C16 PROPENSITY SCORE COMPARISON OF ELASTIN–BASED AND COLLAGEN–BASED MECHANICAL PROPERTIES OF AORTIC WALL IN BICUSPID VS TRICUSPID AORTIC VALVE PATIENTS UNDERGOING AORTIC SURGERY

Objective

Several studies addressed characteristics of aortic wall in patients with bicuspid aortic valve (BAV) compared to those with tricuspid aortic valve (TAV). Different patients population and lack of randomization were the main limitations in many of such studies, focused furthermore, only on ultimate properties (at rupture). In this study we compared mechanical properties in BAV and TAV patients undergoing aortic surgery using propensity score analysis to obtain two homogeneous groups of patients. We also focused on both elastin–based and collagen–based mechanical properties.

Methods

Among 87 overall patients undergoing surgery of ascending aorta, 26 were selected, following propensity score analysis, and divided in 2 groups according the type of native aortic valve (13 BAV and 13 TAV). Mechanical tests were completed following circumferential and longitudinal force application. 137 cumulative tests were accepted (93 from anterior aortic wall). Aortic wall strain (marker of elasticity) and aortic wall stress (marker of strength) were measured either in the Elastin–based (initial) distension and in the Collagen–based ultimate distension (until rupture).

Results

Cumulative comparison of specimens thickness confirmed that anterior aortic wall is thinner in BAV patients. Aortic wall thickness, however was not correlated to any of mechanical tests in Elastin–based or Collagen–based distensions. Aortic wall elasticity and strength (applying either longitudinal and circumferential force) were not different in BAV compared to TAV patients. Initial and ultimate elasticity were significantly correlated either applying circumferential and longitudinal force. Direct correlation between initial and ultimate strength, on other hands, was showed only in BAV patients when a longitudinal force was applied.

Conclusions

We clearly showed that, in dilated aorta, anterior wall is thinner in case of BAV compared to TAV. Our study, furthermore, confirms that mechanical properties of aortic wall in BAV patients are no impaired, compared to an homogeneous group of TAV patients, neither in initial or ultimate tests. Elastin–based and collagen–based aortic wall mechanical properties (under circumferential force) are directly correlated regardless BAV presence. Lack of correlation between initial and ultimate strenght in TAV patients, under a longitudinal force, needs further evaluation as it could be related to an increased frailty of aortic wall in such conditions.

Toward the improvement of 3D-printed vessels' anatomical models for robotic surgery training

Multi-Detector Computed Tomography is nowadays the gold standard for the pre-operative imaging for several surgical interventions, thanks to its excellent morphological definition. As for vascular structures, only the blood flowing inside vessels can be highlighted, while vessels' wall remains mostly invisible. Image segmentation and three-dimensional-printing technology can be used to create physical replica of patient-specific anatomy, to be used for the training of novice surgeons in robotic surgery. To this aim, it is fundamental that the model correctly resembles the morphological properties of the structure of interest, especially concerning vessels on which crucial operations are performed during the intervention. To reach the goal, vessels' actual size must be restored, including information on their wall. Starting from the correlation between vessels' lumen diameter and their wall thickness, we developed a semi-automatic approach to compute the local vessels' wall, bringing the vascular structures as close as possible to their actual size. The optimized virtual models are suitable for manufacturing by means of three-dimensional-printing technology to build patient-specific phantoms for the surgical simulation of robotic abdominal interventions. The proposed approach can effectively lead to the generation of vascular models of optimized thickness wall. The feasibility of the approach is also tested on a selection of clinical cases in abdominal surgery, on which the robotic surgery is performed on the three-dimensional-printed replica before the actual intervention.

From CT scanning to 3D printing technology: a new method for the preoperative planning of a transcutaneous bone-conduction hearing device

SUMMARY

The aim of the present study was to assess the feasibility and utility of 3D printing technology in surgical planning of a transcutaneous bone-conduction hearing device (Bonebridge^®) (BB), focusing on the identification of the proper location and placement of the transducer. 3D printed (3DP) models of three human cadaveric temporal bones, previously submitted to CT scan, were created with the representation of a topographic bone thickness map and the sinus pathway on the outer surface. The 3DP model was used to detect the most suitable location for the BB. A 3DP transparent mask that faithfully reproduced the surface of both the temporal bone and the 3DP model was also developed to correctly transfer the designated BB area. The accuracy of the procedure was verified by CT scan: a radiological marker was used to evaluate the degree of correspondence of the transducer site between the 3DP model and the human temporal bone. The BB positioning was successfully performed on all human temporal bones, with no difficulties in finding the proper location of the transducer. A mean error of 0.13 mm was found when the transducer site of the 3DP model was compared to that of the human temporal bone. The employment of 3D printing technology in surgical planning of BB positioning showed feasible results. Further studies will be required to evaluate its clinical applicability.

New frontiers and emerging applications of 3D printing in ENT surgery: a systematic review of the literature

3D printing systems have revolutionised prototyping in the industrial field by lowering production time from days to hours and costs from thousands to just a few dollars. Today, 3D printers are no more confined to prototyping, but are increasingly employed in medical disciplines with fascinating results, even in many aspects of otorhinolaryngology. All publications on ENT surgery, sourced through updated electronic databases (PubMed, MEDLINE, EMBASE) and published up to March 2017, were examined according to PRISMA guidelines. Overall, 121 studies fulfilled specific inclusion criteria and were included in our systematic review. Studies were classified according to the specific field of application (otologic, rhinologic, head and neck) and area of interest (surgical and preclinical education, customised surgical planning, tissue engineering and implantable prosthesis). Technological aspects, clinical implications and limits of 3D printing processes are discussed focusing on current benefits and future perspectives.

Role of non-genomic androgen signalling in suppressing proliferation of fibroblasts and fibrosarcoma cells

The functions of androgen receptor (AR) in stromal cells are still debated in spite of the demonstrated importance of these cells in organ development and diseases. Here, we show that physiological androgen concentration (10 nM R1881 or DHT) fails to induce DNA synthesis, while it consistently stimulates cell migration in mesenchymal and transformed mesenchymal cells. Ten nanomolar R1881 triggers p27 Ser10 phosphorylation and its stabilization in NIH3T3 fibroblasts. Activation of Rac and its downstream effector DYRK 1B is responsible for p27 Ser10 phosphorylation and cell quiescence. Ten nanomolar androgen also inhibits transformation induced by oncogenic Ras in NIH3T3 fibroblasts. Overexpression of an AR mutant unable to interact with filamin A, use of a small peptide displacing AR/filamin A interaction, and filamin A knockdown indicate that the androgen-triggered AR/filamin A complex regulates the pathway leading to p27 Ser10 phosphorylation and cell cycle arrest. As the AR/filamin A complex is also responsible for migration stimulated by 10 nM androgen, our report shows that the androgen-triggered AR/filamin A complex controls, through Rac 1, the decision of cells to halt cell cycle and migration. This study reveals a new and unexpected role of androgen/AR signalling in coordinating stromal cell functions.

Simulation of transcatheter aortic valve implantation through patient-specific finite element analysis: two clinical cases

Transcatheter aortic valve implantation (TAVI) is a minimally invasive procedure introduced to treat aortic valve stenosis in elder patients. Its clinical outcomes are strictly related to patient selection, operator skills, and dedicated pre-procedural planning based on accurate medical imaging analysis. The goal of this work is to define a finite element framework to realistically reproduce TAVI and evaluate the impact of aortic root anatomy on procedure outcomes starting from two real patient datasets. Patient-specific aortic root models including native leaflets, calcific plaques extracted from medical images, and an accurate stent geometry based on micro-tomography reconstruction are key aspects included in the present study. Through the proposed simulation strategy we observe that, in both patients, stent apposition significantly induces anatomical configuration changes, while it leads to different stress distributions on the aortic wall. Moreover, for one patient, a possible risk of paravalvular leakage has been found while an asymmetric coaptation occurs in both investigated cases. Post-operative clinical data, that have been analyzed to prove reliability of the performed simulations, show a good agreement with analysis results. The proposed work thus represents a further step towards the use of realistic computer-based simulations of TAVI procedures, aiming at improving the efficacy of the operation technique and supporting device optimization.

Patient-specific finite element analysis of carotid artery stenting: a focus on vessel modeling

Finite element analysis is nowadays a well-assessed technique to investigate the impact of stenting on vessel wall and, given the rapid progression of both medical imaging techniques and computational methods, the challenge of using the simulation of carotid artery stenting as procedure planning tool to support the clinical practice can be approached. Within this context, the present study investigates the impact of carotid stent apposition on carotid artery anatomy by means of patient-specific finite element analysis. In particular, we focus on the influence of the vessel constitutive model on the prediction of carotid artery wall tensional state of lumen gain and of vessel straightening. For this purpose, we consider, for a given stent design and CA anatomy, two constitutive models for the CA wall, that is, a hyperelastic isotropic versus a fiber-reinforced hyperelastic anisotropic model. Despite both models producing similar patterns with respect to stress distribution, the anisotropic model predicts a higher vessel straightening and a more evident discontinuity of the lumen area near the stent ends as observed in the clinical practice. Although still affected by several simplifications, the present study can be considered as further step toward a realistic simulation of carotid artery stenting.

Patient-specific aortic endografting simulation: from diagnosis to prediction

Traditional surgical repair of ascending aortic pseudoaneurysm is complex, technically challenging, and associated with significant mortality. Although new minimally invasive procedures are rapidly arising thanks to the innovations in catheter-based technologies, the endovascular repair of the ascending aorta is still limited because of the related anatomical challenges. In this context, the integration of the clinical considerations with dedicated bioengineering analysis, combining the vascular features and the prosthesis design, might be helpful to plan the procedure and predict its outcome. Moving from such considerations, in the present study we describe the use of a custom-made stent-graft to perform a fully endovascular repair of an asymptomatic ascending aortic pseudoaneurysm in a patient, who was a poor candidate for open surgery. We also discuss the possible contribution of a dedicated medical images analysis and patient-specific simulation as support to procedure planning. In particular, we have compared the simulation prediction based on pre-operative images with post-operative outcomes. The agreement between the computer-based analysis and reality encourages the use of the proposed approach for a careful planning of the treatment strategy and for an appropriate patient selection, aimed at achieving successful outcomes for endovascular treatment of ascending aortic pseudoaneurysms as well as other aortic diseases.

Tyrosine phosphorylation of estradiol receptor by Src regulates its hormone-dependent nuclear export and cell cycle progression in breast cancer cells

We report that in breast cancer cells, tyrosine phosphorylation of the estradiol receptor alpha (ERalpha) by Src regulates cytoplasmic localization of the receptor and DNA synthesis. Inhibition of Src or use of a peptide mimicking the ERalpha p-Tyr537 sequence abolishes ERalpha tyrosine phosphorylation and traps the receptor in nuclei of estradiol-treated MCF-7 cells. An ERalpha mutant carrying a mutation of Tyr537 to phenylalanine (ER537F) persistently localizes in nuclei of various cell types. In contrast with ERalpha wt, ER537F does not associate with Ran and its interaction with Crm1 is insensitive to estradiol. Thus, independently of estradiol, ER537F is retained in nuclei, where it entangles FKHR-driving cell cycle arrest. Chromatin immunoprecipitation analysis reveals that overexpression of ER537F in breast cancer cells enhances FKHR interaction with cyclin D1 promoter. This mutant also counteracts cell transformation by the activated forms of Src or PI3-K. In conclusion, in addition to regulating receptor localization, ERalpha phosphorylation by Src is required for hormone responsiveness of DNA synthesis in breast cancer cells.

Evaluation of carotid stent scaffolding through patient-specific finite element analysis

After carotid artery stenting, the plaque remains contained between the stent and the vessel wall, moving consequently physicians' concerns toward the stent capability of limiting the plaque protrusion, that is, toward vessel scaffolding, to avoid that some debris is dislodged after the procedure. Vessel scaffolding is usually measured as the cell area of the stent in free-expanded configuration, neglecting thus the actual stent configuration within the vascular anatomy. In the present study, we measure the cell area of four different stent designs deployed in a realistic carotid artery model through patient-specific finite element analysis. The results suggest that after deployment, the cell area change along the stent length and the related reduction with respect to the free-expanded configuration are functions of the vessel tapering. Hence, the conclusions withdrawn from the free-expanded configuration appear to be qualitatively acceptable for comparative purposes, but they should be carefully handled because they neglect the post-implant variability, which seems to be more pronounced in open-cell designs, especially at the bifurcation segment. Even though the investigation is limited to few stent designs and one vascular anatomy, our study confirms the capability of dedicated computer-based simulations to provide useful information about complex stent features as vessel scaffolding.

Carotid artery stenting simulation: from patient-specific images to finite element analysis

The outcome of carotid artery stenting (CAS) depends on a proper selection of patients and devices, requiring dedicated tools able to relate the device features with the target vessel. In the present study, we use finite element analysis to evaluate the performance of three self-expanding stent designs (laser-cut open-cell, laser-cut closed-cell, braided closed-cell) in a carotid artery (CA). We define six stent models considering the three designs in different sizes and configurations (i.e. straight and tapered), evaluating the stress induced in the vessel wall, the lumen gain and the vessel straightening in a patient-specific CA model based on computed angiography tomography (CTA) images. For the considered vascular anatomy and stents, the results suggest that: (i) the laser-cut closed-cell design provides a higher lumen gain; (ii) the impact of the stent configuration and of the stent oversizing is negligible with respect to the lumen gain and relevant with respect to the stress induced in the vessel wall; (iii) stent design, configuration and size have a limited impact on the vessel straightening. The presented numerical model represents a first step towards a quantitative assessment of the relation between a given carotid stent design and a given patient-specific CA anatomy.

Inhibition of the SH3 domain-mediated binding of Src to the androgen receptor and its effect on tumor growth

In human mammary and prostate cancer cells, steroid hormones or epidermal growth factor (EGF) trigger association of the androgen receptor (AR)-estradiol receptor (ER) (alpha or beta) complex with Src. This interaction activates Src and affects the G1 to S cell cycle progression. In this report, we identify the sequence responsible for the AR/Src interaction and describe a 10 amino-acid peptide that inhibits this interaction. Treatment of the human prostate or mammary cancer cells (LNCaP or MCF-7, respectively) with nanomolar concentrations of this peptide inhibits the androgen- or estradiol-induced association between the AR or the ER and Src the Src/Erk pathway activation, cyclin D1 expression and DNA synthesis, without interfering in the receptor-dependent transcriptional activity. Similarly, the peptide prevents the S phase entry of LNCaP and MCF-7 cells treated with EGF as well as mouse embryo fibroblasts stimulated with androgen or EGF. Interestingly, the peptide does not inhibit the S phase entry and cytoskeletal changes induced by EGF or serum treatment of AR-negative prostate cancer cell lines. The peptide is the first example of a specific inhibitor of steroid receptor-dependent signal transducing activity. The importance of these results is highlighted by the finding that the peptide strongly inhibits the growth of LNCaP xenografts established in nude mice.

Sex steroid hormones act as growth factors

We observed that sex steroid hormones, like growth factors, stimulate the Src/Ras/erk pathway of cell lines derived from human mammary or prostate cancers. In addition, hormone-dependent pathway activation can be induced in Cos cells, upon transfection of classic steroid receptors. Cross-talks between sex steroid receptors regulate their association with Src and consequent pathway activation. Oestradiol treatment of MCF-7 cells triggers simultaneous association of ER with Src and p85, the regulatory subunit of phosphatidylinositol-3-kinase (PI3-kinase) and activation of Src- and PI3-K-dependent pathways. Activation of the latter pathway triggers cyclin D1 transcription, that is unaffected by Mek-1 activation. This suggests that simultaneous activation of different signalling effectors is required to target different cell cycle components. Thus, a novel reciprocal cross-talk between the two pathways appears to be mediated by the ER. In all tested cells, activation of the signalling pathways has a proliferative role. Transcriptionally inactive ER expressed in NIH 3T3 cells responds to hormone causing Src/Ras/Erk pathway activation and DNA synthesis. This suggests that in these cells genomic activity is required for later events of cell growth.

Src is an initial target of sex steroid hormone action

Recent observations that steroids use pathways universally known to be regulated by growth factors and interleukins highlight the following points: (1) Steroid stimulation of the canonical pathway Src/Ras/Erk signaling from membrane to nuclei or its single members has been observed in different cell types including human cancer-derived cells, neurons, osteoblasts, osteocytes, and endothelial cells. This stimulation has been reconstituted and analyzed in transiently transfected cells. (2) Cellular context and intracellular localization of receptors are crucial in determining the biological effects evoked by this hormonal stimulation: proliferation, protection from apoptosis, and vasorelaxation. (3) Classical steroid receptors localized in the extranuclear compartment directly and, in some cases, simultaneously interact with Src. They are capable of unexpected cross talks responsible for the observed effects. (4) Other signaling pathways including P13K/AKT are also stimulated by steroids. The aim of future work will be to arrive at an integrated general view of the different signaling pathways activated by steroids and to analyze the concert between these pathways and the hormonal transcriptional action. This general view should be simultaneously verified in different cell contexts, under different physiologic and pathologic conditions. We expect that the new technologies, above all gene and protein microarray, will make this goal feasible.

PI3-kinase in concert with Src promotes the S-phase entry of oestradiol-stimulated MCF-7 cells

The p85-associated phosphatidylinositol (PI) 3-kinase/Akt pathway mediates the oestradiol-induced S-phase entry and cyclin D1 promoter activity in MCF-7 cells. Experiments with Src, p85alpha and Akt dominant-negative forms indicate that in oestradiol-treated cells these signalling effectors target the cyclin D1 promoter. Oestradiol acutely increases PI3-kinase and Akt activities in MCF-7 cells. In NIH 3T3 cells expressing ERalpha, a dominant-negative p85 suppresses hormone stimulation of Akt. The Src inhibitor, PP1, prevents hormone stimulation of Akt and PI3-kinase activities in MCF-7 cells. In turn, stimulation of Src activity is abolished in ERalpha-expressing NIH 3T3 fibroblasts by co-transfection of the dominant-negative p85alpha and in MCF-7 cells by the PI3-kinase inhibitor, LY294002. These findings indicate a novel reciprocal cross-talk between PI3-kinase and Src. Hormone stimulation of MCF-7 cells rapidly triggers association of ERalpha with Src and p85. In vitro these proteins are assembled in a ternary complex with a stronger association than that of the binary complexes composed by the same partners. The ternary complex probably favours hormone activation of Src- and PI3-kinase-dependent pathways, which converge on cell cycle progression.

Total intravenous anaesthesia without muscle relaxants in a child with diagnosed Duchenne muscular dystrophy

The case of a 3 year old child, affected by Duchenne muscular dystrophy, who underwent adenoidectomy and bilateral myringotomy, is reported. Total intravenous anaesthesia (propofol 1% infusion (160 micrograms kg-1min-1) and remifentanil (0.55 microgram kg-1min-1) without any muscle relaxants was used. The postoperative period was uneventful.

Steroid-induced androgen receptor-oestradiol receptor beta-Src complex triggers prostate cancer cell proliferation

Treatment of human prostate carcinoma-derived LNCaP cells with androgen or oestradiol triggers simultaneous association of androgen receptor and oestradiol receptor beta with Src, activates the Src/Raf-1/Erk-2 pathway and stimulates cell proliferation. Surprisingly, either androgen or oestradiol action on each of these steps is inhibited by both anti-androgens and anti-oestrogens. Similar findings for oestradiol receptor alpha were observed in MCF-7 or T47D cells stimulated by either oestradiol or androgens. Microinjection of LNCaP, MCF-7 and T47D cells with SrcK(-) abolishes steroid-stimulated S-phase entry. Data from transfected Cos cells confirm and extend the findings from these cells. Hormone-stimulated Src interaction with the androgen receptor and oestradiol receptor alpha or beta is detected using glutathione S:-transferase fusion constructs. Src SH2 interacts with phosphotyrosine 537 of oestradiol receptor alpha and the Src SH3 domain with a proline-rich stretch of the androgen receptor. The role of this phosphotyrosine is stressed by its requirement for association of oestradiol receptor alpha with Src and consequent activation of Src in intact Cos cells.

Non-transcriptional action of oestradiol and progestin triggers DNA synthesis

The recent findings that oestradiol and progestins activate the Src/Ras/Erks signalling pathway raise the question of the role of this stimulation. Microinjection experiments of human mammary cancer-derived cells (MCF-7 and T47D) with cDNA of catalytically inactive Src or anti-Ras antibody prove that Src and Ras are required for oestradiol and progestin-dependent progression of cells through the cell cycle. The antitumoral ansamycin antibiotic, geldanamycin, disrupts the steroid-induced Ras-Raf-1 association and prevents Raf-1 activation and steroid-induced DNA synthesis. Furthermore, the selective MEK 1 inhibitor, PD 98059, inhibits oestradiol and progestin stimulation of Erk-2 and the steroid-dependent S-phase entry. The MDA-MB231 cells, which do not express oestradiol receptor, fail to respond to oestradiol in terms of Erk-2 activation and S-phase entry. Fibroblasts are made equally oestradiol-responsive in terms of DNA synthesis by transient transfection with either the wild-type or the transcriptionally inactive mutant oestradiol receptor (HE241G). Co-transfection of catalytically inactive Src as well as treatment with PD98059 inhibit the oestradiol-dependent S-phase entry of fibroblasts expressing either the wild-type oestrogen receptor or its transcriptionally inactive mutant. The data presented support the view that non-transcriptional action of the two steroids plays a major role in cell cycle progression.

Activation of the Src/p21ras/Erk pathway by progesterone receptor via cross-talk with estrogen receptor

The molecular mechanisms by which ovarian hormones stimulate growth of breast tumors are unclear. It has been reported previously that estrogens activate the signal-transducing Src/p21(ras)/Erk pathway in human breast cancer cells via an interaction of estrogen receptor (ER) with c-Src. We now show that progestins stimulate human breast cancer T47D cell proliferation and induce a similar rapid and transient activation of the pathway which, surprisingly, is blocked not only by anti-progestins but also by anti-estrogens. In Cos-7 cells transfected with the B isoform of progesterone receptor (PRB), progestin activation of the MAP kinase pathway depends on co-transfection of ER. A transcriptionally inactive PRB mutant also activates the signaling pathway, demonstrating that this activity is independent of transcriptional effects. PRB does not interact with c-Src but associates via the N-terminal 168 amino acids with ER. This association is required for the signaling pathway activation by progestins. We propose that ER transmits to the Src/p21(ras)/Erk pathway signals received from the agonist-activated PRB. These findings reveal a hitherto unrecognized cross-talk between ovarian hormones which could be crucial for their growth-promoting effects on cancer cells.

Estradiol activation of human colon carcinoma-derived Caco-2 cell growth

This is the first report on estrogen-dependent growth of human-derived colon carcinoma cells. Under selected conditions, growth of subconfluent Caco-2 cells is triggered by estradiol. Cell growth is estradiol concentration dependent, with maximal effect occurring at about 0.4 nM. Growth is prevented by two different antiestrogens: the partial agonist, OH-Tamoxifen, and the pore antagonist, ICI 182,780. The growth effect is specific for estradiol since other hormonal steroids tested do not affect cell growth. The amount of estradiol receptor in subconfluent Caco-2 cells, detected by blot with monoclonal antibodies directed against the receptor as well as estradiol binding assays, is similar to that of the classical estradiol-responsive, human mammary cancer-derived MCF-7 cells. Estradiol treatment of subconfluent Caco-2 cells rapidly and reversibly stimulates four important intermediates in a signal transduction pathway that is known to trigger cell proliferation: two members of the large family of c-src-related tyrosine kinases, c-src and c-yes, and two serine/threonine kinases, the mitogen-activated protein (MAP) kinases, erk-1 and erk-2. Tyrosine kinases activated by estradiol are up-stream MAP kinases and Caco-2 cell proliferation. In fact, genistein, a specific tyrosine kinase inhibitor, abolishes the estradiol stimulatory effect on both erk-2 activity and cell proliferation. Our findings show that in subconfluent Caco-2 cells, the estradiol-receptor complex activates the c-src, c-yes/MAP kinase pathway and activates growth. This could have important implications for the understanding of human intestinal carcinogenesis.

Tyrosine kinase/p21ras/MAP-kinase pathway activation by estradiol-receptor complex in MCF-7 cells

The mechanism by which estradiol acts on cell multiplication is still unclear. Under conditions of estradiol-dependent growth, estradiol treatment of human mammary cancer MCF-7 cells triggers rapid and transient activation of the mitogen-activated (MAP) kinases, erk-1 and erk-2, increases the active form of p21ras, tyrosine phosphorylation of Shc and p190 protein and induces association of p190 to p21ras-GAP. Both Shc and p190 are substrates of activated src and once phosphorylated, they interact with other proteins and upregulate p21ras. Estradiol activates the tyrosine kinase/p21ras/MAP-kinase pathway in MCF-7 cells with kinetics which are similar to those of peptide mitogens. It is only after introduction of the human wild-type 67 kDa estradiol receptor cDNA that Cos cells become estradiol-responsive in terms of erk-2 activity. This finding, together with the inhibition by the pure anti-estrogen ICI 182 780 of the stimulatory effect of estradiol on each step of the pathway in MCF-7 cells proves that the classic estradiol receptor is responsible for the transduction pathway activation. Transfection experiments of Cos cells with the estradiol receptor cDNA and in vitro experiments with c-src show that the estradiol receptor activates c-src and this activation requires occupancy of the receptor by hormone. Our experiments suggest that c-src is an initial and integral part of the signaling events mediated by the estradiol receptor.

A 67 kDa non-hormone binding estradiol receptor is present in human mammary cancers

The presence of large amounts of a 67 kDa estradiol receptor that does not bind hormone was observed in 8 to 37 human mammary tumors (34 malignant and 3 benign). This form of receptor was detected by its conversion to hormone binding receptor by an endogenous tyrosine kinase in vitro. All 8 tumors were malignant. In these, the incubation of cytosol with ATP was seen to cause a 1- to 5-fold increase in estradiol-specific binding sites. These sites bound estradiol with physiological affinity, and their appearance was associated with tyrosine phosphorylation of estradiol receptor. The enzyme converting the non-hormone binding receptor into the hormone binding receptor is largely present in cytosol and scarce in membranes. It has been extensively purified. It is a 67 kDa protein under denaturating conditions, binds calmodulin-Sepharose in a Ca2+-dependent manner, is stimulated by Ca2+ and calmodulin, phosphorylates exogenous actin, is activated by the estradiol-receptor complex. The enzyme interacts with antibodies directed against the carboxy-terminal and catalytic domains of c-src. Therefore, it is a putative new member of the large c-src-related kinase family. Human mammary cancers with significant amounts of 67 kDa non-hormone binding receptor show relatively low levels of hormone binding estradiol receptor. The presence of non-hormone binding receptor that can be activated by in vitro tyrosine phosphorylation suggests that functional interaction of estradiol receptor with tyrosine kinases is altered in malignant tumors and has bearing on loss of hormone dependence and progression of the mammary cancer malignancy.

The role of estradiol receptor in the proliferative activity of vanadate on MCF-7 cells

Vanadate stimulates growth of the estradiol-responsive MCF-7 cells in the absence of estrogens through a mechanism requiring tyrosine kinase activity. The proliferative effect of vanadate is mediated by estradiol receptor, and is inhibited by three antiestrogens, hydroxytamoxifen, ICI 164,384, and ICI 182,780. Estradiol abolishes the inhibitory effect of ICI 164,384 or ICI 182,780. Before stimulating cell proliferation, vanadate induces accumulation of tyrosine phosphorylation in several proteins including estradiol receptor and epidermal growth factor receptor. In addition, vanadate increases the binding activity of the estradiol receptor for its ligand. This is the first evidence of in vivo association between estradiol receptor tyrosine phosphorylation and its hormone-binding activation. Antiestrogens abolish the vanadate effect on estradiol receptor and epidermal growth factor receptor phosphorylation and reduce it on general protein tyrosine phosphorylation. These findings show that vanadate, apparently through estradiol receptor tyrosine phosphorylation, triggers activity of this receptor, which in turn stimulates protein tyrosine phosphorylation and induces cell proliferation.

Immediate and transient stimulation of protein tyrosine phosphorylation by estradiol in MCF-7 cells

Estradiol stimulates protein phosphorylation on tyrosine in human breast cancer MCF-7 cells under conditions of estradiol-stimulated cell growth. The stimulatory effect of estradiol has been observed by 32P-labeling of cells followed by purification of proteins using antiphosphotyrosine antibody coupled to agarose and confirmed by immunoblotting analysis with antiphosphotyrosine antibody. This stimulation is immediate (maximal in 10 s) and transient. In addition, it is receptor-mediated since estradiol stimulation is prevented by two well-known antiestrogens, OH-Tamoxifen and ICI 164,384. Estradiol fails to stimulate tyrosine protein phosphorylation of Cos cells which do not express the estradiol receptor. Two substrates of the estrogen stimulated phosphorylation on tyrosine with approximate mol wt of 55 and 60 kDa interact with a polyclonal antibody raised against amino acids 527-533 of pp60c-src (anti-cst.1 antibody). Tyrosine kinase activity of immunoprecipitates made using either anti cst.1 antibody or the monoclonal 327 antibody specific for pp60c-src shows that kinase(s) strongly related to pp60c-src are immediately and transiently stimulated by estradiol treatment of cells. The present findings provide the first demonstration that a steroid hormone rapidly stimulates tyrosine phosphorylation of target cells and induces functional modifications of substrates of this phosphorylation. These modifications might initiate the estradiol action on cell growth.

[A new approach to the brachial plexus: clinical results]

The paper reports the results of a new brachial plexus blockade technique using a supraclavicular route which was carried out in 74 patients. From the analysis of results it can be seen that the technique is comparable to that of Moore and Winnie in terms of the success of the blockade. However, this technique appears to be safer in relation to complications such as pneumothorax and subarachnoid injection.

Properties of a purified estradiol-dependent calf uterus tyrosine kinase

A uterus tyrosine kinase has been purified to a single 67-kDa protein when analyzed by SDS-PAGE. Under nondenaturing conditions the molecular weight of the enzyme ranges from 114 to 136 kDa, depending on the procedure employed. The kinase binds calmodulin in a Ca(2+)-dependent manner and the ATP analog [(fluorosulfonyl)benzoyl]adenosine. The purified enzyme phosphorylates the phosphatase-treated uterus estradiol receptor on tyrosine and activates its hormone binding. The kinase phosphorylates actin, calmodulin, and histone H2B. Whatever the substrate, the enzymic activity is dependent on purified estradiol-receptor complex and is activated by Ca(2+)-calmodulin. The kinase activates and phosphorylates the human estradiol receptor (HEO) within the hormone binding domain (HBD) [Migliaccio, et al. (1989) Mol Endocrinol. 3, 1061-1069] as well as four of the five mutants of the HEO obtained by substituting each of the five tyrosine residues present in the HBD of the receptor with phenylalanine by site-directed mutagenesis. The mutant substituted at tyrosine 537 is the only one that is neither phosphorylated nor activated by the kinase. This proves a causal relationship between the phosphorylation of estradiol receptor on tyrosine 537 and its hormone binding activity. A synthetic peptide corresponding to 11 out of 13 amino acids surrounding tyrosine at position 537 of the human estrogen receptor can be phosphorylated by the kinase. This and other findings indicate that this kinase, unlike other tyrosine kinases, phosphorylates tyrosyl residues with acidic amino acids close to the carboxyl side.

Phosphorylation and estradiol binding of estrogen receptor in hormone-dependent and hormone-independent GR mouse mammary tumors

The effect of phosphorylation on the hormone-binding capacity of the estrogen receptor (ER) was investigated in hormone-dependent (HD) and hormone-independent (HI) mammary carcinomas of GR mice. Tumor cytosols were incubated with ATP under conditions previously used to study the tyrosine kinase which confers hormone binding to phosphatase-treated or in vitro-synthesized ER. The ATP-dependent increases in hormone-binding capacity of 8 out of 20 HI tumors ranged from values of 23 to 124 fmol/mg cytosol protein. The enhancement by ATP of hormone binding to ER was significantly less marked in HD and HR tumors than in HI tumors. In only 3 out of 13 HD and HR tumors was an increase ranging from 15 to 20 fmol/mg protein detected. Analysis by Scatchard plot of estradiol binding to ER showed that cytosol incubation of HI tumors with ATP markedly increased the hormone binding without any change in affinity. The data suggest that ER of HI tumors is less phosphorylated in vivo than the ER of HD/HR tumors, so that the receptor of HI tumors is more susceptible to gamma-32P-ATP phosphorylation and ATP-induced hormone binding in vitro. Western blot of ER with antiphosphotyrosine antibody showed that, in HI tumors, the large ATP-induced increase in hormone binding to ER was associated with phosphorylation on tyrosine of the receptor itself. Our findings indicate that the process of activation-inactivation of binding through tyrosine-phosphorylation/phosphotyrosine-dephosphorylation of ER observed in estrogen target tissues is altered in some HI mammary tumors.

In vitro phosphorylation and hormone binding activation of the synthetic wild type human estradiol receptor

A tyrosine kinase purified from calf uterus activates the hormone binding of endogenous estradiol receptor (ER) predephosphorylated and preinactivated by a nuclear phosphotyrosine phosphatase. The kinase also activates and phosphorylates the human estradiol receptor HEO synthesized in vitro, which differs from the wild type receptor HEGO because a glycine is replaced by a valine at position 400. Moreover, the kinase activates and phosphorylates a deletion mutant of HEO which consists almost exclusively of the hormone binding domain. Using HEGO and HEO in parallel and measuring both binding activation and phosphorylation of ER we now observe that the wild type receptor is a good kinase substrate, slightly better than HEO. Furthermore, HEGO like the calf uterus receptor in the presence of estradiol, stimulates the kinase. From present findings it appears that ER and uterus tyrosine kinase are functionally associated and that this association is abolished by glycine to valine substitution at position 400 of ER.

Serine phosphorylation of biosynthetic pro-urokinase from human tumor cells

Phosphorylation is a potent mechanism regulating the activity of many intracellular enzymes. We have discovered that the product of the human urokinase plasminogen activator gene, pro-uPA, is phosphorylated in serine in at least two human cell lines. Phosphorylation occurs within the cell during biosynthesis, and phosphorylated intracellular pro-uPA is secreted into the medium. Of the secreted pro-uPA molecules, 20-50% are phosphorylated in serine, thus representing a meaningful fraction of the total biosynthetic pro-uPA. Although the sites of phosphorylation have not yet been determined, at least two such sites must exist; in fact plasmin cleavage of phosphorylated single chain pro-uPA yields a two chain uPA in which both chains are phosphorylated. A specific function for pro-uPA phosphorylation has not yet been identified; however, it is tempting to speculate that, as in many other cases, phosphorylation may affect the activity of the enzyme, its response to inhibitors or the conversion of pro-uPA zymogen to active two-chain uPA. This would represent an additional way of regulating extracellular proteolysis, an important pathway involved in both intra- and extravascular phenomena like fibrinolysis, cell migration and invasiveness.

Phosphorylation on tyrosine of in vitro synthesized human estrogen receptor activates its hormone binding

Hormone binding controls the activity of estradiol receptor. The in vitro synthesized human receptor binds hormone with high affinity and low efficiency (1-4% of the maximal binding). We now report that phosphorylation on tyrosine of the synthetic receptor by an extensively purified calf uterus kinase increases hormone binding towards maximal levels without change in affinity. This is the first direct demonstration that a newly synthesized hormone receptor acquires ligand binding through phosphorylation. The use of in vitro synthesized proteins as substrates for enzymes which cause functional modifications of proteins is very promising because it is easy to identify the modified domains and residues by using deleted and point mutated proteins. Experiments with two estradiol receptor deletion mutants, one which lacks the N-terminal half of the receptor and binds hormone independently from the N-terminal half of the receptor, the other which lacks the C-terminal half of the receptor and contains the domain required to recognize the estradiol responsive elements, show that tyrosine phosphorylation occurs exclusively within or near the hormone binding domain of the receptor.

In vitro interaction of estradiol receptor with Ca2+-calmodulin

Estradiol receptor (ER) activity requires interaction with hormone and specific DNA sequence. We now report that this receptor also interacts with calmodulin (CaM), the major intracellular mediator of Ca2+ action in eucaryotic cells. This interaction has been observed using both CaM-Sepharose and [125I]CaM. Crude and purified [3H]ER complex show high affinity interaction with CaM-Sepharose [dissociation constant (Kd) 0.12 and 0.16 nM, respectively]. Unoccupied receptor shows a similar high affinity interaction. Tamoxifen-ER complex also binds to CaM-Sepharose. Several findings show that this CaM-ER interaction is very specific: lack of this interaction has been observed in the presence of trifluoperazine, an inhibitor of protein binding to CaM; the receptor binds neither Sepharose, nor parvalbumin-Sepharose; competition of interaction of [3H]ER complex with CaM-Sepharose is observed by cold ER complex; rat liver glucocorticoid receptor does not bind to CaM-Sepharose. The interaction of purified receptor with 125I-labeled CaM has been detected by various techniques: centrifugation through sucrose gradient of CaM incubated with receptor shows that CaM binds to a protein forming a complex sedimenting at 5 S. This complex is shifted to the 7.5 S region by a monoclonal antireceptor antibody. Incubation of CaM with receptor followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis fluorography of the immunoprecipitated receptor shows that [125I]CaM coprecipitates with the receptor. Competition of this interaction by an excess of cold CaM is observed. Interaction of the receptor with CaM is also observed by the overlay technique.(ABSTRACT TRUNCATED AT 250 WORDS)