normalization therapy. PurposeTo study the underlying mechanisms of a classical “blood-activating and stasis-resolving” formula, Taohong Siwu decoction (TSD), in enhancing the efficacy of chemotherapy for breast cancer treatment. Study designHUVECs and transgenic zebrafish embryos were used as the major model in vitro. A 4T1 mouse breast cancer model was applied to study tumor vasculature normalization of TSD and the combination effects with DOX. ResultsOur data showed that TSD exhibited anti-angiogenic potential in HUVECs and transgenic zebrafish embryos. After 20 days treatment, TSD significantly normalized the tumor vasculature by remodeling vessel structure, reducing intratumoral hypoxia and vessel leakage, and promoting vessel maturation and blood perfusion in 4T1 breast tumor-bearing mice. Moreover, the anti-tumor efficacy of doxorubicin liposome in 4T1 breast tumors was significantly improved by TSD, including the suppression of tumor cell proliferation, angiogenesis, hypoxia, and the increase of cell apoptosis, which is likely through the vascular normalization induced by TSD. TSD also shifted the macrophage polarization from M2 to M1 phenotype in TME during the combination therapy, as evidenced by the reduced number of CD206+ macrophages and increased number of CD86+ macrophages. Additionally, TSD treatment protected against doxorubicin-induced cardiotoxicity in animals, as evidenced by the reduced cardiomyocytes apoptosis and improved heart function. ConclusionThis study demonstrated for the first time that TSD as a classical Chinese formula can enhance the drug efficacy and reduce the side effects of doxorubicin. These findings can support that TSD could be used as an adjuvant therapy in combination with conventional chemotherapy for the future breast cancer treatment.

Selenium Nanoparticles Synergize with a KRAS Nanovaccine against Breast Cancer.

Selenium (Se) is an element crucial for human health, known for its anticancer properties. Although selenium nanoparticles (SeNPs) have shown lower toxicity and higher biocompatibility than other Se compounds, bare SeNPs are unstable in aqueous solutions. In this study, several materials, including bovine serum albumin (BSA), chitosan, polymethyl vinyl ether-alt-maleic anhydride, and tocopherol polyethylene glycol succinate, are explored to develop stable SeNPs and further evaluate their potential as candidates for cancer treatment. All optimized SeNP are spherical, <100nm, and with a narrow size distribution. BSA-stabilized SeNPs produced under acidic conditions present the highest stability in medium, plasma, and at physiological pH, maintaining their size ≈50-60nm for an extended period. SeNPs demonstrate enhanced toxicity in cancer cell lines while sparing primary human dermal fibroblasts, underscoring their potential as effective anticancer agents. Moreover, the combination of BSA-SeNPs with a nanovaccine results in a strong tumor growth reduction in an EO771 breast cancer mouse model, demonstrating a three-fold decrease in tumor size. This synergistic anticancer effect not only highlights the role of SeNPs as effective anticancer agents but also offers valuable insights for developing innovative combinatorial approaches using SeNPs to improve the outcomes of cancer immunotherapy.

Stimuli-Responsive Phosphate Hydrogel: A Study on Swelling Behavior, Mechanical Properties, and Application in Expansion Microscopy.

Phosphorus-based stimuli-responsive hydrogels have potential in a wide range of applications due to their ionizable phosphorus groups, biocompatibility, and tunable swelling capacity utilizing hydrogel design parameters and external stimuli. In this study, poly(2-methacryloyloxyethyl phosphate) (PMOEP) hydrogels were synthesized via aqueous activators regenerated by electron transfer atomic transfer radical polymerization using ascorbic acid as the reducing agent. Swelling and deswelling behaviors of PMOEP hydrogels were examined in different salt solutions, pH conditions, and temperatures. The degree of swelling in salt solutions followed CaCl2 < MgCl2 < KCl < NaCl with a decrease in swelling rate at higher concentrations until reaching a saturation point. In water, the degree of swelling increased significantly around neutral pH and remained constant at basic pH values. The effects of polymerization conditions, including pH, temperature (30, 40, 50 °C), and MOEP concentration (40, 50, 60% v/v MOEP/H2O), on the hydrogel swelling behavior in various salt solutions were also investigated. PMOEP hydrogels showed a decrease in the degree of swelling as the pH was increased above the native pH of the monomer solution. Scanning electron microscopy and energy-dispersive spectroscopy were utilized to examine the microstructure and chemical composition of the dried hydrogel after salt solution swelling. Cytotoxicity testing using rat bone marrow stem cells confirmed the biocompatibility of the PMOEP hydrogels. A unique feature of this effort was evaluation of these phosphate hydrogels for use in expansion microscopy where a significant twofold enhancement in cellular expansion capacity was showcased utilizing 4T1 mouse breast cancer cells. This comprehensive study provides valuable insights into the stimuli-responsive behavior and expansion characteristics of phosphate hydrogels, highlighting their potential in diverse biomedical applications.

Extracellular vesicles derived from mesenchymal stem cells suppress breast cancer progression by inhibiting angiogenesis.

Previous studies have highlighted the antitumor effects of mesenchymal stem cell‑derived extracellular vesicles (MSC‑EVs), positioning them as a promising therapeutic avenue for cancer treatment. However, some researchers have proposed a bidirectional influence of MSC‑EVs on tumors, determined by the specific tissue origin of the MSCs and the types of tumors involved. The present study aimed to elucidate the effects of human placenta MSC‑derived extracellular vesicles (hPMSC‑EVs) on the malignant behavior of a mouse breast cancer model of 4T1 cells in vitro and in vivo. The findings revealed that hPMSC‑EVs significantly inhibited the proliferation, migration and colony formation of cultured 4T1 mouse breast cancer cells without inducing apoptosis. Exposure to conditioned medium from 4T1 cells pretreated with hPMSC‑EVs resulted in decreased angiogenic activity, accompanied by the downregulation of angiogenesis‑promoting genes in human umbilical vein endothelial cells. In murine xenograft models derived from the 4T1 cell line, local administration of hPMSC‑EVs substantially hindered tumor growth. Further results revealed that hPMSC‑EVs inhibited angiogenesis in vivo, as reflected by the use of a vascular growth factor receptor 2‑Fluc transgenic mouse model. In summary, the results confirmed that hPMSC‑EVs negatively modulated breast cancer growth by suppressing tumor cell proliferation and migration via an indirect antiangiogenic mechanism. These results underscored the therapeutic potential of EVs, suggesting a promising avenue for alternative anticancer treatments in the future.

Light-Responsive conjugated polymer nanoparticles with Spatial-Controlled camptothecin release via π − π stacking for improved Combinatorial therapy of breast cancer

The treatment of breast cancer (BC) remains a significant challenge, exemplified by the limitations of chemotherapy due to its high side effects. Light-responsive drug delivery systems (DDS) offer a promising approach to spatially and temporally release drugs, minimizing chemotherapy side effects and enhancing efficacy. However, achieving precise delivery and site-specific drug release poses complex challenges. Here, We present a novel nano-system combining light-responsive photothermal therapy (PTT) with photothermal-responsive chemotherapy via π − π Stacking. Conjugated polymer nanoparticles (cRGD-PTer N25/CPT NPs) is designed for spatiotemporal targeted PTT/chemotherapy. Research shows that the strong near-infrared absorption of PTer N25 endows cRGD-PTer N25/CPT NPs with excellent photothermal capabilities(57.4 %) and near-infrared laser-triggered drug release performance. The cRGD-PTer N25/CPT NPs enhanced BC-specific cellular accumulation, prolonged blood circulation, exhibited good biocompatibility, and improved PTT and chemotherapy efficacy in BC cell lines and mouse models while reducing systemic toxicity. The photothermal effect triggered the on-demand release of camptothecin (CPT), producing therapeutic effects and downregulating heat shock protein 70 (HSP 70), reducing cancer cell thermoresistance, and enhancing combined treatment efficacy. Under spatial and temporal control, the tumor growth inhibition rate of the cRGD-PTer N25/CPT NPs group reached 93.6 %, nearly eradicating tumor presence, whereas the control group exhibited only partial inhibition. Minimal cardiotoxicity and metastatic side effects are not observed. This work presents a viable strategy for designing novel controlled-release drug systems to improve breast cancer treatment efficiency.

Inflammation and Tumor Progression: The Differential Impact of SAA in Breast Cancer Models.

Background: Previous research has shown that the Serum Amyloid A (SAA) protein family is intricately involved in inflammatory signaling and various disease pathologies. We have previously demonstrated that SAA is associated with increased colitis disease severity and the promotion of tumorigenesis. However, the specific role of SAA proteins in breast cancer pathology remains unclear. Therefore, we investigated the role of systemic SAA1 and SAA2 (SAA1/2) in a triple-negative breast cancer mouse model. Methods: Syngeneic breast tumors were established in wild-type mice, and mice lacking the SAA1/2 (SAADKO). Subsequently, tumor volume was monitored, species survival determined, the inflammatory profiles of mice assessed with a multiplex assay, and tumor molecular biology and histology characterized with Western blotting and H&E histological staining. Results: WT tumor-bearing mice had increased levels of plasma SAA compared to wild-type control mice, while SAADKO control and tumor-bearing mice presented with lower levels of SAA in their plasma. SAADKO tumor-bearing mice also displayed significantly lower concentrations of systemic inflammatory markers. Tumors from SAADKO mice overall had lower levels of SAA compared to tumors from wild-type mice, decreased apoptosis and inflammasome signaling, and little to no tumor necrosis. Conclusions: We demonstrated that systemic SAA1/2 stimulates the activation of the NLRP3 inflammasome in breast tumors, leading to the production of pro-inflammatory cytokines. This, in turn, promoted apoptosis and tumor necrosis but did not significantly impact tumor growth or histological grading.

Tumor Metabolism Aiming Cu2-xS Nanoagents Mediate Photothermal-Derived Cuproptosis and Immune Activation.

Cuproptosis is an emerging form of cell death that relies on the targeted delivery of copper ions to lipoylated tricarboxylic acid cycle proteins. However, a major challenge associated with cuproptosis is its potential to kill both normal and tumor cells without discrimination. Therefore, it is crucial to develop strategies for precise intracellular delivery and redox control of copper to create effective cuproptosis-based tumor therapies. We have introduced a class of nanoagents called metabolism aiming Cu2-xS (MACuS) through a glucose-mediated biomineralization approach. MACuS nanoagents can be specifically targeted to tumors via the glucose transport receptor 1, and we found that NIR-II irradiation can not only result in direct hyperthermia ablation of tumor cells but also facilitate efficient cuproptosis and enhance reactive oxygen species-induced cytotoxicity in tumor cells. As a result, the triple effect of MACuS treatment induced immunogenic cell death, which triggered systemic antitumor immune responses and demonstrated potent efficacy in inhibiting growth, metastasis, and recurrence in mouse and rabbit breast cancer models. The precise intracellular delivery and redox control of copper provided by MACuS hold great potential for the development of highly efficient cuproptosis-based tumor therapies with minimal off-target effects.

Fertility protection during chemotherapy treatment by boosting the NAD(P)+ metabolome.

Chemotherapy induced ovarian failure and infertility is an important concern in female cancer patients of reproductive age or younger, and non-invasive, pharmacological approaches to maintain ovarian function are urgently needed. Given the role of reduced nicotinamide adenine dinucleotide phosphate (NADPH) as an essential cofactor for drug detoxification, we sought to test whether boosting the NAD(P)+ metabolome could protect ovarian function. We show that pharmacological or transgenic strategies to replenish the NAD+ metabolome ameliorates chemotherapy induced female infertility in mice, as measured by oocyte yield, follicle health, and functional breeding trials. Importantly, treatment of a triple-negative breast cancer mouse model with the NAD+ precursor nicotinamide mononucleotide (NMN) reduced tumour growth and did not impair the efficacy of chemotherapy drugs in vivo or in diverse cancer cell lines. Overall, these findings raise the possibility that NAD+ precursors could be a non-invasive strategy for maintaining ovarian function in cancer patients, with potential benefits in cancer therapy.

A long-wavelength fluorescent probe based on carbazole with AIE characteristics for the detection of ONOO− and its application

Peroxynitrite (ONOO−) is an important reactive oxygen species, and excess ONOO− in the body can lead to a range of diseases. Addressing the need for sensitive detection ONOO−, in this work, a highly sensitivity and selectivity long-wavelength fluorescent probe (named CIS) was designed for tracking ONOO− in biological cells. Probe CIS featured carbazole as the fluorophore and the CC double bond with two electron withdrawing –CN groups as the recognition site. The probe CIS exhibited the typical aggregation-induced emission (AIE) and intramolecular charge transfer (ICT) characteristics with the bright red fluorescent emission in high water fraction (fw ≥ 50 %) and negligible emission in low water fraction. The fluorescence emission wavelength of probe CIS is 631 nm, with a large Stokes shift (151 nm), which can sensitively detect ONOO− in DMSO: H2O (7:3, v/v) environment. Notably, the probe CIS exhibited a wide pH detection range (pH = 3–10), a low detection limit of 36.66 nM, high selectivity and minimal interference. Furthermore, probe CIS demonstrated excellent biocompatibility and low cytotoxicity, and can be used for the detection of exogenous ONOO− in 4T1 cells (Mouse breast cancer cells). These research results indicate that probe CIS has potential application prospects in the biological aspects.

A nanobody against the V-ATPase c subunit inhibits metastasis of 4T1-12B breast tumor cells to lung in mice.

The vacuolar H+-ATPase (V-ATPase) is an ATP-dependent proton pump that functions to control the pH of intracellular compartments as well as to transport protons across the plasma membrane of various cell types, including cancer cells. We have previously shown that selective inhibition of plasma membrane V-ATPases in breast tumor cells inhibits the invasion of these cells in vitro. We have now developed a nanobody directed against an extracellular epitope of the mouse V-ATPase c subunit. We show that treatment of 4T1-12B mouse breast cancer cells with this nanobody inhibits V-ATPase-dependent acidification of the media and invasion of these cells in vitro. We further find that injection of this nanobody into mice implanted with 4T1-12B cells orthotopically in the mammary fat pad inhibits metastasis of tumor cells to lung. These results suggest that plasma membrane V-ATPases represent a novel therapeutic target to limit breast cancer metastasis.

Novel humanized monoclonal antibodies against ROR1 for cancer therapy

BackgroundOverexpression of receptor tyrosine kinase-like orphan receptor 1 (ROR1) contributes to cancer cell proliferation, survival and migration, playing crucial roles in tumor development. ROR1 has been proposed as a potential therapeutic target for cancer treatment. This study aimed to develop novel humanized ROR1 monoclonal antibodies and investigate their anti-tumor effects.MethodsROR1 expression in tumor tissues and cell lines was analyzed by immunohistochemistry and flow cytometry. Antibodies from mouse hybridomas were humanized by the complementarity-determining region (CDR) grafting technique. Surface plasmon resonance spectroscopy, ELISA assay and flow cytometry were employed to characterize humanized antibodies. In vitro cellular assay and in vivo mouse experiment were conducted to comprehensively evaluate anti-tumor activity of these antibodies.ResultsROR1 exhibited dramatically higher expression in lung adenocarcinoma, liver cancer and breast cancer, and targeting ROR1 by short-hairpin RNAs significantly inhibited proliferation and migration of cancer cells. Two humanized ROR1 monoclonal antibodies were successfully developed, named h1B8 and h6D4, with high specificity and affinity to ROR1 protein. Moreover, these two antibodies effectively suppressed tumor growth in the lung cancer xenograft mouse model, c-Myc/Alb-cre liver cancer transgenic mouse model and MMTV-PyMT breast cancer mouse model.ConclusionsTwo humanized monoclonal antibodies targeting ROR1, h1B8 and h6D4, were successfully developed and exhibited remarkable anti-tumor activity in vivo.

Photocatalytic Carbon Dots-Triggered Pyroptosis for Whole Cancer Cell Vaccines.

Manufacturing whole cancer cell vaccines (WCCV) with both biosafety and efficacy is crucial for tumor immunotherapy. Pyroptotic cancer cells, due to their highly immunogenic properties, present a promising avenue for the development of WCCV. However, the successful development of WCCV based on pyroptotic cancer cells is yet to be accomplished. Here, a facile strategy that utilized photocatalytic carbon dots (CDs) to induce pyroptosis of cancer cells for fabricating WCCV is reported. Photocatalytic CDs are capable of generating substantial amounts of hydroxyl radicals and can effectively decrease cytoplasmic pH values under white light irradiation. This process efficiently triggers cancer cell pyroptosis through the reactive oxygen species (ROS)-mitochondria-caspase 3-gasdermin E pathway and the proton motive force-driven mitochondrial ATP synthesis pathway. Moreover, in vitro, these photocatalytic CDs-induced pyroptotic cancer cells (PCIP) can hyperactivate macrophage (M0-M1) with upregulation of major histocompatibility complex class II expression. In vivo, PCIP induced specific immune-preventive effects in melanoma and breast cancer mouse models through anticancer immune memory, demonstrating effective WCCV. This work provides novel insights for inducing cancer cell pyroptosis and bridges the gap in the fabrication of WCCV based on pyroptotic cancer cells.

The Host miR-17-92 Cluster Negatively Regulates Mouse Mammary Tumor Virus (MMTV) Replication Primarily Via Cluster Member miR-92a

The mouse mammary tumor virus (MMTV) is a well-known causative agent of breast cancer in mice. Previously, we have shown that MMTV dysregulates expression of the host miR-17-92 cluster in MMTV-infected mammary glands and MMTV-induced tumors. This cluster, better known as oncomiR-1, is frequently dysregulated in cancers, particularly breast cancer. In this study, our aim was to uncover a functional interaction between MMTV and the cluster. Our results reveal that MMTV expression led to dysregulation of the cluster in both mammary epithelial HC11 and HEK293T cells with the expression of miR-92a cluster member being affected the most. Conversely, overexpression of the whole or partial cluster significantly repressed MMTV expression. Notably, overexpression of cluster member miR-92a alone repressed MMTV expression to the same extent as overexpression of the complete/partial cluster. Inhibition of miR-92a led to nearly a complete restoration of MMTV expression, while deletion/substitution of the miR-92a seed sequence rescued MMTV expression. Dual luciferase assays identified MMTV genomic RNA as the potential target of miR-92a. These results show that the miR-17-92 cluster acts as part of the cell’s well-known miRNA-based anti-viral response to thwart incoming MMTV infection. Thus, this study provides the first evidence highlighting the biological significance of host miRNAs in regulating MMTV replication and potentially influencing tumorigenesis.

Natural Killer Cell Regulation of Breast Cancer Stem Cells Mediates Metastatic Dormancy.

Patients with breast cancer with estrogen receptor-positive tumors face a constant risk of disease recurrence for the remainder of their lives. Dormant tumor cells residing in tissues such as the bone marrow may generate clinically significant metastases many years after initial diagnosis. Previous studies suggest that dormant cancer cells display "stem-like" properties (cancer stem cell, CSC), which may be regulated by the immune system. To elucidate the role of the immune system in controlling dormancy and its escape, we studied dormancy in immunocompetent, syngeneic mouse breast cancer models. Three mouse breast cancer cell lines, PyMT, Met1, and D2.0R, contained CSCs that displayed short- and long-term metastatic dormancy in vivo, which was dependent on the host immune system. Each model was regulated by different components of the immune system. Natural killer (NK) cells were key for the metastatic dormancy phenotype in D2.0R cells. Quiescent D2.0R CSCs were resistant to NK cell cytotoxicity, whereas proliferative CSCs were sensitive. Resistance to NK cell cytotoxicity was mediated, in part, by the expression of BACH1 and SOX2 transcription factors. Expression of STING and STING targets was decreased in quiescent CSCs, and the STING agonist MSA-2 enhanced NK cell killing. Collectively, these findings demonstrate the role of immune regulation of breast tumor dormancy and highlight the importance of utilizing immunocompetent models to study this phenomenon. Significance: The immune system controls disseminated breast cancer cells during disease latency, highlighting the need to utilize immunocompetent models to identify strategies for targeting dormant cancer cells and reducing metastatic recurrence. See related commentary by Cackowski and Korkaya, p. 3319.

Folate Receptor β (FRβ) Expression on Myeloid Cells and the Impact of Reticuloendothelial System on Folate-Functionalized Nanoparticles' Biodistribution in Cancer.

Folate uptake is largely mediated by folate receptor (FR)β, encoded by FOLR2 gene, in myeloid immune cells such as granulocytes, monocytes, and especially in macrophages that constitute the reticuloendothelial system (RES) and infiltrate the tumor microenvironment. Since the myeloid immune compartment dynamically changes during tumorigenesis, it is critical to assess the infiltration status of the tumors by FRβ-expressing myeloid cells to better define the targeting efficacy of folate-functionalized drug delivery systems. On the other hand, clearance by RES is a major limitation for the targeting efficacy of nanoparticles decorated with folate. Therefore, the aims of this study are (i) to determine the amount and subtypes of FRβ+ myeloid cells infiltrating the tumors at different stages, (ii) to compare the amount and subtype of FRβ+ myeloid cells in distinct organs of tumor-bearing and healthy animals, (iii) to test if the cancer-targeting efficacy and biodistribution of a prototypic folate-functionalized nanoparticle associates with the density of FRβ+ myeloid cells. Here, we report that myeloid cell infiltration was enhanced and FRβ was upregulated at distinct stages of tumorigenesis in a mouse breast cancer model. The CD206+ subset of macrophages highly expressed FRβ, prominently both in tumor-bearing and healthy mice. In tumor-bearing mice, the amount of all myeloid cells, but particularly granulocytes, was remarkably increased in the tumor, liver, lungs, spleen, kidneys, lymph nodes, peritoneal cavity, bone marrow, heart, and brain. Compared with macrophages, the level of FRβ was moderate in granulocytes and monocytes. The density of FRβ+ immune cells in the tumor microenvironment was not directly associated with the tumor-targeting efficacy of the folate-functionalized cyclodextrin nanoparticles. The lung was determined as a preferential site of accumulation for folate-functionalized nanoparticles, wherein FRβ+CD206+ macrophages significantly engulfed cyclodextrin nanoparticles. In conclusion, our results demonstrate that the tumor formation augments the FR levels and alters the infiltration and distribution of myeloid immune cells in all organs which should be considered as a major factor influencing the targeting efficacy of nanoparticles for drug delivery.

PET imaging of colon cancer CD73 expression using cysteine site-specific 89Zr-labeled anti-CD73 antibody

CD73 is a cell-surface ectoenzyme that hydrolyzes the conversion of extracellular adenosine monophosphate to adenosine, which in turn can promote resistance to immune checkpoint blockade therapy. Immune response may therefore be improved by targeting tumor CD73, and this possibility underlines the need to non-invasively assess tumor CD73 level. In this study, we developed a cysteine site-specific 89Zr-labeled anti-CD73 (89Zr-CD73) IgG immuno-PET technique that can image tumor CD73 expression in living bodies. Anti-CD73 IgG was reduced with tris(2-carboxyethyl)phosphine, underwent sulfohydryl moiety–specific conjugation with deferoxamine–maleimide, and was radiolabeled with 89Zr. CT26 mouse colon cancer cells, CT26/CD73 cells engineered to constitutively overexpress CD73, and 4T1.2 mouse breast cancer cells underwent cell binding assays and western blotting. Balb/c nude mice bearing tumors underwent 89Zr-CD73 IgG PET imaging and biodistribution studies. 89Zr-CD73 IgG showed 20-fold higher binding to overexpressing CT26/CD73 cells compared to low-expressing CT26 cells, and moderate expressing 4T1.2 cells showed uptake that was 38.9 ± 1.51% of CT26/CD73 cells. Uptake was dramatically suppressed by excess unlabeled antibody. CD73 content proportionately increased in CT26 and CT26/CD73 cell mixtures was associated with linear increases in 89Zr-CD73 IgG uptake. 89Zr-CD73 IgG PET/CT displayed clear accumulation in CT26/CD73 tumors with greater uptake compared to CT26 tumors (3.13 ± 1.70%ID/g vs. 1.27 ± 0.31%ID/g at 8 days; P = 0.04). Specificity was further supported by low CT26/CD73 tumor-to-blood ratio of 89Zr-isotype-IgG compared to 89Zr-CD73 IgG (0.48 ± 0.08 vs. 2.68 ± 0.52 at 4 days and 0.53 ± 0.07 vs. 4.81 ± 1.02 at 8 days; both P < 0.001). Immunoblotting and immunohistochemistry confirmed strong CD73 expression in CT26/CD73 tumors and low expression in CT26 tumors. 4T1.2 tumor mice also showed clear 89Zr-CD73 IgG accumulation at 8 days (3.75 ± 0.70%ID/g) with high tumor-to-blood ratio compared to 89Zr-isotype-IgG (4.91 ± 1.74 vs. 1.20 ± 0.28; P < 0.005). 89Zr-CD73 IgG specifically targeted CD73 on high expressing cancer cells in vitro and tumors in vivo. Thus, 89Zr-CD73 IgG immuno-PET may be useful for the non-invasive monitoring of CD73 expression in tumors of living subjects.

The F-actin bundler SWAP-70 promotes tumor metastasis.

Dynamic rearrangements of the F-actin cytoskeleton are a hallmark of tumor metastasis. Thus, proteins that govern F-actin rearrangements are of major interest for understanding metastasis and potential therapies. We hypothesized that the unique F-actin binding and bundling protein SWAP-70 contributes importantly to metastasis. Orthotopic, ectopic, and short-term tail vein injection mouse breast and lung cancer models revealed a strong positive dependence of lung and bone metastasis on SWAP-70. Breast cancer cell growth, migration, adhesion, and invasion assays revealed SWAP-70's key role in these metastasis-related cell features and the requirement for SWAP-70 to bind F-actin. Biophysical experiments showed that tumor cell stiffness and deformability are negatively modulated by SWAP-70. Together, we present a hitherto undescribed, unique F-actin modulator as an important contributor to tumor metastasis.

IRGD-Guided Silica/Gold Nanoparticles for Efficient Tumor-Targeting and Enhancing Antitumor Efficacy Against Breast Cancer.

Breast cancer presents significant challenges due to the limited effectiveness of available treatments and the high likelihood of recurrence. iRGD possesses both RGD sequence and C-terminal sequence and has dual functions of targeting and membrane penetration. iRGD-modified nanocarriers can enhance drug targeting of tumor vascular endothelial cells and penetration of new microvessels, increasing drug concentration in tumor tissues. The amidation reaction was carried out between SiO2/AuNCs and iRGD/PTX, yielding a conjugated drug delivery system (SiO2/AuNCs-iRGD/PTX, SAIP@NPs). The assessment encompassed the characterization of the morphology, particle size distribution, physicochemical properties, in vitro release profile, cytotoxicity, and cellular uptake of SAIP@NPs. The tumor targeting and anti-tumor efficacy of SAIP@NPs were assessed using a small animal in vivo imaging system and a tumor-bearing nude mice model, respectively. The tumor targeting and anti-tumor efficacy of SAIP@NPs were assessed utilizing a small animal in vivo imaging system and an in situ nude mice breast cancer xenograft model, respectively. The prepared SAIP@NPs exhibited decent stability and a certain slow-release effect in phosphate buffer (PBS, pH 7.4). In vitro studies had shown that, due to the dual functions of transmembrane and targeting of iRGD peptide, SAIP@NPs exhibited strong binding to integrin αvβ3, which was highly expressed on the membrane of MDA-MB-231 cells, improving the uptake capacity of tumor cells, inhibiting the rapid growth of tumor cells, and promoting tumor cell apoptosis. The results of animal experiments further proved that SAIP@NPs had longer residence time in tumor sites, stronger anti-tumor effect, and no obvious toxicity to major organs of experimental animals. The engineered SAIP@NPs exhibited superior functionalities including efficient membrane permeability, precise tumor targeting, and imaging, thereby significantly augmenting the therapeutic efficacy against breast cancer with a favorable safety profile.