MDA-MB231 Breast Cancer Cell Lines Research Articles

Abstract PO1-13-08: Comparative analysis of stearoyl-CoA desaturase 1 expression and activity index in model cell lines of breast cancer subclasses

Abstract Introduction Due to the unique conditions of the tumor microenvironment, such as hypoxia, poor angiogenesis, and mitochondrial dysfunction, cancer cells face challenges in obtaining nutrients and energy supply. However, monounsaturated fatty acids have been identified as preferred substrates for energy generation and maintenance of cellular structures in cancer cells. These fatty acids can be obtained through de novo fatty acid synthesis. Stearoyl-CoA desaturase 1 (SCD1) is the primary enzyme involved in the biosynthesis of monounsaturated fatty acids from saturated fatty acids and is known to be upregulated in various malignancies, including breast cancer. This study aimed to assess the expression and activity index of SCD1 in well-characterized MCF-7, SK-BR3, and MDA-MB231 breast cancer cell lines, representing luminal A/B, HER2-enriched, and triple-negative subtypes, respectively. Methods The breast cancer cell lines were cultured in RPMI-1640 medium with 10% fetal bovine serum at 37°C, 5% CO2, and 95% humidity for 72 hours. After harvesting the cells, SCD1 expression was analyzed using real-time quantitative PCR, and the activity index was determined by measuring the ratio of monounsaturated fatty acids to saturated fatty acids using capillary gas-liquid chromatography. Results MCF-7 cell line showed a significantly higher SCD1 expression compared to MDA-MB231 (250-fold, p< 0.0001) and SK-BR3 (83-fold, p< 0.0001) cell lines. The activity index of SCD1 was significantly higher in both MCF-7 and MDA-MB231 cell lines with fold changes of 2.6 and 2.5, respectively, compared to SK-BR3 cell line (p=0.004 for both). Conclusion Cell model assays demonstrated that the luminal A/B and triple-negative subtypes showed a higher capacity to convert saturated fatty acids to monounsaturated fatty acids through SCD1 enzyme activity, indicating a different lipid metabolism profile in the HER2-enriched subtype. These new findings reveal differences in SCD1 expression and activity among breast cancer subclasses. They highlight vulnerabilities in metabolism and identify potential therapeutic targets with clinical implications for managing breast cancer. Citation Format: Hamid-Reza Feizi, Amir Mehdizadeh, Zohreh Sanaat, Khadijeh Abbasi, Frank Gieseler, Masoud Darabi. Comparative analysis of stearoyl-CoA desaturase 1 expression and activity index in model cell lines of breast cancer subclasses [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 PO1-13-08.

Synthesis and anti-breast cancer evaluation of fused imidazole-imidazo[1,2-c][1,2,3]triazoles: PEG-400 mediated one-pot reaction under ultrasonic irradiation

Synthetic chemists have organized easy and effective ways for perfect synthesis in response to the requirement for scaffolds that are crucial for medical applications. To investigate the synthesis of fused 1,2,3-triazoles in the presence of ultrasound, the [3 + 2] cycloaddition followed by CN bond formation reaction between 2-chloro-N-(1-methyl-1H-imidazol-2-yl)acetamide and substituted aryl iodoalkynes was carried out ourpreviously reported condition. The cancer activity of the synthesized compounds were then tested in vitro against two breast cancer cell lines MCF-7 and MDA-MB231 and some of the compounds 5g and 5j showed more potent activity against MCF-7 compared to standard erlotinib (IC50 = 4.70 ± 0.11 μM) with IC50 values 4.02 ± 0.74 and 4.23 ± 0.65 μM. Later, in vitro EGFR results revealed that compound 5g (IC50 = 0.38 ± 0.02 μM) have shown more effective than the conventional medicine erlotinib (IC50 = 0.42 ± 0.04 μM). Compounds 5j (IC50 = 0.42 ± 0.05 μM) have shown equipotent, 5i (IC50 = 0.53 ± 0.02 μM) and 5k (IC50 = 0.58 ± 0.02 μM) were shown good activity compared to the standard erlotinib. In silico investigations of more potent compounds (5g, 5i, 5j, 5k, and 5q) and erlotinib on the EGFR protein indicated that all five compounds had comparable binding energies and inhibition constants than the erlotinib.

In vitro ANTI-CANCER EFFECTS OF QUERCETIN ON TRIPLE NEGATIVE BREAST CANCER CELL LINE

Phytochemicals are widely being explored for their cancer preventive properties in today’s oncotherapy. Quercetin is a major constituent of various dietary products and its anti-cancer potential was explored on different cancer cell lines. The present study was conducted to find out the anti-proliferative effects of quercetin on human triple negative breast cancer cell line MDA-MB The anti-cancer potential of quercetin, nano-quercetin and doxorubicin at various concentrations were assessed by cellular cytotoxicity (MTT) assay. The IC50 values of quercetin, nano-quercetin and doxorubicin on MDA-MB 231 cell line were 394.8, 204.6 and 17.17 μM, respectively. In vitro anti-cancer effects of these drugs were manifested as apoptosis and cellular toxicity. The cytotoxicity was moderate in quercetin, remarkable in nano-quercetin and strong in doxorubicin treatments. The in vitro anti-cancer effect of quercetin was comparable with the standard drug doxorubicin. Considering the potential side effects of doxorubicin, the quercetin might be explored with further studies in the treatment of mammary tumours in animals and humans.

Synthesis of Self Permeable Antisense PMO Using C5-Guanidino-Functionalized Pyrimidines at the 5'-End Enables Sox2 Downregulation in Triple Negative Breast Cancer Cells.

Delivery of macromolecular drugs inside cells has been a huge challenge in the field of oligonucleotide therapeutics for the past few decades. Earliest natural inspirations included the arginine rich stretch of cell permeable HIV-TAT peptide, which led to the design of several molecular transporters with varying numbers of rigid or flexible guanidinium units with different tethering groups. These transporters have been shown to efficiently deliver phosphorodiamidate morpholino oligonucleotides, which have a neutral backbone and cannot form lipoplexes. In this report, PMO based delivery agents having 3 or 4 guanidinium groups at the C5 position of the nucleobases of cytosine and uracil have been explored, which can be assimilated within the desired stretch of the antisense oligonucleotide. Guanidinium units have been connected by varying the flexibility with either a saturated (propyl) or an unsaturated (propargyl) spacer, which showed different serum dependency along with varied cytoplasmic distribution. The effect of cholesterol conjugation in the delivery agent as well as at the 5'-end of full length PMO in cellular delivery has also been studied. Finally, the efficacy of the delivery has been studied by the PMO mediated downregulation of the stemness marker Sox2 in the triple-negative breast cancer cell line MDA-MB 231. These results have validated the use of this class of delivery agents, which permit at a stretch PMO synthesis where the modified bases can also participate in Watson-Crick-Franklin base pairing for enhanced mRNA binding and protein downregulation and could solve the delivery problem of PMO.

Synthesis of triazole bridged N-glycosides of pyrazolo[1,5-a]pyrimidinones as anticancer agents and their in silico docking studies.

In the pursuit of novel therapeutic agents, we present a comprehensive study on the design, synthesis, and evaluation of a diverse library of triazole bridged N-glycosides of pyrazolo[1,5-a]pyrimidinones, employing a microwave-assisted synthetic approach via 'click chemistry'. This methodology offers efficient and accelerated access to the glycohybrids, showcasing improved reaction conditions that yield high-quality products. In this research endeavor, we have successfully synthesized a series of twenty-seven triazole bridged N-glycosides of pyrazolo[1,5-a]pyrimidinones. Our investigation extends beyond synthetic endeavors to explore the potential therapeutic relevance of these compounds. We subjected them to rigorous in vitro screening against prominent breast cancer cell lines MCF-7, MDA-MB231, and MDA-MB453. Among the library of compounds synthesized, (2S,3S,4R,5S,6S)-2-(acetoxymethyl)-6-(4-((5-(4-methoxyphenyl)-7-oxopyrazolo[1,5-a]pyrimidin-1(7H)-yl)methyl)-1H-1,2,3-triazol-1-yl)tetrahydro-2H-pyran-3,4,5-triyl triacetate emerged as a potent compound, exhibiting remarkable anti-cancer activity with an IC50 value of 27.66 μM against the MDA-MB231 cell line. Additionally, (2S,3R,4R,5S,6S)-2-(acetoxymethyl)-6-(4-((7-oxo-5-(4-(trifluoromethyl)phenyl)pyrazolo[1,5-a]pyrimidin-1(7H)-yl)methyl)-1H-1,2,3-triazol-1-yl)tetrahydro-2H-pyran-3,4,5-triyl triacetate displayed notable inhibitory potential against the MCF-7 cell line, with an IC50 value of 4.93 μM. Furthermore, in silico docking analysis was performed to validate our experimental findings. These findings underscore the promise of our triazole bridged N-glycosides of pyrazolo[1,5-a]pyrimidinones as potential anti-cancer agents. This research not only enriches the field of glycohybrid synthesis but also contributes valuable insights into the development of novel anti-cancer therapeutics.

Preliminary anticancer evaluation of new Pd(II) complexes bearing NNO donor ligands

In this study we presented a novel series of NNO tridentate ligands generating imino, amido and oxo donor pocket for Pd(II) coordination. All the compounds were meticulously characterized by elemental analysis and advanced spectroscopic techniques, including FTIR, proton and carbon NMR. The synthesized compounds underwent rigorous evaluation for their potential as anti-cancer agents, utilizing the aggressive breast cancer cell lines MDA-MB (ATCC) and MCF-7 as a crucial model for assessing growth inhibition in cancer cells. Remarkably, the MTT assay unveiled the robust anti-cancer activity for all palladium complexes against MDA-MB-231 and MCF-7 cells. Particularly, complex [Pd(L1)(CH3CN)] exhibited exceptional potency with an IC50 value of 25.50 ± 0.30 µM (MDA-MB-231) and 20.76 ± 0.30 µM (MCF-7), compared to respective 27.00 ± 0.80 µM and 24.10 ± 0.80 µM for cisplatin, underscoring its promising therapeutic potential. Furthermore, to elucidate the mechanistic basis for the anti-cancer effects, molecular docking studies on tyrosine kinases, an integral target in cancer research, were carried out. The outcome of these investigations further substantiated the remarkable anticancer properties inherent to these innovative compounds. This research offers a compelling perspective on the development of potent anti-cancer agents rooted in the synergy between ligands and Pd(II) complexes and presenting a promising avenue for future cancer therapy endeavors.

A pilot study: Changes of MDAMB-231 cancer cell line response to synthesized oleic acid – coated MgFe2O4 nano ferrite compound and its cytotoxic effects on L929 cell line

In this investigation, we synthesized MgFe2O4 nano ferrite compounds using the sol-gel method and coated them with oleic acid. The synthesized compounds were evaluated for cytotoxicity study on the L929 cell line and the anticancer activity against the breastcancer-MDAMB-231 cellline using in vitro approach. The physical structure of the compounds was confirmed to have a cubic spinel structure and Fd3m space group using X-ray diffraction (XRD). Scherrer's formula revealed crystallite sizes of 11 nm for MgFe2O4and 33 nm for oleic acid-coated MgFe2O4 nanoferrites. Fourier transform infrared (FTIR) spectroscopy confirmed the existence of MgFe2O4 inuncoated and coated compounds. Scanning electron microscopy (SEM) was used to examine the surface structure and morphology of the synthesized compounds. The compounds show a grain-like structure with a little agglomeration. With the help of histogram graph average size of the particles are determined, where the MgFe2O4 and coated MgFe2O4 have 17.2 and 20 nm average particle sizes. Testing of magnetic properties was done with a vibrating sample magnetometer (VSM), demonstrating ferromagnetic properties for the samples. Cytotoxicity tests revealed that MgFe2O4 exhibited higher cytotoxicity compared to oleic acid-coated MgFe2O4 nanoferrite on L929 cells. MgFe2O4 & oleic acid-coated MgFe2O4 compounds were tested on the MDAMB-231 breast cancer cell line, with the uncoated sample displaying significantly greater anticancer activity, as evidenced by a higher percentage of cell viability and a lower IC50 value of 55.67 µg compared to 65.97 µg for the coated sample.

In Vitro Cytotoxicity Efficiency of Extracellular L-Glutaminase Produce by Mesophilic Bacteria, Kurthia Gibsonii on Lncap, MDA-MB 231 and Hepg-2 Cell Lines

Mesophilic bacteria from soil habitat have been reported to produce extracellular L-glutaminase. The present study was carried out to anticancer screening of L-glutamiase producing bacteria (Kurthia gibsonii) from soil sample of cattle feeding site from Satara parisar, Chhatrapati Sambhajinagar. Results showed, among three soil samples of cattle feeding farms, Kurthia gibsonii was isolated. From that exhibited the highest L-glutaminase activity. Moreover, the in vitro cytotoxic activity of L-glutaminase against the (Lymph Node Carcinoma of the Prostate) LNCaP, (an epithelial, human breast cancer cell line) MDA-MB 231 and hepatocellular (HepG-2) carcinoma cell lines at different concentration (0.47, 0.94, 1.88, 3.75, 7.50, 15.00, 30.00 and 60.00 μg/ml) by the MTT assay and compared with the standard Doxrubcin. The antitumor effect against human liver carcinoma cell line revealed that L-glutaminase produced by Kurthia gibsonii showed potent cytotoxic activity of tested cell line in a dose-dependent manner with an LC50 value of 4.1 μg/ml.

Quercetin-loaded solid lipid nanoparticles exhibit antitumor activity and suppress the proliferation of triple-negative MDA-MB 231 breast cancer cells: implications for invasive breast cancer treatment.

Quercetin (QC) is a naturally occurring flavonoid found in abundance in fruits and vegetables. Its anti-cancer and anti-inflammatory properties have been previously demonstrated, but its low bioavailability hampers its clinical use. Triple-negative breast cancer is a subtype of breast cancer with a poor response to chemotherapy. This study investigates the anti-cancer effects of quercetin-solid lipid nanoparticles (QC-SLN) on the triple-negative breast cancer cell line MDA-MB231. MCF-7 and MDA-MB231 cells were treated with 18.9 µM of QC and QC-SLN for 48h. Cell viability, apoptosis, colony formation assay, and the anti-angiogenic effects of the treatment were evaluated. QC-SLN displayed optimal properties (particle size of 154nm, zeta potential of -27.7 mV, encapsulation efficiency of 99.6%, and drug loading of 1.81%) and exhibited sustained release of QC over 72h. Compared to the QC group, the QC-SLN group showed a significant decrease in cell viability, colony formation, angiogenesis, and a substantial increase in apoptosis through the modulation of Bax and Bcl-2 at both gene and protein levels. The augmentation in the proportion of cleaved-to-pro caspases 3 and 9, as well as poly (ADP-ribose) polymerase (PARP), under the influence of QC-SLN, was conspicuously observed in both cancer cell lines. This study showcases quercetin-solid lipid nanoparticles (QC-SLN) as a promising therapy for triple-negative breast cancer. The optimized QC-SLN formulation improved physicochemical properties and sustained quercetin release, resulting in reduced cell viability, colony formation, angiogenesis, and increased apoptosis in the MDA-MB231 cell line. These effects were driven by modulating Bax and Bcl-2 expression, activating caspases 3 and 9, and poly (ADP-ribose) polymerase (PARP). Further in vivo studies are needed to confirm QC-SLN's efficacy and safety.

Does broccoli (brassica oleracea var. italica) extract have a potential therapeutic targets on human breast cancer (MDA-MB-231) using AgNOR detection method?

In this study, it was aimed to determine the in vitro effect of the extract obtained from mature broccoli on the breast cancer cell line. MDA-MB231 breast cancer cell line was used in the study. MDA-MB-231 cells were exposed to broccoli extract at 37°C and 5% CO2 for varying durations (24 and 48 hours) and doses (125 and 250 µl/ml).At the end of the incubation period, viability, apoptosis, cell cycle and AgNOR protein status of MDA-MB-231 cells were examined in the Muse Cell Analyzer. In the groups containing broccoli extract, a decrease in the percentage of viable cells and a significant increase in the percentage of early and total apoptosis were observed for both doses compared to the control. In the cell cycle test, the number of cells in the S phase increased in all groups.It was observed that the groups containing broccoli extract slowed down the cell cycle in the transition to the S checkpoint. AgNOR staining results also supported cell cycle and apopitosis, and AgNOR number and TAA/NA ratio decreased in the 125 µl/ml broccoli extract group after 24-48 hours and were found to be statistically significant compared to the control group. It was determined that broccoli increased apoptosis on breast cancer cells by various mechanisms and inhibited cell viability/cell growth. The results were similar to the results of AgNOR protein synthesis. The study showed that the regular and correct consumption of broccoli could be effective in preventing cancer formation and slowing its progression.

In Vitro Evaluation of Biological and Anticancer Activities Exhibited by Five Varieties of Vitis vinifera L.

Vitis vinifera commonly known as grapevine is one of the most important fruit crops worldwide. Its cultivation started more than 7000 years ago in the Near East, and over the millennia was followed by the development of thousands of cultivars that were further selected and characterized for specific purposes. Its important pharmacological value and its richness in phytoconstituents were the triggers to perform this project. Seven extracts were prepared from five different V. vinifera varieties (V. vinifera 'Black Pearl' (BP), V. vinifera 'Red Glob' (RG), V. vinifera 'Crimson' (CR), V. vinifera 'Beitamouni' (BE) and V. vinifera 'Superior' (SU)) by separating the pulp from the seeds, followed by methanolic extraction. The phytochemical analysis showed that red colored grapes (RE, BP and CR), the seeds from V. vinifera 'Black Pearl' and V. vinifera 'Red Globe' contain higher amounts of primary and secondary metabolites such as polyphenols, anthocyanins and reducing sugars. In addition to their richness in phytoconstituents, these varieties/seeds possess an important antioxidant activity. The results of the cell viability assays showed that the red varieties have a potential anticancer activity against Capan-2 pancreatic cancer and MDA-MB231(TNBC) breast cancer cell lines, with the greatest promise when combined with the seeds.

Fractions of Methanol Extracts from the Resurrection Plant Haberlea rhodopensis Have Anti-Breast Cancer Effects in Model Cell Systems

Breast cancer is among the most problematic diseases and a leading cause of death in women. The methods of therapy widely used, so far, are often with many side effects, seriously hampering patients’ quality of life. To overcome these constraints, new cancer treatment alternatives are constantly tested, including bioactive compounds of plant origin. Our aim was to study the effects of Haberlea rhodopensis methanol extract fractions on cell viability and proliferation of two model breast cancer cell lines with different characteristics. In addition to the strong reduction in cell viability, two of the fractions showed significant influence on the proliferation rate of the hormone receptor expressing MCF7 and the triple negative MDA-MB231 breast cancer cell lines. No significant effects on the benign MCF10A cell line were observed. We applied a large scale non-targeted approach to purify and identify highly abundant compounds from the active fractions of H. rhodopensis extracts. By the combined NMR/MS approach, myconoside was identified in the fractions and hispidulin 8-C-(6-O-acetyl-2″-O-syringoyl-β-glucopyranoside) was found in one of them. We further performed molecular docking analysis of possible myconoside interactions with several proteins, important for breast cancer proliferation. High probability of binding was established for GLUT1 transporter, estrogen receptor and MYST acetyltransferase. Our results are a good background for future studies on the use of myconoside for targeted breast cancer therapy.

Insights into the therapeutic outcomes of trimetazidine/doxorubicin combination in Ehrlich solid-phase carcinoma mouse tumor model

One of the key features of cancer is metabolic reprogramming that can be exploited to sensitize cancer cells to chemotherapy. Trimetazidine (TMZ) is a metabolic anti-ischemic drug that blocks the activity of long-chain 3-ketoacyl CoA thiolase leading to the inhibition of fatty acid oxidation. AimsThe objective of the current investigation was to evaluate the idea that TMZ could synergize the antitumor activity of doxorubicin (DOX). Main methodsThe hypothesis was examined in vitro using the human breast cancer cell lines MCF-7 and MDA-MB231. In addition, the in vivo experiments were conducted using the Ehrlich solid phase carcinoma model. Key findingsIn vitro cytotoxicity experiments demonstrated that TMZ improved the potency of DOX in MCF-7 cell lines in a synergistic manner. In vivo testing confirmed that DOX/TMZ combination exhibits synergistic effect at both DOX/TMZ 1:10 and 1:5 ratios, where DOX was administered at one tenth and one fifth of its original dose, respectively. The co-treatment (1:5 ratio) significantly reduced tumor Nicotinamide adenine dinucleotide (NAD)+/NADH ratio (6.1-fold) and Adenosine triphosphate (ATP) levels (61 %) with concurrent activation of AMP-activated protein kinase (AMPK) (2.2-fold) and peroxisome proliferator-activated receptor-gamma coactivator (PGC)1-α (5.5-fold) protein expression versus control. The same treatment decreased the nuclear levels of NF-κB (p65) (57.5 %) and induced tumor apoptosis as evidenced by elevated Bax/Bcl-2 ratio (6.8-fold) along with active caspase-3 levels (6.6-fold) against control. SignificanceThe current investigation constitutes a proof-of-concept study that provided preclinical evidence for the anticancer activity of DOX/TMZ combination and warrants further investigation for repurposing TMZ in DOX protocols.

Abstract 6089: Identification of novel YAP/TAZ pathway regulators in the triple-negative breast cancer cell line MDA-MB231 using single-cell CRISPR screening

Abstract The Hippo signaling cascade is a major pathway that integrates a broad spectrum of mechanosensory signals at the plasma membrane and regulates response via control of cell proliferation, self-renewal, differentiation, and apoptosis. Dysregulation of this pathway has been observed across a range of cancer types and results in an altered activity of its primary downstream effectors, the oncogenic transcription factors YAP/TAZ. For example, both germline and somatic loss-of-function mutations in the tumor suppressor gene NF2, a component of Hippo, induce hyperactivation of YAP/TAZ, transcriptional changes and ultimately result in tumor growth. The Hippo signaling pathway is an attractive target for drug discovery efforts, however, it is highly complex and still incompletely understood. Hence it is indispensable to get a deeper insight into the Hippo - YAP/TAZ signaling axis. To this end, we performed a genome-wide CRISPR knockout screen in the triple-negative breast cancer (TNBC) cell line MDA-MB231 (NF2LOF) expressing a YAP/TAZ reporter construct. We identified both negative and positive regulators of YAP/TAZ in breast cancer cells. In a second step, screening hits were further characterized in a focused single-cell CRISPR screen (Perturb-Seq), aiming at better understanding of the effects on YAP/TAZ activity regulation and downstream effects on gene expression. Here we present the technical details of our screening approaches and the results of perturbing known and novel regulators of YAP/TAZ on single cell level. We discuss the use of Perturb-Seq in the initial validation of hits from genome-wide screens and provide data that may serve as a basis for future drug discovery efforts, seeking for novel and effective treatments for triple-negative breast cancers and other malignancies with Hippo pathway alterations. Citation Format: Mareike Berlak, Zuzanna Makowska, Filippos Klironomos, Julia Kuehnlenz, Atanas Kamburov, Andreas Steffen, Martin Lange, Barbara Nicke, Ralf Lesche, Peter Staller, Charlotte Kopitz, Jan Naujoks. Identification of novel YAP/TAZ pathway regulators in the triple-negative breast cancer cell line MDA-MB231 using single-cell CRISPR screening [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6089.

The synergistic effect of chimeras consisting of N-terminal smac and modified KLA peptides in inducing apoptosis in breast cancer cell lines

Drug resistance is one of the most important obstacles in effective cancer therapy triggered through various mechanisms. One of these mechanisms is caused by the upregulation of Inhibitor of Apoptosis Proteins (IAPs). IAPs, inhibit apoptosis through direct and/or indirect caspase inhibition, which themselves are antagonized by an endogenous protein called Second Mitochondrial-derived Activator of Caspases, Smac/Diablo, mediated by the presence of a tetrapeptide IAP binding motif at its N-terminus. Accordingly, Smac-based peptides are under intense investigation as anti-cancer drugs and have reached Phase 2 clinical trials, although, Smac based peptides or mimetics alone have not been effective as anti-cancer agents. On the other hand, KLA peptide has shown major toxicity against cancer cells through the induction of apoptosis. Consequently, we designed an anti-cancer chimera by fusing an octa-peptide from the N-terminus of mature Smac protein to a modified proapoptotic KLA peptide (KLAKLCKKLAKLCK) to be called Smac-KLA. This chimera, therefore, possesses both proapoptotic and anti-IAP activities. In addition, we dimerized this chimera via intermolecular disulfide bonds in order to enhance their cellular permeability. Both the Smac-KLA monomeric and dimeric peptides exhibited cytotoxic activity against both MCF-7 and MDA-MB231 breast cancer cell lines at low micromolar concentrations. Importantly, the dimerization of the chimeras enhanced their potency 2-4- fold due to higher cellular uptake.

Abstract P6-14-16: Claudin-9 and its subcoat anchorage proteins ZO-1 and ZO-3 in breast cancer, the clinical and therapeutic significance

Abstract Introduction. Claudin-9 (CLDN9), a member of the claudin protein family, is thought to play a role in the control of tight junctions (TJ) in various cell types. CLDN9 protein needs intracellular subcoat proteins, primarily the Zonula Occluden (ZO)-1 and ZO-3 to anchor to the cytoskeleton in order to form TJ with other proteins, including occludin. In the body, CLDN9 is highly expressed in endocrine tissues but is relatively low in mammary tissues. The role of CLDN9 is not well understood in cancer. In the present study, we have for the first time examined the pattern of CLDN9 expression at protein and transcript levels in breast cancer and explored its clinical and therapeutic implications. Methods. CLDN9 protein and CLDN9 transcript in fresh frozen human mammary tissues were evaluated by immunohistochemistry and quantitative transcript analyses and, together with the ZO family members and occludin in our database, correlated with clinical indicators. Assessment of expression in a range of cell lines was also determined. The levels of CLDN9 transcript, was also assessed against the therapeutic responses of the patients to chemotherapies by using a dataset from TCGA database. Results. Breast tumour tissues had high levels of CLDN9 transcript in tumours versus normal tissues. However, high grade breast tumours had significantly lower levels than low grade (p=0.02 and p=0.003, grade-2 and 3 vs grade-1 respectively). Patients with metastasis also had significantly lower levels than those without (p=0.0075). Patients who died of breast cancer had higher levels of the transcript than those who survived, although this was not significant. CLDN9 expression was significantly correlated with ZO-1 (r=0.20, p< 0.001) and ZO-3 (r=0.179, p< 0.01), but not ZO-2 in our cohort. There was significant correlation with another key TJ molecule, occludin (r=0.236, p=0.11). CLDN9, together with ZO-1 and ZO-3 significantly linked to the survival of patients (1444.6 months for the low expressing group versus 1138.2 months for the high expression group, p=0.013). The expression profile of the CLDN9/ZO1/ZO3 complex also indicated potential as an independent prognostic indicator (p=0.004, HR=2.033). The prognostic value was highly applicable to non-triple negative breast cancer patients. CLDN9 transcript also appeared to have a significant impact on treatment responses; patients who were sensitive to chemotherapies had a significantly lower levels of CLDN9 transcript than those who were resistant to treatment (p< 0.000001). In human cell lines, expression levels of CLDN-9 in ER (+) breast cancer cell lines, MDAMB361, MCF7 and BT474 were high; in a ER(-) breast cancer cell line MDAMB231, the expression level of CLDN-9 was lower. Conclusion. In conclusion, CLDN9 expression was differentially expressed in human breast cancer cells lines and appeared to reflect changes in ER status. It was apparent from levels of CLDN9 in a breast cancer cohort that expression was associated with grade and metastatic disease. Of significant notice was the finding that expression of CLDN9 in an expression profile with ZO1 and ZO3 has potential as a prognostic indicator, particularly in non-triple negative patients and in those who are chemotherapy resistant. Citation Format: Xinguo Zhuang, Wen G. Jiang, Eleri Davies, Bing Xu, Tracey A. Martin. Claudin-9 and its subcoat anchorage proteins ZO-1 and ZO-3 in breast cancer, the clinical and therapeutic significance [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P6-14-16.

Cycloartane triterpenoid from Euphorbia macrostegia modulates ER stress signaling pathways to induce apoptosis in MDA-MB231 and MCF-7 breast cancer cell lines.

Unfolded protein response (UPR) is involved in breast cancer (BC) progression and drug resistance. Many natural products (NPs) could modulate UPR and used for therapeutic purposes. Herein, we aimed to investigate the molecular mechanism of Cycloart-23E-ene-3β, 25-diol (Cycloart-E25), cytotoxicity, as a NP extracted from Euphorbia macrostegia and focused on endoplasmic-reticulum stress (ERS) and UPR signaling pathways. Reactive oxygen species (ROS) were probed by DCFDA fluorescence dye. Apoptosis was assayed by annexin V/propidium iodide (PI), immunoblotting of anti- and proapoptotic, Bcl-2 and Bax proteins, and mitochondrial transmembrane potential (ΔΨm) changes. Thioflavin T (ThT) staining and immunoblotting of UPR signaling components (CHOP, PERK, ATF6, BiP, and XBP1) were recruited for the assessment of ERS. Our results indicated that Cycloart-E25 noticeably increases ROS levels in both MB-231 MDA-MB-231 and MCF-7 cell lines, p>0.05. Flow cytometry assessments revealed an increase in the cell population undergoing apoptosis. Also, the Bax/Bcl-2 ratio increased in a dose-dependent manner following Cycloart-E25 treatment, significantly, p>0.05. Mitochondrial involvement could be deduced by significant decreases in ΔΨm, p>0.05. Cycloart-E25 potently induces protein aggregation and upregulated CHOP, PERK, ATF6, BiP, and XBP1 factors in both MDA-MB-231 MB-231 and MCF-7 cell lines, indicating the involvement of ERS in Cycloart-E25-mediated apoptosis. In conclusion, Cycloart-E25 increased the accumulation of misfolded proteins and upregulated UPR components. Therefore, induction of ERS may be involved in the trigger of apoptosis in BC cell lines. Cycloart-E25 induced apoptosis in breast cancer cell lines through ERS. More assessments are needed to confirm its in vivo anti-tumoral effects.

Design, synthesis and evaluation of novel 3-(substitutedphenyl)-2-(4-(substitutedphenyl) thiazol-2-yl)-2hpyrazolo [3, 4-d] thiazol-5(6h)-one derivatives as anti-breast cancer agents

Mainstream cancer research has continued to place a significant emphasis on the development of new and effective therapeutic candidates to tackle rising treatment resistance and off-target toxicities. Here, a series of novel 3-(substitutedphenyl)-2-(4-(substitutedphenyl)thiazol-2-yl)-2Hpyrazolo[3,4-d]thiazol-5(6H)-one derivatives were synthesized and characterized. The ability of the synthesized compounds to reduce the survival of the human breast cancer cell line MDA-MB 231 was evaluated. When compared to the reference chemical, 5-fluorouracil, 3-(4-chlorophenyl)-2-(4- (4-chlorophenyl)thiazol-2-yl)-2H-pyrazolo[3,4d]thiazol-5(6H)-oneand 3-(4-nitrophenyl)-2-(4-(4-nitrophenyl)thiazol-2-yl)-2H-pyrazolo[3,4d]thiazol5(6H)-oneshowed the highest inhibitory activity (IC50:550 0.78 M and 504 0.89, respectively) on the viability of MDA-MB 231 cells. A molecular docking study has been carried out to discover more potent drugs.

Suppression of G Protein-coupled Estrogen Receptor 1 (GPER1) Enhances the Anti-invasive Efficacy of Selective ERβ Agonists.

G protein-coupled estrogen receptor 1 (GPER1) is often over-expressed in triple negative breast cancer (TNBC). GPER1 is responsible for many of the non-genomic, membrane-initiated effects of estrogens. Therefore, we have analyzed the effects of GPER1 knockdown using specific siRNA. Transient GPER1 silencing was conducted using RNA interference and confirmed by RT-PCR and western blot. Viability of human breast cancer cell lines MDA-MB 231 and HCC 1806 was tested using AlamarBlue assay. Cell invasion was analyzed by assessment of cell migration rate through an artificial basement membrane in a modified Boyden chamber. Viability of both cell lines was slightly decreased after suppression of GPER1 expression. Knockdown of GPER1 resulted in a significantly reduced invasion of the TNBC cells. The anti-invasive effect of selective ERβ agonists was significantly stronger after knockdown of GPER1 expression. In addition, the efficacy of tamoxifen treatment was significantly increased after suppression of GPER1 expression. Suppression of GPER1 reduced the metastatic behavior of TNBC cells, improved the anti-invasive efficacy of selective ERβ agonists and sensitized cells to 4OH-tamoxifen.

Matrix metalloproteinase 2 is a target of the RAN-GTP pathway and mediates migration, invasion and metastasis in human breast cancer

RAS-related nuclear protein(RAN) is a nuclear shuttle and normally regulates events in the cell cycle. When overexpressed in cultured cells, it causes increases in cell migration/invasion in vitro and its overexpression is associated with early breast cancer patient deaths in vivo. However, the underlying mechanism is unknown. The effect of RAN overexpression on potential targets MMP2, ATF3, CXCR3 was investigated by Real-Time PCR/Western blots in the triple receptor negative breast cancer(TRNBC) cell line MDA-MB231 and consequent biological effects were measured by cell adhesion, cell migration and cell invasion assays. Results showed that knockdown of RAN lead to a reduction of MMP2 and its potential regulators ATF3 and CXCR3. Moreover, knockdown of ATF3 or CXCR3 downregulated MMP2 without affecting RAN, indicating that RAN regulates MMP2 through ATF3 and CXCR3. Knockdown of RAN and MMP2 reduced cell adhesion, cell migration and cell growth in agar, whilst overexpression of MMP2 reversed the knockdown of RAN. Furthermore, immunohistochemical staining for RAN and MMP2 are positively associated with each other in the same tumour and separately with patient survival times in breast cancer specimens, suggesting that a high level of RAN may be a pre-requisite for MMP2 overexpression and metastasis. Moreover, positive immunohistochemical staining for both RAN and MMP-2 reduces further patient survival times over that for either protein separately. Our results suggest that MMP2 expression can stratify progression of breast cancers with a high and low incidence of RAN, both RAN and MMP2 in combination can be used for a more accurate patient prognosis. Simple summaryRan is an important regulator of normal cell growth and behaviour. We have established in cell line models of breast cancer (BC) a molecular pathway between RAN and its protein-degrading effector MMP-2 and properties related to metastasis in culture. Using immunohistochemistry (IHC) staining of primary BCs, we have shown that RAN and MMP-2 are on their own significantly associated with patient demise from metastatic BC. Moreover, when staining for MMP-2 is added to that for RAN in the primary tumours, there is a significant decrease in patient survival time over that for either protein alone. Thus a combination of staining for RAN and MMP2 is an excellent marker for poor prognosis in breast cancer.