Synthesis of New Hydrazone Derivatives and Evaluation of their Efficacy as Proliferation Inhibitors in Human Cancer Cells

BACKGROUND

Hydrazine-hydrazones represent a group of bioactive compounds that display antibacterial, anti-inflammatory, antiviral or anticancer activities.

OBJECTIVE

In this study, we designed new derivative compounds from groups of hydrazones.

METHODS

The group of new derivatives was evaluated by the viability assay in human cancer and normal cells.

RESULTS

The dimethylpyridine hydrazones showed potent inhibition of cell proliferation of breast, colon cancer cells, human melanoma and glioblastoma. Compound 12 inhibited proliferation of cancer cells exhibiting a drug-resistant phenotype (MCF-7/DX and LoVoDX) at low millimolar concentrations. Whereas, antimelanoma activity was revealed by Compounds 2, 4, 7 and 12.

CONCLUSION

The present results highlighted newly synthetized hydrazine derivatives an excellent base for the design of new anticancer agents and resistance inhibitors.

Electropermeabilization of metastatic chondrosarcoma cells from primary cell culture

Primary cell cultures are challenging, but reliable model reflecting tumor response in vitro. The study was designed to examine if the increased electropermeabilization can overcame initial drug insensitivity in chondrosarcoma cells from lung metastasis. We established a primary cell culture and evaluated the cytotoxic impact of four drugs-cisplatin (CDDP), camptothecin, 2-methoxyestradiol, and leucovorin calcium (LeuCa). After determination of parameters allowing for electropermeabilization, we performed electrochemotherapy in vitro with the least toxic drugs-CDDP and LeuCa. Although combining CDDP and leucovorin together increased their toxicity and supported apoptosis, application of pulsed electric fields (PEFs) brought no advantage for their efficacy. The study emphasizes the need for introduction of primary cell cultures into studies on pulse electric fields as model frequently less sensitive to PEF-based treatments than continuous cell lines.

Valspodar-modulated chemotherapy in human ovarian cancer cells SK-OV-3 and MDAH-2774

Overcoming drug resistance in ovarian cancer is the overarching goal in gynecologic oncology. One way to increase drug cytotoxicity without increasing the drug dose is to simultaneously apply multidrug resistance modulator. Valspodar is the second generation P-glycoprotein 1 modulator capable of reversing multidrug resistance in different cancers. In this study, we evaluated the effect of valspodar and cisplatin co-treatment on cell viability, cell death and oxidative status in ovarian cancer cells. Two human ovarian cancer cell lines SK-OV-3 and MDAH-2774 were treated with cisplatin, valspodar, or cisplatin + valspodar for 24 or 48 hours. Untreated cells were used as control group. Cell viability was evaluated by MTT assay. Cell death was assessed by TUNEL and comet assay. Lipid peroxidation (malondialdehyde) and protein thiol groups were analyzed as oxidative stress markers. The expression of mitochondrial superoxide dismutase (MnSOD) was assessed by immunocytochemistry. Valspodar effectively reduced the resistance of SK-OV-3 cells to cisplatin, as demonstrated by increased oxidative stress, decreased cell viability and increased apoptosis in SK-OV-3 cells co-treated with valspodar and cisplatin compared to other groups. However, valspodar did not significantly affect the resistance of MDAH-2774 cells to cisplatin. Stronger staining for MnSOD in MDAH-2774 vs. SK-OV-3 cells after co-treatment with cisplatin and valspodar may determine the resistance of MDAH-2774 cell line to cisplatin.

Nanoemulsion Structural Design in Co-Encapsulation of Hybrid Multifunctional Agents: Influence of the Smart PLGA Polymers on the Nanosystem-Enhanced Delivery and Electro-Photodynamic Treatment

In the present study, we examined properties of poly(lactide-co-glycolide) (PLGA)-based nanocarriers (NCs) with various functional or “smart” properties, i.e., coated with PLGA, polyethylene glycolated PLGA (PEG-PLGA), or folic acid-functionalized PLGA (FA-PLGA). NCs were obtained by double emulsion (water-in-oil-in-water) evaporation process, which is one of the most suitable approaches in nanoemulsion structural design. Nanoemulsion surface engineering allowed us to co-encapsulate a hydrophobic porphyrin photosensitizing dye—verteporfin (VP) in combination with low-dose cisplatin (CisPt)—a hydrophilic cytostatic drug. The composition was tested as a multifunctional and synergistic hybrid agent for bioimaging and anticancer treatment assisted by electroporation on human ovarian cancer SKOV-3 and control hamster ovarian fibroblastoid CHO-K1 cell lines. The diameter of PLGA NCs with different coatings was on average 200 nm, as shown by dynamic light scattering, transmission electron microscopy, and atomic force microscopy. We analyzed the effect of the nanocarrier charge and the polymeric shield variation on the colloidal stability using microelectrophoretic and turbidimetric methods. The cellular internalization and anticancer activity following the electro-photodynamic treatment (EP-PDT) were assessed with confocal microscopy and flow cytometry. Our data show that functionalized PLGA NCs are biocompatible and enable efficient delivery of the hybrid cargo to cancer cells, followed by enhanced killing of cells when supported by EP-PDT.

The Cytoprotective Role of Antioxidants in Mammalian Cells Under Rapidly Varying UV Conditions During Stratospheric Balloon Campaign

The current age of dynamic development of the space industry brings the mankind closer to routine manned space flights and space tourism. This progress leads to a demand for intensive astrobiological research aimed at improving strategies of the pharmacological protection of the human cells against extreme conditions. Although routine research in space remains out of our reach, it is worth noticing that the unique severe environment of the Earth's stratosphere has been found to mimic subcosmic conditions, giving rise to the opportunity to use the stratospheric surface as a research model for the astrobiological studies. Our study included launching into the stratosphere a balloon containing mammalian normal and cancer cells treated with various compounds to examine whether these substances are capable of protecting the cells against stress caused by rapidly varying temperature, pressure, and radiation, especially UV. Owing to oxidative stress caused by irradiation and temperature shock, we used natural compounds which display antioxidant properties, namely, catechin isolated from green tea, honokiol derived from magnolia, curcumin from turmeric, and cinnamon extract. "After-flight" laboratory tests have shown the most active antioxidants as potential agents which can minimize harmful impact of extreme conditions on human cells.

Cisplatin and Vinorelbine -Mediated Electrochemotherapeutic Approach Against Multidrug Resistant Small Cell Lung Cancer (H69AR) In Vitro

BACKGROUND/AIM

Small cell lung cancer (SCLC) originates from neuroendocrine branchial cells (15-20%). It is regarded as distinct from other lung cancers due to its biological and clinical features. In most cases of SCLC, surgery or radiotherapy alone is not an effective cure. The aim of our study was to examine the cytotoxic effects of chemotherapy supported by electroporation (EP) on a resistant SCLC model, in vitro.

MATERIAL AND METHODS

The multidrug resistant small lung cell line H69AR was used to evaluate the cytotoxic effects of cisplatin (CPPD) and vinorelbine (Navirel®; NAV) at lower doses when used with EP. Cells were treated with different concentrations of CPPD and NAV, alone or in combination with the following EP parameters: 400-1200 V/cm, 8 pulses of 100 μs duration, at 1Hz. The cell viability was estimated by MTT assay after 24 and 48 h. Apoptotic cells were detected by neutral comet assay and immunofluorescence assay with PARP-6.

RESULTS

CPPD and NAV alone showed a dose-dependent effect on cell viability. Cytostatic drugs combined with EP revealed increased anticancer activity. Lower doses of CPPD or NAV delivered by EP were as effective as higher doses of these drugs without EP. The electrochemotherapeutic protocols increased the number of apoptotic cells and increased immunoreactivity of PARP-6. Our results indicated higher sensitivity of H69AR cells to NAV supported by EP.

CONCLUSION

In SCLC cells, an increased anticancer activity was potentiated by exposure of cells to high intensity electric pulses and low drug doses. It is suggested that this method could be effectively applied in the treatment of lung cancer.

Effect of electrochemotherapy with betulinic acid or cisplatin on regulation of heat shock proteins in metastatic human carcinoma cells in vitro

Betulinic acid (BTA) is naturally occurring triterpene that has received interest as a novel therapeutic substance with cytotoxicity towards a number of cancer cell lines. Despite the wide spectrum of biological and pharmacological effects, its effect may be limited its lipophobic properties. Therefore, strategies to improve the access of BTA to the cells are required to enhance the anticancer effects. Electroporation (EP) enables increased inflow of drugs into cancer cells, even at low doses, which may reduce the side effects caused by high doses of chemotherapy. The potential application of BTA in electrochemotherapy (ECT) in metastatic type of cancers was investigated in the present study. The efficacy of BTA with EP was estimated using a cell survival assay (MTT assay), microscopical morphology analysis and the immunocytochemical expression of heat shock proteins (HSPs). HSPs are molecules that protect the cell from harmful environmental, chemical and physical stresses, and ensure cell survival, recovery and proper functioning. HSP expression is induced various stress factors. Therefore, the expression of HSP27 and HSP70 was evaluated after cells were exposed to an external pulsed electric field and anticancer drugs. Facilitated drug delivery and the anticancer effect on metastatic tumor cells were evaluated in vitro. The effect of BTA was compared with cisplatin (CP), a standard cytostatic agent. Two different metastatic cancer cell lines were used, an ovary adenocarcinoma cell line (SW626) and melanoma cell line (Me45). BTA combined with EP exhibited similar efficacy to CP with EP after 24 and 48 h in SW626 and Me45 cancer cells. Me45 cells also had high HSP27 and low HSP70 immunosignals post‑ECT treatment. ECT caused increased expression of HSP27 and HSP70 proteins in SW626 cells, which were less sensitive to ECT than the Me45 melanoma cell line. The results indicate that BTA may be efficiently applied instead of CP in ECT approaches, but its activity differs between tumor cell lines.

Förster Resonance Energy Transfer-Activated Processes in Smart Nanotheranostics Fabricated in a Sustainable Manner

Multilayer nanocarriers loaded with optically activated payloads are gaining increasing attention due to their anticipated crucial role for providing new mechanisms of energy transfers in the health-oriented applications, as well as for energy storage and environmental protection. The combination of careful selection of optical components for efficient Förster resonance energy transfer, and surface engineering of the nanocarriers, allowed us to synthesize and characterize novel theranostic nanosystems for diagnosis and therapy of deep-seated tumors. The cargo, constrained within the oil core of the nanocapsules, composed of NaYF₄ :Tm⁺³ , Yb⁺³ up-converting nanoparticles together with a second-generation porphyrin-based photosensitizing agent-Verteporfin, assured requisite diagnostic and therapeutic functions under near-IR laser excitation. The outer polyaminoacid shell of the nanocapsules was functionalized with a ligand-poly(l-glutamic acid) functionalized by PEG-ylated folic acid-to ensure both a "stealth" effect and active targeting towards human breast cancer cells. The preparation criteria of all nanocarrier building blocks meet the requirements for sustainable and green chemistry practices. The multifunctionality of the proposed nanocarriers is a consequence of both the surface-functionalized organic exterior part, which was accessible for selective accumulation in cancer cells, and the hydrophobic optically active interior, which shows phototoxicity upon irradiation within the first biological window.

Calophyllum inophyllum in vaginitis treatment: Stimulated by electroporation with an in vitro approach

BACKGROUND

Vaginitis is one of the most common problems in clinical medicine and is cited most often during visits to obstetricians and gynecologists. Most of the inflammation cases are caused by candidiasis trichomoniasis and bacterial vaginosis. Therefore, treatment of vaginal infections must use antibiotic or antifungal drugs, which often provide quick relief to the patient. The real cause of the problem - disrupting the ecosystem of the vagina - remains unchanged. Thus, new therapeutic compounds are being explored.

OBJECTIVES

The aim of our study was to evaluate the effect of a natural substance: tamanu oil, an extract from the plant Calophyllum inophyllum, applied to the human fibroblast cell line (normal human dermal fibroblasts - NHDFs) and to the isolated human fibroblasts from the vagina (human vaginal fibroblasts - HVFs) in vitro.

MATERIAL AND METHODS

We evaluated the viability of cells by 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyl tetrazolium bromide (MTT) assay after incubation only with tamanu oil and with electroporation (EP). We also examined the immunocytochemical reaction of collagen type III and mitochondrial superoxide dismutase (MnSOD) under established conditions.

RESULTS

Tamanu oil increased the proliferation of cells and the amount of collagen III. It has been shown that the C. inophyllum extract stimulates the proliferation of commercial fibroblasts. For direct application in patients, one should use C. inophyllum extract in the range of 1:10-1:100 (saline dilution).

CONCLUSIONS

The use of this extract (at concentrations indicated by the studies presented here) stimulates the healing processes (increased expression of collagen type III), and has anti-inflammatory, analgesic and antiseptic qualities.

The effectiveness of chemotherapy and electrochemotherapy on ovarian cell lines in vitro

The presented study aimed to evaluate in vitro the effectiveness of improvement standard chemotherapy with bleomycin by electroporation in two various ovarian cancer cell lines. Two human ovarian cell lines OvBH-1 and SKOV-3 were used. The lines were selected because of their resistance to several therapeutic methods. As anticancer drug we use range of concentrations of bleomycin. In EP and ECT experiments different voltage values: from 0 to 1200 V/cm, 8 pulses with duration of 100μs and intervals between pulses 1s long were used. The cells viability after applied treatments was evaluated by MTT assay. The expression of heat shock proteins - HSP27 was examined by immunocytochemical ABC method.The cytotoxicity with different concentrations of bleomycin alone was not significantly decrease in both cell lines. It confirms resistance of these cells to conventional chemotherapy. The highest decrease of cell proliferation was observed after EP with bleomycin after 48h of incubation for 1000 V/cm. The intensity of expression of small heat shock proteins HSP27 slightly increased after ECT in both treated cell lines, in particular in OvBH-1. The presented study indicated that application of electroporation may effectively enhance chemotherapy with bleomycin, particularly in the case of treating ovarian cancer resistant to standard therapy.

Recent progress in the engineering of multifunctional colloidal nanoparticles for enhanced photodynamic therapy and bioimaging

This up-to-date review summarizes the design and current fabrication strategies that have been employed in the area of mono- and multifunctional colloidal nanoparticles - nanocarriers well suited for photodynamic therapy (PDT) and diagnostic purposes. Rationally engineered photosensitizer (PS)-loaded nanoparticles may be achieved via either noncovalent (i.e., self-aggregation, interfacial deposition, interfacial polymerization, or core-shell entrapment along with physical adsorption) or covalent (chemical immobilization or conjugation) processes. These PS loading approaches should provide chemical and physical stability to PS payloads. Their hydrophilic surfaces, capable of appreciable surface interactions with biological systems, can be further modified using functional groups (stealth effect) to achieve prolonged circulation in the body after administration and/or grafted by targeting agents (such as ligands, which bind to specific receptors uniquely expressed on the cell surface) or stimuli (e.g., pH, temperature, and light)-responsive moieties to improve their action and targeting efficiency. These attempts may in principle permit efficacious PDT, combination therapies, molecular diagnosis, and - in the case of nanotheranostics - simultaneous monitoring and treatment. Nanophotosensitizers (nano-PSs) should possess appropriate morphologies, sizes, unimodal distributions and surface processes to be successfully delivered to the place of action after systemic administration and should be accumulated in certain tumors by passive and/or active targeting. Additionally, physically facilitating drug delivery systems emerge as a promising approach to enhancing drug delivery, especially for the non-invasive treatment of deep-seated malignant tissues. Recent advances in nano-PSs are scrutinized, with an emphasis on design principles, via the promising use of colloid chemistry and nanotechnology.

Photodynamic therapy - mechanisms, photosensitizers and combinations

Photodynamic therapy (PDT) is a modern and non-invasive form of therapy, used in the treatment of non-oncological diseases as well as cancers of various types and locations. It is based on the local or systemic application of a photosensitive compound - the photosensitizer, which is accumulated in pathological tissues. The photosensitizer molecules absorb the light of the appropriate wavelength, initiating the activation processes leading to the selective destruction of the inappropriate cells. The photocytotoxic reactions occur only within the pathological tissues, in the area of photosensitizer distribution, enabling selective destruction. Over the last decade, a significant acceleration in the development of nanotechnology has been observed. The combination of photosensitizers with nanomaterials can improve the photodynamic therapy efficiency and eliminate its side effects as well. The use of nanoparticles enables achievement a targeted method which is focused on specific receptors, and, as a result, increases the selectivity of the photodynamic therapy. The object of this review is the anticancer application of PDT, its advantages and possible modifications to potentiate its effects.

Polymer-free cubosomes for simultaneous bioimaging and photodynamic action of photosensitizers in melanoma skin cancer cells

We designed novel polymer-free cubic bicontinuous liquid crystalline dispersions (cubosomes) using monoolein as molecular building block, phospholipids as stabilizers, propylene glycol as hydrotrope. Their kinetic stability was evaluated by analysing the backscattering profiles upon ageing, and the most stable formulation was chosen as potential photosensitizers delivery vehicle for photodynamic therapy (PDT) of human skin melanoma cells. Morphological and topological features of such formulation alternatively loaded with Chlorin e6 or meso-Tetraphenylporphine-Mn(III) chloride photosensitizing dyes were investigated by cryo-TEM, DLS, and SAXS. Bioimaging studies demonstrated that Me45 and MeWo cell lines effectively internalized these cubosomes formulations. Particularly, photodynamic activity experiments proved both the very low cytotoxicity of the cubosomes formulation loaded with Chlorin e6 dye in the "dark" condition, and its significant cytotoxic effect after photoirradiation. The toxic effect recorded when the photosensitizer was encapsulated within the cubosomes was shown to be one order of magnitude higher than that caused by the free photosensitizer. This is the first report of biocompatible polymer-free cubosomes for potential application in both PDT and bioimaging of skin malignant melanoma.

The favourable effect of catechin in electrochemotherapy in human pancreatic cancer cells

Until recently, green tea polyphenols were considered strong antioxidants. However, the latest reports have revealed that bioflavonoids can play a multiple role in anticancer therapy, including the inhibition of cell proliferation and generation of the oxidative stress in a dose-dependent manner. The presented research was designed to examine the potential of the green tea (±)-catechin as a reinforcement of the electrochemotherapy (ECT) with cisplatin in pancreatic cancer in vitro. The study was performed on two cell lines of the pancreatic ductal adenocarcinoma (PDA) - parental EPP85-181P and multidrug-resistant EPP85-181RNOV. Prior to the ECT protocol the cells were preincubated with high or low concentration of catechin for 2 or 24 hours, respectively. We assessed the influence of preincubation on the cisplatin toxicity with and without electroporation (EP), the electrosensitivity of PDA cell lines and the uptake of the daunorubicin and propidium iodide. Additionally, we evaluated the antioxidative properties of catechin by the measurement of the ROS-related fluorescence and the immunoreactivity of the oxidative stress-related enzymes superoxide dismutase (SOD2) and glutathione S-transferase (GST). We found that co-treatment with catechin can firmly enhance the efficacy of electroporation with cisplatin in vitro. More favorable effect was obtained for 2-hour incubation, which indicates the involvement of the transcriptional-independent mechanisms of catechin action. The effect may be partially explained by the increased oxidative stress level, which was higher in multidrug-resistant cells. However, further studies on cisplatin-catechin interplay and the thorough examination of the catechin-cell membrane interaction need to be performed.

Calcium electroporation for treatment of sarcoma in preclinical studies

Calcium electroporation (CaEP) describes the use of electric pulses (electroporation) to transiently permeabilize cells to allow supraphysiological doses of calcium to enter the cytosol. Calcium electroporation has successfully been investigated for treatment of cutaneous metastases in a clinical study. This preclinical study explores the possible use of calcium electroporation for treatment of sarcoma.

A normal murine muscle cell line (C2C12), and a human rhabdomyosarcoma cell line (RD) were used in the undifferentiated and differentiated state. Electroporation was performed using 8 pulses of 100 μs at 600–1000 V/cm; with calcium (0, 0.5, 1, and 5 mM). Viability was examined by MTS assay, intracellular calcium levels were measured, and expression of plasma membrane calcium ATPase (PMCA) was investigated using western blotting. Calcium/sodium exchanger (NCX1), ryanodine receptor (RyR1) expression and cytoskeleton structure (zyxin/actin) were assessed by immunofluorescence. CaEP efficiency on RD tumors was tested in vivo in immuno-deficient mice.

CaEP was significantly more efficient in RD than in normal cells. Intracellular Ca²⁺ levels after CaEP increased significantly in RD, whereas a lower increase was seen in normal cells. CaEP caused decreased expression of PMCA and NCX1 in malignant cells and RyR1 in both cell lines whereas normal cells exhibited increased expression of NCX1 after CaEP. Calcium electroporation also affected cytoskeleton structure in malignant cells.

This study showed that calcium electroporation is tolerated significantly better in normal muscle cells than sarcoma cells and as an inexpensive and simple cancer treatment this could potentially be used in connection with sarcoma surgery for local treatment.

High- and low-Molecular Weight oat Beta-Glucan Reveals Antitumor Activity in Human Epithelial Lung Cancer

Beta-glucans are widely used in treatment, cosmetics, and the food industry. Glucans play a significant role in activation of the immune and antioxidant system and inhibiting tumor proliferation. In the current study the antitumor activities of new high and low molecular weight beta-glucan derived from oats were investigated in two human lung cancer cell line (A549, H69AR) and normal keratinocytes (HaCaT). The effect of high and low molecular weight beta-glucan from oat was evaluated by cellular viability assessment, lipid peroxidation and manganese superoxide dismutase evaluation and cytoskeleton visualisation. Additionally the level of red blood cells hemolysis was performed. Our results indicate strong anti-tumor properties of new beta-glucan from oat and at the same time no toxicity for normal cells.

ANTICANCER ACTIVITY OF OAT β-GLUCAN IN COMBINATION WITH ELECTROPORATION ON HUMAN CANCER CELLS

The currently available data suggest that natural products may exert significant cytotoxic and immunomodulatory effects. Plant-derived chemotherapeutic agents such as taxol, etoposide or vincristine, currently used in cancer therapy, are prominent examples in this regard. However, there is a need for new and nat- ural anticancer compounds with low or without toxicity to normal cells. One of the active compounds responsible for the immune effects is β-glucan derived from cereals, fungi, seaweeds, yeasts and bacteria. The recent data suggest that β-glucans are potent immunomodulators with anticancer properties. Antitumor properties of fungi and yeast derived β-glucans have been widely recognized, but those polysaccharides are mostly insoluble, creating several problems especially in topical formulation. To overcome the issue of low water solubility, in the current study a more soluble β-glucan type from oats was chosen for the investigation of its antitumor activities. Cytotoxic effects were studied using a human melanoma cell line (Me45). The effect of electroporation on the antitumor activity of oat β-glucan was investigated as well. Cellular viability assessment, immuno-cytochemistry and immunofluochemistry were employed to evaluate biologic effects. Our results indicate strong anticancer properties of oat β-glucan, enhanced by electroporation.

Anticancer properties of ester derivatives of betulin in human metastatic melanoma cells (Me-45)

Background

Betulinic acid and betulin are triterpenes that have anticancer properties in various types of cancer. Unfortunately, the bioavailability and the bio-distribution of betulinic acid and its metabolic precursor, betulin are very low because of poor solubility in aqueous buffers.

Methods

In this study, we examined the anticancer properties of the ester derivatives of betulin compared to their precursors in a malignant melanoma cell line. We assessed five amino acid esters of betulin. The compounds contained four basic amino acids—natural lysine (l-Lys-OH) and three of its derivatives (l-Dap-OH, l-Dab-OH, and l-Orn-OH)—and alanine (l-Ala-OH) as a negative control (amino acid without an amine group in the side chain). The derivatives were more soluble than their precursors (betulin and betulinic acid) in water. The betulin esters were tested in the malignant melanoma cell line Me-45. To evaluate the cytotoxicity, MTT test was performed after 24, 48 and 72 h of incubation with the test compounds at a concentration range of 0.75–100 μM. For analysis of the apoptotic activity, TUNEL assay was performed. Additionally, expression of caspase-3 and PARP-1 was investigated immunocytochemically.

Results

The highest biological activity was observed with the lysine ester. The results showed that the highest cytotoxicity and the highest number of positively stained nuclei in metastatic melanoma Me-45 cells were obtained after 72 h of incubation with betulin derivatives containing lysine and ornithine.

Conclusions

The betulin ester derivatives showed enhanced antitumor activity compared to their non-modified precursors. Esters of betulin can be more potent anticancer agents than their precursor as a consequence of the rapid bioavailability and increased concentration in cancer cells.

Estrogen Receptors in Cell Membranes: Regulation and Signaling

Estrogens can stimulate the development, proliferation, migration, and survival of target cells. These biological effects are mediated through their action upon the plasma membrane estrogen receptors (ERs). ERs regulate transcriptional processes by nuclear translocation and binding to specific response elements, which leads to the regulation of gene expression. This effect is termed genomic or nuclear. However, estrogens may exert their biological activity also without direct binding to DNA and independently of gene transcription or protein synthesis. This action is called non-genomic or non-nuclear. Through non-genomic mechanisms, estrogens can modify regulatory cascades such as MAPK, P13K, and tyrosine cascade as well as membrane-associated molecules such as ion channels and G-protein-coupled receptors. The recent studies on the mechanisms of estrogen action provide an evidence that non-genomic and genomic effects converge. An example of such convergence is the potential possibility to modulate gene expression through these two independent pathways. The understanding of the plasma membrane estrogen receptors is crucial for the development of novel drugs and therapeutic protocols targeting specific receptor actions.