Attenuated phosphorylation of heat shock protein 27 correlates with tumor progression in patients with hepatocellular carcinoma

FYN/TOPK/HSPB1 axis facilitates the proliferation and metastasis of gastric cancer

BACKGROUND

FYN is a nonreceptor tyrosine kinase that regulates diverse pathological processes. The pro-cancer role of FYN in multiple malignancies has been elucidated. However, the mechanisms that FYN promotes gastric cancer (GC) progression remain largely unknown.

METHODS

In vitro and in vivo assays were used to investigate the function of FYN. FYN, TOPK, p-TOPK expression in GC specimens were detected by immunohistochemistry. Phosphoproteomics assays identify TOPK downstream substrate molecules. The molecular mechanism was determined using COIP assays, pull-down assays, immunofluorescence co-localization assays, western blotting, ³²p-labeled isotope radioautography assays, vitro kinase assays, and TOPK knockout mice.

RESULTS

FYN was found to be significantly upregulated in GC tissues as well as in GC cells. Knockdown of FYN expression markedly attenuated the malignant phenotype of GC cells in vitro and in vivo. Mechanistically, we identified TOPK/PBK as a novel downstream substrate of FYN, FYN directly phosphorylates TOPK at Y272. One phosphospecific antibodies against Y272 was developed to validate the phosphorylation of TOPK by FYN. Moreover, the TOPK-272F mutation impaired the interaction between TOPK and FYN, leading to disappeared TOPK phosphorylation. Consistently, human GC tissues displayed increased p-TOPK(Y272), which correlated with poor survival. Phosphoproteomics results showed a significant downregulation of both HSPB1 and p-HSPB1(ser15) in TOPK-knockdown cells, which was confirmed by TOPK-konckout mice.

CONCLUSIONS

FYN directly binds to TOPK in GC cells and phosphorylates TOPK at the Y272, which leads to proliferation and metastasis of GC. FYN-TOPK axis facilitates GC progression by phosphorylating HSPB1. Collectively, our study elucidates the pivotal role of the FYN-TOPK-HSPB1 cascade in GC.

ZNF322A-mediated protein phosphorylation induces autophagosome formation through modulation of IRS1-AKT glucose uptake and HSP-elicited UPR in lung cancer

Background

ZNF322A is an oncogenic transcription factor that belongs to the Cys2His2-type zinc-finger protein family. Accumulating evidence suggests that ZNF322A may contribute to the tumorigenesis of lung cancer, however, the ZNF322A-mediated downstream signaling pathways remain unknown.

Methods

To uncover ZNF322A-mediated functional network, we applied phosphopeptide enrichment and isobaric labeling strategies with mass spectrometry-based proteomics using A549 lung cancer cells, and analyzed the differentially expressed proteins of phosphoproteomic and proteomic profiles to determine ZNF322A-modulated pathways.

Results

ZNF322A highlighted a previously unidentified insulin signaling, heat stress, and signal attenuation at the post-translational level. Consistently, protein-phosphoprotein-kinase interaction network analysis revealed phosphorylation of IRS1 and HSP27 were altered upon ZNF322A-silenced lung cancer cells. Thus, we further investigated the molecular regulation of ZNF322A, and found the inhibitory transcriptional regulation of ZNF322A on PIM3, which was able to phosphorylate IRS1 at serine¹¹⁰¹ in order to manipulate glucose uptake via the PI3K/AKT/mTOR signaling pathway. Moreover, ZNF322A also affects the unfolded protein response by phosphorylation of HSP27^S82 and eIF2a^S51, and triggers autophagosome formation in lung cancer cells.

Conclusions

These findings not only give new information about the molecular regulation of the cellular proteins through ZNF322A at the post-translational level, but also provides a resource for the study of lung cancer therapy.

Protective effect of dihydromyricetin on hyperthermia-induced apoptosis in human myelomonocytic lymphoma cells

Dihydromyricetin (DMY) is a traditional herbal medicine, with a wide range of biological activities. Extreme hyperthermia (HT) can suppress the immune system; thus, protection of the immune system is beneficial in heat-related diseases, including heatstroke. In our study, we revealed the protective effect of DMY against HT-induced apoptosis and analysed the underlying molecular mechanisms. We incubated human myelomonocytic lymphoma U937 cells at 44 °C for 30 min with or without DMY and followed by further incubation for 6 h at 37 °C. Cell viability was determined by the CCK-8 assay. DMY did not cause any cytotoxic effects in U937 cells even at high doses. HT treatment alone induced significant apoptosis, which was detected by DNA fragmentation and Annexin V/PI double staining. Mitochondrial dysfunction was identified by loss of mitochondrial membrane potential (MMP) during heat stimulation. Apoptotic related proteins were involved, truncated Bid and caspase-3 were upregulated, and Mcl-1 and XIAP were downregulated. We also identified the related signalling pathways, such as the MAPK and PI3K/AKT pathways. However, changes in HT were dramatically reversed when the cells were pretreated with DMY before exposure to HT. Overall, MAPKs and PI3K/AKT signalling, mitochondrial dysfunction, and caspase-mediated pathways were involved in the protective effect of DMY against HT-induced apoptosis in U937 cells, which was totally reversed by DMY pretreatment. These findings indicate a new clinical therapeutic strategy for the protection of immune cells during heatstroke.

Molecular Signaling Pathways and Therapeutic Targets in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a complex biological process and is often diagnosed at advanced stages with no effective treatment options. With advances in tumor biology and molecular genetic profiling, several different signaling pathways and molecular mechanisms have been identified as responsible for initiating and promoting HCC. Targeting these critical pathways, which include the receptor tyrosine kinase pathways, the Ras mitogen-activated protein kinase (Ras/Raf/MAPK), the phosphatidylinositol 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR), the Wnt/β-catenin signaling pathway, the ubiquitin/proteasome degradation and the hedgehog signaling pathway has led to the identification of novel therapeutics for HCC treatment. In this review, we elaborated on our current understanding of the signaling pathways involved in the development and initiation of HCC and anticipate the potential targets for therapeutic drug development.

The clinicopathological and prognostic value of HSP27 in hepatocellular carcinoma: a systematic review and meta-analysis

Background

In the recent past, there is increasing evidence demonstrating that HSP27 plays a key role in tumor progression. However, the relationship between HSP27 expression and the clinicopathological features of hepatocellular carcinoma (HCC), as well as its prognostic value in HCC patients remain controversial. Accordingly, we conducted a meta-analysis to assess the correlation between HSP27 expression and HCC, and determine the prognostic value of HSP27 in HCC.

Methods

The data included clinicopathological features and survival information extracted from the published literature in the databases PubMed, EMBASE, Cochrane Library, Web of Science, CNKI, and Wan Fang. The pooled odds ratios and hazard ratios with 95% CIs were calculated using Forest plot analysis.

Results

The meta-analysis results indicated that the positive HSP27 expression was significantly correlated with HCC incidence, tumor differentiation, and α-fetoprotein level in patients with HCC. However, the expression of HSP27 was not associated with metastasis, hepatitis B virus surface antigen, gender, tumor size, TNM stage, and vascular invasion. Additionally, HSP27 expression indicated a poor overall survival rate, but it was not related to disease-free survival rate.

Conclusion

This meta-analysis revealed that HSP27 may play a key role in the development of HCC and could be a reliable biomarker for the prognosis of patients with HCC. However, additional high-quality research is needed to support the results.

The significance of phosphorylated heat shock protein 27 on the prognosis of pancreatic cancer

Background and Aim

The precise role of phosphorylated heat shock protein (HSP) 27 (p-HSP27) in pancreatic cancer remains to be elucidated. The aim of this study was to investigate whether the expression of p-HSP27 predicts the prognosis of patients with pancreatic cancer.

Methods

We retrospectively assessed 49 biopsied pancreatic cancer tissue samples that were obtained prior to the treatment with gemcitabine. The correlations between p-HSP27 and the clinicopathological characteristics were analyzed.

Results

p-HSP27 was not correlated with the response to chemotherapy or histological type. However, the median survival time was significantly longer in the patients with high p-HSP27 (275 days, n = 18) than those with low p-HSP27 (205 days, n = 31) (P = 0.0158). A multivariate Cox proportional hazards regression analysis revealed that low p-HSP27 predicted a worse prognosis.

Conclusions

Higher p-HSP27 expression before chemotherapy was correlated with better survival, indicating that p-HSP27 expression could be used to predict the prognosis of pancreatic cancer.

Molecular pathogenesis of hepatocellular carcinoma and impact of therapeutic advances

Hepatocellular carcinoma (HCC) is a leading cause of cancer mortality and has an increasing incidence worldwide. HCC can be induced by multiple etiologies, is influenced by many risk factors, and has a complex pathogenesis. Furthermore, HCCs exhibit substantial heterogeneity, which compounds the difficulties in developing effective therapies against this highly lethal cancer. With advances in cancer biology and molecular and genetic profiling, a number of different mechanisms involved in the development and progression of HCC have been identified. Despite the advances in this area, the molecular pathogenesis of hepatocellular carcinoma is still not completely understood. This review aims to elaborate our current understanding of the most relevant genetic alterations and molecular pathways involved in the development and progression of HCC, and anticipate the potential impact of future advances on therapeutic drug development.

The Clinical Significance of Phosphorylated Heat Shock Protein 27 (HSPB1) in Pancreatic Cancer

Pancreatic cancer is one of most aggressive forms of cancer. After clinical detection it exhibits fast metastatic growth. Heat shock protein 27 (HSP27; HSPB1) has been characterized as a molecular chaperone which modifies the structures and functions of other proteins in cells when they are exposed to various stresses, such as chemotherapy. While the administration of gemcitabine, an anti-tumor drug, has been the standard treatment for patients with advanced pancreatic cancer, accumulating evidence shows that HSP27 plays a key role in the chemosensitivity to gemcitabine. In addition, phosphorylated HSP27 induced by gemcitabine has been associated with the inhibition of pancreatic cancer cell growth. In this review, we summarize the role of phosphorylated HSP27, as well as HSP27, in the regulation of chemosensitivity in pancreatic cancer.

Network-Based Analysis of Nutraceuticals in Human Hepatocellular Carcinomas Reveals Mechanisms of Chemopreventive Action

Chronic inflammation is associated with the development of human hepatocellular carcinoma (HCC), an essentially incurable cancer. Anti-inflammatory nutraceuticals have emerged as promising candidates against HCC, yet the mechanisms through which they influence the cell signaling machinery to impose phenotypic changes remain unresolved. Herein we implemented a systems biology approach in HCC cells, based on the integration of cytokine release and phospoproteomic data from high-throughput xMAP Luminex assays to elucidate the action mode of prominent nutraceuticals in terms of topology alterations of HCC-specific signaling networks. An optimization algorithm based on SigNetTrainer, an Integer Linear Programming formulation, was applied to construct networks linking signal transduction to cytokine secretion by combining prior knowledge of protein connectivity with proteomic data. Our analysis identified the most probable target phosphoproteins of interrogated compounds and predicted translational control as a new mechanism underlying their anticytokine action. Induced alterations corroborated with inhibition of HCC-driven angiogenesis and metastasis.

Maternal Smoking Dysregulates Protein Expression in Second Trimester Human Fetal Livers in a Sex-Specific Manner

CONTEXT

Maternal smoking during pregnancy has adverse effects on the offspring (eg, increased likelihood of metabolic syndrome and infertility), which may involve alterations in fetal liver function.

OBJECTIVE

Our aim was to analyze, for the first time, the human fetal liver proteome to identify pathways affected by maternal smoking.

DESIGN

Fetal liver proteins extracted from elective second trimester pregnancy terminations (12-16 weeks of gestation) were divided in four balanced groups based on sex and maternal smoking.

SETTING AND PARTICIPANTS

Livers were collected from 24 morphologically normal fetuses undergoing termination for nonmedical reasons and analyzed at the Universities of Aberdeen and Glasgow.

MAIN OUTCOME MEASURES

Protein extracts were resolved by 2D-PAGE and analyzed with SameSpots software. Ingenuity pathway analysis was used to investigate likely roles of dysregulated proteins identified by tandem liquid chromatography/mass spectroscopy.

RESULTS

Significant expression differences between one or more groups (fetal sex and/or maternal smoking) were found in 22 protein spots. Maternal smoking affected proteins with roles in post-translational protein processing and secretion (ERP29, PDIA3), stress responses and detoxification (HSP90AA1, HSBP1, ALDH7A1, CAT), and homeostasis (FTL1, ECHS1, GLUD1, AFP, SDHA). Although proteins involved in necrosis and cancer development were affected in both sexes, pathways affecting cellular homeostasis, inflammation, proliferation, and apoptosis were affected in males and pathways affecting glucose metabolism were affected in females.

CONCLUSIONS

The fetal liver exhibits marked sex differences at the protein level, and these are disturbed by maternal smoking. The foundations for smoke-induced post-natal diseases are likely to be due to sex-specific effects on diverse pathways.

Roles of p38α mitogen-activated protein kinase in mouse models of inflammatory diseases and cancer

The p38α mitogen‐activated protein kinase pathway not only regulates the production of inflammatory mediators, but also controls processes related to tissue homeostasis, such as cell proliferation, differentiation and survival, which are often disrupted during malignant transformation. The versatility of this signaling pathway allows for the regulation of many specific functions depending on the cell type and context. Here, we discuss mouse models that have been used to identify in vivo functions of p38α signaling in the pathogenesis of inflammatory diseases and cancer. Experiments using genetically modified mice and pharmacological inhibitors support that targeting the p38α pathway could be therapeutically useful for some inflammatory diseases and tumor types.

Heat shock protein 20 (HSPB6) regulates TNF-α-induced intracellular signaling pathway in human hepatocellular carcinoma cells

We previously demonstrated that the expression of HSP20, a small heat shock protein, is inversely correlated with the progression of HCC. Inflammation is associated with HCC, and numerous cytokines, including TNF-α, act as key mediators in the progression of HCC. In the present study, we investigated whether HSP20 is implicated in the TNF-α-stimulated intracellular signaling in HCC using human HCC-derived HuH7 cells in the presence of TNF-α. In HSP20-overexpressing HCC cells, the cell growth was retarded compared with that in the control cells under long-term exposure of TNF-α. Because NF-κB pathway is the main intracellular signaling system activated by TNF-α, we investigated the effects of HSP20-overexpression of this pathway. The protein levels of IKK-α, but not IKK-β, in the HSP20-overexpressing cells were decreased. Short-term exposure to TNF-α-induced phosphorylation and degradation of IκB, and the phosphorylation and transactivational activity of NF-κB were suppressed in the HSP20-overexpressing HCC cells. Furthermore, the increase in IKK-α levels was accompanied by a decrease in the HSP20 levels in human HCC tissues. These findings strongly suggest that HSP20 might decrease the IKK-α protein level and that it down-regulates the TNF-α-stimulated intracellular signaling in HCC, thus resulting in the suppression of HCC progression.

New insights in hepatocellular carcinoma: from bench to bedside

Hepatocarcinogenesis is a multistep process involving different genetic alterations that ultimately lead to malignant transformation of the hepatocyte. The liver is one of the main targets for different metastatic foci, but it represents an important and frequent locus of degeneration in the course of chronic disease. In fact, Hepatocellular carcinoma (HCC) represents the outcome of the natural history of chronic liver diseases, from the condition of fibrosis, to cirrhosis and finally to cancer. HCC is the sixth most common cancer in the world, some 630,000 new cases being diagnosed each year. Furthermore, about the 80% of people with HCC, have seen their clinical history developing from fibrosis, to cirrhosis and finally to cancer. The three main causes of HCC development are represented by HBV, HCV infection and alcoholism. Moreover, metabolic disease [starting from Non Alcoholic Fatty Liver Disease (NAFLD), Non Alcoholic Steatohepatitis (NASH)] and, with reduced frequency, some autoimmune disease may lead to HCC development. An additional rare cause of carcinogenetic degeneration of the liver, especially developed in African and Asian Countries, is represented by aflatoxin B1. The mechanisms by which these etiologic factors may induce HCC development involve a wide range of pathway and molecules, currently under investigation. In summary, the hepatocarcionogenesis results from a multifactorial process leading to the common condition of genetic changes in mature hepatocytes mainly characterized by uncontrolled proliferation and cell death. Advances in understanding the mechanism of action are fundamental for the development of new potential therapies and results primarily from the association of the research activities coming from basic and clinical science. This review article analyzes the current models used in basic research to investigate HCC activity, and the advances obtained from a basic and clinical point of view.

Heat shock response associated with hepatocarcinogenesis in a murine model of hereditary tyrosinemia type I

Hereditary Tyrosinemia type 1 (HT1) is a metabolic liver disease caused by genetic defects of fumarylacetoacetate hydrolase (FAH), an enzyme necessary to complete the breakdown of tyrosine. The severe hepatic dysfunction caused by the lack of this enzyme is prevented by the therapeutic use of NTBC (2-[2-nitro-4-(trifluoromethyl)benzoyl] cyclohexane-1,3-dione). However despite the treatment, chronic hepatopathy and development of hepatocellular carcinoma (HCC) are still observed in some HT1 patients. Growing evidence show the important role of heat shock proteins (HSPs) in many cellular processes and their involvement in pathological diseases including cancer. Their survival-promoting effect by modulation of the apoptotic machinery is often correlated with poor prognosis and resistance to therapy in a number of cancers. Here, we sought to gain insight into the pathophysiological mechanisms associated with liver dysfunction and tumor development in a murine model of HT1. Differential gene expression patterns in livers of mice under HT1 stress, induced by drug retrieval, have shown deregulation of stress and cell death resistance genes. Among them, genes coding for HSPB and HSPA members, and for anti-apoptotic BCL-2 related mitochondrial proteins were associated with the hepatocarcinogenetic process. Our data highlight the variation of stress pathways related to HT1 hepatocarcinogenesis suggesting the role of HSPs in rendering tyrosinemia-affected liver susceptible to the development of HCC.

Upregulation of phosphorylated HSP27, PRDX2, GRP75, GRP78 and GRP94 in acquired middle ear cholesteatoma growth

Cholesteatoma is a destructive and expanding growth of keratinizing squamous epithelium in the middle ear or petrous apex. The molecular and cellular processes of the pathogenesis of acquired middle ear cholesteatoma have not been fully understood. In this study, comparative proteomic analysis was conducted to investigate the roles of specific proteins in the pathways regarding keratinocyte proliferation in cholesteatoma. The differential proteins were detected by comparing the two-dimension electrophoresis (2-DE) maps of the epithelial tissues of 12 attic cholesteatomas with those of retroauricular skins. There were 14 upregulated proteins in the epithelial tissues of cholesteatoma in comparison with retroauricular skin. The modulation of five crucial proteins, HSP27, PRDX2, GRP75, GRP78 and GRP94, was further determined by RT-PCR, Western blot and immunohistochemistry. Phosphorylation of HSP27 at Ser-82 was identified by mass spectroscopy. The results of this study suggested that phosphorylated HSP27 is the end expression of two potential signal-transduction pathways, and together with PRDX2, they are very likely involved in the proliferation of keratinocytes in cholesteatoma. Upregulations of GRP75, GRP78 and GRP94 in keratinocytes may be able to counter endoplasmic reticulum stress, to inhibit cell apoptosis, to prevent protein unfolding and to promote cholesteatoma growth.

Hepatocellular carcinoma: a systems biology perspective

Hepatocellular carcinomas (HCCs) have different etiology and heterogenic genomic alterations lead to high complexity. The molecular features of HCC have largely been studied by gene expression and proteome profiling focusing on the correlations between the expression of specific markers and clinical data. Integration of the increasing amounts of data in databases has facilitated the link of genomic and proteomic profiles of HCC to disease state and clinical outcome. Despite the current knowledge, specific molecular markers remain to be identified and new strategies are required to establish novel-targeted therapies. In the last years, mathematical models reconstructing gene and protein networks based on experimental data of HCC have been developed providing powerful tools to predict candidate interactions and potential targets for therapy. Furthermore, the combination of dynamic and logical mathematical models with quantitative data allows detailed mechanistic insights into system properties. To address effects at the organ level, mathematical models reconstructing the three-dimensional organization of liver lobules were developed. In the future, integration of different modeling approaches capturing the effects at the cellular up to the organ level is required to address the complex properties of HCC and to enable the discovery of new targets for HCC prevention or treatment.

Cellular and molecular mechanisms of hepatocellular carcinoma: an update

Hepatocellular carcinoma (HCC) is the most common primary malignant tumor that accounts for ~80 % of all liver cancer cases worldwide. It is a multifactorial disease caused by a variety of risk factors and often develops in the background of underlying cirrhosis. A number of cellular phenomena, such as tumor microenvironment, inflammation, oxidative stress, and hypoxia act in concert with various molecular events to facilitate tumor initiation, progression, and metastasis. The emergence of microRNAs and molecular-targeted therapies adds a new dimension in our efforts to combat this deadly disease. Intense research in this multitude of areas has led to significant progress in our understanding of cellular processes and molecular mechanisms that occur during multistage events that lead to hepatocarcinogenesis. In this review, we discuss the current knowledge of HCC, focusing mainly on advances that have occurred during the past 5 years and on the development of novel therapeutics for liver cancer.

Phosphorylation status of heat shock protein 27 plays a key role in gemcitabine-induced apoptosis of pancreatic cancer cells

Gemcitabine, an antitumor drug, is currently considered to be the standard of care for the treatment of advanced pancreatic cancer, but the clinical outcome is still not satisfactory. Although heat shock protein (HSP) 27 is implicated in the resistance to chemotherapy in several types of cancers, the precise role of phosphorylated HSP27 in cancer cells remains to be clarified. In this study, we investigated the relationship between the effect of gemcitabine and the phosphorylation status of HSP27 in pancreatic cancer cells, Panc1 and KP3. Gemcitabine suppressed pancreatic cancer cell growth and induced apoptosis. Gemcitabine caused activation of p38 mitogen-activated protein kinase (MAPK), MAPK-activated protein kinase 2 (MAPKAPK-2) and subsequently phosphorylation of HSP27 at Ser15, 78 and 82 without affecting total HSP27 levels. The inhibitions of p38 MAPK and MAPKAPK-2 reduced the phosphorylation of HSP27 and apoptosis in gemcitabine-treated cells. To further investigate the role of phosphorylated HSP27, we established Panc1 cell lines which were stably transfected with empty vector (empty cells), wild-type HSP27-encoding vector (WT cells) and 2 mutant HSP27-encoding vectors that mimic non-phosphorylated (3A), and phosphorylated (3D), respectively. In comparison of empty cells with WT cells, there was no difference in cell growth rate and the sensitivity to gemcitabine. Interestingly, cell growth of 3D cells was retarded as compared to that of 3A cells. Taken together, our results strongly suggest that phosphorylation status of HSP27 plays a key role in gemcitabine-induced growth suppression of pancreatic cancer.

Therapeutics Based on microRNA: A New Approach for Liver Cancer

Hepatocellular carcinoma (HCC) is a serious public health hazard. Polygenes involvement, accumulation of genetic and epigenetic changes and immune response of viral vector during gene therapy have resulted in the high mortality rate without marked change. To provide a safeguard for gene therapy and the feasibility for a clinical application, efforts have been focused predominantly upon constructing liver-targeted vector recently. MicroRNAs (miRNAs), a class of short endogenous RNAs, regulate the gene expression at the post-transcriptional level through imperfect base pairing with the 3′-untranslated region of target mRNAs. miRNAs, especially the liver-specific miRNA: miR-122, have multiple functions in liver development and abnormal expression of miRNAs could lead to liver diseases. Altered miRNA expressions have been observed in HCCs, viral hepatitis and hepatic fibrosis. The different expression profiles of miRNAs in HCC suggest that miRNAs may serve as either novel potential targets acting directly as oncogenes or therapeutic molecules working as tumor suppressor genes. Moreover, the abundance in general and liver specificity in particular, all together make them attractive to be considered as elements for hepatic specific targeting viral vector. This review describes recent progress in miRNA investigation on liver associated for better understanding the relationship between miRNA and liver cancer in order to raise prospects for therapy.

Comparing signaling networks between normal and transformed hepatocytes using discrete logical models

Substantial effort in recent years has been devoted to constructing and analyzing large-scale gene and protein networks on the basis of "omic" data and literature mining. These interaction graphs provide valuable insight into the topologies of complex biological networks but are rarely context specific and cannot be used to predict the responses of cell signaling proteins to specific ligands or drugs. Conversely, traditional approaches to analyzing cell signaling are narrow in scope and cannot easily make use of network-level data. Here, we combine network analysis and functional experimentation by using a hybrid approach in which graphs are converted into simple mathematical models that can be trained against biochemical data. Specifically, we created Boolean logic models of immediate-early signaling in liver cells by training a literature-based prior knowledge network against biochemical data obtained from primary human hepatocytes and 4 hepatocellular carcinoma cell lines exposed to combinations of cytokines and small-molecule kinase inhibitors. Distinct families of models were recovered for each cell type, and these families clustered topologically into normal and diseased sets.

Regulation by heat shock protein 27 of osteocalcin synthesis in osteoblasts

We have previously reported that various stimuli, including sphingosine 1-phosphate, are able to induce heat shock protein (HSP) 27 in osteoblast-like MC3T3-E1 cells. However, the precise role of HSP27 in bone metabolism has not been satisfactory clarified. In this study, we investigated the effect of HSP27 on osteocalcin synthesis induced by bone morphogenetic protein (BMP)-4 or T₃ in these cells. In MC3T3-E1 cells, pretreatment with sphingosine 1-phosphate, sodium arsenite, or heat stress caused the attenuation of osteocalcin synthesis induced by BMP-4 or T₃ with concurrent HSP27 induction. To further investigate the effect of HSP27, we established stable HSP27-transfected cells. The osteocalcin synthesis was significantly reduced in the stable HSP27-transfected MC3T3-E1 cells and normal human osteoblasts compared with empty-vector transfected cells. On the other hand, anisomycin, a p38 MAPK activator, caused the phosphorylation of HSP27 in both sphingosine 1-phosphate-stimulated untransfected MC3T3-E1 cells and HSP27-transfected MC3T3-E1 cells. An immunofluorescence microscopy study showed that the phosphorylated HSP27 induced by anisomycin concentrated perinuclearly in these cells, in which it colocalized with the endoplasmic reticulum. We also established stable mutant-HSP27-transfected cells. Osteocalcin synthesis induced by either BMP-4 or T₃ was markedly suppressed in the nonphosphorylatable HSP27-overexpressing MC3T3-E1 cells compared with the phosphomimic HSP27-overexpressing cells. In contrast, the matrix mineralization was more obvious in nonphosphorylatable HSP27-overexpressing cells than that in phosphomimic HSP27-overexpressing cells. Taken together, these results strongly suggest that unphosphorylated HSP27 has an inhibitory effect on osteocalcin synthesis, but has a stimulatory effect on mineralization, in osteoblasts.

Epigenetic mechanisms involved in the pathogenesis of hepatobiliary malignancies

Primary tumors of the liver and biliary tree are increasing in frequency and portend a miserable prognosis. Epigenetic regulation of gene expression has emerged as a fundamental aspect of cancer development and progression. The molecular mechanisms of carcinogenesis in hepatocellular carcinoma and cholangiocarcinoma involve a complex interplay of both genetic and epigenetic factors. Recent studies investigating the possible epigenetic mechanisms induced in the disease have shed new light on the molecular underpinnings of hepatobiliary cancers. In addition, epigenetic modifications of DNA in cancer and precancerous lesions offer hope and the promise of novel biomarkers for early cancer detection, prediction, prognosis and response to treatment. Furthermore, the reversal of epigenetic changes represents a potential target for novel therapeutic strategies and medication design.

Heat shock protein 27 phosphorylation: kinases, phosphatases, functions and pathology

The small heat shock protein Hsp27 or its murine homologue Hsp25 acts as an ATP-independent chaperone in protein folding, but is also implicated in architecture of the cytoskeleton, cell migration, metabolism, cell survival, growth/differentiation, mRNA stabilization, and tumor progression. A variety of stimuli induce phosphorylation of serine residues 15, 78, and 82 in Hsp27 and serines 15 and 86 in Hsp25. This post-translational modification affects some of the cellular functions of Hsp25/27. As a consequence of the functional importance of Hsp25/27 phosphorylation, aberrant Hsp27 phosphorylation has been linked to several clinical conditions. This review focuses on the different Hsp25/27 kinases and phosphatases that regulate the phosphorylation pattern of Hsp25/27, and discusses the recent findings of the biological implications of these phosphorylation events in physiological and pathological processes. Novel therapeutic strategies aimed at restoring anomalous Hsp27 phosphorylation in human diseases will be presented.

PKA-induced F-actin rearrangement requires phosphorylation of Hsp27 by the MAPKAP kinase MK5

Mitogen-activated protein kinase (MAPK) pathways can play a role in F-actin dynamics. In particular, the p38 MAPK/MAPK-activated protein kinase 2 (MK2)/heat shock protein 27 (Hsp27) pathway is involved in F-actin alternations. Previously, we showed that MK5 is implicated in F-actin rearrangement induced by the cAMP/cAMP-dependent protein kinase pathway in PC12 cells, while others found Hsp27 to be a good in vitro MK5 substrate. Here we demonstrate that MK5 can specifically interact with Hsp27 in vivo and can induce phosphorylation at serine residues 78 and 82 in cells. siRNA-mediated depletion of Hsp27 protein levels, as well as overexpression of the non-phosphorylatable Hsp27-3A mutant prevented forskolin-induced F-actin reorganization. While ectopic expression of a constitutive active MK5 mutant was sufficient to induce F-actin rearrangement in PC12 cells, co-expression of Hsp27-3A could ablate this process. Our results imply that MK5 is involved in Hsp27-controlled F-actin dynamics in response to activation of the cAMP-dependent protein kinase pathway. These findings render the MK5/Hsp27 connection into a putative therapeutic target for conditions with aberrant Hsp27 phosphorylation such as metastasis, cardiovascular diseases, muscle atrophy, autoimmune skin disease and neuropathology.

Molecular mechanisms of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) typically has poor prognosis, because it is often diagnosed at an advanced stage. Heterogeneous phenotypic and genetic traits of affected individuals and a wide range of risk factors have classified it a complex disease. HCC is not amenable to standard chemotherapy and is resistant to radiotherapy. In most cases, surgical resection and liver transplantation remain the only curative treatment options. Therefore, development of novel, effective therapies is of prime importance. Extensive research over the past decade has identified a number of molecular biomarkers as well as cellular networks and signaling pathways affected in liver cancer. Recent studies using a combination of "omics" technologies, microRNA studies, combinatorial chemistry, and bioinformatics are providing new insights into the gene expression and protein profiles during various stages of the disease. In this review, we discuss the contribution of these newer approaches toward an understanding of molecular mechanisms of HCC and for the development of novel cancer therapeutics.

Hepatocyte necrosis induced by oxidative stress and IL-1 alpha release mediate carcinogen-induced compensatory proliferation and liver tumorigenesis

Hepatocyte I kappaB kinase beta (IKK beta) inhibits hepatocarcinogenesis by suppressing accumulation of reactive oxygen species (ROS) and liver damage, whereas JNK1 activation promotes ROS accumulation, liver damage, and carcinogenesis. We examined whether hepatocyte p38 alpha, found to inhibit liver carcinogenesis, acts similarly to IKK beta in control of ROS metabolism and cell death. Hepatocyte-specific p38 alpha ablation enhanced ROS accumulation and liver damage, which were prevented upon administration of an antioxidant. In addition to elevated ROS accumulation, hepatocyte death, augmented by loss of either IKK beta or p38 alpha, was associated with release of IL-1 alpha. Inhibition of IL-1 alpha action or ablation of its receptor inhibited carcinogen-induced compensatory proliferation and liver tumorigenesis. IL-1 alpha release by necrotic hepatocytes is therefore an important mediator of liver tumorigenesis.

Alpha2 adrenoreceptor agonist regulates protein kinase C-induced heat shock protein 27 phosphorylation in C6 glioma cells

Dexmedetomidine (Dexmd), a potent and highly specific alpha(2) adrenoreceptor agonist, is an efficient therapeutic agent for sedation. Dexmd has been recently reported to have a neuroprotective effect. Heat shock protein (HSP) 27, a low-molecular weight HSP has been shown to be expressed following cerebral ischemia in astrocytes but not in neurons. HSP27 expression is involved in ischemic tolerance of the brain. This study investigated the effect of Dexmd on HSP27 in rat C6 glioma cells. 12-O-tetradecanoylphorbol-13-actate (TPA), a direct activator of protein kinase C (PKC), stimulated the phosphorylation of HSP27 at Ser82, but not Ser15 in a time-dependent manner. Prostaglandin (PG) E(1) or PGE(2) which activates the adenylyl cyclase-cAMP system as well as forskolin and dibutyryl-cAMP, suppressed the TPA-induced phosphorylation of HSP27. Dexmd reversed the suppression of HSP27 phosphorylation by the adenylyl cyclase-cAMP system. Therefore, these results strongly suggest that Dexmd reverses the suppression of HSP27 phosphorylation by the adenylyl cyclase-cAMP system activation through the inhibition of its system in C6 cells. alpha(2) Adrenoreceptor agonists may therefore show a neuroprotective effect through the modification of HSP27 phosphorylation induced by PKC activation.

Responses of the 27-kDa heat shock protein to UVB irradiation in human epidermal melanocytes

Solar ultraviolet radiation (UVR) is a major environmental hazard for the skin, and UVB (280-320 nm) has been proposed to be a main factor for melanoma development. In response to sunlight exposure, the skin has adapted a number of innate resistance mechanisms. Among them is the small heat shock protein of 27 kDa (HSP27) known to play a role in the protection of cells from variety of environmental insults including UV irradiation. In this study, we demonstrated that UVB irradiation of cultured normal epidermal melanocytes initiates changes in HSP27 phosphorylation and localization. In unstressed melanocytes, HSP27 was present as the non-phosphorylated isoform. UVB irradiation with a physiological dose (7-25 mJ/cm(2)) resulted in the formation of a mono-phosphorylated isoform and sometimes a bi-phosphorylated isoform. The UVB-induced HSP27 phosphorylation was inhibited when melanocytes were treated with the antioxidant N-acetyl cysteine or inhibitor of p38 MAP kinase prior to UVB exposure, suggesting that UVB induced HSP27 phosphorylation through reactive oxygen species/p38 MAP kinase pathway. In response to UBV irradiation, HSP27 in melanocytes translocated from the cytoplasm to the nucleus. The HSP27 responses may provide some protective role against UVB-induced cell damage in the skin.

Oncoproteomics of hepatocellular carcinoma: from cancer markers' discovery to functional pathways

Hepatocellular carcinoma (HCC) is a heterogeneous cancer with no promising treatment and remains one of the most prevailing and lethal malignancies in the world. Researchers in many biological areas now routinely identify and characterize protein markers by a mass spectrometry-based proteomic approach, a method that has been commonly used to discover diagnostic biomarkers for cancer detection. The proteomic research platforms span from the classical two-dimensional polyacrylamide gel electrophoresis (2-DE) to the latest Protein Chip or array technology, which are often integrated with the MALDI (matrix-assisted laser-desorption ionization), SELDI (surface-enhanced laser desorption/ionization) or tandem mass spectrometry (MS/MS). New advances on quantitative proteomic analysis (e.g. SILAC, ICAT, and ITRAQ) and multidimensional protein identification technology (MudPIT) have greatly enhanced the capability of proteomic methods to study the expressions, modifications and functions of protein markers. The present article reviews the latest proteomic development and discovery of biomarkers in HCC that may provide insights into the underlying mechanisms of hepatocarcinogenesis and the readiness of biomarkers for clinical uses.

Phosphorylation of Ser78 of Hsp27 correlated with HER-2/neu status and lymph node positivity in breast cancer

Background

Abnormal amplification/expression of HER-2/neu oncogene has been causally linked with tumorigenesis and metastasis in breast cancer and associated with shortened overall survival of patients. Recently, heat shock protein 27 (Hsp27) was reported to be highly expressed in HER-2/neu positive tumors and cell lines. However, putative functional links between phosphorylation of Hsp27 with HER-2/neu status and other clinicopathological features remain to be elucidated.

Results

Comparative phosphoproteomic studies of HER-2/neu positive and -negative breast tumors revealed that Hsp27, one of the identified phosphoproteins, was highly phosphorylated in HER-2/neu positive tumors. The extent of Hsp27 phosphorylation at its Ser¹⁵, Ser⁷⁸ and Ser⁸² residues were further evaluated with site-specific antibodies in tumor samples by tissue lysate array- and tissue microarray-based analyses, and in the BT474 breast cancer cell line treated with heregulin α1 (HRG α1) or the p38 MAPK inhibitor, SB203580. The tissue lysate array study indicated that only the level of pSer⁷⁸ in HER-2/neu positive tumors was more than 2-fold that in HER-2/neu negative tumors. Treatment of BT474 cells with HRG α1 and SB203580 indicated that Ser⁷⁸ phosphorylation was mainly regulated by the HER-2/neu-p38 MAPK pathway. Immunohistochemical staining of sections from a tissue microarray with 97 breast tumors showed that positive staining of pSer⁷⁸ significantly correlated with HER-2/neu (p = 0.004) and lymph node positivity (p = 0.026).

Conclusion

This investigation demonstrated the significant correlation of enhanced phosphorylation of the Ser⁷⁸ residue of Hsp27 with HER-2/neu and lymph node positivity in breast cancer.

Protein kinase C delta regulates the phosphorylation of heat shock protein 27 in human hepatocellular carcinoma

We have recently reported that attenuated phosphorylation of heat shock protein (HSP) 27 correlates with tumor progression in patients with hepatocellular carcinoma (HCC). In the present study, we investigated what kind of kinase regulates phosphorylation of HSP27 in human HCC-derived HuH7 cells. 12-O-tetradecanoylphorbol-13-acetate (TPA) and 1-oleoyl-2-acetylglycerol, direct activators of protein kinase C (PKC), markedly strengthened the phosphorylation of HSP27. Bisindorylmaleimide I, an inhibitor of PKC, suppressed the TPA-induced levels of HSP27 phosphorylation in addition to its basal levels. Knock down of PKCdelta suppressed HSP27 phosphorylation, as well as p38 mitogen-activated protein kinase (MAPK) phosphorylation. SB203580, an inhibitor of p38 MAPK, suppressed the TPA-induced HSP27 phosphorylation. Our results strongly suggest that activation of PKCdelta regulates the phosphorylation of HSP27 via p38 MAPK in human HCC.

TNF-α decreases hsp 27 in human blood mononuclear cells: Involvement of protein kinase c

Treatment of PBMCs with TNF-alpha decreased the levels of heat shock protein (HSP) 27, but had little effect on the level of HSP70. Parallel to the decrease of HSP27, TNF-alpha increased the level of HSP27 in the incubation medium of the cells. The decrease of HSP27 induced by TNF-alpha was suppressed by the pretreatment of PBMCs with the specific protein kinase C (PKC) inhibitor, GF109203X. Furthermore, phorbol myristate acetate (PMA), a PKC stimulant, but not dibutyryl cyclic AMP, a protein kinase A stimulant, decreased the levels of HSP27. To investigate the effect of TNF-alpha on the oligomerization state of HSP27 in PBMCs, we performed sucrose density gradient centrifugation with subsequent fractionation and immunoassay. Extract of vehicle-treated PBMCs contained mainly dissociated forms of HSP27. The amounts of dissociated forms of HSP27 in PBMCs was decreased by TNF-alpha, while the amounts of aggregated form of HSP27 was little changed. In intact PBMCs, HSP27 is constitutively phosphorylated at Ser78, but not at Ser15 or at Ser82. The amount of phosphorylated HSP27 at Ser78 was decreased by TNF-alpha. These results indicate that TNF-alpha reduces HSP27 in PBMCs through PKC activation. This decrease may be due to efflux of dissociated form of HSP27, phosphorylated HSP27 at Ser78, from the cells.

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