热休克蛋白 90--癌症治疗的新靶点

热休克蛋白90(heat shock protein90,Hsp90)作为分子伴侣参与调控、维持细胞内多种蛋白的构象和功能,以帮助细胞在应激环境刺激下正常生长。近年来研究表明很多癌基因蛋白均为Hsp90的作用靶点,因此抑制Hsp90的功能将促进这些癌基因蛋白的降解,有助于癌症治疗。体内外实验也证实了Hsp90抑制剂的抗肿瘤活性,其中17-烯丙胺-17-脱甲氧格尔德霉素(17-allylamio-17-desmethoxygeldanamycin,17-AAG)正在进行临床试验。     

Heat shock proteins gp96 as immunogens in cancer patients

Heat shock proteins have been the focus of many experimental studies during the last few years in order to understand their biology and their imunologic features. We conducted pre-clinical experiments showing that gp96 purified from human melanoma lines can represent melanoma antigens and stimulate T cells known to recognize such antigens. Clinical studies of vaccination were then initiated by our group by using heat-shock protein gp96 purified from autologous tumor tissues in patients with melanoma and colorectal carcinoma. The results of these trials in metastatic melanoma patients with measurable disease showed that a melanoma-specific T cell response can be generated or increased in approximately 50% of vaccinated patients. Moreover, signs of clinical responses were obtained consisting of two complete responses and three long-lasting stabilizations. Similar results were obtained in patients with liver metastases of colorectal cancer made disease-free by surgery. In both studies a clear association was found between T cell immune response induced by the vaccine and clinical response both in the trial of melanoma (tumor response) and in that of colorectal cancer patients (disease-free and overall survival at 5 years).     

Re-induction of hsp70 synthesis: An assay for thermotolerance

Of the many heat shock proteins (HSPs), hsp70 appears to correlate best with heat resistance, either permanent or transient. We have investigated various approaches to quantify the concentration of hsp70, and examined the relationship between hsp70 and cells' thermal sensitivity during the development and decay of thermotolerance in model systems. Here, experiments were performed to determine the possibility of using the rate of synthesis of hsp70 after a second test heat shock to predict the kinetics of thermotolerance. Specifically, we studied the relationship between the retained thermotolerance in a murine tumor cell line SQ-1 and a human tumor cell line, HCT-8, after fractionated heat doses and the cells' ability to re-initiate synthesis of hsp70 in response to an additional test heat dose in vitro. Monolayers of cells were exposed to a first heat treatment (e.g., 41°C, 4 h) and then incubated at 37°C for 0–72 h. At various times after the first heat treatment, cells were either challenged with a 45°C, 45 min heat shock to assess the residual thermotolerance by colony formation, or labelled with [³⁵S]methionine before or after an additional test heat dose (e.g. 43.5°C, 15 min). We found that the cells' ability to re-initiate hsp70 synthesis in response to the test heat shock inversely correlated with retained thermotolerance. Our data suggest the level of hsp70 in thermotolerant cells regulates the rate of synthesis of additional hsp70 in response to the subsequent heat challenge. Furthermore, the results showed that the rate of re-induction of hsp70 synthesis after a test shock can be used as a rapid measure of retained thermotolerance. This study suggests an approach for quantifying the level of retained thermotolerance during a course of fractionated hyperthermia.     

进展期胃癌HSP90的表达及其临床意义

目的 探讨热休克蛋白90（HSP90）在进展期胃癌组织中的表达情况,并分析其与胃癌侵袭、转移及预后的关系。方法 采用免疫组化染色法检测157例进展期胃癌组织中HSP90的表达情况,并分析HSP90表达与胃癌临床病理特征及预后的关系。结果 胃癌组织中HSP90高表达率为68.2％（107／157）。HSP90表达与肿瘤大小、肿瘤部位、浸润深度、淋巴结转移及临床分期有关（P＜0.05）,与MMP-9表达呈正相关（r=0.514,P＜0.001）。157例进展期胃癌患者的中位无复发生存时间（RFS）为27.0个月,中位总生存时间（OS）为33.0个月;HSP90低表达患者的中位RFS和OS均为60.5个月,而HSP90高表达者分别为15.0个月和20.0个月（P均＜0.001）。Cox多因素分析显示,HSP90表达为影响胃癌预后的独立因素（P＜0.05）。结论 HSP90表达与进展期胃癌的侵袭转移相关,其高表达提示预后不良。     

Argpyrimidine-modified Heat shock protein 27 in human non-small cell lung cancer: a possible mechanism for evasion of apoptosis

Tumors generally display a high glycolytic rate. One consequence of increased glycolysis is the non-enzymatic glycation of proteins leading to the formation of advanced glycation end-products (AGEs). Therefore, we studied the presence of AGEs in non-small cell lung cancer and consequences thereof. We show the presence of two AGEs, i.e. the major AGE N(epsilon)-(carboxymethyl)lysine (CML) and the methylglyoxal-arginine adduct argpyrimidine, in human non-small cell lung cancer tissues by immunohistochemistry. We found in squamous cell carcinoma and adenocarcinoma tissues a strong CML positivity in both tumour cells and tumour-surrounding stroma. In contrast, argpyrimidine positivity was predominantly found in tumor cells and was strong in squamous cell carcinomas, but only weak in adenocarcinomas (2.6+/-0.5 vs. 1.2+/-0.4, respectively; P<0.005). In accordance, argpyrimidine was found in the human lung squamous carcinoma cell line SW1573, while it was almost absent in the adenocarcinoma cell line H460. Heat shock protein 27 (Hsp27) was identified as a major argpyrimidine-modified protein. In agreement with a previously described anti-apoptotic activity of argpyrimidine-modified Hsp27, the percentage of active caspase-3 positive tumor cells in squamous cell carcinomas was significantly lower when compared to adenocarcinomas. In addition, incubation with cisplatin induced almost no caspase-3 activation in SW1573 cells while a strong activation was seen in H460 cells; which was significantly reduced by incubation with an inhibitor of glyoxalase I, the enzyme that catalyzes the conversion of methylglyoxal. These findings suggest that a high level of argpyrimidine-modified Hsp27 is a mechanism of cancer cells for evasion of apoptosis.     

Inhibition of HSP70: A challenging anti-cancer strategy

HSP70 is a chaperone that accumulates in the cells after many different stresses promoting cell survival in response to the adverse conditions. In contrast to normal cells, most cancer cells abundantly express HSP70 at the basal level to resist to various insults at different stages of tumorigenesis and during anti-cancer treatment. This cancer cells addiction for HSP70 is the rational for its targeting in cancer therapy. Much effort has been dedicated in the last years for the active search of HSP70 inhibitors. Additionally, the recent clinical trials on highly promising inhibitors of another stress protein, HSP90, showed compensatory increase in HSP70 levels and raised the question of necessity to combine HSP90 inhibitors with simultaneous inhibition of HSP70. Here we analyzed the recent advancement in creation of novel HSP70 inhibitors and different strategies for their use in anti-cancer therapy.     

A Phase II Open-Label Study of Ganetespib,a Novel Heat Shock Protein 90 Inhibitor for Patients With Metastatic Breast Cancer

BackgroundGanetespib is a small molecule, nongeldanamycin HSP90 inhibitor with potent inhibitory effects on HSP90-dependent oncoproteins of relevance to breast cancer pathogenesis. We therefore tested ganetespib in an unselected cohort of patients with MBC.Patients and MethodsPatients were treated with single agent ganetespib at 200 mg/m² once weekly for 3 weeks, on a 28-day cycle. Therapy was continued until disease progression. The primary end point was ORR using Reponse Evaluation Criteria in Solid Tumors version 1.1.ResultsTwenty-two patients were enrolled with a median age of 51(range, 38-70) years and a median Eastern Cooperative Oncology Group performance status of 0 (range, 0-1). Most patients had at least 2 previous lines of chemotherapy in the metastatic setting. Most common toxicities, largely grade 1/2, were diarrhea, fatigue, nausea, and hypersensitivity reaction. The ORR in this unselected population was 9%, with all responses coming from the subset of patients with HER2-positive MBC (2/13; 15%). One patient with TNBC had objective tumor regression in the lung metastases. The clinical benefit rate (complete response + partial response + stable disease > 6 months) was 9%, median progression-free survival was 7 weeks (95% confidence interval [CI], 7-19), and median overall survival was 46 weeks (95% CI, 27-not applicable).ConclusionThe study did not meet the prespecified criteria for ORR in the first stage of the Simon 2-stage model in this heavily pretreated unselected population of MBC. However, activity was observed in trastuzumab-refractory HER2-positive and TNBC. Ganetespib was well tolerated and responses in more targeted populations harboring specific HSP90-dependent oncoproteins justifies its further study, particularly as part of rational combinations.     

Nuclear Accumulation of p53 in Normal Human Fibroblasts Is Induced by Various Cellular Stresses which Evoke the Heat Shock Response, Independently of the Cell Cycle

Nuclear accumulation of p53 is induced by various DNA damaging agents (the p53 response). Induction of nuclear accumulation of p53 after various cellular stresses, mostly other than DNA damage, including heat shock, was examined in normal human fibroblasts by immunostaining and flow cytometry using a mouse anti-p53 monoclonal antibody. Immunostaining revealed nuclear accumulation of p53 within 6 h after various stresses [heat shock, osmotic shock, heavy metal (Cd), blockers of the cellular respiratory system (NaN₃), amino acid analogues (azetidine and canavanine), an inhibitor of protein synthesis (puromycin), and oxygen free radicals (H₂O₂)]. Heat shock proved to be one of the most effective inducers among these stresses. FACScan analysis revealed that this induction of p53 occurred regardless of the stage in the cell cycle and that accumulation of cells in G2/M occurred. As all of these stresses are known to induce the heat shock response, the mechanism of p53 induction after stresses and that of heat shock response may share, at least partly, some common signaling pathway(s).     

Cytosolic-nuclear Tumor Promoter-specific Binding Protein: Association with the 90 kDa Heat Shock Protein and Translocation into Nuclei by Treatment with 12-O-Tetradecanoylphorbol 13-Acetate

Suspension-cultured HeLa cells possess a cytosolic-nuclear tumor promoter-specific binding protein (CN-TPBP) which lacks protein kinase C activity. This CN-TPBP existed in cytosol of HeLa cells, but translocated into nuclear fraction of the cells after treatment of the cells with 12-O-tetradecanoyl-phorbol 13-acetate (TPA). The translation of CN-TPBP induced by TPA became apparent within 10 min after the treatment with TPA, and was completed within 3 h. CN-TPBP bound TPA with the association constant of 1.4X10¹⁰ M ⁻¹, and also bound teleocidin B, debromoaplysiatoxin, and thapsigargin in a mutually competitive manner. The binding affinity order of synthetic analogs of teleocidin B correlated with the adhesion-inducing potency order of the compounds toward human leukemia cell line HL-60. The apparent molecular weight of CN-TPBP under non-denaturing conditions was estimated to be 66–68 kDa. CN-TPBP forms a complex with the 90 kDa heat shock protein, and the complex was stabilized by the presence of molybdate. These characteristics of CN-TPBP are similar to those of the nuclear receptors of glucocorticoid and dioxin. These findings suggested that CN-TPBP acts as a nuclear receptor for tumor promoters, and that tumor promoters may exert their biological effects by binding to CN-TPBP.     

Heat shock proteins in prostate cancer: from tumorigenesis to the clinic

The heat shock proteins (HSP) constitute a superfamily of chaperone proteins present in all cells and in all cell compartments, operating in a complex interplay with synergistic/overlapping multiplicity of functions, even though the common effect is cell protection. Several reasons explain the need for investigating HSP in prostate cancer: (1) these molecules function as chaperones of tumorigenesis accompanying the emergence of prostate cancer cells, (2) they appear as useful molecular markers associated with disease aggressiveness and with resistance to anticancer therapies including hormone therapy, radiotherapy, chemotherapy and hyperthermia, and (3) they can be used as targets for therapies. The latter can be accomplished by: (i) interrupting the interaction of HSP (mainly HSPC1) with various client proteins that are protected from degradation when chaperoned by the HSP; (ii) using the chaperone and adjuvant capabilities of certain HSP to present antigenic peptides to the immune system, so this system can recognise the prostate tumour cells as foreign to mount an effective antitumoral response; and (iii) using treatment planning models taking into account the HSP expression levels to obtain more effective therapies. In summary, the study of the HSP during tumorigenesis as well as during cancer progression, and the inclusion of treatment designs targeting HSP combined with other treatment modalities, should improve prostate cancer survival in the near future.     

Heat shock protein-peptide complex-96 (Vitespen) for the treatment of cancer

Heat shock proteins (HSPs) are the most abundant and ubiquitous soluble intracellular proteins. Members of the HSP family bind peptides, they include antigenic peptides generated within cells. HSPs also interact with antigen-presenting cells (APCs) through CD91 and other receptors, eliciting a cascade of events that includes re-presentation of HSP-chaperoned peptides by major histocompatability complex (MHC), translocation of nuclear factor-kappaB (NFkB) into the nuclei, and maturation of dendritic cells (DCs). These consequences point to a key role of heat shock proteins in fundamental immunological phenomena such as activation of APCs, indirect presentation (or cross-priming) of antigenic peptides, and chaperoning of peptides during antigen presentation. The properties of HSPs also allow them to be used for immunotherapy of cancers and infections in novel ways. This paper reviews the development and clinical trial progress of vitespen, an HSP peptide complex vaccine based on tumor-derived glycoprotein 96.     

A smoking-based carcinogenesis model for lung cancer risk prediction

Lung cancer is the leading cancer killer for both men and women worldwide. Over 80% of lung cancers are attributed to smoking. In this analysis, the authors propose to use a two-stage clonal expansion (TSCE) model to predict an individual's lung cancer risk based on gender and smoking history. The TSCE model is traditionally fitted to prospective cohort data. Here, the authors describe a new method that allows for the reconstruction of cohort data from the combination of risk factor data obtained from a case-control study, and tabled incidence/mortality rate data, and discuss alternative approaches. The method is applied to fit a TSCE model based on smoking. The fitted model is validated against independent data from the control arm of a lung cancer chemoprevention trial, CARET, where it accurately predicted the number of lung cancer deaths observed.     

HSP90 inhibitors in the context of heat shock and the unfolded protein response: effects on a primary canine pulmonary adenocarcinoma cell line*

Background: Agents targeting HSP90 and GRP94 are seldom tested in stressed contexts such as heat shock (HS) or the unfolded protein response (UPR). Tumor stress often activates HSPs and the UPR as pro-survival mechanisms. This begs the question of stress effects on chemotherapeutic efficacy, particularly with drugs targeting chaperones such as HSP90 or GRP94. We tested the utility of several HSP90 inhibitors, including PU-H71 (targeting GRP94), on a primary canine lung cancer line under HS/UPR stress compared to control conditions.

Methods: We cultured canine bronchoalveolar adenocarcinoma cells that showed high endogenous HSP90 and GRP94 expression; these levels substantially increased upon HS or UPR induction. We treated cells with HSP90 inhibitors 17-DMAG, 17-AAG or PU-H71 under standard conditions, HS or UPR. Cell viability/survival was assayed. Antibody arrays measured intracellular signalling and apoptosis profiles.

Results: HS and UPR had varying effects on cells treated with different HSP90 inhibitors; in particular, HS and UPR promoted resistance to inhibitors in short-term assays, but combinations of UPR stress and PU-H571 showed potent cytotoxic activity in longer-term assays. Array data indicated altered signalling pathways, with apoptotic and pro-survival implications. UPR induction?+?dual targeting of HSP90 and GRP94 swayed the balance toward apoptosis.

Conclusion: Cellular stresses, endemic to tumors, or interventionally inducible, can deflect or enhance chemo-efficacy, particularly with chaperone-targeting drugs. Stress is likely not held accountable when testing new pharmacologics or assessing currently-used drugs. A better understanding of stress impacts on drug activities should be critical in improving therapeutic targeting and in discerning mechanisms of drug resistance.     

ROS production,intracellular HSP70 levels and their relationship in human neutrophils: effects of age

ROS production and intracellular HSP70 levels were measured in human neutrophils for three age groups: young (20-59 years), elders (60-89 years) and nonagenarians (90 years and older). Elders showed higher levels of spontaneous intracellular ROS content compared with young and nonagenarian groups, which had similar intracellular ROS levels. Zymosan-induced (non-spontaneous) extracellular ROS levels were also similar for young and nonagenarians but were lower in elders. However, spontaneous extracellular ROS production increased continuously with age. Correlation analysis revealed positive relationships between HSP70 levels and zymosan-stimulated ROS production in the elder group. This was consistent with a promoting role for HSP70 in ROS-associated neutrophils response to pathogens. No positive correlation between ROS production and intracellular HSP70 levels was found for groups of young people and nonagenarians. In contrast, significant negative correlations of some ROS and HSP70 characteriscics were found for neutrophils from young people and nonagenarians. The observed difference in ROS and HSP70 correlations in elders and nonagenarians might be associated with an increased risk of mortality in older individuals less than 90 years old.     

Work stress and the risk of cancer: A meta-analysis of observational studies

Epidemiological studies have explored the relationship between work stress and the risk of cancer, but it remains unclear on whether work stress could increase the risk of cancer, or by other factors such as smoking and physical activity. Our study aimed to investigate the association between work stress and the risk of cancer and in relation to major potential confounding and modifying factors. We systematically searched three electronic databases, hand-searched references and citations of retrieved articles, and consulted experts to identify studies on assessing the association between work stress and the risk of cancer. The relative risks (RRs) of cancer associated with work stress were estimated using a random-effects model, and stratified by exposure measurement, study design, gender, study location, cancer site, smoking, drinking, body mass index, and physical activity. A total of 281,290 participants were included in this analysis. The significant association between work stress and the risk of colorectal (RR = 1.36; 95%CI: 1.16–1.59), lung (RR = 1.24; 95%CI: 1.02–1.49), and esophagus (RR = 2.12; 95%CI: 1.30–3.47) cancers were found. A statistically significant effect of work stress on colorectal cancer risk was observed in North America (RR = 1.51, 95% CI: 1.23–1.86, but not significant in Europe (RR = 1.16, 95% CI: 0.90–1.48). By contrast, a significant association between work stress and esophagus cancer was found in Europe, but not in North America. In addition, we did not observe any association between work stress and the risk of prostate, breast, or ovarian cancers. Findings of our study show that work stress is an important risk factor for colorectal, lung, and esophagus cancers. General public should be aware of the increased risk of cancer in employers with work stress. More efforts should be focused on understanding and studying the potential mechanisms which would help to identify employees at higher risk of these cancers.     

HSP90 expression and early recurrence in gastroenteropancreatic neuroendocrine tumors: Potential for a novel therapeutic target

BackgroundHeat shock protein (HSP)-90 promotes tumor growth and is overexpressed in many malignancies. HSP90 expression profile and its potential as a therapeutic target in primary and metastatic neuroendocrine tumors (NETs) are not known.MethodsHSP90 cytoplasmic expression and Ki-67 index were re-reviewed and scored by a pathologist blinded to all other clinicopathologic variables for patients who underwent resection of primary and metastatic gastroenteropancreatic (GEP) neuroendocrine tumors at a single institution (2000–2013). Primary outcome was recurrence-free survival (RFS).ResultsOf 263 tumors reviewed, 73% (n = 191) were primary GEP NETs, and 12% (n = 31) were NET liver metastases. Of the primary GEP-NETs, mean age was 56 years, 42% were male; 53% (n = 103) were pancreatic and 23% (n = 44) were small bowel. HSP90 expression was high in 34% (n = 64) and low in 66% (n = 127). Compared to low expression, high HSP90 was associated with advanced T-stage (T3/T4) (47 vs 27%; p = 0.02). Among patients who underwent curative-intent resections for primary, non-metastatic NETs (n = 145), high HSP90 was independently associated with worse RFS (HR 5.09, 95% CI 1.65–15.74; p = 0.005), after accounting for positive margin, LN involvement, increased tumor size, site of primary tumor, and Ki-67. When assessing NET liver metastases, 13% (n = 4) had high HSP90 expression and 87% (n = 26) had low expression. Patients with liver metastases with high HSP90 tended to have worse 1- and 3-year progression-free survival (25%, 25%) compared to those with low HSP90 (69%, 49%; p = 0.059).ConclusionHSP90 exhibits differential expression in resected GEP-NETs and liver metastases. High cytoplasmic expression is associated with early disease recurrence, even after accounting for other adverse pathologic factors. HSP90 inhibition may be a potential therapeutic target for neuroendocrine tumors.