Changes in the phosphorylation status of the 27 kDa heat shock protein (HSP27) associated with the modulation of growth and/or differentiation in MCF-7 cells

Weight loss-induced stress in subcutaneous adipose tissue is related to weight regain

Initial successful weight loss is often followed by weight regain after the dietary intervention. Compared with lean people, cellular stress in adipose tissue is increased in obese subjects. However, the relation between cellular stress and the risk for weight regain after weight loss is unclear. Therefore, we determined the expression levels of stress proteins during weight loss and weight maintenance in relation to weight regain. In vivo findings were compared with results from in vitro cultured human Simpson-Golabi-Behmel syndrome (SGBS) adipocytes. In total, eighteen healthy subjects underwent an 8-week diet programme with a 10-month follow-up. Participants were categorised as weight maintainers or weight regainers (WR) depending on their weight changes during the intervention. Abdominal subcutaneous adipose tissue biopsies were obtained before and after the diet and after the follow-up. In vitro differentiated SGBS adipocytes were starved for 96 h with low (0·55 mm) glucose. Levels of stress proteins were determined by Western blotting. WR showed increased expressions of β-actin, calnexin, heat shock protein (HSP) 27, HSP60 and HSP70. Changes of β-actin, HSP27 and HSP70 are linked to HSP60, a proposed key factor in weight regain after weight loss. SGBS adipocytes showed increased levels of β-actin and HSP60 after 96 h of glucose restriction. The increased level of cellular stress proteins in the adipose tissue of WR probably resides in the adipocytes as shown by in vitro experiments. Cellular stress accumulated in adipose tissue during weight loss may be a risk factor for weight regain.

Role of Pluronic block copolymers in modulation of heat shock protein 70 expression

PURPOSE

The goal of this study was to evaluate the relationship between previously demonstrated thermosensitising effects of the block copolymer, Pluronic, and heat shock protein 70 (Hsp70) expression in an experimental colorectal cancer model in vitro and in vivo.

MATERIALS AND METHODS

Rat colorectal carcinoma cells were treated with low-grade hyperthermia (43°C) alone or in combination with Pluronics L10 (3 mg/mL), L61 (0.3 mg/mL), or L64 (0.5 mg/mL) for 20 min. Adinosine triphosphate (ATP) levels and cell viability were determined using standard assays. Hsp70 expression was quantified by western blot for cells treated with L10, L61, and L64 at doses specified above and Pluronic P85 (10 mg/mL) alone and in combination with heat. BDIX rats with flank tumours were used to study the effect of L61 and hyperthermia on Hsp70 expression in vivo.

RESULTS

In vitro, treatment with L10, L61, and L64 plus low-grade hyperthermia lead to depletion of ATP levels to between 8 and 66% of untreated control after 24 h. Maximum expression of Hsp70 was observed at 9 h following hyperthermia alone. The combination of low-grade hyperthermia and Pluronic treatment reduced Hsp70 expression for up to 6 hours, and L10 appeared to completely inhibit the Hsp70 expression. In vivo, Hsp70 expression was increased 5 h after hyperthermia in BDIX rat tumour models and no Hsp70 expression was observed in L61 pre-treated and control groups.

CONCLUSION

Pluronic effectively improves hyperthermic and low-grade hyperthermic treatment in part due to reduction of Hsp70 expression.

Immunocompetent cells and cytokine expression in the rat periodontal ligament at the initial stage of orthodontic tooth movement

OBJECTIVE

The aim of the present study is to investigate the involvement of immunocompetent cells, pro-inflammatory cytokines and HSP, to evaluate a change of periodontal ligament during the initial stage of orthodontic tooth movement.

DESIGN

In the present study, we investigated the distributional density of immunocompetent cells, the localisation of cytokines, and the expression levels of their mRNA in the periodontal ligament during the initial stage of orthodontic tooth movement, using immunohistochemistry and real-time PCR.

RESULTS

Orthodontic tooth movement led to significant recruitment of OX6(+) cells and ED1(+) cells in the rat PDL. Double-immunofluorescence staining showed that some ED1(+) cells expressed pro-inflammatory factors of IL-1β and TNF-α in the PDL during orthodontic tooth movement. Real-time PCR analysis revealed that the expression levels of IL-1β (Il1b) and TNF-α (Tnf) mRNA gradually increased following its decrease after 1h of orthodontic tooth movement. These findings suggest that ED1(+) cells are involved in the expression of TNF-α and IL-1β and the subsequent regulation of bone resorption on pressure side. HSP27 (Hspb1) mRNA levels were significantly increased as compared with the control at 1h of the initial stage of treatment.

CONCLUSION

ED1(+) cells involved in the expression of TNF-α and IL-1β may play an important role in the initial reaction of the PDL and in the induction of the osteoclastic bone resorption during orthodontic tooth movement.

Phosphoproteome study reveals Hsp27 as a novel signaling molecule involved in GDNF-induced neurite outgrowth

Glial-cell-line-derived neurotrophic factor (GDNF) is a most potent survival factor for dopaminergic neurons. In addition, GDNF was also found to promote neurite outgrowth in dopaminergic neurons. However, despite the potential clinical and physiological importance of GDNF, its mechanism of action is unclear. Therefore, we employed a state-of-the-art proteomic technique, DIGE (Difference in two-dimensional gel electrophoresis), to quantitatively compare profiles of phosphoproteins of PC12-GFRalpha1-RET cells (that stably overexpress GDNF receptor alpha1 and RET) 0.5 and 10 h after GDNF challenge with control. A total of 92 differentially expressed proteins were successfully identified by mass spectrometry. Among them, the relative levels of phosphorylated Hsp27 increased significantly both in 0.5 and 10 h GDNF-treated PC12-GFRalpha1-RET cells. Confocal microscopy and Western blot results showed that the phosphorylation of Hsp27 after GDNF treatment was accompanied by its nuclear translocation. After the mRNA of Hsp27 was interfered, neurite outgrowth of PC12-GFRalpha1-RET cells induced by GDNF was significantly blocked. Furthermore, the percentage of neurite outgrowth induced by GDNF was also reduced by the expression of dominant-negative mutants of Hsp27, in which specific serine phosphorylation residues (Ser15, Ser78 and Ser82) were substituted with alanine. Our data also revealed that p38 MAPK and ERK are the upstream regulators of Hsp27 phosphorylation. Hence, in addition to the numerous novel proteins that are potentially important in GDNF mediated differentiation of dopaminergic cells revealed by our study, our data has indicated that Hsp27 is a novel signaling molecule involved in GDNF-induced neurite outgrowth of dopaminergic neurons.

HSP27 phosphorylation increases after 45°C or 41°C heat shocks but not after non-thermal TDMA or GSM exposures

PURPOSE

Experiments with cultured HeLa, S3 and E.A. Hy296 cells were performed to determine if exposure to acute (30 min at 45 degrees C) or chronic (2 h at 41 degrees C) heat shocks or to non-thermal exposures of radiofrequency radiation (RF) induce changes in HSP27 phosphorylation.

MATERIALS AND METHODS

The radiofrequency (RF) exposures used in this study were 847 MHz time division multiple access modulated (TDMA) at a specific absorption rate (SAR) of 5 W kg-1 for 1, 2 or 24 h or 900 MHz GSM modulated (GSM) at a SAR of 3.7 W kg-1 for 1, 2 or 5 h. HSP27 phosphorylation was evaluated by resolving the various phosphorylation forms using two-dimensional gel electrophoresis measuring the relative amount of each by densitometry. Alternatively, an antibody specific for phosphorylated HSP27 was used to detect changes in HSP27 phosphorylation levels. All heat shock and RF exposure conditions were analysed simultaneously along with a matched incubator control sample. Each experiment was repeated three times.

RESULTS

Following heat shock, the degree of phosphorylation of HSP27 varied with the heat dose, with acute hyperthermia (45 degrees C) having an increased proportion of higher phosphorylated forms. Exposure of HeLa S3 cells to 5 W kg-1 TDMA for 1, 2 or 24 h did not induce significant differences in the levels of HSP27 phosphorylation compared to incubator control or sham. Exposure of E.A. Hy926 cells to 3.7 W kg-1 900 MHz GSM for 1, 2 or 5 h did not induce significant differences in the levels of HSP27 phosphorylation compared to sham exposed.

CONCLUSIONS

Acute and moderate hyperthermia significantly increase HSP27 phosphorylation, but there was no significant change in the levels of HSP27 following non-thermal exposure to TDMA and GSM modulated RF radiations.

Chaperones in cell cycle regulation and mitogenic signal transduction: a review

Chaperones/heat shock proteins (HSPs) of the HSP90 and HSP70 families show elevated levels in proliferating mammalian cells and a cell cycle-dependent expression. They transiently associate with key molecules of the cell cycle control system such as Cdk4, Wee-1, pRb, p53, p27/Kip1 and are involved in the nuclear localization of regulatory proteins. They also associate with viral oncoproteins such as SV40 super T, large T and small t antigen, polyoma large and middle S antigen and EpsteinBarr virus nuclear antigen. This association is based on a J-domain in the viral proteins and may assist their targeting to the pRb/E2F complex. Small HSPs and their state of phosphorylation and oligomerization also seem to be involved in proliferation and differentiation. Chaperones/HSPs thus play important roles within cell cycle processes. Their exact functioning, however, is still a matter of discussion. HSP90 in particular, but also HSP70 and other chaperones associate with proteins of the mitogen-activated signal cascade, particularly with the Src kinase, with tyrosine receptor kinases, with Raf and the MAP-kinase activating kinase (MEK). This apparently serves the folding and translocation of these proteins, but possibly also the formation of large immobilized complexes of signal transducing molecules (scaffolding function).

Low-scale phosphoproteome analyses identify the mTOR effector p70 S6 kinase 1 as a specific biomarker of the dual-HER1/HER2 tyrosine kinase inhibitor lapatinib (Tykerb) in human breast carcinoma cells

BACKGROUND

Discovery of key proliferative and/or survival cascades closely linked to the biological effects of human epidermal growth factor receptor (HER) 1 (erbB-1) and/or HER2 (erbB-2) inhibitors may identify a priori mechanisms responsible for the development of acquired resistance in breast cancer disease. Here, we took advantage of a semiquantitative protein array technology to identify intracellular oncogenic kinases that distinctively correlate with breast cancer cell sensitivity/resistance to the dual-HER1/HER2 tyrosine kinase inhibitor lapatinib (Tykerb(R)).

MATERIALS AND METHODS

MCF-7 cells were forced to overexpress HER2 following stable transduction with pBABE-HER2 retroviruses. The Human Phospho-MAPK Array Proteome Profilertrade mark (R&D Systems) was used to molecularly assess the effects of both the mono-HER2 inhibitor trastuzumab (Herceptintrade mark) and the dual-HER1/HER2 inhibitor lapatinib on 21 different oncogenic kinases. A model of acquired resistance to lapatinib (MCF-7/HER2-Lap10 cells) was established by chronically exposing MCF-7/HER2 cells to increasing concentrations of lapatinib for >10 months.

RESULTS

Treatment of MCF-7/HER2 cells with either trastuzumab or lapatinib similarly impaired HER2-enhanced activation status (i.e. phosphorylation) of the mitogen-activated protein kinases, c-Jun N-terminal kinases 1-3 and p38alpha/beta/gamma/delta and of the serine/threonine kinases AKT, glycogen synthase kinase-3, p90 ribosomal s6 kinase1/2, and mitogen- and stress-activated protein kinase1/2. Trastuzumab was less effective than lapatinib at blocking extracellular-signal regulated kinase (ERK) 1/2 and, notably, it failed to deactivate the mammalian target of rapamycin (mTOR) effector p70S6K1. Conversely, lapatinib treatment caused a drastic decrease in the phosphorylation of p70S6K1 at ERK1/2-regulated sites (Thr(421)/Ser(424)) and, as a consequence, p70S6K1 activity measured by its phospho-Thr(389) levels was abolished. The mTOR inhibitor rapamycin was found to supraadditively increase lapatinib efficacy in MCF-7/HER2 cells [ approximately 10-fold enhancement; combination index (CI(50)) = 0.243 < 1.0 = additivity, P < 0.001] but not in p70S6K1 gene-amplified MCF-7 parental cells ( approximately 1.3-fold enhancement; CI(50) = 0.920 congruent with 1.0 = additivity). Lapatinib-resistant MCF-7/HER2-Lap10 cells, which are capable of growing in the continuous presence of 10 microM lapatinib without significant effects on cell viability, notably exhibited a lapatinib-insensitive hyperphosphorylation of p70S6K1. Rapamycin cotreatment suppressed p70S6K1 hyperactivation and synergistically resensitized MCF-7/HER2-Lap10 cells to lapatinib (>20-fold increase in lapatinib-induced cytotoxicity; CI(50) = 0.175 < 1.0 = additivity).

CONCLUSIONS

Serine-threonine kinase p70S6K1, a marker for mTOR activity that regulates protein translation, constitutes a specific biomarker for the biological effects of the dual-HER1/HER2 inhibitor lapatinib. The clinical implications of our data are that the efficacy of lapatinib might be enhanced with therapies that target the mTOR pathway. Rapamycin analogues such as CCI-779 (Temsirolimus) and RAD001 (Everolimus) may warrant further clinical evaluation to effectively delay or prevent the development of acquired resistance to lapatinib in HER2-positive breast cancer patients.

Overexpression of human Hsp27 inhibits serum-induced proliferation in airway smooth muscle myocytes and confers resistance to hydrogen peroxide cytotoxicity

Airway smooth muscle (ASM) hypertrophy and hyperplasia are characteristics of asthma that lead to thickening of the airway wall and obstruction of airflow. Very little is known about mechanisms underlying ASM remodeling, but in vascular smooth muscle, it is known that progression of atherosclerosis depends on the balance of myocyte proliferation and cell death. Small heat shock protein 27 (Hsp27) is antiapoptotic in nonmuscle cells, but its role in ASM cell survival is unknown. Our hypothesis was that phosphorylation of Hsp27 may regulate airway remodeling by modifying proliferation, cell survival, or both. To test this hypothesis, adenoviral vectors were used to overexpress human Hsp27 in ASM cells. Cells were infected with empty vector (Ad5) or wild-type Hsp27 (AdHsp27 WT), and proliferation and death were assessed. Overexpressing Hsp27 WT caused a 50% reduction in serum-induced proliferation and increased cell survival after exposure to 100 microM hydrogen peroxide (H(2)O(2)) compared with mock-infected controls. Overexpression studies utilizing an S15A, S78A, and S82A non-phosphorylation mutant (AdHsp27 3A) and an S15D, S78D, and S82D pseudo-phosphorylation mutant (AdHsp27 3D) showed phosphorylation of Hsp27 was necessary for regulation of ASM proliferation, but not survival. Hsp27 provided protection against H(2)O(2)-induced cytotoxicity by upregulating cellular glutathione levels and preventing necrotic cell death, but not apoptotic cell death. The results support the notion that ASM cells can be stimulated to undergo proliferation and death and that Hsp27 may regulate these processes, thereby contributing to airway remodeling in asthmatics.

HSP27 is a ubiquitin-binding protein involved in I-kappaBalpha proteasomal degradation

HSP27 is an ATP-independent chaperone that confers protection against apoptosis through various mechanisms, including a direct interaction with cytochrome c. Here we show that HSP27 overexpression in various cell types enhances the degradation of ubiquitinated proteins by the 26S proteasome in response to stressful stimuli, such as etoposide or tumor necrosis factor alpha (TNF-alpha). We demonstrate that HSP27 binds to polyubiquitin chains and to the 26S proteasome in vitro and in vivo. The ubiquitin-proteasome pathway is involved in the activation of transcription factor NF-kappaB by degrading its main inhibitor, I-kappaBalpha. HSP27 overexpression increases NF-kappaB nuclear relocalization, DNA binding, and transcriptional activity induced by etoposide, TNF-alpha, and interleukin 1beta. HSP27 does not affect I-kappaBalpha phosphorylation but enhances the degradation of phosphorylated I-kappaBalpha by the proteasome. The interaction of HSP27 with the 26S proteasome is required to activate the proteasome and the degradation of phosphorylated I-kappaBalpha. A protein complex that includes HSP27, phosphorylated I-kappaBalpha, and the 26S proteasome is formed. Based on these observations, we propose that HSP27, under stress conditions, favors the degradation of ubiquitinated proteins, such as phosphorylated I-kappaBalpha. This novel function of HSP27 would account for its antiapoptotic properties through the enhancement of NF-kappaB activity.

Proteomics reveals protein profile changes in doxorubicin--treated MCF-7 human breast cancer cells

MCF-7 cells are extensively used as a cell model to investigate human breast tumors and the cellular mechanism of antitumor drugs such as doxorubicin (DOX), an anthracycline antitumor drug widely used in clinical chemotherapy. To understand the effects of DOX on the protein expression, we perform a comprehensive proteomics to survey global changes in proteins after DOX treatment in MCF-7 cells. Exposure of MCF-7 cells to 0.1 microM DOX for 2 days induced a differentiation-like phenotype with prominent perinuclear autocatalytic vacuoles, abundant filamentous material, and irregular microvilli at the cell surface. In this study, we also present a proteome reference map of MCF-7 cells with 21 identified protein spots via analysis of N-terminal sequencing, mass spectrometry, immunoblot and/or computer matching with protein database. Based on the proteome map, we found that DOX causes a markedly decrease in the levels of three isoforms of heat shock protein 27 (HSP27) whereas the levels of other stress associated proteins including HSP60, calreticulin, and protein disulfide isomerase were not significantly altered in DOX-treated MCF-7 cells. Taken together, we suggest that that action of DOX on breast tumor cells may be partly related to dysregulation of HSP27 expression. Modulation of HSP27 levels may be a clinically useful potential target for design of antitumor drugs and controlling breast tumor growth.

Involvement of protein tyrosine phosphorylation and reduction of cellular sulfhydryl groups in cell death induced by 1' -acetoxychavicol acetate in Ehrlich ascites tumor cells

Elucidation of the mechanisms underlying potential anticancer drugs continues and unraveling these mechanisms would not only provide a conceptual framework for drug design but also promote use of natural products for chemotherapy. To further evaluate the efficacy of the anticancer activity of 1'-acetoxychavicol acetate (ACA), this study investigates the underlying mechanisms by which ACA induces death of Ehrlich ascites tumor cells. ACA treatment induced loss of cell viability, and Western blotting analysis revealed that the compound stimulated tyrosine phosphorylation of several proteins with 27 and 70 kDa proteins being regulated in both dose- and time-dependent manner prior to loss of viability. Protein tyrosine kinase inhibitor herbimycin A moderately protected cells from ACA-induced toxicity. In addition, cellular glutathione and protein sulfydryl groups were also significantly reduced both dose- and time-dependently during evidence of cell death. Replenishing thiol levels by antioxidant, N-acetylcysteine (NAC), an excellent supplier of glutathione and precursor of glutathione, substantially recovered the viability loss, but the recovery being time-dependent, as late addition of NAC (at least 30 min after ACA addition to cultures) was, however, ineffective. Addition of NAC to ACA treated cultures also abolished tyrosine phosphorylation of the 27 kDa protein. These results, at least partly, identify cellular sulfhydryl groups and protein tyrosine phosphorylation as targets of ACA cytotoxicity in tumor cells.

Identification and characterization of hic-5/ARA55 as an hsp27 binding protein

hsp27 has been reported to participate in a wide variety of activities, including resistance to thermal and metabolic stress, regulation of growth and differentiation, and acting as a molecular chaperone or a regulator of actin polymerization. We hypothesized that these diverse functions are regulated in a cell- or tissue-specific manner via interaction with various binding proteins. To investigate this hypothesis, we used hsp27 as a "bait" to screen a yeast two-hybrid cDNA library from rat kidney glomeruli and identified a novel hsp27 binding protein, hic-5 (also known as ARA55), a focal adhesion protein and steroid receptor co-activator. Biochemical interaction between hsp27 and hic-5 was confirmed by co-immunoprecipitation, and critical protein.protein interaction regions were mapped to the hic-5 LIM domains and the hsp27 C-terminal domain. Initial analysis of the functional role of hsp27.hic-5 interaction revealed that hic-5 significantly inhibited the protection against heat-induced cell death conferred by hsp27 overexpression in co-transfected 293T cells. In contrast, when a non-hsp27-interacting hic-5 truncation mutant (hic-5/DeltaLIM4) was co-expressed with hsp27, the hic-5 inhibition of hsp27 protection was absent. We conclude that hic-5 is a true hsp27 binding protein and inhibits the ability of hsp27 to provide protection against heat shock in an interaction-dependent manner.

Heat shock proteins in human cancer

The heat shock proteins (hsp) are ubiquitous molecules induced in cells exposed to sublethal heat shock, present in all living cells, and highly conserved during evolution. Their function is to protect cells from environmental stress damage by binding to partially denatured proteins, dissociating protein aggregates, to regulate the correct folding, and to cooperate in transporting newly synthesized polypeptides to the target organelles. The molecular chaperones are involved in numerous diseases, including cancer, revealing changes of expression. In this review, we mainly describe the relationship of hsp expression with human cancer, and discuss what is known about their post-translational modifications according to malignancies.

Differential expression of small heat shock protein 27 in the rat hippocampus and septum after fimbria-fornix lesion

mRNA, Western analysis and immunohistochemistry were used to study the expression of the small heat shock protein (HSP) 27 in the rat septum and hippocampus following fimbria-fornix lesions, a model of neurodegeneration and regeneration. (HSP) 27 mRNA level was increased 2.5-fold in the medial septum 3 days after lesion and this increase persisted for 10 days. In the hippocampus, after an initial 15-fold increase at 3 days post-injury, HSP27 mRNA returned to basal levels 10 days after the lesion. Three and 10 days after lesion, HSP27 protein levels were increased in the septum (4.5 and 5-fold, respectively) and hippocampus (65 and 10-fold, respectively). The morphology of the HSP27 positive cells was indistinguishable from that of GFAP-immunoreactive cells. In addition, in the septum of injured rats, occasional neurons were heavily labelled with anti-HSP27 antibodies. Thus, up-regulation of HSP27, particularly in glial cells, may be a component of glial input in the processes on degeneration/regeneration which occur in this model.

Janus kinase 2-dependent activation of p38 mitogen-activated protein kinase by growth hormone. Resultant transcriptional activation of ATF-2 and CHOP, cytoskeletal re-organization and mitogenesis

We demonstrate here that p38 mitogen-activated protein (MAP) kinase is activated in response to cellular stimulation by human GH (hGH) in Chinese hamster ovary cells stably transfected with GH receptor cDNA. This activation requires the proline-rich box 1 region of the GH receptor required for JAK2 association and is prevented by pretreatment of cells with the JAK2-specific inhibitor AG490. ATF-2 is both phosphorylated and transcriptionally activated by hGH, and its transcriptional activation also requires the proline-rich box 1 region of the GH receptor. Expression of wild type JAK2 can further enhance hGH-induced ATF-2-, CHOP-, and Elk-1-mediated transcriptional activation, whereas pretreatment with AG490 is inhibitory. Use of either specific pharmacological inhibitors or transient transfection of cells with p38alpha MAP kinase cDNA or a dominant negative variant demonstrated that hGH-stimulated transcriptional activation of ATF-2 and CHOP, but not Elk-1, is regulated by p38 MAP kinase. Both the p38 MAP kinase and p44/42 MAP kinase are critical for hGH-stimulated mitogenesis, whereas only p38 MAP kinase is required for hGH-induced actin cytoskeletal re-organization. p38 MAP kinase is therefore an important regulator in coordinating the pleiotropic effects of GH.

Anti-sense inhibition of small-heat-shock-protein (HSP27) expression in MCF-7 mammary-carcinoma cells induces their spontaneous acquisition of a secretory phenotype

This work was aimed at testing the hypothesis (hitherto supported only by indirect evidence) that, besides contributing to resistance to stress, the small heat-shock-protein HSP27 might be involved in the control of growth and differentiation in mammary-tumour cells, where it is known to be oestrogen-regulated. Therefore, MCF-7 cells were transfected with a modulatable human hsp27 anti-sense cDNA. Clones of transfectants (designated alphahsp27) were selected which, upon expression of the anti-sense, exhibited a decline in HSP27 accumulation, associated with a decrease in resistance to heat shock and in proliferation rate, the degree of the latter reflecting their respective reduction in HSP27 content. The effects of anti-sense inhibition of HSP27 production were similar to those exerted on parental cells by phorbol myristate (TPA). Both resulted in growth inhibition, accumulation of lipid droplets in the cytoplasm, formation of secretory microvesicles with internal microvilli and increased release of several proteins, including the isoforms of a 52-kDa protein, which we identified as the oestrogen-regulated protein cathepsin D, all this without noticeable change in actin organization. These data constitute the first direct support for the hypothesis that, at least in some cell types, HSP27 might play a modulatory role in cell differentiation and (perhaps by this) in proliferation. While allowing dissociation of this role from the known action of HSP27 on actin polymerization, they suggest similar modulation of the function of some protein(s) implicated in the acquisition of the secretory phenotype by MCF-7 cells, with HSP27 also exerting an inhibitory action that can be alleviated either by its phosphorylation (as occurs with TPA) or by inhibition of its production.

Prognostic significance of heat shock proteins 27 and 70 in patients with squamous cell carcinoma of the esophagus

BACKGROUND

Heat shock proteins (HSPs) first were defined as proteins induced by heat shock and other environmental and pathophysiologic stresses and are implicated in protein-protein interactions such as folding, translocation, and prevention of inappropriate protein aggregation. Many of their functions suggest that they play important roles in cancer.

METHODS

Immunohistochemical study for HSP 27 and HSP 70 was performed on buffered formalin fixed, paraffin embedded sections of 102 esophageal squamous cell carcinoma specimens using monoclonal anti-HSP 27 antibody and anti-HSP 70 antibody.

RESULTS

Normal squamous cells expressed both HSP 27 and HSP 70 with the exception of the basal layer. In cancerous tissue, expression of HSP 27 was evaluated as positive (+) (39 cases; 38%), reduced (+/-) (53 cases; 52%), or negative (-) (10 cases; 10%) and expression of HSP 70 was evaluated as (+) (14 cases; 14%), (+/-) (57 cases; 56%), or (-) (31 cases; 30%). There was a strong correlation between the expression of HSP 27 and HSP 70 (P < 0.0001). When compared with clinicopathologic features, expression of both HSP 27 and HSP 70 correlated negatively with lymph node metastases (P < 0.05), but not with depth of invasion or histologic grade. The reduction of the HSPs was associated significantly with poor postoperative survival (P < 0.0001). In addition, multivariate analysis revealed that HSP 27 (-) was the strongest prognostic factor among the clinicopathologic features.

CONCLUSIONS

This study suggests that the expression of HSP 27 and HSP 70 frequently is reduced in patients with esophageal squamous cell carcinoma and therefore should be considered an independent prognostic factor of this disease.

Prognostic significance of heat shock proteins 27 and 70 in patients with squamous cell carcinoma of the esophagus

BACKGROUND

Heat shock proteins (HSPs) first were defined as proteins induced by heat shock and other environmental and pathophysiologic stresses and are implicated in protein-protein interactions such as folding, translocation, and prevention of inappropriate protein aggregation. Many of their functions suggest that they play important roles in cancer.

METHODS

Immunohistochemical study for HSP 27 and HSP 70 was performed on buffered formalin fixed, paraffin embedded sections of 102 esophageal squamous cell carcinoma specimens using monoclonal anti-HSP 27 antibody and anti-HSP 70 antibody.

RESULTS

Normal squamous cells expressed both HSP 27 and HSP 70 with the exception of the basal layer. In cancerous tissue, expression of HSP 27 was evaluated as positive (+) (39 cases; 38%), reduced (+/-) (53 cases; 52%), or negative (-) (10 cases; 10%) and expression of HSP 70 was evaluated as (+) (14 cases; 14%), (+/-) (57 cases; 56%), or (-) (31 cases; 30%). There was a strong correlation between the expression of HSP 27 and HSP 70 (P < 0.0001). When compared with clinicopathologic features, expression of both HSP 27 and HSP 70 correlated negatively with lymph node metastases (P < 0.05), but not with depth of invasion or histologic grade. The reduction of the HSPs was associated significantly with poor postoperative survival (P < 0.0001). In addition, multivariate analysis revealed that HSP 27 (-) was the strongest prognostic factor among the clinicopathologic features.

CONCLUSIONS

This study suggests that the expression of HSP 27 and HSP 70 frequently is reduced in patients with esophageal squamous cell carcinoma and therefore should be considered an independent prognostic factor of this disease.