Metastatic Breast Cancer Cell Line Research Articles

TMIC-48. THREE DIMENSIONAL CANCER CELL-MONOCYTE CO-CULTURE SPHEROIDS RECAPITULATE IMMUNOSUPPRESSIVE AND PRO-TUMORIGENIC MICROENVIRONMENTS IN BRAIN METASTATIC BREAST CANCER

Abstract Brain metastasis occurs in 15 % of breast cancer patients and is one of the major causes of breast cancer related morbidity. Brain metastatic breast cancer (BMBC) microenvironment is a heterogeneous niche of cellular and acellular components of which the innate immune cells, microglia, and macrophages, comprise the major fraction. However, the role of these innate immune cells in the tumor microenvironment (TME) in mediating cancer progression and response to therapy is not well understood. To address this need, herein, we developed three dimensional (3D) co-culture spheroids using brain metastatic triple negative breast cancer (TNBC) cell line MDA-MB-231Br or patient derived brain metastatic TNBC cell line F2-7 with THP1 monocytes. Under co-culture conditions MDA-MB-231Br co-culture spheroids assumed highly protrusive morphology with enhanced mesenchymal and proliferative characteristics. Additionally, phenotypic determination of cocultured macrophages revealed elevated levels of markers associated with alternatively activated macrophages i.e. CD163, CD206, and c-Myc. Furthermore, we found that under coculture conditions immunosuppressive and evasive markers PD1, PDL1, CD47 and CD24 were significantly upregulated. Similarly, F2-7 and monocyte cocultures also led to an immunosuppressive environment with elevated levels of M2 type markers and associated anti-inflammatory cytokines. We further found that the presence of M2 type macrophages in the microenvironment of BMBC spheroids led to acquired resistance against Paclitaxel, a clinically relevant chemotherapeutic drug against BMBC. In sum, in our coculture conditions, brain metastatic TNBC cells polarized monocytes into immunosuppressive and pro-tumorigenic tumor associated macrophages leading to a pro-tumoral microenvironment. Thus, 3D co-culture spheroids of BMBC cells and monocytes can serve as robust platform for studying cancer cell and innate immune cell interactions occurring in the BMBC environment.

Abstract A048: The Loss of Cholesterol Efflux Pump ABCA1 Skews Macrophages Towards a Pro-tumor Phenotype and Facilitates Breast Cancer Progression

Abstract Breast cancer is the most common and second-leading cause of cancer-related fatalities in women in the United States. The primary cause of mortality is often the recurrence of metastatic breast cancer. While immunotherapy shows some effectiveness, it has only been approved for patients who stain positive for PD-L1. Previous research in our lab has shown that macrophage function can be regulated through disruption in cholesterol metabolism. Additionally, elevated plasma cholesterol levels have been associated with breast cancer recurrence. These findings underscore the impact of cholesterol homeostasis in tumor-associated macrophages on breast cancer progression. An in-depth computational screen helped us pinpoint ABCA1—a cholesterol efflux protein whose elevated mRNA expression linked to increased survival. In addition to efflux, ABCA1 can also translocate cholesterol from the inner leaflet of the plasma membrane to the outer layer. Highlighting the clinical importance of ABCA1 are our findings that show that increased ABCA1 levels within breast tumors correlate to an increase in cytotoxic T Cells, and T cell effector enzymes (Prf-1 and Gzmb), and improved survival rates. Importantly, our in vitro studies suggest that ABCA1 influences several functions of macrophages relevant to tumor biology. Specifically, ABCA1 shifts macrophages towards an anti-cancer phenotype by (1) increasing their ability to infiltrate tumor spheroids, (2) decreasing angiogenesis, (3) decreasing efferocytosis—an immune-suppressive phagocytic process devoid of antigen presentation, and (4) enhancing the expansion, migration, and activity of cytotoxic T cells. The culmination of these attributes were demonstrated by our observations that syngeneic grafts of E0771 mammary tumors grew at an accelerated rate in mice with a myeloid-specific knockout of ABCA1 (ABCA1fl/fl;LysMcre+) compared to control mice. ABCA1 transports cholesterol from macrophages to a lipid-poor ApoA1 protein and facilitates the formation of nascent HDL via the reverse cholesterol transport pathway. We leveraged this mechanism to therapeutically target ABCA1 using ApoA1 mimetics 5A and 4F. Our data so far indicates that ApoA1 mimetics phenocopy ABCA1 overexpression skewing macrophages towards an anti-tumor phenotype. Importantly, treatment with 5A in mice grafted with 4T1 metastatic breast cancer cell line resulted in marked reduction in tumor burden. Additionally, we observed an increased infiltration of cytotoxic T cells and a decrease in CD31 expression, suggesting reduced blood vessel formation. Collectively, our data strongly supports the role of ABCA1 in the development of breast cancer. The expected results from this research will lay the groundwork for future therapeutic strategies for the use of ABCA1 and ApoA1 mimetics in the treatment of breast cancer. Citation Format: Shruti Bendre, Natalia Krawczynska, Shaunak Bhogale, Erin Weisser, Simon Han, Basel Hajyousif, Avni Singh, Rajendra KC, Yu Wang, Claire P Schane, Adam T Nelczyk, Dhanya Pradeep, Lara Kockaya, Hashni Epa Vidana Gamage, Kevin VanBortle, Emad Tajkorshid, Saurabh Sinha, Wendy A Woodward, Wonhwa Cho, Erik R Nelson. The Loss of Cholesterol Efflux Pump ABCA1 Skews Macrophages Towards a Pro-tumor Phenotype and Facilitates Breast Cancer Progression [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2024 Oct 18-21; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2024;12(10 Suppl):Abstract nr A048.

Substrate stiffness modulates extracellular vesicles’ release in a triple-negative breast cancer model

Aim: The microenvironment effect on the tumoral-derived Extracellular Vesicle release, which is of significant interest for biomedical applications, still represents a rather unexplored field. The aim of the present work is to investigate the interrelation between extracellular matrix (ECM) stiffness and the release of small EVs from cancer cells. Here, we focus on the interrelation between the ECM and small extracellular vesicles (sEVs), specifically investigating the unexplored aspect of the influence of ECM stiffness on the release of sEVs. Methods: We used a well-studied metastatic Triple-Negative Breast Cancer (TNBC) cell line, MDA-MB-231, as a model to study the release of sEVs by cells cultured on substrates of different stiffness. We have grown MDA-MB-231 cells on two collagen-coated polydimethylsiloxane (PDMS) substrates at different stiffness (0.2 and 3.6 MPa), comparing them with a hard glass substrate as control, and then we isolated the respective sEVs by differential ultracentrifugation. After checking the cell growth conditions [vitality, morphology by immunofluorescence microscopy, stiffness by atomic force microscopy (AFM)], we took advantage of a multi-parametric approach based on complementary techniques (AFM, Nanoparticle Tracking Analysis, and asymmetric flow field flow fractionation with a multi-angle light scattering detector) to characterize the TNBC-derived sEV obtained in the different substrate conditions. Results: We observe that soft substrates induce TNBC cell softening and rounding. This effect promotes the release of a high number of larger sEVs. Conclusion: Here, we show the role of ECM physical properties in the regulation of sEV release in a TNBC model. While the molecular mechanisms regulating this effect need further investigation, our report represents a step toward an improved understanding of ECM-cell-sEVs crosstalk.

ANKRD1 Promotes Breast Cancer Metastasis by Activating NF-κB-MAGE-A6 Pathway.

Early detection and surgical excision of tumors have helped improve the survival rate of patients with breast cancer. However, patients with metastatic cancer typically have a poor prognosis. In this study, we propose that ANKRD1 promotes metastasis of breast cancer. ANKRD1 was found to be highly expressed in the MDA-MB-231 and MDA-LM-2 highly metastatic breast cancer cell lines compared to the non-metastatic breast cancer cell lines (MCF-7, ZR-75-30, T47D) and normal breast cancer cells (MCF-10A). Furthermore, high-grade tumors showed increased levels of ANKRD1 compared to low-grade tumors. Both in vitro and in vivo functional studies demonstrated the essential role of ANKRD1 in cancer cell migration and invasion. The previous studies have suggested a significant role of NF-κB and MAGE-A6 in breast cancer metastasis, but the upstream regulators of this axis are not well characterized. Our study suggests that ANKRD1 promotes metastasis of breast cancer by activating NF-κB as well as MAGE-A6 signaling. Our findings show that ANKRD1 is a potential therapeutic target and a diagnostic marker for breast cancer metastasis.

Comparative Study of the Effects of Docosahexaenoic Acid, Linoleic Acid, and Taxol in Decreasing the Expression of miR-10b, and miR-20a OncomiRs, and their Target Major Histocompatibility Complex Class I Chain-Related Proteins A (MICA) in Triple-Negative Metastatic Breast Cancer Cell Line

Background: Molecular signatures of the effects of widely used omega-3 and omega-6 fatty acids as dietary supplements and even in cancer therapy have been studied. Of them, microRNAs, have been shown to undergo altered expression after treatment with docosahexaenoic acid (DHA) and linoleic acid (LA) in different cancer types. In this study, the expression level of two well-known onco-microRNAs (miR), miR-10b and miR-20a, and also major histocompatibility complex class I chain-related protein A (MICA) as the target for these oncomiRs were investigated after treatment with DHA, LA, and common therapeutic agent Taxol. Methods: MDA-MB-231 cells were cultured in a complete RPMI 1640 medium and an MTT assay was performed to determine IC50 of DHA, LA, and Taxol. Cells were treated by DHA (100µM), LA (50µM), and Taxol (0.3µM) alone or in different combinations. After RNA extraction and cDNA synthesis, the expression levels of miR-10b, miR-20a, and MICA were determined by quantitative real-time PCR. U6 and β-Actin were used as endogenous controls, respectively. Results: Our findings showed that DHA, LA, and Taxol, and their combinations led to the significantly decreased expression of miR-10b and miR-20a (all P<0.0001). The expression level of miR-10b and miR-20a significantly decreased when treated with the LA+TAX combination. MICA as the target of miR-10b and miR-20a was also down-regulated significantly (P<0.0001) especially when treated with DHA+LA+TAX. Conclusion: Useful effects of DHA, LA, and their combination in breast cancer (BC) could be interpreted in part by decreasing the expression level of oncomiRs. In the case of MICA have had some contrary. High expression of MICA/B caused an approving outcome concerning the relapse-free period in early BC patients, however; some studies have shown that higher MICA expression was found as a sign of poor prognosis in BC. The decreased expression of MICA in the present study suggests the potential role of DHA and LA should be used in dietary supplements of BC patients.

Endosomal protein DENND10/FAM45A integrates extracellular vesicle release with cancer cell migration

BackgroundMounting evidence shows that tumor-derived extracellular vesicles (EVs) are critical constituents in the tumor microenvironment. The composition and function of EVs often change during cancer progression. However, it remains less clear how cancer cells modulate their own EV biogenesis to promote tumor development. The release of EVs is closely linked to the endolysosome system residing within the cell. The current study aims to decipher the role of endosomal protein DENND10 in cancer development.ResultsBioinformatics data mining showed that DENND10 expression is significantly associated with poor prognosis in multiple cancer types and up-regulated in metastatic breast cancer cell lines. DENND10 knockout (DENND10-KO) in breast cancer cells led to defective EV biogenesis due to impaired endolysosomal trafficking. Intriguingly, DENND10-KO cells exhibited reductions in cell spreading, migration, invasion, and metastatic potential in vivo. These deficiencies in cell motility were associated with compromised cytoskeleton organization. Importantly, wild-type conditioned medium or EVs restored the migratory ability and cytoskeletal organization of DENND10-KO cells. Global proteomic profiling revealed that DENND10 depletion led to a distinct EV compositional landscape with remodeled profiles of extracellular matrix (ECM) and adhesion molecules. Consistently, exogenous application of ECM molecules rescued the spreading and migration of DENND10-KO cells.ConclusionsIn summary, our study unveiled DENND10 as an intrinsic regulator of cell migration that modifies the tumor microenvironment through autocrine EV release, which could be exploited for developing targeted therapies for tumor metastasis.

Inhibition of glycolysis and Src/Akt signaling reduces Caveolin-1-enhanced metastasis

Metastasis is the leading cause of cancer-related deaths, making the development of novel, more effective therapies imperative to alleviate patient suffering. Metabolic switching is a hallmark of cancer cells that facilitates metastasis. Cancer cells obtain most of their energy and intermediate metabolites, which are required to proliferate and metastasize, through aerobic glycolysis. Previous work from our laboratory has shown that Caveolin-1 (CAV1) expression in cancer cells promotes glycolysis and metastasis. Here, we sought to determine if limiting glycolysis reduced CAV1-enhanced metastasis and to identify the mechanism(s) involved. We evaluated the effects of the glycolysis inhibitor 2-deoxy-D-glucose (2-DG) in metastatic melanoma and breast cancer cell lines expressing or not CAV1. Non-cytotoxic concentrations of 2-DG (1 mM) inhibited the migration of B16-F10 melanoma and MDA-MB-231 breast cancer cells. CAV1-mediated activation of Src/Akt signaling was required for CAV1-enhanced migration and was blocked in the presence of 2-DG. Moreover, inhibition of Akt reduced CAV1-enhanced lung metastasis of B16-F10 cells. Collectively, these findings highlight the importance of CAV1-induced metabolic reprogramming for metastasis and point towards possible therapeutic approaches to prevent metastatic disease by inhibiting glycolysis and Src/Akt signaling.

A NIR-Fluorochrome for Live Cell Dual Emission and Lifetime Tracking from the First Plasma Membrane Interaction to Subcellular and Extracellular Locales.

Molecular probes with the ability to differentiate between subcellular variations in acidity levels remain important for the investigation of dynamic cellular processes and functions. In this context, a series of cyclic peptide and PEG bio-conjugated dual near-infrared emissive BF2-azadipyrromethene fluorophores with maxima emissions at 720 nm (at pH > 6) and 790 nm (at pH < 5) have been developed and their aqueous solution photophysical properties determined. Their inter-converting emissions and fluorescence lifetime characteristics were exploited to track their spatial and temporal progression from first contact with the plasma membrane to subcellular locales to their release within extracellular vesicles. A pH-dependent reversible phenolate/phenol interconversion on the fluorophore controlled the dynamic changes in dual emission responses and corresponding lifetime changes. Live-cell confocal microscopy experiments in the metastatic breast cancer cell line MDA-MB-231 confirmed the usability of the dual emissive properties for imaging over prolonged periods. All three derivatives performed as probes capable of real-time continuous imaging of fundamental cellular processes such as plasma membrane interaction, tracking endocytosis, lysosomal/large acidic vesicle accumulation, and efflux within extracellular vesicles without perturbing cellular function. Furthermore, fluorescence lifetime imaging microscopy provided valuable insights regarding fluorophore progression through intracellular microenvironments over time. Overall, the unique photophysical properties of these fluorophores show excellent potential for their use as information-rich probes.

Comprehensive studies on the biological activities of human metastatic (MDA-MB-231) and non-metastatic (MCF-7) breast cancer cell lines, directly or combinedly treated using non-thermal plasma-based approaches

Progressive incidence and a pessimistic survival rate of breast cancer in women worldwide remains one of the most concerning topics. Progressing research indicates a potentially high effectiveness of use cold atmospheric plasma (CAP) systems. The undoubted advantage seems its simplicity in combination with other anti-cancer modalities. Following observed trend of studies, one inventory CAP system was applied to directly treat human breast cancer cell lines and culturing in two different Plasma Activated Media (PAM) for combined utilization. Proposed CAP treatments on MCF-10 A, MCF-7, and MDA-MB-231 cell lines were studied in terms of impact on cell viability by MTT assay. Disturbances in cell motility following direct and combined CAP application were assessed by scratch test. Finally, the induction of apoptosis and necrosis was verified with annexin V and propidium iodide staining. Reactive species generated during CAP treatment were determined based on optical emission spectrometry analysis along with colorimetric methods to qualitatively assess the NO2−, NO3−, H2O2, and total ROS with free radicals concentration. The most effective approach for CAP utilization was combined treatment, leading to significant disruption in cell viability, motility and mostly apoptosis induction in breast cancer cell lines. Determined CAP dose allows for mild outcome, showing insignificant harm for the non-cancerous MCF-10 A cell line, while the highly aggressive MDA-MB-231 cell line shows the highest sensitivity on proposed CAP treatment. Direct CAP treatment seems to drive the cells into the sensitive state in which the effectiveness of PAM is boosted. Observed anti-cancer response of CAP treatment was mostly triggered by RNS (mostly NO2− ions) and ROS along with free radicals (such as H2O2, OH•, O2-•, 1O2, HO2•). The combined application of one CAP source represent a promising alternative in the development of new and effective modalities for breast cancer treatment.

Iron oxide nanoparticles synthesized using Mentha spicata extract and evaluation of its antibacterial, cytotoxicity and antimigratory potential on highly metastatic human breast cells

Iron oxide nanoparticles (Fe2O3 NPs) were synthesized utilizing Mentha spicata sourced from Cyprus as a stabilizing agent. The study delved into assessing the antimicrobial, cytotoxic, anti-proliferative, and anti-migratory potential of Fe2O3 NPs through disc diffusion, trypan blue, and 3-[4, 5-dimethylthiazol-2-yl]−2, 5-diphenyltetrazolium bromide (MTT) assay, respectively. Characterization of the synthesized Fe2O3 NPs was conducted using Fourier-transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), UV–vis spectroscopy (UV–vis), scanning electron microscopy (SEM), and energy-dispersive x-ray spectroscopy (EDX). The FTIR, XRD, and SEM-EDX spectra confirmed the successful formation of Fe2O3 NPs. The analysis of UV–vis spectra indicates an absorption peak at 302 nm, thereby confirming both the successful synthesis and remarkable stability of the nanoparticles. The nanoparticles exhibited uniform spherical morphology and contained Fe, O, and N, indicating the synthesis of Fe2O3 NPs. Additionally, the Fe2O3 NPs formed through biosynthesis demonstrated antimicrobial capabilities against Escherichia coli and Bacillus cereus. The significant anti-migratory potential on MDA-MB 231 human breast cancer cells was observed with lower concentrations of the biosynthesized Fe2O3 NPs, and higher concentrations revealed cytotoxic effects on the cells with an IC50 of 95.7 μg/ml. Stable Fe2O3 NPs were synthesized using Mentha spicata aqueous extract, and it revealed antimicrobial activity on E. coli and B. cereus, cytotoxic, anti-proliferative and anti-migratory effect on highly metastatic human breast cancer cell lines.

Abstract 1881: Screening of Rac1 and Cdc42 inhibitors as anti-metastatic compounds

Abstract Metastasis is responsible for &amp;gt;90% of cancer-related deaths and is a key cause of failure of cancer therapy. The development of effective targeted therapy to prevent and treat metastasis has been challenging. Homologous Rho GTPases Rac and Cdc42 are viable metastasis targets because they have a crucial role in the signaling pathways that regulate cell survival, proliferation, and migration, so dysregulation of these proteins leads to cancer progression and metastasis of diverse cancer types. Therefore, targeting these regulatory proteins results in anticancer and antimetastatic activity, as observed with our dual Rac/Cdc42 inhibitor, MBQ-167, in triple-negative breast cancer. MBQ-167 has an IC50 of ~100nM for Rac and Cdc42 activation inhibition and a GI50 of 130nM. MBQ-167 inhibits the binding of guanine nucleotides to Rac and Cdc42 with similar efficacy. The purpose of this study was to identify MBQ-167 derivatives with similar or greater efficacy and specificity, with a range of inhibitory mechanisms, that may be specific to the different guanine nucleotide exchange factors expressed in distinct cancer cell types. Currently, over 30 different compounds with potential Rac1 and Cdc42 inhibitory activity are being evaluated. So far, some of the evaluated compounds have shown comparable GI50 values to MBQ-167 in metastatic breast cancer cell lines. From this screening, CPV-337 was selected as a compound with a GI50 of ~55nM and ~70% Rac activation inhibition at 50nM, therefore being 2X more effective than our leading compound MBQ-167. However, evaluation of CPV-337 in the viability of the MCF-10 non-tumorigenic epithelial cell line demonstrated a GI50 of ~63nM, which is similar to that of breast cancer cells. Therefore, CPV-337 may have cytotoxic effects on breast cancer. We are continuing to screen the library of MBQ-167 derivatives in breast, pancreatic, lung, and prostate cancer cell lines. Citation Format: Jessica Colón González, María C. Santa María Fuentes, Cornelis Vlaar, Suranganie Dharmawardhane. Screening of Rac1 and Cdc42 inhibitors as anti-metastatic compounds [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1881.

Abstract 6764: Vascularized tumor-on-chip model for evaluating chemotherapeutic-mediated damage to adjacent healthy tissue

Abstract Introduction: Systemic chemotherapy is an effective anticancer treatment for all stages of breast cancer, with intravenous (IV) infusion being the principal method of administration. In addition to targeting cancer, systemic chemotherapy can impact the viability and function of surrounding normal tissues and vasculature. Early-discovery research tools comparing novel and existing systemic treatment strategies are urgently needed to support predictive efficacy and toxicity efforts. Microfluidic systems have the potential to fill this need while simultaneously reducing animal use. The overall goal of the study is to use an advanced microfluidic tumor-on-chip system to simultaneously evaluate the therapeutic and toxic effects of IV chemotherapy on normal and cancerous tissues. Materials and Methods: Synthetic Tumor Networks, which are comprised of primary and secondary tissue sites separated by an interconnected vasculature, were developed using in vivo images and fabricated using soft lithography. Primary vascular endothelial cells were used to establish microvasculature. A normal breast cell line (MCF 10A), or a GFP-labeled metastatic human breast cancer cell line (MDA-MB-231/GFP), were cultured in the tissue sites in a three-dimensional (3D) environment using a human-derived hydrogel. The vascular networks were perfused with endothelial cell media under physiological fluid flow conditions to establish the model. An EZH2 methyltransferase inhibitor (EZH2 inhibitor III) was delivered by IV infusion to the model tissues. Real-time monitoring of cellular growth, tumor invasion and extravasation, and cellular viability were performed using fluorescence microscopy over a two-week period. Results and Discussion: Metastatic MDA-MB-231/GFP breast cancer cells proliferated rapidly in the primary tumor site. Tumor intravasation into the vascular channels was observed in models that received no anticancer treatment, as well as extravasation into the secondary tissue site and invasion of the healthy breast tissue. Differences in tumor viability and migratory behavior were observed between untreated models or models receiving IV infusions of the EZH2 inhibitor through the vascular networks. Vascular barrier integrity and normal breast tissue viability were monitored at early (24-72 hr) and late (7-14 days) timepoints after anticancer treatment to measure short- and long-term adverse drug impacts. These results provide a unique perspective on the in vivo realism of an in vitro system for monitoring both therapeutic and toxic effects of systemic chemotherapies. Conclusions: We have developed a 3D vascularized tumor-on-chip model for monitoring the impacts of systemic chemotherapeutic agents on tumor and healthy tissues. This model can be used to investigate therapeutic and toxic effects on multiple tissue types simultaneously using real-time imaging techniques. Citation Format: Deborah Ramsey, Jenna Rosano, Cristabel Gordon, Gwen Fewell. Vascularized tumor-on-chip model for evaluating chemotherapeutic-mediated damage to adjacent healthy tissue [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6764.

O-Glycome Profiling of Breast Cancer Cell Lines to Understand Breast Cancer Brain Metastasis.

Breast cancer is the second leading cause of cancer-related death among women and a major source of brain metastases. Despite the increasing incidence of brain metastasis from breast cancer, the underlying mechanisms remain poorly understood. Altered glycosylation is known to play a role in various diseases including cancer metastasis. However, profiling studies of O-glycans and their isomers in breast cancer brain metastasis (BCBM) are scarce. This study analyzed the expression of O-glycans and their isomers in human breast cancer cell lines (MDA-MB-231, MDA-MB-361, HTB131, and HTB22), a brain cancer cell line (CRL-1620), and a brain metastatic breast cancer cell line (MDA-MB-231BR) using nanoLC-MS/MS, identifying 27 O-glycan compositions. We observed significant upregulation in the expression of HexNAc1Hex1NeuAc2 and HexNAc2Hex3, whereas the expression of HexNAc1Hex1NeuAc1 was downregulated in MDA-MB-231BR compared to other cell lines. In our isomeric analysis, we observed notable alterations in the isomeric forms of the O-glycan structure HexNAc1Hex1NeuAc1 in a comparison of different cell lines. Our analysis of O-glycans and their isomers in cancer cells demonstrated that changes in their distribution can be related to the metastatic process. We believe that our investigation will contribute to an enhanced comprehension of the significance of O-glycans and their isomers in BCBM.

A novel liquid biopsy assay for detection of ERBB2 (HER2) amplification in circulating tumor cells (CTCs).

Circulating tumor cell (CTC)-based ERBB2 (HER2) assay is a laboratory test developed by Epic Sciences using single-cell genomics to detect ERBB2 (HER2) amplification in CTCs found in the peripheral blood of metastatic breast cancer (MBC) patients. Peripheral blood was collected in Streck tubes and centrifugation was used to remove plasma and red blood cells. The remaining nucleated cells were deposited on glass slides, immunofluorescent-stained with proprietary antibodies, scanned by a high-definition digital scanner, and analyzed by a proprietary algorithm. In addition, single-cell genomics was performed on selected CTC. Analytical validation was performed using white blood cells from healthy donors and breast cancer cell lines with known levels of ERBB2 amplification. Clinical concordance was assessed on MBC patients whose blood was tested by the CTC ERBB2 (HER2) assay and those results are compared to results of matched metastatic tissue biopsy (immunohistochemistry [IHC] 3+ or IHC2+/in situ hybridization [ISH+]). Epic's ERBB2 (HER2) assay detected 2-fold ERBB2 amplification with 85% sensitivity and 94% specificity. In the clinical concordance study, among the 50% of the cases that had ERBB2 status results from CTCs found to be chromosomally-unstable, the CTC ERBB2 (HER2) assay showed sensitivity of 69% and specificity of 78% when compared to HER2 status by metastatic tissue biopsy. The CTC ERBB2 (HER2) assay can consistently detect ERBB2 status in MBC cell lines and in the population of patients with MBC with detectable chromosomally unstable CTCs for whom tissue biopsy is not available or is infeasible.

Chemotherapeutics-Loaded Poly(Dopamine) Core-Shell Nanoparticles for Breast Cancer Treatment.

Chemophotothermal therapy is an emerging treatment of metastatic and drug-resistant cancer anomalies. Among various photothermal agents tested, poly(dopamine) provides an excellent biocompatible alternative that can be used to develop novel drug delivery carriers for cancer treatment. This study explores the synthesis of starch-encapsulated, poly(dopamine)-coated core-shell nanoparticles in a one-pot synthesis approach and by surfactant-free approach. The nanoparticles produced are embellished with polymeric stealth coatings and are tested for their physiologic stability, photothermal properties, and drug delivery in metastatic triple-negative breast cancer cell (TNBC) lines. Our results indicate that stealth polymer-coated nanoparticles exhibit superior colloidal stability under physiologic conditions, and are excellent photothermal agents, as determined by the increase in temperature of solution in the presence of nanoparticles, upon laser irradiation. The chemotherapeutic drug-loaded nanoparticles also showed concentration-dependent toxicities in TNBC and in a brain metastatic cell line. SIGNIFICANCE STATEMENT: This study develops, for the first time, biocompatible core-shell nanoparticles in a template-free approach that can serve as a drug delivery carrier and as photothermal agents for cancer treatment.

Low-dose decitabine enhances the efficacy of viral cancer vaccines for immunotherapy

Cancer immunotherapy requires a specific antitumor CD8+ Tcell-driven immune response; however, upon genetic and epigenetic alterations of the antigen processing and presenting components, cancer cells escape the CD8+ Tcell recognition. As a result, poorly immunogenic tumors are refractory to conventional immunotherapy. In this context, the use of viral cancer vaccines in combination with hypomethylating agents represents a promising strategy to prevent cancer from escaping immune system recognition. In this study, we evaluated the sensitivity of melanoma (B16-expressing ovalbumin) and metastatic triple-negative breast cancer (4T1) cell lines to FDA-approved low-dose decitabine in combination with PeptiCRAd, an adenoviral anticancer vaccine. The two models showed different sensitivity to decitabine invitro and invivo when combined with PeptiCRAd. In particular, mice bearing syngeneic 4T1 cancer showed higher tumor growth control when receiving the combinatorial treatment compared to single controls in association with a higher expression of MHC class I on cancer cells and reduction in Tregs within the tumor microenvironment. Furthermore, remodeling of the CD8+ Tcell infiltration and cytotoxic activity toward cancer cells confirmed the effect of decitabine in enhancing anticancer vaccines in immunotherapy regimens.

The emerging role of breast cancer derived extracellular vesicles-mediated intercellular communication in ovarian cancer progression and metastasis.

Breast cancer is one of the most occurring cancer types in women worldwide and metastasizes to several organs such as bone, lungs, liver, brain, and ovaries. Extracellular vesicles (EVs) mediate intercellular signaling which has a profound effect on tumor development and metastasis. Recent developments in the field of EVs provide an opportunity to investigate the roles of EVs released from tumor cells in metastasis. In this study, we compared the effects of metastatic breast cancer-derived EVs on both nonluteinized granulosa HGrC1 and ovarian cancer OVCAR-3 cells in terms of proliferation, invasion, apoptosis, and gene expression levels. EVs were isolated from the culture medium of metastatic breast cancer cell line MDA-MB-231 by ultracentrifugation. Cell proliferation, apoptosis, cell cycle, invasion, and cellular uptake analysis were performed to clarify the roles of tumor-derived EVs in both cells. 6.85 × 108 nanoparticles of BCD-EVs were markedly increased cell proliferation as well as invasion capacity. Exposing the cells with BCD-EVs for 24h, resulted in an accumulation of both cells in G2/M phase as determined by flow cytometry. The apoptosis assay results were consistent with cell proliferation and cell cycle results. The uptake of the BCD-EVs was efficiently internalized by both cells. In addition, marked variations in fatty acid composition between cells were observed. BCD-EVs appeared new fatty acids in HGrC1. Besides, BCD-EVs upregulated epithelial-mesenchymal transition (EMT) and proliferation-related genes. In conclusion, an environment of tumor-derived EVs changes the cellular phenotype of cancer and noncancerous cells and may lead to tumor progression and metastasis.

Abstract B105: Antineoplastic effects and expression modulations in proliferation/apoptosis related genes by riproximin in breast cancer cells

Abstract Background: Ribosomal inactivating proteins (RIPs) target the ribosomal machinery of target cells and stop the translational machinery irreversibly. Riproximin is a plant-based RIP which was extracted and purified from the plant “Ximenia americana”. Riproximin has demonstrated its anticancer effects against various in vitro and in vivo cancer models. In this study, the focus was to evaluate the effects of riproximin on proliferation and apoptosis of breast cancer cells at functional and molecular levels. Methods: MTT dye reduction assay and DAPI nuclear staining methodologies were used to highlight the riproximin mediated effects on proliferation and apoptosis in primary (MCF-7) and metastatic (MDA-MB-231) breast cancer cell lines. Afterwards, the two cell lines were used to investigate the expression modulations in genes related to PIK3/Akt and apoptosis pathways (84 genes/pathway) via real-time PCR methodology. The expression modulations were used to build the signalling pathways via Ingenuity Pathway Analysis supported by Qiagen software system. Results: Riproximin successfully halted the proliferation of the breast cancer cells with an average 50% inhibitory concentrations of 1.2 and 2.9 ng/ml after 72 hours exposure interval in MCF-7 and MDA-MB-231 cells, respectively. The protein also induced apoptotic effects in the two cell lines as reflected by shrinkage, blebbing and fragmentation of the nucleus/DNA content in a concentration dependant format. Substantial alterations (≥2fold) were observed in PIK3/Akt pathway genes (MCF-7: 49/84, MDA-MB-231: 28/84) in response to riproximin exposure. Similarly, the protein induced de-regulation (≥2fold) of apoptosis related 44/84 and 34/84 genes in MCF-7 and MDA-MB-231 cell lines, respectively. The Ingenuity Pathway Analysis revealed involvement of these genes at distinct positions in cell survival and death mechanisms. Conclusion: Riproximin demonstrated the substantial potential to induce the cytotoxic effects in breast cancer cells. The protein also de-regulated a significant number of proliferation and apoptosis related genes in breast cancer primary and metastatic cells. Further in vitro investigations are required to understand the fine molecular tuning being operated by this natural plant protein in cancer cells. Citation Format: Asim Pervaiz, Asma Khan, Kiran Umer, Martin R. Berger. Antineoplastic effects and expression modulations in proliferation/apoptosis related genes by riproximin in breast cancer cells [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr B105.

Metabolic Alterations Associated with Loss of TET2 Potentiates Inflammation in Myeloid Cells Driving Breast Cancer Progression

Clonal hematopoiesis of indeterminate potential (CHIP) is characterized by the clonal expansion of hematopoietic stem cells possessing somatic mutations commonly associated with cancer, but with no detectable hematological cancer. Certain CHIP driver mutations, such as loss of function in Tet2 result in hyperinflammatory myeloid cells. The proinflammatory cytokine IL-1β promotes breast cancer progression and correlates with disease severity. Activation of the NLRP3 inflammasome in myeloid cells is the main source of IL-1β processing. Here, we demonstrate growth of the metastatic breast cancer cell line, E0771, in both germline and chimeric Tet2 +/- mice was 2-fold greater than that observed in Tet2 +/+ mice (Figure 1). The increased tumor burden in Tet2 +/- mice was shown to be NLRP3-dependent as Tet2 +/-mice receiving the NLRP3 inhibitor, OLT1177, exhibited significantly decreased tumor growth compared to Tet2 +/- mice with no treatment (Figure 1). Cellular composition of the tumor microenvironment was also assessed. Notably, we observed marked increases in tumor-infiltrating granulocytes in the Tet2 +/- mice. This observation was consistent with elevated serum cytokines associated with neutrophil recruitment and activation. Next, considering NLRP3 inflammasome activation is tightly linked to metabolic alterations, we sought to characterize the metabolic profile of Tet2 +/- myeloid cells. To start, global metabolic analysis revealed increased abundance of metabolites from glycolysis and pentose phosphate pathway in Tet2 +/- myeloid cells compared to Tet2 +/+ myeloid cells. Consistent with the metabolic demands of a hyperinflammatory phenotype, Seahorse Flux assays revealed significantly increased ECAR (glycolysis) and OCR (pentose phosphate pathway) as measured at baseline in Tet2 +/- myeloid cells compared to Tet2 +/+ myeloid cells. Lastly, to confirm whether metabolic alterations drive the hyperinflammatory phenotype in Tet2 +/- myeloid cells, we assessed cytokine production after LPS stimulation in Tet2 +/-and Tet2 +/+ myeloid cells treated with 2-DG (glycolysis inhibitor) or 6-AN (pentose phosphate pathway inhibitor). Expectedly, Tet2 +/- myeloid cells produced significantly more IL-1β, IL-6, TNFα and IL-18 compared to Tet2 +/+ myeloid cells after LPS stimulation. LPS induced IL-1β and IL-6 production was significantly decreased for both genotypes after 2-DG and 6-AN treatment. Importantly, LPS induced TNFα and IL-18 only decreased after 2-DG and 6-AN treatment in Tet2 +/- myeloid cells suggesting metabolic changes associated with loss of TET2 affect not only NLRP3 priming but TNFα secretion as well. Overall, these studies demonstrate how TET2-driven CHIP alters the tumor microenvironment in breast cancers through aberrant NLRP3 activation and characterizes the underlying metabolic alterations subsequent to loss of TET2, offering further mechanistic insight into the hyperinflammatory phenotype in myeloid cells associated with TET2-driven CHIP. Figure 1. Tet2+/- driven breast cancer progression is NLRP3 activation-dependent. Experimental designs; BM chimeras were generated by transplanting 75%WT:25%Tet2+/+ or Tet2+/- mixed BM, mice were orthotopically implanted with E0771 breast tumors and given standard or OLT1177 diet (OLT). Tumor growth curve from Tet2+/+(WT) or Tet2 +/- chimeric mice implanted with E0771 cells receiving standard or OLT1177 diet(OLT) (N=10, two independent experiments). ***p&amp;lt;0.001, **p&amp;lt;0.01, *p&amp;lt;0.05.

Immuno-Modulatory Effects of Korean Mistletoe in MDA-MB-231 Breast Cancer Cells and THP-1 Macrophages

Korean mistletoe (Viscum album var. coloratum) has been traditionally used as a remedy for cancer, diabetes, and hypertension. This study investigated the immuno-modulatory effects of Korean mistletoe water extract, specifically on MDA-MB-231 cells, a highly metastatic breast cancer cell line, when co-cultured with THP-1 human macrophage cells. When compared to MDA-MB-231 cells cultured alone, the co-culture of MDA-MB-231/THP-1 cells treated with mistletoe extract showed a significant reduction in IL-6 secretion. Additionally, these co-cultures exhibited elevated levels of IL-4, TGF-β, and IFN-y. These results suggest that water extracts from mistletoe have the potential to induce mitochondria-targeted apoptosis in MDA-MB 231 cells stimulated by THP macrophages. Regarding apoptosis, in MDA-MB-231 cells co-cultured with THP-1 macrophages, mistletoe water extract treatment triggered a significant increase in Bax/Bcl-2 ratio, caspase-3 activation, and PARP inactivation. In addition, there was a significant increase in E-cadherin and a decrease in N-cadherin. Treatment of Korean mistletoe also led to significant reductions in both MMP-2 and -9. Furthermore, inhibition of cell migration in MDA-MB-231/THP-1 co-cultured cells was observed. In summary, this study highlights the potential of Korean mistletoe as a prospective drug for the treatment of triple-negative breast cancer, particularly through its ability to regulate human immunity.