Relationship of HSP27 and oestrogen receptor in hormone sensitive and insensitive cell lines

Cluster analyses of the TCGA and a TMA dataset using the coexpression of HSP27 and CRYAB improves alignment with clinical-pathological parameters of breast cancer and suggests different epichaperome influences for each sHSP

Our cluster analysis of the Cancer Genome Atlas for co-expression of HSP27 and CRYAB in breast cancer patients identified three patient groups based on their expression level combination (high HSP27 + low CRYAB; low HSP27 + high CRYAB; similar HSP27 + CRYAB). Our analyses also suggest that there is a statistically significant inverse relationship between HSP27 and CRYAB and known clinicopathological markers in breast cancer. Screening an unbiased 248 breast cancer patient tissue microarray (TMA) for the protein expression of HSP27 and phosphorylated HSP27 (HSP27-82pS) with CRYAB also identified three patient groups based on HSP27 and CRYAB expression levels. TMA24 also had recorded clinical-pathological parameters, such as ER and PR receptor status, patient survival, and TP53 mutation status. High HSP27 protein levels were significant with ER and PR expression. HSP27-82pS associated with the best patient survival (Log Rank test). High CRYAB expression in combination with wild-type TP53 was significant for patient survival, but a different patient outcome was observed when mutant TP53 was combined with high CRYAB expression. Our data suggest that HSP27 and CRYAB have different epichaperome influences in breast cancer, but more importantly evidence the value of a cluster analysis that considers their coexpression. Our approach can deliver convergence for archival datasets as well as those from recent treatment and patient cohorts and can align HSP27 and CRYAB expression to important clinical-pathological features of breast cancer.

Up-regulation of Hsp27 by ERα/Sp1 facilitates proliferation and confers resistance to apoptosis in human papillary thyroid cancer cells

17β-estradiol (E2) has been suggested to play a role in the development and progression of papillary thyroid cancer. Heat shock protein 27 (Hsp27) is a member of the Hsp family that is responsible for cell survival under stressful conditions. Previous studies have shown that the 5'-promoter region of Hsp27 gene contains a specificity protein-1 (Spl) and estrogen response element half-site (ERE-half), which contributes to Hsp27 induction by E2 in breast cancer cells. However, it is unclear whether Hsp27 can be up-regulated by E2 and which estrogen receptor (ER) isoform and tethered transcription factor are involved in this regulation in papillary thyroid cancer cells. In the present study, we demonstrated that Hsp27 can be effectively up-regulated by E2 at mRNA and protein levels in human K1 and BCPAP papillary thyroid cancer cells which have more than two times higher level of ERα than that of ERβ. The up-regulation of Hsp27 by E2 is mediated by ERα/Sp1 and ERβ has repressive effect on this ERα/Sp1-mediated up-regulation of Hsp27. Moreover, we showed that the up-regulation of Hsp27 by ERα/Sp1 facilitates proliferation and confers resistance to apoptosis through interaction with procaspase-3. Targeting this pathway may be a potential strategy for therapy of papillary thyroid cancer.

Expression Profiling and Cellular Localization of Stress Responsive Proteins in Squamous Cell Carcinoma of Human Esophagus

BACKGROUND

The ambiguity in relating expression dynamics of stress response proteins with human esophageal squamous cell carcinoma (ESCC) has sidelined the potential of stress proteins as therapeutic targets. This study was an attempt to unequivocally relate the stress protein dynamics with stage and propensity of ESCC.

METHODS

Surgically resected tumor and adjacent histologically normal tissue from 46 patients with esophageal squamous cell carcinoma were investigated in the present study. Expression of HSPs was analyzed by Western blotting and immunohistochemistry.

RESULTS

HSP expression was observed in all 46 cases both in adjacent normal and tumor tissues. The expression and the localization of individual HSP showed no significant correlation with depth of invasion, tumor grade, and pathological stage of the tumor. HSP 27 was the most abundant protein followed by HSP 90 and HSP 70. The HSP 27 localized exclusively in the cytoplasm of adjacent normal and tumor cells. HSP 70 showed dispersed expression with predominating nuclear localization in both normal and tumor tissue cells and HSP 90 was localized in cytoplasm of adjacent normal and in nucleus of tumor cells in majority of the cases.

CONCLUSION

Our data advocate lack of relationship between stress protein expression and the progression of ESCC. The data renew the prospect of anti-HSP drugs as therapeutic resources in light of the possibility that their use would continue to sensitize cancer cells towards drug induced apoptosis for tumor regression.

Hsp27 (HSPB1) differential expression in normal salivary glands and pleomorphic adenomas and association with an increased Bcl2/Bax ratio

Pleomorphic adenoma (PA) is the most common salivary gland neoplasm. The Hsp27 (HSPB1) is an antiapoptotic protein whose synthesis follows cytotoxic stresses and result in a transient increase in tolerance to subsequent cell injury. Although Hsp27 is expressed in a range of normal tissues and neoplasms, a wide variation in its expression exists among different cells and tissues types. In certain tumours of glandular origin (such as oesophageal adenocarcinomas), the level of Hsp27 is decreased. In the present study, Hsp27 protein levels were evaluated by enzyme-linked immunosorbent assay (ELISA) in a set of 18 fresh PA and 12 normal salivary gland samples. In addition, we tested if Hsp27 protein levels correlated with p53 expression and cell proliferation index, as well as with the transcriptional levels of Bcl-2-associated X protein (BAX), B cell lymphoma 2 (BCL2) and Caspase 3 in PA. We further tested the association between Hsp27 expression and PA tumour size. While all normal salivary gland samples expressed Hsp27 protein, only half of the PA samples expressed it, resulting in a reduced expression of Hsp27 in PA when compared with normal salivary glands (P = 0.003). The expression levels of this protein correlated positively with a higher messenger ribonucleic acid (mRNA) ratio of Bcl2/Bax (R = 0.631; P = 0.01). In conclusion, a decreased Hsp27 protein expression level in PA was found. In addition, Hsp27 levels correlated positively with the Bcl2/Bax mRNA ratio, suggesting an antiapoptotic effect.

Small heat shock protein expression and functions during development

The expression of small heat shock proteins is tightly regulated during development in multiple organisms. As housekeeping proteins, small heat shock proteins help protect cells from apoptosis, stabilize the cytoskeleton and contribute to proteostasis. Consistently, depletion of one small heat shock protein is usually not detrimental due to a certain level of redundancy between the functions of each small heat shock protein. However, while their stress-induced expression is regulated by heat shock factors, their constitutive expression is under the control of other specific transcription factors, suggesting the existence of very specialized functions. This review focuses on the expression patterns and functions of small heat shock proteins in various organisms during development. This article is part of a Directed Issue entitled: Small HSPs in physiology and pathology.

Altered expression of HSP27 and HSP70 in distal oesophageal mucosa in patients with gastro-oesophageal reflux disease subjected to fundoplication

BACKGROUND

Gastro-oesophageal reflux disease (GERD) is a risk factor for oesophageal adenocarcinoma. Although fundoplication cures reflux symptoms and oesophagitis, it remains controversial whether it is capable of preventing the development of oesophageal adenocarcinoma. Hsp27 and Hsp70 are associated with the development of cancer, whereas the effect of fundoplication on them is not known.

METHODS

The expression of Hsp27 and Hsp70 was assessed semiquantitatively from biopsies of oesophageal mucosa for a prospective cohort of 19 patients with GERD treated with fundoplication and 7 controls without GERD. Upper gastrointestinal endoscopy with biopsies from the oesophagogastric junction (EGJ) and the distal and proximal oesophagus were performed preoperatively (19 patients) and after recovery from GERD at 6 (19 patients) and 48 months (16 patients) postoperatively.

RESULTS

The expressions of both Hsp27 (p = 0.001) and Hsp70 (p = 0.002) in the distal oesophagus were lower in patients preoperatively and at 48 months postoperatively (p < 0.001 for both) than in controls. The patients' Hsp27 and Hsp70 levels were lower preoperatively in the proximal oesophagus (p = 0.048 for both) than in controls. Both Hsp27 (p = 0.002) and Hsp70 (p = 0.003) were lower in the distal oesophagus preoperatively and at 48 months postoperatively (p = 0.003 for Hsp27, p = 0.004 for Hsp70) than in the proximal oesophagus.

CONCLUSIONS

Our results indicate that there may be some factor interfering with the mucosal defence system of the distal oesophagus in GERD that is uninfluenced by fundoplication and not associated with the acid-reflux-normalizing effect.

The level of Hsp27 in lymphocytes is negatively associated with a higher risk of lung cancer

Heat shock proteins (Hsps) can protect cells, organs, and whole organisms against damage caused by abnormal environmental hazards. Some studies have reported that lymphocyte Hsps may serve as biomarkers for evaluating disease status and exposure to environmental stresses; however, few epidemiologic studies have examined the associations between lymphocyte Hsps levels and lung cancer risk. We examined lymphocyte levels of Hsp27 and Hsp70 in 263 lung cancer cases and age- and gender-matched cancer-free controls by flow cytometry. Multivariate logistic regression models were used to estimate the association between lymphocyte Hsps levels and lung cancer risk. Our results showed that Hsp27 levels were significantly lower in lung cancer cases than in controls (16.5 vs 17.8 mean fluorescence intensity, P < 0.001). This was not observed for Hsp70 levels. Further stratification analysis revealed that lymphocyte Hsp27 levels were negatively associated with lung cancer risk especially in males and heavy smokers. There was a statistical trend of low odd ratios (95% confidence intervals) and upper tertile levels of Hsp27 [1.000, 0.904 (0.566-1.444) and 0.382 (0.221-0.658, P (trend) = 0.001) in males and 1.000, 0.9207 (0.465-1.822) and 0.419 (0.195-0.897, P (trend) = 0.036) in heavy smokers] after adjustment for confounding factors. These results suggest that lower lymphocyte Hsp27 levels might be associated with an increased risk of lung cancer. Our findings need to be validated in a large prospective study.

Control of estradiol-directed gene transactivation by an intracellular estrogen-binding protein and an estrogen response element-binding protein

New World primates exhibit a form of resistance to estrogens that is associated with overexpression of an estrogen response element (ERE)-binding protein (ERE-BP) and an intracellular estradiol (E(2))-binding protein (IEBP). Both proteins suppress E(2)-mediated transcription when overexpressed in estrogen receptor-alpha (ERalpha)-positive cells. Although ERE-BP acts as a competitor for ERE occupancy by liganded ERalpha, the function of IEBP and its human homolog, heat-shock protein 27 (hsp27), is less clear. In data presented here, we have used E(2)-responsive human MCF-7 breast cancer cells to show that IEBP/hsp27 can regulate estrogen signaling as a cytosolic decoy for E(2) and as a protein chaperone for ERalpha. Furthermore, co-immunoprecipitation, colocalization, yeast two-hybrid, and glutathione S-transferase pull-down analyses indicate that IEBP/hsp27 also interacts with ERE-BP to form a dynamic complex that appears to cycle between the cytoplasm and nucleus during normal estrogen signaling. Overexpression of either IEBP/hsp27 or ERE-BP in MCF-7 cells resulted in abnormal subcellular distribution of the IEBP/hsp27 and ERE-BP, with concomitant dysregulation of ERE occupancy as determined by chromatin immunoprecipitation. We hypothesize that IEBP/hsp27 and ERE-BP not only cause hormone resistance in New World primates but are also crucial to normal estrogen signaling in human cells. This appears to involve a physical association between the two proteins to form a complex that is able to interact with both E(2) and ERalpha in cytosolic and nuclear compartments.

Expression of the Brn-3b Transcription Factor Correlates with Expression of HSP-27 in Breast Cancer Biopsies and Is Required for Maximal Activation of the HSP-27 Promoter

In breast cancer, overexpression of the small heat shock protein, HSP-27, is associated with increased anchorage-independent growth, increased invasiveness, and resistance to chemotherapeutic drugs and is associated with poor prognosis and reduced disease-free survival. Therefore, factors that increase the expression of HSP-27 in breast cancer are likely to affect the prognosis and outcome of treatment. In this study, we show a strong correlation between elevated levels of the Brn-3b POU transcription factor and high levels of HSP-27 protein in manipulated MCF-7 breast cancer cells as well as in human breast biopsies. Conversely, HSP-27 is decreased on loss of Brn-3b. In cotransfection assays, Brn-3b can strongly transactivate the HSP-27 promoter, supporting a role for direct regulation of HSP-27 expression. Brn-3b also cooperates with the estrogen receptor (ER) to facilitate maximal stimulation of the HSP-27 promoter, with significantly enhanced activity of this promoter observed on coexpression of Brn-3b and ER compared with either alone. RNA interference and site-directed mutagenesis support the requirement for the Brn-3b binding site on the HSP-27 promoter, which facilitates maximal transactivation either alone or on interaction with the ER. Chromatin immunoprecipitation provides evidence for association of Brn-3b with the HSP-27 promoter in the intact cell. Thus, Brn-3b can, directly and indirectly (via interaction with the ER), activate HSP-27 expression, and this may represent one mechanism by which Brn-3b mediates its effects in breast cancer cells.

Immunolocalization of heat shock protein 27 in developing jaw bones and tooth germs of human fetuses

27 kDa Heat shock protein (Hsp27), which is also identified as p29 estrogen-receptor associated protein, plays a crucial role in specific growth stages. It also seems to be involved in the balance between differentiation and apoptosis. To determine whether Hsp27 is involved during craniofacial development and odontogenesis, its expression was studied through immunohistochemistry of developing jaw bone as well as the odontogenesis of heads from human fetuses. Formalin-fixed paraffin-embedded specimens of 7 human fetuses (3 female, 4 male), obtained from miscarriages occurring between the 9th and 16th weeks of pregnancy, were examined by using a monoclonal antibody against Hsp27. Staining intensity (weak, +; moderate, ++; strong, +++) was evaluated semiquantitatively. The sample slice was cut through a coronal plane, which included eyes, nasal cavities, tongue, and primitive dental lamina with tooth germs. A transient and spatially restricted expression of Hsp27 in developing human jaw bones and teeth was observed. Osteoblasts around the uncalcified bone matrix showed Hsp27 immunoreaction products (+++), whereas osteocytes were not immunolabeled. In mandibular condyle, immunolabeling was restricted to hypertrophic chondrocytes (++). In developing tooth germs, Hsp27 immunostaining was detected throughout the bud (+++). At the early cap stage, a strong immunolabeling for Hsp27 was seen in the dental lamina (+++), and a moderate staining was seen in the outer dental epithelium (++). At the late cap stage, Hsp27 expression was detected in the outer dental epithelium (++) as well as in the cells of the future stellate reticulum (++). The spatiotemporal-restricted expression of Hsp27 in craniofacial bones during development suggests that this protein could be involved in the balance between differentiation and apoptosis, by modulating the viability of osteoblasts and chondrocytes. The specific regional and temporal expression patterns of Hsp27 during tooth development sustains that this small Hsp might be related to the morphogenesis and cytodifferentiation processes of tooth germs.

Gene expression profile in the livers of rats orally administered ethinylestradiol for 28 days using a microarray technique

To identify genes showing responses to estrogen exposure in the livers of animals in a repeated oral dose toxicity study, dose-dependent gene expression profiles were analyzed using high-density oligonucleotide microarrays in Sprague-Dawley rats of both sexes administered ethinylestradiol (EE) for 28 days at concentrations of 0, 0.01, 0.1, and 1.0 ppm in the diet. Among 3776 genes examined, examples showing increased expression on EE-treatment were detected predominantly in females. Genes showing dose-dependent up-regulation with greater than five-fold change at 1.0 ppm from the control levels were found to, respectively, number 4 in males, and 24 in females. Most of the latter exhibited relatively high basal expression as well as low variability, and many exhibited clear dose-dependence. Genes showing dose-dependent down-regulation were rather few, and many of those affected exhibited relatively low expression levels with large variation between animals, like genes showing dose-unrelated expression patterns in both sexes or dose-dependent up-regulation in males. Considering that detection of changes in endocrine-linked organs and estrous cyclicity is only possible at the high dose of 1.0 ppm, up-regulation of genes dose-dependently in females provides a sensitive tool to detect estrogenic effects in the rat liver in the framework of the 28-day toxicity study.

In vivo bone metastases, osteoclastogenic ability, and phenotypic characterization of human breast cancer cells

Mouse bone marrow cells cultured with human breast cancer MCF-7 cell-conditioned media showed osteoclastogenesis with an increment of bone resorption, although conditioned media from an adriamycin-selected MCF-7 clone (MCF-7ADR) had no effect. Consistently, MCF-7 cells induced 5-fold more in vivo experimental osteolytic bone metastases, with no soft tissue lesions, compared to MCF-7ADR cells. Paracrine factors stimulating (interleukin (IL)-6, IL-1beta, tumor necrosis factor-alpha (TNF-alpha)) or inhibiting (IL-12, IL-18, granulocyte macrophage-colony stimulating factor (GM-CSF)) osteoclastogenesis were significantly increased in MCF-7ADR relative to MCF-7 cells, suggesting that the inhibitory cytokines could selectively overwhelm the effects of the stimulatory ones. Treatment of osteoblast primary cultures with MCF-7-conditioned medium induced a selective upregulation of IL-6 expression, suggesting an indirect stimulation of osteoclastogenesis via the osteoblasts. MCF-7 and MCF-7ADR showed no difference in proliferation rate. However, a higher ability to migrate and invade gelatin and matrigel was observed in MCF-7ADR. Enhanced invasiveness might result from increased metalloproteinase (MMP) activity and cytoskeleton rearrangement. MCF-7ADR cells expressed higher levels of c-Src, focal adhesion kinase (FAK), and protein tyrosine kinase 2 (PYK2) involved in cell adhesion and motility. MCF-7 and MCF-7ADR expressed high and faint levels of functional estrogen receptor alpha (ERalpha), respectively. MCF-7ADR also showed significantly higher levels of the protein kinase C (PKC) alpha and beta2 and a selective activation of PKC compared to MCF-7, where the most abundant isoforms were beta1 and delta. Heat shock protein 27 (Hsp27) was more abundant in MCF-7 cells, but failed to translocate to the nucleus in response to heat shock. In conclusion, we have demonstrated that despite the fact that MCF-7ADR cells showed a more invasive phenotype relative to MCF-7, they have low potential to induce osteolytic bone lesions and stimulate osteoclastogenesis and osteoclast activity. Therefore, we believe that reduced aggressiveness of breast carcinomas could correlate with a greater osteolytic activity featuring their bone metastases.

Clinicopathological study of the expression of hsp27, pS2, cathepsin D and metallothionein in primary invasive breast cancer

Expression of the hormone-related proteins hsp27, pS2, and also of cathepsin D (CD) and metallothionein (MT) was studied by immunohistochemistry and analyzed against clinical data in breast cancer. Archived material of paraffin-embedded breast carcinoma tissues from a cohort of 134 patients with primary invasive breast cancer was used. Hsp27 and pS2 (>10% of tumor cells stained) were found to be expressed in 63.6% and 37.6% of cases, respectively, and were correlated negatively with grading (P=0.006 and 0.01) and positively with estrogen receptors (ER) (P=0.04 and 0.04). pS2 expression was correlated with lymph node status (P=0.02), tumor size (P=0.01), progesterone receptor (PR) content (P=0.02), hsp27 (P=0.015) and bcl-2 protein (P=0.001). An inverse relationship between pS2 expression and the expression of p53 protein (P=0.005) and proliferation-associated index MIB1 (P<0.0001) was noted. Stromal cathepsin D was positively correlated with tumor grade (P=0.01), PCNA (P=0.007), MIB1 (P=0.001) and p53 (P=0.01), and negatively with ER (P=0.04) and bcl-2 (P<0.0001). MT was correlated positively with stromal CD (P=0.007) and inversely with PgR (P=0.04). Univariate analysis showed CD expression to be a positive prognostic factor for survival (P=0.035), with borderline significance, while MT was more strongly positive (P=0.01). However, none of the proteins studied was found to be related to disease outcome in univariate analysis. Our data show that hsp27, pS2 and stromal CD expression may reflect tumor differentiation and the functional status of ER in breast cancer, but stromal CD and tumor MT expression were the only factors found that may be of limited prognostic value.

Expression of heat shock protein 27 (HSP27) in human temporomandibular joint discs of patients with internal derangement

Heat shock proteins (HSPs) are believed to represent a cellular stress response mechanism that protects intracellular proteins from damaging events. Some studies have demonstrated an enhanced expression of large-molecular-weight HSPs in diseased systematic joints. Small heat shock proteins, and among these HSP27, have been studied to a lesser extent. HSP27 has cytoprotective and biosynthetic functions within chondrocytes, and it is an estrogen-associated protein that is under hormonal modulation. To improve understanding at a molecular level of the pathophysiology of certain temporomandibular joint disorders, the authors carried out this immunohistochemical study to assess the presence of HSP27 in human TMJ discs. Twelve adult human TMJ discs (10 diseased and 2 healthy discs) and 5 TMJ fetal human discs were used in this study. Adult discs and TMJ tissues of human fetuses were fixed in 10% buffered formalin. Samples were then processed for histologic examination. Sections were immunohistochemically stained using the streptavidin-biotin detection method. No reaction product for HSP27 in the discs of fetuses was noted. HSP27 was weakly expressed in normal TMJ discs and highly up-regulated in discs of patients showing new vessel formation and chondroid metaplasia. Any correlation between gender and HSP27 was found in the sample, being the up-regulation of HSP27 related mostly to major histopathological changes. This different pattern of HSP27 immunostaining in human TMJ discs detected in the authors' specimens suggests that the expression of this small HSP is functionally modulated. In fact HSP27 up-regulates in internal derangement specimens with major histopathological changes; on the other hand, it is not expressed or only weakly expressed in TMJ discs of fetuses and normal TMJ discs.

Target-Directed Enediynes: Designed Estramycins

The goal of selective targeting of enediyne cytotoxins has been investigated using estrogenic delivery vehicles. A series of estrogen-enediyne conjugates were assembled, and affinity for human estrogen receptor [hERalpha] was determined. The most promising candidate induced receptor degradation following Bergman cycloaromatization and caused inhibition of estrogen-induced transcription in T47-D human breast cancer cells.

Estrogen receptor gene expression and its relation to the estrogen-inducible HSP27 heat shock protein in hormone refractory prostate cancer

BACKGROUND

The recent discovery of the classical estrogen receptor alpha (ERalpha) in androgen-insensitive prostate cancer has shed new light on the role of estrogens in endocrine therapy failure. To get more information on downstream events of estrogen signaling in these tumors, we investigated the relation between ERalpha gene expression, and the estrogen-inducible heat shock protein HSP27 in recurrent prostatic adenocarcinomas.

METHODS

Palliative transurethral resection specimens from 50 patients with androgen-insensitive disease were submitted for study. Messenger RNA in situ hybridization for the ERalpha and immunohistochemistry of the HSP27 protein were performed on adjacent sections of an equal number of prostate cancer tissue with and without ERalpha protein expression.

RESULTS

Cancerous lesions lacking the nuclear ERalpha at the protein level revealed ERalpha mRNA expression in 15 of 25 cases (60%). A coordinate expression of ERalpha mRNA and HSP27 was observed in 33 of 40 cases (83%), although a significant correlation between ERalpha protein and HSP27 expression was not obtained. Conversely, 90% of neoplastic lesions without detectable levels of ERalpha mRNA and protein also lacked HSP27 immunoreactivity.

CONCLUSIONS

ERalpha gene expression at the mRNA level significantly correlated with the immunoprofile of the estrogen-inducible HSP27 protein in androgen-insensitive prostatic adenocarcinomas. This may indicate that these tumors harbor functional active estrogen receptors promoting transcriptional activity of the HSP27 gene. Determination of the receptor status by immunohistochemistry is unable to identify neoplastic lesions with established ERalpha mRNA expression in a substantial number of cases. HSP27 may be an additional surrogate biomarker for estrogen-regulated growth in androgen-insensitive prostate cancer.

Intermediate filament interactions can be altered by HSP27 and alphaB-crystallin

HSP27 and alphaB-crystallin are both members of the small heat shock protein family. alphaB-crystalllin has been proposed to modulate intermediate filaments and recently a mutation in alphaB-crystallin has been identified as the genetic basis of desmin related myopathy. This disease is characterised in its pathology by aggregates of intermediate filaments associated with alphaB-crystallin. Here we report that HSP27 like alphaB-crystallin is associated with glial fibrillary acidic protein and vimentin intermediate filament networks in unstressed U373MG astrocytoma cells. HSP27 is also associated with keratin filaments in MCF7 cells, indicating that this association is not restricted to a particular intermediate filament type. The association of sHSPs with both the soluble and filamentous intermediate filament fractions of U373 cells was demonstrated biochemically. Heat shock or drug treatments induced a co-collapse of intermediate filaments and associated small heat shock proteins. These data show that the presence of HSP27 or alphaB-crystallin could not prevent filament collapse and suggest that the purpose of this association is more than just filament binding. Indeed, in U373MG cells the intermediate filament association with small heat shock proteins is similar to that observed for another protein chaperone, HSC70. In order to discern the effect of different chaperone classes on intermediate filament network formation and maintenance, several in vitro assays were assessed. Of these, falling ball viscometry revealed a specific activity of small heat shock proteins compared to HSC70 that was apparently inactive in this assay. Intermediate filaments form a gel in the absence of small heat shock proteins. In contrast, inclusion of alphaB-crystallin or HSP27 prevented gel formation but not filament assembly. The transient transfection of GFAP into MCF7 cells was used to show that the induction of a completely separate network of intermediate filaments resulted in the specific association of the endogenous HSP27 with these new GFAP filaments. These data lead us to propose that one of the major functions of the association of small heat shock proteins with intermediate filaments is to help manage the interactions that occur between filaments in their cellular networks. This is achieved by protecting filaments against those non-covalent interactions that result when they come into very close proximity as seen from the viscosity experiments and which have the potential to induce intermediate filament aggregation as seen in some disease pathologies.

Differential expression of Hsp27 in normal oesophagus, Barrett's metaplasia and oesophageal adenocarcinomas

The protein expression patterns of normal, metaplastic and malignant oesophageal tissues were analysed by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) to identify changes associated with Barrett's metaplasia and transformation to oesophageal adenocarcinoma. Heat-shock protein 27 (Hsp27), a small heat-shock protein which is protective against cytotoxic stresses, was abundant in normal oesophagus. However, Hsp27 expression was markedly lower in Barrett's metaplasia and oesophageal adenocarcinomas. This was confirmed by immunohistochemical analysis. Hsp27 protein was most highly expressed in the upper layers of squamous epithelium and exhibited a pattern of expression that corresponded with the degree of squamous maturation. Northern and Southern analysis demonstrated Hsp27 to be regulated at the level of mRNA transcription or abundance. Normal oesophageal tissues were examined for gender differences in Hsp27 expression. Women expressed fourfold higher levels of Hsp27 mRNA, however, this difference was not appreciable in protein expression. Hsp27 protein was inducible by heat shock in Barrett's adenocarcinoma cell lines and an immortalized oesophageal epithelial cell line (HET-1A), but not by oestradiol. These results demonstrate abundant constitutive expression of the stress-response protein Hsp27 in the normal oesophagus, and suggest that low-level expression in Barrett's metaplasia may be one factor which may influence susceptibility to oesophageal adenocarcinoma development.

Differential localization of heat shock proteins 90, 70, 60 and 27 in human decidua and placenta during pregnancy

Little is known about the localization of heat shock proteins (HSPs) in the decidua and placenta during the course of normal pregnancy. In this study, we have examined the localization of the HSPs in decidual and placental tissues obtained from women during the first, second and third trimesters of pregnancy (five in each trimester) by immunohistochemistry using highly specific antisera. HSPs 90, 70, 60 and 27 were detected in decidual stromal cells during each trimester. The intensity of staining did not change during gestation for HSPs 60 and 27, whereas it decreased with advancing gestation for HSPs 90 and 70. HSPs 90 and 60 were localized primarily in the nucleus, whereas HSP 70 was present equally in the nucleus and the cytoplasm; HSP 27 was primarily in the cytoplasm. In the placenta, HSPs 90, 70 and 60 were localized in cytotrophoblast, syncytiotrophoblast, intermediate trophoblast, Hofbauer and endothelial cells. HSPs 90 and 60 were localized primarily in the nucleus, while HSP 70 was in the nucleus and the cytoplasm. In the placenta, HSP 27 was detected only in the intermediate trophoblast and syncytiotrophoblast cells and only in the first two trimesters. These results indicate that there are striking differences in the subcellular localization of HSPs in the decidua and the placenta during normal pregnancy.

Steroid hormones and cancer: (III) observations from human subjects

Epidemiological evidence strongly suggests that steroid hormones are implicated in the risk of cancers of the breast, ovary and endometrium. However, it has proved difficult to implicate specific hormones or show that measurement of circulating hormones can identify women who will go on to develop malignant disease. There are, however, more convincing data that a proportion of established cancers are dependent upon steroid hormones for their continued growth and these underpin the use of endocrine manoeuvres in the treatment of these malignancies. Increased knowledge of the synthesis, release and mechanism of action of steroid hormones has led to the development of novel therapies for endocrine sensitive cancer and on-going research can reasonably be expected to identify tumour markers which can accurately predict hormone-dependency and provide better understanding of the mechanism by which response and resistance to therapy occur. The hope is that this knowledge will translate into more effective and rational endocrine treatment benefiting increased numbers of patients.

Lack of relationship between the expression of Hsp27 heat shock estrogen receptor-associated protein and estrogen receptor or progesterone receptor status in male breast carcinoma

Estrogen, through estrogen receptors (ERs), may regulate the synthesis of progesterone receptors (PRs) and of a heat shock estrogen receptor-associated protein (hsp27). In female breast carcinoma (FBC) both proteins serve as surrogate indicators for the presence of functional ERs. In addition, the expression of these proteins was related to other prognostic indicators of value in female breast tumours. Endocrine disorders, hormone therapy and altered estrogen metabolism have been associated with the development of male breast cancer (MBC), suggesting that evaluation of the expression of ER, PR and hsp27 might improve our understanding of the biology of this tumour. ER and PR status and hsp27 expression were evaluated by immunohistochemistry in 16 primary MBC patients. The interrelationships between these parameters were established and compared with the clinicopathological data on the tumours. Ten (56%) MBC patients were ER-positive, 69% were PR-positive and all samples were hsp27-positive. Our series of MBC patients showed a positive correlation between ERs and PRs, however there was a lack of correlation between hsp27 and ERs or PRs. MBCs did not exhibit any correlation between the biomarkers studied and known prognostic indicators for females (e.g. Scarff-Bloom-Richardson (SBR) or modified SBR (MSBR) grade, T stage, lymph node status). This is the first published series reporting the incidence of hsp27 in MBC. The lack of association between the expression of ERs and hsp27 found in MBC differs from the results reported for FBC, moreover the expression of ERs, PRs or hsp27 did not correlate with the clinicopathological parameters that have prognostic value in females. Although the data were obtained from a relatively small sample population, our findings suggest that MBC and FBC are biologically different tumours with respect to the expression of the studied proteins.

Differential expression of heat shock protein HSP27 in human neurons and glial cells in culture

HSP27 expression was investigated in cultured neurons and glial cells isolated from fetal human brains using immunoblotting and immunocytochemistry. Under unstressed conditions, HSP27 was identified at a high level in astrocytes (> 99%), at a low level in neurons (7%), and at a minimally detectable level in microglia (< 1%), whereas it was undetectable in oligodendrocytes. Under these conditions, HSP27 was located in the cytoplasm, fractionated into the Triton X-100-soluble phase, and composed chiefly of the basic isoform (HSP27a). After exposure to heat stress (43 degrees C/90 min), the level of HSP27 expression was not altered in astrocytes but was elevated significantly in neurons (11-21%) and microglia (4-7%) during 8-48 hr postrecovery periods, while it remained undetectable in oligodendrocytes. In addition, various human neural cell lines exhibited differential patterns of HSP27 expression under unstressed and heat-stressed conditions. Following heat shock treatment (45 degrees C/30 min), granular aggregates of HSP27 were identified in the cytoplasm of astrocytes. Under heat-stressed conditions, HSP27 was distributed within the Triton X-100-insoluble fraction associated with an increase in two more acidic isoforms (HSP27b and HSP27c). HSP27 and alpha B-crystallin were coexpressed in astrocytes under unstressed and heat-stressed conditions. When astrocytes were exposed to known HSP27 inducers, hydrogen peroxide and cysteamine reduced the synthesis of HSP27, while estradiol showed no effects. The differential patterns of constitutive and heat-induced expression of HSP27 in cultured human neurons and glial cells suggest that the cellular mechanisms by which HSP27 expression is regulated are different among various cell types in the human central nervous system.

Variation in the expression and/or phosphorylation of the human low molecular weight stress protein during in vitro cell differentiation

Members of the low molecular weight heat shock protein (hsp) family show regulated expression in both Drosophila and mice during development and differentiation. Here we have examined whether similar regulation of the single low molecular weight hsp (hsp 28) of humans exhibits differences in either its expression and/or phosphorylation during the course of in vitro differentiation of hematopoietic cells. In the promyelocytic leukemic cell line, HL-60, we show that early after commitment of the cells to a macrophage-like phenotype (via exposure to phorbol ester myristate, PMA) there occurs an accompanying increased phosphorylation of hsp 28. Over time and as the cells become terminally differentiated the levels of hsp 28 increase significantly. In contrast, cells stimulated to adopt a granulocyte-like phenotype (e.g. exposed to either dimethyl sulfoxide or retinoic acid) show no changes in either the phosphorylation or expression of hsp 28. Moreover, once differentiated the granulocyte-like cells no longer appear capable of phosphorylating hsp 28. Human K562 cells, in response to hemin, rapidly increase their expression and phosphorylation of hsp 28 during the course of their differentiation into erythroid-like cells. Addition of PMA to the K562 cells induces differentiation into a megakaryocyte-like phenotype but is not accompanied by changes in hsp 28 phosphorylation/expression. In the case of the HL-60 cells, differentiation toward the macrophage like lineage is accompanied by an increased adherence of the cells to their substratum and an apparent association of hsp 28 with the actin cytoskeleton.

Hormonal regulation of HSP27 expression in human endometrial epithelial and stromal cells

HSP27 has been analysed immunohistochemically in epithelium and stroma of premenopausal endometria obtained at different stages of the menstrual cycle and in endometria from postmenopausal women receiving oestrogens either alone or in combination with a progestin. The data indicate that HSP27 is increased by oestrogen and inhibited by progestins in glandular epithelium but not stroma. Oestrogen does not increase HSP27 in stromal cells and HSP27 is only present in stromal decidual cells seen in the late secretory phase where it continues to be detectable until the tenth week of gestation. Hormonal regulation of HSP27 is clearly different in endometrial epithelium and stroma and additional regulatory factors may be important as oestrogen alone does not increase postmenopausal epithelial HSP27 to the levels seen in the proliferative phase of premenopausal samples.

A 27 kDa heat shock protein that has anomalous prognostic powers in early and advanced breast cancer

This paper describes a prospective immunohistochemical analysis of 27 kDa heat shock protein (HSP27) in 361 patients with primary breast cancer in relation to disease-free survival (DFS) and survival from first relapse (SR). Oestradiol (ER) and progesterone (PR) receptors were also quantitated and related to the HSP27 data. While ER positively predicted a good outcome for both DFS and SR, HSP27 positivity predicted a prolonged SR but short DFS. The association between HSP27 and DFS only attained statistical significance in node-negative patients. Subgroup analysis reinforced the complementary relationship of HSP27 and ER for SR and opposing influences for DFS. In both node-negative and node-positive women, ER+ HSP27- patients had a longer DFS than ER- HSP27+ counterparts. There was no relationship between HSP27 and overall survival. HSP27 staining was highly correlated with ER but not PR, patient age, tumour size or menstrual status. There was a marginal correlation (P = 0.04) with histological grade with well-differentiated tumours having the highest HSP27. Cox multivariate regression analysis of the contribution of HSP27 in the presence of data on ER, PR, stage, nodal status and histological grade indicated that HSP27 was not of independent prognostic importance for DFS or overall survival and was only of borderline significance for OS (P < 0.07). However, in the absence of ER and PR data, HSP27 staining is an effective way of getting the same prognostic information. HSP27 staining appears to correlate with different biological features in early and advanced breast, high HSP27 being linked with short DFS in node-negative patients but with prolonged survival from first recurrence.