Heat Shock Protein 27 Protects L929 Cells from Cisplatin-Induced Apoptosis by Enhancing Akt Activation and Abating Suppression of Thioredoxin Reductase Activity

Cellular landscaping of cisplatin resistance in cervical cancer

Cervical cancer (CC) caused by human papillomavirus (HPV) is one of the largest causes of malignancies in women worldwide. Cisplatin is one of the widely used drugs for the treatment of CC is rendered ineffective owing to drug resistance. This review highlights the cause of resistance and the mechanism of cisplatin resistance cells in CC to develop therapeutic ventures and strategies that could be utilized to overcome the aforementioned issue. These strategies would include the application of nanocarries, miRNA, CRIPSR/Cas system, and chemotherapeutics in synergy with cisplatin to not only overcome the issues of drug resistance but also enhance its anti-cancer efficiency. Moreover, we have also discussed the signaling network of cisplatin resistance cells in CC that would provide insights to develop therapeutic target sites and inhibitors. Furthermore, we have discussed the role of CC metabolism on cisplatin resistance cells and the physical and biological factors affecting the tumor microenvironments.

Activation of the HSP27-AKT axis contributes to gefitinib resistance in non-small cell lung cancer cells independent of EGFR mutations

PURPOSE

Although epidermal growth factor receptor (EGFR)-activating mutations in non-small cell lung cancer (NSCLC) usually show sensitivity to first-generation EGFR-tyrosine kinase inhibitors (TKIs), most patients relapse because of drug resistance. Heat shock protein 27 (HSP27) has been reported to be involved in the resistance of EGFR-TKIs, although the underlying mechanism is unclear. Here, we explore the mechanisms of HSP27-mediated EGFR TKI resistance and propose novel therapeutic strategies.

METHODS

To determine the mechanism of HSP27 associated gefitinib resistance, differences were assessed using gefitinib-sensitive and -resistant NSCLC cell lines. In vivo xenograft experiments were conducted to elucidate the combinatorial effects of J2, a small molecule HSP27 inhibitor, and gefitinib. Analyses of human NSCLC tissues and PDX tissues were also used for comparison of HSP27 and phosphorylated AKT expression.

RESULTS

Large-scale cohort analysis of NSCLC cases revealed that HSP27 expression correlated well with the incidence of EGFR mutations and affected patient survival. Increased pAKT and HSP27 was observed in gefitinib-resistant cells compared with gefitinib-sensitive cells. Moreover, increased phosphorylation of HSP27 by gefitinib augmented its protein stability and potentiated its binding activity with pAKT, which resulted in increased gefitinib resistance. However, in gefitinib-sensitive cells, stronger binding activity between EGFR and HSP27 was observed. Moreover, these phenomena occurred regardless of EGFR mutation including secondary mutations, such as T790M. AKT knockdown switched HSP27-pAKT binding to HSP27-EGFR, which promoted gefitinib sensitivity in gefitinib-resistant cells. Functional inhibition of HSP27 yielded sensitization to gefitinib in gefitinib-resistant cells by inhibiting the interaction between HSP27 and pAKT.

CONCLUSIONS

Our results indicate that combination of EGFR-TKIs with HSP27 inhibitors may represent a good strategy to overcome resistance to EGFR-TKIs, especially in cancers exhibiting AKT pathway activation.

Integral membrane protein 2A enhances sensitivity to chemotherapy via notch signaling pathway in cervical cancer

As the second most common cancer among women, cervical cancer is a huge threat to their health all over the world. Integral membrane protein 2A (ITM2A), a member of the Type II Integral Membrane protein (ITM2) family, has been reported to act as a tumor suppressor in breast cancer and ovarian cancer. Moreover, the low expression of ITM2A was associated with cervical adenocarcinoma. However, the function of ITM2A in drug resistance in cervical cancer remains unclear. Here, we used bioinformatics methods to screen differentially expressed genes (DEGs) closely related to chemotherapeutic relapse cervical carcinoma. ITM2A is downregulated in cervical tumor tissues and is associated with poor survival. Furthermore, ITM2A is also downregulated in cervical cancer cells with cisplatin resistance. Overexpression of ITM2A increases the cisplatin sensitivity of cervical cancer cells. Mechanically, ITM2A upregulation mediates the sensitivity of cervical cancer cell through Notch signaling pathway. Our study suggests that ITM2A may serve as a target in mediating cisplatin-resistant cervical cancer.

HSP27 role in cardioprotection by modulating chemotherapeutic doxorubicin-induced cell death

The common phenomenon expected from any anti-cancer drug in use is to kill the cancer cells without any side effects to non-malignant cells. Doxorubicin is an anthracycline derivative anti-cancer drug active over different types of cancers with anti-cancer activity but attributed to unintended cytotoxicity and genotoxicity triggering mitogenic signals inducing apoptosis. Administration of doxorubicin tends to both acute and chronic toxicity resulting in cardiomyopathy (left ventricular dysfunction) and congestive heart failure (CHF). Cardiotoxicity is prevented through administration of different cardioprotectants along with the drug. This review elaborates on mechanism of drug-mediated cardiotoxicity and attenuation principle by different cardioprotectants, with a focus on Hsp27 as cardioprotectant by prevention of drug-induced oxidative stress, cell survival pathways with suppression of intrinsic cell death. In conclusion, Hsp27 may offer an exciting/alternating cardioprotectant, with a wider study being need of the hour, specifically on primary cell line and animal models in conforming its cardioprotectant behaviour.

Cisplatin Resistance in Testicular Germ Cell Tumors: Current Challenges from Various Perspectives

Testicular germ cell tumors share a marked sensitivity to cisplatin, contributing to their overall good prognosis. However, a subset of patients develop resistance to platinum-based treatments, by still-elusive mechanisms, experiencing poor quality of life due to multiple (often ineffective) interventions and, eventually, dying from disease. Currently, there is a lack of defined treatment opportunities for these patients that tackle the mechanism(s) underlying the emergence of resistance. Herein, we aim to provide a multifaceted overview of cisplatin resistance in testicular germ cell tumors, from the clinical perspective, to the pathobiology (including mechanisms contributing to induction of the resistant phenotype), to experimental models available for studying this occurrence. We provide a systematic summary of pre-target, on-target, post-target, and off-target mechanisms putatively involved in cisplatin resistance, providing data from preclinical studies and from those attempting validation in clinical samples, including those exploring specific alterations as therapeutic targets, some of them included in ongoing clinical trials. We briefly discuss the specificities of resistance related to teratoma (differentiated) phenotype, including the phenomena of growing teratoma syndrome and development of somatic-type malignancy. Cisplatin resistance is most likely multifactorial, and a combination of therapeutic strategies will most likely produce the best clinical benefit.

Links between cancer metabolism and cisplatin resistance

Cisplatin is one of the most potent and widely used chemotherapeutic agent in the treatment of several solid tumors, despite the high toxicity and the frequent relapse of patients due to the onset of drug resistance. Resistance to chemotherapeutic agents, either intrinsic or acquired, is currently one of the major problems in oncology. Thus, understanding the biology of chemoresistance is fundamental in order to overcome this challenge and to improve the survival rate of patients. Studies over the last 30 decades have underlined how resistance is a multifactorial phenomenon not yet completely understood. Recently, tumor metabolism has gained a lot of interest in the context of chemoresistance; accumulating evidence suggests that the rearrangements of the principal metabolic pathways within cells, contributes to the sensitivity of tumor to the drug treatment. In this review, the principal metabolic alterations associated with cisplatin resistance are highlighted. Improving the knowledge of the influence of metabolism on cisplatin response is fundamental to identify new possible metabolic targets useful for combinatory treatments, in order to overcome cisplatin resistance.

Oleandrin synergizes with cisplatin in human osteosarcoma cells by enhancing cell apoptosis through activation of the p38 MAPK signaling pathway

Purpose

Our previous studies have reported the antitumor effect of oleandrin on osteosarcoma; however, its chemosensitizing effect in osteosarcoma treatment is still unknown. Therefore, we explored the sensitizing effects of oleandrin to cisplatin in osteosarcoma and investigated the potential mechanisms.

Methods

After exposure to oleandrin and/or cisplatin, CCK-8 and colony formation assays, DAPI staining and flow cytometry were performed to detect cell proliferation and apoptosis in 143B, U-2OS and MG-63 osteosarcoma cells. The median-effect analysis was applied to evaluate the combined effect. Western blot was used to determine the expression of related proteins. Osteosarcoma xenografts and histological observations were applied to confirm the combined effect in vivo.

Results

Compared with cisplatin or oleandrin alone, the combined treatment significantly inhibited cell proliferation and induced cell apoptosis. The median-effect analysis indicated a synergistic cytotoxic effect. The combined treatment downregulated Bcl-2 and upregulated Bax and cleaved caspase-3, -8 and -9. And the suppression of caspases reduced cell death. Furthermore, oleandrin alone or with cisplatin, activated the p38 MAPK/Elk-1 pathway. The inhibition of the p38 MAPK pathway increased cell viability and reduced apoptosis. In vivo, the combined treatment was also verified to significantly inhibit tumor growth, induce apoptosis and activate the p38 MAPK pathway.

Conclusions

The combination of oleandrin with cisplatin exerts a synergistic antitumor effect in osteosarcoma, which relates to the activation of the p38 MAPK pathway.

Multi-kinase inhibitors can associate with heat shock proteins through their NH2-termini by which they suppress chaperone function

We performed proteomic studies using the GRP78 chaperone-inhibitor drug AR-12 (OSU-03012) as bait. Multiple additional chaperone and chaperone-associated proteins were shown to interact with AR-12, including: GRP75, HSP75, BAG2; HSP27; ULK-1; and thioredoxin. AR-12 down-regulated in situ immuno-fluorescence detection of ATP binding chaperones using antibodies directed against the NH₂-termini of the proteins but only weakly reduced detection using antibodies directed against the central and COOH portions of the proteins. Traditional SDS-PAGE and western blotting assessment methods did not exhibit any alterations in chaperone detection. AR-12 altered the sub-cellular distribution of chaperone proteins, abolishing their punctate speckled patterning concomitant with changes in protein co-localization. AR-12 inhibited chaperone ATPase activity, which was enhanced by sildenafil; inhibited chaperone – chaperone and chaperone – client interactions; and docked in silico with the ATPase domains of HSP90 and of HSP70. AR-12 combined with sildenafil in a GRP78 plus HSP27 –dependent fashion to profoundly activate an eIF2α/ATF4/CHOP/Beclin1 pathway in parallel with inactivating mTOR and increasing ATG13 phosphorylation, collectively resulting in formation of punctate toxic autophagosomes. Over-expression of [GRP78 and HSP27] prevented: AR-12 –induced activation of ER stress signaling and maintained mTOR activity; AR-12 –mediated down-regulation of thioredoxin, MCL-1 and c-FLIP-s; and preserved tumor cell viability. Thus the inhibition of chaperone protein functions by AR-12 and by multi-kinase inhibitors very likely explains why these agents have anti-tumor effects in multiple genetically diverse tumor cell types.

The regulatory and signaling mechanisms of the ASK family

Apoptosis signal-regulating kinase 1 (ASK1) was identified as a MAP3K that activates the JNK and p38 pathways, and subsequent studies have reported ASK2 and ASK3 as members of the ASK family. The ASK family is activated by various intrinsic and extrinsic stresses, including oxidative stress, ER stress and osmotic stress. Numerous lines of evidence have revealed that members of the ASK family are critical for signal transduction systems to control a wide range of stress responses such as cell death, differentiation and cytokine induction. In this review, we focus on the precise signaling mechanisms of the ASK family in response to diverse stressors.

Molecular mechanisms of cisplatin resistance in cervical cancer

Patients with advanced or recurrent cervical cancer have poor prognosis, and their 1-year survival is only 10%–20%. Chemotherapy is considered as the standard treatment for patients with advanced or recurrent cervical cancer, and cisplatin appears to treat the disease effectively. However, resistance to cisplatin may develop, thus substantially compromising the efficacy of cisplatin to treat advanced or recurrent cervical cancer. In this article, we systematically review the recent literature and summarize the recent advances in our understanding of the molecular mechanisms underlying cisplatin resistance in cervical cancer.

Tumour-associated antigens and their anti-cancer applications

So far, a number of tumour-associated antigens (TAAs), such as heat shock proteins, alpha-fetoprotein, carcino-embryonic antigen and others have been identified in a variety of malignant tumours. Differences in the expression levels of TAAs in cancers compared with normal cells have led to these antigens being investigated as diagnostic and prognostic biomarkers or exciting targets in cancer treatment. Here, we systematically list the current representative TAAs to shed some light on current approaches and challenges for their anti-cancer application in cancer therapy. In this review, we discuss the ongoing pre-clinical studies and clinical development of TAAs in human cancers, and the potential application of these TAAs in the diagnosis and prognosis for cancer treatment.

Immune independent crosstalk between lymphoma and myeloid suppressor CD14+HLA-DRlow/neg monocytes mediates chemotherapy resistance

We have previously reported a novel phenotype of myeloid suppressors in lymphoma patients characterized by a loss of HLA-DR expression on monocytes, CD14⁺HLA-DR^low/neg. These cells were directly immunosuppressive and were associated with poor clinical outcome. In this study, we found that lymphoma tumors could have more than 30% of their tumor occupied by CD14⁺ cells. This intimate spatial connection suggested substantial cell–cell communication. We examined cross talk between monocytes from healthy volunteers (normal) and lymphoma cells in co-culture to identify the mechanisms and consequences of these interactions. Normal CD14⁺HLA-DR⁺ monocytes lost their HLA-DR expression after co-culture with lymphoma cells. Lymphoma-converted CD14⁺HLA-DR^low/neg cells exhibited similar immunosuppressive functions as CD14⁺HLA-DR^low/neg monocytes from lymphoma patients. Unexpectedly monocyte additions to lymphoma cell cultures protected lymphoma from cytotoxic killing by chemotherapy drug doxorubicin (DOX). Monocyte mediated resistance to DOX killing was associated with decreased Caspase-3 activity and increased anti-apoptotic heat shock protein-27 (Hsp27) expression. Soluble Hsp27 was detected in supernatant and patient plasma. Increased Hsp27 in plasma correlated with increased proportion of CD14⁺HLA-DR^low/neg monocytes in patient blood and was associated with lack of clinical response to DOX. This is the first report to describe a non-immune function of CD14⁺HLA-DR^low/neg monocytes: enhanced lymphoma resistance to chemotherapy. It is also the first report in lymphoma of Hsp27 as a potential mediator of lymphoma and monocyte crosstalk and chemotherapy resistance. Together with previous reports of the prevalence of these myeloid suppressors in other cancers, our findings identify this pathway and these interactions as a potential novel therapeutic target.

Systems biology of cisplatin resistance: past, present and future

The platinum derivative cis-diamminedichloroplatinum(II), best known as cisplatin, is currently employed for the clinical management of patients affected by testicular, ovarian, head and neck, colorectal, bladder and lung cancers. For a long time, the antineoplastic effects of cisplatin have been fully ascribed to its ability to generate unrepairable DNA lesions, hence inducing either a permanent proliferative arrest known as cellular senescence or the mitochondrial pathway of apoptosis. Accumulating evidence now suggests that the cytostatic and cytotoxic activity of cisplatin involves both a nuclear and a cytoplasmic component. Despite the unresolved issues regarding its mechanism of action, the administration of cisplatin is generally associated with high rates of clinical responses. However, in the vast majority of cases, malignant cells exposed to cisplatin activate a multipronged adaptive response that renders them less susceptible to the antiproliferative and cytotoxic effects of the drug, and eventually resume proliferation. Thus, a large fraction of cisplatin-treated patients is destined to experience therapeutic failure and tumor recurrence. Throughout the last four decades great efforts have been devoted to the characterization of the molecular mechanisms whereby neoplastic cells progressively lose their sensitivity to cisplatin. The advent of high-content and high-throughput screening technologies has accelerated the discovery of cell-intrinsic and cell-extrinsic pathways that may be targeted to prevent or reverse cisplatin resistance in cancer patients. Still, the multifactorial and redundant nature of this phenomenon poses a significant barrier against the identification of effective chemosensitization strategies. Here, we discuss recent systems biology studies aimed at deconvoluting the complex circuitries that underpin cisplatin resistance, and how their findings might drive the development of rational approaches to tackle this clinically relevant problem.

Ginkgo biloba extract decreases non-small cell lung cancer cell migration by downregulating metastasis-associated factor heat-shock protein 27

Heat-shock proteins (HSPs) are molecular chaperones that protect proteins from damage. HSP27 expression is associated with cancer transformation and invasion. Ginkgo biloba extract (EGb761), the most widely sold herbal supplement, has antiangiogenic effects and induces tumor apoptosis. Data regarding the effect of EGb761 on HSP expression is limited, particularly in cancer. HSP27 expression in paired tumors and normal lung tissues of 64 patients with non-small cell lung cancer (NSCLC) were detected by real-time PCR, western blotting, and immunohistochemistry. NSCLC cell lines (A549/H441) were used to examine the migratory abilities in vitro. NSCLC tissue showed higher HSP27 expression than normal lung tissue. Kaplan–Meier survival analysis showed that NSCLC patients with low HSP27 expression ratio (<1) had significantly longer survival time than those with a high expression ratio (>1) (p = 0.04). EGb761 inhibited HSP27 expression and migratory ability of A549/H441 cells, which is the same as HSP27-siRNA transfection effect. Moreover, EGb761 treatment activated the AKT and p38 pathways and did not affect the expression of PI3K, ERK, and JNK pathways. HSP27 is a poor prognostic indicator of NSCLC. EGb761 can decrease the migration ability of A549/H441 by inhibiting HSP27 expression most likely through AKT and p38 MAPK pathways activation.

HspB1, HspB5 and HspB4 in Human Cancers: Potent Oncogenic Role of Some of Their Client Proteins

Human small heat shock proteins are molecular chaperones that regulate fundamental cellular processes in normal unstressed cells as well as in many cancer cells where they are over-expressed. These proteins are characterized by cell physiology dependent changes in their oligomerization and phosphorylation status. These structural changes allow them to interact with many different client proteins that subsequently display modified activity and/or half-life. Nowdays, the protein interactomes of small Hsps are under intense investigations and will represent, when completed, key parameters to elaborate therapeutic strategies aimed at modulating the functions of these chaperones. Here, we have analyzed the potential pro-cancerous roles of several client proteins that have been described so far to interact with HspB1 (Hsp27) and its close members HspB5 (αB-crystallin) and HspB4 (αA-crystallin).

Expression of heat shock protein 27 and proliferating cell nuclear antigen in human retinoblastoma

AIM OF THE STUDY

This study aimed to observe the expressions of heat shock protein 27 (HSP27) and proliferating cell nuclear antigen (PCNA) in retinoblastoma (Rb) cells and to explore the relationships of the expression with Rb differentiation and optic nerve infiltration.

MATERIAL AND METHODS

Heat shock protein 27 and PCNA expressions in 36 routine Rb paraffin specimens were observed using PV9000 two-stage immunohistochemical staining. The correlations of the HSP27 and PCNA expressions with Rb differentiation and optic nerve infiltration were analyzed.

RESULTS

Heat shock protein 27 was weakly expressed in the normal retina, specifically in the ganglion cell layer. It was extensively expressed in Rb tissues at a positive rate of 69.4%, and the positive substances were primarily located in the cytoplasm. Proliferating cell nuclear antigen was expressed weakly or not at all expressed in the normal retina and was extensively expressed in Rb tissues at a positive rate of 83.3%, and the positive substances were primarily located in the nucleus. The positive expression rates of HSP27 and PCNA in the differentiated group were significantly higher than in the undifferentiated group (p < 0.05). The positive expression rates of HSP27 and PCNA in the optic nerve-infiltrated group were significantly higher than in the non-infiltrated group (p < 0.05). Heat shock protein 27 expression was positively correlated with PCNA expression in Rb (p < 0.01).

CONCLUSIONS

Heat shock protein 27 and PCNA expressions are markedly correlated with cell differentiation and optic nerve infiltration in Rb.

Proteomic identification of neoadjuvant chemotherapy-related proteins in bulky stage IB-IIA squamous cervical cancer

OBJECTIVE

The aim of this study was to investigate the effect of neoadjuvant chemotherapy (NAC) on the human squamous cervical cancer using proteomics profiling and to obtain related proteins to NAC exposure and response.

METHODS

Paired samples of early-stage bulky squamous cervical cancer before and after NAC treatment from patients who responded to NAC were obtained and submitted to 2-dimensional gel electrophoresis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MS). The expression and localization of the interesting proteins in additional paired samples were confirmed by Western blot analysis and immunohistochemistry.

RESULTS

The comparison of the proteins present before and after NAC revealed that 116 protein spots were significantly changed. In all, 31 proteins were analyzed by MS, and 15 proteins were upregulated in the cancer tissue after NAC relative to the level before NAC, whereas 16 proteins were downregulated after NAC. The significantly higher expression of peroxiredoxin 1 and significantly lower expression of galectin 1 after NAC treatment were confirmed by Western blot.

CONCLUSIONS

Proteomics can be used to identify the NAC-related proteins in squamous cervical cancer. The change in proteins may be associated with NAC exposure and response, but insight into their relevance requires further study.

Thioredoxin-mediated redox regulation of resistance to endocrine therapy in breast cancer

Resistance to endocrine therapy in breast carcinogenesis due to the redox regulation of the signal transduction system by reactive oxygen species (ROS) is the subject of this review article. Both antiestrogens and aromatase inhibitors are thought to prevent cancer through modulating the estrogen receptor function, but other mechanisms cannot be ruled out as these compounds also block metabolism and redox cycling of estrogen and are free radical scavengers. Endocrine therapeutic agents, such as, tamoxifen and other antiestrogens, and the aromatase inhibitor, exemestane, are capable of producing ROS. Aggressive breast cancer cells have high oxidative stress and chronic treatment with exemestane, fulvestrant or tamoxifen may add additional ROS stress. Breast cancer cells receiving long-term antiestrogen treatment appear to adapt to this increased persistent level of ROS. This, in turn, may lead to the disruption of reversible redox signaling that involves redox-sensitive phosphatases, protein kinases, such as, ERK and AKT, and transcription factors, such as, AP-1, NRF-1 and NF-κB. Thioredoxin modulates the expression of estrogen responsive genes through modulating the production of H2O2 in breast cancer cells. Overexpressing thioredoxine reductase 2 and reducing oxidized thioredoxin restores tamoxifen sensitivity to previously resistant breast cancer cells. In summary, it appears that resistance to endocrine therapy may be mediated, in part, by ROS-mediated dysregulation of both estrogen-dependent and estrogen-independent redox-sensitive signaling pathways. Further studies are needed to define the mechanism of action of thioredoxin modifiers, and their effect on the redox regulation that contributes to restoring the antiestrogen-mediated signal transduction system and growth inhibitory action.

A chemical proteomics approach reveals Hsp27 as a target for proapoptotic clerodane diterpenes

Clerodane diterpenoids are a class of naturally occurring molecules widely distributed in the Lamiaceae family. Neo-clerodane diterpenoids from Salvia ssp were recently described as compounds inhibiting the proliferation of human cancer cell lines. To gain new insights into molecular mechanism(s) underlying the antitumor potential of this class of compounds, we used a chemical proteomics approach to analyse the cellular interactome of hardwickiic acid (HAA) selected as a representative molecule. HAA was linked to an opportune 1,1'-carbonyldiimidazole modified by 1,12-dodecanediamine and then immobilized on a matrix support. The modified beads were then used as bait for fishing the potential partners of HAA in a U937 cell lysate. We identified heat shock protein 27 (Hsp27), an ATP-independent antiapoptotic chaperone characterized for its tumorigenic and metastatic properties and now referenced as a major therapeutic target in many types of cancer, as a major HAA partner. Here, we also report the study of HAA-Hsp27 interaction by means of a panel of chemical and biological approaches, including surface plasmon resonance measurements limited proteolysis, and biochemical assays. Our data suggest that HAA could provide a potential tool to develop strategies for the discovery of Hsp27 chemical inhibitors.

Critical role of heat shock protein 27 in bufalin-induced apoptosis in human osteosarcomas: a proteomic-based research

Bufalin is the primary component of the traditional Chinese herb "Chan Su". Evidence suggests that this compound possesses potent anti-tumor activities, although the exact molecular mechanism(s) is unknown. Our previous study showed that bufalin inhibited growth of human osteosarcoma cell lines U2OS and U2OS/MTX300 in culture. Therefore, this study aims to further clarify the in vitro and in vivo anti-osteosarcoma effects of bufalin and its molecular mechanism of action. We found bufalin inhibited both methotrexate (MTX) sensitive and resistant human osteosarcoma cell growth and induced G2/M arrest and apoptosis. Using a comparative proteomics approach, 24 differentially expressed proteins following bufalin treatment were identified. In particular, the level of an anti-apoptotic protein, heat shock protein 27 (Hsp27), decreased remarkably. The down-regulation of Hsp27 and alterations of its partner signaling molecules (the decrease in p-Akt, nuclear NF-κB p65, and co-immunoprecipitated cytochrome c/Hsp27) were validated. Hsp27 over-expression protected against bufalin-induced apoptosis, reversed the dephosphorylation of Akt and preserved the level of nuclear NF-κB p65 and co-immunoprecipitated Hsp27/cytochrome c. Moreover, bufalin inhibited MTX-resistant osteosarcoma xenograft growth, and a down-regulation of Hsp27 in vivo was observed. Taken together, bufalin exerted potent anti-osteosarcoma effects in vitro and in vivo, even in MTX resistant osteosarcoma cells. The down-regulation of Hsp27 played a critical role in bufalin-induced apoptosis in osteosarcoma cells. Bufalin may have merit to be a potential chemotherapeutic agent for osteosarcoma, particularly in MTX-resistant groups.

Triptolide cooperates with Cisplatin to induce apoptosis in gemcitabine-resistant pancreatic cancer

OBJECTIVES

We aim to pharmacologically downregulate heat shock protein 27 (HSP27) through triptolide (TPL) to improve the drug sensitivity of pancreatic cancer to cisplatin (DDP).

METHODS

In vitro, we assessed cell viability and apoptosis by the combination of TPL and DDP in gemcitabine-resistant human pancreatic carcinoma PANC-1 and MIA PaCa-2 cell lines and examined the effect of silencing HSP27 by a small interfering RNA on cytotoxicity induced by TPL or DDP. In vivo, we apply TPL with DDP in a xenograft model to test the synergic action.

RESULTS

Triptolide cooperates with DDP to decrease cell viability and to induce apoptosis via the mitochondrial pathway, which is accompanied by a sharp decline in HSP27. Knocking down endogenous HSP27 can sensitize cancer cells to cytotoxicity with TPL or DDP, indicating the critical role of HSP27 down-regulation in the synergic effect. Meanwhile, TPL acts in synergy with DDP to cause tumor regression in vivo.

CONCLUSIONS

The combined therapy of TPL and DDP triggers a synergic apoptosis via inhibiting HSP27 in human gemcitabine-resistant pancreatic carcinoma and has a strong potential to be developed into a new effective regimen for pancreatic cancer treatment.

Targeting heat shock protein 27 (HspB1) interferes with bone metastasis and tumour formation in vivo

Background:

The small stress heat shock protein 27 (Hsp27) has recently turned as a promising target for cancer treatment. Hsp27 upregulation is associated with tumour growth and resistance to chemo- and radio-therapeutic treatments, and several ongoing drugs inhibiting Hsp27 expression are under clinical trial. Hsp27 is now well described to counteract apoptosis and its elevated expression is associated with increased aggressiveness of several primary tumours. However, its role in the later stage of tumour progression and, more specifically, in the later and most deadly stage of tumour metastasis is still unclear.

Methods/results:

In the present study, we showed by qRT–PCR that Hsp27 gene is overexpressed in a large fraction of the metastatic breast cancer area in 53 patients. We further analysed the role of this protein in mice during bone metastasis invasion and establishment by using Hsp27 genetically depleted MDA-MB231/B02 human breast cancer cell line as a model. We demonstrate that Hsp27 silencing led to reduced cell migration and invasion in vitro and that in vivo it correlated with a decreased ability of breast cancer cells to metastasise and grow in the skeleton.

Conclusion:

Altogether, these data characterised Hsp27 as a potent therapeutic target in breast cancer bone metastasis and skeletal tumour growth.

Knock down of heat shock protein 27 (HspB1) induces degradation of several putative client proteins

Hsp27 belongs to the heat shock protein family and displays chaperone properties in stress conditions by holding unfolded polypeptides, hence avoiding their inclination to aggregate. Hsp27 is often referenced as an anti-cancer therapeutic target, but apart from its well-described ability to interfere with different stresses and apoptotic processes, its role in non-stressed conditions is still not well defined. In the present study we report that three polypeptides (histone deacetylase HDAC6, transcription factor STAT2 and procaspase-3) were degraded in human cancerous cells displaying genetically decreased levels of Hsp27. In addition, these proteins interacted with Hsp27 complexes of different native size. Altogether, these findings suggest that HDAC6, STAT2 and procaspase-3 are client proteins of Hsp27. Hence, in non stressed cancerous cells, the structural organization of Hsp27 appears to be a key parameter in the regulation by this chaperone of the level of specific polypeptides through client-chaperone type of interactions.

Newcastle disease virus induces apoptosis in cisplatin-resistant human lung adenocarcinoma A549 cells in vitro and in vivo

Cisplatin (DDP) is widely used in lung cancer chemotherapy. However, cisplatin resistance represents a major obstacle in effective clinical treatment. This study aims to investigate whether Newcastle disease virus (NDV) exhibits an oncolytic effect on cisplatin-resistant A549 lung cancer cells. We found that NDV induced A549/DDP cell apoptosis via the caspase pathway, particularly involving caspase-9, while the mitogen-activated protein kinase (MAPK) and Akt pathways also contributed to apoptotic induction. Furthermore, NDV displayed oncolytic effects in a mouse A549/DDP lung cancer model. Collectively, our data indicate that NDV could overcome the cisplatin resistance in lung cancer cells in vitro and in vivo.

Akt is the downstream target of GRP78 in mediating cisplatin resistance in ER stress-tolerant human lung cancer cells

Cisplatin [cis-diaminodichloroplatinum (II) (CDDP)] is the cornerstone of lung cancer chemotherapy. However, its efficacy is limited due to the development of drug resistance in cancer cells. This study was designed to uncover the mechanisms under CDDP resistance in lung cancer cells involving endoplasmic reticulum (ER) stress tolerance-induced and GRP78-dependant Akt activation. In this study we established ER stress-tolerant (ERST) human lung cancer lines H460et and A549et. We found that the ERST Lung cancer cells are resistant to CDDP treatment. We further showed that, compared to the parental cell lines, H460et and A549et show significantly increased GRP78 and phospho(p)-Akt levels. And phosphorylation of Akt, which can be regulated by GRP78, is essential to the ERST-associated CDDP resistance. Our findings identify a new mechanism of regulating Akt activity and a new mechanism through which CDDP resistance is formed in lung cancer cells.

Molecular mechanisms of cisplatin resistance

Platinum-based drugs, and in particular cis-diamminedichloroplatinum(II) (best known as cisplatin), are employed for the treatment of a wide array of solid malignancies, including testicular, ovarian, head and neck, colorectal, bladder and lung cancers. Cisplatin exerts anticancer effects via multiple mechanisms, yet its most prominent (and best understood) mode of action involves the generation of DNA lesions followed by the activation of the DNA damage response and the induction of mitochondrial apoptosis. Despite a consistent rate of initial responses, cisplatin treatment often results in the development of chemoresistance, leading to therapeutic failure. An intense research has been conducted during the past 30 years and several mechanisms that account for the cisplatin-resistant phenotype of tumor cells have been described. Here, we provide a systematic discussion of these mechanism by classifying them in alterations (1) that involve steps preceding the binding of cisplatin to DNA (pre-target resistance), (2) that directly relate to DNA-cisplatin adducts (on-target resistance), (3) concerning the lethal signaling pathway(s) elicited by cisplatin-mediated DNA damage (post-target resistance) and (4) affecting molecular circuitries that do not present obvious links with cisplatin-elicited signals (off-target resistance). As in some clinical settings cisplatin constitutes the major therapeutic option, the development of chemosensitization strategies constitute a goal with important clinical implications.

Inhibition of heat shock protein 27 (HspB1) tumorigenic functions by peptide aptamers

Human heat shock protein 27 (Hsp27, HspB1) is an anti-apoptotic protein characterized for its tumorigenic and metastatic properties, and now referenced as a major therapeutic target in many types of cancer. Hsp27 biochemical properties rely on a structural oligomeric and dynamic organization. Downregulation by small interfering RNA or inhibition with dominant-negative mutant have proven their efficiency to counteract the anti-apoptotic and protective properties of Hsp27. In this study, we report the isolation and characterization of Hsp27-targeted molecules interfering with its structural organization. Using the peptide aptamer (PA) strategy, we isolated PAs that specifically interact with Hsp27 and not with the other members of the small heat shock protein family. In mammalian cell cultures, PAs expression perturbed the dimerization and oligomerization of Hsp27, and acted as negative regulators of the anti-apoptotic and cytoprotective activities of this protein. Further studies analyzing SQ20B cell xenografts in immunocompromised mice showed that PAs strongly reduced tumor development through cell cycle arrest. Our data suggest that PAs could provide a potential tool to develop strategies for the discovery of Hsp27 chemical inhibitors.

Hsp27 protects adenocarcinoma cells from UV-induced apoptosis by Akt and p21-dependent pathways of survival

Transcriptional activation of p53 target genes, due to DNA damage, causes either apoptosis or survival by cell cycle arrest and DNA repair. However, the regulators of the choice between cell death and survival signaling have not been completely elucidated. Here, we report that human adenocarcinoma cells (MCF-7) survive UV-induced DNA damage by heat shock protein 27 (Hsp27)-assisted Akt/p21 phosphorylation/translocation. Protein levels of the p53 target genes, such as p21, Bcl-2, p38MAPK, and Akt, showed a positive correlation to Hsp27 level during 48 hours postirradiation, whereas p53 expression increased initially but started decreasing after 12 hours. Hsp27 prevented the G(1)-S phase cell cycle arrest, observed after 8 hours of post-UV irradiation, and PARP-1 cleavage was inhibited. Conversely, silencing Hsp27 enhanced G(1)-S arrest and cell death. Moreover, use of either Hsp27 or Akt small interference RNA reduced p21 phosphorylation and enhanced its retention in nuclei even after 48 hours postirradiation, resulting in enhanced cell death. Our results showed that Hsp27 expression and its direct chaperoning interaction increases Akt stability, and p21 phosphorylation and nuclear-to-cytoplasm translocation, both essential effects for the survival of UV-induced DNA-damaged cells. We conclude that the role of Hsp27 in cancer is not only for enhanced p53 proteolysis per se, rather it is also a critical determinant in p21 phosphorylation and translocation.

Over-expression of ERp29 attenuates doxorubicin-induced cell apoptosis through up-regulation of Hsp27 in breast cancer cells

The endoplasmic reticulum protein 29 (ERp29) has a critical role in regulating protein folding, maturation and secretion. However, its role in carcinogenesis remains elusive. Recently, we reported that ERp29 is a novel tumor suppressor and regulates mesenchymal-epithelial transition in MDA-MB-231 breast cancer cells. Here, we investigated whether ERp29 plays a role in the response of breast cancer cells to chemotherapeutic agents. We found that expression of ERp29 increased the resistance to doxorubicin, but not cisplatin and paclitaxel, and decreased the doxorubicin-induced cell apoptosis in MDA-MB-231 cells, whereas knockdown of ERp29 in MCF-7 cells increased the doxorubicin cytotoxicity. A proteomics study identified up-regulation of Hsp27 and down-regulation of stathmin-1, galectin and prohibitin in the doxorubicin-resistant, ERp29 over-expressing MDA-MB-231 cells. Further, we demonstrated that ERp29 up-regulated expression of Hsp27 by down-regulating eukaryotic translational initiation factor 2α (eIF2α). When Hsp27 was knocked down by siRNA in the doxorubicin-resistant, ERp29 over-expressing MDA-MB-231 cells and parental MCF-7 cells, cell viability was significantly decreased and doxorubicin-induced cell apoptosis was enhanced. These results indicate that Hsp27 is involved in the ERp29-mediated resistance to doxorubicin. Therefore, targeting of Hsp27, with a combination of other chemotherapeutic agents, is a rational strategy in treating doxorubicin-resistant cancer cells.

Cellular responses to Cisplatin-induced DNA damage

Cisplatin is one of the most effective anticancer agents widely used in the treatment of solid tumors. It is generally considered as a cytotoxic drug which kills cancer cells by damaging DNA and inhibiting DNA synthesis. How cells respond to cisplatin-induced DNA damage plays a critical role in deciding cisplatin sensitivity. Cisplatin-induced DNA damage activates various signaling pathways to prevent or promote cell death. This paper summarizes our current understandings regarding the mechanisms by which cisplatin induces cell death and the bases of cisplatin resistance. We have discussed various steps, including the entry of cisplatin inside cells, DNA repair, drug detoxification, DNA damage response, and regulation of cisplatin-induced apoptosis by protein kinases. An understanding of how various signaling pathways regulate cisplatin-induced cell death should aid in the development of more effective therapeutic strategies for the treatment of cancer.

Heat shock proteins: cellular and molecular mechanisms in the central nervous system

Emerging evidence indicates that heat shock proteins (HSPs) are critical regulators in normal neural physiological function as well as in cell stress responses. The functions of HSPs represent an enormous and diverse range of cellular activities, far beyond the originally identified roles in protein folding and chaperoning. HSPs are now understood to be involved in processes such as synaptic transmission, autophagy, ER stress response, protein kinase and cell death signaling. In addition, manipulation of HSPs has robust effects on the fate of cells in neurological injury and disease states. The ongoing exploration of multiple HSP superfamilies has underscored the pluripotent nature of HSPs in the cellular context, and has demanded the recent revamping of the nomenclature referring to these families to reflect a re-organization based on structure and function. In keeping with this re-organization, we first discuss the HSP superfamilies in terms of protein structure, regulation, expression and distribution in the brain. We then explore major cellular functions of HSPs that are relevant to neural physiological states, and from there we discuss known and proposed HSP impacts on major neurological disease states. This review article presents a three-part discussion on the array of HSP families relevant to neuronal tissue, their cellular functions, and the exploration of therapeutic targets of these proteins in the context of neurological diseases.

Functional promoter -1271G>C variant of HSPB1 predicts lung cancer risk and survival

PURPOSE Heat-shock protein 27 (Hsp27), encoded by HSPB1, plays crucial roles in tumorigenesis and cell survival and is reported to be an independent prognosis marker for cancer. We hypothesized that genetic variants of the HSPB1 gene may be associated with lung cancer susceptibility and survival. PATIENTS AND METHODS We first resequenced the full-length HSPB1 gene and then genotyped three selected tag single nucleotide polymorphisms (SNPs) in 1,152 paired Chinese lung cancer patient cases and controls. Another 500 paired patient cases and controls were used for replication. We also evaluated the roles of these tagSNPs in the overall survival of 248 patients with advanced non-small-cell lung cancer (NSCLC), and validated the results in another 335 patients with advanced NSCLC. The genotype-phenotype correlation was assessed in 309 workers with occupational exposure to polycyclic-aromatic hydrocarbons (PAHs) as well as by luciferase reporter assay and Western blotting analysis. RESULTS The -1271C allele was associated with a significantly increased lung cancer risk in the two independent patient case-control studies (P < .05 for both), but it conferred a favorable survival for patients with advanced NSCLC in two independent cohorts (adjusted hazard ratio, 0.66 and 0.75, respectively). The occupational PAH-exposed workers carrying the -1271C allele showed higher DNA damage levels than those with the -1271G allele (P = .027). Furthermore, the -1271C allele significantly decreased luciferase activity in four cell lines and resulted in lower Hsp27 expression levels in normal lung tissues when compared with -1271G allele (P < .05). CONCLUSION The functional HSPB1 promoter -1271G>C variant may affect lung cancer susceptibility and survival by modulating endogenous Hsp27 synthesis levels.

HSP27: mechanisms of cellular protection against neuronal injury

The heat shock protein (HSP) family has long been associated with a generalized cellular stress response, particularly in terms of recognizing and chaperoning misfolded proteins. While HSPs in general appear to be protective, HSP27 has recently emerged as a particularly potent neuroprotectant in a number of diverse neurological disorders, ranging from ALS to stroke. Although its robust protective effect on a number of insults has been recognized, the mechanisms and regulation of HSP27's protective actions are still undergoing intense investigation. On the basis of recent studies, HSP27 appears to have a dynamic and diverse range of function in cellular survival. This review provides a forum to compare and contrast recent literature exploring the protective mechanism and regulation of HSP27, focusing on neurological disorders in particular, as they represent a range from protein aggregate-associated diseases to acute stress.

Intravesical combination treatment with antisense oligonucleotides targeting heat shock protein-27 and HTI-286 as a novel strategy for high-grade bladder cancer

Clinical results of current intravesical chemotherapeutics are insufficient, and novel and safe intravesical options for high-risk bladder cancer are required to prevent both recurrence and progression. In this study, we show promising efficacy of intravesical combination treatment using antisense oligonucleotides targeting heat shock protein-27 (Hsp27; OGX427) with HTI-286, a synthetic analogue of the marine sponge product hemiasterlin. The expression of Hsp27 in bladder cancer was examined using tissue microarray analysis. Then, four bladder cancer cell lines were screened for combination effects of OGX427 with HTI-286, and the molecular mechanisms underlying the synergic effect were analyzed. Chemosensitivity against HTI-286 was also compared between mock-transfected T24 (T24 mock) cells and Hsp27-overexpressing T24 (T24 Hsp27) cells. Furthermore, in vivo data were obtained in a bioluminescent orthotopic murine model of high-grade disease. Hsp27 is expressed at higher levels in bladder cancers compared with normal bladder epithelium. OGX427 significantly enhanced cytotoxicity of HTI-286. Combination treatment induced Akt inactivation and Bcl-2 down-regulation. T24 Hsp27 cells were more resistant to HTI-286 than T24 mock cells and showed stronger Akt activation after HTI-286 treatment. The protective effect of Hsp27 against HTI-286 was suppressed by LY294002, a phosphatidylinositol 3-kinase inhibitor, indicating that Hsp27-Akt interactions are key mechanisms to enhance chemosensitivity via OGX427. Intravesical combination therapy effectively inhibited orthotopic tumor growth without toxic side effects. Our results suggest that OGX427 enhances cytotoxicity of HTI-286 through Akt inactivation and provide strong preclinical proof-of-principle for intravesical administration of OGX427 in combination with HTI-286 for high-grade bladder cancer.

Heat shock protein 27 as a new therapeutic target for radiation sensitization of head and neck squamous cell carcinoma

In a wide range of human cancers, increased levels of heat shock protein 27 (Hsp27) are closely associated with tumorigenesis, metastasis, resistance to anticancer therapeutics, and thus poor prognosis. In this study, we evaluate the radiosensitizing effects of Hsp27 gene silencing using OGX-427, a second-generation antisense oligonucleotide (ASO), on the radioresistant head and neck squamous cell carcinoma (HNSCC) SQ20B cells. In vitro, the downregulation of Hsp27 significantly enhanced radiation-induced apoptotic and clonogenic death, and promoted Akt inactivation. In vivo, combining OGX-427 with local tumor irradiation (5 x 2 Gy) led to a significant regression of SQ20B tumors related to a high rate of apoptosis and decreased levels of glutathione antioxidant defenses. Increasing the total radiation dose (15 x 2 Gy) significantly amplified the radiosensitizing effect of OGX-427. Treatment of tumors with OGX-427 plus radiation resulted in a decrease in angiogenesis associated with a reduced activation of the Akt pathway. Furthermore, the combined treatment enhanced the survival of SQ20B-bearing mice and showed no signs of acute and delayed toxicity. Our findings demonstrate for the first time that Hsp27 knockdown enhances the cytotoxic effects of radiotherapy in vivo and provide preclinical proof of principle for clinical trials using Hsp27 antisense technology in the treatment of patients with HNSCC radioresistant cancers.

Expression of heat shock protein 27 and alpha-crystallins in human retinoblastoma after chemoreduction

AIM

Small heat shock proteins (sHSP) play an important role in the resistance to anticancer drugs. We examined the expression of the sHSP family, HSP27 and alpha-crystallins, in human retinoblastoma with and without preoperative chemotherapy.

METHODS

Eighteen enucleated eyes from patients with retinoblastoma were used. Six patients had undergone chemotherapy before enucleation. Formalin-fixed, paraffin-embedded tissue sections were processed for H&E staining and examined by immunohistochemistry using anti-HSP27 and alpha-crystallins antibodies.

RESULTS

Eleven of 12 cases with no history of preoperative chemotherapy showed weakly positive or negative staining for HSP27, whereas six and five cases were strongly positive for alphaA and alphaB-crystallin, respectively. In the six cases with a history of chemotherapy, several viable retinoblastoma cells remained. Immunoreactivity for HSP27 and alphaB-crystallin was strongly detected in the cytoplasm of viable retinoblastoma cells, while alphaA-crystallin immunoreactivity was less marked. Immunoreactivity for HSP27 was significantly higher in retinoblastoma cases with preoperative chemotherapy than in those without chemotherapy (p<0.0001). In contrast, immunoreactivity for alphaA-crystallin was significantly lower in cases with chemotherapy than in cases without chemotherapy (p<0.01).

CONCLUSIONS

HSP27 and alphaB-crystallin, but not alphaA-crystallin, were highly expressed in viable tumour cells after chemotherapy, suggesting that HSP27 and alphaB-crystallin may protect tumour cells from apoptotic signals produced by anticancer drugs in retinoblastoma.

Identification of a protective role for protein phosphatase 1cgamma1 against oxidative stress-induced vascular smooth muscle cell apoptosis

The development of therapeutic strategies to inhibit reactive oxygen species (ROS)-mediated damage in blood vessels has been limited by a lack of specific targets for intervention. Targeting ROS-mediated events in the vessel wall is of interest, because ROS play important roles throughout atherogenesis. In early atherosclerosis, ROS stimulate vascular smooth muscle cell (VSMC) growth, whereas in late stages of lesion development, ROS induce VSMC apoptosis, causing atherosclerotic plaque instability. To identify putative protective genes against oxidative stress, mouse aortic VSMC were infected with a retroviral human heart cDNA expression library, and apoptosis was induced in virus-infected cells by 2,3-dimethoxy-1,4-naphthoquinone (DMNQ) treatment. A total of 17 different, complete cDNAs were identified from the DMNQ-resistant VSMC clones by PCR amplification and sequencing. The cDNA encoding PP1cgamma1 (catalytic subunit of protein phosphatase 1) was present in several independent DMNQ-resistant VSMC clones. DMNQ increased mitochondrial ROS production, caspase-3/7 activity, DNA fragmentation, and decreased mitochondrial transmembrane potential in VSMC while decreasing PP1cgamma1 activity and expression. Depletion of PP1cgamma1 expression by short hairpin RNA significantly enhanced basal as well as DMNQ-induced VSMC apoptosis. PP1cgamma1 overexpression abrogated DMNQ-induced JNK1 activity, p53 Ser(15) phosphorylation, and Bax expression and protected VSMC against DMNQ-induced apoptosis. In addition, PP1cgamma1 overexpression attenuated DMNQ-induced caspase-3/7 activation and DNA fragmentation. Inhibition of p53 protein expression using small interfering RNA abrogated DMNQ-induced Bax expression and significantly attenuated VSMC apoptosis. Together, these data indicate that PP1cgamma1 overexpression promotes VSMC survival by interfering with JNK1 and p53 phosphorylation cascades involved in apoptosis.

PKB and the mitochondria: AKTing on apoptosis

Cellular homeostasis depends upon the strict regulation of responses to external stimuli, such as signalling cascades triggered by nutrients and growth factors, and upon cellular metabolism. One of the major molecules coordinating complex signalling pathways is protein kinase B (PKB), a serine/threonine kinase also known as Akt. The number of substrates known to be phosphorylated by PKB and its interacting partners, as well as our broad understanding of how PKB is implicated in responses to growth factors, metabolic pathways, proliferation, and cell death via apoptosis is constantly increasing. Activated by the insulin/growth factor-phosphatidylinositol 3-kinase (PI3K) cascade, PKB triggers events that promote cell survival and prevent apoptosis. It is also now widely accepted that mitochondria are not just suppliers of ATP, but that they participate in regulatory and signalling events, responding to multiple physiological inputs and genetic stresses, and regulate both cell proliferation and death. Thus, mitochondria are recognized as important players in apoptotic events and it is logical to predict some form of interplay with PKB. In this review, we will summarize mechanisms by which PKB mediates its anti-apoptotic activities in cells and survey recent developments in understanding mitochondrial dynamics and their role during apoptosis.