Differentiation Of Breast Cancer Cells Research Articles

Discovery of Novel ERα and Aromatase Dual-Targeting PROTAC Degraders to Overcome Endocrine-Resistant Breast Cancer.

Estrogen receptor α (ERα) plays a pivotal role in the proliferation, differentiation, and migration of breast cancer (BC) cells, and aromatase (ARO) is a crucial enzyme in estrogen synthesis. Hence, it is necessary to inhibit estrogen production or the activity of ERα for the treatment of estrogen receptor-positive (ER+) BC. Herein, we present a new category of dual-targeting PROTAC degraders designed to specifically target ERα and ARO. Among them, compound 18c bifunctionally degrades and inhibits ERα/ARO, thus effectively suppressing the proliferation of MCF-7 cells while showing negligible cytotoxicity to normal cells. In vivo, 18c promotes the degradation of ERα and ARO and inhibits the growth of MCF-7 xenograft tumors. Finally, compound 18c demonstrates promising antiproliferative and ERα degradation activity against the ERαMUT cells. These findings suggest that 18c, being the inaugural dual-targeting degrader for ERα and ARO, warrants further advancement for the management of BC and the surmounting of endocrine resistance.

Abstract PO1-24-06: Prolactin Hormone-Induced Mammary Differentiation and Anti-tumorigenic Role in Breast Cancer

Abstract The premise of differentiation therapy in cancer is a strategy that aims at engaging-forward differentiation and cellular reprograming restricting the proliferative, tumor repopulation, stemness, EMT and metastatic capacities of tumor cells leading to the cessation of the aggressive tumor phenotype and offering the cancer patients improved survival for decades. Therefore, deciphering molecular mechanisms deriving differentiation in normal mammary and breast cancer cells may allow the discovery of innovative differentiation-based biomarkers and therapeutics in breast cancer. Lactation is an intricate process that results in the ability of the breast cells to produce a complex nutritious biological fluid to nurse the new-born. While the beneficial effects of breastfeeding to the infant is irrefutable, its effects on maternal health are less investigated especially in relation to breast cancer that still affects 1 in 8 women in high income countries and 1 in 20 globally. Importantly, epidemiological studies have linked breastfeeding to reduced risk of breast cancer by promoting terminal differentiation of the breast epithelial cells. While breastfeeding process is regulated by multiple hormones, growth factors, and transcriptional regulators, the lactation hormone prolactin (PRL) is known to be directly implicated in the hormonal control of breastfeeding. Extensive research including our own work has shown that PRL/PRL receptor (PRLR) pathway derives mammary gland development and importantly mammary epithelial cell terminal differentiation allowing successful lactation. In contrast the role of PRL in breast cancer is still to be fully defined. Importantly, we have accumulated compelling evidence using in-silico publicly available patient data sets and molecular data implicating this pathway as a clinically relevant pro-differentiation pathway driving differentiation and cellular reprograming suppressing stemness, EMT, metastasis and tumorigenesis in breast cancer. To better characterize PRL signaling mediating its pro-differentiation effects, we used large-scale unbiased proteomics analysis of PRLR/interacting proteins in breast cancer cells. Our analyses revealed several novel PRLR-interactors. We have further confirmed these interactions through co-immunoprecipitations/western blotting analyses in breast cancer cells representative the different breast cancer subtypes. We also examined their functional contributions to mammary differentiation and tumorigenesis using in vitro and in vivo assays. Moreover, we defined their potential clinical relevance using bioinformatics in silico databases of breast cancer. Together our study delineates novel PRL/PRLR-downstream signaling mediators important for mammary differentiation and tumorigenesis and may thus be useful as biomarkers and/or therapeutic targets in breast cancer. Citation Format: Dana Hamam, Suhad Ali. Prolactin Hormone-Induced Mammary Differentiation and Anti-tumorigenic Role in Breast Cancer [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 PO1-24-06.

GATA3 functions downstream of BRCA1 to promote DNA damage repair and suppress dedifferentiation in breast cancer

BackgroundInadequate DNA damage repair promotes aberrant differentiation of mammary epithelial cells. Mammary luminal cell fate is mainly determined by a few transcription factors including GATA3. We previously reported that GATA3 functions downstream of BRCA1 to suppress aberrant differentiation in breast cancer. How GATA3 impacts DNA damage repair preventing aberrant cell differentiation in breast cancer remains elusive. We previously demonstrated that loss of p18, a cell cycle inhibitor, in mice induces luminal-type mammary tumors, whereas depletion of either Brca1 or Gata3 in p18 null mice leads to basal-like breast cancers (BLBCs) with activation of epithelial-mesenchymal transition (EMT). We took advantage of these mutant mice to examine the role of Gata3 as well as the interaction of Gata3 and Brca1 in DNA damage repair in mammary tumorigenesis.ResultsDepletion of Gata3, like that of Brca1, promoted DNA damage accumulation in breast cancer cells in vitro and in basal-like breast cancers in vivo. Reconstitution of Gata3 improved DNA damage repair in Brca1-deficient mammary tumorigenesis. Overexpression of GATA3 promoted homologous recombination (HR)-mediated DNA damage repair and restored HR efficiency of BRCA1-deficient cells. Depletion of Gata3 sensitized tumor cells to PARP inhibitor (PARPi), and reconstitution of Gata3 enhanced resistance of Brca1-deficient tumor cells to PARP inhibitor.ConclusionsThese results demonstrate that Gata3 functions downstream of BRCA1 to promote DNA damage repair and suppress dedifferentiation in mammary tumorigenesis and progression. Our findings suggest that PARP inhibitors are effective for the treatment of GATA3-deficient BLBCs.

The androgen receptor interacts with GATA3 to transcriptionally regulate a luminal epithelial cell phenotype in breast cancer

BackgroundThe androgen receptor (AR) is a tumor suppressor in estrogen receptor (ER) positive breast cancer, a role sustained in some ER negative breast cancers. Key factors dictating AR genomic activity in a breast context are largely unknown. Herein, we employ an unbiased chromatin immunoprecipitation-based proteomic technique to identify endogenous AR interacting co-regulatory proteins in ER positive and negative models of breast cancer to gain new insight into mechanisms of AR signaling in this disease.ResultsThe DNA-binding factor GATA3 is identified and validated as a novel AR interacting protein in breast cancer cells irrespective of ER status. AR activation by the natural ligand 5α-dihydrotestosterone (DHT) increases nuclear AR-GATA3 interactions, resulting in AR-dependent enrichment of GATA3 chromatin binding at a sub-set of genomic loci. Silencing GATA3 reduces but does not prevent AR DNA binding and transactivation of genes associated with AR/GATA3 co-occupied loci, indicating a co-regulatory role for GATA3 in AR signaling. DHT-induced AR/GATA3 binding coincides with upregulation of luminal differentiation genes, including EHF and KDM4B, established master regulators of a breast epithelial cell lineage. These findings are validated in a patient-derived xenograft model of breast cancer. Interaction between AR and GATA3 is also associated with AR-mediated growth inhibition in ER positive and ER negative breast cancer.ConclusionsAR and GATA3 interact to transcriptionally regulate luminal epithelial cell differentiation in breast cancer regardless of ER status. This interaction facilitates the tumor suppressor function of AR and mechanistically explains why AR expression is associated with less proliferative, more differentiated breast tumors and better overall survival in breast cancer.

Discovery of imidazopyridine-pyrazoline-hybrid structure as SHP-1 agonist that suppresses phospho-STAT3 signaling in human breast cancer cells

Signal transducer and activator of transcription 3 (STAT3) promotes breast cancer malignancy and controls key processes including proliferation, differentiation, and survival in breast cancer cells. Although many methods for treating breast cancer have been improved, there is still a need to discover and develop new methods for breast cancer treatment. Therefore, we synthesized a new compound 2-(4-(2,3-dichlorophenyl)piperazin-1-yl)-1-(3-(2,6-dimethylimidazo[1,2-a]pyridin-3-yl)-5-(3-nitrophenyl)-4,5-dihydro-1H-pyrazol-1-yl)ethanone (DIP). We aimed to evaluate the anti-cancer effect of DIP in breast cancer cells and clarify its mode of action. We noted that DIP abrogated STAT3 activation and STAT3 upstream kinases janus-activated kinase (JAK) and Src kinases. In addition, DIP promoted the levels of SHP-1 protein and acts as SHP-1 agonist. Further, silencing of SHP-1 gene reversed the DIP-induced attenuation of STAT3 activation and apoptosis. DIP also induced apoptosis through modulating PARP cleavage and oncogenic proteins. Moreover, DIP also significantly enhanced the apoptotic effects of docetaxel through the suppression of STAT3 activation in breast cancer cells.Overall, our data indicated that DIP may act as a suppressor of STAT3 cascade, and it could be a new therapeutic strategy in breast cancer cells.

NOTCH Pathway Genes in Ovarian Cancer: Clinical Significance and Associations with Immune Cell Infiltration.

Activation of the NOTCH signaling pathway is associated with tumorigenesis. The aim of this study was to investigate NOTCH pathway gene functions and regulatory mechanisms in ovarian cancer (OC). We conducted a bioinformatics analysis of publicly available datasets in order to identify potential NOTCH-related mechanisms, associated genes, biological pathways, and their relation to immune function. Significant differential expression of the NOTCH pathway genes DLL1, DLL3, DLL4, HES1, HEY1, JAG1, NOTCH2, NOTCH3, and NOTCH4 was observed between OC samples and normal controls. Low expression of DLL4 and of NOTCH4 in OC patients was associated with International Federation of Gynecology and Obstetrics (FIGO) stage (p <0.001 and p = 0.036, respectively), while high expression of NOTCH3 was associated with race (p = 0.039) and age (p = 0.044). JAG2 and NOTCH1 expression were significantly associated with progression-free interval (PFI) (p = 0.011 and p = 0.039, respectively). DLL1 (Hazard Ratio (HR): 2.096; 95% CI: 1.522-2.886, p < 0.001) and NOTCH1 (HR: 0.711; 95% CI: 0.514-0.983, p = 0.039) expression were independently associated with PFI in multivariate analysis. DLL1, DLL3, JAG1, JAG2, NOTCH3 and NOTCH4 expression could significantly differentiate OC from non-cancer samples. Genes associated with the NOTCH pathway were mainly enriched in five signaling pathways: the NOTCH signaling pathway, breast cancer, endocrine resistance, Th1 and Th2 cell differentiation, and oxidative phosphorylation. The expression of NOTCH pathway genes was significantly associated with immune cell infiltration. NOTCH pathway genes appear to play an important role in the progression of OC by regulating immune cells, endocrine resistance, Th1 and Th2 cell differentiation, and oxidative phosphorylation. JAG2 and NOTCH1 are potential biomarkers and therapeutic targets for the treatment of OC.

Estrogen Receptor Signaling in Breast Cancer.

Estrogen receptor (ER) signaling is a critical regulator of cell proliferation, differentiation, and survival in breast cancer (BC) and other hormone-sensitive cancers. In this review, we explore the mechanism of ER-dependent downstream signaling in BC and the role of estrogens as growth factors necessary for cancer invasion and dissemination. The significance of the clinical implications of ER signaling in BC, including the potential of endocrine therapies that target estrogens' synthesis and ER-dependent signal transmission, such as aromatase inhibitors or selective estrogen receptor modulators, is discussed. As a consequence, the challenges associated with the resistance to these therapies resulting from acquired ER mutations and potential strategies to overcome them are the critical point for the new treatment strategies' development.

Rutaecarpine induces the differentiation of triple-negative breast cancer cells through inhibiting fumarate hydratase.

Triple-negative breast cancer (TNBC) is one of the most aggressive human cancers and has poor prognosis. Approximately 80% of TNBC cases belong to the molecular basal-like subtype, which can be exploited therapeutically by inducing differentiation. However, the strategies for inducing the differentiation of TNBC remain underexplored. A three-dimensional (3D) morphological screening model based on a natural compound library was used to identify possible candidate compounds that can induce TNBC cell differentiation. The efficacy of rutaecarpine was verified using assays: RT-qPCR, RNA-seq, flow cytometry, immunofluorescence, SCENITH and label-free LC-MS/MS. The direct targets of rutaecarpine were identified through drug affinity responsive target stability (DARTS) assay. A xenograft mice model was also constructed to confirm the effect of rutaecarpine in vivo. We identified that rutaecarpine, an indolopyridoquinazolinone, induces luminal differentiation of basal TNBC cells in both 3D spheroids and in vivo mice models. Mechanistically, rutaecarpine treatment leads to global metabolic stress and elevated ROS in 3D cultured TNBC cells. Moreover, NAC, a scavenger of ROS, impedes rutaecarpine-induced differentiation of TNBC cells in 3D culture. Finally, we identified fumarate hydratase (FH) as the direct interacting target of rutaecarpine. The inhibition of FH and the knockdown of FH consistently induced the differentiation of TNBC cells in 3D culture. Our results provide a platform for differentiation therapy drug discovery using 3D culture models and identify rutaecarpine as a potential compound for TNBC treatment.

MiR-203 drives breast cancer cell differentiation

A hallmark of many malignant tumors is dedifferentiated (immature) cells bearing slight or no resemblance to the normal cells from which the cancer originated. Tumor dedifferentiated cells exhibit a higher capacity to survive to chemo and radiotherapies and have the ability to incite tumor relapse. Inducing cancer cell differentiation would abolish their self-renewal and invasive capacity and could be combined with the current standard of care, especially in poorly differentiated and aggressive tumors (with worst prognosis). However, differentiation therapy is still in its early stages and the intrinsic complexity of solid tumor heterogeneity demands innovative approaches in order to be efficiently translated into the clinic. We demonstrate here that microRNA 203, a potent driver of differentiation in pluripotent stem cells (ESCs and iPSCs), promotes the differentiation of mammary gland tumor cells. Combining mouse in vivo approaches and both mouse and human-derived tridimensional organoid cultures, we report that miR-203 influences the self-renewal capacity, plasticity and differentiation potential of breast cancer cells and prevents tumor cell growth in vivo. Our work sheds light on differentiation-based antitumor therapies and offers miR-203 as a promising tool for directly confronting the tumor-maintaining and regeneration capability of cancer cells.

Cut-off Analysis of HLA-A and HLA-B/C Expression as a Potential Prognosticator of Favorable Survival in Patients With Metastatic Breast Cancer.

Loss of differentiation of breast cancer cells in association with a down-regulated class I human leukocyte antigen (HLA) expression can lead to proliferation unhampered by cytotoxic T lymphocytes, which has been proven to be of prognostic relevance. The objective of this study was to determine the levels of HLA-A and HLA-B/C expression in metastatic breast cancer (MBC) cells and their usefulness for predicting 5-year survival. This prospective double-blinded cohort study analyzed patients starting a new line of therapy for MBC. RT-qPCR was used to determine the levels of HLA-A and B/C expression in MBC cells and the mRNA-based tumor intrinsic subtype. Two receiver operating characteristic curves (ROC) were constructed in order to determine whether HLA-A and HLA-B/C expression levels can be used for predicting 5-year survival. Youden J points, and sensitivity and specificity optimized cut-off points were determined for both ROC curves. We enrolled 34 patients. The ROC curve for HLA-B/C had the highest AUC compared to HLA-A (0.55 vs. 0.42). High levels of HLA-A and HLA-B/C expression (40-ΔΔCT of 33.5 and 31.9, respectively) were highly specific (reaching 87.5% for HLA-A and even 100% specificity for HLA-B/C) yet insensitive for five-year survival in our study. High expression of certain class I HLA molecule subtypes by MBCs, in particular high HLA-A or B/C expression by MBC cells seems very specific in predicting the 5-year survival. We determined cut-off values for these HLA molecule clusters with high specificity, which might help identify patients with a favorable prognosis as prognosticators of a 5-year overall survival if their sensitivity is improved in larger prospective cohorts.

Comparative docking analysis of tyrosine kinase inhibitors with HER2 and HER4 receptors.

Tyrosine kinase receptors promote the growth and differentiation of normal breast and malignant human breast cancer cells, known as ERBB receptors. Various ERBB receptors are EGFR/ErbB1 and ErbB2/neu, which get over expressed in different solid tumors that activate upon binding of ligand to the extra cellular domain of these receptors. Of note, the epidermal growth factor receptor (EGFR) is a prime contributor to cancer through the involvement of four receptor tyrosine kinases (RTKs), namely, HER1, HER2, HER3, and HER4. Among them, HER2 and HER4 are majorly associated with breast cancer. Non-peptide quinazoline compounds homologous of the adenosine triphosphate (ATP) are competitively inhibited to RTKs to prevent cancer growth and metastasis. Various small drug molecule that targets the RTKs having the same scaffold, includes Lapatinib, Tivozanib, Erlotinib, Gefitinib, Crizotinib, and Ceritinib. The present study aims to investigate the comparative potential of structurally similar TKIs against HER2 and HER4 receptor receptors-silico molecular docking using FlexX software (LeadIT 2.3.2). Each docked complex's interaction profile was performed using BIOVIA Discovery Studio Visualizer 4.0. Molecular docking analysis was performed in order to get deeper insights into the interaction and binding pattern of the ligands with HER2 and HER4 receptors. The docking results revealed the Lapatinib compound acquired the relatively highest binding score of -32.36 kcal/mol and -35.76 kcal/mol with HER2 and HER4 proteins, respectively, concerning other compounds. Lapatinib is identified as a potential inhibitor for both the RTKs. Our study thus suggests the probable direction that could be further explored in inhibiting EGFR protein harboring breast cancer.

ADRB3 induces mobilization and inhibits differentiation of both breast cancer cells and myeloid-derived suppressor cells

Metastatic tumors are mainly composed of neoplastic cells escaping from the primary tumor and inflammatory cells egressing from bone marrow. Cancer cell and inflammatory cell are remained in the state of immaturity during migration to distant organs. Here, we show that ADRB3 is crucial in cell mobilization and differentiation. Immunohistochemistry revealed ADRB3 expression is significantly more frequent in breast cancer tissues than in adjacent noncancerous tissues (92.1% vs. 31.5%). Expression of ADRB3 correlated with malignant degree, TNM stage and poor prognosis. Moreover, ADRB3 expression was markedly high in activated disseminated tumor cells, myeloid-derived suppressor cells (MDSCs), lymphocytes and neutrophil extracellular traps of patients. Importantly, ADRB3 promoted the expansion of MDSC through stimulation of bone marrow mobilization and inhibiting of the differentiation of immature myeloid cells. Furthermore, ADRB3 promoted MCF-7 cells proliferation and inhibited transdifferentiation into adipocyte-like cell by activating mTOR pathway. Ultimately, the MDSC-deficient phenotype of ADRB3 -/- PyMT mice was associated with impairment of mammary tumorigenesis and reduction in pulmonary metastasis. Collectively, ADRB3 promotes metastasis by inducing mobilization and inhibiting differentiation of both breast cancer cells and MDSCs.

Non-homogeneous dispersion of graphene in polyacrylonitrile substrates induces a migrastatic response and epithelial-like differentiation in MCF7 breast cancer cells

BackgroundRecent advances from studies of graphene and graphene-based derivatives have highlighted the great potential of these nanomaterials as migrastatic agents with the ability to modulate tumor microenvironments. Nevertheless, the administration of graphene nanomaterials in suspensions in vivo is controversial. As an alternative approach, herein, we report the immobilization of high concentrations of graphene nanoplatelets in polyacrylonitrile film substrates (named PAN/G10) and evaluate their potential use as migrastatic agents on cancer cells.ResultsBreast cancer MCF7 cells cultured on PAN/G10 substrates presented features resembling mesenchymal-to-epithelial transition, e.g., (i) inhibition of migratory activity; (ii) activation of the expression of E-cadherin, cytokeratin 18, ZO-1 and EpCAM, four key molecular markers of epithelial differentiation; (iii) formation of adherens junctions with clustering and adhesion of cancer cells in aggregates or islets, and (iv) reorganization of the actin cytoskeleton resulting in a polygonal cell shape. Remarkably, assessment with Raman spectroscopy revealed that the above-mentioned events were produced when MCF7 cells were preferentially located on top of graphene-rich regions of the PAN/G10 substrates.ConclusionsThe present data demonstrate the capacity of these composite substrates to induce an epithelial-like differentiation in MCF7 breast cancer cells, resulting in a migrastatic effect without any chemical agent-mediated signaling. Future works will aim to thoroughly evaluate the mechanisms of how PAN/G10 substrates trigger these responses in cancer cells and their potential use as antimetastatics for the treatment of solid cancers.Graphical

Understanding the Role of Estrogen Receptor Status in PRODH/POX-Dependent Apoptosis/Survival in Breast Cancer Cells.

Simple SummaryThe estrogen receptor (ER) status and the availability of agonists or antagonists of these receptors determine the processes of growth, differentiation, and proliferation of breast cancer cells. Estrogens and anti-estrogenic compounds have been shown to influence breast cancer cell survival/apoptosis via action through the mitochondrial enzyme proline dehydrogenase/proline oxidase (PRODH/POX). In this review, we highlight the molecular effects of ER stimulation/inhibition in signaling pathways.It has been suggested that activation of estrogen receptor α (ER α) stimulates cell proliferation. In contrast, estrogen receptor β (ER β) has anti-proliferative and pro-apoptotic activity. Although the role of estrogens in estrogen receptor-positive breast cancer progression has been well established, the mechanism of their effect on apoptosis is not fully understood. It has been considered that ER status of breast cancer cells and estrogen availability might determine proline dehydrogenase/proline oxidase (PRODH/POX)-dependent apoptosis. PRODH/POX is a mitochondrial enzyme that converts proline into pyrroline-5-carboxylate (P5C). During this process, ATP (adenosine triphosphate) or ROS (reactive oxygen species) are produced, facilitating cell survival or death, respectively. However, the critical factor in driving PRODH/POX-dependent functions is proline availability. The amount of this amino acid is regulated at the level of prolidase (proline releasing enzyme), collagen biosynthesis (proline utilizing process), and glutamine, glutamate, α-ketoglutarate, and ornithine metabolism. Estrogens were found to upregulate prolidase activity and collagen biosynthesis. It seems that in estrogen receptor-positive breast cancer cells, prolidase supports proline for collagen biosynthesis, limiting its availability for PRODH/POX-dependent apoptosis. Moreover, lack of free proline (known to upregulate the transcriptional activity of hypoxia-inducible factor 1, HIF-1) contributes to downregulation of HIF-1-dependent pro-survival activity. The complex regulatory mechanism also involves PRODH/POX expression and activity. It is induced transcriptionally by p53 and post-transcriptionally by AMPK (AMP-activated protein kinase), which is regulated by ERs. The review also discusses the role of interconversion of proline/glutamate/ornithine in supporting proline to PRODH/POX-dependent functions. The data suggest that PRODH/POX-induced apoptosis is dependent on ER status in breast cancer cells.

A DOCK1 Gene-Derived Circular RNA Is Highly Expressed in Luminal Mammary Tumours and Is Involved in the Epithelial Differentiation, Growth, and Motility of Breast Cancer Cells.

Simple SummaryIn the present study, we define the expression of 15 selected circular RNAs, using a panel of 18 breast cancer cell lines recapitulating the heterogeneity of tumors and consisting of three distinct groups according to the mesenchymal/epithelial phenotype. We identify circDOCK1-1 generated from the DOCK1 gene as an important regulator of the epithelial differentiation of mammary tumour cells. In addition, our high-throughput transcriptomic studies provide information on the genes that are regulated by circDOCK1-1, casting new light on the gene networks involved in the processes underlying the development of mammary tumours. Our results further indicate that circDOCK1-1 controls cell–cell adhesion and consequently random as well as directional motility. Besides their interest from a basic point of view, the data generated may be of translational relevance, as they suggest that strategies aimed at increasing the amounts or at stimulating the activity of circDOCK1-1 may be of significance for the treatment of a subset of triple-negative breast cancer patients.Circular RNAs are regulatory molecules involved in numerous cellular processes and may be involved in tumour growth and diffusion. Here, we define the expression of 15 selected circular RNAs, which may control the process of epithelial-to-mesenchymal transition, using a panel of 18 breast cancer cell lines recapitulating the heterogeneity of these tumours and consisting of three groups according to the mesenchymal/epithelial phenotype. A circular RNA from the DOCK1 gene (hsa_circ_0020397) shows low/undetectable levels in triple-negative mesenchymal cell lines, while its content is high in epithelial cell lines, independent of estrogen receptor or HER2 positivity. RNA-sequencing experiments performed on the triple-negative/mesenchymal MDA-MB-231 and MDA-MB-157 cell lines engineered to overexpress hsa_circ_0020397 demonstrate that the circRNA influences the expression of 110 common genes. Pathway analysis of these genes indicates that overexpression of the circular RNA differentiates the two mesenchymal cell lines along the epithelial pathway and increases cell-to-cell adhesion. This is accompanied by growth inhibition and a reduction in the random/directional motility of the cell lines. The upregulated AGR2, ENPP1, and PPP1R9A genes as well as the downregulated APOE, AQP3, CD99L2, and IGFBP4 genes show an opposite regulation by hsa_circ_0020397 silencing in luminal CAMA1 cells. The results provide novel insights into the role played by specific circular RNAs in the generation/progression of breast cancer.

16P Repurposing rosiglitazone with chemotherapy in breast cancer: A sequence-specific synergy?

Recent years have witnessed a trend to search for the possibility of repurposing widely prescribed drugs in the field of oncology. This applies to thiazolidinediones, peroxisome proliferator-activated receptor-gamma (PPARγ) receptor agonists, the anti-diabetic drugs which showed antitumor activities and evidence for the induction of breast cancer cells differentiation. We aimed to investigate the potential of repurposing a PPARγ ligand, rosiglitazone (RGZ), in combination with either of two chemotherapeutic agents, doxorubicin (Dox) or cisplatin (Cis) for the in vitro treatment of breast cancer cell line, MCF-7.

Adipose-derived stem/stromal cell secretome modulates breast cancer cell proliferation and differentiation state towards aggressiveness

It is becoming increasingly evident that mesenchymal stem/stromal cells are recruited by cancer cells from nearby endogenous host stroma and promote events such as tumor proliferation, angiogenesis, invasion, and metastasis, as well as mediate therapeutic resistance. Consequently, understanding the regulatory mechanisms of ASCs that influence the tumor microenvironment may provide an avenue for further treatment. To understand the role of the ASC secretome in breast cancer cell proliferation, death, and phenotype alteration, adipose-derived stem cell-conditioned medium (mASC) was used to cultivate MCF-7 and MDA-MB-231 cells. These breast cancer cells in mASC showed a shorter doubling time, higher frequency of EdU positivity, and higher levels of phosphorylated histone 3. In addition, increased expression of cyclin B1 was observed, suggesting that proliferation was induced. The mASC was also able to increase apoptosis in MCF-7 cells, which was confirmed by caspase-7 activation. The number of tumor-initiating cells (CD44+ CD24-/low) and migration capacity were increased in cells cultivated in mASC. These data collectively suggest that ASC-conditioned medium can induce selective pressure by increasing cell proliferation, giving rise to a more aggressive phenotype in MCF-7 and MDA-MB-231 cells. Our study provides a foundation for further elucidation of the precise mechanism underlying ASCs in breast cancer cells and the modulation of ASCs in potential therapeutic uses.

Nanowire Assisted Mechanotyping of Cellular Metastatic Potential

Nanotechnology has provided tools for next generation biomedical devices which rely on nanostructure interfaces with living cells. In vitro biomimetic structures have enabled observation of cell response to various mechanical and chemical cues, and there is a growing interest in isolating and harnessing the specific cues that three-dimensional microenvironments can provide without the requirement for such culture and the experimental drawbacks associated with it. Here we report a randomly oriented gold coated Si nanowire substrate with patterned hydrophobic-hydrophilic areas for differentiation of isogenic breast cancer cells of varying metastatic potential. When considering synthetic surfaces for the study of cell-nanotopography interfaces, randomly oriented nanowires more closely resemble the isotropic architecture of natural extracellular matrix as compared to currently more widely used vertical nanowire arrays. In the study reported here, we show that primary cancer cells preferably attach to the hydrophilic region of randomly oriented nanowire substrate while secondary cancer cells do not adhere. Using machine learning analysis of fluorescence images, cells were found to spread and elongate on the nanowire substrates as compared to a flat substrate, where they mostly remain round, when neither surface was coated with extracellular matrix (ECM) proteins. Such platforms can not only be used for developing bioassays but also as stepping stones for tissue printing technologies where cells can be selectively patterned at desired locations.

Upregulation of miR-206 is a potential diagnostic biomarker in breast cancer

Breast cancer is one of the most common malignancies, and like most cancers, most cases are caused by somatic mutations. Due to estrogen's role in the growth, differentiation, and division of breast and endometrial cancer cells, tamoxifen is used as an estrogen receptor antagonist in breast cancer cells with estrogen receptor (ER +) has a special place, which unfortunately in one-third of the Cases are resisted. This study aimed to investigate the effect of tamoxifen-treated tumor-derived exosomes on the expression pattern of Twist and Bcl-2 oncogenic genes in fibroblast cells. MCF-7 breast cancer cell line and fibroblast cells were purchased and cultured in a complete culture medium. After the appropriate number of cells was reached, they were treated with the appropriate concentration of tamoxifen. Cellular supernatant was then gathered in flasks, and exosomes were extracted from them. After extracting RNA from exosomes and cDNA synthesis, the expression level of miR-206, Twist-1, and Bcl-2 genes were evaluated using the Real-Time PCR method. The electronic microscope results confirmed the correctness of the exosomes isolated from the tumor cell culture medium. It has also been shown that tamoxifen treatment increases the expression of miR-206 in exosomes derived from breast tumor cells. The control group which has been kept untreated induced the expression level of Twist-1 and Bcl-2 genes time-dependently. However, when tamoxifen-treated tumor-derived exosomes treated the target cells, the expression level of oncogenic miRs Twist-1 and Bcl-2 were declined over time. Overall, this study showed that tamoxifen treatment on breast cancer cells could apply its antioncogenic effects on tumor stromal cells, such as fibroblasts, by altering the expression levels of exosomal microRNAs in tumor cells.

Human Chorionic Gonadotropin-Mediated Induction of Breast Cancer Cell Proliferation and Differentiation.

Human chorionic gonadotropin (hCG) is a hormone that specifically binds to luteinizing hormone receptor (LHR) and exerts several roles, including the support of pregnancy and fetal gonadal steroidogenesis. Since hCG is also expressed by some tumor types, like breast cancer, many efforts have been made to study its role in neoplesia, with some studies showing a cancer-supportive role and others showing a cancer-protective role. A critical examination of the literature highlighted that the in vitro effect of hCG has been tested in the presence of fetal serum, which contains other gonadotropins, in the culture medium. Thus, we hypothesized that the use of serum in the cell culture medium might influence the cell response to the hCG treatment due to the presence of other hormones. Thus, we analyzed the in vitro effect of highly purified hCG on cell proliferation and the activation of the down-stream signal transduction pathway in three breast cancer cell lines, particularly focusing on MCF7, cultured in serum-deprived conditions. Our data show that hCG increases cell proliferation and activates the down-stream target Akt, together with a decrease of the LHR mRNA expression level. Finally, we also tested the differentiation capacity of hCG on MCF7 cancer stem cells (CSCs) and show that it favors the proliferation and differentiation of these cells, thus suggesting that hCG also renders cells more able to colonize and invade the organs.