Transformation Of Breast Epithelial Cells Research Articles

FKBP10-inhibited β-catenin ubiquitination in the malignant transformation of breast epithelial cells.

e12580 Background: Current model of breast cancer (BCa) progression suggests a linear and three-stage process from normal epithelial tissue to ductal carcinoma in situ (DCIS), and then invasive ductal carcinoma (IDC). Since the detailed mechanisms for BCa oncogenesis remain largely unclear and there is still a lack of root-cause level interventions, exploring the underlying molecular alterations during three-stage process of BCa carcinogenesis is urgently needed. Methods: Three-stage specimens from the very same patients were collected. High-throughput sequencing was applied to obtain the differentially expressed genes among normal, DCIS, and IDC samples. Expression level and prognostic value of the selected gene were evaluated by PCR, western blot, tissue chip, and bioinformatics analysis. MCF10DCIS and MCF10Ca cell lines were respectively used to establish DCIS and IDC tumor models in breast epithelial cell-specific gene knockout mice. Patient-matched DCIS and IDC organoids were also constructed. Signaling pathways associated with malignant transformation of breast epithelial cells were detected by using high-throughput sequencing in mouse models and organoids. Protein binding was evaluated by protein mass spectrometry and co-immunoprecipitation. Results: By using high-throughput sequencing, we found that FKBP10 levels were gradually increased in three-stage specimens from the very same patients and were associated with poor prognosis. By establishing DCIS and IDC models in FKBP10flox/floxCre+/- and FKBP10flox/floxCre-/- control mice, we confirmed that FKBP10 deficiency could suppress BCa formation. Besides, FKBP10 knockdown could reduce oncogenic potentials in patient-matched DCIS and IDC organoids. Wnt/β-catenin signaling pathway was related to malignant transformation of breast epithelial cells, when MCF10DCIS+FKBP10flox/floxCre+/- model, MCF10Ca+FKBP10flox/floxCre+/- model, FKBP10-knockdown DCIS and IDC organoids, and their corresponding controls were comprehensively compared. Moreover, FKBP10 was found to inhibit β-catenin ubiquitination with the help of deubiquitinase Trim13, thus activating Wnt/β-catenin signaling pathway and accelerating malignant transformation of breast epithelial cells. Increased level of β-catenin was able to promote FKBP10 expression in a feedback loop. We also confirmed that exosome-loaded FKBP10-targeting peptide could suppress tumor growth both in vitro and in vivo. Conclusions: FKBP10-inhibited β-catenin ubiquitination was responsible in the malignant transformation from normal tissue to DCIS, and then IDC. Our study would uncover novel regulatory mechanisms of FKBP10 in three-stage process of BCa carcinogenesis and provide a new therapeutic approach for clinical treatment.

Oscillatory Hypoxia Can Induce Senescence of Adipose-Derived Mesenchymal Stromal Cells Potentiating Invasive Transformation of Breast Epithelial Cells.

Obesity is strongly associated with occurrence, metastasis, and resistance to therapy in breast cancers, which also exhibit high adipose content in the tumor microenvironment. Adipose tissue-derived mesenchymal stromal cells (ASCs) are recruited to breast cancer by many mechanisms, including hypoxia, and contribute to metastatic transition of the cancer. Breast cancers are characterized by regions of hypoxia, which can be temporally unstable owing to a mismatch between oxygen supply and consumption. Using a high-sensitivity nanopatterned stromal invasion assay, we found that ASCs could promote stromal invasion of not only breast cancer cell lines but also MCF10A1, a cell line derived from untransformed breast epithelium. RNA sequencing of MCF10A1 cells conditioned with medium from ASCs revealed upregulation of genes associated with increased cell migration, chemotaxis, and metastasis. Furthermore, we found that fluctuating or oscillating hypoxia could induce senescence in ASCs, which could result in an increased invasive potential in the treated MCF10A1 cells. These findings highlight the complex interplay within the breast cancer microenvironment, hypoxia, and the role of ASCs in transforming even non-cancerous breast epithelium toward an invasive phenotype, providing insights into early metastatic events.

HOXA5-Mediated Stabilization of IκBα Inhibits the NF-κB Pathway and Suppresses Malignant Transformation of Breast Epithelial Cells.

Loss of HOXA5 reduces IκBα stability and increases NF-κB signaling to exacerbate breast cancer aggressiveness, providing new insights into the tumor suppressor functions of HOXA5.

Contribution of adrenergic mechanisms for the stress-induced breast cancer carcinogenesis.

Breast cancer is the most common and deadliest type of cancer in women. Stress exposure has been associated with carcinogenesis and the stress released neurotransmitters, noradrenaline and adrenaline, and their cognate receptors, can participate in the carcinogenesis process, either by regulating tumor microenvironment or by promoting systemic changes. This work intends to provide an overview of the research done in this area and try to unravel the role of adrenergic ligands in the context of breast carcinogenesis. In the initiation phase, adrenergic signaling may favor neoplastic transformation of breast epithelial cells whereas, during cancer progression, may favor the metastatic potential of breast cancer cells. Additionally, adrenergic signaling can alter the function and activity of other cells present in the tumor microenvironment towards a protumor phenotype, namely macrophages, fibroblasts, and by altering adipocyte's function. Adrenergic signaling also promotes angiogenesis and lymphangiogenesis and, systemically, may induce the formation of preneoplastic niches, cancer-associated cachexia and alterations in the immune system which contribute for the loss of quality of life of breast cancer patients and their capacity to fight cancer. Most studies points to a major contribution of β2 -adrenoceptor activated pathways on these effects. The current knowledge of the mechanistic pathways activated by β2 -adrenoceptors in physiology and pathophysiology, the availability of selective drugs approved for clinical use and a deeper knowledge of the basic cellular and molecular pathways by which adrenergic stimulation may influence cancer initiation and progression, opens the possibility to use new therapeutic alternatives to improve efficacy of breast cancer treatments.

Oncogenic and Tumor Suppressive Components of the Cell Cycle in Breast Cancer Progression and Prognosis.

Cancer, a disease of inappropriate cell proliferation, is strongly interconnected with the cell cycle. All cancers consist of an abnormal accumulation of neoplastic cells, which are propagated toward uncontrolled cell division and proliferation in response to mitogenic signals. Mitogenic stimuli include genetic and epigenetic changes in cell cycle regulatory genes and other genes which regulate the cell cycle. This suggests that multiple, distinct pathways of genetic alterations lead to cancer development. Products of both oncogenes (including cyclin-dependent kinase (CDKs) and cyclins) and tumor suppressor genes (including cyclin-dependent kinase inhibitors) regulate cell cycle machinery and promote or suppress cell cycle progression, respectively. The identification of cyclins and CDKs help to explain and understand the molecular mechanisms of cell cycle machinery. During breast cancer tumorigenesis, cyclins A, B, C, D1, and E; cyclin-dependent kinase (CDKs); and CDK-inhibitor proteins p16, p21, p27, and p53 are known to play significant roles in cell cycle control and are tightly regulated in normal breast epithelial cells. Following mitogenic stimuli, these components are deregulated, which promotes neoplastic transformation of breast epithelial cells. Multiple studies implicate the roles of both types of components—oncogenic CDKs and cyclins, along with tumor-suppressing cyclin-dependent inhibitors—in breast cancer initiation and progression. Numerous clinical studies have confirmed that there is a prognostic significance for screening for these described components, regarding patient outcomes and their responses to therapy. The aim of this review article is to summarize the roles of oncogenic and tumor-suppressive components of the cell cycle in breast cancer progression and prognosis.

Obese Adipose Tissue as a Driver of Breast Cancer Growth and Development: Update and Emerging Evidence.

Obesity is an established risk factor for breast cancer growth and progression. A number of advances have been made in recent years revealing new insights into this link. Early events in breast cancer development involve the neoplastic transformation of breast epithelial cells to cancer cells. In obesity, breast adipose tissue undergoes significant hormonal and inflammatory changes that create a mitogenic microenvironment. Many factors that are produced in obesity have also been shown to promote tumorigenesis. Given that breast epithelial cells are surrounded by adipose tissue, the crosstalk between the adipose compartment and breast epithelial cells is hypothesized to be a significant player in the initiation and progression of breast cancer in individuals with excess adiposity. The present review examines this crosstalk with a focus on obese breast adipose-derived estrogen, inflammatory mediators and adipokines, and how they are mechanistically linked to breast cancer risk and growth through stimulation of oxidative stress, DNA damage, and pro-oncogenic transcriptional programs. Pharmacological and lifestyle strategies targeting these factors and their downstream effects are evaluated for feasibility and efficacy in decreasing the risk of obesity-induced breast epithelial cell transformation and consequently, breast cancer development.

Lysine oxidase exposes a dependency on the thioredoxin antioxidant pathway in triple-negative breast cancer cells.

Transformed cells are vulnerable to depletion of certain amino acids. Lysine oxidase (LO) catalyzes the oxidative deamination of lysine, resulting in lysine depletion and hydrogen peroxide production. Although LO has broad antitumor activity in preclinical models, the cytotoxic mechanisms of LO are poorly understood. Triple (ER/PR/HER2)-negative breast cancer (TNBC) cells were treated with control media, lysine-free media or control media supplemented with LO and examined for cell viability, caspase activation, induction of reactive oxygen species (ROS) and antioxidant signaling. To determine the role of nuclear factor erythroid 2-related factor 2 (NRF2) and thioredoxin reductase-1 (TXNRD1) in LO-induced cell death, NRF2 and TXNRD1 were individually silenced by RNAi. Additionally, the pan-TXNRD inhibitor auranofin was used in combination with LO. LO activates caspase-independent cell death that is suppressed by necroptosis and ferroptosis inhibitors, which are inactive against lysine depletion, pointing to fundamental differences between LO and lysine depletion. LO rapidly induces ROS with a return to baseline levels within 24h that coincides temporally with induction of TXNRD activity, the rate-limiting enzyme in the thioredoxin antioxidant pathway. ROS induction is required for LO-mediated cell death and NRF2-dependent induction of TXNRD1. Silencing NRF2 or TXNRD1 enhances the cytotoxicity of LO. The pan-TXNRD inhibitor auranofin is synergistic with LO against transformed breast epithelial cells, but not untransformed cells, underscoring the tumor-selectivity of this strategy. LO exposes a redox vulnerability of TNBC cells to TXNRD inhibition by rendering tumor cells dependent on the thioredoxin antioxidant pathway for survival.

G protein-coupled kisspeptin receptor induces metabolic reprograming and tumorigenesis in estrogen receptor-negative breast cancer

Triple-negative breast cancer (TNBC) is a highly metastatic and deadly disease. TNBC tumors lack estrogen receptor (ERα), progesterone receptor (PR), and HER2 (ErbB2) and exhibit increased glutamine metabolism, a requirement for tumor growth. The G protein-coupled kisspeptin receptor (KISS1R) is highly expressed in patient TNBC tumors and promotes malignant transformation of breast epithelial cells. This study found that TNBC patients displayed elevated plasma kisspeptin levels compared with healthy subjects. It also provides the first evidence that in addition to promoting tumor growth and metastasis in vivo, KISS1R-induced glutamine dependence of tumors. In addition, tracer-based metabolomics analyses revealed that KISS1R promoted glutaminolysis and nucleotide biosynthesis by increasing c-Myc and glutaminase levels, key regulators of glutamine metabolism. Overall, this study establishes KISS1R as a novel regulator of TNBC metabolism and metastasis, suggesting that targeting KISS1R could have therapeutic potential in the treatment of TNBC.

MicroRNA-181a suppresses progestin-promoted oncogenic transformation of breast epithelial cells through interfering PGRMC1 signalling pathway

MicroRNA-181a suppresses progestin-promoted oncogenic transformation of breast epithelial cells through interfering PGRMC1 signalling pathway

Preclinical Breast Cancer Models to Investigate Metabolic Priming by Methionine Restriction.

We have developed a novel therapeutic paradigm ("metabolic priming") for cancer whereby restriction of the essential amino acid methionine activates a number of cell-stress-response pathways that can be selectively targeted to enhance the therapeutic impact of methionine restriction. One example of metabolic priming is the combination of methionine restriction with proapoptotic TRAIL receptor-2 (TRAIL-R2) agonists. Methionine restriction enhances the cell surface expression of TRAIL-R2 selectively in transformed breast epithelial cells and renders them more susceptible to cell death induction by TRAIL-R2 agonists in cellular and murine models of breast cancer. This methods review focuses on preclinical models of breast cancer to investigate metabolic priming by methionine restriction. Multiple cell-based methods are detailed to measure cell viability, cell survival, caspase activity, apoptosis, and matrix detachment-induced cell death (anoikis). In addition, we describe an orthotopic model of metastatic breast cancer that utilizes mCherry-fluorescently-labeled human breast cancer cells. This model captures the entire metastatic cascade from the mammary gland to the lung and mimics key features of the human disease. These breast-cancer models can be readily adapted to other tumor types. Overall, we provide a stepwise, translationally-relevant approach to study metabolic priming in the context of cancer.

Long-term exposure to extremely low-dose of nicotine and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) induce non-malignant breast epithelial cell transformation through activation of the a9-nicotinic acetylcholine receptor-mediated signaling pathway.

Breast cancer (BC) is the most common cancer affecting women worldwide and has been associated with active tobacco smoking. Low levels of nicotine (Nic) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), have been detected in cases of second-hand smoke (SHS). However, the correlation between SHS and BC risk remains controversial. In this study, we investigated whether the physiological SHS achievable dose of Nic and tobacco specific nitrosamine, NNK act together to induce breast carcinogenesis using an in vitro breast cell carcinogenesis model. Immortalized non-tumorigenic breast epithelial cell line, HBL-100 used for a time-course assay, was exposed to very low levels of either Nic or NNK, or both. The time-course assay consisted of 23 cycles of nitrosamines treatment. In each cycle, HBL-100 cells were exposed to 1pM of Nic and/or 100 femtM of NNK for 48 hours. Cells were passaged every 3 days and harvested after 10, 15, and 23 cycles. Our results demonstrated that the tumorigenicity of HBL-100, defined by soft agar colony forming, proliferation, migration and invasion abilities, was enhanced by co-exposure to physiologically SHS achievable doses of Nic and NNK. In addition, α9-nAChR signaling activation, which plays an important role in cellular proliferation and cell survival, was also observed. Importantly, an increase in stemness properties including the prevalence of CD44+/CD24- cells, increase Nanog expression and mammosphere-forming ability were also observed. Our results indicate that chronic and long term exposure to environmental tobacco smoke, may induce breast cell carcinogenesis even at extremely low doses.

Curcumin interacts directly with the Cysteine 259 residue of STAT3 and induces apoptosis in H-Ras transformed human mammary epithelial cells

Signal transducer and activator of transcription 3 (STAT3) is a transcription factor that is latent but constitutively activated in many types of cancers. It is well known that STAT3 plays a key role in inflammation-associated tumorigenesis. Curcumin is an anti-inflammatory natural compound isolated from the turmeric (Curcuma longa L., Zingiberaceae) that has been extensively used in a traditional medicine over the centuries. In the present study, we have found that curcumin inhibits STAT3 signaling that is persistently overactivated in H-Ras transformed breast epithelial cells (H-Ras MCF10A). Specific cysteine residues present in STAT3 appear to be critical for the activity as well as conformation of this transcription factor. We identified the cysteine residue 259 of STAT3 as a putative site for curcumin binding. Site-directed mutation of this cysteine residue abolished curcumin-induced inactivation of STAT3 and apoptosis in H-Ras MCF10A cells. The α,β-unsaturated carbonyl moiety of curcumin appears to be essential in its binding to STAT3 in H-Ras MCF10A cells. Tetrahydrocurcumin that lacks such electrophilic moiety failed to interact with STAT3 and to induce apoptosis in the same cell line. Taken together, our findings suggest that curcumin can abrogate aberrant activation of STAT3 through direct interaction, thereby inhibiting STAT3-mediated mammary carcinogenesis.

Histone deacetylase inhibitor trichostatin A and autophagy inhibitor chloroquine synergistically exert anti-tumor activity in H-ras transformed breast epithelial cells.

Histone deacetylase inhibitors (HDACIs) cause oncogene-transformed mammalian cell death. Our previous study indicated that HDACIs activate forkhead box O1 (FOXO1) and induce autophagy in liver and colon cancer cells. However, whether FOXO1 is involved in HDACI-mediated oncogene-transformed mammalian cell death remains unclear. In the present study, H-ras transformed MCF10A cells were used to investigate the role of FOXO1 in this pathway. Results showed that trichostatin A (TSA), a HDACI, activated apoptosis in MCF10A-ras cells, but not in MCF10A cells. Furthermore, TSA activated FOXO1 via P21 upregulation, whereas the knockdown of FOXO1 reduced TSA-induced cell death. In addition, TSA induced autophagy in MCF10A and MCF10A-ras cells by blocking the mammailian target of rapamycin signaling pathway. Furthermore, autophagy inhibition lead to higher MCF10A-ras cell death by TSA, thus indicating that autophagy is essential in cell survival. Taken together, the present study demonstrated that TSA causes oncogene-transformed cell apoptosis via activation of FOXO1 and HDACI-mediated autophagy induction, which served as important cell survival mechanisms. Notably, the present findings imply that a combination of HDACIs and autophagy inhibitors produce a synergistic anticancer effect.

First person – Libi Anandi

ABSTRACT First Person is a series of interviews with the first authors of a selection of papers published in Journal of Cell Science, helping early-career researchers promote themselves alongside their papers. Libi Anandi is the first author on ‘DNA-dependent protein kinase plays a central role in transformation of breast epithelial cells following alkylation damage’, published in Journal of Cell Science. Libi is a PhD student in the laboratory of Mayurika Lahiri at Indian Institute of Science Education and Research, Pune, India, investigating the early events of cellular transformation.

Abstract 5286: Type 2 diabetes and increased risk of estrogen receptor-negative breast cancer in African American women

Abstract Introduction: Type 2 diabetes (T2D) is hypothesized to be a risk factor for breast cancer. Possible mechanisms include adverse effects of impaired glucose regulation on endogenous hormone levels and increased inflammation of adipose tissue, which may be favorable to breast epithelial cell transformation, tumor-related angiogenesis, and cancer cell invasion. Recent meta-analyses suggest that T2D may be associated with a 15-20% increase in risk, but whether that increase is due to residual confounding by body mass index (BMI) is uncertain. Further, few studies have reported results separately by estrogen receptor (ER) status of the tumor, none have had appreciable numbers of ER- cases, and the only previous report on the association in African American (AA) women analyzed all subtypes together. Methods: We used data from the prospective Black Women’s Health Study to examine the relation of T2D to incidence of invasive breast cancer, overall and by ER subtype, among 54,337 AA women free from T2D and breast cancer at baseline and followed for 20 years. Included were 1,851 incident breast cancer cases, with 468 classified as ER- and 914 as ER+; data on ER status were not available for 469 cases. Participants were asked about medical conditions on each biennial questionnaire. In a validation study, 95% of self-reports of diabetes were confirmed by medical records. Cox proportional hazards regression was used to compute incidence rate ratios (IRR) for breast cancer for women with T2D relative to women without T2D, controlling for age, family history of breast cancer, BMI at age 18, waist-hip ratio, years of education, and reproductive factors. Results: The multivariable IRR for T2D versus no diabetes was 1.20 (95% confidence interval 1.01-1.41) for all breast cancer, 1.42 (1.02-1.98) for ER- breast cancer, and 1.06 (0.83-1.36) for ER+ breast cancer. Most cases had had diabetes for at least five years before the breast cancer diagnosis. IRRs for ≥5 years duration of diabetes were 1.46 (1.02-2.07) for ER- and 1.08 (0.83-1.41) for ER+ breast cancer. Recent BMI was not associated with increased risk of either ER subtype and was not a confounder in the present analyses. BMI at age 18, which was inversely associated with breast cancer risk in this and other studies, was the only appreciable confounder; in multivariable models that did not control for BMI at age 18, IRRs were 1.37 (0.99-1.90) and 1.03 (0.81-1.33) for ER- and ER+ breast cancer, respectively. Conclusions: The findings suggest that AA women with T2D are at increased risk of ER- breast cancer. AA women are about two times as likely to be diagnosed with ER- breast cancer as are U.S. white women and also have a markedly higher prevalence of T2D. Their higher prevalence of diabetes may contribute to the disparity in incidence of ER- breast cancer. The next step will be to assess whether risk of ER- breast cancer among diabetic women differs according to how well the diabetes is controlled. Citation Format: Julie R. Palmer, Nelsy Castro-Webb, Kimberly A. Bertrand, Traci N. Bethea, Lynn Rosenberg. Type 2 diabetes and increased risk of estrogen receptor-negative breast cancer in African American women [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5286. doi:10.1158/1538-7445.AM2017-5286

High IL-1R8 expression in breast tumors promotes tumor growth and contributes to impaired antitumor immunity.

Tumors develop numerous strategies to fine-tune inflammation and avoid detection and eradication by the immune system. The identification of mechanisms leading to local immune dysregulation is critical to improve cancer therapy. We here demonstrate that Interleukin-1 receptor 8 (IL-1R8 - previously known as SIGIRR/TIR8), a negative regulator of Toll-Like and Interleukin-1 Receptor family signaling, is up-regulated during breast epithelial cell transformation and in primary breast tumors. IL-1R8 expression in transformed breast epithelial cells reduced IL-1-dependent NF-κB activation and production of pro-inflammatory cytokines, inhibited NK cell activation and favored M2-like macrophage polarization. In a murine breast cancer model (MMTV-neu), IL-1R8-deficiency reduced tumor growth and metastasis and was associated with increased mobilization and activation of immune cells, such as NK cells and CD8+ T cells. Finally, immune-gene signature analysis in clinical specimens revealed that high IL-1R8 expression is associated with impaired innate immune sensing and T-cell exclusion from the tumor microenvironment. Our results indicate that high IL-1R8 expression acts as a novel immunomodulatory mechanism leading to dysregulated immunity with important implications for breast cancer immunotherapy.

Metformin sensitizes triple-negative breast cancer to proapoptotic TRAIL receptor agonists by suppressing XIAP expression.

Despite robust antitumor activity in diverse preclinical models, TNF-related apoptosis-inducing ligand (TRAIL) receptor agonists have not demonstrated efficacy in clinical trials, underscoring the need to identify agents that enhance their activity. We postulated that the metabolic stress induced by the diabetes drug metformin would sensitize breast cancer cells to TRAIL receptor agonists. Human triple (estrogen receptor, progesterone receptor, and HER2)-negative breast cancer (TNBC) cell lines were treated with TRAIL receptor agonists (monoclonal antibodies or TRAIL peptide), metformin, or the combination. The effects on cell survival, caspase activation, and expression of TRAIL receptors and the antiapoptotic protein XIAP were determined. In addition, XIAP was silenced by RNAi in TNBC cells and the effects on sensitivity to TRAIL were determined. The antitumor effects of metformin, TRAIL, or the combination were evaluated in an orthotopic model of metastatic TNBC. Metformin sensitized diverse TNBC cells to TRAIL receptor agonists. Metformin selectively enhanced the sensitivity of transformed breast epithelial cells to TRAIL receptor agonist-induced caspase activation and apoptosis with little effect on untransformed breast epithelial cells. These effects of metformin were accompanied by robust reductions in the protein levels of XIAP, a negative regulator of TRAIL-induced apoptosis. Silencing XIAP in TNBC cells mimicked the TRAIL-sensitizing effects of metformin. Metformin also enhanced the antitumor effects of TRAIL in a metastatic murine TNBC model. Our findings indicate that metformin enhances the activity of TRAIL receptor agonists, thereby supporting the rationale for additional translational studies combining these agents.

Baicalein has protective effects on the 17β-estradiol-induced transformation of breast epithelial cells.

Epidemiologic and systematic studies have indicated that flavonoid consumption is associated with a lower incidence of breast cancer. Baicalein is the primary flavonoid derived from the roots of Scutellaria baicalensis Georgi. In the current study, the long-term exposure of breast epithelial cells to 17β-estradiol (E2) was used to investigate the chemopreventive potential of baicalein on neoplastic transformation. The results demonstrated that baicalein significantly inhibited E2-induced cell growth, motility, and invasiveness, and suppressed E2-induced misshapen acini formation in 3D cultures. Furthermore, it inhibited the ability of E2-induced cells to form clones in agarose and tumors in NOD/SCID immunodeficient mice. Docking studies using Sybyl-X 1.2 software showed that baicalein could bind to both estrogen receptor-α (ERa) and G-protein coupled estrogen receptor 30 (GPR30), which are two critical E2-mediated pathways. Baicalein prevented the E2-induced ERa-mediated activation of nuclear transcriptional signaling by interfering with the trafficking of ERa into the nucleus and subsequent binding to estrogen response elements, thereby decreasing the mRNA levels of ERa target genes. It also inhibited E2-induced GPR30-mediated signal transduction, as well as the transcription of GPR30-regulated genes. Therefore, these results suggest that baicalein is a potential drug for reducing the risk of estrogen-dependent breast cancer.

DNA-dependent protein kinase plays a central role in transformation of breast epithelial cells following alkylation damage.

DNA alkylating agents form the first line of cancer chemotherapy. They not only kill cells but also behave as potential carcinogens. MNU, a DNA methylating agent, is well known to induce mammary tumours in rodents. However, the mechanism of tumorigenesis is not well understood. Our study reports a novel role played by DNA-dependent protein kinase (DNA-PK) in methylation damage-induced transformation using three-dimensional breast acinar cultures. Here, we report that exposure of breast epithelial cells to MNU inhibited polarisation at the basolateral domain, increased dispersal of the Golgi at the apical domain and induced an epithelial-to-mesenchymal transition (EMT)-like phenotype as well as invasion. This altered Golgi phenotype correlated with impaired intracellular trafficking. Inhibition of DNA-PK resulted in almost complete reversal of the altered Golgi phenotype and partial rescue of the polarity defect and EMT-like phenotype. The results confirm that methylation damage-induced activation of DNA-PK is a major mechanism in mediating cellular transformation.This article has an associated First Person interview with the first author of the paper.

Platelet activating factor leads to initiation and promotion of breast cancer

Bioactive molecules present in the tumor milieu are known to contribute substantially to tumor progression. Phospholipid mediators are a group of molecules that have roles in normal physiology as well as in pathological conditions. Platelet activating factor (PAF), a phospholipd mediator, secreted by cells present in tumor microenvironment has been implicated to have a possible role in cancer progression. Here, we highlight our study of the potential role of PAF in inducing transformation of breast epithelial cells grown as three dimensional cultures. We have also attempted to dissect the motility related molecular pathway activated upon PAF stimulation in MDA-MB 231 cells. This study further calls for detailed analysis of pathways downstream of PAF signalling which would aid in identification of targets and designing of treatment strategies.