Negative Breast Cancer Cell Lines 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.

Arene Ruthenium Complexes Specifically Inducing Apoptosis in Breast Cancer Cells

Monocationic arene ruthenium complexes (RuL1–RuL4) incorporating phenothiazinyl-hydrazinyl-thiazole ligands (L1–L4) have been synthesized, characterized and evaluated as anticancer agents. Their cytotoxicity, antiproliferative activity and alteration of apoptotic gene expression were studied on three cancer cell lines, a double positive breast cancer cell line MCF-7 and two triple negative breast cancer cell lines Hs578T and MDA-MB-231. All arene ruthenium complexes were able to reduce the viability of the breast cancer cell lines, with the highest cytotoxicities being recorded for the [(p-cymene)RuL3Cl]+ (RuL3) complex on the MCF-7 (IC50 = 0.019 µM) and Hs578T cell lines (IC50 = 0.095 µM). In the double positive MCF-7 breast cancer cells, the complexes [(p-cymene)RuL1Cl]+ (RuL1) and [(p-cymene)RuL2Cl]+ (RuL2) significantly upregulated pro-apoptotic genes including BAK, FAS, NAIP, CASP8, TNF, XIAP and BAD, while downregulating TNFSF10. In the triple negative breast cancer cell line Hs578T, RuL1 reduced TNFSF-10 and significantly upregulated BAK, CASP8, XIAP, FADD and BAD, while complex RuL2 also increased BAK and CASP8 expression, but had limited effects on other genes. The triple negative MDA-MB-231 cancer cells treated with RuL1 upregulated NOD1 and downregulated p53, while RuL2 significantly downregulated p53, XIAP and TNFSF10, with minor changes in other genes. The significant alterations in the expression of key apoptotic genes suggest that such complexes have the potential to target cancer cells.

CD81-guided heterologous EVs present heterogeneous interactions with breast cancer cells

BackgroundExtracellular vesicles (EVs) are cell-secreted particles conceived as natural vehicles for intercellular communication. The capacity to entrap heterogeneous molecular cargoes and target specific cell populations through EV functionalization promises advancements in biomedical applications. However, the efficiency of the obtained EVs, the contribution of cell-exposed receptors to EV interactions, and the predictability of functional cargo release with potential sharing of high molecular weight recombinant mRNAs are crucial for advancing heterologous EVs in targeted therapy applications.MethodsIn this work, we selected the popular EV marker CD81 as a transmembrane guide for fusion proteins with a C-terminal GFP reporter encompassing or not Trastuzumab light chains targeting the HER2 receptor. We performed high-content imaging analyses to track EV-cell interactions, including isogenic breast cancer cells with manipulated HER2 expression. We validated the functional cargo delivery of recombinant EVs carrying doxorubicin upon EV-donor cell treatment. Then, we performed an in vivo study using JIMT-1 cells commonly used as HER2-refractory, trastuzumab-resistant model to detect a more than 2000 nt length recombinant mRNA in engrafted tumors.ResultsFusion proteins participated in vesicular trafficking dynamics and accumulated on secreted EVs according to their expression levels in HEK293T cells. Despite the presence of GFP, secreted EV populations retained a HER2 receptor-binding capacity and were used to track EV-cell interactions. In time-frames where the global EV distribution did not change between HER2-positive (SK-BR-3) or -negative (MDA-MB-231) breast cancer cell lines, the HER2 exposure in isogenic cells remarkably affected the tropism of heterologous EVs, demonstrating the specificity of antiHER2 EVs representing about 20% of secreted bulk vesicles. The specific interaction strongly correlated with improved cell-killing activity of doxorubicin-EVs in MDA-MB-231 ectopically expressing HER2 and reduced toxicity in SK-BR-3 with a knocked-out HER2 receptor, overcoming the effects of the free drug. Interestingly, the fusion protein-corresponding transcripts present as full-length mRNAs in recombinant EVs could reach orthotopic breast tumors in JIMT-1-xenografted mice, improving our sensitivity in detecting penetrant cargoes in tissue biopsies.ConclusionsThis study highlights the quantitative aspects underlying the creation of a platform for secreted heterologous EVs and shows the limits of single receptor-ligand interactions behind EV-cell engagement mechanisms, which now become the pivotal step to predict functional tropism and design new generations of EV-based nanovehicles.

7274 Assessing The Interactome Of Hexose-6-Phosphate Dehydrogenase In Breast Cancer Cells And Identifying Anterior Gradient Protein 2 As Interacting Partner By Using A BioID Method

Abstract Disclosure: G. Sakalauskaite: None. M. Weingartner: None. T. Bock: None. J. Birk: None. M. Tsachaki: None. A. Odermatt: None. Hexose-6-phosphate dehydrogenase (H6PD) catalyzes the first two steps of the pentose-phosphate pathway in the endoplasmic reticulum (ER). It is so far the only enzyme shown to generate NADPH in the ER. H6PD is involved in physiological processes such as glucose and steroid metabolism, redox regulation, and response to ER-stress. So far, only one H6PD interacting partner, 11β-hydroxysteroid dehydrogenase 1 (11β-HSD1), has been reported. This enzyme uses NADPH for its well-reported role in glucocorticoid activation. However, H6PD has 11β-HSD1-independent functions, such as the recently described modulation of breast cancer cell properties. Here, we adapted the BioID approach to identify novel H6PD interacting partners in the ER. First, we generated a triple negative breast cancer cell line MDA-MB 231 stably expressing a H6PD-biotin ligase fusion protein. Then, we validated the method to confirm the known interaction between H6PD and 11β-HSD1. Next, we analyzed enriched biotinylated proteins by mass spectrometry and further assessed potential candidates by co-immunoprecipitation and functional assays. The resulting interactome revealed a potential hit cluster of protein disulfide isomerase (PDI) family members, different ER-resident chaperones and luminal calcium binding proteins. Due to its association with breast cancer, we further examined the PDI Anterior gradient protein 2 (AGR2) as H6PD interacting partner. Physical interaction between AGR2 and H6PD was confirmed by co-immunoprecipitation assay in MCF7 cells. Downregulation of AGR2 by siRNA resulted in elevated H6PD protein levels but decreased activity. Furthermore, increased H6PD activity was observed when this protein was co-expressed with AGR2 in HEK-293 cells. In conclusion, the results validated the use of the BioID approach to identify protein interactions within the ER and they revealed that AGR2 physically interacts with H6PD, thereby controlling its expression and enzyme activity. Presentation: 6/3/2024

8817 IGF-II Regulates Magmas A Mitochondrial Protein Required For Cell Viability And ROS Protection

Abstract Disclosure: K. Granados: None. A. Durán: None. F. Almaguel: None. D. De Leon: None. Our laboratory previously showed that Insulin-like growth factor II (IGF-II) promotes cell proliferation, inhibits apoptosis and induces chemoresistance of Breast Cancer (BC) cells. We demonstrated that IGF-II achieves this by inhibiting pro-apoptotic proteins and stimulating anti-apoptotic proteins. Those studies also demonstrated that IGF-II prevented mitochondrial induced apoptosis by inhibiting depolarization of the mitochondrial membrane. Thus, IGF-II regulates the mitochondria to prevent cell death and to promote tumor growth and chemoresistance. Since IGF-II regulates mitochondrial proteins, we decided to assess how IGF-II regulates MAGMAS, a protein located in the inner mitochondrial membrane that is a critical component of a complex that controls mitochondrial protein import and ROS. Of note, MAGMAS was recently identified as being highly expressed in breast cancer, prostate cancer and during early fetal development which parallels IGF-II expression. Immunostaining of TNBC showed high levels of IGF-II and MAGMAS. Thus, our hypothesis is that IGF-II regulates MAGMAS and IGF-II secreting breast cancer cells will express higher levels of MAGMAS. Our preliminary results of rtPCR and Western blotting experiments validated our hypothesis demonstrating that IGF-II regulated the transcription of MAGMAS. To characterize the mechanisms by which IGF-II regulates MAGMAS, we chose the triple negative breast cancer (TNBC) cell line CRL-2335 which we demonstrated produces high levels of IGF-II and MAGMAS. CRL2335 cells were established from an AA TNBC patient and they express high levels of IGF-II and MAGMAS. Confocal microscopy and Western blotting and cellular fractionation were used to assess IGF-II regulation of MAGMAS in TNBC cells. The expression of MAGMAS was analyzed in wild CRL-2335, and IGF-II antisense transfected CRL-2335 cells and compared to cells treated with IGF-II. Results showed that CRL-2335 express high levels of MAGMAS in the mitochondria and blocking the expression of IGF-II by antisense technology significantly decreased MAGMAS. Exogenous IGF-II treatment to the antisense cells increased MAGMAS as demonstrated by Immunofluorescence and WB. Since IGF-II increases the localization of MAGMAS to the mitochondria we propose that IGF-II regulates MAGMAS to protect cancer cells from ROS induced cell death and chemoresistance. Completion of this study will validate IGF-II as a regulator of MAGMAS. Validation of IGF-II regulation of MAGMAS represents an important new tool for the treatment of TNBC. Presentation: 6/2/2024

Discovery and optimization of anthraquinone derivatives containing substituted bisbenzyloxy groups as a novel scaffold damaged endoplasmic reticulum and against hepatocellular carcinoma cells

This paper reports the antitumor activity and possible mechanism of anthraquinone derivatives containing substituted bisbenzyloxy groups. Series of anthraquinone derivatives containing substituted bisbenzyloxy groups were designed and synthesized by etherification and esterification. The antitumor activities of the synthesized substituted bisbenzyloxy anthraquinone derivatives on liver cancer cell Huh7, triple negative breast cancer cell line MDA-MB-231 and lung cancer cell A549 were in the order of methoxy substitution > methyl substitution > chloral substitution. Among these, the Compound KA-MO-g showed strong antitumor activity, especially against liver cancer Huh7 cells. Further studies on the antitumor mechanism showed that the Compound KA-MO-g simultaneously activated three pathways of endoplasmic reticulum stress (ERS), also caused impairment of endoplasmic reticulum (ER) functions, such as glycoprotein synthesis and disulfide bond formation are impeded and caused calcium overload,then increased mitochondrial ROS, damaged of mitochondria, changed of apoptosis-related protein levels, activated Caspase 3, induced the apoptosis of Huh7 cells. Because KA-MO-g showed strong antitumor activity, it is expected to be a new candidate drug for treating liver cancer and is worth further study.

Magnetically Integrated Tumor-Vascular Interface System to Mimic Pro-angiogenic Endothelial Dysregulations for On-Chip Drug Testing.

The tumor-vascular interface is a critical component of the tumor microenvironment that regulates all of the dynamic interactions between a growing tumor and the endothelial lining of the surrounding vasculature. In this paper, we report the design and development of a custom-engineered tumor-vascular interface system for investigating the early stage tumor-mediated pro-angiogenic dysfunctional behavior of the endothelium. Using representative endothelial cells and triple negative breast cancer cell lines, we established a biomimetic interface between a three-dimensional tumor tissue across a mature, functional endothelial barrier using a magnetically hybrid-integrated tumor-vascular interface system, wherein vasculature-like features containing a monolayer of endothelial cell culture on porous microfluidic channel surfaces were magnetically attached to tumor spheroids generated on a composite polymer-hydrogel microwell plate and embedded in a collagen matrix. Tumor-mediated endothelial microdynamics were characterized by their hallmark behavior such as loss of endothelial adherens junctions, increased cell density, proliferation, and changes in cell spreading and corroborated with endothelial YAP/TAZ nuclear translocation. We further confirm the feasibility of drug-mediated reversal of this pro-angiogenic endothelial organization through two different signaling mechanisms, namely, inhibition of the vascular endothelial growth factor pathway and the Notch signaling pathway, thereby demonstrating the utility of the tumor-vascular interface platform for rapid, early stage prediction of antiangiogenic drug efficacy. Overall, our work emphasizes the importance of our strategic engineering approach for identifying some unique, physiologically relevant aspects of the tumor-vascular interface, which are otherwise difficult to implement using standard in vitro approaches.

Neratinib plus dasatinib is highly synergistic in HER2-positive breast cancer in vitro and in vivo

BackgroundHER2-targeted therapies have revolutionised the treatment of HER2-positive breast cancer. However, de novo resistance or the emergence of acquired resistance is a persistent clinical problem. Here we report that neratinib, an irreversible pan-HER inhibitor, in combination with the multi-kinase inhibitor dasatinib, currently used to treat certain leukemias, has strong anti-proliferative effects against models of HER2-positive breast cancer that are innately resistant to trastuzumab or have acquired resistance to neratinib. MethodsNeratinib plus dasatinib was examined in a panel of 20 breast cancer cell lines, including HER2-positive, estrogen-receptor-positive, triple negative, and acquired HER2-targeted therapy resistant models. Drug effects on migration and apoptosis induction was evaluated and signaling alterations were determined by reverse phase protein array (RPPA). In vivo efficacy was examined using orthotopically-implanted HCC1954 cells. ResultsSynergy was observed in cell lines innately resistant to trastuzumab, models with acquired resistance to neratinib, and in triple negative breast cancer cell lines. Further investigation showed that neratinib plus dasatinib induced apoptosis and inhibited cell migration to a greater degree than either drug alone. RPPA revealed that the combination caused suppression of key survival signaling through EGFR, Akt, and MAPK inhibition. In vivo, neratinib plus dasatinib was well tolerated and had a prolonged anti-tumor effect against HCC1954 xenografts. ConclusionsThis study provides a strong pre-clinical rationale for the clinical investigation neratinib and dasatinib in HER2+ breast cancer.

Structural, optical, antibacterial, antifungal, and anticancer activity of sodium alginate-pluronic-F127-tin dioxide nanoparticles prepared via microwave-assisted green process

The green synthesis of inorganic metal oxide nanoparticles is essential because it reduces environmental impact and enhances biocompatibility by using eco-friendly materials and processes. This sustainable approach also minimizes hazardous chemicals, promoting safer and cleaner production methods. The sodium alginate-Pluronic F127-modified SnO2 (SAPFSO) NPs were prepared using the green method using Psidium guajava leaf extract. The SAPFSO NPs exhibit a tetragonal rutile structure from the X-ray diffraction patterns. The FESEM and EDAX spectra identified the morphology and chemical composition. The Sodium Alginate, Pluronic-F127, and SnO2 functional group vibrations can be seen in the FTIR spectra. The DLS spectra and hydrodynamic sizes of SAPFSO NPs were observed at 183 nm. The various surface defects of SAPFSO NPs were identified from the PL spectrum. The antimicrobial activity of SAPFSO NPs was tested against gram-positive and gram-negative strains such as S. aureus, K. pneumoniae, S. dysenteriae, S. pneumoniae, Bacillus megaterium, Proteus valgaris, and Candida albicans fungal strain using the well-diffusion method. To increase the concentration, SAPFSO NPs also increased the antimicrobial activity. The anticancer activity of SAPFSO NPs tested against the human breast cancer cell line (MDA-MB-237). SAPFSO NPs exhibits potential anticancer activity against triple negative breast cancer cell line. These results support that SAPFSO NPs can be applied in healthcare and industrial settings to improve human health.

Acetalax (Oxyphenisatin Acetate, NSC 59687) and Bisacodyl Cause Oncosis in Triple-Negative Breast Cancer Cell Lines by Poisoning the Ion Exchange Membrane Protein TRPM4.

Acetalax and bisacodyl kill cancer cells by causing oncosis following poisoning of the plasma membrane sodium transporter TRPM4 and represent a new therapeutic approach for TNBC.

BET-directed PROTACs in triple negative breast cancer cell lines MDA-MB-231 and MDA-MB-436

PurposeThis study aims to find whether the proliferation and migration of triple negative breast cancer (TNBC) cell lines can be reduced by treatment with bromodomain and extra-terminal domain (BET) inhibitor JQ1 and BET protein targeting chimeras (PROTACs) ARV-771 and MZ1.MethodsCytotoxicity tests, scratch migration assays and western blot proteome profiler arrays for protein expression of cancer-related proteins were used to evaluate the impact of a BET-inhibitor and two BET-directed PROTACs on cell viability, migration and on protein expression.ResultsJQ1 and the PROTACs MZ1 and ARV-771 significantly inhibited the growth and migration of the KRAS G13D-mutated MDA-MB-231 cells. In this cell line, the PROTACs suppressed the residual expression of ERBB2/HER2, 3 and 4 that are essential for the proliferation of breast cancer cells and this cell line proved sensitive to HER2 inhibitors. In contrast, the effects of the PROTACs on the protein expression of MDA-MB-436 cells mostly affected cytokines and their cognate receptors.ConclusionThe degradation of BET-protein by PROTACs demonstrated significant anti-proliferative effects. The KRAS-mutated MDA-MB-231 cells belong to the low-HER2 expressing tumors that have a poorer prognosis compared to HER2-null patients. Since first oral PROTACs against tumor hormone receptors are in clinical trials, this mode of tumor therapy is expected to become an important therapeutic strategy in the future treatment of TNBC.

Evaluation of molecular effects associated with apoptosis, tumour progression, angiogenesis and metastasis by a novel combination of drugs with ormeloxifene in triple negative breast cancer cells.

To investigate the molecular effects of a novel combination [sertraline and plumbagin (comb) with ormeloxifene (Orm)] for anticancer activity in triple negative breast cancer cell line "MDA-MB-231". The cytotoxic effect of the drugs was analyzed by the MTT assay and nuclear morphological changes by acridine orange/ethidium bromide (AO/EB) staining. Induction of apoptosis by annexin V-FITC staining, active caspase-3 detection and cell cycle analysis were studied in vitro on "MDA-MB-231" cells. The qRT-PCR was done to explore the upregulation and down regulation of targeted genes for angiogenesis, metastasis, tumor suppression and protein folding on the triple negative breast cancer cells. The preliminary anti-angiogenic effect of the drugs was assessed by chorioallantoic membrane (CAM) assay. Orm showed inhibitory effects in "MDA-MB-231" cells in a dose and time dependent manner whereas; the drugs in combination gave better cytotoxic effects in the screening MTT assay. Orm + comb was more effective than Orm alone in eliciting apoptosis as well as inhibited the single cell to grow into a colony. CAM assay using Orm and Orm + comb suggested the anti-angiogenic potential which was further confirmed by the downregulation of VEGF in "MDA-MB-231" cells by qRT-PCR studies. The combination was found to effectively upregulate the expression of P53 and P21 and downregulate the gene expression of zinc finger E-box binding homeobox 1 (ZEB1) and heat shock protein 70 (HSP70) in "MDA-MB-231" cancer cells. Collectively this study reveals the efficacy of Orm + comb as more significant than the clinically used tamoxifen (Tam). The study elucidates the promising novelty of the combination as a potential chemotherapeutic intervention for mitigating the aggressiveness of triple negative breast cancer and it addresses the intrinsic resistance caused by single drug treatments.

PI3K inhibitor “alpelisib” alleviates methotrexate induced liver injury in mice and potentiates its cytotoxic effect against MDA-MB-231 triple negative breast cancer cell line

Hepatotoxicity is the main off-target effect of methotrexate (MTX) limiting its effective clinical use. Besides, MDA-MB231 breast cancer cells show chemoresistance, partly via PI3K/AKT pathway. Therefore, we investigated the ameliorative potentials of the PI3K inhibitor, alpelisib (ALP) on MTX-induced hepatotoxicity (in vivo) and the restraining potentials of ALP on MDA-MB231 chemoresistance to MTX (in vitro). Twenty-eight male BALB/c mice were divided into 4 groups. In treatment groups, mice were administered ALP (2.5 and 5 mg/kg) for 5 days and MTX (20 mg/kg) from day 2 till day 5. The results showed that ALP restored hepatic architecture, reduced immune cell infiltration (F4/80, Ly6G and MPO) and repressed the rise in liver enzymes (AST and ALT) induced by MTX. Additionally, ALP rectified the MTX-induced disruption of cellular oxidant status by boosting antioxidant defense systems (HO-1 and GSH) and repressing lipid peroxidation (MDA and 4-HNE). Finally, ALP curbed MTX-induced hepatocyte apoptosis (NF-κB and BAX) and shifted the cytokine milieu away from inflammation (IL-17, IL-22, IL-6 and IL- 10). The results of the in vitro experiments revealed that ALP alone and in combination with MTX, synergistically, reduced cancer cell viability (MTT assay), migration (wound healing assay) and their capacity to establish colonies (colony formation assay) as compared to MTX alone. RT-PCR revealed the antiproliferative (Bcl-2) and proapoptotic (BAX) potentials of ALP and ALP/MTX combination especially after 24 h. In conclusion, targeting PI3K/AKT pathway is a promising strategy in triple negative breast cancer patients by ameliorating hepatotoxicity and restraining chemoresistance to chemotherapy.

Laminin I mediates resistance to lapatinib in HER2-positive brain metastatic breast cancer cells in vitro

The role of extracellular matrix (ECM) prevalent in the brain metastatic breast cancer (BMBC) niche in mediating cancer cell growth, survival, and response to therapeutic agents is not well understood. Emerging evidence suggests a vital role of ECM of the primary breast tumor microenvironment (TME) in tumor progression and survival. Possibly, the BMBC cells are also similarly influenced by the ECM of the metastatic niche; therefore, understanding the effect of the metastatic ECM on BMBC cells is imperative. Herein, we assessed the impact of various ECM components (i.e., Tenascin C, Laminin I, Collagen I, Collagen IV, and Fibronectin) on brain metastatic human epidermal growth factor receptor 2 (HER2)-positive and triple negative breast cancer (TNBC) cell lines in vitro. The highly aggressive TNBC cell line was minimally affected by ECM components exhibiting no remarkable changes in viability and morphology. On the contrary, amongst various ECM components tested, the HER2-positive cell line was significantly affected by Laminin I with higher viability and demonstrated a distinct spread morphology. In addition, HER2-positive BMBC cells exhibited resistance to Lapatinib in presence of Laminin I. Mechanistically, Laminin I-induced resistance to Lapatinib was mediated in part by phosphorylation of Erk 1/2 and elevated levels of Vimentin. Laminin I also significantly enhanced the migratory potential and replicative viability of HER2-positive BMBC cells. In sum, our findings show that presence of Laminin I in the TME of BMBC cells imparts resistance to targeted therapeutic agent Lapatinib, while increasing the possibility of its dispersal and clonogenic survival.

PAK6 acts downstream of IQGAP3 to promote contractility in triple negative breast cancer cells

Breast cancer is a heterogeneous disease that remains the most common malignancy among women worldwide. During genomic analysis of breast tumours, mRNA levels of IQGAP3 were found to be upregulated in triple negative tumours. IQGAP3 was subsequently found to be expressed across a panel of triple negative breast cancer (TNBC) cell lines. Depleting expression levels of IQGAP3 delivered elongated cells, disrupted cell migration, and inhibited the ability of cells to form specialised invasive adhesion structures, termed invadopodia. The morphological changes induced by IQGAP3 depletion were found to be dependent on RhoA. Indeed, reduced expression of IQGAP3 disrupted RhoA activity and actomyosin contractility. Interestingly, IQGAP3 was also found to interact with p-21 activated kinase 6 (PAK6); a protein already associated with the regulation of cell morphology. Moreover, PAK6 depletion phenocopied IQGAP3 depletion in these cells. Whereas PAK6 overexpression rescued the IQGAP3 depletion phenotype. Our work points to an important PAK6-IQGAP3-RhoA pathway that drives the cellular contractility of breast cancer cells promoting both cell migration and adhesive invasion of these cells. As this phenotype is relevant to the process of metastasis and re-seeding of metastasis, the pharmacological targeting of PAK6 could lead to clinical benefit in TNBC patients.

Design, synthesis and evaluation of thieno[3,2-d]pyrimidine derivatives as novel potent CDK7 inhibitors

The targeting of cyclin-dependent kinase 7 (CDK7) has become a highly desirable therapeutic approach in the field of oncology due to its dual role in regulating essential biological processes, encompassing cell cycle progression and transcriptional control. We have previously identified a highly selective thieno[3,2-d]pyrimidine-based CDK7 inhibitor with demonstrated efficacy and safety in animal model. In this study, we sought to optimize the thieno[3,2-d]pyrimidine core to discover a novel series of CDK7 inhibitors with improved potency and pharmacokinetic (PK) properties. Through extensive structure–activity relationship (SAR) studies, compound 20 has emerged as the lead candidate due to its potent inhibitory activity against CDK7 and remarkable efficacy on MDA-MB-453 cells, a representative triple negative breast cancer (TNBC) cell line. Furthermore, 20 has demonstrated favorable oral bioavailability and exhibited highly desirable pharmacokinetic (PK) properties, making it a promising lead candidate for further structural optimization.

Effects of Garlic on Breast Tumor Cells with a Triple Negative Phenotype: Peculiar Subtype-Dependent Down-Modulation of Akt Signaling.

Breast cancer includes tumor subgroups with morphological, molecular, and clinical differences. Intrinsic heterogeneity especially characterizes breast tumors with a triple negative phenotype, often leading to the failure of even the most advanced therapeutic strategies. To improve breast cancer treatment, the use of natural agents to integrate conventional therapies is the subject of ever-increasing attention. In this context, garlic (Allium sativum) shows anti-cancerous potential, interfering with the proliferation, motility, and malignant progression of both non-invasive and invasive breast tumor cells. As heterogeneity could be at the basis of variable effects, the main objective of our study was to evaluate the anti-tumoral activity of a garlic extract in breast cancer cells with a triple negative phenotype. Established triple negative breast cancer (TNBC) cell lines from patient-derived xenografts (PDXs) were used, revealing subtype-dependent effects on morphology, cell cycle, and invasive potential, correlated with the peculiar down-modulation of Akt signaling, a crucial regulator in solid tumors. Our results first demonstrate that the effects of garlic on TNBC breast cancer are not unique and suggest that only more precise knowledge of the mechanisms activated by this natural compound in each tumor will allow for the inclusion of garlic in personalized therapeutic approaches to breast cancer.

New mono and dinuclear half-sandwiched organoruthenium(II) complexes: Effect of dinuclearity on the biomolecular interaction and cytotoxicity

The present work describes the syntheses and structural characterization of new half sandwiched mono (complex 1) and dinuclear (complex 2) organoruthenium complexes derived from thiosemicarbazone ligand (L1). The molecular structures of compounds were characterized by analytical and multispectroscopic methods which corroborate well with single crystal XRD studies. DFT and TD-DFT studies of compounds revealed that HOMO electron density in L1 is localised on the thiosemicarbazide moiety while the LUMO electron density is evenly distributed over the ligand. However, in complex 1, the HOMO and LUMO is localised on the arene moiety and partially distributed over metal ion while HOMO and LUMO in complex 2 is equally delocalised throughout the complex. The collaborative preliminary DNA binding studies revealed that complexes 1 and 2 exhibited intercalative mode of interaction. The magnitude of DNA binding strength was determined by calculating Kb, K and Ksv values which demonstrated higher DNA binding propensity of complex 2. Furthermore, HSA binding studies of complexes also revealed better binding efficiency of dinuclear complex in contrast to mononuclear complex. The cytotoxic potential of dinuclear complex 2 was examined against triple negative breast cancer cell lines (MDA-MB-468 and MDA-MB-231) via MTT assay.

Abstract PO4-28-05: Prolactin drives labile iron transfer from macrophages to breast cancer cells through CD44

Abstract Cancer cells are “ferrophilic” and exhibit great dependence on iron. While iron metabolism is closely related to tumor development, the source of iron and the mechanisms cancer cells adopt to actively acquire iron is not well understood. In the present study, we discovered a novel function of the lactating hormone, prolactin, in the regulation of iron transport. In breast cancer cells using mouse triple negative breast cancer cell lines EO771 and Py230 for demonstration, prolactin stimulation increased intracellular labile iron pool. Analyses of gene expression involved in iron transport revealed dramatic induction of CD44, a surface receptor for iron bound hyaluronan. Other genes involved in iron uptake including transferrin receptor (TFRC), CD163 and divalent metal transporter 1 (DMT1) were not changed. The utilization of neutralizing antibodies against CD44 significantly blocked prolactin mediated labile iron pool accumulation in breast cancer cells. In contrast to what was found in breast cancer cells, prolactin had the opposite impact on immune macrophages. Prolactin treatment increased ferroportin (FPN I, iron exporter) but had no influence on all iron uptake transporters leading to net iron release by macrophages. To further determine if the iron released by macrophages can be a direct source of iron utilized by breast cancer cells, we conducted co-culture work of macrophages with pre-stained labile iron pool and breast cancer cells without any iron staining and found a gradual increase of fluorescent iron pool developed in breast cancer cells over time. In conclusion, our work presents a multidisciplinary regulation of iron transport among prolactin, macrophages, and cancer cells. The novel regulatory role of prolactin to drive iron flow can provide new information on fine-tuning immune responses in tumor microenvironment and potentially benefit the development of novel therapeutics. Citation Format: Reagan Farrell, Nicholas Pascuzzi, Yi-Ling Chen, Miguel Torres, Mary Kim, Lauren Gollahon, Kuan-Hui Chen. Prolactin drives labile iron transfer from macrophages to breast cancer cells through CD44 [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-28-05.

Abstract PS15-02: A Phase Ⅰb Study of D-0502 as Monotherapy for Advanced or Metastatic ER-Positive and HER2-Negative Breast Cancer: Results from the Dose-Expansion Stage

Abstract Background: Endocrine therapy is the mainstay treatment for estrogen receptor (ER)-positive advanced breast cancer (BC). D-0502, an orally bioavailable selective estrogen receptor degrader (SERD), has previously demonstrated antitumor activity in various ER-positive (ER+) and human epidermal growth factor receptor 2 negative (HER2-) breast cancer cell lines and xenograft models. The phase Ⅰ open-label study (NCT03471663) evaluated the safety, tolerability, pharmacokinetics (PK) and efficacy of D-0502 as monotherapy and in combination with palbociclib in female patients with ER+ and HER2- breast cancer. The dose escalation part of D-0502 monotherapy (phase Ⅰa) has been presented before (SABCS 2021, PS11-26 Abstract #1348). Here, we present the results of D-0502 monotherapy from the dose-expansion stage in phase Ⅰb study. Methods: In the single-agent dose-expansion stage of phase Ⅰb study, patients (n=60) received D-0502 (400 mg QD) in 28-day cycles. Eligible patients included females with confirmed ER+, HER2- locally advanced, or metastatic BC; ECOG 0-1; measurable disease (RECIST v1.1); premenopausal or postmenopausal status; adequate hematologic, hepatic and renal functions. The primary objectives are to characterize the safety of D-0502. The secondary objectives are to evaluate the preliminary anti-tumor activity and the PK characteristic. Results: As of April 07, 2023, 60 female patients were enrolled and treated with 400mg single-agent D-0502. Median age was 57 (range: 32-82) years, 55.0% had an ECOG PS of 1. Disease progression resulting in treatment discontinuation occurred in 66.7% (40/60) of patients, and 6.7% (4/60) of patients discontinued treatment because of AEs. Treatment-related adverse events (TRAEs) were reported in 57 pts (95.0%), most of which were grade 1-2. No grade 4/5 TRAE has been reported. The incidence of serious adverse events was 6.7% (4/60). The most common (≥ 15%) TRAEs included vomiting, dizziness, nausea, increased aspartate aminotransferase and alanine aminotransferase, anaemia, decreased appetite, diarrhoea, and malaise. In the 51 efficacy evaluable patients, 8 patients had partial response (PR) and 27 had stable disease (SD); objective response rate (ORR) and disease control rate (DCR) were 15.7% (8/51) and 68.6% (35/51), respectively. The clinical benefit rate (CBR: CR + PR + SD ≥24 weeks) was 47.1% (24/51). The median PFS was 5.6 months (95% Cl: 2.0, 10.0). Conclusion: D-0502 monotherapy showed promising antitumor activity and tolerable toxicity in female patients with ER+ and HER2- locally advanced or metastatic BC. Currently this treatment is being evaluated in a phase Ⅲ study for patients with ER+ and HER2- locally advanced or metastatic BC in China. Citation Format: Jiayu Wang, Tao Sun, Qingyuan Zhang, Yanxia Shi, Xu Wang, Yiding Chen, Quchang Ouyang, Kunyan Li, Manojkumar Bupathi, w. Jeffery Edenfield, Andrea L.M. Silber, Hong Zong, Erika Hamilton, Dejan Juric, Kate Lathrop, Yihong Zhang, Kathryn Stazzone, Zhe Shi, Yaolin Wang, Ling Zhang, Binghe Xu. A Phase Ⅰb Study of D-0502 as Monotherapy for Advanced or Metastatic ER-Positive and HER2-Negative Breast Cancer: Results from the Dose-Expansion Stage [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PS15-02.