Expression of heat shock protein 72 in renal cell carcinoma: possible role and prognostic implications in cancer patients

Ha-ras(val12) induces HSP70b transcription via the HSE/HSF1 system, but HSP70b expression is suppressed in Ha-ras(val12)-transformed cells

Heat shock proteins (Hsps) are overexpressed in many tumors, but are downregulated in some tumors. To check for a direct effect of Ha-Ras(val12) on HSP70 transcription, we transiently expressed the oncoprotein in Rat1 fibroblasts and monitored its effect on HSP70b promoter-driven reporter gene. We show that expression of Ha-Ras(val12) induced this promoter. Promoter analysis via systematic deletions and point mutations revealed that Ha-Ras(val12) induces HSP70b transcription via heat shock elements (HSEs). Also, Ha-Ras(val12) induction of HSE-mediated transcription was dramatically reduced in HSF1-/- cells. Yet, residual effect of Ha-Ras(val12) that was still measured in HSF1-/- cells suggests that some of the Ha-Ras(val12) effect is Hsf1-independent. When HSF1-/- cells, stably expressing Ha-Ras(val12), were grown on soft agar only small colonies were formed suggesting a role for heat shock factor 1 (Hsf1) in Ha-Ras(val12)-mediated transformation. Although Ha-ras(Val12) seems to be an inducer of HSP70's expression, we found that in Ha-ras(Val12-)transformed fibroblasts expression of this gene is suppressed. This suppression is correlated with higher sensitivity of Ha-ras(val12)-transformed cells to heat shock. We suggest that Ha-ras(Val12) is involved in Hsf1 activation, thereby inducing the cellular protective response. Cells that repress this response are perhaps those that acquire the capability to further proliferate and become transformed clones.

HSP90 and the chaperoning of cancer

Standing watch over the proteome, molecular chaperones are an ancient and evolutionarily conserved class of proteins that guide the normal folding, intracellular disposition and proteolytic turnover of many of the key regulators of cell growth, differentiation and survival. This essential guardian function is subverted during oncogenesis to allow malignant transformation and to facilitate rapid somatic evolution. Pharmacologically 'bribing' the essential guard duty of the chaperone HSP90 (heat-shock protein of 90 kDa) seems to offer a unique anticancer strategy of considerable promise.

Cancer immunotherapy and heat-shock proteins: promises and challenges

Recent mechanistic studies on the role of heat-shock proteins (HSPs) to induce innate and adaptive immune responses have resulted in conflicting reports. Whereas some groups reported that HSPs have direct immunological function, others emphasised the endotoxin contamination of HSP preparations and questioned the antigen-specificity of HSP vaccines. The present review will discuss these issues and suggest that HSPs have diverse and distinct immunological functions that could be superimposed on effects resulting from endotoxin contamination or misunderstood by using experimental procedures with inadequate controls. To understand the actual function of HSPs in their interaction with the immune system, methods and procedures need to be optimised and appropriate controls need to be used. These points should also clarify the conflicting findings about HSPs and promote our knowledge about other immuologically important components that may be present in HSP preparations.

Anti-tumour activity of heat-shock protein 60-recognizing CD4+ T cells against syngeneic murine renal cell carcinoma

OBJECTIVES

To determine whether heat-shock protein (HSP) 60-recognizing CD4(+) T cells show antitumour activity against renal carcinoma (RENCA) cells, as HSP is highly expressed by tumour cells and induced in cells by various stresses, including transformation.

MATERIALS AND METHODS

RENCA, a renal cortical adenocarcinoma cell line of BALB/c origin, was used. Expression of major histocompatibility complex (MHC) class I, class II and HSP-60 on RENCA tumour cells was analysed by flow cytometry. BASL1.1, an autoreactive T-helper type 1 type CD4(+) T cell clone established by us, and that recognises HSP-60, was also used for a tumour-neutralising assay.

RESULTS

The RENCA cells were negative for MHC class II, but expressed intracellular HSP-60. In the tumour-neutralising assay, BASL1.1 cells significantly suppressed the in vivo growth of RENCA cells. Three of five mice rejected RENCA cells when co-inoculated with BASL1.1 cells.

CONCLUSIONS

These results indicate that HSP-60-recognizing CD4(+) T cells have the potential to eliminate renal cell carcinoma in vivo and that the eliciting of an anti-self T cell response at the tumour site can lead to regression of renal cancer.

Expressional patterns of chaperones in ten human tumor cell lines

Background

Chaperones (CH) play an important role in tumor biology but no systematic work on expressional patterns has been reported so far. The aim of the study was therefore to present an analytical method for the concomitant determination of several CH in human tumor cell lines, to generate expressional patterns in the individual cell lines and to search for tumor and non-tumor cell line specific CH expression.

Human tumor cell lines of neuroblastoma, colorectal and adenocarcinoma of the ovary, osteosarcoma, rhabdomyosarcoma, malignant melanoma, lung, cervical and breast cancer, promyelocytic leukaemia were homogenised, proteins were separated on two-dimensional gel electrophoresis with in-gel digestion of proteins and MALDI-TOF/TOF analysis was carried out for the identification of CH.

Results

A series of CH was identified including the main CH groups as HSP90/HATPas_C, HSP70, Cpn60_TCP1, DnaJ, Thioredoxin, TPR, Pro_isomerase, HSP20, ERP29_C, KE2, Prefoldin, DUF704, BAG, GrpE and DcpS.

Conclusions

The ten individual tumor cell lines showed different expression patterns, which are important for the design of CH studies in tumor cell lines. The results can serve as a reference map and form the basis of a concomitant determination of CH by a protein chemical rather than an immunochemical method, independent of antibody availability or specificity.

Evolving immunotherapeutic strategies in bladder and renal cancer

For patients with urological cancers, immunotherapy is currently a treatment option for metastatic renal cell carcinoma, and those with "high risk" superficial bladder cancers. In this review, our current understanding of tumour immune escape is discussed. The principles and role of current immunotherapies for these tumours are described, and new areas of immunotherapeutic promise are highlighted.

Small molecule modulators of endogenous and co-chaperone-stimulated Hsp70 ATPase activity

The molecular chaperone and cytoprotective activities of the Hsp70 and Hsp40 chaperones represent therapeutic targets for human diseases such as cancer and those that arise from defects in protein folding; however, very few Hsp70 and no Hsp40 modulators have been described. Using an assay for ATP hydrolysis, we identified and screened small molecules with structural similarity to 15-deoxyspergualin and NSC 630668-R/1 for their effects on endogenous and Hsp40-stimulated Hsp70 ATPase activity. Several of these compounds modulated Hsp70 ATPase activity, consistent with the action of NSC 630668-R/1 observed previously (Fewell, S. W., Day, B. W., and Brodsky, J. L. (2001) J. Biol. Chem. 276, 910-914). In contrast, three compounds inhibited the ability of Hsp40 to stimulate Hsp70 ATPase activity but did not affect the endogenous activity of Hsp70. Two of these agents also compromised the Hsp70/Hsp40-mediated post-translational translocation of a secreted pre-protein in vitro. Together, these data indicate the potential for continued screening of small molecule Hsp70 effectors and that specific modulators of Hsp70-Hsp40 interaction can be obtained, potentially for future therapeutic use.

Significance of heat shock protein-27 expression in patients with renal cell carcinoma

OBJECTIVES

To investigate heat shock protein (HSP)-27 expression in patients with renal cell carcinoma (RCC) and examine its biologic significance. HSPs were first defined as proteins induced by heat shock and other environmental and pathophysiologic stresses. They are implicated in protein-protein interactions and are thought to play an important role in cancer. The expression of HSP-27 has been demonstrated in some human tumors.

METHODS

The expression of HSP-27 was studied in tumor and normal parenchyma tissue specimens from 76 patients with RCC by immunohistochemistry. The findings were correlated with clinical stage, lymph node metastasis, histologic grade, and survival.

RESULTS

Of the 76 RCC tissue specimens studied, the presence of HSP-27 was demonstrated in 73 (96%). The expression was low in 10 patients (14%), intermediate in 38 (50%), and high in 25 (33%). HSP-27 expression was greater in RCC tissue compared with adjacent noncancerous renal tissue (P <0.001). An inverse relationship was found between tumor stage and HSP-27 expression (r = -0.281, P = 0.016). However, no statistically significant difference was observed in progression-free survival with respect to HSP-27 expression. No relationship was found between HSP-27 expression and tumor grade, lymph node metastasis, distant metastasis, or cause-specific survival.

CONCLUSIONS

Our data suggest that HSP-27 expression is not a powerful and statistically significant prognostic indicator for disease-free survival for patients with RCC.

Altered Hsp90 function in cancer: A unique therapeutic opportunity

Molecular chaperones or so-called heat shock proteins serve as central integrators of protein homeostasis within cells. In performing this function, they guide the folding, intracellular disposition, and proteolytic turnover of many key regulators of cell growth, differentiation, and survival. Recent data show essential roles for the chaperones in facilitating malignant transformation at the molecular level and support the concept that their altered utilization during oncogenesis is critical to the development of human cancers. The field is evolving rapidly, but it has become apparent that chaperones can serve as biochemical buffers at the phenotypic level for the genetic instability that is characteristic of many human cancers. Chaperone proteins thus allow tumor cells to tolerate the mutation of multiple critical signaling molecules that would otherwise be lethal. Much of the recent progress in understanding the complex role of heat shock proteins in tumorigenesis has been made possible by the discovery of several natural product antitumor antibiotics that selectively inhibit the function of the chaperone Hsp90. These agents have been used as probes to define the biological functions of Hsp90 at the molecular level and to validate it as a novel target for anticancer drug action. One of these agents, 17-allylamino,17-demethoxygeldanamycin (NSC 330507) has begun phase II clinical trials, and several second-generation compounds are now in late preclinical development. The best way to use Hsp90 inhibitors as anticancer agents remains to be defined. Trials accomplished to date, however, serve as proof of principle that Hsp90 function can be modulated pharmacologically without undue toxicity in humans. Given the redundancy and complexity of the signaling pathway abnormalities present in most cancers, the ability of Hsp90 inhibitors to alter the activity of multiple aberrant signaling molecules instead of just one or two (as most current-generation molecular therapeutics have been designed to do) may prove of unique therapeutic benefit.

Heat shock protein 70 is induced in mouse human colon tumor xenografts after sublethal radiofrequency ablation

BACKGROUND

Radiofrequency ablation (RFA) destroys tumor cells by generating high temperatures through ionic vibration. Tumor recurrence may be a direct function of sublethal temperature. Further, a set of proteins called heat shock proteins (HSPs) can be synthesized under heat stress to facilitate recovery of tumor cells from heat damage.

METHODS

Subcutaneous xenografts were induced in nude mice by injection with HT29 human colon cancer cells. The tumors were exposed surgically and subjected to RFA. The tumors were randomly assigned to achieve a target tumor temperature of 42 degrees C, 45 degrees C, or 50 degrees C. Total RNA and cell lysates were isolated from tumor tissues and subjected to reverse transcription-polymerase chain reaction and Western blot analyses, respectively, at various time points after treatments for assessing HSP expression. For in vitro experiments, HT29 cells were subjected to variable temperatures, and HSP expression was assayed.

RESULTS

During a 50-day follow-up, the recurrence rates were 0% at 50 degrees C, 30% at 45 degrees C, and 100% at 42 degrees C. The messenger RNA and protein levels of HSP90 and HSP27 remained unchanged after RFA at 45 degrees C; however, HSP70 was induced at 4 and 10 hours after RFA. In vitro HT29 culture cells subjected to a heated water bath exhibited a cellular sensitivity to heat and change of HSP expression similar to those in tumor xenografts subjected to RFA.

CONCLUSIONS

Our data establish the requisite heat parameters during RFA for human colon tumors in vitro and in vivo. Because HSP70 plays an important role in protecting cell death from a variety of stresses, HSP70 could be a potential target for enhancing the efficacy of RFA.

Heat shock proteins in the genitourinary system

Heat shock proteins are ubiquitous molecules that are expressed in all living organisms in response to stress. They have two specific roles: protection against cell damage and modulation of the immune response. Recent studies have dramatically increased our knowledge and understanding of the role of heat shock proteins in the genitourinary system. This review uses a Medline approach to examine the current literature.

Heat shock proteins: their role in urological tumors

PURPOSE

Heat shock proteins are ubiquitous molecules that are expressed in response to stress in all living organisms. The 3 important roles in regard to cancer development that have also been described are the regulation of apoptosis, modulation of the immune response and drug resistance.

MATERIALS AND METHODS

Recent studies have dramatically increased our current knowledge and understanding of the role of heat shock protein in cancer. We used a MEDLINE approach to examine the past and current literature.

RESULTS

The roles of heat shock protein in relation to urological tumors, namely those of the prostate, bladder, kidney and testis, are diverse. There are possible sites for heat shock protein modifications that may lead to new therapeutic approaches to urological cancer.

CONCLUSIONS

The possibility of treating patients with vaccines earlier in the disease course may stimulate research.

Molecular chaperones in the kidney

The normal milieu of the kidney includes hypoxia, large osmotic fluxes, and an enormous amount of fluid/solute reabsorption. Renal adaptation to these conditions requires a host of molecular chaperones that stabilize protein conformation, target nascent proteins to their final intracellular destination, and prevent protein aggregation. Under physiologic or pharmacologic stress, inducible molecular chaperones provide additional mechanisms for repairing or degrading non-native proteins and for inhibiting stress-induced apoptosis. In contrast to intracellular chaperones, chaperones present on the cell surface regulate the immune system and have cytokine-like effects. A diverse range of chaperones and chaperone functions provide the renal cell with an armamentarium of responses to improve the chances of survival.

p53-dependent regulation of heat shock protein 72

BACKGROUND

p53 is a key regulator of the cellular stress response. p53 modulates the transcription of several genes.

OBJECTIVES

To examine the influence of p53 on expression of heat shock protein 72 (HSP72).

METHODS

Two model systems were used. (i) HSP72 expression was studied by Western blot on extracts from p53-proficient or p53-deficient primary mouse keratinocytes, and (ii) archival human anogenital skin from fibroepithelial polyps, human papillomavirus (HPV) 16/18-associated lesions or squamous cell carcinomas (SCCs) was subjected to immunostaining for HSP72.

RESULTS

Basal HSP72 expression was higher in keratinocytes from p53-deficient than from p53-proficient mice. Immunostaining for HSP72 was higher in HPV 16/18 lesions and SCCs, which have reduced p53 protein.

CONCLUSIONS

p53 status may influence the basal level of HSP72.

Heat shock protein expression and anti-heat shock protein reactivity in renal cell carcinoma

Heat shock proteins (HSP) are families of highly conserved proteins which are induced in cells and tissues upon exposure to extreme conditions causing acute or chronic stress. They exhibit distinct functions and have been implicated in the pathogenesis of a number of diseases, including cancer. A causal relationship between HSP expression and immunogenicity has been demonstrated in murine and human tumors and is also associated with the immune response. In order to investigate the correlation of HSP expression and their immunogenic potential in renal cell carcinoma (RCC), we here analyzed (i) the protein expression profile of various members of the HSP family in untreated and interferon (IFN)-gamma treated RCC cell lines as well as normal kidney epithelium, and (ii) the anti-heat shock protein reactivity in sera derived from RCC patients and healthy controls using proteomics-based techniques. A heterogeneous expression pattern of members of the HSP families was demonstrated in RCC cell lines and in cells representing normal renal epithelium. In some cases the expression rate is moderately altered by IFN-gamma treatment. In addition, a distinct anti-heat shock protein reactivity could be detected in autologous and allogeneic sera from RCC patients and healthy controls. These data suggest that HSP play a role in the immunogenicity of RCC and thus might be used for the design of immunization strategies to induce a potent antitumor response in this disease.

Significant correlation between expression of heat shock proteins 27, 70 and lymphocyte infiltration in esophageal squamous cell carcinoma

The objective of this study was to clarify the clinicopathologic and prognostic significance of heat shock proteins (HSP) 27 and 70 expression in esophageal squamous cell carcinoma (SCC). Immunohistochemical staining for HSPs 27 and 70 was performed on surgical specimens obtained from 62 patients with esophageal SCC. The expression of both HSPs 27 and 70 correlated inversely with depth of invasion (P<0.05) and pathologic stage (P<0.05), and correlated positively with lymphocyte infiltration (P<0.05). Reduction of HSP 70 expression was significantly correlated with poor prognosis (P<0.05). Patients with HSP 27-negative tumors tended to have a poor prognosis compared with patients with HSP 27-positive tumors. The present findings suggest that HSPs 27 and 70 are significant prognostic factors for esophageal SCC.

Heat shock proteins: endogenous modulators of apoptotic cell death

The highly conserved heat shock proteins (HSPs) accumulate in cells exposed to heat and a variety of other stressful stimuli. HSPs, which function mainly as molecular chaperones, allow cells to adapt to gradual changes in their environment and to survive in otherwise lethal conditions. The events of cell stress and cell death are linked and HSPs induced in response to stress appear to function at key regulatory points in the control of apoptosis. HSPs include antiapoptotic and proapoptotic proteins that interact with a variety of cellular proteins. Their expression level can determine the fate of the cell in response to a death stimulus, and apoptosis-inhibitory HSPs, in particular HSP27 and HSP70, may participate in carcinogenesis. This review summarizes apoptosis-regulatory function of HSPs.

Expression of heat shock proteins in osteosarcoma and its relationship to prognosis

The prognosis of osteosarcoma has been improved by chemotherapy. Heat shock proteins (HSPs) assist in folding proteins at posttranslation and degeneration under stress. We investigated the effect of HSPs on survival in osteosarcoma. Conventional osteosarcomas of the extremities from 70 patients aged 30 years or younger were used. Preoperational chemotherapy was performed in all cases. Tissues at surgery and biopsy were immunohistochemically stained with anti-HSP27, HSP47, HSP60, HSP70, HSP90alpha, HSP90beta, and p53 antibodies. We classified the cases in which more than 10% of tumor cells were positive into the overexpressing group. Overall survival was compared between the groups either overexpressing HSPs or not using Wilcoxon's test and Cox's proportional hazard model. The overexpression rate at biopsy was 22% (HSP27), 88% (HSP47), 66% (HSP60), 48% (HSP70(, 47% (HSP90alpha), 31% (HSP90beta), and 17% (p53), respectively. The rate at surgery was 33% (HSP27), 94% (HSP47), 60% (HSP60), 49% (HSP70), 28% (HSP90alpha), 40% (HSP90beta), and 17% (p53), respectively. HSP27 and p53 overexpression at biopsy had a negative prognostic value. HSP27 showed the strongest negative prognostic value in osteosarcoma. It is therefore important to investigate further its function in cellular regulation and drug resistance.

Intratumoral injection of dendritic cells derived in vitro in patients with metastatic cancer

BACKGROUND

Dendritic cells (DCs) are potent initiators of immune responses, and the infiltration of DCs into tumors may confer an improved prognosis. Whether the injection of DCs directly into tumors can mediate biologic activity was examined.

METHODS

Patients with metastatic dermal or subcutaneous tumors received granulocyte-macrophage-colony stimulating factor to increase the numbers of peripheral blood monocyte precursors. DCs were then generated from monocytes obtained by phlebotomy with granulocyte-macrophage-colony stimulating factor and interleukin-4 in autologous plasma. Tumors were injected at multiple sites with 30 million autologous DCs per tumor.

RESULTS

Seven patients with melanoma and three patients with breast carcinoma were treated. Injections were well tolerated. Regression of the injected tumors, beginning as early as 4 days after injection, was observed in four patients with melanoma and in two patients with breast carcinoma. Biopsies of regressing lesions showed lymphocyte infiltration associated with DCs and necrosis. Neutrophils and macrophages were not evident. Lymphocytes expanded from the regressing tumors proliferated in response to heat shock proteins, HSP70 and gp96, derived from autologous tumor. The DCs injected produced interferon-alpha and expressed Fas ligand mRNA but did not exhibit cytolytic activity in vitro. Expression of the costimulatory molecule, B7-2 (CD86), decreased on DCs after intratumoral injection.

CONCLUSIONS

This pilot study demonstrates that DCs derived in vitro can exist viably after intratumoral injection and can mediate biologic activity in situ. Tumor-derived heat shock proteins may be involved in the antitumor activity observed.

Heat shock proteins--modulators of apoptosis in tumour cells

Apoptosis is a genetically programmed, physiological method of cell destruction. A variety of genes are now recognised as positive or negative regulators of this process. Expression of inducible heat shock proteins (hsp) is known to correlate with increased resistance to apoptosis induced by a range of diverse cytotoxic agents and has been implicated in chemotherapeutic resistance of tumours and carcinogenesis. Intensive research on apoptosis over the past number of years has provided significant insights into the mechanisms and molecular events that occur during this process. The modulatory effects of hsps on apoptosis are well documented, however, the mechanisms of hsp-mediated protection against apoptosis remain to be fully defined, although several hypotheses have been proposed. Elucidation of these mechanisms should reveal novel targets for manipulating the sensitivity of leukaemic cells to therapy. This review aims to explain the currently understood process of apoptosis and the effects of hsps on this process. Several proposed mechanisms for hsp protection against apoptosis and the therapeutic implications of hsps in leukaemia are also discussed.

Heat shock proteins and cancer immunotherapy

Vaccination with heat shock proteins from tumor have been shown to elicit an anti-tumor response. Current studies indicate that the immunogenicity of HSPs is derived from the antigenic peptides which they associate with. Mechanisms by which the HSP-peptide complexes induce an immune response and the possible role of HSPs in antigen presentation is discussed in this article. The use of HSP-peptide complexes can be used as tumor vaccines for cancer immunotherapy is reviewed.

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.

Heat shock proteins as cellular lifeguards

Cells have developed complex ways to respond to various stresses. Interestingly, stresses such as heat, ischaemia and radiation can induce different cellular responses depending on their strength. While a mild stress induces a protective heat shock response, a more potent stress stimulus induces apoptosis and an even stronger one leads to necrosis. The heat shock or stress response, ie the synthesis of heat shock proteins (Hsps, stress proteins) in response to a mild stress, allows cells to adapt to gradual changes in their environment and to survive in otherwise lethal conditions. The ability of Hsps to protect cultured cells from both apoptosis and necrosis has been well demonstrated. Novel data suggest an important protective role for them also in vivo as they can protect heart and brain against ischaemia and lungs and liver against sepsis. Moreover, they can render tumours resistant to anticancer therapy. These and other cytoprotective effects of Hsps make them tempting targets for therapeutic interventions in several diseases.

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.

Escaping cell death: survival proteins in cancer

Defects in apoptosis signaling pathways are common in cancer cells. Such defects may play an important role in tumor initiation because apoptosis normally eliminates cells with damaged DNA or dysregulated cell cycle, i.e., cells with increased malignant potential. Moreover, impaired apoptosis may enhance tumor progression and promote metastasis by enabling tumor cells to survive the transit in the bloodstream and to grow in ectopic tissue sites lacking the otherwise required survival factors. Finally, raised apoptosis threshold may have deleterious consequences by rendering cancer cells resistant to various forms of therapy. The intensive apoptosis research during the past decade has resulted in the identification of several proteins which may promote tumorigenesis by inhibiting apoptosis. Of special relevance in human cancer are those commonly expressed in primary tumors and functioning at the common part of the signaling pathway leading to apoptosis. Proteins fulfilling these criteria include antiapoptotic members of the Bcl-2 protein family, heat shock proteins, Hsp70 and Hsp27, as well as survivin, the novel cancer-associated member of the inhibitor of apoptosis protein family. Understanding the molecular mechanisms of action of these proteins may offer novel modes of rationally and selectively manipulating the sensitivity of cancer cells to therapy.

Molecular chaperones in the etiology and therapy of cancer

Molecular chaperones are ubiquitous, well-conserved proteins that account for 2-5 % of all cellular proteins in most cells. The present review summarizes our current knowledge about their involvement in the etiology and therapy of cancer with special emphasis on the expression of chaperones in malignant cells, their role in folding of (proto)oncogene products, cell cycle regulation, cell differentiation and apoptosis, development of metastasis, and their participation in the recognition of malignant cells. We also overview the importance of chaperones in hyperthermia, drug resistance, and recent approaches in chaperone-immunotherapy.