Changes in high-sensitivity C-reactive protein levels and metabolic indices according to grip strength in Korean postmenopausal women.

OBJECTIVE: This study aimed to investigate the changes in high-sensitivity C-reactive protein (hs-CRP) level and metabolic indices such as blood pressure, serum lipid level and serum glucose level according to grip strength in postmenopausal women. METHOD: Data from participants (postmenopausal women) in the Seventh Korea National Health and Nutrition Examination Survey 2018 were analyzed. Absolute handgrip strength was the sum of the maximal grip strength of both hands, and relative handgrip was calculated as absolute handgrip divided by the body mass index. We performed linear regression analysis after adjusting for confounders to assess the influence of grip strength on hs-CRP level and metabolic indices. RESULTS: Linear regression analysis showed that after adjusting for confounders, with an increased absolute grip strength, systolic blood pressure and hs-CRP levels were decreased; however, the changes were not significant for the remaining indices. Relative grip strength was associated with hs-CRP levels and metabolic indices. With a high relative grip strength, hs-CRP, blood pressure, fasting blood glucose, hemoglobin A1c and triglyceride levels were decreased, while the high-density lipoprotein cholesterol level was increased. CONCLUSION: Our study evaluated the overall health status using grip strength in postmenopausal women. The grip strength adjusted by body size was suitable in evaluating the overall health status, including inflammatory and metabolic indices. Additionally, increased grip strength was associated with a better health status in postmenopausal women.

Surgeon volume and prognosis of patients with advanced papillary thyroid cancer and lateral nodal metastasis.

BACKGROUND: Surgery is the most important treatment modality for papillary thyroid cancer (PTC). However, the relationship between surgeon volume and long-term oncological outcomes has not been explored. METHODS: Patients diagnosed with N1b PTC after initial thyroid surgery between 1 July 1994 and 31 December 2011 were eligible for inclusion in the study. Surgeons were categorized into high (at least 100 operations per year) and low (fewer than 100 operations per year) volume groups. Kaplan-Meier survival analysis according to surgeon volume was performed, and Cox proportional hazard modelling was used to estimate hazard ratios (HRs) with 95 per cent confidence intervals according to patient, tumour and surgeon factors. RESULTS: A total of 1103 patients with a median follow-up of 81 (i.q.r. 62-108) months were included in the study. During follow-up, 200 patients (18·1 per cent) developed structural recurrence. A high surgeon volume was associated with low structural recurrence (P = 0·006). After adjustment for age, sex and conventional risk factors for recurrence (histology, tumour size, gross extrathyroidal extension, margin status, more than 5 positive lymph nodes, radioactive iodine therapy), the adjusted HR for structural recurrence for low-volume surgeons was 1·46 (95 per cent c.i. 1·08 to 1·96), compared with high-volume surgeons. Distant metastasis (P = 0·242) and disease-specific mortality (P = 0·288) were not affected by surgeon volume. CONCLUSION: Surgeon volume is associated with structural recurrence, but not distant metastasis or cancer-specific death in patients with N1b PTC. Surgeon volume is important in initial surgery for advanced PTC with extensive nodal metastasis in order to ensure curative outcome and reduce treatment-related morbidity.

Effects of clarithromycin on the pharmacokinetics of evogliptin in healthy volunteers.

WHAT IS KNOWN AND OBJECTIVE: Evogliptin (DA-1229), a novel dipeptidyl peptidase (DPP)-4 inhibitor with high potency and selectivity, was approved in Korea for the treatment of type 2 diabetes. Preclinical studies suggest that it is metabolized by cytochrome (CYP) P450 isozymes. Based on these findings, a clinical study was designed to investigate the pharmacokinetic (PK) interaction of evogliptin with a CYP inhibitor, clarithromycin. METHODS: An open-label, two-phase, crossover study was conducted with 12 healthy subjects. On day 1, a single dose of evogliptin 5 mg was administered alone to assess the reference PK profile of evogliptin. On day 10, after a 2-day pretreatment with clarithromycin, evogliptin 5 mg was administered again to evaluate the effect of CYP inhibition on the PK profile of evogliptin. Administration of clarithromycin continued until day 14. Blood sampling in the reference and test phases was performed until 96 and 168 hours after dosing, respectively for PK assays. RESULTS: Eleven of the 12 subjects completed the study, and their data were analysed. In the presence of clarithromycin, exposure to evogliptin increased without any serious adverse events and the geometric mean peak plasma concentration (Cmax ) and area under the concentration-time curve from time 0 extrapolated to infinity (AUC0-∞ ) of evogliptin increased by 116.5% and 89.6%, respectively. WHAT IS NEW AND CONCLUSION: Administration of clarithromycin significantly increased exposure to evogliptin in healthy subjects.

Stimulating TRPV1 externalization and synthesis in dorsal root ganglion neurons contributes to PGE2 potentiation of TRPV1 activity and nociceptor sensitization.

BACKGROUND: Persistent peripheral sensitization contributes to chronic pain. Plasticity of nociceptive dorsal root ganglion (DRG) neurons (nociceptors) induced by pro-inflammatory mediators contributes to sensitization. Prostaglandin E2 (PGE2) enriched in injured tissues is known not only directly to sensitize DRG neurons, but also to potentiate sensitizing effects of other pain mediators such as capsaicin and its receptor transient receptor potential vanilloid-1 (TRPV1). It remains unknown whether PGE2 potentiates TRPV1 activity by stimulating its synthesis, cell surface and axonal trafficking in DRG neurons. METHODS: Combined biochemical, morphological, pharmacological and behavioral approaches have been used to address this issue in both in vitro and in vivo models. RESULTS: PGE2 increased TRPV1 externalization in cultured rat DRG neurons in a time- and concentration-dependent manner, an event blocked by an inhibitor of protein synthesis or anterograde export. EP1 and EP4, but not EP2 and EP3, mediated this event. EP1 agonist-induced TRPV1 externalization was suppressed by inhibitors of CaMKII, PLC, PKC and PKCε, while EP4 agonist-induced TRPV1 externalization by inhibitors of cAMP/PKA and ERK/MAPK. Pre-exposure to PGE2 potentiated release of calcitonin gene-related peptide from cultured DRG neurons evoked by subsequent capsaicin stimulation. This event was blocked by an inhibitor of protein synthesis or export, suggesting that PGE2-induced TRPV1 synthesis and externalization is coupled to enhanced TRPV1 activity. Pre-exposure to PGE2 not only prolonged tactile allodynia evoked by subsequent capsaicin challenge, but also increased TRPV1 levels in L4-6 DRG, sciatic nerves and plantar skin. CONCLUSIONS: Our data indicate that facilitating TRPV1 synthesis, cell surface and axonal trafficking is a novel mechanism underlying PGE2 potentiation of TRPV1 activity.

Interferon consensus sequence-binding protein (ICSBP) promotes epithelial-to-mesenchymal transition (EMT)-like phenomena, cell-motility, and invasion via TGF-ß signaling in U2OS cells.

Interferon consensus sequence-binding protein (ICSBP) is a transcription factor induced by interferon gamma (IFN-γ) and a member of the interferon regulatory factor (IRF) family. ICSBP is predominantly expressed in hematopoietic cells and regulates the immune response and cell growth and differentiation. However, little is known about its function in non-hematopoietic cells. Here we show a novel function for ICSBP in epithelial-to-mesenchymal transition (EMT)-like phenomena (ELP), cell motility, and invasion in human osteosarcoma cell lines, including U2OS cells. IFN-γ treatment induced ICSBP expression and EMT-like morphological change in U2OS cells, which were suppressed by ICSBP knockdown. To further investigate the role of ICSBP in ELP, we established a stable U2OS cell line that overexpresses ICSBP. ICSBP expression caused U2OS cells to have a more elongated shape and an increased vimentin and fibronectin expression. ICSBP expression also promoted adhesiveness, motility, and invasiveness of U2OS cells. ICSBP upregulated transforming growth factor (TGF)-ß receptors and activated TGF-ß signaling cascades, which were responsible for ELP as well as increased cell motility and invasion. In addition, ICSBP-induced TGF-ß receptor activation resulted in the upregulation of Snail. Knockdown of Snail attenuated the ICSBP-induced augmentation of cell motility and invasion. Upregulation of Snail, ELP, and increased invasion by ICSBP expression were also observed in other osteosarcoma cell lines, such as Saos-2 and 143B. Furthermore, ICSBP and TGF-ß receptor I were expressed in 45/54 (84%) and 47/54 (87%) of human osteosarcoma tissues, respectively, and showed significant correlation (r=0.47, P=0.0007) with respect to their expression levels. Taken altogether, these data demonstrate a novel function for ICSBP in ELP, cell motility, and invasion through the TGF-ß and Snail signaling pathways.

Salinomycin induces cell death via inactivation of Stat3 and downregulation of Skp2.

Salinomycin has been shown to control breast cancer stem cells, although the mechanisms underlying its anticancer effects are not clear. Deregulation of cell cycle regulators play critical roles in tumorigenesis, and they have been considered as anticancer targets. In this study, we investigated salinomycin effect on cell cycle progression using OVCAR-8 ovarian cancer cell line and multidrug-resistant NCI/ADR-RES and DXR cell lines that are derived from OVCAR-8. Parental OVCAR-8 cells are sensitive to several anticancer drugs, but NCI/ADR-RES and DXR cells are resistant to several anticancer drugs. However, salinomycin caused cell growth inhibition and apoptosis via cell cycle arrest at G1 in all three cell lines. Salinomycin inhibited signal transducer and activator of transcription 3 (Stat3) activity and thus decreased expression of Stat3-target genes, including cyclin D1, Skp2, and survivin. Salinomycin induced degradation of Skp2 and thus accumulated p27Kip1. Knockdown of Skp2 further increased salinomycin-induced G1 arrest, but knockdown of p27Kip1 attenuated salinomycin effect on G1 arrest. Cdh1, an E3 ligase for Skp2, was shifted to nuclear fractions upon salinomycin treatment. Cdh1 knockdown by siRNA reversed salinomycin-induced Skp2 downregulation and p27Kip1 upregulation, indicating that salinomycin activates the APC(Cdh1)-Skp2-p27Kip1 pathway. Concomitantly, si-Cdh1 inhibited salinomycin-induced G1 arrest. Taken together, our data indicate that salinomycin induces cell cycle arrest and apoptosis via downregulation or inactivation of cell cycle-associated oncogenes, such as Stat3, cyclin D1, and Skp2, regardless of multidrug resistance.

Menin mediates epigenetic regulation via histone H3 lysine 9 methylation.

Menin, encoded by the multiple endocrine neoplasia type 1 (MEN1) gene, is a tumor suppressor that leads to multiple endocrine tumors upon loss of its function. Menin functions as a transcriptional activator by tethering MLL complex to mediate histone H3 K4 methylation. It also functions as a repressor. However, the molecular mechanism of how menin contributes to the opposite outcome in gene expression is largely unknown. Here, we investigated the role of menin in the epigenetic regulation of transcription mediated by histone covalent modification. We show that the global methylation level of histone H3 K9, as well as H3 K4, was decreased in Men1(-/-) MEF cells. Consistently, menin was able to interact with the suppressor of variegation 3-9 homolog family protein, SUV39H1, to mediate H3 K9 methylation. This interaction decreased when patient-derived MEN1 mutation was introduced into the SUV39H1-interaction domain. We show that menin mediated different chromatin changes depending on target genes. Chromatin immunoprecipitation studies showed that menin directly associated with the GBX2 promoter and menin-dependent recruitment of SUV39H1 was essential for chromatin remodeling and transcriptional regulation. These results provide a molecular basis of how menin functions as a transcriptional repressor and suggest that menin-dependent integration of H3 K9 methylation might play an important role in preventing tumors.

PTEN status switches cell fate between premature senescence and apoptosis in glioma exposed to ionizing radiation.

Loss of the tumor suppressor phosphatase and tensin homolog (PTEN) has frequently been observed in human gliomas, conferring AKT activation and resistance to ionizing radiation (IR) and drug treatments. Recent reports have shown that PTEN loss or AKT activation induces premature senescence, but many details regarding this effect remain obscure. In this study, we tested whether the status of PTEN determined fate of the cell by examining PTEN-deficient U87, U251, and U373, and PTEN-proficient LN18 and LN428 glioma cells after exposure to IR. These cells exhibited different cellular responses, senescence or apoptosis, depending on the PTEN status. We further observed that PTEN-deficient U87 cells with high levels of both AKT activation and intracellular reactive oxygen species (ROS) underwent senescence, whereas PTEN-proficient LN18 cells entered apoptosis. ROS were indispensable for inducing senescence in PTEN-deficient cells, but not for apoptosis in PTEN-proficient cells. Furthermore, transfection with wild-type (wt) PTEN or AKT small interfering RNA induced a change from premature senescence to apoptosis and depletion of p53 or p21 prevented IR-induced premature senescence in U87 cells. Our data indicate that PTEN acts as a pivotal determinant of cell fate, regarding senescence and apoptosis in IR-exposed glioma cells. We conclude that premature senescence could have a compensatory role for apoptosis in the absence of the tumor suppressor PTEN through the AKT/ROS/p53/p21 signaling pathway.

Induction of apoptosis by the ginsenoside Rh2 by internalization of lipid rafts and caveolae and inactivation of Akt.

BACKGROUND AND PURPOSE: Lipid rafts and caveolae are membrane microdomains with important roles in cell survival signalling involving the Akt pathway. Cholesterol is important for the structure and function of these microdomains. The ginsenoside Rh2 exhibits anti-tumour activity. Because Rh2 is structurally similar to cholesterol, we investigated the possibility that Rh2 exerted its anti-tumour effect by modulating rafts and caveolae. EXPERIMENTAL APPROACH: A431 cells (human epidermoid carcinoma cell line) were treated with Rh2 and the effects on cell apoptosis, raft localization and Akt activation measured. We also examined the effects of over-expression of Akt and active-Akt on Rh2-induced cell death. KEY RESULTS: Rh2 induced apoptosis concentration- and time-dependently. Rh2 reduced the levels of rafts and caveolae in the plasma membrane and increased their internalization. Furthermore, Akt activity was decreased and consequently, Akt-dependent phosphorylation of Bad, a pro-survival protein, was decreased whereas the pro-apoptotic proteins, Bim and Bax, were increased upon Rh2 treatment. Unlike microdomain internalization induce by cholesterol depletion, Rh2-mediated internalization of rafts and caveolae was not reversed by cholesterol addition. Also, cholesterol addition did not restore Akt activation or rescue cells from Rh2-induced cell death. Rh2-induced cell death was attenuated in MDA-MB-231 cells over-expressing either wild-type or dominant-active Akt. CONCLUSIONS AND IMPLICATIONS: Rh2 induced internalization of rafts and caveolae, leading to Akt inactivation, and ultimately apoptosis. Because elevated levels of membrane rafts and caveolae, and Akt activation have been correlated with cancer development, internalization of these microdomains by Rh2 could potentially be used as an anti-cancer therapy.

Effect of cooking method, distiller's grains, and vitamin E supplementation on the vitamin content of value cuts from beef steers fed wet distiller's grains and solubles and supplemental vitamin E.

Vitamin E, thiamin, riboflavin, niacin, vitamin B(6), and vitamin B(12) concentrations of flat iron steaks and petite tenders from steers fed finishing rations containing 0% and 40% corn wet distiller's grains and solubles (WDGS) with and without supplemental vitamin E were determined. Feeding treatment groups were: 0% WDGS with basal vitamin E, 0% WDGS with supplemental vitamin E (500 IU daily), 40% WDGS with basal vitamin E, and 40% WDGS and supplemental vitamin E. Cattle can be fed 40% WDGS diets more economically than corn diets. The incorporation of 40% WDGS, with and without vitamin E, was hypothesized to have little effect on the vitamin concentrations of these value meat cuts. Flat iron steaks and petite tenders were broiled and/or grilled to 70 degrees C internal temperature. Mean cooking yields ranged from 68.7% to 78.2%. The majority of the vitamin concentrations of broiled and of grilled meat were significantly different (P < 0.05) from that of raw meat. Vitamin E concentrations of raw and cooked meat from steers that received supplemental vitamin E were significantly higher (P < 0.05) than those fed basal vitamin E. Significant differences in thiamin, riboflavin, vitamin B(6), and vitamin B(12) concentrations in raw flat iron steaks and in vitamin B(6) in raw petite tenders were observed by WDGS. Thiamin, vitamin B(6), and vitamin B(12) concentrations of broiled flat iron steaks were significantly different (P < 0.05) than grilled. A few differences in vitamin concentrations of the flat iron steaks and petite tenders were observed by WDGS, vitamin E supplementation, and cooking treatments, but most of the vitamin concentrations were statistically similar.

Which oblique plane is more helpful in diagnosing an anterior cruciate ligament tear?

AIM: To evaluate the diagnostic role of additional oblique coronal and oblique sagittal magnetic resonance imaging (MRI) for an anterior cruciate ligament (ACL) tear. MATERIALS AND METHODS: A total of 101 patients who had undergone preoperative knee MRI examinations with orthogonal and two sets of oblique images were enrolled in the study. Two radiologists evaluated the MRI images by the use of four methods: orthogonal images only (method A); orthogonal and additional oblique coronal images (method B); orthogonal and oblique sagittal images (method C); and orthogonal images with oblique coronal and sagittal images (method D). The status of the ACL (normal or tear) was determined by consensus. The sensitivity, specificity, and accuracy for an ACL tear with the use of each method were calculated in comparison with arthroscopy as the reference standard, and values were statistically analysed using the McNemar test. The diagnostic accuracies were compared using receiver operating characteristic (ROC) analysis. RESULTS: Arthroscopy identified 10 partial ACL tears and 30 complete ACL tears. The specificities and accuracies for methods B, C, and D were significantly higher than the specificities and accuracies for method A (p<0.05). There was no significant difference in the sensitivity, specificity, and accuracy for methods B, C, and D. Diagnostic ability was not significantly different for each method, as determined by ROC analysis (p>0.05). CONCLUSIONS: Additional oblique imaging for an ACL tear improved the specificity. Either of the oblique imaging methods is sufficient, and no further improvement in the diagnostic efficacy was achieved by simultaneous use.

The heat-shock protein 90 inhibitor, geldanamycin, induces apoptotic cell death in Epstein-Barr virus-positive NK/T-cell lymphoma by Akt down-regulation.

NK/T-cell lymphoma (NKTL) is strongly associated with latent Epstein-Barr virus (EBV) infection. Recently, latent membrane protein 1 (LMP1), an EBV oncoprotein, was reported to activate the phosphatidylinositol-3 kinase (PI3K)/Akt pathway for cell survival. Because geldanamycin (GA) and its derivative, 17-allylamino-17-demethoxygeldanamycin (17-AAG), exhibit anti-tumour activity by degrading HSP90 client proteins, including Akt, we investigated the effect of GA and 17-AAG on the survival of NKTL cell lines. EBV-positive NKTL cell lines, Hank-1 and NK-YS, and an EBV-negative NK leukaemia cell line, NK-L, were treated with PI3K and Akt inhibitors, GA, and 17-AAG, and were subjected to apoptosis and cell viability assays, and immunoblot analysis. EBV-positive B-lymphoblastoid cell lines IM9 and LMP1-transfected IM9 (IM9-LMP1) were also included. Hank-1 and NK-YS cell viability was compromised and apoptosis was induced by LY294002 (PI3K inhibitor) or Akt inhibitor II. GA or 17-AAG administration resulted in the apoptosis of NKTL cells, accompanied by Akt and pAkt down-regulation, caspase 3 activation, and mitochondrial membrane potential disruption. The intrinsic level of pAkt was higher in EBV-positive NKTL cells than in EBV-negative NK-L, and GA or 17-AAG decreased the viability of NKTL cells more efficiently than NK-L. Moreover, IM9-LMP1 was more sensitive to Akt inhibitor II or HSP90 inhibitors than IM9. Importantly, GA showed little effect on the viability of normal peripheral NK cells as non-neoplastic counterparts for comparison. In conclusion, this study suggests that the PI3K/Akt pathway is frequently activated in EBV-positive NKTL and that therapeutic modalities based on targeting the PI3K/Akt pathway with HSP90 inhibitors could be useful for achieving NKTL control.

Promoter methylation of p16, DAPK, CDH1, and TIMP-3 genes in cervical cancer: correlation with clinicopathologic characteristics.

This study was conducted to investigate the promoter methylation status of the p16, DAPK, CDH1, and TIMP-3 genes in primary cervical cancer and its correlation with clinicopathologic characteristics. Promoter methylation was evaluated using a methylation-specific polymerase chain reaction in 78 cervical cancer tissue specimens and 24 control, normal cervical tissue specimens. Clinicopathologic parameters were obtained from medical records, and the relationship between the discrete variables and the methylation status was evaluated. The frequencies of promoter methylation of p16, DAPK, CDH1, and TIMP-3 in cervical cancer were 57%, 44.9%, 52.6%, and 9%, respectively. Primary cervical cancer had significantly higher methylation frequencies for the p16 and DAPK promoters than did the control, normal cervix (P < 0.0001). The promoter methylation of TIMP-3 was significantly higher in adenocarcinoma than in squamous cell carcinoma (41.7% vs 3%, respectively, P= 0.0175). High-stage cancers exhibited an increased promoter methylation frequency for p16 (P= 0.0061). The promoter methylation of the p16 gene is a frequent event in cervical carcinogenesis and may have potential clinical application as a marker for the progression and prognosis of cancer.

A two-year longitudinal study of dental caries in permanent first molars of Korean elementary schoolchildren.

OBJECTIVE: This longitudinal study investigated dental caries increment in permanent first molars of Korean elementary schoolchildren. METHODS: A convenience sample of 722 children aged 7-9 years attending one urban elementary school was examined at baseline, with follow-up examinations at one and two years. Coronal surfaces of permanent first molars were scored with regard to caries experience and sealant status. RESULTS: Among sound occlusal surfaces at baseline, 21 percent of upper and 25 percent of lower surfaces developed caries during the two-year interval. In teeth that erupted between baseline and the first follow-up exam, over 10 percent of occlusal surfaces developed caries. Pit and fissure caries accounted for 93 percent of all new carious surfaces, while sealants had been placed on 16 percent of occlusal surfaces during the study. CONCLUSIONS: Recognizing the limitations of this convenience sample, dental sealants should be used more widely in this Korean population, and should be applied soon after tooth eruption.

Postprandial hypertriglyceridemia impairs endothelial function by enhanced oxidant stress.

AIMS: it appears that hypertriglyceridemia (HTG) is a risk factor of atherosclerosis as demonstrated by recent studies. In this study, we analyzed the effects of acute HTG on endothelial function and oxidative stress, which are important mechanisms in the pathogenesis of atherosclerosis. METHODS AND RESULTS: in a high fat meal group (n = 11), serum triglycerides and PMA-activated leukocyte O(2)(-)* production were significantly (P < 0.005) increased from 146 +/- 69 mg/dl and 4.09 +/- 0.93 nmol/10(6) cells/min preprandially to 198 +/- 88 mg/dl and 5.49 +/- 1.19 nmol/10(6) cells/min, respectively, 2 h after eating a high-fat meal. The flow-mediated endothelium-dependent brachial artery dilation (FMD; high-resolution ultrasound) was decreased from 13.7 +/- 3.3% preprandially to 8.2 +/- 3.7%, 2 h after eating a high-fat meal (P < 0.005). However, following a low-fat meal (n = 9), there were no significant changes in triglycerides, leukocyte O(2)(-)* production and FMD. Changes of serum triglycerides were correlated negatively (r = -0.650, P < 0.005) with changes of FMD, but were correlated positively (r = 0.798, P < 0.001) with changes of leukocyte O(2)(-)* production, which - in turn - were correlated negatively (r = -0.784, P < 0.001) with changes of FMD in all study subjects (mean age: 56 years, n = 20). CONCLUSIONS: this study suggests that acute HTG causes endothelial dysfunction via enhanced oxidant stress and this may pave the way for the development of atherosclerosis under chronic conditions.

Estrogen modulation of prolactin gene expression requires an intact mitogen-activated protein kinase signal transduction pathway in cultured rat pituitary cells.

Expression of the PRL gene is regulated by many factors, including cAMP, estradiol (E2), phorbol esters, epidermal growth factor (EGF), and TRH. The promoter region of the rat PRL gene has been shown to contain DNA sequences that are thought to support the direct interaction of estrogen receptors (ERs) with DNA. It is by this direct ER/DNA interaction that estrogen is thought to modulate expression of PRL. We report here that estrogeninduced PRL expression requires an intact mitogen-activated protein kinase (MAPK) signal transduction pathway in cultured rat pituitary cells (PR1 lactotroph and GH3 somatolactotroph cell lines). Interfering with the MAPK signaling cascade by inhibiting the activity of MAPK kinase (MEK) ablates the ability of estrogen to induce PRL mRNA and protein. In these cell lines, estrogen activates extracellular regulated protein kinases ERK-1 and ERK-2 enzyme activities maximally within 10 min of 1 nM E2 treatment. This activity is blocked by pretreatment of the cells with the MEK inhibitors PD98059 and UO126. The mechanism by which ERKs-1 and -2 are activated by estrogen appears to be independent of c-Src since the effects of estrogen on PRL gene expression are not affected by herbimycin A or PP1 administration. c-Raf-1 may be involved in the effects of E2 because estrogen causes the rapid and transient tyrosine phosphorylation of c-Raf-1. The ER antagonist ICI 182,780 blocks both ERK-1 and ERK-2 activation in addition to PRL protein and mRNA, implying a central role for the classical ER in the activation of the MAPK pathway resulting in PRL gene expression.

Epidermal growth factor-stimulated tyrosine phosphorylation of caveolin-1. Enhanced caveolin-1 tyrosine phosphorylation following aberrant epidermal growth factor receptor status.

Caveolin-1 is the major coat protein of caveolae and has been reported to interact with various intracellular signaling molecules including the epidermal growth factor (EGF) receptor. To investigate the involvement of caveolin-1 in EGF receptor action, we used mouse B82L fibroblasts transfected with (a) wild type EGF receptor, (b) a C-terminally truncated EGF receptor at residue 1022, (c) a C-terminally truncated EGF receptor at residue 973, or (d) a kinase-inactive EGF receptor (K721M). Following EGF treatment, there was a distinct electrophoretic mobility shift of the caveolin-1 present in cells expressing the truncated forms of the EGF receptor, but this shift was not detectable in cells bearing either normal levels of the wild type EGF receptor or a kinase-inactive receptor. This mobility shift was also not observed following the addition of other cell stimuli, such as platelet-derived growth factor, insulin, basic fibroblast growth factor, or phorbol 12-myristate 13-acetate. Analysis of caveolin-1 immunoprecipitates from EGF-stimulated or nonstimulated cells demonstrated that the EGF-induced mobility shift of caveolin-1 was associated with its tyrosine phosphorylation in cells expressing truncated EGF receptors. Maximal caveolin-1 phosphorylation was achieved within 5 min after exposure to 10 nM EGF and remained elevated for at least 2 h. Additionally, several distinct phosphotyrosine-containing proteins (60, 45, 29, 24, and 20 kDa) were co-immunoprecipitated with caveolin-1 in an EGF-dependent manner. Furthermore, the Src family kinase inhibitor, PP1, does not affect autophosphorylation of the receptor, but it does inhibit the EGF-induced mobility shift and phosphorylation of caveolin-1. Conversely, the MEK inhibitors PD98059 and UO126 could attenuate EGF-induced mitogen-activated protein kinase activation, they do not affect the EGF-induced mobility shift of caveolin-1. Because truncation and overexpression of the EGF receptor have been linked to cell transformation, these results provide the first evidence that the tyrosine phosphorylation of caveolin-1 occurs via an EGF-sensitive signaling pathway that can be potentiated by an aberrant activity or expression of various forms of the EGF receptor.

Platelet-derived growth factor-stimulated migration of murine fibroblasts is associated with epidermal growth factor receptor expression and tyrosine phosphorylation.

Previous studies have shown that epidermal growth factor (EGF) synergizes with various extracellular matrix components in promoting the migration of B82L fibroblasts expressing wild-type EGF receptors and that functional EGF receptors are critical for the conversion of B82L fibroblasts to a migratory cell type (). In the present study, we examined the effects of platelet-derived growth factor (PDGF) on the motility of B82L fibroblasts using a microchemotaxis chamber. We found that PDGF can enhance fibronectin-induced migration of B82L fibroblasts expressing wild-type EGF receptors (B82L-clone B3). However, B82L cells that lack the EGF receptor (B82L-parental) or that express an EGF receptor that is kinase-inactive (B82L-K721M) or C-terminally truncated (B82L-c'973) exhibit little PDGF-stimulated migration. In addition, none of these three cell lines exhibit the capacity to migrate to fibronectin alone. These observations indicate that, similar to cell migration toward fibronectin, PDGF-induced cell migration of B82L fibroblasts is augmented by the expression of an intact EGF receptor kinase. The loss of PDGF-stimulated motility in B82L cells that do not express an intact EGF receptor does not appear to result from a gross dysfunction of PDGF receptors, because ligand-stimulated tyrosine phosphorylation of the PDGF-beta receptor and the activation of mitogen-activated protein kinases are readily detectable in these cells. Moreover, an interaction between EGF and PDGF receptor systems is supported by the observation that the EGF receptor exhibits an increase in phosphotyrosine content in a time-dependent fashion upon the addition of PDGF. Altogether, these studies demonstrate that the expression of EGF receptor is critical for PDGF-stimulated migration of murine B82L fibroblasts and suggest a role for the EGF receptor downstream of PDGF receptor activation in the signaling events that lead to PDGF-stimulated cell motility.

Pituitary apoplexy in a patient with acute myeloid leukemia and thrombocytopenia.

We describe a 72-year-old woman with a history of acute myeloid leukemia who developed pituitary apoplexy associated with thrombocytopenia secondary to chemotherapy. She presented with new onset severe headache, nausea, vomiting and blurred vision. Initial physical examination was unremarkable. CT scan of the head was initially negative. Upon admission for further work up, She developed a high-grade fever, hypotension and obtundation. Subsequent physical examination revealed bitemporal visual fields defects and decreased visual acuity. Repeat imaging of head revealed a hemorrhagic pituitary mass compressing the optic chiasm. Laboratory results were compatible with the diagnosis of pan-hypopituitary syndrome. She received high dose steroids and was transferred for transnasal sphenoidotomy decompression surgery. The visual defects improved postoperatively. A literature review of Pituitary apoplexy is presented. Pituitary apoplexy secondary to thrombocytopenia has never been reported.