Breast Epithelial Cell Line MCF-10A Research Articles

Fluorescence-based discrimination of breast cancer cells by direct exposure to 5-aminolevulinic acid.

Protoporphyrin IX‐fluorescence measurement is a powerful in situ approach for cancer detection after oral/topical administration of 5‐aminolevulinic acid. However, this approach has not been clinically established for breast cancer, probably due to insufficient delivery of 5‐aminolevulinic acid to the mammary glands. In the present study, we directly exposed breast cancer cells to 5‐aminolevulinic acid to assess their discrimination via protoporphyrin IX‐fluorescence. Fluorescence intensity (FI) was measured in the human breast cancer cell lines MCF7 and MDA‐MB‐231 and breast epithelial cell line MCF10A by confocal microscopy and flow cytometry. After 5‐aminolevulinic acid exposure for 2 hours, protoporphyrin IX‐FI in MCF7 and MDA‐MB‐231 cells significantly increased with marked cell‐to‐cell variability, whereas that in MCF10A cells increased moderately. Combined exposure of the cancer cells to 5‐aminolevulinic acid and Ko143, a specific inhibitor of ATP‐binding cassette transporter G2, further increased protoporphyrin IX‐FI and alleviated the cell‐to‐cell variability in MCF7 and MDA‐MB‐231 cells, indicating improvement in the reproducibility and accuracy for fluorescence‐based cancer detection. The increased FI by combined administration of these two drugs was also demonstrated in cells obtained via fine needle aspiration from mouse xenograft models inoculated with MDA‐MB‐231 cells. Furthermore, a cutoff value for increased protoporphyrin IX‐FI ratio, before and after exposure to these drugs, clearly discriminated between cancer and noncancer cells. Taken together, direct exposure to 5‐aminolevulinic acid and Ko143 may be a promising strategy for efficient fluorescence‐based detection of breast cancer cells ex vivo using fine needle aspiration.

Abstract 4605: Exosomes harvested from patient-derived-explants or cells-enhance proliferation and migration in TNBC breast cancer cells and breast epithelial cells

Abstract Triple negative breast cancer (TNBC) is a clinically aggressive breast cancer subtype due in part by high rates of metastasis and poor prognoses. TNBC tumors are molecularly heterogeneous and lack targetable receptors common in other breast cancer subtypes (estrogen receptor, HER2/Neu amplification), hindering the discovery of effective targeted therapies. Our group has designed a series of experiments to gain insight into the role of the tumor microenvironment in TNBC proliferation, migration and invasion. Patient-derived xenografts (PDXs) are translational models that are necessary to use in the laboratory setting when studying the complex tumor microenvironment of TNBC tumors. Recent breast cancer-focused studies show exosomes can be local and systemic cell-to-cell transporters of oncogenic information. Here, we aim to better understand how tumor-derived exosomes harvested from TNBC PDX models affect cell proliferation and migration when cultured with either triple negative breast cancer cell line MDA-MB-231 or non-tumorigenic breast epithelial cell line MCF-10A. PDX tumors or cells were plated in 2D culture conditions, and exosomes were isolated and purified from the cell culture media. Proliferation and migration assays were then performed after co-culture of the exosomes (or RPMI-1640 media as a negative control) with breast cell lines (MDA-MB-231, MCF-10A). The Alamar blue dye exclusion assay was used to measure proliferation, and absorbance was measured to quantify relative proliferation amongst the different treatment groups. To evaluate cell migration, a transwell migration assay was utilized where the breast cancer cell lines were plated with either the exosomal media or standard growth media as the chemoattractant for 48 hours. For invasion experiments, the transwell migration assay was employed. Our data indicate that TNBC PDX-derived exosomes increased cell proliferation in the MDA-MB-231 cell line by an average of approximately 60% compared to the control (p ≤ 0.05). We observed similar patterns of increased cell proliferation in the MCF-10A cell line, with an increase of 34% when cells were exposed to exosomes (p ≤ 0.05) compared to the control. Exosomes from TNBC PDX models increased migration in MDA-MB-231 cells by 4% and in MCF-10A cells by 10 percent. Interestingly, when we screened the exosomes from different TNBC PDX models, we found that one invasive TNBC PDX model contributed to the increased proliferation and migration in both the MDA-MB-231 and MCF-10A cell lines. Exosomes harvested and purified from TNBC patient-derived explants, and 2D culture conditions models increased proliferation and migration, cell line MDA-MB-231, and the non-tumorigenic breast epithelial cell line MCF-10A. Our data suggests that exosomes are key mediators in the progression of cancer. Note: This abstract was not presented at the meeting. Citation Format: Jordon Coward, Margarite D. Matossian, Paige A. Roberts, Jasmine Johnson, Matthew E. Burow, KiTani P. Lemieux. Exosomes harvested from patient-derived-explants or cells-enhance proliferation and migration in TNBC breast cancer cells and breast epithelial cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4605.

Abstract 4602: Abi1 promotes breast cancer progression by regulating cell-matrix adhesion

Abstract Breast cancer is one of the most common diagnosed cancers in the United States. There will be approximately 266,120 new breast cancer cases in the U.S. and over 40,000 patients are predicted to die from the malignant progression of their breast cancer tumors in 2018. Traditional therapeutic methods of the invasive breast cancer include surgery accompanied by chemotherapy. However, following the initial therapy patients often relapse and eventually die from tumor metastasis. Abl interactor 1, or Abi1, is an adaptor protein which regulates actin polymerization through participation in WAVE (Wiscott-Aldrich syndrome protein family verprolin homologous) complex. The WAVE regulatory complex (also called WRC), regulates actin based cellular behavior, such as cellular adhesion and cell migration, by activating Arp2/3 complex and promoting actin polymerization. Previous studies indicated the direct interaction between integrin α4 and Abi1, which suggests a potential role of Abi1 in regulating cell-matrix adhesion signaling by involved in the inside-out integrin signaling pathways. In order to test the above hypothesis, we developed two genetic engineered Abi1 knocked-out breast cell lines from either HER2+ breast cancer cell line SKBR3 or normal breast epithelial cell line MCF10A by using CRISPR-Cas9 technique. After confirming inactivation of Abi1 gene by Western blotting, DNA and RNA sequencing, cells were harvested and analyzed for integrins levels. Western blotting results indicated dysregulation of multiple integrins in the Abi1 knock-out cell lines. The results from subsequent immunofluorescence experiments of the Abi1 knock-out cell lines also suggested changes in cell-matrix adhesion signaling using staining for scaffold protein paxillin and phosphorylated Focal-Adhesion-Kinase (FAK) as readouts. Our findings suggest that Abi1 might functions as a key regulator in breast cancer tumor progression by playing an important role in regulating signal pathways in cell-matrix adhesion. Supported by the Carol Baldwin Foundation of CNY, and in part by NIH-NCI grant No. R01 CA161018. Citation Format: Xiang Li, Angelina Regua, Gennady Bratslavsky, Vladimir A. Kuznetsov, Leszek Kotula. Abi1 promotes breast cancer progression by regulating cell-matrix adhesion [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4602.

Abstract 1073: Role of CD44 in the transition of ductal carcinoma in situ to invasive breast carcinoma

Abstract Ductal carcinoma in situ (DCIS) transition to invasive tumor is an important issue for breast cancer. The human MCF10DCIS.com cell line (abbreviated as MCF10DCIS) is derived from the human MCF10A breast epithelial cell line. The MCF10DCIS xenografts are similar to human high grade comedo DCIS. In the xenograft assay, MCF10DCIS cells form DCIS-like lesion, remain as DCIS-like lesion in the first few weeks, and then progress into invasive carcinoma. Thus, it is an excellent model to study human breast cancer transition from DCIS to invasive carcinoma. To the best of our knowledge, it is also the only cell model for DCIS transition to invasive carcinoma. We investigated the role of CD44 in breast cancer transition from DCIS to invasive carcinoma by knockdown the expression of CD44 in the MCF10DCIS xenograft model. Our results show that knockdown of CD44 expression in the MCF10DCIS cells enhances DCIS transition to invasive carcinoma. Accordingly, a previous study has shown that CD44 expression is lower in invasive human breast tumors compared with DCIS, especially in luminal A subtype. We have also observed that CD44 expression is lower in the invasive carcinomas compared with DCIS. Furthermore, we provide evidence that CD44 plays a role in maintaining the integrity of the myoepithelial layer. Our study uncovered an unexpected role of CD44 in the prevention of DCIS transition to invasive carcinoma. Our findings have important implications for breast cancer. Note: This abstract was not presented at the meeting. Citation Format: Fang Liu, Jun Zhou, Tanima Kundu-Roy, Joseph Wahler, Jae Young So, Yong Lin, You-Rong Lou, Nicola J. Barnard, Isao Matsuura, Nanjoo Suh. Role of CD44 in the transition of ductal carcinoma in situ to invasive breast carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1073.

Anti-tumor properties of methoxylated analogues of resveratrol in malignant MCF-7 but not in non-tumorigenic MCF-10A mammary epithelial cell lines

Resveratrol is a plant-derived polyphenol that is known for its anti-inflammatory and anti-tumorigenic properties in in vitro and in vivo models. Recent studies show that some resveratrol analogues might be more potent anti-tumor agents, which may partly be attributed to their ability to activate the aryl hydrocarbon receptor (AHR). Here, the anti-tumorigenic properties of resveratrol and structural analogues oxyresveratrol, pinostilbene, pterostilbene and tetramethoxystilbene (TMS) were studied in vitro, using in the malignant human MCF-7 breast cancer cell line and non-tumorigenic breast epithelial cell line MCF-10A.Cell viability and migration assays showed that methoxylated analogues of resveratrol are more potent anti-tumorigenic compounds than resveratrol and its hydroxylated analogue oxyresveratrol, with 2,3’,4,5’-tetramethoxy-trans-stilbene (TMS) being the most potent compound. TMS decreased MCF-7 tumor cell viability with 50% at 3.6 μM and inhibited migration with 37.5 ± 14.8% at 3 μM. In addition, TMS activated the AHR more potently (EC50 in a reporter gene assay 2.0 μM) and induced AHR-mediated induction of cytochrome P450 1A1 (CYP1A1) activity (EC50 value of 0.7 μM) more than resveratrol and the other analogues tested. Cell cycle analysis showed that TMS induced a shift in cell cycle status from the G1 to the G2/M phase causing a cell cycle arrest in the MCF-7 cells, while no effect of TMS was observed in the non-tumorigenic MCF-10A mammary epithelial cell line. Gene expression analysis showed that 3 μM TMS increased gene expression of CYP1A1 (289-fold), CYP1B1 (5-fold) and Nqo1 (2-fold), and decreased gene expression of IL-8 (3-fold) in MCF-7 cells. In MCF-10A cells, 10 μM TMS also increased gene expression of CYP1A1 (5-fold) and CYP1B1 (2-fold), but decreased gene expression of Nqo1 (1.4-fold) in contrast to MCF-7 cells.TMS displays more potent anti-tumorigenic properties and activates the AHR more effectively than resveratrol. In addition, this is the first study to show that TMS, but not resveratrol, selectively inhibits the cell cycle of breast tumor cells and not the non-tumorigenic cells. Our study provides more insight in the anti-tumor properties of the methoxylated analogues of resveratrol in breast cells in vitro.

The use of 3D cultures of MCF-10A and MCF-12A cells by high content screening for effect-based analysis of non-genotoxic carcinogens

The human breast epithelial cell lines MCF-10A and MCF-12A form well-differentiated acinus-like structures when grown in three-dimensional matrigel culture over a period of 20 days. In the present study, both cell lines were tested for their suitability to serve as an effect-based in vitro test system for non-genotoxic carcinogens. A software solution for automated Acinus Detection And Morphological Evaluation (ADAME) was developed to automatically acquire acinus images and to determine morphological parameters such as acinus size, lumen size, and acinus roundness. A number of test compounds were tested for their capacity to affect acinus formation and cellular differentiation. Human epidermal growth factor stimulated acinus growth for both cell lines whereas all-trans retinoic acid inhibited acinus growth. The strong estrogen 17β-estradiol had no effect on acinus formation of estrogen receptor (ER)-negative MCF-10A cells, but yielded larger MCF-12A (ER-positive) acini. Thus, the parallel use of both cell lines allows the identification of estrogenic properties of a given test compound.

Effects of Notch signalling on the expression of SEMA3C, HMGA2, CXCL14, CXCR7, and CCL20 in breast cancer.

Metastasis is the main reason for death in breast cancer. Understanding the molecular players in metastasis is crucial for diagnostic and therapeutic purposes. Notch signalling plays an oncogenic role in breast tumorigenesis and is involved in metastasis. Downstream mediators of Notch signalling in prometastatic processes are not yet fully discovered. Here we aimed to investigate whether Notch signalling regulates the expression of SEMA3C, HMGA2, CXCL14, CXCR7, and CCL20, which are involved in prometastatic processes, in breast cell lines. To this end, expression of the selected genes was analysed following Notch activation by overexpression of the Notch1 intracellular domain in the normal breast epithelial cell line MCF10A, and inhibition by silencing of the Notch transcriptional mediator RBPjκ in the breast cancer cell line MDA MB 231. SEMA3C and HMGA2 mRNA were decreased, while CXCL14 and CXCR7 mRNA were increased significantly in response to Notch activation in MCF10A cells. Notch inhibition in MDA MB 231 cells significantly decreased HMGA2 and CCL20 mRNA. Protein levels were not significantly altered by Notch modulation. In conclusion, we showed that Notch signalling regulates expression of SEMA3C, CXCL14, CCL20, CXCR7, and HMGA2, which are prominent candidate genes that might function downstream of Notch to induce prometastatic processes.

MiRNA-192-5p impacts the sensitivity of breast cancer cells to doxorubicin via targeting peptidylprolyl isomerase A.

The administration of doxorubicin (DOX) is one of the first-line treatments of breast cancer. However, acquisition of resistance remains the major obstacle restricting the clinical application of DOX. MicroRNAs (miRNAs) are small, noncoding RNAs which play crucial role in epigenetic regulation. Recent studies have shown that miRNAs are associated with tumor chemoresistance. Here we aim to explore the role of miRNA-192-5p in resistance to DOX in breast cancer cells. Normal human breast epithelial cell line MCF-10A, breast cancer cell line Michigan Cancer Foundation-7 (MCF-7), and DOX-resistant breast cancer cell line MCF-7/ADR were used here. The expression of miR-192-5p was examined by qPCR, and the expression of peptidylprolyl isomerase A (PPIA) was examined by qPCR and Western blot. The effects of miR-192-5p overexpression on the sensitivity to DOX were confirmed by Methylthiazolyldiphenyl-tetrazolium bromide (MTT) and Annexin-V/PI assay. Downstream molecular mechanisms, including PPIA, BAD, CASP9, Bcl-2, and c-Jun N-terminal kinase (JNK) activation, were detected by Western blot and qPCR. Luciferase reporter assay was used to validate the association between miR-192-5p and PPIA. miR-192-5p was downregulated while PPIA was upregulated in MCF-7/ADR cells. Functionally, miR-192-5p overexpression increased sensitivity to DOX by promoting cell apoptosis. Mechanistically, miR-192-5p overexpression performed its function by activating JNK, augmenting BAD and caspase9 expression, and suppressing Bcl-2 and PPIA expression. Luciferase assay validated that PPIA was a direct target of miR-192-5p. miR-192-5p sensitizes breast cancer cells to DOX by targeting PPIA, suggesting that miR-192-5p might serve as a novel target for reversing DOX resistance and controlling breast tumor growth.

MicroRNA-498 promotes proliferation and migration by targeting the tumor suppressor PTEN in breast cancer cells.

Triple negative breast cancer (TNBC) is a subtype of breast cancer with a poor prognosis and high mortality rate. The tumor suppressor phosphatase and tensin homolog deleted on chromosome 10 (PTEN) plays an important role in cell proliferation and cell migration by negatively regulating the PI3K/Akt pathway. PTEN is downregulated by microRNAs in multiple cancers. However, few microRNAs have been reported to directly target PTEN in TNBC. In this study, microRNAs predicted to target PTEN were screened by immunoblotting and luciferase reporter assays. Expression levels of microRNA-498 (miR-498) were measured by TaqMan microRNA assays. We performed clonogenic, cell cycle and scratch wound assays to examine the oncogenic role of miR-498. We demonstrated that miR-498 directly targeted the 3'untranslated region of PTEN mRNA and reduced PTEN protein levels in TNBC cells. Compared with the non-tumorigenic breast epithelial cell line MCF-10A, TNBC cell lines overexpressed miR-498. Moreover, miR-498 promoted cell proliferation and cell cycle progression in TNBC cells in a PTEN-dependent manner. Suppressing miR-498 overexpression impaired the oncogenic effects of miR-498 on cell proliferation and cell migration. This study identified a novel microRNA (miR-498) overexpressed in TNBC cells and its oncogenic role in suppressing PTEN. These results provide new insight into the downregulation of PTEN and indicate a potential therapeutic target for treating TNBC.

Abstract 4993: Breast epithelial cell lines from normal breast with luminal and intrinsic subtypes -enriched gene expression document inter-individual differences in differentiation cascade

Abstract Breast cancers are classified into five intrinsic subtypes based on gene expression profile. It is suggested that these intrinsic subtypes originate from specific developmental stage of breast epithelial cell hierarchy, stem-progenitor-mature cell. However, normal breast epithelial cell lines representing these intrinsic subtypes are yet to be created. Using normal breast tissues of ancestry-mapped Caucasian, African American, and Hispanic women and a primary cell culturing system that allows growth of normal epithelial cells of different developmental stages including estrogen receptor-positive mature luminal cells, we created 15 human telomerase-immortalized breast epithelial cell lines. These cells formed acini on a matrigel and ductal structures on 3-dimensional collagen or hydrogel, indicating that these cell lines have retained characteristics of normal breast epithelial cells. RNA sequencing and PAM50 intrinsic subtype clustering algorithms were used to identify the intrinsic subtypes of the immortalized cell lines together with two well characterized “normal” breast epithelial cell lines MCF10A and HMEC as well as luminal breast cancer cell line MCF-7. Unlike MCF10A and HMEC, which are enriched for basal-like gene expression pattern, our cell lines classified into luminal A, basal, and normal-like subtypes. This was also reflected in the immunofluorescence staining with basal marker KRT14 and luminal marker KRT19. Few of these cell lines were dual positive for KRT14 and KRT19, but in varying proportions. Cell lines representing claudin-low subtypes were also created, which are phenotypically (CD201+/EpCAM-) different from the above cell lines. Cell lines showed inter-individual differences in stemness/differentiation capabilities and variable basal activity of signaling molecules such as NF-kB, AP-1 and pERK, which is consistent with, possibly reflecting, recent discoveries of genetic variations in gene regulatory regions among general population that contribute to widespread differences in gene expression/signaling under “normal” state. As majority of breast cancers are believed to originate from luminal progenitor cells, which are well represented our cell lines, these cell lines are ideal to delineate the impact of inter-individual and ethnic differences in normal breast biology on breast cancer initiation and progression as well as to determine whether cell-type-origin instead of genomic aberration drives intrinsic subtype-enriched gene expression patterns in breast tumors. Citation Format: Brijesh Kumar, Mayuri Prasad, Manjushree Anjanappa, Poornima Nakshatri, Natascia Marino, Anna Maria Storniolo, Xi Rao, Sheng Liu, Jun Wan, Yunlong Liu, Harikrishna Nakshatri. Breast epithelial cell lines from normal breast with luminal and intrinsic subtypes -enriched gene expression document inter-individual differences in differentiation cascade [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4993.

Abstract 840: ATR inhibition is a promising radiosensitizing strategy for chemotherapy-resistant triple negative breast cancer (TNBC)

Abstract Purpose: TNBC represents an aggressive subtype characterized by earlier relapse and worse survival compared to non-TNBC. Patients with residual TNBC after neoadjuvant chemotherapy (NAC) have a high risk of locoregional recurrence despite aggressive subsequent local therapies, including RT. Thus, new radiosensitizers that address chemoresistant TNBC (i.e residual disease after NAC) are needed. ATR plays a key role in the cellular response to replication stress and DNA damage. TNBC is characterized by G1 checkpoint loss, homologous recombination deficiency (HRD), and other features which increase dependence on ATR pathway signaling. We hypothesized that VX-970, a selective inhibitor of ATR, would effectively radiosensitize TNBC. Methods: Cell lines representing varying subtypes of TNBC (MDA-MB-231, HCC1806, and BT-549) and the normal breast epithelial cell line MCF10a were investigated in clonogenic survival, cell cycle, and DNA damage signaling and repair assays. In addition, Mayo Clinic (MC)TNBC1 and MCTNBC2, patient derived xenograft models (PDXs) generated prospectively from baseline and chemoresistant residual disease surgical specimens after NAC, respectively, of unique patients in the Breast Cancer Genome Guided Therapy Study were analyzed. Tumors were injected into hind-legs of athymic nude mice and animals were randomized to: 1) Vehicle 2) RT 3) VX-970 4) RT + VX-970. RT was delivered in 5 daily fractions of 2 Gy. VX-970 was administered daily 1 hour prior to RT at a dose of 60 mg/kg. Exome sequencing was assessed for germ-line and/or somatic alterations in HR genes and an ex-vivo RAD51 foci formation assay was applied to confirm the functional status of HR in each PDX model. Results: In vitro, VX-970 preferentially inhibited ATR-Chk1-CDC25a signaling, abrogated the RT-induced G2/M checkpoint, delayed resolution of γH2AX and 53BP1 foci and reduced colony formation after RT in MDA-MB-231, HCC1806, and BT-549 relative to MCF10a. In vivo, VX-970 did not exhibit single agent activity at the dose administered but markedly sensitized both MCTNBC1 and MCTNBC2 to RT, suggesting that VX-970 could overcome chemoresistant TNBC biology. For MCTNBC1 and MCTNBC2, the median time to tumor tripling was 26 vs 49 days (p=0.002) and 25 vs 43 days (p=0.006) for the RT and RT + VX-970 groups, respectively. Ex-vivo RAD51 foci formation was robust in MCTNBC1, a PDX without HR gene alterations. In contrast, there was no RT-induced RAD51 foci formation in MCTNBC2, suggesting a BRCA1 mutation in the corresponding human tumor resulted in loss of HR function in that model. Conclusion: VX-970 + RT effectively radiosensitized TNBC PDXs established from both pre-treatment biopsy specimens and chemoresistant residual tumor samples and in both HR deficient and HR proficient settings. ATR inhibition should be investigated in the clinic in combination with RT for patients with residual TNBC after NAC. Citation Format: Robert W. Mutter, Mohamed M. Kahila, Xinyi Tu, Qin Zhou, Jia Yu, Krishna R. Kalari, Liewei Wang, Judy C. Boughey, Matthew P. Goetz, Jann N. Sarkaria, Zhenkun Lou. ATR inhibition is a promising radiosensitizing strategy for chemotherapy-resistant triple negative breast cancer (TNBC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 840.

Abstract 1254: Metformin's potential as a breast cancer preventative agent by altering epigenetic patterns

Abstract Metformin is one of the most commonly prescribed Type II Diabetes Mellitus (T2DM) drugs and has been shown in diabetic long-term users to reduce the likelihood of breast cancer by 56%. Breast cancer is the most commonly diagnosed cancer in the UK accounting for 55,000 new cases per year. It has been estimated that as much as 27% of cases could be prevented based on current knowledge. This study aims to investigate the novel hypothesis that metformin acts as a preventative agent by altering epigenetic patterns in non-cancerous breast epithelial cells and the T2DM environment, namely hyperinsulinemia and hyperglycaemia, potentially modulates this. Crystal Violet cell viability assay and Western Blot for p-AMPK, a known target for metformin, were performed to assess the response of two non-cancerous breast epithelial cells lines, MCF10A and MCF12A, to metformin in a range of insulin and glucose concentrations. Western blot was performed to assess changes in histone post-translational modifications (PTMs), such as H2K27ac and H3K27me3, following 3-days treatment with metformin at 2.5mM and 5mM. Additionally, we conducted an Illumina MethylationEPIC Array on MCF10A and MCF12A cell lines treated for 3-days with 2.5mM and 5mM metformin. Pyrosequencing assay was used to further validate interesting CpG sites. Our findings suggest non-cancerous breast epithelial cells, MCF10A and MCF12A cell lines, are sensitive to metformin following 3 and 7-days treatment. Further to this, our data suggests the T2DM environment impacts the effectiveness of metformin where low glucose and high insulin significantly increase metformin effectiveness in MCF10A and MCF12 cell lines following 3-day treatment, respectively. Metformin treatment leads to the activation of p-AMPK in normal breast epithelial cells. Analysis of Illumina MethylationEPIC array suggests metformin in hyperglycaemic and hyperinsulinemic conditions induces differential DNA methylation changes in MCF10A and MCF12A non-cancerous breast epithelial cell lines and the effects are dose dependent. Of the 850,000 probes, 13 CpG sites in MCF10A and 5 CpG sites in MCF12A showed significant changes in methylation following metformin treatment (p<0.001). In summary, this study has shown a potential mechanism of metformin action through altering of epigenetic patterns in non-cancerous breast epithelial cells. Future work aims to further explore epigenetic changes induced by metformin in the context of the T2DM environment and whether these changes could potentially predict reduced breast cancer risk. Citation Format: Caitriona Tyndall, Charlene Lam, Marc Gunter, James Flanagan. Metformin's potential as a breast cancer preventative agent by altering epigenetic patterns [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1254.

Pre-exposure to 50 Hz-electromagnetic fields enhanced the antiproliferative efficacy of 5-fluorouracil in breast cancer MCF-7 cells.

Resistance to 5-fluorouracil (5-FU) and its induced immune suppression have prevented its extensive application in the clinical treatment of breast cancer. In this study, the combined effect of 50 Hz-EMFs and 5-FU in the treatment of breast cancer was explored. MCF-7 and MCF10A cells were pre-exposed to 50 Hz-EMFs for 0, 2, 4, 8 and 12 h and then treated with different concentrations of 5-FU for 24 h; cell viability was analyzed by MTT assay and flow cytometry. After pre-exposure to 50 Hz-EMFs for 12 h, apoptosis and cell cycle distribution in MCF-7 and MCF10A cells were detected via flow cytometry and DNA synthesis was measured by EdU incorporation assay. Apoptosis-related and cell cycle-related gene and protein expression levels were monitored by qPCR and western blotting. Pre-exposure to 50 Hz-EMFs for 12 h enhanced the antiproliferative effect of 5-FU in breast cancer cell line MCF-7 in a dose-dependent manner but not in normal human breast epithelial cell line MCF10A. Exposure to 50 Hz-EMFs had no effect on apoptosis and P53 expression of MCF-7 and MCF10A cells, whereas it promoted DNA synthesis, induced entry of MCF-7 cells into the S phase of cell cycle, and upregulated the expression levels of cell cycle-related proteins Cyclin D1 and Cyclin E. Considering the pharmacological mechanisms of 5-FU in specifically disrupting DNA synthesis, this enhanced inhibitory effect might have resulted from the specific sensitivity of MCF7 cells in active S phase to 5-FU. Our findings demonstrate the enhanced cytotoxic activity of 5-FU on MCF7 cells through promoting entry into the S phase of the cell cycle via exposure to 50 Hz-EMFs, which provides a novel method of cancer treatment based on the combinatorial use of 50 Hz-EMFs and chemotherapy.

Potential anticancer effect of prostratin through SIK3 inhibition.

Prostratin, a phorbol ester natural plant compound, has been demonstrated to exert an anti-retroviral effect through activation of latent cluster of differentiation (CD)4+T lymphocytes and inhibition of viral entry into the cell through downregulation of chemokine receptor type 4 (CXCR4) expression. However, the potential effect of prostratin on cancer is yet to be defined. As CXCR4 is well known to induce cancer migration, it was hypothesized that prostratin induces an anti-cancer effect through inhibition of CXCR4 expression. The authors previously demonstrated that high stimulating conditions (sub-minimal IL-17, 0.1 ng/ml, synergized with high salt, Δ0.05 M NaCl) promote breast cancer cell proliferation and CXCR4 expression through upregulation of salt-inducible kinase (SIK)-3. The present study demonstrated that prostratin selectively exerted increased cytotoxicity (IC50 of 7 µM) when breast cancer cells were cultured in high stimulating conditions, compared with regular basal culture conditions (IC50 of 35 µM). Furthermore, the cytotoxic potential of prostratin was increased seven-fold in the four breast cancer cell lines (MCF-7, MDA-MB-231, BT-20 and AU-565) compared with the non-malignant MCF10A breast epithelial cell line. This suggested that prostratin specifically targets cancer cells over normal cells. Mechanistic studies revealed that prostratin inhibited CXCR4 expression in breast cancer cells through downregulation of SIK3 expression. Overall, the data suggest that prostratin is a novel drug target for the pro-oncogenic factor SIK3. These studies could form a basis for further research to evaluate the anticancer effect of prostratin in a combinatorial chemotherapeutic regimen.

Hypoxia modulates the stem cell population and induces EMT in the MCF-10A breast epithelial cell line.

A common feature among pre-malignant lesions is the induction of hypoxia through increased cell propagation and reduced access to blood flow. Hypoxia in breast cancer has been associated with poor patient prognosis, resistance to chemotherapy and increased metastasis. Although hypoxia has been correlated with factors associated with the latter stages of cancer progression, it is not well documented how hypoxia influences cells in the earliest stages of transformation. Using the immortalized MCF-10A breast epithelial cell line, we used hypoxic culture conditions to mimic reduced O2 levels found within early pre-malignant lesions and assessed various cellular parameters. In this non-transformed mammary cell line, O2 deprivation led to some changes not immediately associated with cancer progression, such as decreased proliferation, cell cycle arrest and increased apoptosis. In contrast, hypoxia did induce other changes more consistent with an increased metastatic potential. A rise in the CD44+CD24−/low-labeled cell sub-population along with increased colony forming capability indicated an expanded stem cell population. Hypoxia also induced cellular and molecular changes consistent with an epithelial-to-mesenchymal transition (EMT). Furthermore, these cells now exhibited increased migratory and invasive abilities. These results underscore the contribution of the hypoxic tumour microenvironment in cancer progression and dissemination.

Multibranched Gold Nanoparticles with Intrinsic LAT-1 Targeting Capabilities for Selective Photothermal Therapy of Breast Cancer.

Because of the critical role of the large neutral amino acid transporter-1 (LAT-1) in promoting tumor growth and proliferation, it is fast emerging as a highly attractive biomarker for the imaging and treatment of human malignancies, including breast cancer. While multibranched gold nanoparticles (AuNPs) have emerged as a promising modality in the photothermal therapy (PTT) of cancers, some of the key challenges limiting their clinical translation lie in the need to develop reproducible and cost-effective synthetic methods as well as the selective accumulation of sufficient AuNPs at tumor sites. In this study, we report a simple and direct seed-mediated synthesis of monodispersed multibranched AuNPs using the catechol-containing LAT-1 ligands, L- and D-dopa, to confer active cancer targeting. This route obviates the need for additional conjugation with targeting moieties such as peptides or antibodies. Nanoflower-like AuNPs (AuNF) with diameters of approximately 46, 70, and 90 nm were obtained and were found to possess excellent colloidal stability and biocompatibility. A significantly higher intracellular accumulation of the L- and D-dopa functionalized AuNFs was observed in a panel of breast cancer cell lines (MCF-7, MDA-MB-231, MDA-MB-468, and MDA-MB-453) when compared to the nontargeting control AuNFs synthesized with dopamine and 4-ethylcatechol. Importantly, no significant difference in uptake between the targeting and nontargeting AuNFs was observed in a non-tumorigenic MCF-10A breast epithelial cell line, hence demonstrating tumor selectivity. For PTT of breast cancer, Ag+ was introduced during synthesis to obtain L-dopa functionalized nanourchin-like AuNPs (AuNUs) with strong near-infrared (NIR) absorbance. The L-dopa functionalized AuNUs mediated selective photothermal ablation of the triple negative MDA-MB-231 breast cancer cell line and sensitized the cells to the anticancer drugs cisplatin and docetaxel. This work brings forward an effective strategy for the facile preparation of cancer targeting multibranched AuNPs with potential for the in vivo PTT of breast cancer.

Antiproliferative Properties Against Human Breast, Cervical and Ovarian Cancer Cell Lines, and Antioxidant Capacity of Leaf Aqueous Ethanolic Extract from Cotinus coggygria Scop.

Abstract Cotinus coggygria Scop. leaf aqueous ethanolic extract was examined for its in vitro antiproliferative and antioxidant activity. Antiproliferative effect was assessed on four human gynecological cancer cell lines: breast (MCF7, T47D), cervical (HeLa) and ovarian (A2780) and compared to the cell growth inhibitory effect on non-cancerous breast epithelial cell line MCF10A using MTT cell proliferation assay. Radical scavenging assay with DPPH was applied to evaluate antioxidant potential of the extract. The obtained results showed that the herb inhibited cell growth of all of the tested cancer cell lines and the highest was the cytostatic effect on A2780 cells with a half maximal inhibitory concentration (IC50) value of 30.8 μg/ml. For the other cell lines the IC50 values were in the range of 55-122.7 μg/ml. Additionally, the extract exerted considerably weaker reduction in cell proliferation of the non-cancerous cell line MCF10A compared to cancer cells, which indicates for antiproliferative selectivity. C. coggygria extract showed high free radical scavenging activity with an IC50 value of 11.2 μg/ml. The obtained data provide evidence for pharmacological potential of the tested extract and future more detailed studies concerning the molecular mechanisms of the anticancer effect of the herb are needed.

Anti-cancer stem cell activity of a sesquiterpene lactone isolated from Ambrosia arborescens and of a synthetic derivative.

New regimens are constantly being pursued in cancer treatment, especially in the context of treatment-resistant cancer stem cells (CSCs) that are assumed to be involved in cancer recurrence. Here, we investigated the anti-cancer activity of sesquiterpene lactones (SLs) isolated from Ambrosia arborescens and of synthetic derivatives in breast cancer cell lines, with a specific focus on activity against CSCs. The breast cancer cell lines MCF-7, JIMT-1, and HCC1937 and the normal-like breast epithelial cell line MCF-10A were treated with the SLs damsin and coronopilin, isolated from A. arborescens, and with ambrosin and dindol-01, synthesized using damsin. Inhibitory concentration 50 (IC50) values were obtained from dose-response curves. Based on IC50 values, doses in the μM range were used for investigating effects on cell proliferation, cell cycle phase distribution, cell death, micronuclei formation, and cell migration. Western blot analysis was used to investigate proteins involved in cell cycle regulation as well as in the NF-κB pathway since SLs have been shown to inhibit this transcription factor. Specific CSC effects were investigated using three CSC assays. All compounds inhibited cell proliferation; however, damsin and ambrosin were toxic at single-digit micromolar ranges, while higher concentrations were required for coronopilin and dindol-01. Of the four cell lines, the compounds had the least effect on the normal-like MCF-10A cells. The inhibition of cell proliferation can partly be explained by downregulation of cyclin-dependent kinase 2. All compounds inhibited tumour necrosis factor-α-induced translocation of NF-κB from the cytoplasm to the nucleus. Damsin and ambrosin treatment increased the number of micronuclei; moreover, another sign of DNA damage was the increased level of p53. Treatment with damsin and ambrosin decreased the CSC subpopulation and inhibited cell migration. Our results suggest that these compounds should be further investigated to find efficient CSC-inhibiting compounds.

Structure-based development of novel triazoles and related thiazolotriazoles as anticancer agents and Cdc25A/B phosphatase inhibitors. Synthesis, in vitro biological evaluation, molecular docking and in silico ADME-T studies

Synthesis of twenty nine new 1,2,4-triazoles and some derived thiazolothiadiazoles (structurally-relevant to some reported triazoles with anticancer and/or Cdc25A/B inhibitory activities) is described in this study. The obtained NCI's in vitro antitumor data revealed that five analogs (12, 15, 18, 19 and 22) displayed considerable tumor percentage growth inhibitory activity (GI%), among which the analog 18 possessed a special antitumor potential and spectrum. Additionally, the same five analogs showed a marginal GI effect on the normal breast epithelial cell line MCF-10A indicating higher selectivity towards cancer cells. The same active analogs 12, 15, 18, 19 and 22 were further assessed for their in vitro Cdc25A/B phosphatase inhibitory activity (a possible antitumor target), where 18 and 22 displayed a distinctive inhibitory affinity towards the Cdc25B isozyme (6.7 and 8.4 μM, respectively). Docking of 12, 15, 18, 19 and 22 with the active site of human Cdc25B phosphatase enzyme demonstrated superior binding profile by the top-scoring analog 18 relative to a reported Cdc25 phosphatase ligand. In silico calculations of molecular properties revealed that all of the active compounds comply with Lipinski's RO5 and Veber's criteria for good bioavailability suggesting good drug-likeness upon oral administration with a predicted high safety profile.

Pro-apoptotic effect of Δ2-TGZ in “claudin-1-low” triple-negative breast cancer cells: involvement of claudin-1

40% of triple-negative breast cancer (TNBC) do not express claudin-1, a major constituent of tight junction. Patients with these "claudin-1-low" tumors present a higher relapse incidence. A major challenge in oncology is the development of innovative therapies for such poor prognosis tumors. In this context, we study the anticancer effects of ∆2-TGZ, a compound derived from troglitazone (TGZ), on cell models of these tumors. In MDA-MB-231 and Hs578T "claudin-1-low" TNBC cells, Δ2-TGZ treatment induced claudin-1 protein expression and triggered apoptosis as measured by FACS analysis (annexin V/PI co-staining). Interestingly, in the non-tumorigenic human breast epithelial cell line MCF-10A, the basal level of claudin-1 was not modified following Δ2-TGZ treatment, which did not induce apoptosis. Furthermore, claudin-1-transfected MDA-MB-231 and Hs578T cells displayed a significant increase of cleaved PARP-1 and caspase 7, caspase 3/7 activities, and TUNEL staining. RNA interference was performed in order to inhibit Δ2-TGZ-induced claudin-1 expression in both the cells. In absence of claudin-1, a decrease of cleaved PARP-1 and caspase 7 and caspase 3/7 activities were observed in MDA-MB-231 but not in Hs578T cells. Claudin-1 overexpression and Δ2-TGZ treatment are associated to apoptosis in MDA-MB-231 and Hs578T "claudin-1-low" TNBC. Moreover, in MDA-MB-231 cells, claudin-1 is involved in the pro-apoptotic effect of Δ2-TGZ. Our results suggest that claudin-1 re-expression could be an interesting therapeutic strategy for "claudin-1-low" TNBC.