P744 The main influencing factors of cardiac adaptation effecting the diastolic and right ventricular function in peripubertic athletes

Introduction

Several studies examined the effects of regular training in peripubertic athletes’ heart, focusing on the left ventricle (LV). Their normal LV values are showing significant differences from adult athletes. In contrast, there are no specific normal ranges of the diastolic function and the right ventricular (RV) parameters in this age group. Moreover, the results of the latest studies are inconsistent through the different inclusion criteria and influencing factors.

Purpose, methods: The purpose of our study was to examine the specific diastolic and RV parameters of peripubertic athletes and compare them to the available normal values of adult athletes or healthy age-matched non-athletes. Furthermore, we were looking for the effects of the main influencing factors [lean body mass (LBM), body surface area (BSA), age, gender, training time, sporting discipline] on the echocardiographic parameters. 146 children and young adults (athletes, triathletes, basketball players, soccer players) were included between the age of 9 and 20 years (119 males, 27 females, 16,1 ±2,55 years). Specific 2D and tissue Doppler echocardiographic examinations were performed with one-lead continuous ECG gating.

Results

Examining the LV we did not find any significant differences comparing to the latest normal LV values by age. Significant positive correlation was found between the LV parameters, age and LBM. In comparison to adult athletes’ diastolic parameters, significantly (p< 0,001) higher E, lower A values and higher E/A ratio was detected. However, we found significantly (p< 0,001) higher lateral, septal and average e’ values and significantly (p< 0,001) lower E/e’ ratio compared to both reference groups. Therefore, the supernormal diastolic values of our athletes exceeded not only the diastolic performance of the age-matched non-athletes but also the adult professionals. Moreover, significantly (p< 0,001) lower structural and functional RV parameters were detected in the young athletes than the adult ones. In comparison to the peripubertic non-athletes significantly (p< 0,001) higher structural parameters, higher tricuspid S wave, RV end-diastolic and end-systolic area values were found. Contrary, there was no differences between the tricuspid annular plan excursion (TAPSE) values. Based on multivariate analysis we found remarkable correlation (r= 0,527, p< 0,001) between the diastolic or RV parameters and the common effect of the main influencing factors: LBM, BSA, age and training time.

Conclusion

There are no clearly defined normal values of diastolic and RV parameters in peripubertic athletes, however we also detected remarkable left and right ventricular changes in this young age group. Well-defined cut-off values should be applied to differentiate pathological conditions. The main influencing factors of the echocardiographic parameters are LBM, BSA, age and training time having additive effects on the cardiac adaptation.

Examination of the interaction of different lighting conditions and chronic mild stress in animal model

We examined the effects of different shift work schedules and chronic mild stress (CMS) on mood using animal model. The most common international shift work schedules in nursing were applied by three groups of Wistar-rats and a control group with normal light-dark cycle. One subgroup from each group was subjected to CMS. Levels of anxiety and emotional life were evaluated in light-dark box. Differences between the groups according to independent and dependent variables were examined with one- and two-way analysis of variance, with a significance level defined at p < 0.05. Interaction of lighting regimen and CMS was proved to be significant according to time spent in the light compartment and the average number of changes between the light and dark compartments. Results of our examination confirm that the changes of lighting conditions evocate anxiety more prominently than CMS. No significant differences were found between the results of the low rotating group and the control group, supposing that this schedule is the least harmful to health. Our results on the association between the use of lighting regimens and the level of CMS provide evidence that the fast rotating shift work schedule puts the heaviest load on the organism of animals.

Estimation of Risk of Recurrence of Early Stage Estrogen Receptor Positive Breast Carcinoma by Surgical and Medical Oncologists and Pathologists Compared to the Oncotype Dx® Recurrence Score

Background: The decision to use adjuvant chemotherapy in patients with early stage breast cancer is based in part on the estimation of risk of tumor recurrence by physicians, which traditionally relies heavily on tumor size, nodal status and a set of biologic tumor characteristics such as hormone receptor and HER2 expression. The Oncotype DX® assay is a 21-gene expression profile aiming to improve risk stratification, recurrence prediction and optimize selection of patients for adjuvant chemotherapy.Methods: We selected 154 consecutive patients with early stage estrogen receptor (ER) positive breast cancer and available Oncotype Dx® recurrence score (RS) for the study. Clinicopathologic data, including patient age, menopausal status, tumor size, histologic type, grade, mitotic activity, presence of lymphatic invasion (LVI), nodal status, hormone receptor and HER2 status on all patients were provided to four surgical oncologists, four medical oncologists and three pathologists, specializing in breast cancer diagnosis and management. Participants were asked to estimate the risk of recurrence of tumors based on available clinicopathologic data and to provide the three most important tumor features their risk estimates were based on. Risk estimates of participants were compared with RS results.Results: Based on the Oncotype Dx® results, 95 (61.7%), 45 (29.2%) and 14 (9.1%) tumors were of low (RS &lt;18), intermediate (RS 18-30) and high (RS ≥31) risk, respectively. RS values showed a highly significant correlation with tumor grade, mitotic activity, LVI, hormone receptor and HER2 status, while no correlation with patient age, menopausal status, tumor size and histologic type was found. Participants' risk estimates agreed with those of the Oncotype Dx® assay in 54.2 ± 2.3 % (mean ± SEM, range 41.6 - 63.0%) of cases, while the risk of recurrence was over- and underestimated compared to RS results in 31.8 ± 3.1% (16.2 - 43.5%) and 14.1 ± 1.4% (7.1 - 22.7%), respectively. The rates of overestimation were significantly higher than those of underestimation (p = 0.0003). Although medical oncologists tended to overestimate the risk more frequently (38.1 ± 2.0%) compared to surgeons (28.7 ± 5.9%) and pathologists (27.5 ± 7.8%), the difference did not reach statistical significance. Estimation of the agreement of participants' risk assessment with RS results showed a mean kappa value of 0.2955 (range 0.1506 - 0.4123). No statistically significant difference in overall concurrence with RS results was found between surgeons, medical oncologists and pathologists. Participants ranked tumor stage/nodal status, hormone receptor status and tumor size to be the most important features when estimating recurrence risk.Conclusions: Based on traditional clinicopathologic features alone, surgeons, medical oncologists and pathologists tend to overestimate the risk of tumor recurrence as compared to Oncotype Dx® assay results. The RS may provide additional information regarding the intrinsic biological features of ER positive breast cancers and help tailoring treatment recommendations.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 4061.

The Effect of Oncotype Dx® Recurrence Score on Treatment Recommendations for Patients with Early Stage Estrogen Receptor Positive Breast Cancer

Background: Current guidelines recommend administration of chemotherapy for patients with breast carcinomas &gt;1 cm in size, with consideration for patient age, comorbidities and tumor grade. However, it is unknown which patients actually benefit from therapy and overtreatment of a significant proportion of patients is a major concern. We investigated the impact of the Oncotype Dx® Recurrence Score (RS) on chemotherapy recommendations in early stage estrogen receptor (ER) positive breast cancer patients.Methods: We selected 154 patients with early stage ER positive breast cancer and available RS for the study. Clinicopathologic data, including age, menopausal status, tumor size, type, grade, mitotic activity, presence of lymphatic invasion, nodal status, hormone receptor and HER2 status on all patients were provided to four surgical oncologists, four medical oncologists and three pathologists, specializing in breast cancer diagnosis and management. Assuming that all patients were in good general health and would receive endocrine therapy, participants were asked whether they would also advovate adjuvant chemotherapy based on clinicopathologic data with and without knowledge of the RS, and to provide the three salient clinicopathologic features on which their recommendations were based. Changes in recommendations of participants following inclusion of RS data were compared.Results: Based on RS results, 95 (61.7%), 45 (29.2%) and 14 (9.1%) tumors were of low (RS &lt;18), intermediate (RS 18-30) and high (RS ≥31) risk, respectively. The results are summarized in Table 1. Assuming that the hypothesis previously put forward that patients with low to intermediate risk RS are not likely to benefit from chemotherapy, 82.3 ± 1.3% (75.5 - 89.0%) and 69.0 ± 6.9% (5.9 - 85.7%) of patients for whom chemotherapy was recommended by the participants would be "overtreated" without and with the use of RS results (p = 0.0322). No statistically significant difference was found among surgeons, medical oncologists and pathologists. Participants ranked patient age/menopausal status, hormone receptor status and tumor stage/nodal status to be the most important features when recommending chemotherapy.Conclusions: Although current recommendations for adjuvant chemotherapy for early stage ER positive breast cancer patients are largely in line with published guidelines, inclusion of RS alters recommendations in about 25% of cases. While medical oncologists recommended chemotherapy more frequently compared to surgeons and pathologists, they were more likely to change recommendations in light of RS results.Table 1. Summary of results SurgeonsMedical oncologistsPathologistsp* Mean ± SEMRangeMean ± SEMRangeMean ± SEMRange Chemo without RS (%)29.2 ± 1.824.0 - 31.859.0 ± 5.046.8 - 70.846.8 ± 3.741.6 - 53.90.0156Chemo with RS (%)27.0 ± 5.611.0 - 36.438.6 ± 9.517.5 - 63.644.4 ± 5.833.8 - 53.90.1794No change (%)75.3 ± 7.054.5 - 85.766.7 ± 6.851.3 - 83.885.9 ± 6.478.6 - 98.70.3682Add chemo (%)11.2 ± 4.13.2 - 22.76.5 ± 1.93.2 - 11.75.8 ± 3.20.6 - 11.70.6882Avoid chemo (%)13.5 ± 3.94.5 - 22.726.8 ± 7.94.5 - 41.68.2 ± 4.50.6 - 16.20.2186*Kruskal-Wallis test

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 4058.

Opposite roles of protein kinase C isoforms in proliferation, differentiation, apoptosis, and tumorigenicity of human HaCaT keratinocytes

We have previously shown that the protein kinase C (PKC) system plays a pivotal role in regulation of proliferation and differentiation of the human keratinocyte line HaCaT which is often used to assess processes of immortalization, transformation, and tumorigenesis in human skin. In this paper, using pharmacological and molecular biology approaches, we investigated the isoform-specific roles of certain PKC isoenzymes (conventional cPKCalpha and beta; novel nPKCdelta and epsilon) in the regulation of various keratinocyte functions. cPKCalpha and nPKCdelta stimulated cellular differentiation and increased susceptibility of cells to actions of inducers of apoptosis, and they markedly inhibited cellular proliferation and tumor growth in immunodeficient mice. In marked contrast, cPKCbeta and nPKCepsilon increased both in vitro and in vivo growth of cells and inhibited differentiation and apoptosis. Our data present clear evidence for the specific, antagonistic roles of certain cPKC and nPKC isoforms in regulating the above processes in human HaCaT keratinocytes.

Prominent stress response of Purkinje cells in Creutzfeldt-Jakob disease

To examine the role of stress-related 70-kDa heat shock proteins (Hsp-s) in Creutzfeldt-Jakob disease (CJD), we performed immunocytochemistry to detect Hsp-72 and Hsp-73, together with the abnormal (PrP(Sc)) and the presumed cellular form (PrP(C)) of the prion protein, and TUNEL method to measure cellular vulnerability in different brain regions in CJD and control cases. While Hsp-73 showed uniform distribution in all the examined samples, an increase in the number of Purkinje cells with prominent accumulation of Hsp-72 in the CJD group was observed. These neurons also showed intense PrP(C) staining, but TUNEL-positive nuclei were only detected in the granular (Hsp-72-negative) cell layer. Fewer cells of the inferior olivary nucleus were immunoreactive for Hsp-72 in CJD than in control cases, and regions showing severe spongiform change and gliosis exhibited fewer Hsp-72-immunoreactive neurons. Our results indicate that accumulation of the inducible Hsp-72 in certain cell types may be part of a cytoprotective mechanism, which includes preservation of proteins like PrP(C).

Erythropoietin and erythropoietin receptor expression in human cancer

Erythropoietin (EPO) stimulates the growth of erythroblasts in the bone marrow (C. Lacombe and P. Mayeux, NEPHROL: DIAL: TRANSPLANT:, 14 (SUPPL: 2): 22-28, 1999). We report basal and hypoxia-stimulated expression of EPO and its receptor, EPOR, in human breast cancer cells, and we demonstrate EPO-stimulated tyrosine phosphorylation and the proliferation of these cells in vitro. In 50 clinical specimens of breast carcinoma, we report high levels of EPO and EPOR associated with malignant cells and tumor vasculature but not with normal breast, benign papilloma, or fibrocystic tissue. Hypoxic tumor regions display the highest levels of EPO and EPOR expression. Enhanced EPO signaling may contribute to the promotion of human cancer by tissue hypoxia.

[Protein kinase C as a potential target for drug development in cancer research]

The central role of protein kinase C (PKC) in cellular signaling makes it an attractive and promising target for drug development. With increasing insight into the regulation by ligands, by phosphorylation, and by macromolecular interactions involved in localization, we will be able to predict the consequences of modifications in second messenger levels resulting from changes in oncogenes, growth factors, or the exposures to xenobiotics. The multiplicity of functionally distinct isoforms of PKC and the depth of modification of their properties in a cell-context specific fashion provide abundant opportunities for generating therapeutic specificity. The emerging elucidation of the complexities of regulation of PKC folding and localization presents the opportunity to pursue novel strategies for intervention, complementing the efforts directed at the design of selective catalytic site inhibitors. Although PKC initially attracted the attention of cancer researchers as a potential therapeutic target, its general role in signal transduction affords a much broader field of opportunity.

Effect of a tyrosine 155 to phenylalanine mutation of protein kinase cdelta on the proliferative and tumorigenic properties of NIH 3T3 fibroblasts

Tyrosine phosphorylation has emerged as an important mechanism in the regulation of enzyme function. In this paper, we describe a mutant of PKCdelta altered at a single tyrosine residue which has the opposite effect compared with wild-type PKCdelta on the growth characteristics of NIH 3T3 cells. Overexpression of wild-type PKCdelta results in a decreased growth rate and a lower cell density at confluency. On the other hand, overexpression of PKCdelta with a mutation from tyrosine to phenylalanine at position 155 results in a significantly higher rate of growth and a higher density at confluency compared with vector controls. Moreover, these cells are able to grow in soft agar and to form tumors in nude mice. In contrast to kinase negative PKC constructs, this mutant maintains in vitro kinase activity and shows a subcellular localization and a translocation pattern that are similar to those of the wild-type PKCdelta. Whether the altered biological effect is due to the missing phosphorylation on tyrosine or the mutation from tyrosine to phenylalanine per se remains under investigation.

Comparison of the roles of the C1a and C1b domains of protein kinase C alpha in ligand induced translocation in NIH 3T3 cells

To explore the relative roles of the two C1 domains of protein kinase C alpha (PKC alpha) in the response to phorbol esters and related analogs, we mutated the individual C1 domains, expressed the mutated PKC alpha in NIH 3T3 cells, and then examined the ability of ligands to induce its translocation to the membrane. The C1a and C1b domains play equivalent roles for translocation in response to phorbol 12-myristate 13-acetate, mezerein, and (-)octylindolactam V. These results contrast with those previously reported for PKC delta, suggesting that the domains play different roles in different PKC isoforms.

Regulation of actin cytoskeleton in lymphocytes: PKC-delta disrupts IL-3-induced membrane ruffles downstream of Rac1

In the murine pre-B lymphoid cell line Baf3, the presence of IL-3 is required for the formation of membrane ruffles that intensely stain for actin and are responsible for the elongated cell phenotype. Withdrawal of IL-3 dissolves ruffled protrusions and converts the cell phenotype to round. Flow cytometric analysis of the cell shape showed that an inactive analog of Rac1 but not inactive RhoA or inactive cdc42 rounds the cells in the presence of IL-3. Constitutively activated Rac1 restores the elongated cell phenotype to IL-3-starved cells. We conclude that the activity of Rac1 is necessary and sufficient for the IL-3-induced assembly of membrane ruffles. Similar to the IL-3 withdrawal, phorbol 12-myristate 13-acetate (PMA) dissolves actin-formed membrane ruffles and rounds the cells in the presence of IL-3. Flow cytometric analysis of the cell shape demonstrated that in the presence of IL-3 the PMA-induced cell rounding cannot be abolished by constitutively active Rac1 but can be imitated by inactive Rac1. These data indicate that PMA disrupts the IL-3 pathway downstream of Rac1. Cells rounded by PMA return to the elongated phenotype concomitantly with PKC depletion. PMA-induced cell rounding can be reversed by the PKC-specific inhibitor GF109203X. Experiments with overexpression in Baf3 of individual PKC isoforms and a dominant negative PKC-delta indicate that activation of PKC-delta but not other PKC isoforms is responsible for disruption of membrane ruffles.

Protein kinase C-epsilon plays a role in neurite outgrowth in response to epidermal growth factor and nerve growth factor in PC12 cells

In this study, we examined the role of specific protein kinase C (PKC) isoforms in the differentiation of PC12 cells in response to nerve growth factor (NGF) and epidermal growth factor (EGF). PC12 cells express PKC-alpha, -beta, -gamma, -delta, -epsilon, -mu, and -zeta. For PKC-delta, -epsilon, and -zeta, NGF and EGF exerted differential effects on translocation. Unlike overexpression of PKC-alpha and -delta, overexpression of PKC-epsilon caused enhanced neurite outgrowth in response to NGF. In the PKC-epsilon-overexpressing cells, EGF also dramatically induced neurite outgrowth, arrested cell proliferation, and induced a sustained phosphorylation of mitogen-activated protein kinase (MAPK), in contrast to its mitogenic effects on control cells or cells overexpressing PKC-alpha and -delta. The induction of neurite outgrowth by EGF was inhibited by the MAPK kinase inhibitor PD95098. In cells overexpressing a PKC-epsilon dominant negative mutant, NGF induced reduced neurite outgrowth and a more transient phosphorylation of MAPK than in controls. Our results suggest an important role for PKC-epsilon in neurite outgrowth in PC12 cells, probably via activation of the MAPK pathway.

Protein kinase C delta (PKCdelta) inhibits the expression of glutamine synthetase in glial cells via the PKCdelta regulatory domain and its tyrosine phosphorylation

Protein kinase C (PKC) plays an important role in the proliferation and differentiation of glial cells. In a recent study we found that overexpression of PKCdelta reduced the expression of the astrocytic marker glutamine synthetase (GS). In this study we explored the mechanisms involved in the inhibitory effect of PKCdelta on the expression of glutamine synthetase. Using PKC chimeras we first examined the role of the catalytic and regulatory domains of PKCdelta on the expression of glutamine synthetase. We found that cells stably transfected with chimeras between the regulatory domain of PKCdelta and the catalytic domains of PKCalpha or epsilon inhibited the expression of GS, similar to the inhibition exerted by overexpression of PKCdelta itself. In contrast, no significant effects were observed in cells transfected with the reciprocal PKC chimeras between the regulatory domains of PKCalpha or epsilon and the catalytic domain of PKCdelta. PKCdelta has been shown to undergo tyrosine phosphorylation in response to various activators. Tyrosine phosphorylation of PKCdelta in response to phorbol 12-myristate 13-acetate and platelet-derived growth factor occurred only in chimeras which contained the PKCdelta regulatory domain. Cells transfected with a PKCdelta mutant (PKCdelta5), in which the five putative tyrosine phosphorylation sites were mutated to phenylalanine, showed markedly diminished tyrosine phosphorylation in response to phorbol 12-myristate 13-acetate and platelet-derived growth factor and normal levels of GS. Our results indicate that the regulatory domain of PKCdelta mediates the inhibitory effect of this isoform on the expression of GS. Phosphorylation of PKCdelta on tyrosine residues in the regulatory domain is implicated in this inhibitory effect.

Differential role of specific PKC isoforms in the proliferation of glial cells and the expression of the astrocytic markers GFAP and glutamine synthetase

In this study, we explored the role of specific protein kinase C (PKC) isoforms in glial cell proliferation and on the expression of the astrocytic markers GFAP and glutamine synthetase using C6 cells as a model. Analysis of the expression of the various PKC isoforms in control and differentiated C6 cells revealed differences in the expression of specific PKC isoforms. Undifferentiated C6 cells, which express low levels of GFAP and glutamine synthetase (GS), have high levels of PKCalpha and delta, whereas differentiated C6 cells, which express higher levels of both GFAP and GS have lower levels of PKCalpha and delta and higher levels of PKCgamma, theta and eta. Using C6 cells overexpressing specific PKC isoforms, we examined the role of these isoforms on the proliferation and differentiation of C6 cells. Cells overexpressing PKCalpha displayed a reduced level of GFAP, whereas GS expression was not affected. On the other hand, cells overexpressing PKCdelta showed reduced GS expression but little effect on GFAP. Finally, cells expressing PKCgamma displayed a marked increase in the levels of both GFAP and GS. The proliferation of C6 cells was increased in cells overexpressing PKCalpha and epsilon and decreased in cells overexpressing PKCgamma, delta and eta. The results of this study suggest that glial cell proliferation and astrocytic differentiation can be regulated by specific PKC isoforms that selectively affect cell proliferation and the expression of the two astrocytic markers GFAP and GS.

Specific vanilloid responses in C6 rat glioma cells

Capsaicin and its ultrapotent analog resiniferatoxin (RTX) act through specific vanilloid receptors on sensory neurons. Here, we describe specific vanilloid responses in rat C6 glioma cells. Capsaicin and RTX stimulated 45Ca uptake in a similar fashion to that found for cultured rat dorsal root ganglion neurons (DRGs); this response was antagonized by the antagonists capsazepine and ruthenium red. As in DRGs, pretreatment of C6 cells with capsaicin or RTX produced desensitization to subsequent stimulation of 45Ca uptake. The potency for desensitization by RTX in the C6 cells corresponded to that for 45Ca uptake, whereas in DRGs it occurred at significantly lower concentrations corresponding to that for the high affinity [3H]RTX binding site. Consistent with this difference, in C6 cells we were unable to detect [3H]RTX binding. These characteristics suggest the presence of C-type but not R-type vanilloid receptors on C6 cells. After 2 day treatment, capsaicin but not RTX inhibited the proliferation and altered the differentiation of the cells and produced apoptosis. In the long term experiments, capsazepine, instead of antagonizing the effect of capsaicin, acted as an agonist. Moreover, capsazepine displayed these effects with higher potency than that of capsaicin. The different potencies and structure activity relations suggest a distinct mechanism for these long-term vanilloid effects. Our finding that C6 cells can respond directly to capsaicin necessitates a reevaluation of the in vivo pathway of response to vanilloids, and highlights the importance of the neuron-glial network.

Differential selectivity of ligands for the C1a and C1b phorbol ester binding domains of protein kinase Cdelta: possible correlation with tumor-promoting activity

Protein kinase C (PKC) represents the major, high-affinity receptor for the phorbol esters as well as for a series of structurally diverse natural products. The phorbol esters function by binding to the tandem C1a and C1b domains in PKC, leading to enzyme activation. Although the typical phorbol esters represent the paradigm for tumor promoters in mouse skin, it is now clear that different high affinity ligands for PKC have distinct biological effects. Thus, the daphnane analogue mezerein is a second-stage promoter, the macrolide bryostatin 1 is a partial antagonist, and certain 12-deoxyphorbol 13-monoesters also function as partial antagonists but with a different pattern of activity. The biochemical basis for these differences is an area of active investigation. In this report, we have examined the relative interaction of ligands differing in structure and pattern of biological response with the C1a and C1b domains of PKCdelta. We mutated either or both of the C1 domains of PKCdelta, expressed the constructs in NIH 3T3 cells, and monitored the interaction of the ligands by their ability to induce translocation of the mutated PKCdelta from the cytosol to the particulate fraction. We found that different ligands showed different dependence on the C1a and C1b domains for translocation. Whereas phorbol 12-myristate 13-acetate and the indole alkaloids indolactam and octylindolactam were selectively dependent on the C1b domain, selectivity was not observed for mezerein, for the 12-deoxyphorbol 13-monoesters prostratin or 12-deoxyphorbol 13-phenylacetate, or for the macrocyclic lactone bryostatin 1. Provocatively, the pattern of response corresponds with the activity of the compounds as complete tumor promoters.

Characterization of functional vanilloid receptors expressed by mast cells

Capsaicin and its ultrapotent analog resiniferatoxin (RTX) act through specific vanilloid receptors on sensory neurons. The C-type receptor is coupled to 45Ca uptake, whereas the R-type is detectable by [3H]RTX binding. We describe here specific vanilloid responses in murine mast cells (MCs). In the MC lines and in bone marrow-derived mast cells, capsaicin and RTX induced 45Ca uptake similarly to that observed for cultured rat dorsal root ganglion neurons (DRGs). This response was antagonized by the antagonists capsazepine and ruthenium red. As in DRGs, pretreatment of MCs with capsaicin or RTX induced desensitization to subsequent stimulation of 45Ca uptake. The potency for desensitization by RTX in the MCs corresponded to that for 45Ca uptake, whereas in DRGs it occurred at significantly lower concentrations corresponding to that for the high-affinity [3H]RTX binding site. Consistent with this difference, in MCs we were unable to detect [3H]RTX binding. Vanilloids were noncytotoxic to the MCs, in contrast to the DRGs. Although vanilloids did not cause degranulation in MCs, in the P815 clone capsaicin evoked selective interleukin-4 release. We conclude that certain MCs possess vanilloid receptors, but only the C-type that functions as a channel. Our finding that MCs can respond directly to capsaicin necessitates a reevaluation of the in vivo pathway of inflammation in response to vanilloids.

The catalytic domain of PKC-epsilon, in reciprocal PKC-delta and -epsilon chimeras, is responsible for conferring tumorgenicity to NIH3T3 cells, whereas both regulatory and catalytic domains of PKC-epsilon contribute to in vitro transformation

Protein kinase C-epsilon (PKC-epsilon) has been shown to increase growth and cause malignant transformation when overexpressed in NIH3T3 cells, whereas PKC-delta reduced fibroblast growth. Two reciprocal chimeric proteins (PKC-epsilondelta and PKC-deltaepsilon were constructed by exchanging the regulatory and catalytic domains of PKC-delta and -epsilon and were stably overexpressed in NIH3T3 cells. Fibroblasts that overexpressed either chimera showed maximum cell density and morphology that were intermediate between cells overexpressing PKC-delta and those that overexpressed PKC-epsilon. Moreover, all lines that expressed chimeras were capable of anchorage-independent growth in the presence of TPA, which indicated that both the regulatory and catalytic domains of PKC-epsilon could independently induce NIH3T3 transformation, although the combination of both domains, as found in PKC-epsilon, was the most active form. In contrast, the translocation pattern and ability to induce tumors in nude mice was attributable to the catalytic domains exclusively. In particular, cells that expressed PKC-deltaepsilon retained PKC-epsilon's full potency of tumorgenicity when injected into nude mice. In sum, our findings not only reinforce the concept that only certain PKC isozymes contribute to carcinogenesis but also show that different domains of PKCs mediate the physiologically distinguishable events of transformation and tumorgenesis.

The catalytic domain of protein kinase Cdelta confers protection from down-regulation induced by bryostatin 1

Bryostatin 1 (Bryo) has been shown to induce biphasic dose-response curves for down-regulating protein kinase Cdelta (PKCdelta) as well as for protecting PKCdelta from down-regulation induced by phorbol 12-myristate 13-acetate (PMA). To identify regions within PKCdelta that confer these responses to Bryo, we utilized reciprocal PKCalpha and PKCdelta chimeras (PKCalpha/delta and PKCdelta/alpha) constructed by exchanging the regulatory and catalytic domains of these PKCs. These chimeras and wild-type PKCalpha/alpha and PKCdelta/delta constructed in the same way were stably expressed in NIH 3T3 fibroblasts. Twenty-four h of treatment with Bryo induced a biphasic dose-response curve for down-regulating both wild-type PKCdelta/delta and the PKCalpha/delta chimera. In contrast, Bryo led to a nearly complete down-regulation of both PKCalpha/alpha and PKCdelta/alpha and also produced a faster mobility form of these species on SDS-polyacrylamide gel electrophoresis. The nature of both the regulatory and, to a lesser extent, the catalytic domains affected the potency of Bryo to down-regulate the chimeric PKC proteins as well as to protect PKCalpha/delta and PKCdelta/delta from down-regulation. Bryo at high concentrations also inhibited the down-regulation of PKCdelta/delta and PKCalpha/delta induced by 1 microM PMA when co-applied. The portion of PKC protected by Bryo from down-regulation by either Bryo or PMA was localized in the particulate fraction of the cells. We conclude that the catalytic domain of PKCdelta confers protection from down-regulation induced by Bryo or Bryo plus PMA, suggesting that this domain contains the isotype-specific determinants involved in the unique effect of Bryo on PKCdelta.

Both the catalytic and regulatory domains of protein kinase C chimeras modulate the proliferative properties of NIH 3T3 cells

Protein kinase C (PKC) isozymes exhibit important differences in terms of their regulation and biological functions. Not only may some PKC isoforms be active and others not for a given response, but the actions of different isoforms may even be antagonistic. In NIH 3T3 cells, for example, PKCdelta arrests cell growth whereas PKCepsilon stimulates it. To probe the contribution of the regulatory and the catalytic domains of PKC isozymes to isozyme-specific responses, we prepared chimeras between the regulatory and the catalytic domains of PKCalpha, -delta, and -epsilon. These chimeras, which preserve the overall structure of the native PKC enzymes, were stably expressed in mouse fibroblasts. A major objective was to characterize the growth properties of the cells that overexpress the various PKC constructs. Our data demonstrate that both the regulatory and the catalytic domains play roles in cell proliferation. The regulatory domain of PKCepsilon enhanced cell growth in the absence or presence of phorbol 12-myristate 13-acetate (PMA), and, in the presence of PMA, all chimeras with the PKCepsilon regulatory domain also gave rise to colonies in soft agar; the role of the catalytic domain of PKCepsilon was evident in the PMA-treated cells that overexpressed the PKC chimera containing the delta regulatory and the epsilon catalytic domains (PKCdelta/epsilon). The important contribution of the PKCepsilon catalytic domain to the growth of PKCdelta/epsilon-expressing cells was also evident in terms of a significantly increased saturation density in the presence of PMA, their formation of foci upon PMA treatment, and the induction of anchorage-independent growth. Aside from the growth-promoting effect of PKCepsilon, we have shown that most chimeras with PKCalpha and -delta regulatory domains inhibit cell growth. These results underscore the complex contributions of the regulatory and catalytic domains to the overall behavior of PKC.

Functional effects of overexpression of protein kinase C-alpha, -beta, -delta, -epsilon, and -eta in the mast cell line RBL-2H3

The rat basophilic leukemic (RBL-2H3) cell line was stably transfected with the endogenously expressed Ca2+-dependent protein kinase C-alpha (PKC-alpha) and -betaI and the Ca2+-independent delta and epsilon isoforms to study their functional roles. In addition, the Ca2+-independent PKC-eta was expressed. All transfected PKC isoforms translocated to the membrane-containing fraction in response to aggregation of the IgE-sensitized high affinity receptor for IgE (Fc epsilonRI) with the Ag dinitrophenyl(25)-BSA. All PKC transfectants, except PKC-eta, showed increased proliferative responses, and aggregation of Fc epsilonRI further enhanced the rate of proliferation. The PKC transfectants also showed increased phosphoinositide hydrolysis in response to Ag aggregation of receptors. No marked differences in the Ca2+ responses of the transfectants to Ag or thapsigargin were observed. Overexpression of PKC-alpha or -epsilon specifically inhibited receptor-dependent cytosolic phospholipase A2 (cPLA2) activity, whereas this activity was enhanced in the PKC-betaI transfectant. Analysis of the secretory response revealed that overexpression of PKC-betaI and -eta significantly enhanced secretion. A broad spectrum of cytokine mRNAs was detected in all transfectants, and overexpression of PKC-betaI significantly enhanced the receptor-dependent production of IL-2 and IL-6 mRNA. These studies identify PKC-alpha and -epsilon as negative regulators of cPLA2 activity and demonstrate the importance of PKC-beta as a positive modulator of secretion, cPLA2 activity, and cytokine production in this mast cell line.

Functional effects of overexpression of protein kinase C-alpha, -beta, -delta, -epsilon, and -eta in the mast cell line RBL-2H3

The rat basophilic leukemic (RBL-2H3) cell line was stably transfected with the endogenously expressed Ca2+-dependent protein kinase C-alpha (PKC-alpha) and -betaI and the Ca2+-independent delta and epsilon isoforms to study their functional roles. In addition, the Ca2+-independent PKC-eta was expressed. All transfected PKC isoforms translocated to the membrane-containing fraction in response to aggregation of the IgE-sensitized high affinity receptor for IgE (Fc epsilonRI) with the Ag dinitrophenyl(25)-BSA. All PKC transfectants, except PKC-eta, showed increased proliferative responses, and aggregation of Fc epsilonRI further enhanced the rate of proliferation. The PKC transfectants also showed increased phosphoinositide hydrolysis in response to Ag aggregation of receptors. No marked differences in the Ca2+ responses of the transfectants to Ag or thapsigargin were observed. Overexpression of PKC-alpha or -epsilon specifically inhibited receptor-dependent cytosolic phospholipase A2 (cPLA2) activity, whereas this activity was enhanced in the PKC-betaI transfectant. Analysis of the secretory response revealed that overexpression of PKC-betaI and -eta significantly enhanced secretion. A broad spectrum of cytokine mRNAs was detected in all transfectants, and overexpression of PKC-betaI significantly enhanced the receptor-dependent production of IL-2 and IL-6 mRNA. These studies identify PKC-alpha and -epsilon as negative regulators of cPLA2 activity and demonstrate the importance of PKC-beta as a positive modulator of secretion, cPLA2 activity, and cytokine production in this mast cell line.

The catalytic domain of protein kinase C chimeras modulates the affinity and targeting of phorbol ester-induced translocation

Emerging evidence suggests important differences among protein kinase C (PKC) isozymes in terms of their regulation and biological functions. PKC is regulated by multiple interdependent mechanisms, including enzymatic activation, translocation of the enzyme in response to activation, phosphorylation, and proteolysis. As part of our ongoing studies to define the factors contributing to the specificity of PKC isozymes, we prepared chimeras between the catalytic and regulatory domains of PKCalpha, -delta, and -epsilon. These chimeras, which preserve the overall structure of the native PKC enzymes, were stably expressed in NIH 3T3 fibroblasts. Their intracellular distribution was similar to that of the endogenous enzymes, and they responded with translocation upon treatment with phorbol 12-myristate 13-acetate (PMA). We found that the potency of PMA for translocation of the PKCalpha/x chimeras from the soluble fraction was influenced by the catalytic domain. The ED50 for translocation of PKCalpha/alpha was 26 nM, in marked contrast to the ED50 of 0.9 nM in the case of the PKCalpha/epsilon chimera. In addition to this increase in potency, the site of translocation was also changed; the PKCalpha/epsilon chimera translocated mainly into the cytoskeletal fraction. PKCx/epsilon chimeras displayed twin isoforms with different mobilities on Western blots. PMA treatment increased the proportion of the higher mobility isoform. The two PKCx/epsilon isoforms differed in their localization; moreover, their localization pattern depended on the regulatory domain. Our results emphasize the complex contributions of the regulatory and catalytic domains to the overall behavior of PKC.

Recent advances in understanding of vanilloid receptors: a therapeutic target for treatment of pain and inflammation in skin

C-fiber sensory afferent neurons, which contain neuropeptides such as calcitonin-gene related peptide and substance P, mediate a wide variety of physiologic responses, including chemogenic pain, thermoregulation, and neurogenic inflammation. Capsaicin, the pungent constituent in red pepper, functions to activate and then, at higher doses and longer times, desensitize this class of neurons. This latter response provides the basis for the therapeutic application of capsaicin. A major advance in the field has been the identification of resiniferatoxin, a phorbol-related diterpene, as an analog of capsaicin that is ultrapotent but with differential selectivity. In particular, resiniferatoxin is only similar in potency for induction of pain but is much more effective for desensitization. Structure-activity analysis in whole animal experiments provides further evidence for dissociation of biologic endpoints, strongly arguing for the existence of vanilloid receptor subclasses. Using resiniferatoxin, we have been able to define specific, high-affinity receptors for capsaicin both in animal models such as rats and in man. Of great importance, the pharmacologic characterization in cultured dorsal root ganglion cells of the high-affinity resiniferatoxin-binding site and of the physiologic response believed to be directly coupled to the receptor, viz. calcium uptake, differed in structure-activity and in cooperativity. We conclude that multiple high-affinity vanilloid receptor subclasses mediate vanilloid response; moreover, the resiniferatoxin-selective subclass of vanilloid receptors is not the voltage-independent, cation-nonselective ion channel as previously believed. Optimization of ligands for the individual vanilloid receptor subclasses should revolutionize this therapeutic area.

Differential activation and desensitization of sensory neurons by resiniferatoxin

Recently, with use of rat dorsal root ganglion (DRG) neurons we have been able to dissociate the binding affinities of vanilloids from their potencies to induce 45Ca uptake, which suggests the existence of distinct classes of the vanilloid receptor (). In the present study, we have demonstrated that the ultrapotent capsaicin analog resiniferatoxin (RTX) desensitized rat DRG neurons to the subsequent induction of 45Ca uptake by capsaicin and RTX with affinity and cooperativity similar to that found for [3H]RTX binding, contrasting with a approximately 10-fold weaker potency and lack of cooperativity to induce 45Ca uptake. Likewise, the competitive antagonist capsazepine inhibited RTX-induced desensitization with potency similar to that for inhibition of specific [3H]RTX binding, whereas the potency of capsazepine was approximately 10-fold higher for inhibiting RTX-induced 45Ca uptake. Finally, the noncompetitive antagonist ruthenium red inhibited both the RTX-induced desensitization and 45Ca uptake but showed approximately 60-fold selectivity for inhibiting RTX-induced desensitization. The RTX-induced desensitization was not associated with loss of specific [3H]RTX binding, suggesting lack of gross cell toxicity. In contrast to RTX, capsaicin caused desensitization with a potency corresponding to that for 45Ca uptake and did so in a noncooperative manner. Unlike the RTX-induced desensitization, the desensitization by capsaicin was blocked by ruthenium red only at doses that blocked 45Ca uptake and depended on external calcium. Our findings provide further support for the existence of vanilloid receptor subtypes on DRG neurons with distinct pharmacology and distinct patterns of desensitization.

Modeling, chemistry, and biology of the benzolactam analogues of indolactam V (ILV). 2. Identification of the binding site of the benzolactams in the CRD2 activator-binding domain of PKCdelta and discovery of an ILV analogue of improved isozyme selectivity

Protein kinase C (PKC) is a complex enzyme system comprised of at least 11 isozymes that serves to mediate numerous extracellular signals which generate lipid second messengers. The discovery of isozyme-selective activators and inhibitors (modulators) of PKC is crucial to ascertaining the role of the individual isozymes in physiological and pathophysiological processes and to manipulating their function. The discovery of such small molecule modulators of PKC is at present a largely unmet pharmacological need. Herein we detail our modeling studies which reveal how the natural product indolactam V (ILV) and its 8-membered ring analogue, the benzolactam 15, bind to the CRD2 activator domain of PKC. These modeling studies reveal that not all PKC ligands possess a common pharmacophore, and further suggest an important role of specific hydrophobic contacts in the PKC-ligand interaction. The modeling studies find strong experimental support from mutagenesis studies on PKC alpha that reveal the crucial role played by the residues proline 11, leucine 20, leucine 24, and glycine 27. Next, we describe the synthesis of two 8-substituted benzolactams starting from L-phenylalanine and characterize their isozyme selectivity; one of the two benzolactams exhibits improved isozyme selectivity relative to the n-octyl-ILV. Lastly, we report inhibition of cellular proliferation of two different breast carcinoma cell lines by the benzolactam 5 and show that the compound preferentially down-regulates PKCbeta in both cell lines.

The catalytic domain of protein kinase C-delta in reciprocal delta and epsilon chimeras mediates phorbol ester-induced macrophage differentiation of mouse promyelocytes

The overexpression of protein kinase C-delta (PKC-delta), but not PKC-epsilon, enables the mouse myeloid cell line 32D to differentiate into macrophages when treated with phorbol esters such as 12-O-tetradecanoylphorbol-13-acetate (TPA). To determine the domain of PKC-delta that is responsible for this isotype-specific function, cDNAs that encode reciprocal chimeras of PKC-delta and -epsilon (PKC-delta epsilon and PKC-epsilon delta) were constructed by exchanging regulatory and kinase domains using polymerase chain reaction technology. Both chimeras were stably expressed in 32D cells using the pLTR expression vector and displayed protein kinase activity upon TPA treatment. TPA treatment of L epsilon delta, cells that overexpressed the PKC-epsilon delta chimera, induced a dramatically increased cell volume, surface adherence, surface expression of Mac-1 and Mac-3, lysozyme production, and phagocytosis. These are the characteristics of the macrophage phenotype found in TPA-treated 32D cells that overexpressed PKC-delta. In contrast, little effect was seen in L delta epsilon, 32D cells that overexpressed PKC-delta epsilon, with or without TPA treatment. A PKC inhibitor directed toward the catalytic domain of PKC, GF109203X, and a selective inhibitor of PKC-delta, Rottlerin, blocked the TPA-induced differentiation of PKC-epsilon delta-overexpressing 32D cells. These results demonstrate that the catalytic domain of PKC-delta contains the primary determinants for its activity in phorbol ester-induced macrophage differentiation.

Conformationally constrained analogues of diacylglycerol. 13. Protein kinase C ligands based on templates derived from 2,3-dideoxy-L-erythro(threo)-hexono-1,4-lactone and 2-deoxyapiolactone

In the present investigation, the last two possible modes of generating conformationally semirigid diacylglycerol (DAG) analogues embedded into five-membered ring lactones as templates III and IV are investigated. The first two templates studied in previous investigations corresponded to 2-deoxyribonolactone (template I) and 4,4-disubstituted gamma-butyrolactone (template II), with the latter producing potent protein kinase C (PK-C) ligands with low nanomolar binding affinities. The templates reported in this work correspond to 2,3-dideoxy-L-erythro- or -threo-hexono-1,4-lactone (template III) and 2-deoxyapiolactone (template IV). Compounds constructed with the dideoxy-L-erythro- or -threo-hexono-1,4-lactone template were synthesized stereospecifically from tri-O-acetyl-L-glucal and L-galactono-1,4-lactone, respectively. Compounds constructed with the 2-deoxyapiolactone template were synthesized stereoselectively from di-O-isopropylidene-alpha-D-apiose. Inhibition of the binding of [3H]phorbol-12,13-dibutyrate to PK-C alpha showed that only the threo-isomer, 5-O-tetradecanoyl-2,3-dideoxy-L-threo-hexono-1,4-lactone (2) was a good PK-C ligand (Ki = 1 microM). The rest of the ligands had poorer affinities with Ki values between 10 and 28 microM. With these results, the order of importance of five-membered ring lactones as competent templates for the construction of semirigid DAG surrogates with effective PK-C binding affinity can be established as II >> I approximately III > IV.

The stimulation of capsaicin-sensitive neurones in a vanilloid receptor-mediated fashion by pungent terpenoids possessing an unsaturated 1,4-dialdehyde moiety

1. The irritant fungal terpenoid isovelleral caused protective eye-wiping movements in the rat upon intraocular instillation and showed cross-tachyphylaxis with capsaicin, the pungent principle in hot pepper. 2. Isovelleral induced a dose-dependent calcium uptake by rat dorsal root ganglion neurones cultured in vitro with an EC50 of 95 nM, which was fully inhibited by the competitive vanilloid receptor antagonist capsazepine. 3. Isovelleral inhibited specific binding of [3H]-resiniferatoxin (RTX), an ultrapotent capsaicin analogue, to rat trigeminal ganglion or spinal cord preparations with an IC50 of 5.2 microM; in experiments in which the concentration of [3H]-RTX was varied, isovelleral changed both the apparent affinity (from 16 pM to 37 pM) and the co-operativity index (from 2.1 to 1.5), but not the Bmax. 4. The affinity of isovelleral for inducing calcium uptake or inhibiting RTX binding was in very good agreement with the threshold dose (2.2. nmol) at which it provoked pungency on the human tongue. 5. For a series of 14 terpenoids with an unsaturated 1,4-dialdehyde, a good correlation was found between pungency on the human tongue and affinity for vanilloid receptors on the rat spinal cord. 6. The results suggest that isovelleral-like compounds produce their irritant effect by interacting with vanilloid receptors on capsaicin-sensitive sensory neurones. Since these pungent diterpenes are structurally distinct from the known classes of vanilloids, these data provide new insights into structure-activity relations and may afford new opportunities for the development of drugs targeting capsaicin-sensitive pathways.

Non-equivalent roles for the first and second zinc fingers of protein kinase Cdelta. Effect of their mutation on phorbol ester-induced translocation in NIH 3T3 cells

Classical and novel protein kinase C (PKC) isozymes contain two, so-called cysteine-rich zinc finger domains that represent the binding sites for phorbol esters and the diacylglycerols. X-ray crystallographic, mutational, and modeling studies are providing detailed understanding of the interactions between the phorbol esters and individual PKC zinc fingers. In the present study, we explore the roles of the individual zinc fingers in the context of the intact enzyme. Our approach was to mutate either the first, the second, or both zinc fingers of PKCdelta, to express the mutated enzyme in NIH 3T3 cells, and to monitor the effect of the mutations on the dose-response curve for translocation induced by phorbol 12-myristate 13-acetate. The introduced mutations change into glycine the consensus proline in the phorbol ester binding loop of the zinc finger; in the isolated zinc finger, this mutation causes a 125-fold decrease in phorbol ester binding affinity. We observed that mutation in the first zinc finger caused almost no shift in the dose-response curve for translocation; mutation in the second zinc finger caused a 21-fold shift, whereas mutation in both zinc fingers caused a 138-fold shift. We conclude that the zinc fingers in the intact PKC are not equivalent and that the second zinc finger plays the predominant role in translocation of protein kinase Cdelta in response to phorbol 12-myristate 13-acetate. Our findings have important implications for the understanding and design of PKC inhibitors targeted to the zinc finger domains.

Differential activation of PKC isozymes by 14-3-3 zeta protein

14-3-3 proteins are ubiquitous in eukaryotes associated with many fundamental functions in signal transduction pathways and cell cycle regulation. Protein kinase C comprises a large family of serine/threonine protein kinases that are involved in cell growth and differentiation. Different protein kinase C isozymes have distinct roles in signal transduction pathways; protein kinase C epsilon is of particular interest because its overexpression leads to oncogenic transformation. The 14-3-3 protein has been reported to regulate the activity of protein kinase C, although the nature of its effect is equivocal. In this study we report the differential activation of various protein kinase C isoforms by 14-3-3 zeta protein. The classical isozymes show approximately a twofold activation, protein kinase C delta shows no significant increase in activity, whereas protein kinase C epsilon, another novel isozyme, is highly activated. This activation shows strong positive cooperativity with a Hill coefficient of 6.1 +/- 0.2.

Protein kinase C in cell signaling: strategies for the development of selective inhibitors

Protein kinase C plays a central role in the cellular signaling pathway for the lipophilic second messenger sn-1,2-diacylglycerol, which is involved in many biological responses, including tumor promotion and inflammation. A major effort has been directed at understanding diversity within this system in order to develop strategies for selective inhibition. Two classes of ligands for the regulatory domain of protein kinase C have been identified which, although they function in vitro as activators of the enzyme, paradoxically behave in vivo as partial antagonists. Identification of targets for the phorbol esters distinct from protein kinase C argues that antagonists acting on the regulatory and catalytic domains of protein kinase C will have different spectra of action.

[Revised evaluation of cardiomegaly in hypoglycemia in newborn infants]

Numerous data of the literature suggest that the cardiomegaly of hypoglycaemic newborns is due to low blood glucose levels. The size of the heart is usually determined by measuring the cardio-thoracic ratio (CTR). On the basis of the present retrospective study analyzing the clinical course and radiological findings of 66 newborns the authors suggest that: 1. CTR cannot reliably be used for determining the size of the heart in hypoglycaemic small for gestational age (SGA) newborns. 2. Routine look at the X-ray picture is also insufficient for the determination of the size of the heart in hypoglycaemic SGA newborns. 3. The method suggested by the authors is to measure the transverse diameter of the heart and to compare it to the normal, birthweight-related standard. In 3/4 of the hypoglycaemic SGA newborns studied thoracic transverse diameter (TTD) values were found to be smaller than the 50th percentile of the standard. Transverse diameter values of the heart, however, did not differ significantly from the normal mean values. In cases of true cardiomegaly, i.e. cardiac diameter above the 90th percentile, data indicative of asphyxia were more frequently seen.