Heat shock and other apoptosis-related proteins as therapeutic targets in prostate cancer

Exhaled breath condensates from healthy children induce cell death of in vitro cultured cells by activation of apoptosis

Introduction

Exhaled breath condensate (EBC) is a liquefied air, containing a mixture of non-volatile compounds, reflecting pathophysiological status of the bronchopulmonary system. Therefore, EBC analysis may be useful in diagnostics and monitoring of various respiratory diseases. In previous studies it was found that EBC from asthmatic children contained several regulators of angiogenesis. In vitro experiments with EBCs from children with asthma revealed their weak influence on proliferation of various cells. Surprisingly, EBCs from healthy children led to apoptosis of all tested cells.

Aim

To assess the expression of selected apoptosis-related proteins in human and murine cells exposed to EBC from healthy children.

Material and methods

EBCs from healthy children were added to cultures of murine endothelial cells (C166) or human lung fibroblasts (HLF) to induce their apoptosis. For proteome analysis the apoptosis pathway-specific protein microarrays were used.

Results

The homogenates from EBC-treated C166 cells contained low amounts of Hsp27, which correlated with their fast death. Contrary to C166, the lysates from EBC-treated fibroblasts displayed increased amounts of Hsp27, which correlated with delayed HLF response to the induction of apoptosis. Except for increased caspase-3 in EBC-treated HLF, none of the other apoptosis regulators revealed any significant changes in that analysis.

Conclusions

The screening of apoptosis pathways with microarray technology allowed identification of two molecules, Hsp27 and caspase-3, involved in cellular response to EBC. However, the factor responsible for induction of the cytotoxic effect of EBC from healthy children still remains unknown.

Prostate cancer and therapeutic challenges

Prostate cancer (PC) is the most prevalent type of cancer in men worldwide. In Saudi Arabia, the rate of PC is increasing annually. The sex steroid hormones androgens and their receptors have critical roles in PC development and progression. Additionally, apoptosis-related proteins such as heat-shock proteins are vital molecules in PC development. Steroid hormone-deprivation therapies remain the essential treatment for patients with metastatic PCs; however, acquired resistance to hormone deprivation and the transition to PC androgen independence is a major health obstacle. In this review, we aim to detail the roles of androgens, androgen receptors and sex steroid hormones in inducing apoptosis in PC.

Identification of potential molecular pathways involved in prostate carcinogenesis in offspring exposed to maternal malnutrition

The developmental origins of health and disease concept links adult diseases with early-life exposure to inappropriate environmental conditions. Intrauterine and postnatal malnutrition may lead to an increased incidence of type 2 diabetes, obesity, and cardiovascular diseases. Maternal malnutrition (MM) has also been associated with prostate carcinogenesis. However, the molecular mechanisms associated with this condition remain poorly understood. Using a proteomic analysis, we demonstrated that MM changed the levels of proteins associated with growth factors, estrogen signaling, detoxification, and energy metabolism in the prostate of both young and old rats. These animals also showed increased levels of molecular markers of endoplasmic reticulum function and histones. We further performed an in silico analysis that identified commonly deregulated proteins in the ventral prostate of old rats submitted to MM with a mouse model and patients with prostate cancer. In conclusion, our results demonstrated that estrogenic signaling pathways, endoplasmic reticulum functions, energy metabolism, and molecular sensors of protein folding and Ca2+ homeostasis, besides histone, and RAS-GTPase family appear to be involved in this process. Knowledge of these factors may raise discussions regarding the role of maternal dietary intervention as a public policy for the lifelong prevention of chronic diseases.

[Biology behavior of head and neck squamous cell cancer cells changes after knocking down heat shock protein 27]

OBJECTIVE

This study aimed to observe the metastatic behavior of head and neck squamous cell carcinoma cells after knocking down heat shock protein (Hsp) 27.

METHODS

The experiment was divided into three groups: the lentivirus vector plasmid of pLenti-shRNA-Hsp27 was transfected into UM-SCC-22B cells as experimental group (shHsp27 group), routine culture of UM-SCC-22B cells as blank control (ctrl group), UM-SCC-22B cells transfection of pLenti-shRNA-ctrl lentivirus vector as negative control (shctrl group). Through real-time quantitative polymerase chain reaction (RT-qPCR) and Western blot assay to detect the mRNA expression of Hsp27 in three groups. MTS assay was performed to detect cell-proliferation changes, wounding healing assay was performed to detect cell-migration changes, and Matrigel Transwell invasion assay was performed to detect cell-invasion changes.

RESULTS

The expression of Hsp27 in shHsp27 group decreased signifi-cantly; MTS assay showed that UM-SCC-22B before and after Hsp27 knockdown had similar proliferation rates after being cultured for 24 or 48 h. Compared with the ctrl group, the shHsp27 group decreased the metastatic behavior by 4.38-fold in migration and 2.03-fold in cell invasion.

CONCLUSIONS

Stably transfected lentivirus vector plasmid of pLenti-shRNA-Hsp27 can efficiently decrease Hsp27 expression and reduce the metastasis ability of UM-SCC-22B.

Divergent Modulation of Proteostasis in Prostate Cancer

Proteostasis regulates key cellular processes such as cell proliferation, differentiation, transcription, and apoptosis. The mechanisms by which proteostasis is regulated are crucial and the deterioration of cellular proteostasis has been significantly associated with tumorigenesis since it specifically targets key oncoproteins and tumor suppressors. Prostate cancer (PCa) is the second most common cause of cancer death in men worldwide. Androgens mediate one of the most central signaling pathways in all stages of PCa via the androgen receptor (AR). In addition to their regulation by hormones, PCa cells are also known to be highly secretory and are particularly prone to ER stress as proper ER function is essential. Alterations in various complex signaling pathways and cellular processes including cell cycle control, transcription, DNA repair, apoptosis, cell adhesion, epithelial-mesenchymal transition (EMT), and angiogenesis are critical factors influencing PCa development through key molecular changes mainly by posttranslational modifications in PCa-related proteins, including AR, NKX3.1, PTEN, p53, cyclin D1, and p27. Several ubiquitin ligases like MDM2, Siah2, RNF6, CHIP, and substrate-binding adaptor SPOP; deubiquitinases such as USP7, USP10, USP26, and USP12 are just some of the modifiers involved in the regulation of these key proteins via ubiquitin-proteasome system (UPS). Some ubiquitin-like modifiers, especially SUMOs, have been also closely associated with PCa. On the other hand, the proteotoxicity resulting from misfolded proteins and failure of ER adaptive capacity induce unfolded protein response (UPR) that is an indispensable signaling mechanism for PCa development. Lastly, ER-associated degradation (ERAD) also plays a crucial role in prostate tumorigenesis. In this section, the relationship between prostate cancer and proteostasis will be discussed in terms of UPS, UPR, SUMOylation, ERAD, and autophagy.

Changes in saliva proteins in two conditions of compromised welfare in pigs: An experimental induced stress by nose snaring and lameness

The aim of this study was to identify biological pathways and proteins differentially expressed in saliva of pigs in two conditions of compromised welfare: an acute stress consisting of restraint with a nose snare and in pigs with lameness which is a highly frequent problem in the swine industry. For this purpose, high-resolution quantitative proteomics based on Tandem Mass Tags labelling was used. Four proteins showed significant differences in the conditions of compromised welfare, namely cornulin, the heat shock protein 27 and lactate dehydrogenase (LDH), that showed significant increases, whereas immunoglobulin J chain showed a significant decrease. LDH, which was the protein that showed the highest differences, was selected for validation and clinical evaluation as a diagnostic biomarker. Significant changes in this protein were observed between pigs restrained with a nose snare and pigs with lameness compared with healthy pigs when measured with available commercial assays in a larger population of pigs. In conclusion, this study reports that in situations of compromised welfare on farm, such as acute stress and lameness in pigs, there are changes in proteins and metabolic pathways in saliva, and describes a series of proteins that could potentially be used as biomarkers for both short term acute stress and longer term chronic stress of lameness. These biomarkers would have the advantage of being measured in saliva by a noninvasive and not stressful collection sampling procedure.

Silencing of heat shock protein 27 increases the radiosensitivity of non‑small cell lung carcinoma cells

Radiotherapy is a useful treatment for malignant tumors, including lung carcinoma; however, non‑small cell lung carcinoma (NSCLC) is frequently insensitive to radiation. It has been reported that heat shock protein 27 (HSPB1) is a radioresistance‑associated protein in nasopharyngeal carcinoma. In the present study, the role of HSPB1 in NSCLC cells induced by irradiation was investigated. The viability of cells was determined by a Cell Counting Kit‑8 assay. The apoptotic activity, cell cycle distribution and mitochondrial membrane potential (MMP) of cells were evaluated via flow cytometry. Reverse transcription‑quantitative polymerase chain reaction and western blot analyses were employed to measure the expression of various genes and proteins. It was observed that knockdown of HSPB1 with small interfering RNA (si‑HSPB1) markedly decreased the viability of A549 NSCLC cells and induced cell cycle arrest in the G2/M phase following exposure to 6 Gy irradiation. Furthermore, it was revealed that si‑HSPB1 significantly downregulated cyclin B1 and cyclin G1 expression. Additionally, si‑HSPB1 promoted apoptosis and depolarized the MMP of cells exposed to 6 Gy irradiation. The expression levels of B‑cell lymphoma‑2 (Bcl‑2), mitochondrial cytochrome c (cyto c) and pro‑caspase‑8 were downregulated, whereas those of Bcl‑2 associated X protein (Bax), cytosolic cyto c and cleaved‑caspase‑8 were upregulated. Collectively, silencing of HSPB1 increased the radiosensitivity of NSCLC cells by reducing cell viability, depolarizing the MMP, arresting the cell cycle in the G2/M phase and promoting cell apoptosis. Therefore, HSPB1 may be a novel target for increasing radiosensitivity in the treatment of NSCLC.

Androgen receptor and heat shock protein 27 co-regulate the malignant potential of molecular apocrine breast cancer

Background

The most striking feature of molecular apocrine breast cancer (MABC) is the expression of androgen receptor (AR). We report here the mechanism of the AR in regulating the behavior of MABC.

Methods

The MABC cell line, MDA-MB-453, and the nonMABC cell line, MCF7, were used in this study. The effect of dihydrotestosterone (DHT) and heat shock protein 27 (HSP27) on cell proliferation was quantified using the cell counter kit-8 (CCK8) and clonogenic assays in vitro and by a xenograft tumor model in vivo. The expression of the AR and HSP27 was analyzed using western blot, qPCR, and immunofluorescence assays. Complexes of the AR and HSP27 were detected by co-immunoprecipitation (Co-IP).

Results

In MDA-MB-453 cells, DHT promoted cell proliferation and stimulated AR and HSP27 translocation from the cytoplasm to the nucleus, whereas, it inhibited MCF7 cell growth, and only the AR translocated into the nucleus. HSP27 knock-down decreased the proliferative ability of MDA-MB-453 cells, which could be rescued by DHT, while HSP27 and DHT had synergistic effects on MCF7 cells. HSP27 phosphorylation was a prerequisite for AR translocation into the nucleus, especially phosphorylation on serine 82. In addition, DHT stimulated the tumorigenic and metastatic capacities of MDA-MB-453 cells, while HSP27 knock-down decreased the rate of tumor formation and induced apoptosis in cells.

Conclusions

The results suggest that HSP27 assists the AR in regulating the malignant behavior of MABC, and these findings might be helpful in the treatment of MABC.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-0762-y) contains supplementary material, which is available to authorized users.

The epitranscriptome m6A writer METTL3 promotes chemo- and radioresistance in pancreatic cancer cells

N6-methyladenosine (m6A) is the most abundant epitranscriptome modification in mammalian mRNA. Recent years have seen substantial progress in m6A epitranscriptomics, indicating its crucial roles in the initiation and progression of cancer through regulation of RNA stabilities, mRNA splicing, microRNA processing and mRNA translation. However, by what means m6A is dynamically regulated or written by enzymatic components represented by methyltransferase-like 3 (METTL3) and how m6A is significant for each of the numerous genes remain unclear. We focused on METTL3 in pancreatic cancer, the prognosis of which is not satisfactory despite the development of multidisciplinary therapies. We established METTL3-knockdown pancreatic cancer cell line using short hairpin RNA. Although morphologic and proliferative changes were unaffected, METTL3-depleted cells showed higher sensitivity to anticancer reagents such as gemcitabine, 5-fluorouracil, cisplatin and irradiation. Our data suggest that METTL3 is a potent target for enhancing therapeutic efficacy in patients with pancreatic cancer. In addition, we performed cDNA expression analysis followed by gene ontology and protein-protein interaction analysis using the Database for Annotation, Visualization, and Integrated Discovery and Search Tool for the Retrieval of Interacting Genes/Proteins databases, respectively. The results demonstrate that METTL3 was associated with mitogen-activated protein kinase cascades, ubiquitin-dependent process and RNA splicing and regulation of cellular process, suggesting functional roles and targets of METTL3.

Pachymic acid inhibits the tumorigenicity of gastric cancer cells by the mitochondrial pathway

Pachymic acid (PA), a lanostane-type triterpenoid derived from traditional Chinese herbals, has been reported to have antitumor activity in versatile cancer cells. However, the antitumor effect of PA in gastric cancer (GC) cells remains unclear. In this study, we aimed to explore the efficacy and mechanisms of PA in GC. The antiproliferative effect of PA was assessed by a growth assay and a colony formation assay. Flow cytometry was used to detect changes in cell cycle distribution. Apoptosis was assessed by an annexin V/propidium iodide double-staining assay. The expressions of the apoptosis-related proteins were measured by western blot. The mitochondrial capacity was observed by immunostaining of Mito Tracker Red and mitochondrial function protein MT. Xenograft models of GC were constructed by a subcutaneous injection of SGC-7901 and MKN-49P cells pretreated with PA. PA could potently inhibit GC cell growth and colony formation. PA significantly induced G1, G2/M, and inhibited G0 phase arrest in GC cell lines SGC-7901 and MKN-49P. PA induced cell apoptosis by regulating the expressions of apoptosis-related proteins (caspase-3, PARP, Bcl-2, and Bax) and suppressing the mitochondrial capacity of GC cell lines in vitro in a dose-dependent manner. In addition, PA suppressed the tumor growth of xenograft models of GC and prolonged the survival of animals markedly. In brief, the present study shows that PA induces apoptosis through inhibition of mitochondrial capacity in human GC cells. Our findings suggest that PA may have therapeutic potential in GC.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

LEDGF/p75 Overexpression Attenuates Oxidative Stress-Induced Necrosis and Upregulates the Oxidoreductase ERP57/PDIA3/GRP58 in Prostate Cancer

Prostate cancer (PCa) mortality is driven by highly aggressive tumors characterized by metastasis and resistance to therapy, and this aggressiveness is mediated by numerous factors, including activation of stress survival pathways in the pro-inflammatory tumor microenvironment. LEDGF/p75, also known as the DFS70 autoantigen, is a stress transcription co-activator implicated in cancer, HIV-AIDS, and autoimmunity. This protein is targeted by autoantibodies in certain subsets of patients with PCa and inflammatory conditions, as well as in some apparently healthy individuals. LEDGF/p75 is overexpressed in PCa and other cancers, and promotes resistance to chemotherapy-induced cell death via the transactivation of survival proteins. We report in this study that overexpression of LEDGF/p75 in PCa cells attenuates oxidative stress-induced necrosis but not staurosporine-induced apoptosis. This finding was consistent with the observation that while LEDGF/p75 was robustly cleaved in apoptotic cells into a p65 fragment that lacks stress survival activity, it remained relatively intact in necrotic cells. Overexpression of LEDGF/p75 in PCa cells led to the upregulation of transcript and protein levels of the thiol-oxidoreductase ERp57 (also known as GRP58 and PDIA3), whereas its depletion led to ERp57 transcript downregulation. Chromatin immunoprecipitation and transcription reporter assays showed LEDGF/p75 binding to and transactivating the ERp57 promoter, respectively. Immunohistochemical analysis revealed significantly elevated co-expression of these two proteins in clinical prostate tumor tissues. Our results suggest that LEDGF/p75 is not an inhibitor of apoptosis but rather an antagonist of oxidative stress-induced necrosis, and that its overexpression in PCa leads to ERp57 upregulation. These findings are of significance in clarifying the role of the LEDGF/p75 stress survival pathway in PCa.

PARK7/DJ-1 dysregulation by oxidative stress leads to magnesium deficiency: implications in degenerative and chronic diseases

Disturbed magnesium (Mg(2+)) homoeostasis and increased levels of OS (oxidative stress) are associated with poor clinical outcomes in patients suffering from neurodegenerative, cardiovascular and metabolic diseases. Data from clinical and animal studies suggest that MD (Mg(2+) deficiency) is correlated with increased production of ROS (reactive oxygen species) in cells, but a straightforward causal relationship (including molecular mechanisms) between the two conditions is lacking. The multifactorial protein PARK7/DJ-1 is a major antioxidant protein, playing a key role in cellular redox homoeostasis, and is a positive regulator of AR (androgen receptor)-dependent transcription. SLC41A1 (solute carrier family 41 member 1), the gene encoding a ubiquitous cellular Mg(2+)E (Mg(2+)efflux) system, has been shown to be regulated by activated AR. We hypothesize that overexpression/up-regulation of PARK7/DJ-1, attributable to OS and related activation of AR, is an important event regulating the expression of SLC41A1 and consequently, modulating the Mg(2+)E capacity. This would involve changes in the transcriptional activity of PARK7/DJ-1, AR and SLC41A1, which may serve as biomarkers of intracellular MD and may have clinical relevance. Imipramine, in use as an antidepressant, has been shown to reduce the Mg(2+)E activity of SLC41A1 and OS. We therefore hypothesize further that administration of imipramine or related drugs will be beneficial in MD- and OS-associated diseases, especially when combined with Mg(2+) supplementation. If proved true, the OS-responsive functional axis, PARK7/DJ-1-AR-SLC41A1, may be a putative mechanism underlying intracellular MD secondary to OS caused by pro-oxidative stimuli, including extracellular MD. Furthermore, it will advance our understanding of the link between OS and MD.

Role of calpastatin in the regulation of mRNA expression of calpain, caspase, and heat shock protein systems in bovine muscle satellite cells

Calpastatin participates in apoptotic cell death and cell signaling, but its role in skeletal myoblast development and molecular involvements in cell growth still remains unknown. The current study aimed to investigate the role of calpastatin on the expression patterns of calpains, caspases, and heat shock proteins (HSPs). In addition, the cell viability during myoblast growth under calpastatin silence condition was also investigated. Three small interference RNA sequences (siRNAs) were used to silence calpastatin gene and ligated into pSilencer plasmid vector to construct short hairpin RNA (shRNA) expression. The all three siRNAs significantly silence the calpastatin gene. Moreover, suppression of calpastatin significantly reduced the viability of myoblasts during growth phase when compared to control cells. Additionally, knockdown of calpastatin significantly increased the mRNA expression of μ-calpain, caspase-3, caspase-7, and caspase-9, as well as HSP-27, -70, and -90. The present study results suggested that the suppression of calpastatin resulted in the increased expression of μ-calpain, caspases, and HSPs which in turn regulate the apoptotic cell death. The present study throws light on the central role of calpastatin in the control of calpain activity, cell proliferation, cell survival, and apoptotic pathways.