Drug-resistant Breast Cancer Cells Research Articles

Ionizable Drugs Enable Intracellular Delivery of Co-Formulated siRNA.

Targeting complementary pathways in diseases such as cancer can be achieved with co-delivery of small interfering ribonucleic acid (siRNA) and small molecule drugs; however, current formulation strategies are typically limited to one, but not both. Here, ionizable small molecule drugs and siRNA are co-formulatedin drug-rich nanoparticles. Ionizable analogs of the selective estrogen receptor degrader fulvestrant self-assemble into colloidal drug aggregates and cause endosomal disruption, allowing co-delivery of siRNA against a non-druggable target. siRNA is encapsulated in lipid-stabilized, drug-rich colloidal nanoparticles where the ionizable lipid used in conventional lipid nanoparticles is replaced with an ionizable fulvestrant analog. The selection of an appropriate phospholipid and formulation buffer enables endocytosis and potent reporter gene knockdown in cancer cells. Importantly, siRNA targeting cyclin E1 is effectively delivered to drug-resistant breast cancer cells, demonstrating the utility of this approach. This strategy opens the possibility of using ionizable drugs to co-deliver RNA and ultimately improve therapeutic outcomes.

New Mitochondria-Targeted Fisetin Derivative Compromises Mitophagy and Limits Survival of Drug-Induced Senescent Breast Cancer Cells.

Mitochondria are considered as promising targets for cancer treatment. In the present study, triphenyl phosphonium cationic group-conjugated fisetin (mito-fisetin) was synthesized, and its anticancer activity was investigated in several cellular models of estrogen receptor (ER)-positive breast cancer in vitro and in vivo in proliferating and tamoxifen-promoted senescent states. Mito-fisetin, when used at low micromolar concentrations, stimulated the dissipation of mitochondrial membrane potential and oxidative stress, and affected mitochondrial function, resulting in apoptosis induction in senescent breast cancer cells. Mito-fisetin-mediated cytotoxicity was due to increased levels of phosphorylated AMPK, decreased levels of AKT and HSP90, and impaired mitophagic response, as judged by the analysis of the markers of mitophagosome formation. Senescent breast cancer cells were found to be more sensitive to mito-fisetin treatment than proliferating ones. We postulate that mitochondrial targeting in the case of fisetin may be considered as a promising anticancer and senotherapeutic strategy to eliminate drug-resistant senescent breast cancer cells.

Safe, simple and multifunctional hydroxyapatite nanoparticles for efficient overcoming of tumor multidrug resistance

Multidrug resistance (MDR) of cancer is the most common obstacle to chemotherapy. Many complex multifunctional nanoparticles have been developed for combination of two or more therapeutics to overcome MDR. Unlike these sophisticated nanoparticles, hydroxyapatite nanoparticles (HAPNs) were found to be able to inhibit cell proliferation of various human cancer cells. Herein, with different MDR cells and chemotherapeutic drugs, we tested whether HAPNs can be widely applied in fighting cancer drug resistance. Rod-shaped HAPNs were synthesized by the aqueous precipitation and then successfully loaded with paclitaxel (PTX) and doxorubicin (DOX) by physical adsorption to obtain pH-responsive drug-loaded nanoparticles, PHAPNs and DHAPNs, respectively. Plain HAPNs exhibited selective cytotoxicity to drug-resistant breast cancer cells MCF-7/ADR, lung cancer cells H69AR and A549/PTX, while spared normal human liver cells L-02. HAPN treatment led to an increase in the apoptosis ratio, a decrease in cell viability and a sustained increase in intracellular calcium ion level in MDR cells. Furthermore, HAPNs facilitated the delivery and accumulation of both drugs, thereby improving the DOX-induced DNA damage in H69AR cells, as well as the acetylation of α-tubulin and cell cycle arrest led by PTX in MCF-7/ADR and A549/PTX cells. Drug-loaded HAPNs greatly enhanced mitochondrial damage, inhibited ATP synthesis and efflux pump activity, and triggered both the intrinsic and extrinsic apoptosis induced by HAPNs or drugs alone. HAPNs acted synergistically with DOX and PTX, resulting in a >6-fold reduction in the IC50 compared with free drugs for these MDR cells. Notably, PHAPNs successfully suppressed the tumor growth in A549/PTX xenograft mice and exhibited excellent biocompatibility in vivo. These findings demonstrated that HAPNs may be widely utilized to reverse the resistance of various drug-resistant cells, providing a simple but practical approach to overcome MDR of cancer.

Self-assembling peptides induced by eyes absent enzyme to boost the efficacy of doxorubicin therapy in drug-resistant breast cancer cells

Enzyme-induced self-assembly (EISA) is a recently developed nanotechnology technique in which small molecules are induced by cellular enzymes self-assembling into nanostructures inside cancer cells. This technique can boost the efficacy of chemotherapy drugs by avoiding drug efflux, inhibiting the cells’ DNA repair mechanisms, and targeting the mitochondria. In this work, we study the self-assembly of a short peptide and its fluorescence analogue induced by Eyes absent (EYA) tyrosine phosphatases to boost the efficacy of doxorubicin (DOX) therapy in drug-resistant types of breast cancer cells, MDA-MB-231 and MCF-7. The peptides Fmoc–FF–YP and NBD–FF–YP were synthesized with the solid-phase peptide synthesis (SPPS) method and analyzed with HPLC and MALDI-TOF. Dynamic light scattering was used to determine the size distribution of peptides exposed to the EYA enzyme in vitro. The presence of EYA enzymes in breast cancer cells was confirmed using the western blotting assay. The intracellular location of the peptide self-assembly was studied by imaging fluorescence NBD-tagged peptides. The efficacy of the peptide alone and with DOX was determined against MCF-7 and MDA-MB-231 using MTT and LIVE-DEAD assays. Nucleus and cytoplasm F-actin (Phalloidin) staining was used to determine cell morphology changes in response to the combination therapy of peptides/DOX. At an optimal concentration, the peptides are not toxic to the cells; however, they boost the efficacy of DOX against drug-resistant breast cancer cells. We used state-of-the-art computer-aided techniques to predict the molecular structure of peptides and their interactions with EYA. This study demonstrates an approach for incorporating non-cytotoxic components into DOX combination therapy, thereby avoiding increased systemic burden or adverse effects.

Abstract PO3-27-02: A novel PTK6 PROTAC degrader induces apoptosis of drug resistant breast cancer cells

Abstract Background. PTK6/Brk, a non-receptor tyrosine kinase, is an oncogenic driver for several tumor types, including breast, prostate, liver, and pancreatic cancers. PTK6 is expressed in all breast cancer subtypes and higher levels of expression are associated with worse patient outcomes. The optimal approach to targeting PTK6 for therapeutic benefit has not been established. Although several inhibitors of PTK6 kinase activity have been developed, none have thus far been successfully translated to clinical trials. This may be in part due to kinase activity-independent functions of PTK6, for which there is growing evidence, that are not effectively targeted by traditional small molecule kinase inhibitors. Downregulation of PTK6 using shRNA inhibits growth, invasion/migration, survival and metastasis of breast cancer cells, including those that are resistant to standard therapies. PTK6 kinase inhibitor treatment phenocopies effects of PTK6 downregulation with respect to some, but not all PTK6-driven oncogenic activities. Moreover, growth of PTK6 CRISPR-targeted cells can be rescued either with wild type or catalytically inactive PTK6, supporting kinase activity-independent activities of PTK6 in regulating growth and viability of breast cancer cells. Therefore, PROTAC degraders may be a better way to chemically target and downregulate PTK6 expression in cancer, thereby phenocopying the effects of PTK6 shRNA. Methods. We developed a first-in-class PTK6 degrader using PROTAC (proteolysis-targeting chimeric) technology to target PTK6 expression in breast cancer cells of diverse subtypes. Degrader controls were also synthesized to assess specificity of MS105’s effects. Results. PTK6 degrader, but not degrader controls, potently downregulates PTK6 expression in multiple breast cancer cell types. Proteomic and kinome profiling confirm the specificity of our PTK6 degrader. PTK6 PROTAC degrader inhibits viability and induces apoptosis of PTK6-expressing breast cancer cells, whereas treatment with parent kinase inhibitor or degrader controls that do not engage PTK6 or E3 ligase have minimal effect. Treatment with PTK6 degrader, but not kinase inhibitor or degrader controls, induces expression of pro-apoptotic Bim, phenocopying the effects observed with PTK6 shRNA. In contrast, PTK6 degrader and kinase inhibitor are comparably effective in inhibiting cell migration, supporting the differential kinase dependency of PTK6-dependent oncogenic functions. Therefore, our PTK6 PROTAC degrader effectively inhibits both kinase-dependent and independent oncogenic activities of PTK6. Our studies support the development of PTK6 PROTAC degraders as a preferred approach to clinically targeting PTK6 in cancer. Citation Format: Hanna Irie, Criseyda Martinez, Yan Xiong, Alison Bartkowski, Jessica Byerly, Jian Jin. A novel PTK6 PROTAC degrader induces apoptosis of drug resistant breast cancer cells [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 PO3-27-02.

Anticancer Activity of Encapsulated Pearl Millet Polyphenol-Rich Extract against Proliferating and Non-Proliferating Breast Cancer Cells In Vitro.

Plant-derived polyphenols are bioactive compounds with potential health-promoting properties including antioxidant, anti-inflammatory, and anticancer activity. However, their beneficial effects and biomedical applications may be limited due to their low bioavailability. In the present study, we have considered a microencapsulation-based drug delivery system to investigate the anticancer effects of polyphenol-rich (apigenin, caffeic acid, and luteolin) fractions, extracted from a cereal crop pearl millet (Pennisetum glaucum), using three phenotypically different cellular models of breast cancer in vitro, namely triple negative HCC1806, ER-positive HCC1428, and HER2-positive AU565 cells. Encapsulated polyphenolic extract induced apoptotic cell death in breast cancer cells with different receptor status, whereas it was ineffective against non-tumorigenic MCF10F cells. Encapsulated polyphenolic extract was also found to be cytotoxic against drug-resistant doxorubicin-induced senescent breast cancer cells that were accompanied by increased levels of apoptotic and necrotic markers, cell cycle inhibitor p21 and proinflammatory cytokine IL8. Furthermore, diverse responses to the stimulation with encapsulated polyphenolic extract in senescent breast cancer cells were observed, as in the encapsulated polyphenolic extract-treated non-proliferating AU565 cells, the autophagic pathway, here cytotoxic autophagy, was also induced, as judged by elevated levels of beclin-1 and LC3b. We show for the first time the anti-breast cancer activity of encapsulated polyphenolic extract of pearl millet and postulate that microencapsulation may be a useful approach for potentiating the anticancer effects of phytochemicals with limited bioavailability.

SiRNA treatment targeting integrin α11 overexpressed via EZH2-driven axis inhibits drug-resistant breast cancer progression

BackgroundBreast cancer, the most prevalent cancer in women worldwide, faces treatment challenges due to drug resistance, posing a serious threat to patient survival. The present study aimed to identify the key molecules that drive drug resistance and aggressiveness in breast cancer cells and validate them as therapeutic targets.MethodsTranscriptome microarray and analysis using PANTHER pathway and StemChecker were performed to identify the most significantly expressed genes in tamoxifen-resistant and adriamycin-resistant MCF-7 breast cancer cells. Clinical relevance of the key genes was determined using Kaplan-Meier survival analyses on The Cancer Genome Atlas dataset of breast cancer patients. Gene overexpression/knockdown, spheroid formation, flow cytometric analysis, chromatin immunoprecipitation, immunocytochemistry, wound healing/transwell migration assays, and cancer stem cell transcription factor activation profiling array were used to elucidate the regulatory mechanism of integrin α11 expression. Tumour-bearing xenograft models were used to demonstrate integrin α11 is a potential therapeutic target.ResultsIntegrin α11 was consistently upregulated in drug-resistant breast cancer cells, and its silencing inhibited cancer stem cells (CSCs) and epithelial-mesenchymal transition (EMT) while restoring sensitivity to anticancer drugs. HIF1α, GLI-1, and EZH2 contributed the most to the regulation of integrin α11 and EZH2 expression, with EZH2 being more necessary for EZH2 autoinduction than HIF1α and GLI-1. Additionally, unlike HIF1α or EZH2, GLI-1 was the sole transcription factor activated by integrin-linked focal adhesion kinase, indicating GLI-1 as a key driver of the EZH2-integrin α11 axis operating for cancer stem cell survival and EMT. Kaplan-Meier survival analysis using The Cancer Genome Atlas (TCGA) dataset also revealed both EZH2 and integrin α11 could be strong prognostic factors of relapse-free and overall survival in breast cancer patients. However, the superior efficacy of integrin α11 siRNA therapy over EZH2 siRNA treatment was demonstrated by enhanced inhibition of tumour growth and prolonged survival in murine models bearing tumours.ConclusionOur findings elucidate that integrin α11 is upregulated by EZH2, forming a positive feedback circuit involving FAK-GLI-1 and contributing to drug resistance, cancer stem cell survival and EMT. Taken together, the results suggest integrin α11 as a promising prognostic marker and a powerful therapeutic target for drug-resistant breast cancer.

Abstract 4673: Genome-scale metabolic models identify gene targets that enhance drug response of drug-resistant breast cancer cells

Abstract Adaptive drug resistance poses a significant therapeutic challenge in treatment of breast cancer patients. Metabolic reprogramming in cancer cells is one of the major mechanisms associated with drug resistance. In this study, we aim to identify gene targets that enhance the drug response of drug-resistant breast cancer cells through downregulation. We hypothesized that metabolic perturbation in drug-resistant breast cancer cells could revert their metabolic features to those of drug-sensitive cells. To predict such gene targets, we used a computational model known as a genome-scale metabolic model (GEM). A GEM simulates the entire metabolic reaction fluxes of a cell under varying genetic and/or environmental conditions. We specifically targeted two engineered MCF7 breast cancer cell lines: one resistant to doxorubicin and the other to paclitaxel. First, we generated proteome data from drug-sensitive and drug-resistant MCF7 cell lines, and used them to construct the cell-specific GEMs. Subsequently, single-gene knockout simulation was conducted using these cell-specific GEMs. The initial list of the gene knockout targets was subjected to pathway analysis involving proteome and metabolome data to finalize the gene targets. The final gene targets were expected to lead to metabolic features similar to those of drug-sensitive MCF7 upon the downregulation. In vitro experiments using inhibitors were conducted to validate these predicted gene targets. This study provides a computational approach that can also be applied to other types of drug-resistant cancer cells. Citation Format: Hae Deok Jung, JinA Lim, Han Suk Ryu, Yoosik Kim, Hyun Uk Kim. Genome-scale metabolic models identify gene targets that enhance drug response of drug-resistant breast cancer cells [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 4673.

Rapid and automatic phenotyping of cells through their annexin-mediated enforced blebbing response

Cellular blebbing has been widely recognized as a hallmark of processes such as apoptosis and cell migration. Here, we developed a novel double-layer compression microfluidic device to trigger the enforced blebbing of cells in a programmable manner. It was found that the critical compression for inducing membrane bleb in highly invasive or drug-resistant breast and lung cancer cell lines could be several times higher than that of their non-invasive or drug-sensitive counterparts. Furthermore, we showed that knockdown of annexin-6, a protein known to be heavily involved in membrane and calcium dynamics in cells, led to a significantly reduced cellular volume, reflecting a lowered intracellular pressure, and an ∼twofold increase in the critical compressive strain for triggering blebbing. The fact that hundreds of cells can be tested and automatically analyzed in our device at the same time highlights the potential of this simple and label-free method in applications such as cell sorting and disease detection.

Co-treatment With Aripiprazole and Vincristine Sensitizes P-Glycoprotein-Overexpressing Drug-resistant MCF-7/ADR Breast Cancer Cells.

Evidence supports that use of aripiprazole sensitizes drug-resistant oral cancer cells. The aim of the study was to investigate whether aripiprazole can achieve sensitization of highly drug-resistant breast cancer cells, as well as identify its relevant mechanisms of action. MCF-7/ADR, KB, and KBV20C breast cancer cells were treated with aripiprazole, vincristine (VIC), vinorelbine, vinblastine and their combination. Cell viability assay, annexin V analyses, cellular morphology and density observation with a microscope, western-blotting, fluorescence-activated cell sorting (FACS), and analysis for P-gp inhibitory activity were performed to investigate the drugs' mechanism of action. We found that high drug resistance in MCF-7/ADR cells results from high P-gp inhibitory activity via overexpression of P-gp. Aripiprazole reduced cell viability, increased G2 arrest, and upregulated apoptosis when used as a co-treatment with VIC. Furthermore, we demonstrated that co-treatment with vinorelbine and vinblastine increased the sensitization of MCF-7/ADR breast cancer cells to aripiprazole. We confirmed that VIC-aripiprazole combination has much higher sensitization effects than either VIC-thioridazine or VIC-trifluoperazine co-treatment in MCF-7/ADR cells, since the previously known bipolar drugs (thioridazine and trifluoperazine) has lower P-gp inhibitory activity. However, aripiprazole-induced sensitization was not observed in VIC-treated MDA-MB-231 breast cancer cells suggesting that combination therapy with aripiprazole is specific for P-gp-overexpressing drug-resistant breast cancer cells. Co-treatment with low doses of aripiprazole sensitized MCF-7/ADR cells to VIC. Combination therapy with aripiprazole may be a valuable tool for delaying or reducing cancer recurrence by targeting P-gp-overexpressing drug-resistant breast cancer cells.

Pitavastatin induces autophagy-dependent ferroptosis in MDA-MB-231 cells via the mevalonate pathway

Triple-negative breast cancer (TNBC) is more prone to recurrence and metastasis relative to other subtypes of breast cancer, leading to an extremely poor prognosis. The increasing potential chemoresistance of TNBC patients is mainly due to that tumor cells escape from apoptosis. In recent years, statins have demonstrated extensive anti-tumor effects. It is worth noting that statins have more effective anti-tumor effects on TNBC cells and drug-resistant breast cancer cells. Therefore, this study examines the superior cytotoxic effects of statins on TNBC cell lines and further explores their potential therapeutic mechanisms. We detected different cell phenotypes and found that statins significantly reduced the cell viability of TNBC cells. Specifically, pitavastatin showed an obvious induction in cell death, cell cycle arrest and oxidative stress in TNBC MDA-MB-231 cells. The reversal effect of iron chelator desferrioxamine (DFO) on the morphological and molecular biological changes induced by pitavastatin has revealed a new mode of cell death induced by pitavastatin: ferroptosis. This ferroptotic effect was strengthened by the decreased expression of glutathione peroxidase 4 (GPx4) as well as newly discovered ferroptosis suppressor protein 1 (FSP1). The data showed that ferroptotic death of MDA-MB-231 cells is autophagy-dependent and mediated by the mevalonate pathway. Finally, we found that therapeutic oral doses of statins can inhibit the growth of transplanted tumors, which establishes statins as a potential treatment for TNBC patients. In conclusion, we found pitavastatin could induce autophagy-dependent ferroptosis in TNBC cells via the mevalonate pathway which may become a potential adjuvant treatment option for TNBC patients.

Critical Aggregation Concentration Can be a Predictor of Doxorubicin Delivery Performance of Self-Assembling Amphiphilic Peptides with Different Hydrophobic Tails

Amphiphilic peptides hold great potential as drug delivery systems. A popular peptide design approach has been to place amino acids in the peptide sequence based on their known properties. On the other hand, the directed discovery approach aims to screen a sequence space for a desired property. However, screening amphiphilic peptides for desirable drug delivery properties is not possible without a quantity that is predictive of these properties. We studied the predictive power of critical aggregation concentration (CAC) values on the drug delivery performance of a series of amphiphilic peptides with different hydrophobic tails and close CAC values. The CAC values were predicted by our previously developed model and doxorubicin was used as a model hydrophobic drug. All peptides showed close drug loading, entrapment efficiency, and release profile. They also formed similar spherical particles by assembling in reverse β-sheet arrangements regardless of drug presence. Moreover, the assembled particles were able to accumulate doxorubicin inside ordinary as well as drug-resistant breast cancer cells and enhance its toxicity up to 39 and 17 folds, respectively. It can be concluded that similar drug delivery properties displayed by the peptides can be attributed to their similar hydrophilic-lipophilic balance as reflected in their close CAC values.

Underlying anti-cancer mechanisms of histone deacetylase (HDAC) inhibitors in tamoxifen-resistant breast cancer cells.

Breast cancer is an important women's malignancy with high cancer-related deaths worldwide. Drug resistance lowers the treatment efficacy in this malignancy. This study aimed to explore the underlying mechanisms of histone deacetylase (HDAC) inhibitor trichostatin A (TSA) to overcome resistance to tamoxifen in breast cancer cells. Tamoxifen-resistance in MCF-7 breast cancer cells was simulated. MTT assay was used to detect the cytotoxic effects of HDAC inhibitor and PI3K inhibitor on the cancer cells. Trans-well assay was applied to evaluate the invasion and migration of the treated cancer cells. Flow cytometer assay was also applied to evaluate cell cycle phases in the treated cancer cells. Finally, expression of vascular endothelial growth factor (VEGF), E-cadherin, Vimentin, phosphorylated phosphatidylinositol kinase (p-PI3k), phosphorylated protein kinase B (p-AKT), and phosphorylated mammalian target protein of rapamycin (p-mTOR) was evaluated by western blotting. The obtained results indicated that HDAC inhibitor treatments significantly decreased viability, migration, and invasion in the cancer cells. Furthermore, the frequency of the treated cancer cells significantly increased in the S phase as well as significantly decreasing in the G2/M phase of the cell cycle. Moreover, HDAC inhibitor modified levels of VEGF, E-cadherin, Vimentin, p-PI3k, p-AKT, and p-mTOR proteins. However, HDAC inhibitor combined with PI3K inhibitor exerts more profound effects on the cancer cells as compared to HDAC inhibitor monotherapy. HDAC inhibitors inhibited the survival of breast cancer drug-resistant cells, invasion, migration, and angiogenesis by inhibiting the PI3k/Akt/mTOR signaling pathway.

Effect of miR-200b Liposome Nanoparticles on Chemotherapy Resistance in Rats with Breast Cancer Through Induction of Epidermal Growth Factor Receptor/Extracellular Signal-Regulated Kinase Signal Pathway

This study assessed the effect of miR-200b liposome nanoparticles in restraining chemotherapy resistance in rats with breast cancer through induction of epidermal growth factor receptor enzyme-linked immunosorbent assay enzyme-linked immunosorbent assay (EGFR)/extracellular regulated protein kinases (ERK) signal pathway. 50 rats were divided into 4 sets, which included control set, empty carrier set, miR-200b set, and set of miR-200b packaged with liposome nanoparticles. The liposome nanoparticles were prepared and identified, and drug-resistant breast cancer cells were observed and identified. The growth inhibition ratio, miR-200b expression, drug-resistance, growth curve, drug resistance of cells, EGFR and ERK protein expressions were observed. miR-200b expression in the et of miR-200b packaged with liposome nanoparticles was highest, second in the miR-200b set and empty carrier set, and lowest in the control set. The IC50 value in the miR-200b packaged with liposome nanoparticles was highest. The absorbance in the set of miR-200b liposome nanoparticles was lowest. The immunofluorescence (IF) strength of miR-200b in the miR-200b liposome nanoparticles was highest. The EGFR and ERK protein expressions, and levels of pEGFR and p-ERK in the miR-200b liposome nanoparticles set was highest. In conclusion, chemotherapy resistance of breast cancer cells could be restrained by miR-200b liposome nanoparticles through restraining of the EGFR/ERK signal pathway.

THU546 A Lasofoxifene/Elacestrant Hybrid Antiestrogen Shows Effective Anti-tumoral Activities In Y537S ESR1 Breast Cancer Xenografts

Abstract Disclosure: K.S. Young: None. G.R. Hancock: None. S. Kregel: None. S.W. Fanning: Advisory Board Member; Self; Olema Oncology. Grant Recipient; Self; Olema Oncology. In the United States, breast cancer is the second leading cause of cancer related deaths among women. Over 70 percent of these breast cancer cases are classified as overexpressing Estrogen Receptor alpha (ERα), denoting that the hormone estrogen fuels the cancer growth. In ER+ breast cancer patients, a distinct tyrosine to serine missense mutation at position 537 (Y537S) leads to hormone- independent ERα activity, causing drug resistance and increased metastatic potential. By favoring the active conformation of ERα, the Y537S mutation reduces binding affinity of small molecule drugs by 5-10 fold. Additionally, this mutation adversely effects the allosteric rearrangement of the receptor that is needed to achieve therapeutic efficacy. Recently, we identified a common structural interaction that distinguishes effective versus ineffective therapeutic antagonists in Y537S breast cancer cells. Based on this relationship, we have developed a new isoquinoline- based antiestrogen (T6I-29-1A) to aid in interpretation of the relationship between ligand binding pose and antagonistic efficacy. Our data suggest that this novel pose effectively antagonizes mutant ERα in breast cancer cells by significantly blunting cell proliferation and downregulating transcriptional activity. Importantly, T6I-29-1A shows potent anti-tumoral activity in ectopic murine xenografts of Y537S ESR1 MCF7 cells, is orally available, and shows a favorable DMPK and ADME profile. Additionally, mice treated with T6I-29-1A exhibited decreased distant metastases compared to hormone-only control. Collectively, these studies point to a distinct relationship between ERα ligand binding pose and novel anti-metastatic activities in drug resistant Y537S ESR1 breast cancer cells. Presentation: Thursday, June 15, 2023

Biomimetic on-chip assay reveals the anti-metastatic potential of a novel thienopyrimidine compound in triple-negative breast cancer cell lines.

Introduction: This study presents a microfluidic tumor microenvironment (TME) model for evaluating the anti-metastatic efficacy of a novel thienopyrimidines analog with anti-cancer properties utilizing an existing commercial platform. The microfluidic device consists of a tissue compartment flanked by vascular channels, allowing for the co-culture of multiple cell types and providing a wide range of culturing conditions in one device. Methods: Human metastatic, drug-resistant triple-negative breast cancer (TNBC) cells (SUM159PTX) and primary human umbilical vein endothelial cells (HUVEC) were used to model the TME. A dynamic perfusion scheme was employed to facilitate EC physiological function and lumen formation. Results: The measured permeability of the EC barrier was comparable to observed microvessels permeability in vivo. The TNBC cells formed a 3D tumor, and co-culture with HUVEC negatively impacted EC barrier integrity. The microfluidic TME was then used to model the intravenous route of drug delivery. Paclitaxel (PTX) and a novel non-apoptotic agent TPH104c were introduced via the vascular channels and successfully reached the TNBC tumor, resulting in both time and concentration-dependent tumor growth inhibition. PTX treatment significantly reduced EC barrier integrity, highlighting the adverse effects of PTX on vascular ECs. TPH104c preserved EC barrier integrity and prevented TNBC intravasation. Discussion: In conclusion, this study demonstrates the potential of microfluidics for studying complex biological processes in a controlled environment and evaluating the efficacy and toxicity of chemotherapeutic agents in more physiologically relevant conditions. This model can be a valuable tool for screening potential anticancer drugs and developing personalized cancer treatment strategies.

New copper(II) complex based-thiosemicarbazone and phenanthroline: DNA/BSA binding, antiproliferative activity, DFT and docking studies

A new copper(II) complex {Cu(HPP)}, bromo(1,10-phenanthroline)(triphenylphosphine)copper(I) with 2-hydroxy-5-methoxyacetophenone thiosemicarbazone (HMAT) was synthesized and characterized by experimental FT-IR, Raman, UV–vis, TGA and EPR spectral analysis. The Cu(HPP) was theoretically modeled using the B3LYP/VTZ method/basis set and the values of the spectroscopic parameters were calculated by the DFT method. The coordination geometry around the Cu(II) in the compound was predicted as an elongated octahedral. Spectroscopic investigations showed the intercalative binding mechanism of the Cu(HPP) with calf-thymus deoxyribonucleic acid (ct-DNA). Spectroscopic techniques were also used to evaluate the interaction of the Cu(HPP) with bovine serum albumin (BSA), which revealed that the Cu(HPP) could bind to BSA significantly. In addition, the molecular docking between the Cu(HPP) and BSA was investigated to support the bonding mechanism. Further, we studied the anticancer activity of the Cu(HPP) in drug resistant breast cancer cell line (MDA-MB-231), with a focus on the proliferative characteristics. Our findings emphasize that this newly synthetized complex has a significant cytotoxic effect on the cells and can be utilized as a candidate chemotherapeutic agent to effectively target breast cancer.

Metabolomics Analysis Reveals Altered Metabolic Pathways and Response to Doxorubicin in Drug-Resistant Triple-Negative Breast Cancer Cells.

This study aimed to investigate metabolic changes following the acquisition of resistance to doxorubicin in the triple-negative breast cancer (TNBC) cell line MDA-MB-231. Two drug-resistant cell lines, DOX-RES-50 and DOX-RES-100, were generated by treating MDA-MB-231 cells with doxorubicin for 24 h and allowing them to recover for six weeks. Both drug-resistant cell lines demonstrated an increase in doxorubicin IC50 values, indicating acquired drug resistance. Metabolomics analysis showed clear separation between the parental MDA-MB-231 cell line and the drug-resistant cell lines. Pathway analysis revealed that arginine and proline metabolism, glutathione metabolism, and beta-alanine metabolism were significantly perturbed in the drug-resistant cell lines compared to the parental cell line. After matching signals to an in-house library of reference standards, significant decreases in short- and medium-chain acylcarnitines and significant increases in long-chain acylcarnitines, 5-oxoproline, and 7-ketodeoxycholic acid were observed in the resistant cell lines as compared to the parental MDA-MB-231 cell line. In addition to baseline metabolic differences, we also investigated differences in metabolic responses in resistant cell lines upon a second exposure at multiple concentrations. Results indicate that whereas the parental MDA-MB-231 cell line had many metabolites that responded to doxorubicin in a dose-dependent manner, the two resistant cell lines lost a dose-dependent response for the majority of these metabolites. The study's findings provide insight into how metabolism is altered during the acquisition of resistance in TNBC cells and how the metabolic response to doxorubicin changes upon repeated treatment. This information can potentially identify novel targets to prevent or reverse multi-drug resistance in TNBC, and also demonstrate the usefulness of metabolomics technology in identifying new mechanisms of drug resistance in cancer and potential drug targets.

The Role of ARHGAP1 in Rho GTPase Inactivation during Metastasizing of Breast Cancer Cell Line MCF-7 after Treatment with Doxorubicin.

Breast cancer is the most prevalent cancer type in women worldwide. It proliferates rapidly and can metastasize into farther tissues at any stage due to the gradual invasiveness and motility of the tumor cells. These crucial properties are the outcome of the weakened intercellular adhesion, regulated by small guanosine triphosphatases (GTPases), which hydrolyze to the guanosine diphosphate (GDP)-bound conformation. We investigated the inactivating effect of ARHGAP1 on Rho GTPases involved signaling pathways after treatment with a high dose of doxorubicin. Label-free quantitative proteomic analysis of the proteome isolated from the MCF-7 breast cancer cell line, treated with 1 μM of doxorubicin, identified RAC1, CDC42, and RHOA GTPases that were inactivated by the ARHGAP1 protein. Upregulation of the GTPases involved in the transforming growth factor-beta (TGF-beta) signaling pathway initiated epithelial-mesenchymal transitions. These findings demonstrate a key role of the ARHGAP1 protein in the disruption of the cell adhesion and simultaneously allow for a better understanding of the molecular mechanism of the reduced cell adhesion leading to the subsequent metastasis. The conclusions of this study corroborate the hypothesis that chemotherapy with doxorubicin may increase the risk of metastases in drug-resistant breast cancer cells.

MicroRNA functional metal-organic framework nanocomposite for efficient inhibition of drug-resistant breast cancer cells

MicroRNA functional metal-organic framework nanocomposite for efficient inhibition of drug-resistant breast cancer cells