17-beta-estradiol analog inhibits cell proliferation by induction of apoptosis in breast cell lines

A modular, reversible sealing, and reusable microfluidic device for drug screening

Preclinical tests for evaluating potential drug candidates using conventional protocols can be exhaustive and high-cost processes. Microfluidic technologies that can speed up this process and allow fast screening of drugs are promising alternatives. This work presents the design, concept, and operational conditions of a simple, modular, and reversible sealing microdevice useful for drug screening. This microdevice allows for the operation of 4 parallel simultaneous conditions and can also generate a diffusive concentration gradient in sextuplicates. We used laminated polydimethylsiloxane (PDMS_LAM) and glass as building materials as proof of concept. The PDMS_LAM parts can be reused since they can be easily sterilized. We cultured MCF-7 (Michigan Cancer Foundation-7) breast cancer cells. Cells were exposed to a doxorubicin diffusive concentration gradient for 3 h. They were monitored by automated microscopy, and after data processing, it was possible to determine cell viability as a function of doxorubicin concentration. The reversible sealing enabled the recovery of the tested cells and image acquisition. Therefore, this microdevice is a promising tool for drug screening that allows assessing the cellular behavior in dynamic conditions and the recovery of cells for afterward processing and imaging.

Dysregulation of Catalase by a Sulphamoylated Estradiol Analogue Culminates in Antimitotic Activity and Cell Death Induction in Breast Cancer Cell Lines

Recent findings revealed that 2-ethyl-17-oxoestra-1,3,5(10)-trien-3-yl sulfamate (ESE-one) induces antiproliferative activity and cell rounding dependent on the generation of superoxide anion, hydrogen peroxide and peroxyl radical. In the current study, the role of these reactive oxygen species was assessed in the activity exerted by ESE-one on cell cycle progression, mitochondrial membrane potential and cell death induction in breast tumorigenic cells. The influence of ESE-one was also investigated on superoxide dismutase and catalase activity. ESE-one induced a time-dependent accumulation of cells in the G₁ phase and G₂/M phase that is partially impaired by tiron and trolox and N,N′-dimethylthiourea suggesting that superoxide anion, hydrogen peroxide and peroxyl radical are required for these effects exerted by ESE-one. Flow cytometry data in MCF-7 cells demonstrated that tiron decreased depolarization of the membrane potential in ESE-one exposed cells, indicating that superoxide anion plays a role in the depolarization effects induced by ESE-one. Spectrophotometry data showed that ESE-one decreased catalase activity in both cell lines. This study contributes towards pertinent information regarding the effects of an in silico-designed sulfamoylated compound on antioxidant enzymes leading to aberrant quantities of specific reactive oxygen species resulting in antimitotic activity culminating in the induction of cell death in breast cancer cell lines.

Sulphamoylated Estradiol Analogue Induces Reactive Oxygen Species Generation to Exert Its Antiproliferative Activity in Breast Cancer Cell Lines

2-Methoxyestradiol (2ME), a 17β-estradiol metabolite, exerts anticancer properties in vitro and in vivo. To address 2ME’s low bioavailability, research led to the in silico design of sulphamoylated 2ME analogues. However, the role of oxidative stress induced in the activity exerted by sulphamoylated compounds remains elusive. In the current study, the influence of 2-Ethyl-17-oxoestra-1,3,5(10)-trien-3-yl sulphamate (ESE-one) on reactive oxygen species (ROS) induction and its effect on cell proliferation, as well as morphology, were assessed in breast tumorigenic cells (MCF-7 and MDA-MB-231). Fluorescent microscopy showed that sulphamoylated estradiol analogues induced hydrogen peroxide and superoxide anion, correlating with decreased cell growth demonstrated by spectrophotometry data. ESE-one exposure resulted in antiproliferation which was repressed by tiron (superoxide inhibitor), trolox (peroxyl inhibitor) and N,N′-dimethylthiourea (DMTU) (hydrogen peroxide inhibitor). Morphological studies demonstrated that tiron, trolox and DMTU significantly decreased the number of rounded cells and shrunken cells in MCF-7 and MDA-MB-231 cells induced by ESE-one. This in vitro study suggests that ESE-one induces growth inhibition and cell rounding by production of superoxide anion, peroxyl radical and hydrogen peroxide. Identification of these biological changes in cancer cells caused by sulphamoylated compounds hugely contributes towards improvement of anticancer strategies and the ROS-dependent cell death pathways in tumorigenic breast cells.

Novel sulphamoylated 2-methoxy estradiol derivatives inhibit breast cancer migration by disrupting microtubule turnover and organization

BACKGROUND

The estrogen metabolite 2-methoxyestradiol (2ME2) and a number of synthesised derivatives have been shown to bind to microtubules thereby arresting cancer cells in mitosis which leads to apoptosis. In interphase cells, microtubules play an important role in the delivery of proteins to subcellular locations including the focal adhesions. In fact, focal adhesion dynamics and cell migration are in part regulated by microtubules. We hypothesised that novel 2ME2 derivatives can alter cell migration by influencing microtubule dynamics in interphase cells. In this report we describe 2ME2 derivatives that display anti-migratory capabilities in a metastatic breast cancer cell line through their effects on the microtubule network resulting in altered focal adhesion signalling and RhoA activity.

METHODS

Cell migration was assayed using wound healing assays. To eliminate mitosis blockage and cell rounding as a confounding factor cell migration was also assessed in interphase blocked cells. Fluorescence confocal microscopy was used to visualise microtubule dynamics and actin cytoskeleton organisation while western blot analysis was performed to analyse focal adhesion signalling and RhoA activation.

RESULTS

2ME2 derivatives, ESE-one and ESE-15-one, inhibited cell migration in cycling cells as expected but equally diminished migration in cells blocked in interphase. While no significant effects were observed on the actin cytoskeleton, focal adhesion kinase activity was increased while RhoA GTPase activity was inhibited after exposure to either compound. Microtubule stability was increased as evidenced by the increased length and number of detyrosinated microtubules while at the same time clear disorganisation of the normal radial microtubule organisation was observed including multiple foci.

CONCLUSIONS

ESE-15-one and ESE-one are potent migration inhibitors of metastatic breast cancer cells. This ability is coupled to alterations in focal adhesion signalling but more importantly is associated with severe disorganisation of microtubule dynamics and polarity. Therefore, these compounds may offer potential as anti-metastatic therapies.

A Novel 2-Methoxyestradiol Analogue Is Responsible for Vesicle Disruption and Lysosome Aggregation in Breast Cancer Cells

BACKGROUND

2-Methoxyestradiol (2ME2) is an endogenous metabolite of 17-β-estradiol with anti-proliferative and anti-angiogenic properties. Due to 2ME2's rapid metabolism and low oral bioavailability in in vivo settings, 2ME2 analogues have been designed to alleviate these issues. One of these compounds is 2-ethyl-3-O-sulphamoyl-estra-1,3,5(10)16-tetraene (ESE-16). A previous work alluded to the ability of ESE-16 to induce autophagic cell death. Therefore, we investigated the mode of action of ESE-16 by studying its effects on autophagy, vesicle formation, and lysosomal organisation.

SUMMARY

Vesicle formation and autophagy induction were analysed by transmission electron microscopy (TEM), monodansylcadaverine (MDC) staining and Lysotracker staining, while autophagosome turnover was analysed using microtubule-associated protein 1A/1B-light chain 3 (LC3 lipidation) analysis. MDC staining of acidic vesicles revealed an increase both in the number and size of vesicles after ESE-16 exposure. This was confirmed by TEM. Lysotracker staining indicated an increase in the size of lysosomes, as well as changes in their distribution within the cell. However, autophagy was not induced, since LC3 lipidation did not increase after exposure to ESE-16. Key -Messages: This study showed that ESE-16 exposure leads to the aggregation of acidic vesicles, identified as lysosomes, not accompanied by an induction of autophagy. Therefore, ESE-16 disrupts normal endocytic vesicle maturation likely through the inhibition of the microtubule function.

A bis-sulphamoylated estradiol derivative induces ROS-dependent cell cycle abnormalities and subsequent apoptosis

Clinical trials have revealed that the potential anticancer agent, 2-methoxyestradiol (2ME2) has limitations due to its low bioavailability. Subsequently, 2ME2 derivatives including (8R,13S,14S,17S)-2-ethyl-13-methyl-7,8,9,11,12,13,14,15,16,17-decahydro-6H-cyclopenta[a]phenanthrane-3,17-diyl bis(sulphamate) (EMBS) have shown improved efficacies in inducing apoptosis. However, no conclusive data exist to explain the mode of action exerted by these drugs. This study investigated the mode of action used by EMBS as a representative of the sulphamoylated 2ME2 derivatives. Hydrogen peroxide and superoxide production was quantified using dichlorofluorescein diacetate and hydroethidine. Cell proliferation and mitochondrial metabolism were investigated using crystal violet and Alamar Blue. Apoptosis was assessed using Annexin V-FITC while mitochondrial integrity was assessed using Mitocapture. Autophagy was visualised using LC3B II antibodies. The effects of EMBS on H2A phosphorylation and nuclei were visualised using phospho H2A antibody and 4',6-diamidino-2-phenylindole, dihydrochloride. Data showed that EMBS exposure leads to increased reactive oxygen species (ROS) production which is correlated with loss of cell proliferation, mitochondrial membrane damage, decreased metabolic activity, G2/M arrest, endoreduplication, DNA double stranded breaks, micronuclei and apoptosis induction. Treatment of EMBS-exposed cells with the ROS scavenger, N-acetyl cysteine, abrogated ROS production, cell cycle arrest and apoptosis implying an essential role for ROS production in EMBS signaling. The inhibition of c-Jun N-terminal kinase (JNK) activity also inhibited EMBS-induced apoptosis suggesting that EMBS triggers apoptosis via the JNK pathway. Lastly, evaluation of LC3IIB protein levels indicated that autophagy is not activated in EMBS-exposed cells. Our data shows that EMBS targets a pathway that leads to increased ROS production as an early event that culminates in G2/M arrest and apoptosis by means of JNK-signaling in cancer cells. This study suggests a novel oxidative stress-dependent mode of action for sulphamoylated derivatives.

Inhibition of proliferation and invasion in 2D and 3D models by 2-methoxyestradiol in human melanoma cells

Despite the recent advances in the clinical management of melanoma, there remains a need for new pharmacological approaches to treat this cancer. 2-methoxyestradiol (2ME) is a metabolite of estrogen that has shown anti-tumor effects in many cancer types. In this study we show that 2ME treatment leads to growth inhibition in melanoma cells, an effect associated with entry into senescence, decreased pRb and Cyclin B1 expression, increased p21/Cip1 expression and G2/M cell cycle arrest. 2ME treatment also inhibits melanoma cell growth in colony formation assay, including cell lines with acquired resistance to BRAF and BRAF+MEK inhibitors. We further show that 2ME is effective against melanoma with different BRAF and NRAS mutational status. Moreover, 2ME induced the retraction of cytoplasmic projections in a 3D spheroid model and significantly decreased cell proliferation in a 3D skin reconstruct model. Together our studies bring new insights into the mechanism of action of 2ME allowing melanoma targeted therapy to be further refined. Continued progress in this area is expected to lead to improved anti-cancer treatments and the development of new and more effective clinical analogues.

In vitro assessment of a computer-designed potential anticancer agent in cervical cancer cells

Background

Computer-based technology is becoming increasingly essential in biological research where drug discovery programs start with the identification of suitable drug targets. 2-Methoxyestradiol (2ME2) is a 17β-estradiol metabolite that induces apoptosis in various cancer cell lines including cervical cancer, breast cancer and multiple myeloma. Owing to 2ME2’s poor in vivo bioavailability, our laboratory in silico-designed and subsequently synthesized a novel 2ME2 analogue, 2-ethyl-3-O-sulphamoyl-estra-1,3,5(10),15-tetraen-17-ol (ESE-15-ol), using receptor- and ligand molecular modeling. In this study, the biological effects of ESE-15-ol (180 nM) and its parent molecule, 2ME2 (1 µM), were assessed on morphology and apoptosis induction in cervical cancer cells.

Results

Transmission electron microscopy, scanning electron microscopy and polarization-optical transmitted light differential interference contrast (PlasDIC) images demonstrated morphological hallmarks of apoptosis including apoptotic bodies, shrunken cells, vacuoles, reduced cell density and cell debris. Flow cytometry analysis showed apoptosis induction by means of annexin V-FITC staining. Cell cycle analysis showed that ESE-15-ol exposure resulted in a statistically significant increase in the G₂M phase (72%) compared to 2ME2 (19%). Apoptosis induction was more pronounced when cells were exposed to ESE-15-ol compared to 2ME2. Spectrophotometric analysis of caspase 8 activity demonstrated that 2ME2 and ESE-15-ol both induced caspase 8 activation by 2- and 1.7-fold respectively indicating the induction of the apoptosis. However, ESE-15-ol exerted all of the above-mentioned effects at a much lower pharmacological concentration (180 nM) compared to 2ME2 (1 µM physiological concentration).

Conclusion

Computer-based technology is essential in drug discovery and together with in vitro studies for the evaluation of these in silico-designed compounds, drug development can be improved to be cost effective and time consuming. This study evaluated the anticancer potential of ESE-15-ol, an in silico-designed compound in vitro. Research demonstrated that ESE-15-ol exerts antiproliferative activity accompanied with apoptosis induction at a nanomolar concentration compared to the micromolar range required by 2ME2. This study is the first study to demonstrate the influence of ESE-15-ol on morphology, cell cycle progression and apoptosis induction in HeLa cells. In silico-design by means of receptor- and ligand molecular modeling is thus effective in improving compound bioavailability while preserving apoptotic activity in vitro.

Ultrastructural Assessment of 2-(acridin-9-ylmethylene)-N-phenylhydrazinecarbothioamide activity on human breast adenocarcinoma cells

The aim of the present study was to investigate ultrastructural changes induced by (Z)-2-(acridin-9-ylmethylene)-N-phenylhydrazinecarbothioamide (APHCA) treatment on human breast adenocarcinoma cancer cells MCF-7, besides the evaluation of phosphatidylserine externalization and DNA fragmentation in treated cells. Cell viability analysis demonstrated concentration and time-manner cytotoxicity. Treated MCF-7 cells did not expose phosphatidylserine residues to the external plasma membrane surface and DNA fragmentation was not visualized by electrophoresis. Light microscopy showed compromised cell density and presence of vacuolization after APHCA treatment with 60μM. Scanning and transmission electron microscopies revealed hallmarks of autophagy, namely the presence of membrane bebbling and autophagosomes, besides shrunken cells and cell debris in treated MCF-7 cells. However, more specific tests such as the quantification of mammalian autophagy proteins are necessary to determine the kind of death that is trigged by APHCA.

Recent Advances in chemistry and pharmacology of 2-methoxyestradiol: An anticancer investigational drug

2-Methoxyestradiol (2ME2), an estrogen hormone metabolite is a potential cancer chemotherapeutic agent. Presently, it is an investigational drug under various phases of clinical trials alone or in combination therapy. Its anticancer activity has been attributed to its antitubulin, antiangiogenic, pro-apoptotic and ROS induction properties. This anticancer drug candidate has been explored extensively in last twenty years for its detailed chemistry and pharmacology. Present review is an update of its chemistry and biological activity. It also extends an assessment of potential of 2ME2 and its analogues as possible anticancer drug in future.

The Natural Substance MS-10 Improves and Prevents Menopausal Symptoms, Including Colpoxerosis, in Clinical Research

Many natural substances were screened to develop nutraceuticals that reduce menopausal symptoms. A complex of Cirsium japonicum var. maackii and Thymus vulgaris extracts, named MS-10, had significant positive effects. Under a low concentration of estrogen, which represents postmenopausal physiological conditions, MS-10 had beneficial effects on estrogen receptor-expressing MCF-7 cells by reversibly enhancing estrogen activity. In addition, in the ovariectomized rat model, changes in bone-specific alkaline phosphatase activity and osteocalcin, as well as low-density lipoprotein cholesterol and triglyceride levels were significantly decreased by MS-10. These results show that MS-10 protected bone health and reduced metabolic disturbances. Furthermore, in a clinical study, all menopausal symptoms, including hot flushes, parenthesis, insomnia, nervousness, melancholia, vertigo, fatigue, rheumatic pain, palpitations, formication, and headache, as well as colpoxerosis, were significantly improved by taking MS-10 for 90 days. Therefore, the evidence supports that MS-10 is an effective natural substance that can safely improve menopausal symptoms, including colpoxerosis.

Antimitotic drugs in the treatment of cancer

Cancer is a complex disease since it is adaptive in such a way that it can promote proliferation and invasion by means of an overactive cell cycle and in turn cellular division which is targeted by antimitotic drugs that are highly validated chemotherapy agents. However, antimitotic drug cytotoxicity to non-tumorigenic cells and multiple cancer resistance developed in response to drugs such as taxanes and vinca alkaloids are obstacles faced in both the clinical and basic research field to date. In this review, the classes of antimitotic compounds, their mechanisms of action and cancer cell resistance to chemotherapy and other limitations of current antimitotic compounds are highlighted, as well as the potential of novel 17-β estradiol analogs as cancer treatment.

Influence of partial and complete glutamine-and glucose deprivation of breast-and cervical tumorigenic cell lines

BACKGROUND

Due to their high proliferative requirements, tumorigenic cells possess altered metabolic systems whereby cells utilize higher quantities of glutamine and glucose. These altered metabolic requirements make it of interest to investigate the effects of physiological non-tumorigenic concentrations of glucose and glutamine on tumorigenic cells since deprivation of either results in a canonical amino acid response in mammalian cell.

METHODS

The influence of short-term exposure of tumorigenic cells to correlating decreasing glutamine- and glucose quantities were demonstrated in a highly glycolytic metastatic breast cell line and a cervical carcinoma cell line. Thereafter, cells were propagated in medium containing typical physiological concentrations of 1 mM glutamine and 6 mM glucose for 7 days. The effects on morphology were investigated by means of polarization-optical transmitted light differential interference contrast. Flow cytometry was used to demonstrate the effects of glutamine-and glucose starvation on cell cycle progression and apoptosis induction. Fluorometrics were also conducted to investigate the effects on intrinsic apoptosis induction (mitocapture), reactive oxygen species production (2,7-dichlorofluorescein diacetate) and acidic vesicle formation (acridine orange).

RESULTS

Morphological data suggests that glutamine-and glucose deprivation resulted in reduced cell density and rounded cells. Glutamine-and glucose starvation also resulted in an increase in the G2M phase and a sub-G1 peak. Complete starvation of glutamine and glucose resulted in the reduction of the mitochondrial membrane potential in both cell lines with MDA-MB-231 cells more prominently affected when compared to HeLa cells. Further, starved cells could not be rescued sufficiently by propagating since cells possessed an increase in reactive oxygen species, acidic compartments and vacuole formation.

CONCLUSION

Starvation from glutamine and glucose for short periods resulted in decreased cell density, rounded cells and apoptosis induction by means of reactive oxygen species generation and mitochondrial dysfunction. In addition, the metastatic cell line reacted more prominently to glutamine-and glucose starvation due to their highly glycolytic nature. Satisfactory cellular rescue was not possible as cells demonstrated oxidative stress and depolarized mitochondrial membrane potential. This study contributes to the knowledge regarding the in vitro effects and signal transduction of glucose and/or l-glutamine deprivation in tumorigenic cell lines.

A 2-methoxyestradiol bis-sulphamoylated derivative induces apoptosis in breast cell lines

Introduction

Research involving antimitotic compounds identified 2-methoxyestradiol (2ME2), as a promising anticancer endogenous metabolite. Owing to its low bioavailability, several in silico-designed 2ME2 analogues were synthesized. Structure-activity relationship studies indicated that an already existing 17-β-estradiol analogue, namely (8R,13S,14S,17S)-2-ethyl-13-methyl-7,8,9,11,12,13,14,15,16,17-decahydro-6H-cyclopenta[a]phenanthrane-3,17-diyl bis(sulphamate) (EMBS) to exert potential in vitro anticancer activity.

Methods

This study investigated the in vitro apoptotic influence of EMBS in an estrogen receptor-positive breast adenocarcinoma epithelial cell line (MCF-7); an estrogen receptor-negative breast epithelial cell line (MDA-MB-231) and a non-tumorigenic breast cell line (MCF-12A). Cell cycle progression, a phosphatidylserine flip, caspase 6-, 7- and 8 enzyme activity levels, Bcl-2 phosphorylation status at serine 70 and Bcl-2- and p53 protein levels were investigated to identify a possible action mechanism for apoptotic induction.

Results

The xCELLigence real-time label-independent approach revealed that EMBS exerted antiproliferative activity in all three cell lines after 24 h of exposure. A G₂M block was observed and apoptosis induction was verified by means of flow cytometry using propidium iodide and Annexin V-FITC respectively. EMBS-treated cells demonstrated a reduced mitochondrial membrane potential. EMBS exposure resulted in a statistically significant increase in p53 protein expression, decreased Bcl-2 protein expression and a decrease in pBcl-2(s70) phosphorylation status in all three cell lines. Results support the notion that EMBS induces apoptosis in all three cell lines.

Conclusion

This study includes investigation into the apoptotic hallmarks exerted by EMBS after exposure of three cell lines namely MCF-7-, MDA-MDA-231- and MCF-12A cells. Increased caspase 6-, caspase 7- and caspase 8 activities, upregulation of p53 protein expression and a decrease in phosphorylation status of Bcl-2 at serine 70 in tumorigenic and non-tumorigenic lines were demonstrated.

2-methoxyestradiol and disorders of female reproductive tissues

2-Methoxyestradiol (2ME) is an endogenous metabolite of 17β-estradiol. Once thought of as a mere degradation product, 2ME has gained attention as an important component of reproductive physiology and as a therapeutic agent in reproductive pathologies such as preeclampsia, endometriosis, infertility, and cancer. In this review, we discuss the involvement of 2ME in reproductive pathophysiology and summarize its known mechanisms of action: microtubule disruption, inhibition of angiogenesis and stimulation of apoptosis. Currently, the clinical uses of 2ME as a single agent are limited due to its poor water solubility and thus low bioavailability; however, 2ME analogs and derivatives have been recently developed and tested as cancer treatments. Despite some isolated success stories and ongoing research, 2ME derivatives have not yet provided the expected results. The adjuvant use of 2ME derivatives with chemotherapeutic agents is hindered by their intrinsic toxicity confounding the unwanted secondary effects of chemotherapy. However, due to the well-tested tolerance of the body to high doses of native 2ME, it may the combination of native 2ME with conventional treatments that will offer novel clinically relevant regimens for cancer and other reproductive disorders.