Patient-Derived Conditionally Reprogrammed Cells in Prostate Cancer Research.

Prostate cancer (PCa) remains a leading cause of mortality among American men, with metastatic and recurrent disease posing significant therapeutic challenges due to a limited comprehension of the underlying biological processes governing disease initiation, dormancy, and progression. The conventional use of PCa cell lines has proven inadequate in elucidating the intricate molecular mechanisms driving PCa carcinogenesis, hindering the development of effective treatments. To address this gap, patient-derived primary cell cultures have been developed and play a pivotal role in unraveling the pathophysiological intricacies unique to PCa in each individual, offering valuable insights for translational research. This review explores the applications of the conditional reprogramming (CR) cell culture approach, showcasing its capability to rapidly and effectively cultivate patient-derived normal and tumor cells. The CR strategy facilitates the acquisition of stem cell properties by primary cells, precisely recapitulating the human pathophysiology of PCa. This nuanced understanding enables the identification of novel therapeutics. Specifically, our discussion encompasses the utility of CR cells in elucidating PCa initiation and progression, unraveling the molecular pathogenesis of metastatic PCa, addressing health disparities, and advancing personalized medicine. Coupled with the tumor organoid approach and patient-derived xenografts (PDXs), CR cells present a promising avenue for comprehending cancer biology, exploring new treatment modalities, and advancing precision medicine in the context of PCa. These approaches have been used for two NCI initiatives (PDMR: patient-derived model repositories; HCMI: human cancer models initiatives).

Utilizing geospatial artificial intelligence to map cancer disparities across health regions.

We have developed an innovative tool, the Intelligent Catchment Analysis Tool (iCAT), designed to identify and address healthcare disparities across specific regions. Powered by Artificial Intelligence and Machine Learning, our tool employs a robust Geographic Information System (GIS) to map healthcare outcomes and disease disparities. iCAT allows users to query publicly available data sources, health system data, and treatment data, offering insights into gaps and disparities in diagnosis and treatment paradigms. This project aims to promote best practices to bridge the gap in healthcare access, resources, education, and economic opportunities. The project aims to engage local and regional stakeholders in data collection and evaluation, including patients, providers, and organizations. Their active involvement helps refine the platform and guides targeted interventions for more effective outcomes. In this paper, we present two sample illustrations demonstrating how iCAT identifies healthcare disparities and analyzes the impact of social and environmental variables on outcomes. Over time, this platform can help communities make decisions to optimize resource allocation.

Expression of Ezrin and Estrogen Receptors During Cervical Carcinogenesis.

RATIONALE: Development of cervical squamous carcinoma (CXCA) is accompanied by changes in estrogen receptors (ERs, ERα and ERß) and ezrin expression; however, reports have been conflicting. Using histologically documented staging of cervical biopsies, we determined ezrin and ER relationships during CXCA development. METHODS: Immunoreactive (ir) ezrin, ir-ERα, and ir-ERß were studied in normal epithelium, carcinoma in situ/cervical intraepithelial neoplasia (CIN) 1 to 3, and local invasion or metastatic CXCA. Results were compared using H scoring. Cultures of Caski metastatic CXCA cells were treated with estradiol and/or tamoxifen and studied for ER-driven ir-ezrin and the morphologic response. RESULTS: Koilocytosis was present and indicated viral presence. The ezrin H score increased from CIN1 to CIN3, reaching significant differences from normal by CIN3 ( P = .004) and 2× normal in metastatic CXCA. Estrogen receptor α and ERß H scores fell, reaching significance by CIN3 (ERα, P = .0001; ERß, P = .024). During estradiol treatment, ezrin in Caski cells increased and localized to the periphery, in ruffles and processes. The selective ER modulator tamoxifen blocked the estradiol-induced changes. CONCLUSIONS: During cervical carcinogenesis, the usual relationship between estrogen and ezrin induction is abridged. This is consistent with the effects of human papilloma virus viral proteins such as E6 and E7 that upregulate SIX1, a protein that induces ezrin. Cervical carcinogenesis is progressive but arrests at the preinvasive stage for varying lengths of time. These studies suggest that changes in ezrin may be associated with the development of the invasive phenotype and penetration of the basement membrane. They also raise the possibility that inhibiting ezrin expression could be a target for the prevention of invasive CXCA.

Sex Steroids Block the Initiation of Atherosclerosis.

Atherosclerosis is the main cause of death in men and women. This so-called "hardening of the arteries" results from advanced atherogenesis, the accumulation and death of subendothelial fat-laden macrophages (vascular plaque). The macrophages are attracted as the result of signals from injured vessels recruiting and activating cells to quell the injury by inflammation. Among the recruited cells are circulating monocytes that may be captured by the formation of neural cell adhesion molecule (nCAM) tethers between the monocytes and vascular endothelium; the tethers are dependent on electrostatic binding between distal segments of apposed nCAM molecules. The capture of monocytes is followed by their entry into the subendothelial area as macrophages, many of which will remain and become the fat-laden foam cells in vascular plaque. Neural cell adhesion molecules are subject to sialylation that blocks their electrostatic binding. We showed that estradiol-induced nCAM sialylases are present in vascular endothelial cells and tested whether sex steroid pretreatment of human vascular endothelium could inhibit the capture of monocytes. Using in vitro techniques, pretreatment of human arterial endothelial cells with estradiol, testosterone, dehydroepiandrosterone and dihydrotestosterone all induced sialylation of endothelial cells and, in a dose-response manner, reduced the capture of monocytes. Steroid hormones are protective against atherogenesis and its sequellae. Sex steroid depletion is associated with atherosclerosis. Based on this knowledge plus our results using sex steroid pretreatment of endothelial cells, we propose that the blockade of the initial step in atherogenesis by sex steroid-induced nCAM sialylation may be crucial to hormonal prevention of atherosclerosis.

Ezrin overexpression by transformed human ovarian surface epithelial cells, ovarian cleft cells, and serous ovarian adenocarcinoma cells.

OBJECTIVES: We have shown that ezrin expression correlates with ovarian epithelial cancer (OVCA) cell proliferation and metastatic behavior. In this study, we evaluated ezrin expression in transformed ovarian superficial epithelial cells (OSE) in ovarian clefts and in culture. STUDY DESIGN: Immunohistochemistry and Western blotting for immunoreactive ezrin (ir-ezrin) in normal ovarian tissue, cultured OSE, and ovarian epithelial cancer cells. RESULTS: While ir-ezrin was not demonstrable in normal cuboidal surface cells or interior ovarian organelles, cells lining the ovarian clefts strongly expressed ir-ezrin. Long-term culture of OSE increased ezrin expression and cytological abnormalities. Administration of estradiol and insulin at levels reported in inclusions dramatically induced OSE ir-ezrin expression to OVCA levels and membrane specializations; ruffling, pseudopodia and filopodia. Moreover epidermal growth factor (EGF) drastically increased ezrin translocation in OSE cells in a time-dependent manner. CONCLUSIONS: Ezrin expression by OSE increases during transformation. Ezrin expression is responsive to estradiol and growth factors previously shown to be present in ovarian inclusions. These findings suggest that the microenvironment in ovarian inclusions and clefts contributes to the development of OVCA. Our findings elaborate on the mechanism of the ovarian origin of OVCA.

Expression and activation of the membrane-cytoskeleton protein ezrin during the normal endometrial cycle.

OBJECTIVE: To examine total ezrin expression (ezrin and phospho-ezrin) through the normal endometrial cycle and to correlate ezrin activation and localization with cytologic changes. DESIGN: Experimental laboratory study. SETTING: University medical centers. PATIENT(S): Reproductive-age women. INTERVENTION(S): A total of 36 samples of normal early, mid-, and late proliferative- and secretory-phase endometrium were studied for immunoreactive total ezrin (ir-T-ezrin) and phospho-ezrin (ir-p-ezrin) expression by histology, immunohistochemistry, and Western blotting. MAIN OUTCOME MEASURE(S): Total ezrin and phospho-ezrin expressions through the normal endometrial cycle. RESULT(S): Throughout the cycle ir-T-ezrin is present in the epithelium. The intensity and localization of both ir-ezrin and ir-p-ezrin vary greatly throughout the cycle. The main findings include the following: lateral localization of ir-ezrin/ir-p-ezrin in association with membrane specializations; dense staining around secretory vacuoles (secretory phase); dense staining of the apical surfaces, including microvilli and pinopodes of epithelial cells, especially during the mid- to late secretory phases; and the presence of ezrin in the glandular secretions. Immunoreactive total ezrin and ir-p-ezrin were not expressed by stromal fibroblasts. CONCLUSION(S): Ezrin is a prominent protein in the cycling endometrium. The most striking findings were the gravitation of ir-ezrin/ir-p-ezrin to the periphery of secretory vacuoles, localization on apical surfaces of the luminal epithelium, dense ezrin staining in secretory-phase epithelial cell plumes, and the presence of ir-ezrin/ir-p-ezrin in secretory-phase luminal secretions. These findings may have functional implications, especially for implantation biology.

Economic analysis of centralized vs. decentralized electronic data capture in multi-center clinical studies.

BACKGROUND: New data management models are emerging in multi-center clinical studies. We evaluated the incremental costs associated with decentralized vs. centralized models. METHODS: We developed clinical research network economic models to evaluate three data management models: centralized, decentralized with local software, and decentralized with shared database. Descriptive information from three clinical research studies served as inputs for these models. MAIN OUTCOME MEASURES: The primary outcome was total data management costs. Secondary outcomes included: data management costs for sites, local data centers, and central coordinating centers. RESULTS: Both decentralized models were more costly than the centralized model for each clinical research study: the decentralized with local software model was the most expensive. Decreasing the number of local data centers and case book pages reduced cost differentials between models. CONCLUSION: Decentralized vs. centralized data management in multi-center clinical research studies is associated with increases in data management costs.

Estradiol regulates expression of polysialated neural cell adhesion molecule by human vascular endothelial cells.

RATIONALE: The mechanism of atherogenesis includes leukocyte adhesion to endothelial cells followed by migration into the subendothelial space. The polysialylated neural cell adhesion molecules (PSA-nCAMs) are a group of hydrophilic neural cell adhesion molecule (NCAM) isoforms that inhibit NCAM: NCAM association, thereby blocking cell: cell adhesion. During previous studies, we demonstrated that sialylation of specific NCAMs are upregulated at proestrus in the rat and that PSA-nCAM is expressed by the rat vascular endothelium. METHODS AND RESULTS: In this study, we sought the presence of PSA-nCAM in human vessels and regulation of its expression in estradiol-treated human umbilical vascular endothelial cells (HUVEC). Immunoreactive PSA-nCAM (ir-PSA-nCAM) was shown in blood and lymph vessels of adult rats and human brain, skin, liver, lung, cervix, endometrium, and ovary. Staining for ir-PSA-nCAM was present on the glycocalyceal surface of estradiol-treated HUVEC, but not in the presence of the estrogen receptor (ER)-blocker fulvestrant. Western blotting confirmed these findings. CONCLUSIONS: PSA-nCAM is widely present in the glycocalyx of human and rat vascular endothelium. It also is expressed by HUVEC, in which it is induced by estradiol. The estrogen-regulated presence of vascular PSA-nCAM could diminish NCAM-dependent interactions between vessels and circulating leukocytes, thereby impeding vascular inflammation and atherogenesis, and, contributing to estrogen-induced cardioprotection. This hypothesized action is presently under study.

Experimental and computational studies indicate specific binding of pVHL protein to Aurora-A kinase.

Overexpression of Aurora-A kinase is commonly detected in many cancers, whereas the von Hippel-Lindau protein (pVHL) is frequently mutated or absent in renal cell carcinoma and is involved in the Ub proteasome complex, an important degradation pathway. In order to establish a link between Aurora-A overexpression and lack of pVHL protein, we hypothesized that pVHL regulates Aurora-A expression through a physical interaction. We present the first evidence, from both biological assays and computational biology techniques, that human pVHL binds strongly to Aurora-A kinase. Extensive molecular modeling, docking, and dynamic simulations demonstrate that the structure of the pVHL protein would allow it to bind to the TPX2 binding region of Aurora-A. In view of Aurora-A's importance as a therapeutic target for the treatment of cancer, this observation provides novel insights into the Aurora-A/pVHL pathway. In addition, the detailed Aurora-A/pVHL binding structure obtained will be valuable for the design of future Aurora-A inhibitors as therapeutic agents.

Ab initio study of alkylation of guanine-cytosine base pair by sulfur and nitrogen mustards.

Quantum modeling of the N7(G) alkylation of guanine-cytosine (G-C) base pair by sulfur (HD) and nitrogen mustard (HN2) was performed by using the Density Functional Theory (DFT) BPW91/6-31G++DP procedure. The vibrational IR and Raman spectra are discussed with regard to the N7 position of guanine when electrophilic HD+ episulfonium and HN2+ aziridinium attack the G-C base pair. Thermodynamic and polarizability considerations are also presented. The computed electronic chemical potential and the electrophilicity of the studied species indicate that an electronic transfer is produced from the nucleophile (G-C) base pair to the electrophile HD+ episulfonium or HN2+ aziridinium during the alkylation process.

Protozoan parasite aquaporins.

Protozoan parasites are a major threat to human health with millions of fatalities worldwide, especially in nonindustrialized countries. Currently, there is no cure for many of these parasitic diseases. Consequently, there is an imperative to find treatment targets and develop novel drugs based on the proteins encoded in the genomes of these parasites. Aquaporins, members of membrane proteins discovered and characterized within the past 20 years, are the mechanism through which water is transported through living membranes. The presence of aquaporins explains disease etiology related to water physiology and presents new pharmacogenomic targets. In this article, we review the literature on aquaporins found in Apicomplexan, Kinetoplastida and Microsporidia parasites as potential drug targets. Furthermore, by analyzing protein motion dynamics, we identify impediments that need to be surmounted for developing effective drugs targeting the aquaglyceroporin of Plasmodium falciparum, the causative agent of the most fatal form of human malaria.

Estrogens regulate posttranslational modification of neural cell adhesion molecule during the estrogen-induced gonadotropin surge.

Estrogen-induced synaptic plasticity (EISP) in the periventricular area (PVA) of the hypothalamus is necessary for the preovulatory gonadotropin surge. Because in situ enzymatic desialization of hypothalamic polysialylated (PSA) neural cell adhesion molecule (NCAM) blocked EISP, we examined the presence and amount of NCAM isotopes, PSA-NCAM, and sialylation enzymes in microdissected mouse hypothalamus tissues from proestrous afternoon [peak of estrogens and nadir of arcuate nucleus (AN) synapses] and metestrous morning (nadir of estrogens and highest AN synapses). Immunohistochemistry confirmed immunoreactive (ir) PSA-NCAM staining in the perineural spaces of the PVA. The extent of staining was cycle dependent, with more dense and complete profiles of individual neurons limned by the ir-PSA-NCAM staining on proestrus and less on metestrus. Western blots showed that high levels of ir-PSA-NCAM on proestrus are accompanied by diminished ir-NCAM-140 and -180 but not ir-NCAM-120 and the reverse on metestrus (P < 0.05). To evaluate the increase of sialylated NCAM at the expense of desialylated protein, expression of the responsible polysialyltransferase enzymes polysialyltransferase (ST8Sia IV) and sialyltransferase (ST8Sia II) mRNA levels were measured using RT-PCR. Both polysialyltransferase and sialyltransferase mRNA are more abundant on proestrus than metestrus (P < 0.05), indicating that these enzymes are regulated by estrogens. These results support estrogen-regulated formation and extrusion of hydrophilic PSA-NCAM into perineural spaces in the PVA as part of the mechanism of EISP.

Influence of socioeconomic lifestyle factors and genetic polymorphism on type 2 diabetes occurrences among Tunisian Arab and Berber groups of Djerba Island.

Type 2 diabetes mellitus (T2DM) is characterized by three major metabolic abnormalities: impaired insulin-stimulated glucose uptake in muscle and adipose tissues, alterations in glucose-stimulated insulin secretion, and increased hepatic glucose production. Both genetic and environmental factors contribute to its development. The insulin gene (INS), insulin receptor gene (INSR), and insulin receptor substrate 1 gene (IRS1), identified by polymerase chain reaction and digestion with selected restriction enzymes PstI, NsiI, and BstnI, have been proposed as T2DM candidate genes. To determine the contribution of genetic and environmental factors on the occurrence of T2DM, we examined the frequency of T2DM among two ethnically diverse populations, Arabs and Berbers, who have shared the same environment, the island of Djerba, for thousands of years. Both populations have a high prevalence of obesity,T2DM, and a high consanguinity rate. A total of 162 T2DM men and women were matched to 110 healthy male and female controls. Results showed that the NsiI polymorphism in INSR and BstnI polymorphism of IRS1 were significantly associated with T2DM only among the Berber group. The PstI polymorphism in INS, was not associated with T2DM in either group. Sedentary lifestyles, lower physical activity, and lower educational levels were associated with T2DM among the Berber group. These findings suggest that the insulin receptor gene and lifestyle factors in combination may contribute to the occurrence of T2DM in the Berber portion of this island population.

Depot-medroxyprogesterone acetate: an update.

OBJECTIVE: Depo-Provera is a contraceptive approved by the US Food and Drug Administration (FDA) since 1992 and used worldwide by more than 90 million women. AIM OF STUDY: Despite the fact that progestins are endogenous hormones that are secreted by the body, its excess might lead to detrimental health effects. Whether progestins as contraceptives are friends or foes is a questionable matter. In this manuscript, we drive the attention to both usage and side effects Depo-Provera. RESULTS: Depot-medroxyprogesterone acetate (DMPA) is a highly effective, convenient non-daily hormonal contraceptive option that has been available worldwide for many years. The experience with DMPA provides a large body of long-term data regarding the efficacy and safety of this contraceptive method; this long-term experience has established that the use of DMPA does not increase the risk of cardiovascular events, breast cancer, other gynecologic malignancy, or postmenopausal fracture; however, patients are often more concerned about the relatively immediate effects of contraceptives such as potential changes in menstrual cycle, body weight, and mood disturbances. CONCLUSION: Concerns about such issues may lead to reluctance to initiate therapy or premature discontinuation. Counseling and understanding of women's concerns and experiences using Depo-Provera is important and could help health care providers redesign counseling strategies to improve contraceptive continuation and improve patient adherence.

Estrogen-induced hypothalamic synaptic plasticity and pituitary sensitization in the control of the estrogen-induced gonadotrophin surge.

Proper gonadal function requires coordinated (feedback) interactions between the gonads, adenohypophysis, and brain: the gonads elaborate sex steroids (progestins, androgens, and estrogens) and proteins (inhibin-activin family) during gamete development. In both sexes, the brain-pituitary gonadotrophin-regulating interaction is coordinated by estradiol through its opposing actions on pituitary gonadotrophs (sensitization of the response to gonadotrophin-releasing hormone [GnRH]) versus hypothalamic neurons (inhibition of GnRH secretion). This dynamic tension between the gonadotrophs and the GnRH cells in the brain regulates the circulating gonadotrophins and is termed reciprocal/negative feedback. In females, reciprocal/negative feedback dominates approximately 90% of the ovarian cycle. In a spectacular exception, the dynamic tension is broken during the surge of circulating estrogen that marks follicle and oocyte(s) maturation. The cause is an estradiol-induced disinhibition of the GnRH neurons that releases GnRH secretion to the highly sensitized pituitary gonadotrophs that in turn release the gonadotrophin surge (the estrogen-induced gonadotrophin surge [EIGS], also known as positive feedback). Studies during the past 4 decades have shown this disinhibition to result from estrogen-induced synaptic plasticity (EISP), including a reversible approximately 50% loss in arcuate nucleus synapses. The disinhibited GnRH secretion occurs during maximal gonadotroph sensitization and results in the EIGS. Specific immunoneutralization of estradiol blocks the EISP and EIGS. The EISP is accompanied by increases in insulinlike growth factor 1, polysialylated neural cell adhesion molecule, and ezrin, 3 proteins that the authors believe are the links between estrogen-induced astroglial extension and the EISP that releases GnRH secretion at the moment of maximal sensitization of the pituitary gonadotrophs. The result is the paradoxical surge of gonadotrophins at the peak of ovarian estrogen secretion and the triggering of ovulation. This enhanced understanding of the mechanics of gonadotrophin control clarifies elements of the involved feedback loops and opens the way to a better understanding of the neurobiology of reproduction.

XAF1 mediates tumor necrosis factor-alpha-induced apoptosis and X-linked inhibitor of apoptosis cleavage by acting through the mitochondrial pathway.

Tumor necrosis factor-alpha (TNF-alpha) and Fas ligand induce apoptosis by interacting with their corresponding membrane-bound death receptors and activating caspases. Since both systems share several components of the intracellular apoptotic cascade and are expressed by first trimester trophoblasts, it is unknown how these cells remain resistant to Fas ligand while sensitive to TNF-alpha. XAF1 (X-linked inhibitor of apoptosis (XIAP)-associated factor 1) is a proapoptotic protein that antagonizes the caspase-inhibitory activity of XIAP. Here, we demonstrated that XAF1 functions as an alternative pathway for TNF-alpha-induced apoptosis by translocating to the mitochondria and promoting XIAP inactivation. In addition, we showed that the overexpression of XAF1 sensitized first trimester trophoblast cells to Fas-mediated apoptosis. Furthermore, we also determined that the differential expression of XAF1 in first and third trimester trophoblast cells was due to changes in XAF1 gene methylation. Our results establish a novel regulatory pathway controlling trophoblast cell survival and provide a molecular mechanism to explain trophoblast sensitivity to TNF-alpha and the increased number of apoptotic trophoblast cells observed near term. Aberrant XAF1 expression and/or localization may have consequences for normal pregnancy outcome.

Modern pathology: protein mis-folding and mis-processing in complex disease.

Electrostatic and electrochemical properties of bio-molecules, such as proteins, are governed by energy parameters that are, in part dependent on its folding. Disruption of this process can lead to the development of complex, multisystem diseases whose presentation may be organ-dependent. Examples include cystic fibrosis, alpha-1 antitrypsin deficiency, and Alzheimer disease. In addition to explaining exotic pathologic syndromes, an understanding of protein folding mechanisms may facilitate the understanding of less complex diseases and allow the development of novel therapeutic approaches.

Direct identification of proteins from T47D cells and murine brain tissue by matrix-assisted laser desorption/ionization post-source decay/collision-induced dissociation.

The purpose of this study is to determine the feasibility of the direct matrix-assisted laser desorption/ionization (MALDI) identification of proteins in fixed T47D breast cancer cells and murine brain tissues. The ability to identify proteins from cells and tissue may lead to biomarkers that effectively predict the onset of defined disease states, and their dynamic behavior could be an important hint for drug target discoveries. Direct tissue application of trypsin allows protein identification in cells and tissues, while maintaining spatial integrity and intracellular organization. Using a chemical printer, matrix was co-registered on trypsinized human T47D breast cancer cells and cryo-preserved sections of murine brain tissue, followed by MALDI post-source decay (PSD) or MALDI collision-induced dissociation (CID), respectively. Mass-to-charge (m/z) data from the cells and brain tissues were processed using Mascot software interrogation of the National Center for Biotechnology Information (NCBI) database. Histone H2B was identified from cultured T47D human breast cancer cells. Tubulin beta2 was identified from mouse brain cortex following an induced stroke. These results suggest that MALDI PSD/CID, combined with bioinformatics, can be used for the direct identification of proteins from cells and tissues. Refinements in preparation techniques may improve this approach to provide a tool for quantitative proteomics and clinical analysis.

Mycoplasma genomics: tailoring the genome for minimal life requirements through reductive evolution.

Prokaryotic organisms of the genus Mycoplasma are characterized by their small body and genome size containing a 0.6-1.35 M bp genome. The genome is noted for its low G+C frequency ranging from 8-40 mol%. The Mycoplasma genus stems from the class Mollicutes (for soft skin), which lacks the cell walls and external motility appendages often present in other bacteria. To date, there are more than 100 known species of Mycoplasma. 34 species have been partially or completely sequenced. Widely known pathogenic species of Mycoplasma include: M. pneumoniae, causing pneumonia and other respiratory disorders, and M. genitalium, which are involved in pelvic inflammatory disease. Because of their small genome size, Mycoplasmas provide researchers a unique model of the minimal genomic requirements to maintain life. As the number of complete Mycoplasma genomes increase, these organisms become more established, thus laying the foundation for mapping evolutionary development. This manuscript provides an overview and update on Mycoplasma research, with particular focus on current genomics.

Estrogen receptor alpha interacts with Galpha13 to drive actin remodeling and endothelial cell migration via the RhoA/Rho kinase/moesin pathway.

Sex steroids control cell movement and tissue organization; however, little is known of the involved mechanisms. This report describes the ongoing dynamic regulation by estrogen of the actin cytoskeleton and cell movement in human vascular endothelial cells that depends on rapid activation of the actin-regulatory protein moesin. Moesin activation is triggered by the interaction of the C-terminal portion of cell membrane estrogen receptor alpha with the G protein Galpha(13), leading to activation of the small GTPase RhoA and of the downstream effector Rho-associated kinase. The resulting phosphorylation of moesin on Thr(558) is the means of moesin's binding to actin and the remodeling of the actin cytoskeleton. This cascade of events ensues within minutes of estradiol administration and results in changes in cell morphology and to the development of specialized cell membrane structures such as ruffles and pseudopodia that are necessary for cell movement. These findings expand our knowledge of the basis of estrogen's effects on human cells, including the regulation of actin assembly, cell movement and migration. They highlight novel pathways of signal transduction of estrogen receptor alpha through nontranscriptional mechanisms. Furthermore, exposure of this estrogen receptor-dependent, nongenomic action of estrogen on human vascular endothelial cells is especially relevant to the present interest in the role of estrogen in cardiovascular protection.