Perinatal expression of heat-shock protein 27 in brain regions and nonneural tissues of the piglet

Important stressful events occur at birth or within the few hours that follow this event. To unravel a possible involvement of stress proteins, it is important to determine their levels of expression. Expression of HSP27 protein was determined by Western blotting in several nonneural tissues and in brain regions of the developing pig (fetal to adult). Maximum levels of expression were observed in heart, liver, and lung. In kidney, the expression was reduced during the first hours of life. Brain parts included whole brain, cerebellum, cortex, hippocampus, hypothalamus, and striatum. HSP27 immunogenicity was observed in all the brain regions studied. In whole brain, cerebellum, cortex, hippocampus, and hypothalamus extracts, the levels of HSP27 were decreased during the first hours of age (4 h to 2 d). In striatum, levels of expression were very low--if detectable--during the early postnatal days of life. Changes in environmental parameters, like temperature and/or hypoxia can be possibly related to differential expressions of HSPs, which can result in severe adverse developmental outcomes. The results are discussed in terms of using the newborn piglet as a model to study different forms of stress on the heat-shock protein postnatal expression.

Inhibition of Daxx-mediated apoptosis by heat shock protein 27

Heat shock protein 27 (HSP27) confers cellular protection against a variety of cytotoxic stresses and also against physiological stresses associated with growth arrest or receptor-mediated apoptosis. Phosphorylation modulates the activity of HSP27 by causing a major change in the supramolecular organization of the protein, which shifts from oligomers to dimers. Here we show that phosphorylated dimers of HSP27 interact with Daxx, a mediator of Fas-induced apoptosis, preventing the interaction of Daxx with both Ask1 and Fas and blocking Daxx-mediated apoptosis. No such inhibition was observed with an HSP27 phosphorylation mutant that is only expressed as oligomers or when apoptosis was induced by transfection of a Daxx mutant lacking its HSP27 binding domain. HSP27 expression had no effect on Fas-induced FADD- and caspase-dependent apoptosis. However, HSP27 blocked Fas-induced translocation of Daxx from the nucleus to the cytoplasm and Fas-induced Daxx- and Ask1-dependent apoptosis. The observations revealed a new level of regulation of the Fas pathway and suggest a mechanism for the phosphorylation-dependent protective function of HSP27 during stress and differentiation.

p38 MAP kinase pathway regulates angiotensin II-induced contraction of rat vascular smooth muscle

Angiotensin II (ANG II) is a multifunctional hormone that exerts potent vasoconstrictor and hypertrophic effects on vascular smooth muscle. Here, we demonstrate that the p38 mitogen-activated protein (MAP) kinase pathway is involved in ANG II-induced vascular contraction. Addition of ANG II to rat aortic smooth muscle cells (SMC) caused a rapid and transient increase of p38 activity through activation of the AT(1) receptor subtype. This response to ANG II was strongly attenuated by pretreating cells with antioxidants and diphenylene iodonium and was mimicked by exposure of cells to H(2)O(2). Stimulation of p38 by ANG II resulted in the enzymatic activation of MAP kinase-activated protein (MAPKAP) kinase-2 and the phosphorylation of heat shock protein 27 (HSP27) in aortic SMC. Pretreatment of cells with the specific p38 MAP kinase inhibitor SB-203580 completely blocked the ANG II-dependent activation of MAPKAP kinase-2 and phosphorylation of HSP27. ANG II also caused a robust activation of MAPKAP kinase-2 in the intact rat aorta. Incubation with SB-203580 significantly decreased the potency of ANG II to induce contraction of rat aortic rings and depressed the maximal hormone response. These results suggest that the p38 MAP kinase pathway selectively modulates the vasoconstrictor action of ANG II in vascular smooth muscle.

p38-dependent enhancement of cytokine-induced nitric-oxide synthase gene expression by heat shock protein 70

Heat shock protein (hsp) 70 protects cells against stress by means of its ability to chaperone denatured proteins and to modulate stress-activated signaling pathways. Because inflammatory processes are often accompanied by hsp expression and because stress and cytokines share several signaling pathways, we investigated the possibility that hsp70 might modulate the cellular response to cytokines. We found that stable cell clones overexpressing hsp70, or cells shortly after transfection with hsp70, produced 2 times more nitric oxide and inducible nitric-oxide synthase (iNOS) protein and mRNA in response to cytokines than control cells expressing undetectable amounts of hsp70. Since mitogen-activated protein kinases participate in the activation of iNOS by cytokines, we investigated whether hsp70 affected the activation of these signaling pathways. hsp70 overexpression led to a specific enhancement of the activation of the p38 pathway by cytokines, producing little or no effect on the activation of extracellular signal-regulated kinase or Jun N-terminal kinase. Blocking p38 activity with SB203580 totally abolished the enhancing effect of hsp70 on cytokine-induced endogenous iNOS mRNA accumulation or transcription of an iNOS promoter-driven luciferase gene, while having little effect on the cytokine response observed in control cells. We conclude that the p38 pathway acts as an enhancing factor in the activation of iNOS by cytokines and that hsp70 can modulate the cellular response to cytokines by acting on signaling elements upstream of p38.

The silencing protein SIR2 and its homologs are NAD-dependent protein deacetylases

Homologs of the chromatin-bound yeast silent information regulator 2 (SIR2) protein are found in organisms from all biological kingdoms. SIR2 itself was originally discovered to influence mating-type control in haploid cells by locus-specific transcriptional silencing. Since then, SIR2 and its homologs have been suggested to play additional roles in suppression of recombination, chromosomal stability, metabolic regulation, meiosis, and aging. Considering the far-ranging nature of these functions, a major experimental goal has been to understand the molecular mechanism(s) by which this family of proteins acts. We report here that members of the SIR2 family catalyze an NAD-nicotinamide exchange reaction that requires the presence of acetylated lysines such as those found in the N termini of histones. Significantly, these enzymes also catalyze histone deacetylation in a reaction that absolutely requires NAD, thereby distinguishing them from previously characterized deacetylases. The enzymes are active on histone substrates that have been acetylated by both chromatin assembly-linked and transcription-related acetyltransferases. Contrary to a recent report, we find no evidence that these proteins ADP-ribosylate histones. Discovery of an intrinsic deacetylation activity for the conserved SIR2 family provides a mechanism for modifying histones and other proteins to regulate transcription and diverse biological processes.

Vascular endothelial growth factor (VEGF)-driven actin-based motility is mediated by VEGFR2 and requires concerted activation of stress-activated protein kinase 2 (SAPK2/p38) and geldanamycin-sensitive phosphorylation of focal adhesion kinase

In endothelial cells, vascular endothelial growth factor (VEGF) induces an accumulation of stress fibers associated with new actin polymerization and rapid formation of focal adhesions at the ventral surface of the cells. This cytoskeletal reorganization results in an intense motogenic activity. Using porcine endothelial cells expressing one or the other type of the VEGF receptors, VEGFR1 or VEGFR2, or human umbilical vein endothelial cells pretreated with a VEGFR2 neutralizing antibody, we show that VEGFR2 is responsible for VEGF-induced activation of the stress-activated protein kinase-2/p38 (SAPK2/p38), phosphorylation of focal adhesion kinase (FAK), and enhanced migratory activity. Activation of SAPK2/p38 triggered actin polymerization whereas FAK, which was phosphorylated independently of SAPK2/p38, initiated assembly of focal adhesions. Both processes contributed to the formation of stress fibers. Geldanamycin, an inhibitor of HSP90 blocked tyrosine phosphorylation of FAK, assembly of focal adhesions, actin reorganization, and cell migration, all of which were reversed by overexpressing HSP90. We conclude that VEGFR2 mediates the physiological effect of VEGF on cell migration and that two independent pathways downstream of VEGFR2 regulate actin-based motility. One pathway involves SAPK2/p38 and leads to enhanced actin polymerization activity. The other involves HSP90 as a permissive signal transduction factor implicated in FAK phosphorylation and assembly of focal adhesions.

Overexpression of the 27 KDa heat shock protein is associated with thermoresistance and chemoresistance but not with radioresistance

PURPOSE

The heat shock protein (hsp27) correlates with thermotolerance and chemoresistance. Our main objective was to assess the response to radiotherapy both in vitro and in vivo in correlation with various concentrations of hsp27. The second objective was to evaluate the relation between hsp27 and glutathione-s-transferase pi (GST pi).

METHODS AND MATERIALS

For the in vitro study, thermoresistant cell lines, expressing various amounts of hsp27, were used to assess the role of this protein in radioresistance. To verify the efficiency of hsp27 in these cells lines to confer resistance to cytotoxic agents, these cells were also treated with heat shock and cisplatin. Furthermore, the role of hsp27 expression was studied in vivo by immunochemistry in 98 patients with head and neck squamous cell carcinoma treated by radiotherapy. hsp27 was correlated with local control of the tumor and with clinical and biologic factors potentially able to affect the local control, including p53, ki-67, ploidy, and GST.

RESULTS

In vitro, high constitutive levels of expression of hsp27 did not significantly influence the survival curves of transfected cells exposed to radiation as compared to control cells although hsp27 overexpression was confirmed to increased the cellular resistance to heat and to cisplatinum. In vivo, we showed that overexpression of various amounts of hsp27 did not correlate with local control of the tumor. In vivo, hsp27 was only significantly associated with GST pi. Expression of GST pi was associated with poor local (p = 0.01) control and survival (p = 0.08) in a Cox model.

CONCLUSIONS

It is concluded that the mechanisms responsible for hsp27-mediated heat and drug resistance are not involved in radioprotection.

Outcome of patients receiving radiation for cancer of the esophagus: results of the 1992-1994 Patterns of Care Study

PURPOSE

A Patterns of Care Study examined the records of patients with esophageal cancer (EC) treated with radiation in 1992 through 1994 to determine the national practice processes of care and outcomes and to compare the results with those of clinical trials.

PATIENTS AND METHODS

A national survey of 63 institutions was conducted using two-stage cluster sampling, and specific information was collected on 400 patients with squamous cell (62%) or adenocarcinoma (37%) of the thoracic esophagus who received radiation therapy (RT) as part of primary or adjuvant treatment. Patients were staged according to a modified 1983 American Joint Committee on Cancer staging system. Fifteen percent of patients had clinical stage (CS) I disease, 40% had CS II disease, and 30% had CS III disease. Twenty-six percent of patients underwent esophagectomy. Seventy-five percent of patients received chemotherapy; 84% of these received concurrent chemotherapy and radiation (CRT).

RESULTS

Significant variables for overall survival in multivariate analysis include the use of esophagectomy (risk ratio [RR] = 0.62), the use of chemotherapy (RR = 0.63), Karnofsky performance status (KPS) greater than 80 (RR = 0.61), CS I or II disease (RR = 0.66), and facility type (RR = 0.72). Age, sex, and histology were not significant. Preoperative CRT resulted in a nonsignificantly higher 2-year survival rate compared with definitive CRT alone (63% v 39%; P =.11), whereas 2-year survival by planned treatment rather than treatment given was 47.7% for preoperative CRT and 35.4% for definitive CRT (P =.23). Definitive CRT compared with definitive RT alone resulted in significantly higher 2-year survival (39% v 20.6%; P =.027) and lower 2-year local regional failure (30% v 57.9%; P =. 0031).

CONCLUSION

This study confirms the value of CRT in EC treatment. It indicates that the results obtained in practice settings nationwide are similar to those obtained in clinical trials and that KPS and the 1983 clinical staging system are useful prognostic indicators. The suggested value of esophagectomy and superiority of preoperative CRT over CRT alone in this study should be tested in a randomized trial.

A short lived protein involved in the heat shock sensing mechanism responsible for stress-activated protein kinase 2 (SAPK2/p38) activation

The stress-activated protein kinase 2 (SAPK2/p38) is activated by various environmental stresses and also by a vast array of agonists including growth factors and cytokines. This implies the existence of multiple proximal signaling pathways converging to the SAPK2/p38 activation cascade. Here, we show that there is a sensing mechanism highly specific to heat shock for activation of SAPK2/p38. After mild heat shock, cells became refractory to reinduction of the SAPK2/p38 pathway by a second heat shock. This was not the result of a toxic effect because the cells remained fully responsive to reinduction by other stresses, cytokines, or growth factors. Neither the activity of SAPK2/p38 itself nor the accumulation of the heat shock proteins was essential in the desensitization process. The cells were not desensitized to heat shock by other treatments that activated SAPK2/p38. Moreover, inhibiting SAPK2/p38 activity during heat shock did not block desensitization. Also, overexpression of HSP70, HSP27, or HSP90 by gene transfection did not cause desensitization, and inhibiting their synthesis after heat shock did not prevent desensitization. Desensitization rather appeared to be linked closely to the turnover of a putative upstream activator of SAPK2/p38. Cycloheximide induced a progressive and eventually complete desensitization. The effect was specific to heat shock and minimally affected activation by other stress inducers. Inhibiting protein degradation with MG132 caused the constitutive activation of SAPK2/p38, which was blocked by a pretreatment with either cycloheximide or heat shock. The results thus indicate that there is a sensing pathway highly specific to heat shock upstream of SAPK2/p38 activation. The pathway appears to involve a short lived protein that is the target of rapid successive up- and down-regulation by heat shock.

Long-term follow-up of patients with rectal cancer managed by local excision with and without adjuvant irradiation

OBJECTIVE

The long-term outcomes of patients undergoing local excision with or without pelvic irradiation were examined to define the role of adjuvant irradiation after local excision of T1 and T2 rectal cancers.

METHODS

Ninety-nine patients with T1 or T2 rectal cancers underwent local excision with or without adjuvant irradiation at Massachusetts General Hospital and Emory University Hospital between January 1966 and January 1997. Of these, 52 patients were treated by local excision alone and 47 patients by local excision plus adjuvant irradiation. Twenty-six of these 47 patients were treated by irradiation in combination with 5-fluorouracil chemotherapy. The outcomes of these groups were compared.

RESULTS

The 5-year actuarial local control and recurrence-free survival rates were 72% and 66%, respectively, for the local excision alone group and 90% and 74%, respectively, for the adjuvant irradiation group. This improvement in outcome was evident despite the presence of a higher-risk patient population in the adjuvant irradiation group. Adverse pathologic features such as poorly differentiated histology and lymphatic or blood vessel invasion decreased local control and recurrence-free survival rates in the local excision only group. Adjuvant irradiation significantly improved 5-year outcomes in patients with high-risk pathologic features. Four cases of late local recurrence were seen at 64, 72, 86, and 91 months in the adjuvant irradiation group.

CONCLUSIONS

The authors recommend adjuvant chemoradiation for all patients undergoing local excision for T2 tumors, and for T1 tumors with high-risk pathologic features. The four cases of late local failures beyond 5 years in the adjuvant irradiation group underscores the need for careful long-term follow-up in these patients.

The evaluation and treatment of patients receiving radiation therapy for carcinoma of the esophagus: results of the 1992-1994 Patterns of Care Study

BACKGROUND

For the first time, a Patterns of Care Study (PCS) was conducted in 1992-1994 to determine the national practice standards in evaluating and treating patients with esophageal carcinoma and to determine the degree to which clinical trials have been incorporated into national practice.

METHODS

A national survey of 61 institutions using 2-stage cluster sampling was conducted, and specific information was collected on 400 patients with squamous cell carcinoma or adenocarcinoma of the thoracic esophagus who received radiation therapy (RT) as part of definitive or adjuvant management of their disease. Patients were staged according to a modified 1983 American Joint Committee on Cancer staging system. Chi-square tests for significant differences between academic and nonacademic institutions for a particular variable were performed.

RESULTS

The median age of patients was 66.7 years (range, 26-89 years); 76.5% were male and 23.5% were female. Karnofsky performance status was > or = 80 for 88.3% of patients. Squamous cell carcinoma was diagnosed in 61.5% and adenocarcinoma in 36.8%. Fifteen percent were Clinical Stage (CS) I, 39.5% CS II, and 29.5% CS III. Evaluative procedures included endoscopy (>93%), computed tomography (CT) of the chest (86%), CT of the abdomen (75%), esophagography (68.5%), and endoscopic ultrasound (3.5%). Endoscopic ultrasound and CT of the chest were performed significantly more frequently at academic than nonacademic facilities (6.1% vs. 1.0% and 91.9% vs. 81.3%, respectively). Three-quarters of all patients received chemotherapy and RT and 62.5% received concurrent chemotherapy and RT as part of their treatment. Treatments included chemotherapy plus RT (54.0%), RT alone (20.3%), preoperative chemotherapy + RT (13.3%), postoperative chemotherapy + RT (7.7%), postoperative RT (3.5%), and preoperative RT (1.2%). The chemotherapeutic agents most frequently used were 5-fluorouracil (84%), cisplatin (64%), and mitomycin (9%); academic instututions used cisplatin significantly more often and mitomycin significantly less often than nonacademic institutions. Brachytherapy was used in 8.5% of cases. The median total dose of external beam radiation was 50.4 gray and the median dose per fraction was 1.8 gray.

CONCLUSIONS

This study establishes the national benchmarks for the evaluation and treatment of patients with esophageal carcinoma at radiation facilities in the U.S. It also indicates that the majority of patients given RT as a component of treatment for esophageal carcinoma receive chemoradiation rather than RT alone, as supported by clinical trials. Although some differences in the evaluation of esophageal carcinoma were noted between academic and nonacademic facilities, there was no difference in the frequency of use of chemoradiation versus RT by facility type.

Cloning and characterization of hGMEB1, a novel glucocorticoid modulatory element binding protein

A 21-bp element called glucocorticoid modulatory element (GME) modulates the glucocorticoid receptor-mediated responses via the binding of an as yet poorly characterized transacting complex of proteins containing the 88-kDa GMEB1 and the 67-kDa GMEB2. Using heat shock protein 27 (HSP27) as bait in the yeast two-hybrid assay, we cloned a 1.83-kb cDNA encoding a novel 573-amino acid protein called human GMEB1 (hGMEB1). hGMEB1 possesses a KDWK domain, contains sequences almost identical (36/38) to three tryptic peptides of rat GMEB1 and shares 38% identity with rat GMEB2. hGMEB1 is ubiquitously expressed as a 85-kDa protein in all cell lines and tissues examined. In vitro translated hGMEB1 bound specifically to GME oligonucleotides yielding a complex of similar size to the complex obtained using rat liver nuclear extracts. Both complexes were supershifted with an antibody specific to hGMEB1. Co-immunoprecipitation experiments confirmed the in vivo interaction of HSP27 with hGMEB1.

Embryonic death of Mek1-deficient mice reveals a role for this kinase in angiogenesis in the labyrinthine region of the placenta

Mek is a dual-specificity kinase that activates the extracellular-signal-regulated (Erk) mitogen-activated protein (MAP) kinases upon agonist binding to receptors. The Erk MAP kinase cascade is involved in cell-fate determination in many organisms. In mammals, this pathway is proposed to regulate cell growth and differentiation. Genetic studies have shown that although a single mek gene is present in Caenorhabditis elegans, Drosophila and Xenopus, two mek homologs, Mek1 and Mek2, are present in the mammalian cascade. In the present study, we describe a mutant mouse line in which the mek1 gene has been disrupted by insertional mutagenesis. The null mutation was recessive lethal, as the homozygous mutant embryos died at 10.5 days of gestation. Histopathological analyses revealed a reduction in vascularization of the placenta that was due to a marked decrease of vascular endothelial cells in the labyrinthine region. The failure to establish a functional placenta probably explains the death of the mek1-/- embryos. Cell-migration assays indicated that mek1-/- fibroblasts could not be induced to migrate by fibronectin, although the levels of Mek2 protein and Erk activation were normal. Re-expression of Mek1 in the mutant mouse embryonic fibroblasts (MEFs) restored their ability to migrate. Our findings provide genetic evidence that establishes the unique role played by Mek1 in signal transduction. They also suggest that mek1 function is required for normal response to angiogenic signals that might promote vascularization of the labyrinthine region of the placenta.

HSP27 multimerization mediated by phosphorylation-sensitive intermolecular interactions at the amino terminus

Distinct biochemical activities have been reported for small and large molecular complexes of heat shock protein 27 (HSP27), respectively. Using glycerol gradient ultracentrifugation and chemical cross-linking, we show here that Chinese hamster HSP27 is expressed in cells as homotypic multimers ranging from dimers up to 700-kDa oligomers. Treatments with arsenite, which induces phosphorylation on Ser15 and Ser90, provoked a major change in the size distribution of the complexes that shifted from oligomers to dimers. Ser90 phosphorylation was sufficient and necessary for causing this change in structure. Dimer formation was severely inhibited by replacing Ser90 with Ala90 but not by replacing Ser15 with Ala15. Using the yeast two-hybrid system, two domains were identified that were responsible for HSP27 intermolecular interactions. One domain was insensitive to phosphorylation and corresponded to the C-terminal alpha-crystallin domain. The other domain was sensitive to serine 90 phosphorylation and was located in the N-terminal region of the protein. Fusion of this N-terminal domain to firefly luciferase conferred luciferase with the capacity to form multimers that dissociated into monomers upon phosphorylation. A deletion within this domain of residues Arg5-Tyr23, which contains a WDPF motif found in most proteins of the small heat shock protein family, yielded a protein that forms only phosphorylation-insensitive dimers. We propose that HSP27 forms stable dimers through the alpha-crystallin domain. These dimers further multimerize through intermolecular interactions mediated by the phosphorylation-sensitive N-terminal domain.

Assessment and intervention with clients with apraxia: contributions from the literature

Individuals with praxis problems encounter difficulties engaging in occupation, and the occupational therapists who work with these clients are challenged to provide intervention that enables occupational performance. This extensive review of the current literature provides clinicians with information regarding the relevant descriptions and suggested mechanisms of apraxia. Errors noted in performance, different classification systems and the implications of the current knowledge will be discussed. The paper concludes by providing information for clinicians regarding occupational therapy evaluation and intervention strategies for praxis problems.

Regulation of actin dynamics by stress-activated protein kinase 2 (SAPK2)-dependent phosphorylation of heat-shock protein of 27 kDa (Hsp27)

Activation of the mitogen-activated protein kinase (MAP kinase) SAPK2 (stress-activated protein kinase 2) leads to the phosphorylation of several transcription factors and cytoplasmic proteins, and thereby presumably orchestrates important specific cellular responses to numerous cytokines, stressing agents and agonists of tyrosine kinase or serpentine receptors. The heat-shock protein of 27 kDa (Hsp27), a downstream target of the SAPK2-activated MAP-kinase-activated protein kinase-2/3, has a documented function as an actin polymerization modulator. Accordingly, recent evidence implicates the SAPK2 pathway in the modulation of microfilament dynamics in response to stress and agonist stimulation. In vascular endothelial cells, where the basal level of expression of Hsp27 is high, SAPK2 mediates oxidative stress- and vascular endothelial growth factor (VEGF)-induced actin reorganization and VEGF-induced cell migration, suggesting a key role for this MAP kinase pathway in inflammation and angiogenic processes.

Critical survey of interrelationships of nitrogen and amino acids in seeds

The present paper is intended for removing inconsistencies from available information concerning the interrelationhips of nitrogen (N) and amino acids in seeds (or grains). It consists of a critical survey of data reported in a series of papers by Mossé and collaborators (see Mossé and Huet, Sci. Aliments 1990, 10, 151 for review). These authors contended for perfectly linear relationships (A(i) = a(i)N + b(i)) to hold between N and amino acid i (g/100 g seed dry matter) for seeds of a given species on the basis of correlation coefficient (r) found to be close to 1. Three linear regressions are called upon to analyze variations in the amino acid compositions of 33 samples of pea seeds. The regression C(i) (g amino acid i/16gN) = 16a(i) + 16b(i)N(-)(1), not used customarily, is the more amenable to accommodate all the facts in pointing out values significantly lower than 1 for r(i)(2), and parameters a(i) and b(i) similar to those found with the regression A(i) = NC(i)/16 = a(i)N + b(i) whose r(i)(2) values, very close to 1, are overestimated on account of the presence of N in both sides of equation and sampling limited in number. Examination of variations in lysine content of maize grains as a function of N shows that the phenotypic variations for a given genotype are a poor fit to the linear relationship A(lys) = aN + b available in the literature, as determined from 153 commercial samples. It is concluded that linear N-amino acid relationships hold only approximately for predicting amino acid composition of seed of a given species from its N content.

Practical considerations of outpatient infusion therapy in the HIV arena

In conclusion, OPAT is a cost-effective, quality-controlled alternative setting for treating patients with HIV. The program provides a desirable situation for the patient, physician, and nurse. Continuity of care provided by the health care team in the physician's office is a unique situation that can meet the treatment modalities necessary to care for the HIV patient with dignity and pride. In short, OPAT offers an attractive alternative to long-term hospitalization for a variety of HIV-related infections. Such therapy is rapidly becoming a standard of treatment that provides both cost savings and efficacious medical care to patients with HIV-related complications.

SAPK2/p38-dependent F-actin reorganization regulates early membrane blebbing during stress-induced apoptosis

In endothelial cells, H2O2 induces the rapid formation of focal adhesion complexes at the ventral face of the cells and a major reorganization of the actin cytoskeleton into dense transcytoplasmic stress fibers. This change in actin dynamics results from the activation of the mitogen-activated protein (MAP) kinase stress-activated protein kinase-2/p38 (SAPK2/p38), which, via MAP kinase-activated protein (MAPKAP) kinase-2/3, leads to the phosphorylation of the actin polymerization modulator heat shock protein of 27 kD (HSP27). Here we show that the concomitant activation of the extracellular signal-regulated kinase (ERK) MAP kinase pathway by H2O2 accomplishes an essential survival function during this process. When the activation of ERK was blocked with PD098059, the focal adhesion complexes formed under the plasma membrane, and the actin polymerization activity led to a rapid and intense membrane blebbing. The blebs were delimited by a thin F-actin ring and contained enhanced levels of HSP27. Later, the cells displayed hallmarks of apoptosis, such as DEVD protease activities and internucleosomal DNA fragmentation. Bleb formation but not apoptosis was blocked by extremely low concentrations of the actin polymerization inhibitor cytochalasin D or by the SAPK2 inhibitor SB203580, indicating that the two processes are not in the same linear cascade. The role of HSP27 in mediating membrane blebbing was assessed in fibroblastic cells. In control fibroblasts expressing a low level of endogenous HSP27 or in fibroblasts expressing a high level of a nonphosphorylatable HSP27, H2O2 did not induce F-actin accumulation, nor did it generate membrane blebbing activity in the presence or absence of PD098059. In contrast, in fibroblasts that expressed wild-type HSP27 to a level similar to that found in endothelial cells, H2O2 induced accumulation of F-actin and caused bleb formation when the ERK pathway was inhibited. Cis-platinum, which activated SAPK2 but induced little ERK activity, also induced membrane blebbing that was dependent on the expression of HSP27. In these cells, membrane blebbing was not followed by caspase activation or DNA fragmentation. We conclude that the HSP27-dependent actin polymerization-generating activity of SAPK2 associated with a misassembly of the focal adhesions is responsible for induction of membrane blebbing by stressing agents.

Expression of heat shock proteins in mouse skin during wound healing

Wound healing conditions generate a stressful environment for the cells involved in the regeneration process and are therefore postulated to influence the expression of heat shock proteins (Hsps). We have examined the expression of four Hsps (Hsp27, Hsp60, Hsp70 and Hsp90) and a keratin (keratin 6) by immunohistochemistry during cutaneous wound repair from Day 1 to Day 21 after wounding in the mouse. Hsps were constitutively expressed in normal mouse epidermis and their patterns of expression were modified during the healing process. The changes were not directly linked to the time course of the healing process but rather were dependent on the location of cells in the regenerating epidermis. In the thickened epidermis, Hsp60 was induced in basal and low suprabasal cells, Hsp70 showed a reduced expression, and Hsp90 and Hsp27 preserved a suprabasal pattern with an induction in basal and low suprabasal cells. All Hsps had a uniform pattern of expression in the migrating epithelial tongue. These observations suggest that the expression of Hsps in the neoepidermis is related to the proliferation, the migration, and the differentiation states of keratinocytes within the wound.

Patterns of care study decision tree and management guidelines for esophageal cancer. American College of Radiology

PURPOSE

The Patterns of Care Study (PCS) of the American College of Radiology periodically develops a decision tree and current management guidelines for major malignancies where radiation has an important role. The decision tree is a framework which depicts the division of patients into treatment groups. The treatment guidelines are useful in management and also serve as a starting point for quality assessment. For the first time, PCS decided to develop consensus management guidelines for esophageal cancer.

MATERIALS AND METHODS

A consensus panel was convened to define the key issues and develop guidelines for esophageal cancer management. A modified Delphi process was used to achieve consensus.

RESULTS

The consensus panel developed guidelines for the management of patients with adenocarcinoma or squamous cell carcinoma of the esophagus with a Karnofsky performance status of over 50. Patients with clinical stage I or II esophageal cancer can be treated with curative intent using either a primary surgical or primary chemoradiation approach. For patients with clinical stage III malignancy, where the most common approaches are palliative, surgical resection is generally not recommended and chemoradiation is the preferred treatment.

CONCLUSION

The PCS has developed treatment guidelines for esophageal cancer based on consensus committee deliberations. These guidelines can be useful for those who manage esophageal cancer.

Radiation therapy for rectosigmoid and rectal cancer: results of the 1992-1994 Patterns of Care process survey

PURPOSE

To determine the US national practice standards for patients with adenocarcinoma of the rectum treated in radiation oncology facilities.

MATERIALS AND METHODS

A national survey of 57 institutions identified 507 eligible patients who received radiation therapy as a component of their treatment for rectal cancer. A stratified two-stage cluster sampling with simple random sampling at each stage for each stratum was used and on-site surveys were performed.

RESULTS

Of the 507 patients, 378 (75%) received postoperative therapy, 110 (22%) received preoperative therapy, 17 (2%) received both preoperative and postoperative therapy, and less than 0.5% received intraoperative radiation alone. To more accurately assess the utilization of modern radiation techniques as well as recommendations of the National Cancer Institute (NCI)-sponsored, randomized, postoperative, adjuvant combined modality therapy rectal cancer trials into current practice, the analysis was limited to the 243 (48%) patients with tumor, node, and metastasis staging system classification T3 and/or N1-2M0 disease who underwent conventional surgery with negative margins. Although only 7% were treated on a clinical trial, 90% received chemotherapy for a median of 21 weeks. Most were treated with modern radiation treatment techniques. In contrast, techniques to identify and help exclude the small bowel from the radiation field were not routinely used.

CONCLUSION

Despite the fact that only 7% of patients with T3 and/or N1-2M0 disease were treated on a clinical trial, such trials appear to have resulted in a positive influence on the standard of practice within the oncology community. Although there are still some deficiencies, the majority of these patients received combined modality therapy and were treated with modern radiation therapy techniques.

Treatment systems guidelines for primary rectal cancer from the 1996 Patterns of Care Study

PURPOSE

The Patterns of Care Rectal Cancer Committee was formed to develop consensus recommendations for patients with adenocarcinoma of the rectum limited to the pelvis.

METHODS AND MATERIALS

The Committee was composed of a multidisciplinary group of oncologists, and clinical scenarios were chosen to address most of the major treatment controversies in the combined modality treatment of rectal cancer. A literature search was then conducted and the major articles were identified. A modified Delphi technique was used to arrive at consensus. Serial surveys were conducted by distributing questionnaires to the Committee members to consolidate expert opinion. Voting was conducted using a scoring system and opinions were unified to the highest degree possible.

RESULTS

Consensus voting was performed for 4 clinical scenarios. Acceptability ratings for treatment were grouped into 3 broad categories: not acceptable, acceptable, and most acceptable. Based on the treatment options, a decision tree was developed that reflects the consensus of the committee.

CONCLUSION

These options may help guide treatment decisions in rectal cancer.

Role of the mitogen-activated protein kinases in the expression of the kinin B1 receptors induced by tissue injury

Several cytokines and LPS regulate the population of the B1 receptors (B1Rs) for kinins; these are responsive to des-Arg9-bradykinin (BK) and Lys-des-Arg9-BK. B1R activation contributes to inflammatory vascular changes and pain. Aortic rings isolated from normal rabbits and incubated in vitro in Krebs physiological medium were used as a model of tissue injury. From a null level of response, these rings exhibit a time- and protein synthesis-dependent increase in the maximal contractile response to des-Arg9-BK. Exposure to exogenous IL-1beta or epidermal growth factor (EGF) considerably increases the process of sensitization to the kinins. Freshly isolated control aortic rings showed high mitogen-activated protein (MAP) kinase activities (persistent activation of p38, but less prolonged for extracellular signal-regulated kinase and c-Jun-N-terminal kinase/stress-activated protein kinase pathways) relatively to the basal activities found in various types of cultured cells. IL-1beta or EGF further increased the activities of the extracellular signal-regulated kinase and c-Jun-N-terminal kinase/stress-activated protein kinase MAP kinases. The inhibitor of the p38 MAP kinase, SB 203580 (10 microM), massively (approximately 75%) and selectively inhibited the spontaneous sensitization to des-Arg9-BK over 6 h. SB 203580 also significantly reduced the development of the response to des-Arg9-BK as stimulated by IL-1 or EGF. Both spontaneous and IL-1beta-stimulated up-regulation of responsiveness to des-Arg9-BK were significantly inhibited by the MAP kinase extracellular signal-regulated kinase kinase 1 inhibitor PD 98059 (approximately 40%). The protein kinase inhibitors failed to inhibit protein synthesis and to acutely inhibit the contractile effect of des-Arg9-BK, suggesting that they do not influence B1 receptor transduction mechanisms. In cultured aortic smooth muscle cells stimulated with EGF, MAP kinase activation preceded B1R mRNA induction. Protein kinase inhibitors reveal the role of cell injury-controlled MAP kinase pathways, and singularly of the p38 pathway, in the induction of B1R.

p38 MAP kinase activation by vascular endothelial growth factor mediates actin reorganization and cell migration in human endothelial cells

Vascular endothelial growth factor (VEGF) is a potent chemotactic agent for endothelial cells. Yet the signalling pathways that modulate the motogenic effects of VEGF in vascular endothelial cells are still ill defined. In the present study, we found in primary cultures of human umbilical vein endothelial cells (HUVEC) that VEGF increased cell migration and induced a marked reorganization of the microfilament network that was characterized by the formation of stress fibers and the recruitment of vinculin to focal adhesions. VEGF also stimulated the mitogen activated protein (MAP) kinases ERK (extracellular signal-regulated kinase) and p38 (stress activated protein kinase-2), but not SAPK1/JNK (stress activated protein kinase-1/c-Jun NH2-terminal kinase). Activation of p38 resulted in activation of MAP kinase activated protein kinase-2/3 and phosphorylation of the F-actin polymerization modulator, heat shock protein 27 (HSP27). Inhibiting the VEGF-induced activation of ERK with PD098059 did not influence actin organization or cell migration but totally inhibited the VEGF-induced incorporation of thymidine into DNA. Inhibition of p38 activity by the specific inhibitor SB203580 led to an inhibition of HSP27 phosphorylation, actin reorganization and cell migration. The results indicate that the p38 pathway conveys the VEGF signal to microfilaments inducing rearrangements of the actin cytoskeleton that regulate cell migration. By modulating cell migration, p38 may thus be an important regulator of angiogenesis.

Mammalian cells adapted to growth at pH 6.7 have elevated HSP27 levels and are resistant to cisplatin

HSP27 levels are elevated in two Chinese hamster cell lines and in a human melanoma cell line adapted to growth at pH 6.7. The level of HSP72 is elevated in the melanoma cell line but not in the hamster cell lines adapted to growth at pH 6.7. HSC73 levels are not elevated in any of the adapted cell lines. Low pH adapted cells from all cell lines are resistant to cisplatin. It is proposed that elevated HSP27 levels in low pH-adapted cells may play a role in resistance to hyperthermia and resistance to cisplatin.

Cholecystokinin stimulates heat shock protein 27 phosphorylation in rat pancreas both in vivo and in vitro

BACKGROUND & AIMS

Mammalian heat shock protein 27 (hsp27) is believed to function under normal physiological conditions and during cellular stress. Recent studies indicate a role for hsp27 in regulating actin-cytoskeletal dynamics. In the present study, secretagogue-regulated phosphorylation of hsp27 in rat exocrine pancreas was investigated both in vivo and in isolated acinar cells.

METHODS

Western analysis after two-dimensional electrophoresis was used to measure the phosphorylation of hsp27 after treatment of rats or acinar cells with secretagogues. Cholecystokinin-stimulated mitogen-activated protein kinase-activated protein (MAPKAP) kinase 2 activity was measured after immunoprecipitation of the kinase.

RESULTS

hsp27 exists as three isoforms in acini: one nonphosphorylated (pI 6.2) and two phosphorylated (pIs 5.9 and 5.7) forms. Infusion of rats with a secretory or supermaximal dose of cerulein produced an acidic shift in hsp27, indicating an increase in its phosphorylation; the higher dose, known to cause pancreatitis, had a twofold greater effect. In isolated acini, increases in hsp27 phosphorylation were evident at 10 pmol/L and maximal at 1 nmol/L cholecystokinin. The hsp27-specific kinase MAPKAP kinase 2 was activated 2.4-fold with 1 nmol/L cholecystokinin treatment.

CONCLUSIONS

hsp27 phosphorylation was stimulated by low and high concentrations of cholecystokinin, both in vivo and in vitro. Phosphorylation was potentially mediated via the MAPKAP kinase 2 intracellular signaling pathway.

Oxidative stress-induced actin reorganization mediated by the p38 mitogen-activated protein kinase/heat shock protein 27 pathway in vascular endothelial cells

Vascular endothelial cells are constantly in contact with oxyradicals and must be especially well equipped to resist their toxic effects and generate appropriate physiological responses. Despite the importance of oxyradicals in the physiopathology of the vascular endothelium, the mechanisms regulating the oxidative response of endothelial cells are poorly understood. In the present study, we observed that H2O2 in concentrations that induced severe fragmentation of F-actin in fibroblasts rather induced a reorganization of F-actin in primary cultures of human umbilical vein endothelial cells (HUVECs) that was characterized by the accumulation of stress fibers, the recruitment of vinculin to focal adhesions, and the loss of membrane ruffles, H2O2 also induced in these cells a strong (10- to 14-fold) activation of the p38 mitogen-activated protein (MAP) kinase, which resulted in activation of MAP kinase-activated protein kinase-2/3 and phosphorylation of the F-actin polymerization modulator, heat shock protein 27 (HSP27). The MAP kinases extracellular-regulated kinase, and c-Jun N-terminal kinase/stress-activated protein kinase were only slightly increased by these treatments. Inhibiting p38 activity with the highly specific inhibitor SB203580 blocked the H2O2-induced endothelial microfilament responses. Moreover, fibroblasts acquired an endothelium-like SB203580-sensitive actin response when HSP27 concentration was increased by gene transfection to the same high level as found in HUVECs. The results indicate that activation of p38 MAP kinase in cells such as endothelial cells, which naturally express high level of HSP27, plays a central role in modulating microfilament responses to oxidative stress. Consequently, the p38 MAP kinase pathway may participate in the several oxyradical-activated functions of the endothelium that are associated with reorganization of microfilament network.

Regulation of actin filament dynamics by p38 map kinase-mediated phosphorylation of heat shock protein 27

We have studied the contribution of the individual kinases of the MAP (mitogen-activated protein) kinase family, including ERK (extracellular-signal regulated kinase), JNK/SAPK (c-JUN NH2-terminal kinase/stress-activated protein kinase) and p38, to activation of the HSP27 (heat shock protein 27) kinase MAPKAP kinase-2/3 and to HSP27 phosphorylation in Chinese hamster CCL39 cells stimulated by either growth factors, cytokines or stressing agents. In vitro assays using fractionated cell extracts or immunoprecipitates indicated that only fractions containing ERK or p38, and not those containing JNK/SAPK, had the capacity to activate MAPKAP kinase-2/3. In vivo, however, it appeared that only p38 is an upstream activator of HSP27 phosphorylation after both stress or growth factor stimulation: expression of an interfering mutant of ras, which blocked the activation of ERK by both types of inducers, had no effect on HSP27 phosphorylation and p38 activation; and the cell-permeant specific inhibitor of 038, SB203580, blocked MAPKAP-kinase2/3 activation and HSP27 phosphorylation. HSP27 has been suggested to have a phosphorylation-activated homeostatic function at the actin cytoskeleton level. This raises the possibility that p38 might be directly involved in mediating actin responses to external stimuli. Accordingly, we observed that a prior activation of p38 increased the stability of the actin microfilaments in cells exposed to cytochalasin D. The effect was dependent on the expression of HSP27 and was totally annihilated by blocking the p38 activity with SB203580. The results provide strong support to the idea that activation of p38 during adverse environmental conditions serves a homeostatic function aimed at regulating actin dynamics that would otherwise be destabilized during stress. Its activation during normal agonist stimulation may constitute an additional actin signaling pathway, the importance of which depends on the level of expression of HSP27.

Expression of the 27,000 mol. wt heat shock protein following kainic acid-induced status epilepticus in the rat

Western analysis and immunohistochemistry were used to determine the time-course and the distribution of the 27,000 mol. wt heat shock protein, Hsp27, in rat brain following systemic administration of kainic acid. No Hsp27 immunoreactivity was detected in naive control animals or in rats that failed to develop status epilepticus. Hsp27 immunoreactivity was detected as early as 12 h in the parietal cortex, piriform cortex and the hippocampus of rats that developed status epilepticus. The number of cells expressing Hsp27 and the intensity of Hsp27 immunoreactivity were increased 24 h after kainic acid administration. Hsp27 immunoreactivity was still observed seven days post-kainic acid injection. The morphology of the Hsp27-positive cells and double immunofluorescence against Hsp27 and glial fibrillary acidic protein revealed that Hsp27-positive cells were astrocytes. In addition, the distribution of Hsp27 suggested that astrocytic Hsp27 was dependent on excitation-induced metabolic stress rather than the direct effect of kainic acid on astrocytes.

Immediate breast reconstruction for stage III breast cancer using transverse rectus abdominis musculocutaneous (TRAM) flap

BACKGROUND

The management of state III breast cancer is challenging; it often includes multimodal treatment with systemic therapy and/or radiation therapy and surgery. Immediate breast reconstruction has not traditionally been performed in these patients. We review the results of immediate transverse rectus abdominis musculocutaneous (TRAM) flap in 21 patients treated for stage III breast cancer.

METHODS

Data have been collected retrospectively on 21 patients diagnosed with stage III breast cancer between 1987 and 1994. All patients had mastectomy and immediate TRAM reconstruction. Thirteen patients received primary systemic therapy, 10 patients received postoperative consolidation radiotherapy to the operative site, and 3 patients received preoperative radiation.

RESULTS

Mean follow-up for the group was 26 months. Two patients died with disseminated disease: neither of them developed local disease recurrence in the operative site; 82% of the patients followed for at least two years are free of disease. Sixty-two percent of the patients received preoperative chemotherapy, the remaining patients received postoperative multiagent chemotherapy and/or radiation therapy. Two of the patients received autologous bone marrow transplants after their adjuvant therapy. Ten patients had postoperative radiotherapy for consolidation; three patients received preoperative radiation.

CONCLUSIONS

Immediate TRAM reconstruction for stage III breast cancer is not associated with a delay in adjuvant therapy or an increased risk of local relapse. It facilitates wide resection of involved skin without skin grafting. Radiation therapy can be delivered to the reconstructed breast when indicated without difficulty. Breast reconstruction facilitates surgical resection of stage III breast cancer with primary closure and should be considered if the patient desires immediate breast reconstruction.

Tissue-specific posttranslational modification of the small heat shock protein HSP27 in Drosophila

Drosophila sHSPs (small heat shock proteins) are expressed in the absence of stress in specific regions of the central nervous system and in gonads of young adults flies. In these two organs, the sHSPs show a cell-specific and developmental stage-specific pattern of expression suggesting distinct regulation and function(s) of each individual sHSP (R. Marin et al., Dev. Genet. 14, 69-77, 1993). Since mammalian HSP27 has been reported to be phosphorylated through a complex novel cascade implicating distinct kinases, we examined whether two of the sHSPs (HSP27 and HSP23) exist in different isoforms as a result of posttranslational modification in vivo. HSP27 and HSP23 were analyzed in various tissues in unstressed and heat-shocked flies. Four isoforms of HSP27 were found to be constitutively expressed in the nervous system and in testes and two in ovaries. The proportion of these isoforms relative to each other was specific to a given tissue. In the case of HSP23, two isoforms were expressed in the heads and in testes of unstressed flies. In ovaries, a low level of a single isoform of HSP23 was found. Heat shock caused an increase in the amount of preexisting HSP27 and HSP23 and the appearance of additional isoforms in ovaries. Susceptibility to phosphatase treatment indicated that isoforms of HSP27 were phosphoproteins. This was further supported by in vitro experiments in which Drosophila sHSPs were incubated with purified Chinese hamster HSP27 kinase. Only HSP27 was shown to be a substrate of this mammalian HSP27 kinase. The present data suggest that tissue- and HSP-specific posttranslational modification systems may modulate the function of these proteins in different cell types. Furthermore, the signal transduction pathways leading to phosphorylation of the sHSPs are conserved between mammals and Drosophila, and the sHSP kinase cascade may be developmentally regulated.

HSP27 phosphorylation-mediated resistance against actin fragmentation and cell death induced by oxidative stress

Phosphorylation of heat shock protein 27 (HSP27) has been suggested to play an important role in the regulation of F-actin dynamics in response to growth factors and stress. Because the microfilament network is one of the earliest targets of oxidative stress and because phosphorylation of HSP27 is strongly induced by reactive oxygen metabolites, we have investigated the role of HSP27 phosphorylation in regulating actin dynamics in response to oxidative stress. Experiments were done in Chinese hamster CCL39 cells overexpressing various levels of the wild-type or a nonphosphorylatable form of human HSP27 (pm3 HSP27). In control cells, both H2O2 and menadione induced fragmentation of F-actin, which forms aggregates and patches concentrated around the nucleus. Stable overexpression of wild-type HSP27, but not of pm3 HSP27, conferred resistance against actin fragmentation, suggesting that HSP27 has a phosphorylation-activated protective function against actin disruption by oxidative stress. Cell lines that overexpressed the highest levels of the wild-type form of human HSP27 also showed an increased cell survival following exposure to H2O2. In contrast, cells expressing pm3 HSP27 were as sensitive as the controls to the lethal effect of H2O2. These results suggest that phosphorylation of HSP27 is causally related to the regulation of microfilament dynamics following oxidative stress and may be involved in mediating an adaptive response to oxyradical-generating agents such as carcinogens, anticancer drugs, and other xenobiotics.

Tryptophan content of foods and feeds. Conditions for a reliable quantitation

A procedure for the quantitative determination of tryptophan from complex material was developed. It involved the hydrolysis of samples in the presence of baryta. Data were presented, revealing its quantitativeness and pointing out its efficiency when it was compared with diverse methods developed by other laboratories as a part of collaborative studies. The influence of the way of treating and heating of (sample+baryta) mixture upon tryptophan recovery was also investigated. The placement of (sample+baryta) mixture in an autoclave, when water was boiling, or the careful deaeration of the mixture when it was heated in an oven was essential for quantitative results. These specific conditions can be explained by differences of the protein solvatation, related to the way by which the (sample+baryta) mixture was heated.

The tryptophan content in protein of cereal grains and legume seeds as a function of nitrogen content. A reappraisal of tryptophan score

The tryptophan content ([Trp]) in the dry matter (DM) of wheat, maize, barley, sorghum, rice, pearl millet grains, pea and broad bean seeds is evaluated from samples, with various nitrogen contents ([N]DM) and genotypes, using a procedure that has been shown to be strictly quantitative. The determination of linear correlations between [Trp]DM and [N]DM, and between the tryptophan content in protein ([Trp]N) and [N]DM or 1/[N]DM for every species leads to the following observations: (1) [Trp]DM and [N]DM are linearly related. The data show that previous reports of similar relationships underestimate tryptophan by 10 +/- 5% owing to tryptophan degradation during alkaline hydrolysis preparatory to analysis; (2) the linear correlations between [Trp]N and 1/[N]DM, resulting from linear relationships [Trp]DM and [N]DM display coefficients of determination (r2) far lower than 1 and similar to those found for linear correlations between [Trp]N and [N]DM; (3) [Trp]N increases with [N]DM increasing for rice and pearl millet while it decreases for all other species.

IN CONCLUSION

(1) linear relationships between tryptophan and nitrogen have a low predictive value; (2) the nutritional score of tryptophan of foods and feeds, as calculated from the determination of tryptophan using a procedure involving alkaline hydrolysis, is generally underestimated by 10%.

Modulation of actin dynamics during stress and physiological stimulation by a signaling pathway involving p38 MAP kinase and heat-shock protein 27

HSP27, like other proteins of the heat-shock protein family, accumulates to high levels after exposure of cells to a short period of hyperthermia and contributes to the development of a transient state of thermoresistance. In vitro, HSP27 behaves as an actin cap-binding protein and can inhibit actin polymerization. In vivo, the protective function of HSP27 is exerted mainly at the level of the microfilaments and appears as an extension of a normal function of the protein. This function is regulated by phosphorylation in a mitogen- and stress-sensitive signaling pathway involving the newly characterized p38 MAP kinase. The phosphorylation-modulated function of HSP27 can contribute to agonist-induced reorganization of the actin cytoskeleton and, in the case of stress activation, provides an actin-based adaptive response of cells to the new environmental conditions.

TRAM flap breast reconstruction after radiation treatment

OBJECTIVE

Patients with and without radiation treatment before their breast reconstruction were compared to study the relationship of radiation to flap-related complications.

SUMMARY BACKGROUND DATA

The transverse rectus abdominis muscle (TRAM) flap for breast reconstruction involves a a vascular pedicle and recipient bed, both included in the radiated field of patients undergoing adjunctive therapy. Detailed reviews of flap-related complications in this subgroup of patients have been limited.

METHODS

One hundred eight patients with radiation treatment who subsequently underwent a TRAM flap breast reconstruction were compared with 572 patients with no radiation treatment before similar reconstruction. Flap-related complications, radiation dosage, time, fields, relationships between risk factors, and complications were studied.

RESULTS

Overall complication rates were comparable between the two groups. Only fat necrosis (> 10% of total reconstruction) was found to be statistically significant (17.6% vs. 10.1%, p = 0.03228). No difference was found for fat necrosis in unipedicled vs. bipedicled flaps controlled for radiation (17.7% vs. 17.4%). Obesity and radiation therapy were associated with fat necrosis and major infection in a logistic regression. Significant abdominal scarring was also associated with major infection (p = 0.0044).

CONCLUSIONS

In this, the largest reported series, radiation therapy was associated with increased fat necrosis and major infection. The use of the TRAM flap was not found to be prohibitive in radiated patients and should still be the first choice in this subgroup of patients.

Characterization of 45-kDa/54-kDa HSP27 kinase, a stress-sensitive kinase which may activate the phosphorylation-dependent protective function of mammalian 27-kDa heat-shock protein HSP27

Heat-shock protein 27 (HSP27) is a major target of phosphorylation upon cell stimulation with a variety of agents and has been suggested to have a phosphorylation-regulated function at the level of actin filaments. Here we investigated comparatively the mechanisms of HSP27 phosphorylation by oxidative stresses, exposures to tumor necrosis factor (TNF), heat shock and growth factors. Extracts of Chinese hamster or human cells exposed to H2O2, xanthine/xanthine oxidase, menadione or TNF contained up to 15-fold more HSP27 kinase activity than comparable extracts obtained from control cells. Induction of HSP27 kinase activity by TNF or H2O2 was completely inhibited by first treating the cells with the antioxidant N-acetyl-L-cysteine, suggesting that generation of reactive oxygen metabolites was the key triggering element of this induction. In contrast, prior treatment with acetylcysteine had no or little effect on the induction by thrombin, serum and heat shock. The kinase activity in extracts of cells stimulated by heat shock, H2O2, sodium arsenite, TNF or growth factors was identified by in-gel renaturation and purified approximately 8000-fold by sequential chromatography. In all cases, the induced kinase activity was entirely associated with two polypeptides of 45 kDa and 54 kDa, identified as mitogen-activated-protein kinase-activated protein (MAPKAP) kinase-2 based on its reactivation in vitro by 42/44-kDa MAP kinases, its antigenic properties and its substrate specificity. The 45/54-kDa HSP27 kinase may play an important role in the cell response to oxidative stress. Overexpression of the wild-type HSP27 but not of a nonphosphorylatable form of human HSP27 in Chinese hamster cells conferred resistance to actin fragmentation by oxidative stress generated by H2O2. It is concluded that activation of the 45/54-kDa HSP27 kinase is a common mechanism of HSP27 phosphorylation to which converge both oxyradical-dependent and oxyradical-independent pathways and which may participate in a homeostatic response to stress at the level of actin microfilament.

Prognostic significance of heat-shock protein-27 in node-positive breast carcinoma: an immunohistochemical study

Immunostaining for heat-shock protein-27 (HSP-27) was performed on formalin fixed-paraffin embedded sections of 890 node-positive breast carcinomas resected between 1980 and 1986. The follow-up ranged from 2.5 to 10.5 years. A polyclonal antibody (Hu27, dilution: 1/200) was used. A positive cytoplasmic staining was obtained in 383 cases (43%). No difference in distant metastasis-free survival (DMFS) or overall survival (OS) was noted between cases with positive or negative immunostaining. This study suggests that HSP-27 expression is not predictive of the outcome in node-positive breast cancer.

Modulation of cellular thermoresistance and actin filament stability accompanies phosphorylation-induced changes in the oligomeric structure of heat shock protein 27

Phosphorylation of heat shock protein 27 (HSP27) can modulate actin filament dynamics in response to growth factors. During heat shock, HSP27 is phosphorylated at the same sites and by the same protein kinase as during mitogenic stimulation. This suggests that the same function of the protein may be activated during growth factor stimulation and the stress response. To determine the role of HSP27 phosphorylation in the heat shock response, several stable Chinese hamster cell lines that constitutively express various levels of the wild-type HSP27 (HU27 cells) or a nonphosphorylatable form of human HSP27 (HU27pm3 cells) were developed. In contrast to HU27 cells, which showed increased survival after heat shock, HU27pm3 cells showed only slightly enhanced survival. Evidence is presented that stabilization of microfilaments is a major target of the protective function of HSP27. In the HU27pm3 cells, the microfilaments were thermosensitized compared with those in the control cells, whereas wild-type HSP27 caused an increased stability of these structures in HU27 cells. HU27 but not HU27pm3 cells were highly resistant to cytochalasin D treatment compared with control cells. Moreover, in cells treated with cytochalasin D, wild-type HSP27 but not the phosphorylated form of HSP27 accelerated the reappearance of actin filaments. The mutations in human HSP27 had no effect on heat shock-induced change in solubility and cellular localization of the protein, indicating that phosphorylation was not involved in these processes. However, induction of HSP27 phosphorylation by stressing agents or mitogens caused a reduction in the multimeric size of the wild-type protein, an effect which was not observed with the mutant protein. We propose that early during stress, phosphorylation-induced conformational changes in the HSP27 oligomers regulate the activity of the protein at the level of microfilament dynamics, resulting in both enhanced stability and accelerated recovery of the filaments. The level of protection provided by HSP27 during heat shock may thus represent the contribution of better maintenance of actin filament integrity to overall cell survival.

Cells overexpressing Hsp27 show accelerated recovery from heat-induced nuclear protein aggregation

Protein denaturation/aggregation upon cell exposure to heat shock is a likely cause of cell death. In the nucleus, protein aggregation has often been correlated to inhibition of nuclear located processes and heat-induced cell killing. In Chinese hamster O23 cells made thermotolerant by a prior heating (20'44 degrees C + 10h 37 degrees C) which induces the whole spectrum of heat shock proteins (hsps), the extent of nuclear protein aggregation during heat shock is reduced and the rate of recovery from aggregation after heat shock is enhanced. In contrast, a heat resistant Chinese hamster cell line overexpressing only hsp27 shows an unaltered sensitivity to formation of nuclear protein aggregates by heat, but shows the same enhanced rate of recovery from nuclear protein aggregation as thermotolerant cells. This suggests that accelerated recovery of protein aggregation could be partly responsible for hsp27-mediated thermoprotection.

Modulation of actin microfilament dynamics and fluid phase pinocytosis by phosphorylation of heat shock protein 27

We recently reported that overexpression of heat shock protein 27 (HSP27) in rodent fibroblasts increases the stability of stress fibers during hyperthermia and partially prevents actin depolymerization during exposure to cytochalasin D (Lavoie, J.N., Gingras-Breton, G., Tanguay, R. M., and Landry, J. (1993) J. Biol. Chem. 268, 3420-3429). Because HSP27 is a ubiquitous target of phosphorylation upon cell stimulation with a variety of growth factors and agents that affect cellular differentiation, we examined the role of HSP27 phosphorylation in regulating actin filament dynamics. Here we show that HSP27 is enriched at the leading edge of polarized fibroblasts. HSP27 is localized in lamellipodia and membrane ruffles where most actin polymerization occurs. We developed Chinese hamster cell lines that constitutively overexpressed either human HSP27 or a nonphosphorylatable mutant form of the protein. Overexpression of HSP27 caused an increased concentration of filamentous actin (F-actin) at the cell cortex and elevated pinocytotic activity. In contrast, overexpression of the non-phosphorylatable mutant form of HSP27 reduced cortical F-actin concentration and decreased pinocytosis activity relative to control cells. Mitogenic stimulation of fibroblasts resulted in a rapid polymerization of submembranous actin filaments. HSP27 enhanced growth factor-induced F-actin accumulation, whereas mutant HSP27 exerted a dominant negative effect and inhibited this response to growth factors. Thus, HSP27 is a component of a signal transduction pathway that can regulate microfilament dynamics.

Putative determinants of the cellular response to hyperthermia

Recently, it has been demonstrated that two different thermal resistant states found in Chinese hamster cells, one transient, associated with thermotolerance, and the other permanent, associated with the increased expression of the cognate member of the hsp 70 family, are characterized by faster recovery from heat-induced perturbations in several cellular processes (Laszlo 1992b). These processes include total cellular protein and RNA synthesis, the localization of hsp70, the organization of vimentin, and the protein composition of the nucleus. In the present study, the recovery from heat-induced perturbations in cellular physiology was extended further to two more types of Chinese hamster cells: permanently heat resistant cells in which thermoresistance is associated with the overexpression of hsp27 and heat-sensitive cell lines. When the heat-resistant hsp27 transfected cell lines were compared with the control wild-type cell line, the recovery of protein synthesis from heat-induced inhibition was similar in the normal and hsp27 transfected cells, while the recovery from heat-induced inhibition of total RNA synthesis and the recovery from heat-induced increased association of hsp70 with nuclei were both more rapid in the hsp27 transfected cell lines. In the permanently heat-sensitive cell lines, the kinetics of recovery from heat-induced inhibition of protein synthesis did not correlate with the heat sensitive state. However, delays in the recovery from heat-induced alterations in total cellular RNA synthesis and from heat-induced excess nuclear association of hsp70 were associated with the heat-sensitive state. Overall, these results suggest that the kinetics of recovery from heat-induced alterations in total cellular RNA synthesis and the localization of hsp 70 are putative candidates for being determinants of the cellular response to hyperthermia, and thus have the potential to form the basis of predictive assays for use in conjunction with clinical hyperthermia.

Induction of Chinese hamster HSP27 gene expression in mouse cells confers resistance to heat shock. HSP27 stabilization of the microfilament organization

Heat shock induces in cells the development of a transient state of thermotolerance thought to result from the induction of heat shock proteins. To assess directly whether a transient overexpression of one of these proteins, HSP27, can contribute to increased cellular resistance, mouse NIH/3T3 cells were cotransfected with a plasmid containing the Chinese hamster HSP27 gene under the control of the metallothionein promoter and a plasmid containing the neo gene. Stable transfectant cell lines were selected for resistance to the antibiotic G418. Analyses of several stable transfectant cell lines indicated that expression of Chinese hamster HSP27 could be selectively induced by exposure to 3 microM CdCl2, a concentration that had no effect on the induction of the endogenous heat shock proteins (HSP). In clone 15, the level of HSP27 increased steadily during the first day of exposure to CdCl2, from a concentration of 1 microgram/mg of total protein to 7 micrograms/mg. After withdrawal of CdCl2, the level of HSP27 returned to normal within the next 5 days. Accumulation of the Chinese hamster HSP27 was accompanied by a progressive development of thermoresistance that attained a level approaching heat shock-induced thermotolerance. After CdCl2 removal, thermal resistance and HSP27 decayed in a coordinated manner. In control cells transfected with the neo gene only, increased thermoresistance was not induced by 3 microM CdCl2; in these cells, an exposure to 20 microM CdCl2 was required to induce a level of thermoresistance comparable to that induced by 3 microM CdCl2 in clone 15. Elevated expression of HSP27 was accompanied by an increased stability of stress fibers during hyperthermia. The protein also partially prevented actin depolymerization during acute exposure to cytochalasin D and reduced cytotoxicity and growth inhibition of chronic exposures to the drug. The results indicated that accumulation of HSP27, as it occurs after a mild heat shock or other inducing treatments, is sufficient for acquisition of thermotolerance that may result in part from a stabilization of actin filaments.