Use Of Heat Shock Proteins Research Articles

Functions and Therapeutic Use of Heat Shock Proteins in Hepatocellular Carcinoma

Heat shock proteins are intracellular proteins expressed in prokaryotes and eukaryotes that help protect the cell from stress. They play an important role in regulating cell cycle and cell death, work as molecular chaperons during the folding of newly synthesized proteins, and also in the degradation of misfolded proteins. They are not only produced under stress conditions like acidosis, energy depletion, and oxidative stress but are also continuously synthesized as a result of their housekeeping functions. There are different heat shock protein families based on their molecular weight, like HSP70, HSP90, HSP60, HSP27, HSP40, etc. Heat shock proteins are involved in many cancers, particularly hepatocellular carcinoma, the main primary tumor of the liver in adults. Their deregulations in hepatocellular carcinoma are associated with metastasis, angiogenesis, cell invasion, and cell proliferation and upregulated heat shock proteins can be used as either diagnostic or prognostic markers. Targeting heat shock proteins is a relevant strategy for the treatment of patients with liver cancer. In this review, we provide insights into heat shock proteins and heat shock protein-like proteins (clusterin) in the progression of hepatocellular carcinoma and their use as therapeutic targets.

Identification of Hsp90 inhibitors from Ananas comosus potential phytochemicals for lung cancer treatment

Lung cancer is a significant global health issue, with thousands of lives lost each year. One potential approach to preventing lung cancer is the use of heat shock protein 90 (Hsp90) inhibitors, which have been shown to induce substantial cell death in both chemo-sensitive and chemo-resistant small cell lung cancer cells. In this study, we conducted in silico computational molecular docking of pineapple phytochemicals with Hsp90 to investigate their potential inhibitory effects on Hsp90 and, consequently, their ability to prevent lung cancer. Our findings demonstrate that the phytochemicals found in Ananas comosus, specifically caffeic acid, ferulic acid, 4-Hydroxycinnamic acid, Sinapic acid, and D-Galacturonic Acid, exhibit notable inhibitory activity against Hsp90. Beyond their Hsp90 inhibition, these phytochemicals also demonstrate promising biological activities, serving as effective agents against neoplastic conditions, particularly lung cancer, and displaying pro-apoptotic properties. Moreover, the ADME (Absorption, Distribution, Metabolism, and Excretion) and toxicological assessments conducted on these compounds yielded satisfactory results. These findings suggest that pineapple phytochemicals may have potential in the development of novel therapeutic strategies for lung cancer prevention.

Heat Shock Proteins in Сancer Diagnostics

With the growing number of cancers, new assistive tools are required to obtain extensive molecular profiles of patients to help identify the disease. Early diagnosis of cancer is based on the analysis of relevant biomarkers, which can be used to monitor the population in order to identify the disease until it can be determined using standard methods and is not clinically manifest. One of the potential markers of cancer is heat shock proteins that act as molecular chaperones. Changes in heat shock proteins expression can serve as an important diagnostic marker of the cell’s response to damage. The paper presents a brief overview of the prevalence of oncological diseases in the world, the need of early oncological diagnostics development, as well as the prospects for the use of heat shock proteins in making an oncological diagnosis.

Immunological aspects of heat shock protein functions and their significance in the development of cancer vaccines

The primary function of intracellular heat shock proteins (HSPs) is to protect the cell by suppressing the effects of va­rious stress factors by either refolding misfolded proteins or blocking apoptosis. After neoplastic transformation, cells overexpress HSPs, which act as factors promoting the neoplastic process by stabilizing proteins responsible for carci­nogenesis, however, HSPs can be released into the extracellular environment where they act as important modulators of the immune response. In a tumor microenvironment, extracellular HSPs are able to induce a pro- or anti-neoplastic response, using various mechanisms of affecting immune cells, The study of the role of extracellular HSPs in immuno­modulation processes is a very important direction in the search for new methods of cancer treatment. This review summarizes reports on the use of HSPs in immunotherapeutic cancer strategies, in particular in cancer vaccine design.

A Review of Heat Shock Proteins Research on <i>Bemisia tabaci</i>

Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) is the most destructive invasive pests in agricultural production and has a high tolerance to heat. Heat shock proteins play an essential role in life activities such as growth and development, reproduction and diapause of B. tabaci. At the same time, they are also crucial in resisting adverse environments and in adaptive evolution. The expression of heat shock protein in B. tabaci is not only related to temperature, but also to the tolerance of the environment. After receiving external stimuli, the expression level can be increased or decreased to maintain the stability of cells in vivo. This paper reviews the classification, biological characteristics, biological functions, and research status of HSPs in recent years. This mini-review will provide helpful information related to the use of heat shock proteins to study the occurrence and damage of B. tabaci. This has important theoretical and practical significance for revealing Hsps in explaining the population expansion mechanism of B. tabaci invasion and predicting population dynamics.

Heat Shock Proteins in Urine as Cancer Biomarkers.

Heat shock proteins (HSPs) are a large family of molecular chaperones, which have shown to be implicated in various hallmarks of cancer such as resistance to apoptosis, invasion, angiogenesis, induction of immune tolerance, and metastasis. Several studies reported aberrant expression of HSPs in liquid biopsies of cancer patients and this has opened new perspectives on the use of HSPs as biomarkers of cancer. However, no specific diagnostic, predictive, or prognostic HSP chaperone-based urine biomarker has been yet discovered. On the other hand, divergent expression of HSPs has also been observed in other pathologies, including neurodegenerative and cardiovascular diseases, suggesting that new approaches should be employed for the discovery of cancer-specific HSP biomarkers. In this study, we propose a new strategy in identifying cancer-specific HSP-based biomarkers, where HSP networks in urine can be used to predict cancer. By analyzing HSPs present in urine, we could predict cancer with approximately 90% precision by machine learning approach. We aim to show that coupling the machine learning approach and the understanding of how HSPs operate, including their functional cycles, collaboration with and within networks, is effective in defining patients with cancer, which may provide the basis for future discoveries of novel HSP-based biomarkers of cancer.

Large within, and between, species differences in marine cellular responses: Unpredictability in a changing environment

Predicting the impacts of altered environments on future biodiversity requires a detailed understanding of organism responses to change. To date, studies evaluating mechanisms underlying marine organism stress responses have largely concentrated on oxygen limitation and the use of heat shock proteins as biomarkers. However, whether these biomarkers represent responses that are consistent across species and different environmental stressors remains open to question. Here we show that responses to four different thermal stresses (three rates of thermal ramping (1 °C h−1, 1 °C day−1 or 1 °C 3 day−1) and a three-month acclimation to warming of 2 °C) applied to three species of Antarctic marine invertebrate produced highly individual responses in gene expression profiles, both within and between species. Mapping the gene expression profiles from each treatment for each of the three species, identified considerable difference in numbers of differentially regulated transcripts ranging from 10 to 3011. When these data were correlated across the different temperature treatments, there was no evidence for a common response with only 0–2 transcripts shared between all four treatments within any one species. There were also no shared differentially expressed genes across species, even at the same thermal ramping rates. The classical cellular stress response (CSR) i.e. up-regulation of heat shock proteins, was only strongly present in two species at the fastest ramping rate of 1 °C h−1, albeit with different sets of stress genes expressed in each species. These data demonstrate the wide variability in response to warming at the molecular level in marine species. Therefore, identification of biodiversity stress responses engendered by changing conditions will require evaluation at the species level using targeted key members of the ecosystem, strongly correlated to the local biotic and abiotic factors.

The role of heat shock proteins in neoplastic processes and the research on their importance in the diagnosis and treatment of cancer.

Heat shock proteins (HSPs) are chaperones with highly conservative primary structure, necessary in the processes of protein folding to the most energetically advantageous conformation and maintaining their stability. HSPs perform a number of important functions in various cellular processes and are capable of modulating pathophysiological conditions at the cellular and systemic levels. An example is the high level of HSP expression in neoplastic tissues, which disrupts the apoptosis of transformed cells and promotes the processes of proliferation, invasion, and metastasis. In addition, an increasing amount of information is appearing about the participation of HSPs in the formation of multidrug resistance.This paper provides a review of the current state of research on the fundamental importance as well as the diagnostic and prognostic role of various classes of HSP in cancer treatment. It presents the prospects for using HSPs as biological markers of disease progression and targets in various cancer treatment strategies. However, the need for additional research is quite high. Only numerous joint efforts of research groups will allow the effective use of HSPs as a tool to combat cancer.

Promising Scaffold-Free Approaches in Translational Dentistry.

Regenerative medicine has recently improved the principal therapies in several medical fields. In the past ten years, the continuous search for novel approaches to treat the most common dental pathologies has developed a new branch called regenerative dentistry. The main research fields of translational dentistry involve biomimetic materials, orally derived stem cells, and tissue engineering to populate scaffolds with autologous stem cells and bioactive growth factors. The scientific literature has reported two main research trends in regenerative dentistry: scaffold-based and scaffold-free approaches. This article aims to critically review the main biological properties of scaffold-free regenerative procedures in dentistry. The most impactful pros and cons of the exosomes, the leading role of hypoxia-based mesenchymal stem cells (MSCs), and the strategic use of heat shock proteins in regenerative dentistry will be highlighted and discussed in terms of the use of such tools in dental regeneration and repair.

The next generation of peptide receptor radionuclide therapy

Peptide receptor radionuclide therapy (PRRT) with [177Lu]Lu-DOTA-[Tyr3]octreotate has been successfully developed in the last decades for the treatment of neuroendocrine neoplasms. However, different methods to improve the objective response rate and survival are under investigation. This includes changes of the radioligand, dosimetry and combination therapy with different agents, such as radiosensitisers. Hofving et al. recently reported, in the April 2019 issue of Endocrine-Related Cancer, the use of heat-shock protein 90 (Hsp90) modulation to augment radiation effects as a new promising target for radiosensitisation. In this commentary, new developments in the field of PRRT are discussed, placing these new findings about Hsp90 inhibitors into context.

Thermostable Vaccines: Past, Present and Future Perspectives

Vaccines stability has a major role in the success of immunization programs and saves millions of livesevery year. To stabilize vaccines cold chains are developed for storage and transport, as efficiency ofvaccines is hampered if they are not kept under proper temperature. Aluminum is used for making vaccinethermostable. The development of vaccine formulation is a critical part of overall development cycle ofapproving, testing and producing new vaccines. However, Liquid vaccine formulation is still preferred overdry formulation because of ease in using, packaging and manufacturing. Other approaches have beenused to make vaccine thermostable. This study demonstrates those processes, used to develop thermosensitivevaccines into thermostable vaccine and also describes vaccine formulation designing and useof heat shock protein including mHSP70 and mHSP65 to generate innate and adaptive immune response.

Heat Shock Proteins and their Protective Roles in Stem Cell Biology.

Stem cells (SCs) are discovered long back but the idea that SCs possess therapeutic potential came up just a few decades back. In a past decade stem cell therapy is highly emerged and displayed tremendous potential for the treatment of a wide range of diseases and disorders such as blindness and vision impairment, type I diabetes, infertility, HIV, etc. SCs are very susceptible to destruction after transplantation into the host because of the inability to sustain elevated stress conditions inside the damaged tissue/organ. Heat shock proteins (HSPs) are molecular chaperones/stress proteins expressed in response to stress (elevated temperature, harmful chemicals, ischemia, viruses, etc) inside a living cell. HSPs protect the cell from damage by assisting in the proper folding of cellular proteins. This review briefly summarises different types of HSPs, their classification, cellular functions as well as the role of HSPs in regulating SC self-renewal and survival in the transplanted host. Applications of HSP modulated SCs in regenerative medicine and for the treatment of ischemic heart disease, myocardial infarction (MI), osteoarthritis, ischemic stroke, spinocerebellar ataxia type 3 (SCA3), leukemia, hepatic ischemia-reperfusion injury, Graft-versus-host disease (GVHD) and Parkinson's disease (PD) are discussed. In order to provide potential insights in understanding molecular mechanisms related to SCs in vertebrates, correlations between HSPs and SCs in cnidarians and planarians are also reviewed. There is a need to advance research in order to validate the use of HSPs for SC therapy and establish effective treatment strategies.

Concomitant use of heat-shock protein 70, glutamine synthetase and glypican-3 is useful in diagnosis of HBV-related hepatocellular carcinoma with higher specificity and sensitivity.

Hepatocellular carcinoma is the third leading cause of cancer-related death worldwide and late diagnosis is the main cause of death in HCC patients. In this study expression patterns of HSP70, GPC3 and GS and their relationships with pathogenesis of HCC in Iranian patients were investigated. The expression of HSP70, GPC3 and GS were determined by immunohistochemistry and quantitative real-time PCR (q-PCR) methods, using 121 cases from patients with HBV alone, HCC without HBV, HBV+HCC and 30 normal tissues as control group. HSP70, GPC3 and GS were expressed in higher levels in HBV-related HCC samples compared to HBV alone group. The results showed that the labeling index of HSP70, GPC3 and GS are correlated with immunohistochemical and molecular expressions of HSP70, GPC3 and GS. The sensitivity and specificity for HCC diagnosis were 43.4% and 89.7% for HSP70, 64.3% and 90.4% for GPC3, and 60.7% and 94.3% for GS, respectively. The sensitivity and specificity of the panels with 3, 2 and 1 positive markers, regardless of which one, were 21.6% and 100%, 51.3% and 100% and 93.4% and 80.5% respectively. The current study demonstrated an association between HSP70, GPC3 and GS expressions and HBV-related HCC in our population. It was concluded that HSP70, GPC3 and GS expressions could be useful biomarkers for increasing the specificity and sensitivity of HCC diagnosis to acceptable level. Also, proper combinations of these 3 markers could improve diagnostic accuracy.

Abstract 4152: The p90RSK-CDC25C signaling pathway leads to bypass of the ganetespib induced G2/M arrest and mediates acquired resistance to ganetespib in KRAS mutant NSCLC

Abstract Lung cancer is the leading cause of cancer death in the United States and worldwide. A large fraction of non-small cell lung cancers (NSCLC) are dependent upon oncogenic driver mutations of which the most commonly observed driver is mutant KRAS. Unfortunately, NSCLC patients with oncogenic KRAS mutations have no effective therapies and prognosis is poor. As direct RAS targeting has been unsuccessful in the clinic to date, use of Heat shock protein 90 (Hsp90) inhibitors in KRAS mutant NSCLC appeared to be promising approach for targeting KRAS mutant NSCLC through its downstream effectors. However, limited clinical efficacy as monotherapy was observed due to rapid resistance. Furthermore, the combination of ganetespib and docetaxel was recently tested in a large phase III clinical trial (Galaxy-2) in advanced lung cancer and failed to demonstrate benefit. Here, we investigated the mechanism(s) of resistance to the Hsp90 inhibitor (Hsp90i), ganetespib by generating NSCLC cells with acquired resistance to Hsp90i’s including ganetespib (GR cells). We have not only identified the mechanism of acquired resistance to ganetespib but have also found that this mechanism induces cross resistance to docetaxel. Finally, we have identified novel Hsp90i combinations that can overcome and prevent this resistance. We report that hyperactivation of ERK and p90RSK and its downstream target, CDC25C leads to acquired resistance to ganetespib and docetaxel. Moreover, this resistance is mediated via bypass of a G2/M arrest. Overexpression of either p90RSK or CDC25C in naïve cells was sufficient to induce the bypass of this G2/M arrest as well induced resistance to both ganetespib and docetaxel. Remarkably, p90RSK or CDC25C overexpression also led to ganetespib resistance in vivo. The observed resistance was dependent on continued p90RSK/CDC25C signaling, as synthetic lethality to specific ERK, p90RSK or CDC25C inhibitors was observed. Importantly, we have found that the combination of ganetespib with inhibitors of ERK1/2, p90RSK, or CDC25C was highly efficacious. In summary, we propose that the hyperactivation of p90RSK induces CDC25C overexpression and activity which then induces G2/M progression via CyclinB1/cdc2 regulation resulting in ganetespib resistance. Despite two decades of testing in the clinic, either as monotherapy or in combination with chemotherapy, Hsp90 inhibitors have been ineffective due to acquired resistance. Our preclinical analyses provide a way forward for Hsp90 inhibitors through the development of novel rationally designed Hsp90 inhibitor combinations that may prevent or overcome resistance to Hsp90 inhibitors. Citation Format: Suman Chatterjee, Eric H. Huang, Ian Christie, Timothy F. Burns. The p90RSK-CDC25C signaling pathway leads to bypass of the ganetespib induced G2/M arrest and mediates acquired resistance to ganetespib in KRAS mutant NSCLC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4152. doi:10.1158/1538-7445.AM2017-4152

Cytotoxic effects of the newly-developed chemotherapeutic agents 17-AAG in combination with oxaliplatin and capecitabine in colorectal cancer cell lines.

The use of heat shock protein 90 inhibitors like 17-allylamino-17-demethoxy-geldanamycin (17-AAG) has been recently introduced as an attractive anticancer therapy. It has been shown that 17-AAG may potentiate the inhibitory effects of some classical anticolorectal cancer (CRC) agents. In this study, two panels of colorectal carcinoma cell lines were used to evaluate the effects of 17-AAG in combination with capecitabine and oxaliplatin as double and triple combination therapies on the proliferation of CRC cell lines. HT-29 and all HCT-116 cell lines were seeded in culture media in the presence of different doses of the mentioned drugs in single, double, and triple combinations. Water-soluble tetrazolium-1 (WST-1) assay was used to investigate cell proliferation 24 h after treatments. Then, dose-response curves were plotted using WST-1outputs, and IC50 values were determined. For double and triple combinations respectively 0.5 × IC50 and 0.25 × IC50 were used. Data was analyzed with the software CompuSyn. Drug interactions were analyzed using Chou-Talalay method to calculate the combination index (CI).The data revealed that 17-AAG shows a potent synergistic interaction (CI < 1) with oxaliplatin and capecitabine in double combinations (0.5 × IC50) in both cell lines. In the case of triple combinations, the findings showed an antagonistic interaction (CI > 1) in HT-29 and a synergistic effect (CI < 1) in HCT-116 (0.25 × IC50) cell lines. It was concluded that double combinations of 17-AAG with oxaliplatin or capecitabine might be effective against HCT-116 and HT-29 cell lines. However, in triple combinations, positive results were seen only against HCT-116. Further investigation is suggested to confirm the effectiveness of these combinations in clinical trials.

Combined use of heat-shock protein 70 and glutamine synthetase is useful in the distinction of typical hepatocellular adenoma from atypical hepatocellular neoplasms and well-differentiated hepatocellular carcinoma

Well-differentiated hepatocellular carcinoma can mimic high-grade dysplastic nodule in cirrhotic liver and hepatocellular adenoma in non-cirrhotic liver. This study evaluates the efficacy of combined use of heat-shock protein 70 (HSP70), glutamine synthetase (GS) and glypican-3 in this setting. Immunohistochemistry for these three markers was done in 17 typical hepatocellular adenoma, 15 high-grade dysplastic nodules, 20 atypical hepatocellular neoplasms (14 clinically atypical and 6 pathologically atypical), 14 very well-differentiated hepatocellular carcinoma, and 43 well-differentiated hepatocellular carcinoma. All three markers were negative in typical adenomas. HSP70 was positive in 10, 71, and 67% of atypical neoplasms, very well-differentiated and well-differentiated HCC, respectively, while GS was positive in 60, 50, and 60% of atypical neoplasms, very well-differentiated and well-differentiated hepatocellular carcinoma, respectively. Glypican-3 was negative in all atypical neoplasms and very well-differentiated hepatocellular carcinoma, and was positive in 27% of well-differentiated hepatocellular carcinoma. Positive staining with at least one marker (HSP70 and/or GS) was seen in 85% of very well-differentiated hepatocellular carcinoma, which was similar to well-differentiated hepatocellular carcinoma (78%, P=0.4), and pathologically atypical cases (100%, P=0.5), but significantly higher compared with clinically atypical cases (43%. P=0.03) and none of typical adenomas (P<0.001). Positive staining with both GS and HSP70 was seen significantly more often in hepatocellular carcinoma compared with atypical neoplasms (45 vs 10%, P=0.004). Both these markers were also more often expressed in very well-differentiated hepatocellular carcinoma compared with atypical cases (38 vs 10%, P=0.06). In conclusion, the combined use of GS and HSP70 can be useful in the diagnosis of very well-differentiated hepatocellular carcinoma. These stains can also help in the distinction of typical adenoma from atypical hepatocellular neoplasms. Glypican-3 has low sensitivity and is not useful in this setting.

Tackling the emperor's wisdom: heat shock proteins to halt and reverse atrial fibrillation at its roots.

‘When the pulse is irregular and tremulous and the beats occur at intervals, then the impulse of life fades’. More than 4000 years ago, the Yellow Emperor of China wrote this in his classics of internal medicine (Huang Ti Nei Ching Su Wen) [1], perhaps thereby describing atrial fibrillation (AF) for the first time. Currently, AF is the most common sustained arrhythmia in Western society. Its prevalence of 1 % is expected to double in the next decades, primarily due to ageing of the population, making it a growing public health burden with an unacceptably high impact on quality of life. The pathophysiology of AF embeds a high mode of complexity, and the intermingling mechanisms underlying AF are still incompletely understood. In short, AF consists of heterogeneous electromechanical remodelling of the atria in a concealed phase, which is followed by presentation due to an initiating trigger. General modes of treatment focus on two main aspects: (1) termination of the initiating trigger, either by anti-arrhythmic medication, cardioversion, or ablation therapy, and (2) prevention of complications of AF, such as the formation of occluding thrombi or a high ventricular rate, which further exacerbates the pathophysiological consequences. However, curative treatment of the electromechanical remodelling, the main cause of AF development, maintenance, and progression, is currently not possible. The major problem for accurate and effective treatment of remodelling is the fact that at the moment of the first presentation of AF, the atria are already electrically and structurally remodelled to an advanced pathological level. As lessons from ancient history are still pertinent in today’s society, the saying of the Yellow Emperor is unfortunately still daily practice: AF patients have a doubled mortality risk. In the current issue of Netherlands Heart Journal, Lanters et al. [2] describe the outline of the just-started HALT&REVERSE project, which aims to stop and possibly even reverse the electromechanical remodelling that causes AF using heat shock proteins (HSPs). The HSPs form a family of cardioprotective proteins that are up-regulated during cellular stress and function as intracellular chaperones for other proteins. They were discovered in relation to heat shock stress (hence the name), but they are present during all kinds of stress, including atrial stress. Previous studies in patients showed that impaired HSP expression is associated with AF, and HSP induction in various animal models resulted in atrial electrophysiological changes and inhibition of AF [3]. The use of HSPs and their inducers in the HALT&REVERSE project is therefore a very interesting idea, which targets AF at its roots, potentially curing the pathological remodelled heart. The overall aim of the HALT&REVERSE project corresponds with an increasing mind-shift in cardiovascular research. Instead of only focusing on treatment of symptoms and complications, counteracting development of the underlying disease to be able to cure/limit/prevent the disease substrate, sometimes even before the onset of symptoms, is gaining more attention. In heart failure patients with an intraventricular conduction delay, for example, cardiac resynchronisation therapy (via intervention using electrical devices) is successfully used to reverse initial cardiac remodelling caused by altered activation [4]. Another illustrative example is a study by Asimaki et al. [5], investigating a genetic mutation in desmosomal proteins, which classically leads to arrhythmogenic cardiomyopathy (also known as arrhythmogenic right ventricular cardiomyopathy), a disease associated with a high incidence of sudden arrhythmogenic death. When cardiac remodelling was pharmacologically suppressed at an early stage, heart failure no longer developed, thereby treating the disease before its fatal onset. In this case, unravelling of the mechanism that initiates the cardiac remodelling, in combination with a sophisticated large drug-screening assay, opened doors for future curative therapy. Curative treatment of the remodelled substrate in AF will not only support the immediate (but often short-lasting) success that cardioversion or ablation therapy have, but it also has the potential to prevent and reverse AF development, maintenance, and progression on the longer term and thereby significantly reduce the AF burden for patients and society. Let’s hope that research on such curative therapeutics will finally add new ground-breaking milestones to medicine and become part of daily practice in AF treatment, so that the emperor’s wisdom, as expressed in his ancient documentations 4000 years ago, will truly become history.

Heat shock protein 70 overexpression does not attenuate atrophy in botulinum neurotoxin type A-treated skeletal muscle

Botulinum neurotoxin type A (BoNT/A) is used clinically to induce therapeutic chemical denervation of spastically contracted skeletal muscles. However, BoNT/A administration can also cause atrophy. We sought to determine whether a major proteolytic pathway contributing to atrophy in multiple models of muscle wasting, the ubiquitin proteasome system (UPS), is involved in BoNT/A-induced atrophy. Three and ten days following BoNT/A injection of rat hindlimb, soleus muscle fiber cross-sectional area was reduced 25 and 65%, respectively. The transcriptional activity of NF-κB and Foxo was significantly elevated at 3 days (2- to 4-fold) and 10 days (5- to 6-fold). Muscle RING-finger protein-1 (MuRF1) activity was elevated (2-fold) after 3 days but not 10 days, while atrogin-1 activity was not elevated at any time point. BoNT/A-induced polyubiquitination occurred after 3 days (3-fold increase) but was totally absent after 10 days. Proteasome activity was elevated (1.5- to 2-fold) after 3 and 10 days. We employed the use of heat shock protein 70 (Hsp70) to inhibit NF-κB and Foxo transcriptional activity. Electrotransfer of Hsp70 into rat soleus, before BoNT/A administration, was insufficient to attenuate atrophy. It was also insufficient to decrease BoNT/A-induced Foxo activity at 3 days, although NF-κB activity was abolished. By 10 days both NF-κB and Foxo activation were abolished by Hsp70. Hsp70-overexpression was unable to alter the levels of BoNT/A-induced effects on MuRF1/atrogin-1, polyubiquitination, or proteasome activity. In conclusion, Hsp70 overexpression is insufficient to attenuate BoNT/A-induced atrophy. It remains unclear what proteolytic mechanism/s are contributing to BoNT/A-induced atrophy, although a Foxo-MuRF1-ubiquitin-proteasome contribution may exist, at least in early BoNT/A-induced atrophy. Further clarification of UPS involvement in BoNT/A-induced atrophy is warranted.

Comparative Study of 17-AAG and NVP-AUY922 in Pancreatic and Colorectal Cancer Cells: Are There Common Determinants of Sensitivity?

The use of heat shock protein 90 (Hsp90) inhibitors is an attractive antineoplastic therapy. We wanted to compare the effects of the benzoquinone 17-allylamino-17-demethoxygeldanamycin (17-AAG, tanespimycin) and the novel isoxazole resorcinol–based Hsp90 inhibitor NVP-AUY922 in a panel of pancreatic and colorectal carcinoma cell lines and in colorectal primary cultures derived from tumors excised to patients. PANC-1, CFPAC-1, and Caco-2 cells were intrinsically resistant to 17-AAG but sensitive to NVP-AUY922. Other cellular models were sensitive to both inhibitors. Human epidermal growth factor receptor receptors and their downstream signaling pathways were downregulated in susceptible cellular models, and concurrently, Hsp70 was induced. Intrinsic resistance to 17-AAG did not correlate with expression of ATP-binding cassette transporters involved in multidrug resistance. Some 17-AAG-resistant, NVP-AUY922–sensitive cell lines lacked NAD(P)H:quinone oxidoreductase 1 (NQO1) enzyme and activity. However, colorectal LoVo cells still responded to both drugs in spite of having undetectable levels and activity of NQO1. Pharmacological and biologic inhibition of NQO1 did not confer resistance to 17-AAG in sensitive cell lines. Therefore, even though 17-AAG sensitivity is related to NQO1 protein levels and enzymatic activity, the absence of NQO1 does not necessarily convey resistance to 17-AAG in these cellular models. Moreover, NVP-AUY922 does not require NQO1 for its action and is a more potent inhibitor than 17-AAG in these cells. More importantly, we show in this report that NVP-AUY922 potentiates the inhibitory effects of chemotherapeutic agents, such as gemcitabine or oxaliplatin, and other drugs that are currently being evaluated in clinical trials as antitumor agents.

Tumor immunotherapy based on tumor-derived heat shock proteins (Review)

Heat shock proteins (HSPs), the most important type of molecular chaperone, are expressed in all eukaryotic cells and have multiple functions, including the folding and unfolding of other proteins and peptides, the transport of proteins and peptides and the support of antigen presentation processes. Due to these important properties, the use of HSPs has been explored as a promising tumor immunotherapy strategy. It has been previously demonstrated that HSP peptide complex (HSP.PC) derived from tumors is the immunogenic entity that elicits powerful antitumor immune responses. Previous animal studies and phase III clinical trials have demonstrated the efficacy, safety and feasibility of HSP-based tumor vaccines. However, the limitations are also apparent and specific alternatives have been developed. The present review focused on the history of HSP-based immunotherapy, the mechanism of its immunogenicity and the previous efforts to promote the efficacy. The current review may be useful for antitumor studies based on the tumor-derived HSPs.