Heat shock protein hsp70 in patients with axillary lymph node-negative breast cancer: prognostic implications

Association between the HSPA1B ±1267A/G polymorphism and cancer risk: a meta-analysis of 14 case-control studies

BACKGROUND

Previous epidemiological studies have suggested a potential role of the HSPA1B±1267A/G polymorphism in risk of developing cancer. However, the results were inconsistent. Therefore, we performed this meta-analysis to summarize the possible association with cancer risk.

MATERIALS AND METHODS

We retrieved relevant articles from PubMed, EMBASE, ISI Web of Science, Chinese Biomedical Literature and Chinese National Knowledge Infrastructure. Studies were selected using specific criteria. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to assess those associations. All analyses were performed using STATA software.

RESULTS

Fourteen case-control studies, including 1, 834 cancer cases and 2, 028 controls were included in this meta-analysis. Overall, the results indicated that the G allele of HSPA1B gene ±1267A/G was significantly associated with an increased cancer risk in all genetic models (G vs A: OR=1.51, 95%CI 1.17-1.95, p=0.001; GG vs AA: OR=2.93, 95%CI 1.50-5.74, p=0.002; AG vs AA: OR=1.48, 95%CI 1.10-1.98, p=0.009; GG/AG vs AA: OR=1.69, 95%CI 1.22-2.33, p=0.001; GG vs

AG/AA

OR=2.31, 95%CI 1.24-4.32, p=0.009). In the subgroup analysis stratified by ethnicity, a significant association was identified in Caucasians (G vs A: OR=1.35, 95%CI 1.08-1.69, p=0.008; GG/AG vs AA: OR=1.36, 95%CI 1.09-1.70, p=0.007), but not in Asians. In the stratified analysis by cancer types, individuals with the G allele showed an increased risk of hepatocellular carcinoma compared with carriers of the A allele (OR=2.40, 95%CI 1.47-3.91, p< 0.001). Inversely, individuals with the GG genotype showed a decreased risk of gastric cancer compared with carriers of the AG/GG genotypes (GG vs

AG/AA

OR=0.39, 95%CI 0.20-0.70, p=0.007).

CONCLUSIONS

This meta-analysis suggests associations between the HSPA1B ±1267A/G polymorphism and risk of cancer. However, this association might be Caucasian-specific and the G allele of this polymorphism probably increases risk of hepatocellular carcinoma while decreasing risk of gastric cancer. Further well-designed studies based on larger sample sizes are needed to validate these findings.

Heat shock protein 27 promotes cell proliferation through activator protein-1 in lung cancer

Heat shock protein 27 (HSP27) is an important regulator involved in the development of lung cancer. However, limited evidence exists concerning the underlying molecular mechanisms of its action. The results of the present study revealed that HSP27 was highly expressed in the lung cancer tissues of mice. In an in vitro model, the overexpression of HSP27 promoted cell proliferation, while HSP27 knockdown inhibited cell proliferation. HSP27 promoted cell proliferation in vitro by directly upregulating the expression of HSP27 target genes, which required the activation of the activator protein-1 (AP-1) signaling pathway. This was evaluated by the phosphorylation status of an important pathway component, c-Jun in lung cancer tissue and cells. These results suggested that HSP27 has a promotional role in lung cancer, and therefore indicated a novel mechanism involving lung cancer cell proliferation, which may underlie poor responses to therapy. Therefore, HSP27 may be a suitable therapeutic target for the treatment of lung cancer.

The Polycomb group protein RING1B is overexpressed in ductal breast carcinoma and is required to sustain FAK steady state levels in breast cancer epithelial cells

In early stages of metastasis malignant cells must acquire phenotypic changes to enhance their migratory behavior and their ability to breach the matrix surrounding tumors and blood vessel walls. Epigenetic regulation of gene expression allows the acquisition of these features that, once tumoral cells have escape from the primary tumor, can be reverted. Here we report that the expression of the Polycomb epigenetic repressor Ring1B is enhanced in tumoral cells that invade the stroma in human ductal breast carcinoma and its expression is coincident with that of Fak in these tumors. Ring1B knockdown in breast cancer cell lines revealed that Ring1B is required to sustain Fak expression in basal conditions as well as in Tgfβ-treated cells. Functionally, endogenous Ring1B is required for cell migration and invasion in vitro and for in vivo invasion of the mammary fat pad by tumoral cells. Finally we identify p63 as a target of Ring1B to regulate Fak expression: Ring1B depletion results in enhanced p63 expression, which in turns represses Fak expression. Importantly, Fak downregulation upon Ring1B depletion is dependent on p63 expression. Our findings provide new insights in the biology of the breast carcinoma and open new avenues for breast cancer prognosis and therapy.

HSP90 inhibitor NVP-AUY922 enhances TRAIL-induced apoptosis by suppressing the JAK2-STAT3-Mcl-1 signal transduction pathway in colorectal cancer cells

TRAIL has been shown to induce apoptosis in cancer cells, but in some cases, certain cancer cells are resistant to this ligand. In this study, we explored the ability of representative HSP90 (heat shock protein 90) inhibitor NVP-AUY922 to overcome TRAIL resistance by increasing apoptosis in colorectal cancer (CRC) cells. The combination of TRAIL and NVP-AUY922 induced synergistic cytotoxicity and apoptosis, which was mediated through an increase in caspase activation. The treatment of NVP-AUY922 dephosphorylated JAK2 and STAT3 and decreased Mcl-1, which resulted in facilitating cytochrome c release. NVP-AUY922-mediated inhibition of JAK2/STAT3 signaling and down-regulation of their target gene, Mcl-1, occurred in a dose and time-dependent manner. Knock down of Mcl-1, STAT3 inhibitor or JAK2 inhibitor synergistically enhanced TRAIL-induced apoptosis. Taken together, our results suggest the involvement of the JAK2-STAT3-Mcl-1 signal transduction pathway in response to NVP-AUY922 treatment, which may play a key role in NVP-AUY922-mediated sensitization to TRAIL. By contrast, the effect of the combination treatments in non-transformed colon cells was minimal. We provide a clinical rationale that combining HSP90 inhibitor with TRAIL enhances therapeutic efficacy without increasing normal tissue toxicity in CRC patients.

Heat shock proteins at the crossroads between cancer and Alzheimer's disease

Heat shock proteins 70 and heat shock proteins 90 (Hsp70/90) have been implicated in many crucial steps of carcinogenesis: stabilizing oncogenic proteins, inhibiting programmed cell death and replicative senescence, induction of tumor angiogenesis, and activation of the invasion and metastasis. Plenty of cancer related proteins have the ability of regulating the expression of Hsp70/90 through heat shock factor 1. Cancer and Alzheimer's disease (AD) have plenty of overlapping regions in molecular genetics and cell biology associated with Hsp70/90. The Hsp70, as a protein stabilizer, has a cellular protection against neurodegeneration of the central nervous system, while Hsp90 promote neurodegenerative disorders indirectly through regulating the expression of Hsp70 and other chaperones. All these make existing anticancer drugs target Hsp70/90 which might be used in AD therapy.

Investigation into the potential for hypoxic interior of neoplasms to enhance HSPA expression in glioma

Production of heat shock protein 70 (HSP70/HSPA) is induced by a wide range of cellular stress conditions, such as cancer and hypoxia. This study investigated the level of HSPA gene expression in human cell lines exposed to hypoxic conditions. Three human glioma cell lines were selected for this study, each representing different types of glioma (astrocytoma, oligodendroglioma and glioblastoma), with a normal human astrocyte cell line used as a control. HSPA RNA transcripts and proteins were examined in these samples using qRT-PCR, immunofluorescence and flow cytometry techniques. The average HSPA mRNA copy numbers detected in three glioma cell lines were approximately sixfold higher than in a normal astrocyte cell line. The expression of HSPA was induced in normal cell lines immediately after exposure to hypoxia with 33% of cells exhibiting expression. However, the effects of hypoxia on gene expression were marginal in glioma cells, due to the already increased levels of HSPA with both pre- and post-hypoxia samples showing expression in approximately 90% of cells. These results show that whilst the stress caused by both cancer and hypoxia induce HSPA expression the underlying imprint of tumourgenesis leads to sustained expression.

Reliability of HSP70 (HSPA) expression as a prognostic marker in glioma

Production of heat shock protein 70 (HSP70/HSPA) is induced by a wide range of cellular stress conditions, such as cancer and hypoxia, with production also being linked to tumourigenesis. HSPA mRNA transcripts and proteins were examined in three human glioma cell lines, representing astrocytoma, oligodendroglioma and glioblastoma, plus 18 clinical brain tissue samples. GAPDH was used as a control gene throughout these studies and exhibited a consistent level of expression in a normal astrocyte cell line, tumourous cell lines and tissue samples. In contrast, the average HSPA mRNA copy numbers detected in glioblastoma tissue were between 1.8- and 8.8-fold higher than in lower grade glioma and control tissue, respectively, which is suggestive of a grade-related transcription profile. Similar patterns of grade-related expression were also observed in glioma cell lines. This study indicates for the first time that HSPA expression in glioma cells may possibly be grade related, and hence could have potential as a prognostic marker.

Mapping photothermally induced gene expression in living cells and tissues by nanorod-locked nucleic acid complexes

The photothermal effect of plasmonic nanostructures has numerous applications, such as cancer therapy, photonic gene circuit, large cargo delivery, and nanostructure-enhanced laser tweezers. The photothermal operation can also induce unwanted physical and biochemical effects, which potentially alter the cell behaviors. However, there is a lack of techniques for characterizing the dynamic cell responses near the site of photothermal operation with high spatiotemporal resolution. In this work, we show that the incorporation of locked nucleic acid probes with gold nanorods allows photothermal manipulation and real-time monitoring of gene expression near the area of irradiation in living cells and animal tissues. The multimodal gold nanorod serves as an endocytic delivery reagent to transport the probes into the cells, a fluorescence quencher and a binding competitor to detect intracellular mRNA, and a plasmonic photothermal transducer to induce cell ablation. We demonstrate the ability of the gold nanorod-locked nucleic acid complex for detecting the spatiotemporal gene expression in viable cells and tissues and inducing photothermal ablation of single cells. Using the gold nanorod-locked nucleic acid complex, we systematically characterize the dynamic cellular heat shock responses near the site of photothermal operation. The gold nanorod-locked nucleic acid complex enables mapping of intracellular gene expressions and analyzes the photothermal effects of nanostructures toward various biomedical applications.

Geldanamycin attenuates 3‑nitropropionic acid‑induced apoptosis and JNK activation through the expression of HSP 70 in striatal cells

Although selective striatal cell death is a characteristic hallmark in the pathogenesis of Huntington's disease (HD), the underlying mechanism of striatal susceptibility remains to be clarified. Heat shock proteins (HSPs) have been reported to suppress the aggregate formation of mutant huntingtin and concurrent striatal cell death. In a previous study, we observed that heat shock transcription factor 1 (HSF1), a major transcription factor of HSPs, significantly attenuated 3‑nitropropionic acid (3NP)‑induced reactive oxygen species (ROS) production and apoptosis through the expression of HSP 70 in striatal cells. To investigate the differential roles of HSPs in 3NP‑induced striatal cell death, the effect of geldanamycin (GA), an HSP 90 inhibitor, was examined in 3NP‑stimulated striatal cells. GA significantly attenuated 3NP‑induced striatal apoptosis and ROS production with an increased expression of HSP 70. Triptolide (TL), an HSP 70 inhibitor, abolished GA‑mediated protective effects in 3NP‑stimulated striatal cells. To understand the underlying mechanism by which GA‑mediated HSP 70 protects striatal cells against 3NP stimulation, the involvement of various signaling pathways was examined. GA significantly attenuated 3NP‑induced c‑Jun N‑terminal kinase (JNK) phosphorylation and subsequent c‑Jun phosphorylation in striatal cells. Taken together, the present study demonstrated that GA exhibits protective properties against 3NP‑induced apoptosis and JNK activation via the induction of HSP 70 in striatal cells, suggesting that expression of HSP 70 may be a valuable therapeutic target in the treatment of HD.

Ibuprofen enhances the anticancer activity of cisplatin in lung cancer cells by inhibiting the heat shock protein 70

Hsp70 is often overexpressed in cancer cells, and the selective cellular survival advantage that it confers may contribute to the process of tumour formation. Thus, the pharmacological manipulation of Hsp70 levels in cancer cells may be an effective means of preventing the progression of tumours. We found that the downregulation of Hsp70 by ibuprofen in vitro enhances the antitumoural activity of cisplatin in lung cancer. Ibuprofen prominently suppressed the expression of Hsp70 in A549 cells derived from lung adenocarcinoma and sensitized them to cisplatin in association with an increase in the mitochondrial apoptotic cascade, whereas ibuprofen alone did not induce cell death. The cisplatin-dependent events occurring up- and downstream of mitochondrial disruption were accelerated by treatment with ibuprofen. The increase in cisplatin-induced apoptosis caused by the depletion of Hsp70 by RNA interference is evidence that the increased apoptosis by ibuprofen is mediated by its effect on Hsp70. Our observations indicate that the suppression of Hsp70 by ibuprofen mediates the sensitivity to cisplatin by enhancing apoptosis at several stages of the mitochondrial cascade. Ibuprofen, therefore, is a potential therapeutic agent that might allow lowering the doses of cisplatin and limiting the many challenge associated with its toxicity and development of drug resistance.

The complex function of hsp70 in metastatic cancer

Elevated expression of the inducible heat shock protein 70 (Hsp70) is known to correlate with poor prognosis in many cancers. Hsp70 confers survival advantage as well as resistance to chemotherapeutic agents, and promotes tumor cell invasion. At the same time, tumor-derived extracellular Hsp70 has been recognized as a "chaperokine", activating antitumor immunity. In this review we discuss localization dependent functions of Hsp70 in the context of invasive cancer. Understanding the molecular principles of metastasis formation steps, as well as interactions of the tumor cells with the microenvironment and the immune system is essential for fighting metastatic cancer. Although Hsp70 has been implicated in different steps of the metastatic process, the exact mechanisms of its action remain to be explored. Known and potential functions of Hsp70 in controlling or modulating of invasion and metastasis are discussed.

Expression of ST13 and HSP70 in gastric polyps and gastric cancer

AIM: To detect the expression of suppression of tumorigenicity13 (ST13) and heat shock protein70 (HSP70) in gastric polyps and gastric cancer and to analyze their correlation.

METHODS: Immunohistochemistry was used to detect the expression of ST13 and HSP70 in 30 cases of normal gastric mucosa, 30 cases of gastric polyps, 16 cases of gastric adenomatous polyps, and 30 cases of gastric carcinoma. The correlation between expression of ST13 and HSP70 in gastric polyps and gastric carcinoma was analyzed.

RESULTS: The rank mean for HSP70 expression in normal gastric mucosa, hyperplastic polyps, adenomatous polyps, gastric carcinoma was 32.35, 40.47, 63.25, and 82.48, respectively, showing a gradually decreasing trend (P < 0.01). The rank mean for expression of STl3 in normal gastric mucosa, hyperplastic polyps, adenomatous polyps, and gastric carcinoma group was 68.25, 59.77, 44.91 and 37.07, respectively, showing a gradually increasing trend. HSP70 and ST13 expression was negatively correlated in both adenomatous polyps and gastric cancer.

CONCLUSION: HSP70 protein expression shows an increasing trend and ST13 protein expression shows a decreasing trend in gastric carcinogenesis, suggesting that HSP70 and ST13 are closely related to the formation of gastric cancer. There is a negative correlation between HSP70 protein and ST13 protein expression in gastric adenomatous polyps and gastric carcinoma, suggesting that they may interact with each other.

Expression of heat shock protein 70 modulates the chemoresponsiveness of pancreatic cancer

Background/Aims

Heat shock protein (HSP) 70 is constitutively overexpressed in pancreatic cancer cells (PCCs) and appears to confer protection against chemotherapeutics. We investigated whether modulating HSP 70 increases chemoresponsiveness to gemcitabine in PCCs.

Methods

Varying concentrations of quercetin and gemcitabine, either alone or in combination, were added to PCCs (Panc-1 and MiaPaCa-2). MTT assay was performed to analyze cell viability. HSP 70 expression was assessed by Western blot analysis. Apoptosis was determined by measuring caspase-3 activity. Western blot for the LC3-II protein detected the presence of autophagy.

Results

HSP 70 levels were not affected by the incubation of Panc-1 and MiaPaCa-2 cells with gemcitabine, whereas with quercetin, the levels were reduced in both cell lines. The viability of both Panc-1 and MiaPaCa-2 cells significantly decreased with gemcitabine treatment but not with quercetin. A combination of gemcitabine and quercetin decreased the viability of both cell lines in a dose-dependent manner, which was more pronounced than gemcitabine treatment alone. Treatment with either gemcitabine or quercetin augmented caspase-3 activity in both cell lines, and a combination of these compounds further potentiated caspase-3 activity. LC3-II protein expression was negligible with gemcitabine treatment but marked with quercetin. The addition of gemcitabine to quercetin did not potentiate LC3-II protein expression.

Conclusions

Modulation of HSP 70 expression with quercetin enhanced the chemoresponsiveness of PCCs to gemcitabine. The mechanism of cell death was both apoptosis and autophagy.

ST13, a proliferation regulator, inhibits growth and migration of colorectal cancer cell lines

BACKGROUND AND OBJECTIVE

ST13, is the gene encoding the HSP70 interacting protein (HIP). Previous research has shown that ST13 mRNA and protein levels are down-regulated in colorectal cancer (CRC) tissues compared with adjacent normal tissues. This study aims at the role of ST13 in the proliferation and migration of CRC cells.

METHODS

The transcript level of ST13 in different CRC cell lines was evaluated by quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR). ST13-overexpressed and ST13-knockdown CRC cells were constructed respectively by lentiviral transduction, followed by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) assay, plate colony formation, cell-cycle analysis, and migration assays to evaluate the influence of ST13 on proliferation and migration in vitro. Moreover, a mouse xenograft study was performed to test in vivo tumorigenicity of ST13-knockdown CRC cells.

RESULTS

Lentivirus-mediated overexpression of ST13 in CRC cells inhibited cell proliferation, colony formation, and cell migration in vitro. In contrast, down-regulation of ST13 by lentiviral-based short hairpin RNA (shRNA) interference in CRC cells significantly increased cell proliferation and cloning efficiency in vitro. In addition, down-regulation of ST13 expression significantly increased the tumorigenicity of CRC cells in vivo.

CONCLUSIONS

ST13 gene is a proliferation regulator that inhibits tumor growth in CRC and may affect cell migration.

Prognostic significance of heat shock protein 70 expression in early gastric carcinoma

Background

Overexpression of heat shock protein 70 (HSP70) has been observed in many types of cancer including gastric adenocarcinomas, although the exact role of HSP70 in carcinogenesis remains unclear.

Methods

The study analyzed a total of 458 radical gastrectomy specimens which were immunohistochemically stained with HSP70, p53, and Ki-67 antibodies.

Results

The study determined that the expression of HSP70 was significantly increased in early gastric cancer (EGC) compared to advanced gastric cancer (p<0.001). The HSP70 expression was correlated with well-differentiated tumor type, intestinal type of Lauren classification and the lower pT and pN stage. Negative expression of Ki-67 and p53 expression was associated with poor prognosis. The study did not find any correlation between HSP70 and p53 expression. The study determined that HSP70 expression in the EGC subgroup was associated with a poor prognosis (p=0.009), as well as negative Ki-67 expression (p=0.006), but was not associated with p53. Based on multivariate analysis, HSP70 expression (p=0.024), negative expression of Ki-67, invasion depth and lymph node metastasis were determined to be independent prognostic markers.

Conclusions

HSP70 is expressed in the early stages of gastric adenocarcinoma. In EGC, HSP70 is a poor independent prognostic marker and is correlated with a low proliferation index.

The significance of heat shock proteins in breast cancer therapy

The evalutionary conserved heat shock proteins are involved basically life protecting mechanisms against harmful extracellular effects such as primarily heat shock response. Normally, the expression of these proteins is increased for cellular adaptation to high temperature. This increase is also important in the etiology of breast cancer. Overexpression of heat shock proteins is associated with reduced disease-free survival in breast cancer. However, increased expression of these proteins is related to acquired resistance of traditional chemotherapeutic drugs in use in breast cancer treatment. In this review, we discuss the multiple roles of heatshock proteins in resistance and where we are to overcome this in clinical practice.

The HSP70 family and cancer

The HSP70 family of heat shock proteins consists of molecular chaperones of approximately 70kDa in size that serve critical roles in protein homeostasis. These adenosine triphosphatases unfold misfolded or denatured proteins and can keep these proteins in an unfolded, folding-competent state. They also protect nascently translating proteins, promote the cellular or organellar transport of proteins, reduce proteotoxic protein aggregates and serve general housekeeping roles in maintaining protein homeostasis. The HSP70 family is the most conserved in evolution, and all eukaryotes contain multiple members. Some members of this family serve specific organellar- or tissue-specific functions; however, in many cases, these members can function redundantly. Overall, the HSP70 family of proteins can be thought of as a potent buffering system for cellular stress, either from extrinsic (physiological, viral and environmental) or intrinsic (replicative or oncogenic) stimuli. As such, this family serves a critical survival function in the cell. Not surprisingly, cancer cells rely heavily on this buffering system for survival. The overwhelming majority of human tumors overexpress HSP70 family members, and expression of these proteins is typically a marker for poor prognosis. With the proof of principle that inhibitors of the HSP90 chaperone have emerged as important anticancer agents, intense focus has now been placed on the potential for HSP70 inhibitors to assume a role as a significant chemotherapeutic avenue. In this review, the history, regulation, mechanism of action and role in cancer of the HSP70 family are reviewed. Additionally, the promise of pharmacologically targeting this protein for cancer therapy is addressed.

Hsps are up-regulated in melanoma tissue and correlate with patient clinical parameters

Heat shock proteins (hsps) have been studied in numerous cancer types, but a clear view of their clinical relevance in melanoma remains elusive. Therefore, the aim of this study was to investigate the expression of hsps in melanoma with respect to patient clinical parameters. Using Western immunoblotting, hsps 90, 70, 60, 40 and 32 were observed to be widely expressed in metastatic melanomas (n = 31), while immunofluorescence demonstrated that in the majority of samples these hsps, apart from hsp32, were increased in expression in melanoma cells compared with surrounding non-melanoma cells in situ (n = 8). Correlating hsp expression with patient clinical parameters indicated that greater hsp90 (P < 0.02) and hsp40 (P < 0.03) expression correlated with advanced stage (stage III Vs stage IV), while in the case of hsp40, this was additionally associated with reduced patient survival (P < 0.05). In contrast, higher hsp32 expression was associated with improved patient survival (P < 0.007). On the other hand, the expression of the other hsps did not correlate with any obtainable patient clinical parameters. This study provides further evidence for the importance of hsps in melanoma and for their use as therapeutic targets and biomarkers, but larger-scale follow-up studies are required to confirm these results.

Heat shock transcription factor-1 suppresses apoptotic cell death and ROS generation in 3-nitropropionic acid-stimulated striatal cells

Striatal neuronal cell death is one of the pathological features of Huntington's disease (HD). Overexpression of some heat shock proteins (HSPs) has been reported to suppress the aggregate formation of mutant huntingtin and concurrent cell death. Heat shock transcription factor-1 (HSF 1), a major transcription factor of HSPs, has also been reported to be increased in HD models. However, the exact role of HSF 1 in the pathogenesis of HD has not been clearly elucidated. 3-Nitropropionic acid (3NP), an irreversible inhibitor of the mitochondrial complex II, induces selective damage to the striatum in animals and produces clinical features of HD. To investigate roles of HSF 1 on 3NP-induced oxidative stress, HSF 1 was transiently overexpressed in striatal cells. Expression of HSF 1 significantly attenuated 3NP-induced apoptotic striatal cell death and resulted in increased expression of HSP 70. Furthermore, expression of HSF 1 significantly attenuated 3NP-induced intracellular reactive oxygen species (ROS) generation. Taken together, the present study clearly demonstrates that HSF 1 attenuates 3NP-induced apoptotic striatal cell death and ROS generation, possibly through HSP70 expression, suggesting that HSF 1 might be a valuable therapeutic target in the treatment of HD.

Spatial and temporal measurements of temperature and cell viability in response to nanoparticle-mediated photothermal therapy

Aim: Nanoparticle-enhanced photothermal therapy is a promising alternative to tumor resection. However, quantitative measurements of cellular response to these treatments are limited. This article introduces a Bimodal Enhanced Analysis of Spatiotemporal Temperature (BEAST) algorithm to rapidly determine the viability of cancer cells in vitro following photothermal therapy alone or in combination with nanoparticles. Materials & methods: To illustrate the capability of the BEAST viability algorithm, single wall carbon nanohorns were added to renal cancer (RENCA) cells in vitro and time-dependent spatial temperature maps measured with an infrared camera during laser therapy were correlated with post-treatment cell viability distribution maps obtained by cell-staining fluorescent microscopy. Conclusion: The BEAST viability algorithm accurately and rapidly determined the cell viability as a function of time, space and temperature.

Original submitted 13 July 2011; Revised submitted 12 March 2012; Published online 20 July 2012

Reciprocal regulation of annexin A2 and EGFR with Her-2 in Her-2 negative and herceptin-resistant breast cancer

Alternative survival pathways are commonly seen to be upregulated upon inhibition of receptor tyrosine kinases (RTK), including Her-2. It is established that treatment with Herceptin leads to selective overexpression and activation of epidermal growth factor receptor (EGFR) and Src which further contributes to oncogenesis in Herceptin resistant and triple negative breast cancer (TNBC) patients. Here, we show a co-regulated upregulation in the expression of Annexin A2 (AnxA2), a known substrate of Src and one of the regulators of EGFR receptor endocytosis, in Herceptin resistant and Her-2 negative breast cancer. Immunohistochemical expression analysis revealed a reciprocal regulation between Her-2 and AnxA2 in breast cancer clinical samples as well as in cell lines as confirmed by protein and RNA analysis. The siRNA and Herceptin mediated downregulation/inhibition of Her-2 in Her-2 amplified cells induced AnxA2 expression and membrane translocation. In this study we report a possible involvement of AnxA2 in maintaining constitutively activated EGFR downstream signaling intermediates and hence in cell proliferation, migration and viability. This effect was consistent in Herceptin resistant JIMT-1 cells as well as in Her-2 negative breast cancer. The siRNA mediated AnxA2 downregulation leads to increased apoptosis, decreased cell viability and migration. Our studies further indicate the role of AnxA2 in EGFR-Src membrane bound signaling complex and ligand induced activation of downstream signaling pathways. Targeting this AnxA2 dependent positive regulation of EGFR signaling cascade may be of therapeutic value in Her-2 negative breast cancer.

Heat shock protein 90 inhibition: rationale and clinical potential

Heat shock protein 90 (HSP90) is a molecular chaperone protein essential for cellular survival. Functionally, HSPs promote proper protein folding, prevent misfolding, and restore three-dimensional protein structure which is critical following toxic cellular stresses. Recently, targeting HSP90 pharmacologically has gained traction in cancer therapy. Oncogenic cells depend on their ability to withstand endogenous (anoxia, nutrient deprivation, pH changes, and deranged signaling pathways) and exogenous (chemotherapy and radiation therapy) stressors for survival. Pharmacological inhibition of HSP90 destabilizes proteins and leads to degradation through the proteasome. This article will review the utility of HSP90 inhibition, as well as the current adoption in clinical trials and practice.

Loss of HITS (FAM107B) expression in cancers of multiple organs: tissue microarray analysis

Family with sequence similarity 107 (FAM107) proteins consist of two subtypes, FAM107A and FAM107B in mammals, possessing a conserved N-terminal domain of unknown function. Recently we found that FAM107B, an 18 kDa nuclear protein, is expressed in a broad range of tissues and is downregulated in gastrointestinal cancer. Because FAM107B expression is amplified by heat-shock stimulation, we designated it heat shock-inducible tumor small protein (HITS). Although data related to FAM107A as a candidate tumor suppressor have been accumulated, little biological information is available for HITS. In the present study, we examined HITS expression using immunohistochemistry with tissue microarrays and performed detailed statistical analyses. By screening a high-density multiple organ tumor and normal tissue microarray, HITS expression was decreased in tumor tissues of the breast, thyroid, testis and uterine cervix as well as the stomach and colon. Further analysis of tissue microarrays of individual organs showed that loss of HITS expression in cancer tissues was statistically significant and commonly observed in distinct organs in a histological type-specific manner. The HITS expression intensity was inversely correlated with the primary tumor size in breast and thyroid cancers. In addition, effects of tetracycline-inducible HITS expression on tumor growth were investigated in vivo. Forced expression of HITS inhibited tumor xenograft proliferation, compared with the mock-treated tumor xenograft model. These results show that loss of HITS expression is a common phenomenon observed in cancers of distinct organs and involved in tumor development and proliferation.

Increased inducible heat shock protein 72 expression associated with PBMC isolated from patients with haematological tumours

BACKGROUND

Heat shock protein 72 (Hsp72) is a highly inducible stress protein and molecular chaperone. Cancers have been shown to be associated with increased Hsp72 expression within the tumour itself and this may lead to resistance to apoptosis.

METHODS

Peripheral blood mononuclear cells (PBMC) were isolated from patients diagnosed with chronic lymphocytic leukaemia (CLL) (n = 27) and chronic myelomonocytic leukaemia (CMML) (n = 16) and Hsp72 expression was characterized on both the cell surface and intracellularly by flow cytometry. To allow for comparison PBMC from breast cancer patients (n = 25) and healthy volunteers (n = 19) were included.

RESULTS

Both lymphocytes and monocytes from CLL and CMML patients showed high levels of total Hsp72 expression (4-6 fold increase) in comparison to breast cancer and healthy subjects. The majority of Hsp72 in these tumours was determined to be cell-surface expressed (64-93% of cell total Hsp72).

CONCLUSIONS

A correlation was observed between lymphocyte and monocyte total Hsp72 expression (p < 0.001) suggesting a common stress response pathway may exist in these blood cells and there are stress conditions present within the circulation. Hsp72 expression was not found to be related to white blood cell count.

FOXA1: a transcription factor with parallel functions in development and cancer

When aberrant, factors critical for organ morphogenesis are also commonly involved in disease progression. FOXA1 (forkhead box A1), also known as HNF3α (hepatocyte nuclear factor 3α), is required for postnatal survival due to its essential role in controlling pancreatic and renal function. In addition to regulating a variety of tissues during embryogenesis and early life, rescue experiments have revealed a specific role for FOXA1 in the postnatal development of the mammary gland and prostate. Activity of the nuclear hormone receptors ERα (oestrogen receptor α) and AR (androgen receptor) is also required for proper development of the mammary gland and prostate respectively. FOXA1 modulates ER and AR function in breast and prostate cancer cells, supporting the postulate that FOXA1 is involved in ER and AR signalling under normal conditions, and that some carcinogenic processes in these tissues stem from hormonally regulated developmental pathways gone awry. In addition to broadly reviewing the function of FOXA1 in various aspects of development and cancer, this review focuses on the interplay of FOXA1/ER and FOXA1/AR, in normal and cancerous mammary and prostate epithelial cells. Given the hormone dependency of both breast and prostate cancer, a thorough understanding of FOXA1's role in both cancer types is critical for battling hormone receptor-positive disease and acquired anti-hormone resistance.

Structural characterization of tetranortriterpenes from Pseudrocedrela kotschyi and Trichilia emetica and study of their activity towards the chaperone Hsp90

Investigation of roots extracts Pseudrocedrela kotschyi and Trichilia emetica led to identification of 5 limonoid derivatives, Kotschyins D-H, and 11 known compounds. Their structures were elucidated by extensive 1D and 2D NMR experiments in conjunction with mass spectrometry. A surface plasmon resonance (SPR) approach was adopted to screen their Hsp90 binding capability and kotschyin D showed a significant affinity for the chaperone. Therefore, the characterization of the biological activity of kotschyin D by means of a panel of chemical and biological approaches, including limited proteolysis, molecular docking and biochemical and cellular assays, was performed. Our result indicated this compound as a type of client selective Hsp90 inhibitor, directly binding to the middle domain of the protein and possibly preventing its interaction with the activator of Hsp90 ATPase 1 (Aha1).

Nuclear Ago2/HSP60 contributes to broad spectrum of hATSCs function via Oct4 regulation

AIMS

Argonaute2 (Ago2) plays a fundamental role in microRNA-mediated gene regulation through its intrinsic endonuclease activity. In this study we demonstrate the novel functions and molecular mechanisms by which nuclear Ago2 directly regulates HSP (heat shock protein) 60 expression and stem cell self-renewal. HSP60 is a crucial regulator of ROS (reactive oxygen species), senescence, and apoptotic cell death in several tissues and cell types.

RESULTS

HSP60 is regulated via inactivation of p38/JNK and p53 and binds directly to the regulatory regions of the TERT, c-myc, GPx3, p53, and STAT3 genes. Using HSP60 CHIP-PCR experiments, we show that HSP60 binds directly to the Oct4 and Nanog genes and directly regulates Oct4 and other stemness genes involved in human adipose tissue-derived stem cell (hATSC) differentiation. HSP60 also positively regulates ROS-scavenging factors, including GPx3 and TXNL1, which directly modulate cytosolic ROS in hATSCs. Moreover, our study shows that Oct4 regulates HSP60 expression and controls hATSC survival and self-renewal after binding to the HSP60 gene. Furthermore, HSP60-mediated regulation of Oct4 contributes to neuronal and endodermal β-cell differentiation of hATSCs in vitro and in vivo and downregulates mesoderm-specific gene expression.

INNOVATION AND CONCLUSION

We show that increased levels of Ago2 or HSP60 effectively induce nuclear localization of HSP60, which directly controls Oct4, c-Myc, p53, TERT, and STAT3 for transdifferentiation programs. Collectively, we suggest a novel model in which nuclear Ago2 controls HSP60 in hATSCs.

Variations in HSPA1B at 6p21.3 are associated with lung cancer risk and prognosis in Chinese populations

The heat shock protein Hsp70 is crucial for regulating cellular homeostasis in stressed cells. Although the tumorigenic potential and prognostic applications of Hsp70 have been widely investigated, it remains unclear whether genetic variations of the human isoforms HSPA1L, HSPA1A, and HSPA1B are associated with cancer risk and prognosis. In this study, we genotyped six tagSNPs in these genes in 1,152 paired patients with lung cancer and controls, and then validated the results in additional cohorts of 1,781 patients with lung cancer and 1,038 controls. In addition, we evaluated the associations of these tagSNPs with survival in 330 patients with advanced non-small cell lung cancer (NSCLC) with additional validation in another 331 patients with advanced NSCLC. Functions of the risk variants identified were investigated using cell-based reporter assays. We found that the HSPA1B rs6457452T allele was associated with increased lung cancer risk compared with the rs6457452C allele in both data sets and also pooled analysis (adjusted OR = 1.41; P = 2.8 × 10(-5)). The HSPA1B rs2763979TT genotype conferred poor survival outcomes for patients with advanced NSCLC in two independent cohorts and pooled analysis [adjusted hazard ratio (HR) = 1.80, 1.61, and 1.66; P = 0.013, 0.036, and 0.002, respectively]. Lastly, we also found that the rs2763979T and rs6457452T alleles were each sufficient to reduce expression of transcriptional reporter constructs, when compared with the rs2763979C and rs6457452C alleles, respectively. Taken together, our findings define that functional HSPA1B variants are associated with lung cancer risk and survival. These Hsp70 genetic variants may offer useful biomarkers to predict lung cancer risk and prognosis.

Heat shock protein as molecular targets for breast cancer therapeutics

Recent advances in the understanding of the molecular mechanisms involved in the breast cancer development and progression have led to the identification of numerous novel molecular targets. Among these, heat shock proteins (HSPs) are being emerging molecular target due to its diverse function in cancer cells. HSPs are highly conserved molecular chaperone that are synthesized by cell in response to various stress conditions. Mammalian HSPs have been classified into several families according to their molecular weight: HSP100, HSP90, HSP72, and small molecular HSPs (including HSP27). They are essential proteins that play a key role in cell survival through the cytoprotective mechanisms. In addition, HSPs are often overexpressed in a rage of cancers including breast cancer, and its overexpression seems to be associated with poor clinical outcomes. Also, HSP90 play a role in facilitating transformation by stabilizing the mutated and overexpressed oncoproteins found in breast cancer cell. Pharmacological targeting of HSP is therefore indicated and in the case of HSP90, numerous inhibitory drugs are undergoing clinical trial for treatment of breast cancer and other cancers. In this review, we describe the roles of HSPs in cancer cell and introduce the HSPs inhibitor as molecular target in cancer therapy and its recent clinical trials in breast cancer.

Evaluation of hepatitis B viral replication and proteomic analysis of HepG2.2.15 cell line after knockdown of HBx

BACKGROUND

Hepatitis B virus (HBV) is one of the major pathogens of human liver disease. Studies have shown that HBV X protein (HBx) plays an important role in promoting viral gene expression and replication. In this study we performed a global proteomic profiling to identify the downstream functional proteins of HBx, thereby detecting the mechanisms of action of HBx on virion replication.

METHODS

HBx in the HepG2.2.15 cell line was knocked down by the transfection of small interfering RNA (siRNA). The replication level of HBV was evaluated by microparticle enzyme immunoassay analysis of HBsAg and HBeAg in the culture supernatant, and real-time quantitative PCR analysis of HBV DNA. Two-dimensional electrophoresis combined with MALDI-TOF/TOF was performed to analyze the changes in protein expression profile after treatment with HBx siRNA.

RESULTS

Knockdown of HBx disturbed HBV replication in vitro. HBx target siRNA significantly inhibited the expression of HBsAg, HBeAg and the replication of HBV DNA. Twelve significantly changed proteins (7 upregulated and 5 downregulated) were successfully identified by MALDI-TOF/TOF using proteomics differential expression analysis after the knockdown of HBx. Among these identified proteins, HSP70 was validated by Western blotting.

CONCLUSION

The results of the study indicated the positive effect of HBx on HBV replication, and a group of downstream target proteins of HBx may be responsible for this effect.

Using proteomic approach to identify tumor-associated proteins as biomarkers in human esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is one of the most common cancers in China. The lower survival rate of ESCC is attributed to late diagnosis and poor therapeutic efficacy; therefore, the identification of tumor-associated proteins as biomarkers for early diagnosis, and the discovery of novel targets for therapeutic intervention, seems very important for increasing the survival rate of ESCC. To identify tumor-associated proteins as biomarkers in ESCC, we have analyzed ESCC tissues and adjacent normal tissues by two-dimensional electrophoresis (2DE) and matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) analysis. The results showed that a total of 104 protein spots with different expression levels were found on 2DE, and 47 proteins were eventually identified by MALDI-TOF MS. Among these identified proteins, 33 proteins including keratin 17 (KRT17), biliverdin reductase B (BLVRB), proteasome activator subunit 1 (PSME1), manganese superoxide dismutase (MnSOD), high-mobility group box-1(HMGB1), heat shock protein 70 (HSP70), peroxiredoxin (PRDX1), keratin 13 (KRT13), and so on were overexpressed, and 14 proteins including cystatin B (CSTB), tropomyosin 2 (TPM2), annexin 1 (ANX1), transgelin (TAGLN), keratin 19 (KRT19), stratifin (SFN), and so on were down-expressed in ESCC. Biological functions of these proteins are associated with cell proliferation, cell motility, protein folding, oxidative stress, and signal transduction. In the subsequent study using immunoassay on ESCC serum samples and tissue-array slides, two representative proteins, HSP70 and HMGB1, were selected as examples for the purpose of validation. The results showed that both HSP70 and HMGB1 can induce autoantibody response in ESCC sera and have higher expression in ESCC tissues. Especially, the frequency of antibodies to HSP70 in ESCC sera was significantly higher than that in normal human sera. The preliminary results suggest that some of these identified proteins might contribute to esophageal cell differentiation and carcinogenesis, certain proteins could be used as tumor-associated antigen (TAA) biomarkers in cancer diagnosis, and further studies on these identified proteins should provide more evidence of how these proteins are involved in carcinogenesis of ESCC.

Prognostic significance of heat shock protein 70 (HSP70) in patients with oral cancer

Backround

Oral squamous cell carcinoma (OSCC) is characterized by an aggressive growth pattern, local invasiveness, and spread to cervical lymph nodes. Overall survival rates have not improved, primarily due to locoregional tumor recurrences and distant metastasis. To date, no trustworthy or clinically applicable marker of tumor aggressiveness has been identified for OSCC. Heat shock proteins (HSPs) play a role in tumor antigenicity. This study aimed to investigate the expression and prognostic significance of highly stress-inducible HSP70 in OSCC.

Methods

Immunohistochemical staining for HSP70 was performed on surgical specimens obtained from 61 patients with OSCC. Light microscopy and analysis 3.1^® (Soft Imaging System, Münster, Germany), an image processing and analysis program, were used for evaluating HSP70 expression. The tumor region was defined as the region of interest (ROI) and HSP70-positive staining was analyzed.

Results

Immunoreactivity for HSP70 was positive in tumor cells of 38 of all patients (63.3%). Positive immunoreactivity of tumor cells could be detected in 17 of 28 patients with T2 tumors (60.7%) Prognostic significance of HSP70 expression in tumor cells was detected in patients with T2 tumors (p = 0.009).

Conclusions

The survival of patients suffering from T2 tumors with positive HSP70 expression was 8 times higher than that for patients with negative HSP70 expression, suggesting that T1-T2 tumors of OSCC with low expression of HSP70 require more radical treatment.

Inhibition of heat shock protein 90 (HSP90) as a therapeutic strategy for the treatment of myeloma and other cancers

Heat shock protein 90 (HSP90) is a molecular chaperone that is induced in response to cellular stress and stabilizes client proteins involved in cell cycle control and proliferative/anti-apoptotic signalling. HSP90 is overexpressed in a range of cancers, and may contribute to tumour cell survival by stabilizing aberrant signalling proteins and by interfering with apoptosis. Tanespimycin, an HSP90 inhibitor, reduces tumour cell survival in vitro. In multiple myeloma (MM), HSP90 inhibition affects multiple client proteins that contribute to tumour cell survival, including the IGF1 receptor and the IL-6 receptor, and elements of the PI3/Akt, STAT3, and MAPK signalling pathways. HSP90 inhibition also abrogates the protective effect of bone marrow stromal cells and inhibits angiogenesis and osteoclastogenesis. Tanespimycin acts synergistically with the proteasome inhibitor bortezomib in MM cells and tumour explants, possibly reducing their ability to resist bortezomib-induced stress to the endoplasmic reticulum. The combination of tanespimycin and bortezomib has demonstrated significant and durable responses with acceptable toxicity in a phase I/II study in patients with relapsed and relapsed/refractory MM. HSP90 inhibition is a promising strategy in MM especially in combination with bortezomib; additional studies will further evaluate optimal dosings of candidate drugs and schedules, as well as confirm efficacy in comparative phase III trials.

Photothermal response of human and murine cancer cells to multiwalled carbon nanotubes after laser irradiation

This study demonstrates the capability of multiwalled carbon nanotubes (MWNTs) coupled with laser irradiation to enhance treatment of cancer cells through enhanced and more controlled thermal deposition, increased tumor injury, and diminished heat shock protein (HSP) expression. We also explored the potential promise of MWNTs as drug delivery agents by observing the degree of intracellular uptake of these nanoparticles. To determine the heat generation capability of MWNTs, the absorption spectra and temperature rise during heating were measured. Higher optical absorption was observed for MWNTs in water compared with water alone. For identical laser parameters, MWNT-containing samples produced a significantly greater temperature elevation compared to samples treated with laser alone. Human prostate cancer (PC3) and murine renal carcinoma (RENCA) cells were irradiated with a 1,064-nm laser with an irradiance of 15.3 W/cm(2) for 2 heating durations (1.5 and 5 minutes) alone or in combination with MWNT inclusion. Cytotoxicity and HSP expression following laser heating was used to determine the efficacy of laser treatment alone or in combination with MWNTs. No toxicity was observed for MWNTs alone. Inclusion of MWNTs dramatically decreased cell viability and HSP expression when combined with laser irradiation. MWNT cell internalization was measured using fluorescence and transmission electron microscopy following incubation of MWNTs with cells. With increasing incubation duration, a greater number of MWNTs were observed in cellular vacuoles and nuclei. These findings offer an initial proof of concept for the application of MWNTs in cancer therapy.

Prognostic relevance of Bmi-1 expression and autoantibodies in esophageal squamous cell carcinoma

Background

Overexpression of Bmi-1 has been observed in a variety of cancers, and it has been suggested to be an independent prognostic marker for the patients. The objective of this study was to determine the level of Bmi-1 expression or its autoantibodies in human esophageal squamous cell carcinoma (ESCC) and to correlate it with clinicopathologic data.

Methods

We first examined Bmi-1 expression in ESCC cell lines and tumor samples by RT-PCR and Western blot analysis. We then analyzed Bmi-1 protein expression in 171 clinicopathologically characterized ESCC cases by immunohistochemistry. In addition, we detected its autoantibodies in sera of patients with ESCC by ELISA.

Results

We found that Bmi-1 expression was higher in the immortalized cells, cancer cell lines and most cancer tissue than in non-tumorous control tissue at both mRNA and protein level. In addition, Bmi-1 expression was observed in 64.3% (110 of 171) archive ESCC specimen by immunohistochemistry analysis, and the location of Bmi-1 in ESCC was in the nuclei instead of cytoplasm of tumor cells. There was a significant difference of Bmi-1 expression in patients categorized according to stage (P = 0.003) and pN classification (P = 0.047). Multivariate analysis suggested that Bmi-1 expression was an independent prognostic marker for ESCC patients. A prognostic significance of Bmi-1 was also found in the subgroup of T3~T4 and N1 tumor classification. Bmi-1 autoantibodies were detected in sera of 39.0% (62 of 159) ESCC patients. The correlations between anti-Bmi-1 antibodies and tumor stage (P = 0.040), or lymph node status (P < 0.001) were significant.

Conclusions

Our results suggest that Bmi-1 protein is a valuable marker of ESCC progression. The presence of Bmi-1 autoantibodies in sera from patients with ESCC may have clinical utility in esophageal cancer diagnosis.

Photothermal response of tissue phantoms containing multi-walled carbon nanotubes

Inclusion of multi-walled carbon nanotubes (MWNTs) into tissue prior to laser therapy has the potential to enhance the selectivity and effectiveness of cancer therapy by providing greater and more controlled thermal deposition. The purpose of this study was to investigate the optical and thermal response of tissue representative phantoms containing MWNTs to optical radiation. Tissue representative phantoms 20 mm in diameter and 1 mm in thickness were created from sodium alginate. Following the inclusion of MWNTs (900 nm in length, 40-60 nm in diameter) in phantoms, the distribution of MWNTs was observed using transmission electron microscopy. A predominantly, evenly dispersed and randomly oriented distribution of MWNTs was observed with a rare presence of MWNT clustering or clumping. In order to characterize the response of MWNT inclusion on optical properties of phantoms, the transmittance and reflectance spectra of phantoms with and without MWNT inclusion were measured with a spectrophotometer over a wavelength range of 200-1400 nm. Inclusion of MWNTs in phantoms dramatically enhanced light absorption across the entire wavelength range as evidenced by a diminished transmittance and reflectance compared with phantoms without MWNTs. In order to evaluate the spatiotemporal temperature distribution associated with laser irradiation of phantoms with and without MWNTs, the temperature was measured at discrete radial distances from the center of the incident laser beam using thermocouples. The rate of temperature increase and peak temperature for phantoms containing MWNTs was much greater compared with phantoms without MWNTs at all measurement locations. In conclusion, MWNT inclusion in tissue phantoms increases the optical absorption and temperature elevation, which may enable more effective photothermal therapies of human disease utilizing lasers.

Quercetin suppresses HeLa cell viability via AMPK-induced HSP70 and EGFR down-regulation

Quercetin, an anti-oxidant flavonoid that is widely distributed in the plant kingdom, has been suggested to have chemopreventive effects on cancer cells, although the mechanism is not completely understood. In this study, we found that quercetin increased the phosphorylation of AMP-activated protein kinase (AMPK) and downstream acetyl-CoA carboxylase (ACC) and suppressed the viability of HeLa cells. AICAR, an AMPK activator, and quercetin down-regulated heat shock protein (HSP)70 and increased the activity of the pro-apoptotic effector, caspase 3. Knock-down of AMPK blocked quercetin-mediated HSP70 down-regulation. Moreover, knock-down of HSP70 enhanced quercetin-mediated caspase 3 activation. Furthermore, quercetin sustained epidermal growth factor receptor (EGFR) activation by suppressing the phosphatases, PP2a and SHP-2. Finally, quercetin increased the interaction between EGFR and Cbl, and also induced the tyrosine phosphorylation of Cbl. Together, these results suggest that quercetin may have anti-tumor effects on HeLa cells via AMPK-induced HSP70 and down-regulation of EGFR.

Facilitating Akt clearance via manipulation of Hsp70 activity and levels

Members of the 70-kDa heat shock family can control and manipulate a host of oncogenic client proteins. This role of Hsp70 in both the folding and degradation of these client proteins makes it a potential drug target for certain forms of cancer. The phenothiazine family of compounds, as well as the flavonoid myricetin, was recently shown to inhibit Hsp70-ATPase activity, whereas members of the dihydropyrimidine family stimulated ATPase function. Akt, a major survival kinase, was found to be under the regulation of Hsp70, and when the ATPase activity of Hsp70 was increased or decreased by these compounds, Akt levels were also increased or decreased. Also, increasing Hsp70 levels concurrent with inhibition of its ATPase function synergistically reduced Akt levels to a greater extent than either manipulation alone, providing new insights about client fate decisions. Akt reductions mediated by Hsp70 inhibitors were prevented when Hsp70 expression was silenced with small interfering RNA. Inhibiting Hsp70 ATPase function produced cytotoxic events only in breast cancer cell lines where Akt dysfunction was previously shown, suggesting therapeutic specificity depending on the Hsp70 client profile. Thus, increasing Hsp70 levels combined with inhibiting its ATPase function may serve to dramatically reduce Akt levels and facilitate cell death in certain types of cancer.

Regulation of heat shock gene transcription in neuronal cells

The heat shock protein (HSP) molecular chaperones are the primary cellular defense against damage to the proteome, initiating refolding of denatured proteins and regulating degradation after severe protein damage. Many neurodegenerative disorders involve aberrant protein folding and protein damage, which accumulates in an age-dependent manner. Ageing is associated with the decrease in activity of the heat shock transcription factors (HSF) that regulate HSP gene transcription. Neuronal cells seem particularly vulnerable in this sense as HSF activity and HSP expression are relatively weak in such cells and motor neurons appear to require input of HSP secreted from adjacent glial cells to maintain adequate molecular chaperone levels. It may be significant that motor neurons have been shown to be the sensitive cells in the ageing of Drosophila and C. elegans and that these organisms may acquire extended lifespans with over-expression of small heat shock proteins and HSF1. HSF1 transcriptional activity has been discussed in neuronal cells, concentrating on the regulation and activity of HSF1 and HSF2 and their role in HSP expression, during neurodegenerative diseases and as mediators of cell survival.

The metal-binding domain of IGFBP-3 selectively delivers therapeutic molecules into cancer cells

Conventional chemotherapy for cancer has limited specificity for cancer cells. Here, we investigate the possibility of improving the selectivity of chemotherapy by coadministering targeted biological modifier peptides. We show that the 22-amino acid metal-binding transporter domain (MBD) derived from insulin-like growth factor-binding protein-3 selectively targets cancer cells. The rate of MBD uptake by cells was measured using a panel of 54 human cancer cell lines and correlated with MBD cross-linking to cell surface transferrin receptor, caveolin 1, and integrin beta. Gene array data show that MBD uptake correlates with the expression of genes associated with cellular stress-coping mechanisms commonly upregulated in cancer (nuclear factor-kappaB, Hsp-70B). MBD-tagged peptides designed to inhibit such mechanisms have cytotoxic effects on a broad range of human cancer cell lines. The discriminant validity of these peptides as potential cotherapeutic agents was investigated by comparing their cytotoxicity to cancer cell lines versus normal human cell counterparts. Synergies between these peptides and marginally cytotoxic levels of 5-fluorouracil were demonstrated. Biodistribution data from in-vivo experiments in mice and rats confirm that MBD-tagged peptides and proteins preferably localize to specific tissues, such as kidney and pancreas. Intracardial injection of CCRF-CEM T-cell leukemia or MDA-MB-435 cells into Rag-2 mice establishes disseminated disease within 7 days. Twenty-five-day subcutaneous administration of a three-peptide cocktail (3 mg/kg) in combination with 5-fluorouracil in Rag-2 mice with established CCRF-CEM leukemia significantly reduces splenomegaly and bone marrow cancer cell burden. In a similar experiment using MDA-MB-435 cells, MBD-tagged peptides reduced human cell burden in bone marrow. Taken together, these data suggest that MBD-tagged molecules can be used as highly selective chemosensitizers in the treatment of hematological and disseminated malignancies.

HspBP1 levels are elevated in breast tumor tissue and inversely related to tumor aggressiveness

HspBP1 is a co-chaperone that binds to and regulates the chaperone Hsp70 (Hsp70 is used to refer to HSPA1A and HSPA1B). Hsp70 is known to be elevated in breast tumor tissue, therefore the purpose of these studies was to quantify the expression of HspBP1 in primary breast tumors and in serum of these patients with a follow-up analysis after 6 to 7 years. Levels of HspBP1, Hsp70, and anti-HspBP1 antibodies in sera of breast cancer patients and healthy individuals were measured by enzyme-linked immunosorbent assay. Expression of HspBP1 was quantified from biopsies of tumor and normal breast tissue by Western blot analysis. The data obtained were analyzed for association with tumor aggressiveness markers and with patient outcome. The levels of HspBP1 and Hsp70 were significantly higher in sera of patients compared to sera of healthy individuals. HspBP1 antibodies did not differ significantly between groups. HspBP1 levels were significantly higher in tumor (14.46 ng/microg protein, n = 51) compared to normal adjacent tissue (3.17 ng/microg protein, n = 41, p < 0.001). Expression of HspBP1 was significantly lower in patients with lymph node metastasis and positive for estrogen receptors. HspBP1 levels were also significantly lower in patients with a higher incidence of metastasis and death following a 6 to 7-year follow-up. The HspBP1/Hsp70 molar ratio was not associated with the prognostic markers analyzed. Our results indicate that low HspBP1 expression could be a candidate tumor aggressiveness marker.