Estrogen Receptor Positive Cells Research Articles

Synthesis of 2,2-dimethyl-chroman-based stereochemically flexible and constrained anti-breast cancer agents

Receptors are proteinous macromolecules which remain in the apo form under normal/unliganded conditions. As the ligand approaches, there are specific stereo-chemical changes in the apo form of the receptor as per the stereochemistry of a ligand. Accordingly, a series of substituted dimethyl-chroman-based stereochemically flexible and constrained Tamoxifen analogs were synthesized as anti-breast cancer agents. The synthesized compounds 19a-e, 20a-e, 21, and 22a-e, showed significant antiproliferative activity against estrogen receptor-positive (ER+, MCF-7) and negative (ER-, MDA MB-231) cells within IC50 value 8.5–25.0 µM. Amongst all, four potential molecules viz 19b, 19e, 22a, and 22c, were evaluated for their effect on the cell division cycle and apoptosis of ER+ and ER- cancer cells (MCF-7 & MDA MB-231cells), which showed that these compounds possessed antiproliferative activity through triggering apoptosis. In-silico docking experiments elucidated the possible affinity of compounds with estrogen receptors-α and -β.

Abstract PO4-06-10: Targeting necroptosis in breast cancer induced by Ophiobolin A

Abstract Abstract Necroptosis or programmed necrosis is a form of cell death distinct from apoptosis. Necroptotic cells display the character of rounding of the cell, gain in cell volume, rupture of plasma membrane and release of intra-cellular contents. Although few key necroptosis regulators including receptor interacting protein kinase 3 (RIPK3) and mixed lineage kinase domain like pseudokinase (MLKL) has been identified, their role/mechanism in inducing cell death in triple-negative breast cancer (TNBC) which lack RIPK3 expression remains elusive. Ophiobolin A is a compound naturally made by fungus and potently kills cancer cells especially TNBC. Our current study investigated the cell death mechanism(s) induced by Ophiobolin A (natural product) in breast cancer cell lines. The mechanism of cell death elicited by OpA was analyzed by applying inhibitors for specific pathways including apoptosis, necroptosis, ferroptosis and paraptosis, by analyzing markers of cell death using flow cytometry and western blotting. The formation of necrosomes was analyzed with exogeneous expression of RIPK3 tagged with green fluorescence protein (GFP) in HeLa, MDA-MB-231, MDA-MB-468 cell lines which lacks endogenous RIPK3 expression and in MCF7 estrogen receptor (ER) positive cell line. OpA induced necrosome formation was identified by formation of puncta in TNBC and HeLa cells which lack RIP3 expression, however, necrosomes were not detectable in ER positive cells. Clinical relevance of RIPK3 and MLKL has been analyzed using bioinformatic tools. Effect of OpA In vivo has been analyzed using Immune compromised SCID mice. The data obtained in the present study indicates that OpA has an increased anticancer effect in TNBC compared to the estrogen receptor (ER) positive breast cancer cells. Cells having undergone EMT were shown to have more sensitivity towards OpA when compared to uninduced cell lines, which is sensitive to Necrostatin-1, an inhibitor of necroptosis. However, apoptosis, ferroptosis and paraptosis inhibitors failed to rescue cell death which clearly confirms that OpA induces necroptosis cell death pathway in EMT undergone cells. OpA treatment significantly increased puncta in TNBC compared non-TNBC cells, further confirming the necroptotic cell death in TNBC. Bioinformatic analysis revealed that RIPK3 is negatively corelated with breast cancer and has least over-all survival in patients who lack RIPK3 expression. OpA treatment showed a significant tumor regression in tumor bearing SCID mice. All together our findings identify that OpA induce necroptosis in EMT-enriched TNBC. The study further needs an in-depth analysis of molecular mechanism induced by OpA and involvement of EMT in necroptotic cell death. Citation Format: Tolulope Ojo, Santhalakshmi Ranganathan. Targeting necroptosis in breast cancer induced by Ophiobolin A [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 PO4-06-10.

Abstract PO4-20-11: Excellent Response to Trastuzumab Deruxtecan in “HER-2 Low” Leptomeningeal Breast Cancer and Diagnostic and Monitoring Utility of CNSide Assay

Abstract A 72-year-old female presented to the emergency department with sudden onset of imbalance and cognitive decline. Two years ago, she was diagnosed with stage III estrogen receptor (ER) positive, progesterone receptor (PR) negative and human epidermal growth factor receptor 2 (HER2) negative (immunohistochemistry score: 0) invasive breast cancer. She subsequently underwent lumpectomy, adjuvant radiation and chemotherapy. She had been taking adjuvant letrozole at the time of presentation. Magnetic resonance imaging (MRI) of the brain showed obstructive hydrocephalus without any parenchymal lesion or leptomeningeal enhancement. MRI of spine, computerized tomography of chest/abdomen/pelvis and bone scan were unrevealing except a left adrenal mass which was equivocal for metastasis. Cerebrospinal fluid (CSF) analysis showed rare malignant cells. Based on the morphology of malignant cells and the patient’s prior history of breast cancer, the diagnosis of leptomeningeal disease with breast primary was made. There were insufficient cells for additional studies. CNSide, a microfluidic platform that uses antibody capture method to detect CSF tumor cells, showed 4678 tumor cells per milliliter (ml) of CSF. Immunocytochemistry of these cells showed that the cells were ER negative (criterion: < 2.6% ER positive cells) and programmed cell death ligand 1 (PD-L1) negative (criterion: < 3.4% PD-L1 positive cells). Fluorescence in situ hybridization (FISH) testing showed 22% of tumor cells with HER2 amplification (either HER2 to CEP17 ratio >/= 2.0 or HER2 copy number >/= 6). She underwent ventriculoperitoneal (VP) shunt placement with complete recovery of her neurological symptoms. Five weeks later, she was started on trastuzumab deruxtecan (T-DXd) mainly because of the HER2 FISH results from CNSide. She did not receive central nervous system(CNS) irradiation due to complete resolution of neurological symptoms with VP shunt placement. After two cycles of T-DXd, MRI brain showed mild leptomeningeal enhancement along bilateral superior cerebellar sulci. Positron emission tomography/computed tomography(PET/CT) scan showed a new sclerotic rib focus, thought to represent treatment response. It also showed decrease in size of the adrenal mass. The adrenal mass was hypermetabolic on PET, consistent with malignancy. CSF cytology was negative, while CSF tumor cell count significantly reduced to 6.72 cells/ml using CNSide. There were no new neurological symptoms. Despite MRI brain findings, she was continued on T-DXd given overall favorable clinical, radiological and CSF data. After 7th cycle of T-DXd, repeat CSF cytology continued to remain negative, CNSide CSF tumor cell count decreased further to 6.27 cells/ml, MRI brain showed interval resolution of prior leptomeningeal enhancement, CT scan showed further decrease in size of the adrenal mass (baseline 5.4cm to 3cm), stable rib sclerotic lesion and no additional metastatic lesion. To date, she has undergone eight cycles of T-DXd which has effectively controlled her disease for a period of seven months. She has not needed VP shunt revision and continues to do well. To our knowledge, this is the first case demonstrating the activity of T-DXd against CSF tumor cells where a small subset exhibited HER2 amplification. This case also highlights the benefits of using advanced and highly sensitive CSF assays to diagnose and surveil leptomeningeal disease and to assess HER2 signaling. This case is well-timed especially in the era of next-generation, CNS penetrating, potent HER2-directed antibody-drug conjugate like T-DXd which can mount antitumor activity even with minimal HER2 expression in tumors. Citation Format: Sarah Stanford, Zeni Kharel, Lauryn Hemminger, Tyler Schmidt, Sara Hardy, Jason Zittel, Nimish Mohile, Ajay Dhakal. Excellent Response to Trastuzumab Deruxtecan in “HER-2 Low” Leptomeningeal Breast Cancer and Diagnostic and Monitoring Utility of CNSide Assay [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 PO4-20-11.

Abstract PO1-24-04: Gedatolisib, a pan-PI3K/mTOR inhibitor, shows superior potency and efficacy relative to other PI3K/AKT/mTOR pathway inhibitors in breast cancer models

Abstract Background: The PI3K, AKT, and mTOR (PAM) pathway is frequently activated in breast cancer (BC). Current standard-of-care therapy options for patients with advanced BC (ABC) include PAM inhibitors (PAMi), such as everolimus and alpelisib, and hormonal therapy, such as letrozole and fulvestrant. Most PAMi selectively inhibit one or only a few PAM pathway components, which can lead to drug resistance. To minimize drug resistance, a more comprehensive inhibition of the multiple PI3K isoforms and downstream mTOR complexes may be required. We hypothesized that gedatolisib, which potently inhibits all Class I PI3K isoforms, as well as mTORC1 and mTORC2, can be more effective in BC cells than a PAMi targeting single PAM pathway components. Methods: A panel of BC cell lines with mutated or non-mutated PAM pathway genes (PIK3CA, PTEN, AKT) were evaluated for their sensitivity to gedatolisib and other PAMi (PI3K-α: alpelisib; AKT: capivasertib; mTORC1: everolimus; pan-PI3K/mTOR: gedatolisib). Cell viability, growth rate inhibition, and cell death were evaluated by luciferase- and fluorescence-based assays, both in monolayer cultures and three-dimensional (3D) cultures on reconstituted basement membrane. Flow cytometry analytical assays were conducted to assess DNA synthesis (EdU incorporation), protein synthesis (OPP incorporation), and PAM pathway activity (RPS6 and 4EBP1 phosphorylation). BC xenograft studies evaluating gedatolisib in vivo were also performed. Results: Gedatolisib strongly inhibited PAM pathway activity and reduced cell viability and growth rate in the cell lines tested. Compared to the other PAMi, gedatolisib exhibited more potent and efficacious anti-proliferative and cytotoxic effects, regardless of the cell lines’ PI3K pathway mutational status. Gedatolisib effects were confirmed in 3D culture on reconstituted basement membrane, where gedatolisib inhibited tumor cell spheroid growth and induced regression. Mechanistically, gedatolisib decreased both DNA and protein synthesis more effectively than the other PAMi tested. Gedatolisib also exerted superior anti-proliferative and cytotoxic effects relative to the other PAMi tested in estrogen receptor-positive BC cell lines concomitantly treated with fulvestrant. BC xenografts confirmed growth inhibitory effects of gedatolisib in vivo. Conclusions: The pan-PI3K/mTOR inhibitor, gedatolisib, may more effectively address potential drug resistance mechanisms associated with narrowly targeted PAM inhibitors. Gedatolisib has previously demonstrated promising preliminary clinical efficacy and safety data in ABC in combination with hormonal therapy. A Phase 3 study (VIKTORIA-1) evaluating gedatolisib plus fulvestrant with and without palbociclib is underway in patients with ABC. Citation Format: Stefano Rossetti, Aaron Broege, Adrish Sen, Salmaan Khan, Ian MacNeil, Jhomary Molden, Igor Gorbatchevsky, Brian F. Sullivan, Lance Laing. Gedatolisib, a pan-PI3K/mTOR inhibitor, shows superior potency and efficacy relative to other PI3K/AKT/mTOR pathway inhibitors in breast cancer models [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 PO1-24-04.

Abstract PO3-24-09: May ESR1 mutant breast cancer cells influence fibroblast phenotype?

Abstract For almost 50 years, it has been postulated that carcinogenesis relies on the intrinsic genetic abnormalities of tumor cells, but in the last decades, it has been reported that their functional interactions with the tumor microenvironment (TME) might affect therapy response and contribute to the disease progression. Based on these observations, the aim of the present study was to investigate the functional interactions between one of the essential components of TME, the fibroblasts, and breast cancer (BC) cells, expressing mutations in the hormone-binding domain (HBD) of the gene encoding for the estrogen receptor alpha (ESR1). Thus, we employed estrogen receptor-positive MCF-7 BC cells CRISPR engineered to express the Y537S-HBD mutation. Y537S is the most commonly detected mutation harbored in HBD-ESR1 and is a major contributor to endocrine therapy resistance and poor clinical outcome in BC. We collected conditioned media (CM) from BC cells and fibroblasts isolated from primary human tissues (normal fibroblasts, NFs, and cancer-associated fibroblasts, CAFs) in order to assess in vitro co-culture systems that can mimic the complex in vivo TME. It was interesting to observe that CAFs displayed a significant increase in their proliferation and migration when exposed to CM of mutant BC cells with respect to the parental ones. These latter findings fit with the immunofluorescence analysis showing a more evident formation of actin stress fibers. However, proteomic analysis demonstrated, in the same circumstances, more significant changes in NFs than in CAFs. Among the up-regulated proteins revealed by NFs upon Y537S-CM exposure, most of them overlap the up-regulated proteins featuring the intrinsic phenotype of CAFs, mainly involved in the cellular ultrastructural organization (i.e. cytoskeleton, focal adhesion, vesicle, and organelle) as evidenced by Metacore functional analysis. On the other side, we demonstrated that mutant clones showed more aggressive behavior in terms of proliferation, growth, migration, and invasion, compared to the parental counterpart upon exposure to the CM-derived from NFs and CAFs. This led us to further investigate the intrinsic properties of the mutated clones through their genomic and proteomic profiles that evidenced, by using Metacore software, an enrichment of insulin-like growth factor 1 receptor (IGF1R) pathway. The relevance of the latter datum was confirmed by the higher content of the IGF-1 ligand found in the secretome of mutant cells. Thus, the short autocrine loop maintaining IGF1/IGF1R signaling activation in mutant clones might reasonably play an important role in mediating the autocrine and paracrine effects between mutant cells and fibroblasts. For instance, the pharmacological blockade of IGF1R signaling interfered with the reciprocal interactions between fibroblasts and BC cells that sustained tumor growth and progression as evidenced in both “in vitro” and “in vivo” experiments. In conclusion, our study addressed the IGF1R pathway as a potential druggable target helpful to disconnect mutant breast cancer cell-fibroblast crosstalk that potentiates breast tumor growth and progression. Citation Format: Luca Gelsomino, Amanda Caruso, Rocco Malivindi, Adel Elisabetta Leonetti, Emine Tasan, Salvatore Panza, Giuseppina Daniela Naimo, Ines Barone, Cinzia Giordano, Daniela Bonofiglio, Loredana Mauro, Guowei Gu, Suzanne Fuqua, Stefania Catalano, Sebastiano Andò. May ESR1 mutant breast cancer cells influence fibroblast phenotype? [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 PO3-24-09.

Carcinoma of unkown primary, presenting as estrogen receptor positive small cell carcinoma of breast without a breast lesion – case report on a rare entity

Carcinoma of unkown primary, presenting as estrogen receptor positive small cell carcinoma of breast without a breast lesion – case report on a rare entity

Abstract 5861: CDK4/6 therapy-induced senescence as a resistance mechanism-MiDAS touch

Abstract Background: Cyclin-dependent kinase inhibitors (CDK4/6i) have revolutionized the therapy for estrogen receptor positive (ER+) breast cancer. Despite the response to CDK4/6i, resistance and recurrence are still a clinical reality, resulting in death due to breast cancer. G1 cell cycle arrest has been considered as the main mechanism of action of CDK4/6i in luminal breast cancer. However, the response to therapy does not correlate with the expression of CDK4/6 or key cell cycle proteins. It is also unclear whether CDK4/6i-induced senescence enhances the therapeutic response or mediates development of resistance. Experimental Procedures: We have developed drug-tolerant persisters resistant to CDK4/6 inhibitors (CDK4/6i-DTPs) in a panel of estrogen receptor positive (ER+) cells to explore the molecular mechanisms associated with resistance. Using different cell phenotype assays (i.e., cell viability/cell cycle, senescence/senescence reversibility and wound healing) as well as senescence-associated secretory phenotype (SASP) human cytokine array of 105 markers, we characterized the phenotype and secretome of these CDK4/6i DTPs. Summary: CDK4/6i-DTPs induced by abemaciclib, palbociclib and ribociclib (all from Selleckchem) demonstrated resistance to these drugs and dramatically slowed growth. The percentage of senescent cells reached 30-89% of the total population for all cell lines in all three drugs, whereas control parental cells exhibited around 10%. CDK4/6i DTPs also exhibited significant cell migration, and increased lysosomal phenotype compared to their parental sensitive cells. Further analysis with human cytokine array revealed that protein levels of growth differentiation factor 15 (GDF-15) are elevated in both cell lysates and conditioned-media of CDK4/6i DTPs, whereas Serpin E1 (Plasminogen Activator Inhibitor, Type I, PAI-1) was unique to secreted CDK4/6i DTPs. Interestingly, we did not observe changes in pro-inflammatory senescence-associated secretory phenotype (SASP) markers such as interleukins. Apart from being a SASP protein, GDF-15 is a mitochondrial cytokine (mitokine), suggesting a role in mitochondrial dysfunction-associated senescence (MiDAS). HMGB1, and LMNB1 are also down-regulated in CDK4/6-DTPs supporting the MiDAS phenotype. CDK4/6i-induced MiDAS appears to be transient, as CDK4/6i-DTPs reverted to the parental phenotype in drug-free culture media 20 days after the removal of CDK4/6i's. This included growth characteristics and sensitivity to CDK4/6i. This reversion of phenotype was observed in all five cell line models tested with all three drugs. Conclusions: CDK4/6-induces a mitochondrial dysfunction-associated senescence (MiDAS). This appears to be transient in nature as withdrawal of the drug results reacquisition of parental cell phenotype and drug-sensitivity. Targeting MiDAS pathway might be critical to improve efficacy of CDK4/6 inhibitors. Citation Format: Yesim Gokmen-Polar, Yuan Gu, Ling Ruan, Sunil S. Badve. CDK4/6 therapy-induced senescence as a resistance mechanism-MiDAS touch [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 5861.

Abstract 4142: Obesity contributes to CD8+ T cell dysfunction before and after lung metastasis in a mouse model of ER+ breast cancer

Abstract Obesity is known to worsen the overall prognosis of breast cancer patients. Breast cancer patients with a body mass index (BMI) of ≥30 kg/m2 have an increased risk for metastatic disease compared to patients with a BMI in the normal range. Although immune cells like neutrophils and myeloid derived suppressor cells have been studied in breast cancer metastasis of the lung, little is known how T cell populations change before and after metastasis. To investigate these gaps, we fed 3-week-old female FVB/N mice either a low-fat diet (LFD) or high-fat diet (HFD) for 16 weeks to induce obesity. One group was set as a tumor-naïve control and the other was injected estrogen receptor positive (ER+) TC2 cells into the mammary fat pad. Tumors grew to 0.5 cm in diameter then were surgically removed. Lung tissue was collected 8 weeks after tumor removal to examine progression of metastatic disease, and T cell populations were quantified in tumor-naïve and metastatic lung tissue from obese and lean mice using flow cytometry. Lungs from naïve obese mice showed a significant increase of total CD45+ immune cells. CD8+ T cells from naive obese mice expressed higher levels of programmed cell death protein-1 (PD1), a marker of T cell dysfunction or T cell activation. Metastatic lungs also showed increases in CD45+ immune cells and PD-1+ expression on CD3+ cells and CD8+ cells. Overall, metastatic lungs showed higher levels of PD-1 expression than naïve lungs on more cell types, evidence of more immune dysfunction or activation. To further investigate how obesity alters the function of T cells, CD45+ cells were sorted from lungs from lean and obese mice with and without metastasis, and gene expression was examined using the NanoString nCounter Immune Exhaustion panel. Immune cells from the lungs of obese non-tumor-bearing mice showed increased expression of markers for increased TCR signaling. This may indicate more T cell activation which leads to exhaustion in obese naïve mice. In metastatic lungs from obese mice, immune cells showed impaired interferon and tumor necrosis factor signaling. In addition, immune cells from metastatic lungs of obese mice also had upregulated expression of genes associated with senescence which may indicate a combination of both exhaustion and senescent phenotypes are present. This was not seen in immune cells from naïve samples, indicating that obesity leads to more chronic T cell dysfunction in metastatic lungs. Overall, even without pathogenic interference, obesity contributes to more T cell signaling and impaired CD8+ T cell activation that leads to higher T cell dysfunction once metastasis is present. Citation Format: Abbey E. Williams, Lisa M. Arendt. Obesity contributes to CD8+ T cell dysfunction before and after lung metastasis in a mouse model of ER+ breast cancer [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 4142.

A modular microfluidic platform to study how fluid shear stress alters estrogen receptor phenotype in ER+ breast cancer cells

Metastatic breast cancer leads to poor prognoses and worse outcomes in patients due to its invasive behavior and poor response to therapy. It is still unclear what biophysical and biochemical factors drive this more aggressive phenotype in metastatic cancer; however recent studies have suggested that exposure to fluid shear stress in the vasculature could cause this. In this study a modular microfluidic platform capable of mimicking the magnitude of fluid shear stress (FSS) found in human vasculature was designed and fabricated. This device provides a platform to evaluate the effects of FSS on MCF-7 cell line, an estrogen receptor positive (ER+) breast cancer cell line, during circulation in the vessels. Elucidation of the effects of FSS on MCF-7 cells was carried out utilizing two approaches: single cell analysis and bulk analysis. For single cell analysis, cells were trapped in a microarray after exiting the serpentine channel and followed by immunostaining on the device (on-chip). Bulk analysis was performed after cells were collected in a microtube at the outlet of the microfluidic serpentine channel for western blotting (off-chip). It was found that cells exposed to an FSS magnitude of 10 dyn/cm2 with a residence time of 60 s enhanced expression of the proliferation marker Ki67 in the MCF-7 cell line at a single cell level. To understand possible mechanisms for enhanced Ki67 expression, on-chip and off-chip analyses were performed for pro-growth and survival pathways ERK, AKT, and JAK/STAT. Results demonstrated that after shearing the cells phosphorylation of p-AKT, p-mTOR, and p-STAT3 were observed. However, there was no change in p-ERK1/2. AKT is a mediator of ER rapid signaling, analysis of phosphorylated ERα was carried out and no significant differences between sheared and non-sheared populations were observed. Taken together these results demonstrate that FSS can increase phosphorylation of proteins associated with a more aggressive phenotype in circulating cancer cells. These findings provide additional information that may help inform why cancer cells located at metastatic sites are usually more aggressive than primary breast cancer cells.

Effects of targeting highly expressed in cancer protein 1 (Hec1) inhibitor INH 1 in breast cancer cell lines In Vitro.

In the present study, the in vitro antiproliferative effect of targeting highly expressed cancer protein 1 (Hec1) inhibitor INH1 was investigated in estrogen receptor-positive MCF-7 cell line originating from an in situ carcinoma and triple negative MDA-MB-231 cell line originating from metastatic carcinoma. Cell viability, xCELLigence RTCA DP instrument CI values, MI, BrdU proliferation assay, and AI analyses were employed for this purpose. According to the findings of the current study, INH1 altered cell proliferation by lowering cell viability, CI, MI values, and BrdU proliferation while raising AI values in both cell lines. Between the experimental and control groups, there were noticeable changes (p<0.05). These findings imply that INH1's mode of action is not dependent on the presence of estrogen receptors, making it a potentially effective therapy for breast cancer.

Progestins and breast cancer hallmarks: The role of the ERK1/2 and JNK pathways in estrogen receptor positive breast cancer cells

Progestins used in hormonal contraceptives and menopausal hormone therapy (MHT) have been linked to increased breast cancer risk. Whether the association holds for all progestins is unclear and the underlying mechanisms remain poorly understood. We directly compared the effects of four progestins (medroxyprogesterone acetate (MPA), norethisterone acetate (NET-A), levonorgestrel (LNG) and drospirenone (DRSP)) to each other and the natural progestogen progesterone (P4) on selected cancer hallmarks. To provide mechanistic insight into these effects, we assessed the role of the progesterone receptor (PR), and the extracellular signal-related kinase (ERK1/2) and c-Jun N terminal (JNK) signaling pathways. We showed that the increased proliferation of the luminal T47D breast cancer cell line by P4 and all progestins, albeit to different extents, was inhibited by PR knockdown and inhibition of both the ERK1/2 and JNK pathways. While knockdown of the PR also blocked the upregulation of MKI67 and CCND1 mRNA expression by selected progestogens, only a role for the ERK1/2 pathway could be established in these effects. Similarly, only a role for the ERK1/2 pathway could be confirmed for progestogen-induced colony formation, whereas both the ERK1/2 and JNK pathways were required for cell migration in response to the three older progestins implicated in the etiology of breast cancer, MPA, NET-A and LNG. Together our results show that all the progestins elicit their effects on cell proliferation via a mechanism requiring the PR, ERK1/2 and JNK pathways. While the ERK1/2 and JNK pathways are also required for increased cell migration by the older progestins, only a role for the ERK1/2 pathway could be established in their effects on colony formation. Notably, the cytoplasmic PR was not needed for activation of the ERK1/2 pathway by the progestogens. Given that DRSP showed significantly lower proliferation than MPA and NET-A, and that it had no effect on breast cancer cell migration and colony formation, hormonal formulations containing the newer generation progestin DRSP may provide a better benefit/risk profile towards breast cancer than those containing the older generation progestins.

Orai1α and Orai1β support calcium entry and mammosphere formation in breast cancer stem cells

Orai1 is the pore-forming subunit of the Ca2+-release activated Ca2+ channels that mediate store-operated Ca2+ entry (SOCE) in excitable and non-excitable cells. Two Orai1 forms have been identified in mammalian cells, the full-length variant Orai1α, and the short form Orai1β, lacking the N-terminal 63 amino acids. Stem cells were isolated from non-tumoral breast epithelial cells of the MCF10A cell line, and the most representative ER+ , HER2 or triple negative breast cancer cell lines MCF7, SKBR3 and MDA-MB-231, respectively. Orai and TRPC family members expression was detected by RT-PCR and Western blotting. Changes in cytosolic Ca2+ concentration were analyzed by confocal microscopy using Fluo 4 and the spheroid-forming ability and self-renewal was estimated in culture plates coated with pHEMA using a cell imaging system. Here, we have characterized the expression of Orai family members and several TRPC channels at the transcript level in breast stem cells (BSC) derived from the non-tumoral breast epithelial cell line MCF10A and breast cancer stem cells (BCSC) derived from the well-known estrogen receptor positive (ER+), HER2 and triple negative cell lines MCF7, SKBR3 and MDA-MB-231, respectively. Furthermore, we have evaluated the mammosphere formation efficiency and self-renewal of the BSC and BCSC. Next, through a combination of Orai1 knockdown by iRNA and the use of MDA-MB-231 KO cells, missing the native Orai1, transfected with plasmids encoding for either Orai1α or Orai1β, we show that Orai1 is essential for mammosphere formation and self-renewal efficiency in BCSC derived from triple negative and HER2 subtypes cell cultures, while this channel has a negligible effect in BCSC derived from ER+ cells as well as in non-tumoral BSC. Both, Orai1α, and Orai1β support SOCE in MDA-MB-231-derived BCSC with similar efficiency, as well as COX activation and mammosphere formation. These findings provide evidence of the functional role of Orai1α and Orai1β in spheroid forming efficiency and self-renewal in breast cancer stem cells.

Mahanine mediated therapeutic inhibition of estrogen receptor-α and CDK4/6 expression, decipher the chemoprevention-signaling cascade in preclinical model of breast cancer

Ethnopharmacological relevanceMahanine (MH), a naturally occurring carbazole alkaloid, isolated from Ayurvedic medicinal plant Murraya koenigii (L.) Spreng, has been shown to have various pharmacological properties, including its inhibitory activity against different breast cancers (BC) subtypes. Aim of the studyWhile MH triggers apoptosis in BC cells regardless of subtype, the specific mechanism of MH action is not fully understood. In this study, we show the effect of MH in preventing BC progression by inducing apoptosis in relation to estrogen receptor-α (ERα) and cell cycle regulatory proteins. Materials and methodsTo assess the pharmacological activity in various in vitro and in vivo tests, isolated and pure MH was used. To conclude the study, cutting edged molecular biology techniques including Western blot analysis, enzyme-linked immunosorbent assay (ELISA), molecular simulation study, and other related software analysis were employed. ResultsMH demonstrated dose dependent cell viability against drug sensitive (MCF-7 and MDA-MB-231) and paclitaxel resistant (MCF-7TR and MDA-MB-231TR) BC cells. MH also exhibited synergistic activity with tamoxifen (TAM) against estrogen receptor positive (ER+) BC cells by inhibiting ERα expression in MCF-7 cells and N-Methyl-N-nitrosourea (MNU)-induced mammary tumor in a dose-dependent manner while having no effect on vinculin expression. In addition, MH inhibited cell cycle regulatory genes namely CDK1/CDK4/CDK6/CDC25A and neo-angiogenesis through downregulation of CD31/PECAMs in MCF-7, MDA-MB-231 cells and mammary tumors from MNU-induced rats. MH therapy has been shown to be significantly able to lower the serum leptin level and to be beneficial against the initiation of tumor development in SD rats for up to 12 weeks. Molecular modeling study revealed that MH has antagonized the effectiveness of several types of estrogen those bind to the ERα and has comparable binding efficacy to TAM. ConclusionOverall, the current investigation showed the ability of MH to modify cell cycle genes especially CDK4 and CDK6 might be responsible for its anticancer activity against different breast cancer subtypes. Additionally, this study will aid in advancing MH translational research to the clinical trial stage.

THU498 Establishing The Link Between Glucocorticoid Signaling And The Circadian Regulator DEC1 In Breast Cancer

Abstract Disclosure: M.I. Castro: None. W.S. Ybañez: None. P.D. Bagamasbad: None. Epidemiological studies have linked altered circadian rhythms due to irregular shift work, chronic jet lag, and heightened night-time light exposure to increased breast cancer (BCa) pathogenesis. Dysregulated glucocorticoid (GC; CORT) signaling in BCa may further promote chronodisruption by directly regulating the cyclic expression of clock genes found in the breast. The differentiated embryo-chondrocyte expressed gene 1 (DEC1; also known as STRA13/SHARP2/ BHLHB2) is a transcription factor involved in the regulation of circadian rhythmicity and tumor progression of several cancer types including the breast and associated with hormone receptor signaling in BCa. In this study, we explored the involvement of DEC1 in the crosstalk between GC signaling and the circadian axis in BCa. To establish DEC1 expression pattern in BCa tumor samples, we assessed publicly available RNA-seq datasets from the Genotype-Tissue Expression Project and found no significant difference in DEC1 expression in tumors when compared to normal tissue controls. However, when tumor samples were stratified into molecular subtypes based on transcriptomic data from the Cancer Genome Atlas, DEC1 expression was significantly downregulated in triple-negative BCa (TNBC) in comparison to luminal subtypes. This pattern of expression was reflected in the BCa cell lines where we observed higher DEC1 expression in the estrogen receptor-positive MCF7 cells relative to nontumorigenic triple-negative MCF10A cells and the highly aggressive TNBC MDA-MB-231 cell line. To determine if DEC1 is regulated by GCs in the breast, we treated non-tumorigenic breast epithelial MCF10A cells and the TNBC MDA-MB-231 cells with increasing concentrations of CORT and observed that DEC1 mRNA expression decreases in response to increasing concentrations of CORT. Treatment of MCF10A and MDA-MB-231 cells with GC receptor (GR)- specific agonist RU486 abolished the GC-dependent repression of DEC1 expression and this pattern of DEC1 expression persisted even in the presence of the protein synthesis inhibitor cycloheximide, suggesting that DEC1 is a direct transcriptional target of GR in mammary epithelial cells. Through in silico analysis of publicly available ChIP-sequencing datasets from BCa cell lines, we identified multiple CORT-responsive cis-regulatory elements in the DEC1 locus that could mediate the CORT-dependent repression of DEC1 expression. Lentiviral knockdown of DEC1 in three breast epithelial cell lines was generated and will be used in cancer hallmark assays on proliferation, apoptosis, survival, and migration to assess the functional role of DEC1 in BCa. Taken together, our data will contribute to understanding the combined effect of GC signaling and circadian gene regulation towards BCa progression. Presentation: Thursday, June 15, 2023

2-Methoxyestradiol as an Antiproliferative Agent for Long-Term Estrogen-Deprived Breast Cancer Cells.

To identify effective treatment modalities for breast cancer with acquired resistance, we first compared the responsiveness of estrogen receptor-positive breast cancer MCF-7 cells and long-term estrogen-deprived (LTED) cells (a cell model of endocrine therapy-resistant breast cancer) derived from MCF-7 cells to G-1 and 2-methoxyestradiol (2-MeO-E2), which are microtubule-destabilizing agents and agonists of the G protein-coupled estrogen receptor 1 (GPER1). The expression of GPER1 in LTED cells was low (~0.44-fold), and LTED cells displayed approximately 1.5-fold faster proliferation than MCF-7 cells. Although G-1 induced comparable antiproliferative effects on both MCF-7 and LTED cells (IC50 values of >10 µM), 2-MeO-E2 exerted antiproliferative effects selective for LTED cells with an IC50 value of 0.93 μM (vs. 6.79 μM for MCF-7 cells) and induced G2/M cell cycle arrest. Moreover, we detected higher amounts of β-tubulin proteins in LTED cells than in MCF-7 cells. Among the β-tubulin (TUBB) isotype genes, the highest expression of TUBB2B (~3.2-fold) was detected in LTED cells compared to that in MCF-7 cells. Additionally, siTUBB2B restores 2-MeO-E2-mediated inhibition of LTED cell proliferation. Other microtubule-targeting agents, i.e., paclitaxel, nocodazole, and colchicine, were not selective for LTED cells. Therefore, 2-MeO-E2 can be an antiproliferative agent to suppress LTED cell proliferation.

The TGFBI gene and protein expression in topotecan resistant ovarian cancer cell lines

PurposeThe primary limiting factor in achieving cures for patients with cancer, particularly ovarian cancer, is drug resistance. The mechanisms of drug resistance of cancer cells during chemotherapy may include compounds of the extracellular matrix, such as the transforming growth factor-beta-induced protein (TGFBI). In this study, we aimed to analyze the TGFBI gene and protein expression in different sensitive and drug-resistant ovarian cancer cell lines, as well as test if TGFBI can be involved in the response to topotecan (TOP) at the very early stages of treatment. Materials and methodsIn this study, we conducted a detailed analysis of TGFBI expression in different ovarian cancer cell lines (A2780, A2780TR1, A2780TR2, W1, W1TR, SKOV-3, PEA1, PEA2 and PEO23). The level of TGFBI mRNA (QPCR), intracellular and extracellular protein (Western blot analysis) were assessed in this study. ResultsWe observed upregulation of TGFBI mRNA in drug-resistant cell lines and estrogen-receptor positive cell lines, which was supported by overexpression of both intracellular and extracellular TGFBI protein. We also showed the TGFBI expression after a short period of treatment of sensitive ovarian cancer cell lines with TOP. ConclusionThe expression of TGFBI in ovarian cancer cell lines suggests its role in the development of drug resistance.

Social isolation and breast cancer.

Although the role of life-stressors in breast cancer remains unclear, social isolation is consistently associated with increased breast cancer risk and mortality. Social isolation can be defined as loneliness or an absence of perceived social connections. In female mice and rats, social isolation is mimicked by housing animals one per cage. Social isolation causes many biological changes, of which an increase in inflammatory markers and disruptions in mitochondrial and cellular metabolism are commonly reported. It is not clear how the two traditional stress-induced pathways, i.e., hypothalamic-pituitary axis (HPA), resulting a release of glucocorticoids from the adrenal cortex, and autonomic nervous system (ANS), resulting a release of catecholamines from the adrenal medulla and post-ganglionic neurons, could explain the increased breast cancer risk in socially isolated individuals. For example, glucocorticoid receptor activation in estrogen receptor positive breast cancer cells inhibits their proliferation, and activation of β-adrenergic receptor (β-AR) in immature immune cells promotes their differentiation towards anti-tumorigenic T cells. However, activation of HPA and ANS pathways may cause a disruption in the brain-gut-microbiome axis, resulting gut dysbiosis. Gut dysbiosis, in turn, leads to an alteration in the production of bacterial metabolites, such as short chain fatty acids, causing a systemic low-grade inflammation and inducing dysfunction in mitochondrial and cellular metabolism. A possible causal link between social isolation -induced increased breast cancer risk and mortality and gut dysbiosis should be investigated, as it offers new tools to prevent breast cancer.

Cell type and stage specific transcriptional, chromatin and cell-cell communication landscapes in the mammary gland

The mammary gland (MG) is composed of three main epithelial lineages, the basal cells (BC), the estrogen receptor (ER) positive luminal cells (ER+ LC), and the ER negative LC (ER− LC). Defining the cell identity of each lineage and how it is modulated throughout the different stages of life is important to understand how these cells function and communicate throughout life. Here, we used transgenic mice specifically labelling ER+ LC combined to cell surface markers to isolate with high purity the 3 distinct cell lineages of the mammary gland and defined their expression profiles and chromatin landscapes by performing bulk RNAseq and ATACseq of these isolated populations in puberty, adulthood and mid-pregnancy. Our analysis identified conserved genes, ligands and transcription factor (TF) associated with a specific lineage throughout life as well as genes, ligands and TFs specific for a particular stage of the MG. In summary, our study identified genes and TF network associated with the identity, function and cell-cell communication of the different epithelial lineages of the MG at different stages of life.

Chayote leaves display seasonal variation in phytoestrogenic activities and phenolic content

Chayote (Sicyos edulis Jacq.) is a popular vegetable in the Philippines and has been recognized for its nutritional value and bioactive compounds, including phenolic acids found in its edible parts. Hence, this study sought to determine whether extracts from S. edulis shoots can elicit a bioactive estrogenic response. Specifically, the study determined whether the location of cultivation or monsoon season of collection would influence the estrogenic activities of S. edulis extracts. Here, we found that a specific fraction (F5.6) of S. edulis shoots isolated through solid-phase extraction (C-18 and HLB) inhibited the transactivation of an estrogen-induced luciferase reporter gene in an estrogen receptor-positive cell line T47D without affecting cell viability, independently of the farm source and the season of sample collection. This inhibition was also seen in the E2- induced expression of superoxide dismutase 2 (SOD2), an antioxidant enzyme upregulated in advanced breast cancer cells. In contrast, the phenolic content in the F5.6 fraction varied across seasons, with a higher content found during the northeast monsoon season (0.175 ± 0.027 mg GAE/mg sample) than the southwest monsoon seasons (0.043 ± 0.015 and 0.051 ± 0.012 mg GAE/mg sample). The high phenolic content increased the ratio of estrogen receptor alpha to beta transcripts and the mRNA expression level of the estrogen-responsive gene, growth regulation by estrogen in breast cancer 1 (GREB1A), in T47D cells. Overall, this study showed how seasonal variation may affect the phenolic content of S. edulis and influence the plant’s bioactivity, providing a potential cultivation strategy in obtaining extracts with the intended bioactivity.

Pharmacological inhibition of neuropeptide Y receptors Y1 and Y5 reduces hypoxic breast cancer migration, proliferation, and signaling

BackgroundNeuropeptide Y (NPY) is an abundant neurohormone in human breast carcinomas that acts on a class of G-protein coupled receptors, of which NPY1R and NPY5R are the most highly expressed. This abundance is exploited for cancer imaging, but there is interest in pharmacological inhibition of the NPYRs to interrogate their functional relevance in breast cancer. We previously reported that NPY1R and NPY5R mRNA abundance is increased by hypoxia inducible factors, which sensitizes these receptors to NPY stimulation leading to enhanced migration and proliferation.Methods/ResultsHere, we measured the effects of NPY1R and NPY5R antagonists in normoxia and hypoxia on migration, proliferation, invasion, and signaling in 2D and 3D models of breast cancer cell lines MDA-MB-231 and MCF7. Antagonizing NPY1R and/or NPY5R in hypoxia compared to normoxia more greatly reduced MAPK signaling, cell proliferation, cell migration and invasion, and spheroid growth and invasion. The estrogen receptor positive MCF7 cells were significantly less invasive in 3D spheres when NPY5R was specifically inhibited. There were some discrepancies in the responses of each cell line to the isoform-specific antagonists and oxygen availability, therefore further investigations are required to dissect the intricacies of NPYR signaling dynamics. In human breast tumor tissue, we show via immunofluorescence that NPY5R protein levels and colocalization with hypoxia correlate with advanced cancer, and NPY1R protein correlates with adverse outcomes.ConclusionsAntagonizing the NPYRs has been implicated as a treatment for a wide variety of diseases. Therefore, these antagonists may aid in the development of novel cancer therapeutics and patient-based treatment plans.