Heat shock protein 27 increases after androgen ablation and plays a cytoprotective role in hormone-refractory prostate cancer

Heat Shock Response and Heat Shock Proteins: Current Understanding and Future Opportunities in Human Diseases

The heat shock response is an evolutionarily conserved mechanism that protects cells or organisms from the harmful effects of various stressors such as heat, chemicals toxins, UV radiation, and oxidizing agents. The heat shock response triggers the expression of a specific set of genes and proteins known as heat shock genes/proteins or molecular chaperones, including HSP100, HSP90, HSP70, HSP60, and small HSPs. Heat shock proteins (HSPs) play a crucial role in thermotolerance and aiding in protecting cells from harmful insults of stressors. HSPs are involved in essential cellular functions such as protein folding, eliminating misfolded proteins, apoptosis, and modulating cell signaling. The stress response to various environmental insults has been extensively studied in organisms from prokaryotes to higher organisms. The responses of organisms to various environmental stressors rely on the intensity and threshold of the stress stimuli, which vary among organisms and cellular contexts. Studies on heat shock proteins have primarily focused on HSP70, HSP90, HSP60, small HSPs, and ubiquitin, along with their applications in human biology. The current review highlighted a comprehensive mechanism of heat shock response and explores the function of heat shock proteins in stress management, as well as their potential as therapeutic agents and diagnostic markers for various diseases.

Molecular features of prostate cancer after neoadjuvant therapy in the phase 3 CALGB 90203 trial

BACKGROUND

The phase 3 CALGB 90203 (Alliance) trial evaluated neoadjuvant chemohormonal therapy for high-risk localized prostate cancer before radical prostatectomy. We dissected the molecular features of post-treated tumors with long-term clinical outcomes to explore mechanisms of response and resistance to chemohormonal therapy.

METHODS

We evaluated 471 radical prostatectomy tumors, including 294 samples from 166 patients treated with 6 cycles of docetaxel plus androgen deprivation therapy before radical prostatectomy and 177 samples from 97 patients in the control arm (radical prostatectomy alone). Targeted DNA sequencing and RNA expression of tumor foci and adjacent noncancer regions were analyzed in conjunction with pathologic changes and clinical outcomes.

RESULTS

Tumor fraction estimated from DNA sequencing was significantly lower in post-treated tumor tissues after chemohormonal therapy compared with controls. Higher tumor fraction after chemohormonal therapy was associated with aggressive pathologic features and poor outcomes, including prostate-specific antigen-progression-free survival. SPOP alterations were infrequently detected after chemohormonal therapy, while TP53 alterations were enriched and associated with shorter overall survival. Residual tumor fraction after chemohormonal therapy was linked to higher expression of androgen receptor-regulated genes, cell cycle genes, and neuroendocrine genes, suggesting persistent populations of active prostate cancer cells. Supervised clustering of post-treated high-tumor-fraction tissues identified a group of patients with elevated cell cycle-related gene expression and poor clinical outcomes.

CONCLUSIONS

Distinct recurrent prostate cancer genomic and transcriptomic features are observed after exposure to docetaxel and androgen deprivation therapy. Tumor fraction assessed by DNA sequencing quantifies pathologic response and could be a useful trial endpoint or prognostic biomarker. TP53 alterations and high cell cycle transcriptomic activity are linked to aggressive residual disease, despite potent chemohormonal therapy.

ZNF703 mRNA-Targeting Antisense Oligonucleotide Blocks Cell Proliferation and Induces Apoptosis in Breast Cancer Cell Lines

The luminal B molecular subtype of breast cancers (BC) accounts for more than a third of BCs and is associated with aggressive clinical behavior and poor prognosis. The use of endocrine therapy in BC treatment has significantly contributed to the decrease in the number of deaths in recent years. However, most BC patients with prolonged exposure to estrogen receptor (ER) selective modulators such as tamoxifen develop resistance and become non-responsive over time. Recent studies have implicated overexpression of the ZNF703 gene in BC resistance to endocrine drugs, thereby highlighting ZNF703 inhibition as an attractive modality in BC treatment, especially luminal B BCs. However, there is no known inhibitor of ZNF703 due to its nuclear association and non-enzymatic activity. Here, we have developed an antisense oligonucleotide (ASO) against ZNF703 mRNA and shown that it downregulates ZNF703 protein expression. ZNF703 inhibition decreased cell proliferation and induced apoptosis. Combined with cisplatin, the anti-cancer effects of ZNF703-ASO9 were improved. Moreover, our work shows that ASO technology may be used to increase the number of targetable cancer genes.

Cargo-selective and adaptive delivery of nucleic acid therapeutics by bola-amphiphilic dendrimers

Nucleic acid therapeutics are becoming an important drug modality, offering the unique opportunity to address "undruggable" targets, respond rapidly to evolving pathogens, and treat diseases at the gene level for precision medicine. However, nucleic acid therapeutics have poor bioavailability and are chemolabile and enzymolabile, imposing the need for delivery vectors. Dendrimers, by virtue of their well-defined structure and cooperative multivalence, represent precision delivery systems. We synthesized and studied bola-amphiphilic dendrimers for cargo-selective and on-demand delivery of DNA and small interfering RNA (siRNA), both important nucleic acid therapeutics. Remarkably, superior performances were achieved for siRNA delivery with the second-generation dendrimer, yet for DNA delivery with the third generation. We systematically studied these dendrimers with regard to cargo binding, cellular uptake, endosomal release, and in vivo delivery. Differences in size both of the dendrimers and their nucleic acid cargos impacted the cooperative multivalent interactions for cargo binding and release, leading to cargo-adaptive and selective delivery. Moreover, both dendrimers harnessed the advantages of lipid and polymer vectors, while offering nanotechnology-based tumor targeting and redox-responsive cargo release. Notably, they allowed tumor- and cancer cell-specific delivery of siRNA and DNA therapeutics for effective treatment in different cancer models, including aggressive and metastatic malignancies, outperforming the currently available vectors. This study provides avenues to engineer tailor-made vectors for nucleic acid delivery and precision medicine.

Impact of Non-Invasive Physical Plasma on Heat Shock Protein Functionality in Eukaryotic Cells

Recently, biomedical research has increasingly investigated physical plasma as an innovative therapeutic approach with a number of therapeutic biomedical effects. It is known from radiation and chemotherapy that these applications can lead to the induction and activation of primarily cytoprotective heat shock proteins (HSP). HSP protect cells and tissues from physical, (bio)chemical, and physiological stress and, ultimately, along with other mechanisms, govern resistance and treatment failure. These mechanisms are well known and comparatively well studied in drug therapy. For therapies in the field of physical plasma medicine, however, extremely little data are available to date. In this review article, we provide an overview of the current studies on the interaction of physical plasma with the cellular HSP system.

Chaperone-mediated autophagy promotes PCa survival during ARPI through selective proteome remodeling

The androgen receptor (AR) plays an important role in PCa metabolism, with androgen receptor pathway inhibition (ARPI) subjecting PCa cells to acute metabolic stress caused by reduced biosynthesis and energy production. Defining acute stress response mechanisms that alleviate ARPI stress and therefore mediate prostate cancer (PCa) treatment resistance will help improve therapeutic outcomes of patients treated with ARPI. We identified the up-regulation of chaperone-mediated autophagy (CMA) in response to acute ARPI stress, which persisted in castration-resistant PCa (CRPC); previously undefined in PCa. CMA is a selective protein degradation pathway and a key stress response mechanism up-regulated under several stress stimuli, including metabolic stress. Through selective protein degradation, CMA orchestrates the cellular stress response by regulating cellular pathways through selective proteome remodeling. Through broad-spectrum proteomic analysis, CMA coordinates metabolic reprogramming of PCa cells to sustain PCa growth and survival during ARPI; through the upregulation of mTORC1 signaling and pathways associated with PCa biosynthesis and energetics. This not only promoted PCa growth during ARPI, but also promoted the emergence of CRPC in-vivo. During CMA inhibition, PCa metabolism is compromised, leading to ATP depletion, resulting in a profound anti-proliferative effect on PCa cells, and is enhanced when combined with ARPI. Furthermore, CMA inhibition prevented in-vivo tumour formation, and also re-sensitized enzalutamide-resistant cell lines in-vitro. The profound anti-proliferative effect of CMA inhibition was attributed to cell cycle arrest mediated through p53 transcriptional repression of E2F target genes. In summary, CMA is an acute ARPI stress response mechanism, essential in alleviating ARPI induced metabolic stress, essential for ensuring PCa growth and survival. CMA plays a critical role in the development of ARPI resistance in PCa.

DDX5 mRNA-targeting antisense oligonucleotide as a new promising therapeutic in combating castration-resistant prostate cancer

The heat shock protein 27 (Hsp27) has emerged as a principal factor of the castration-resistant prostate cancer (CRPC) progression. Also, an antisense oligonucleotide (ASO) against Hsp27 (OGX-427 or apatorsen) has been assessed in different clinical trials. Here, we illustrate that Hsp27 highly regulates the expression of the human DEAD-box protein 5 (DDX5), and we define DDX5 as a novel therapeutic target for CRPC treatment. DDX5 overexpression is strongly correlated with aggressive tumor features, notably with CRPC. DDX5 downregulation using a specific ASO-based inhibitor that acts on DDX5 mRNAs inhibits cell proliferation in preclinical models, and it particularly restores the treatment sensitivity of CRPC. Interestingly, through the identification and analysis of DDX5 protein interaction networks, we have identified some specific functions of DDX5 in CRPC that could contribute actively to tumor progression and therapeutic resistance. We first present the interactions of DDX5 and the Ku70/80 heterodimer and the transcription factor IIH, thereby uncovering DDX5 roles in different DNA repair pathways. Collectively, our study highlights critical functions of DDX5 contributing to CRPC progression and provides preclinical proof of concept that a combination of ASO-directed DDX5 inhibition with a DNA damage-inducing therapy can serve as a highly potential novel strategy to treat CRPC.

The endoplasmic reticulum stress response in prostate cancer

In order to proliferate in unfavourable conditions, cancer cells can take advantage of the naturally occurring endoplasmic reticulum-associated unfolded protein response (UPR) via three highly conserved signalling arms: IRE1α, PERK and ATF6. All three arms of the UPR have key roles in every step of tumour progression: from cancer initiation to tumour growth, invasion, metastasis and resistance to therapy. At present, no cure for metastatic prostate cancer exists, as targeting the androgen receptor eventually results in treatment resistance. New research has uncovered an important role for the UPR in prostate cancer tumorigenesis and crosstalk between the UPR and androgen receptor signalling pathways. With an improved understanding of the mechanisms by which cancer cells exploit the endoplasmic reticulum stress response, targetable points of vulnerability can be uncovered.

HSP27/Menin Expression as New Prognostic Serum Biomarkers of Prostate Cancer Aggressiveness Independent of PSA

The screening of PCa is based on two tests, the total PSA test and the rectal examination. However, PSA is not specific for PCa stage confirmation, leading in false positive result and involving PCa over-diagnosis and over-treatment. HSP27 and Menin have been found to be overexpressed in a wide range of human cancers. Recent studies showed how HSP27 interacts with and stabilizes Menin to lead PCa progression and treatment resistance. The purpose of our study was to evaluate the correlation of HSP27 and Menin molecular expression, and their prognosis value in PCa with respect to clinicopathological features. Elisa was employed to measure serum HSP27 and Menin concentrations in 73 PCa patients and 80 healthy individuals. Immunohistochemistry (IHC) was used to determine HSP27 and Menin tissue expression in 57 tumors and 4 Benign Prostatic Hyperplasia (BPH) tissues. Serum HSP27 expression correlated with its tissue expression in all PCa patients, whereas serum Menin expression correlated only with tissue expression in aggressive PCa patients. Moreover, the results showed a positive correlation between HSP27 and Menin either in serum (r = 0.269; p = 0.021) or in tissue (r = 0.561; p < 0.0001). In aggressive PCa, serum expression of HSP27 and Menin was positively correlated (r = 0.664; R = 0.441; p = 0.001). The correlation between HSP27 and Menin expression in tissue was found only in patients with aggressive PCa (r = 0.606; R = 0.367; p = 0.004). Statistical analysis showed that the expression of both biomarkers was positively correlated with the hormone resistance or sensitivity, tumor aggressiveness, metastasis, Gleason Score, death and did not significantly correlate with age and PSA. Survival was illustrated by Kaplan−Meier curves; increased HSP27 and Menin expression correlated with shorter survival of PCa patients (p = 0.001 and p < 0.0001, respectively). Accuracy in predicting aggressiveness was quantified by the Area Under the Curve (AUC) of Receiver Operating Characteristic (ROC). We demonstrated that the combination of HSP27/Menin was statistically greater than PSA; it achieved an AUC of 0.824 (95% CI, 0.730−0.918; p < 0.0001). However, HSP27/Menin/PSA combination decreased the diagnostic value with an AUC of 0.569 (95% CI, 0.428−0.710; p = 0.645). Our work suggests the potential role of HSP27/Menin as diagnostic and prognostic biomarkers.

Heat Shock Protein 27 Affects Myeloid Cell Activation and Interaction with Prostate Cancer Cells

Heat shock proteins are cytoprotective molecules induced by environmental stresses. The small heat shock protein 27 (Hsp27) is highly expressed under oxidative stress conditions, mediating anti-oxidative effects and blocking apoptosis. Since medical gas plasma treatment subjects cancer cells to a multitude of reactive oxygen species (ROS), inducing apoptosis and immunomodulation, probable effects of Hsp27 should be investigated. To this end, we quantified the extracellular Hsp27 in two prostate cancer cell lines (LNCaP, PC-3) after gas plasma-induced oxidative stress, showing a significantly enhanced release. To investigate immunomodulatory effects, two myeloid cell lines (THP-1 and HL-60) were also exposed to Hsp27. Only negligible effects on viability, intracellular oxidative milieu, and secretion profiles of the myeloid cells were found when cultured alone. Interestingly, prostate cancer-myeloid cell co-cultures showed altered secretion profiles with a significant decrease in vascular endothelial growth factor (VEGF) release. Furthermore, the myeloid surface marker profiles were changed, indicating an enhanced differentiation in co-culture upon Hsp27 treatment. Finally, we investigated morphological changes, proliferation, and interaction with prostate cancer cells, and found significant alterations in the myeloid cells, supporting the tendency to differentiate. Collectively, our results suggest an ambiguous effect of Hsp27 on myeloid cells in the presence of prostate cancer cells which needs to be further investigated.

Impact of phosphorylation of heat shock protein 27 on the expression profile of periodontal ligament fibroblasts during mechanical strain

PURPOSE

Orthodontic tooth movement is a complex process involving the remodeling of extracellular matrix and bone as well as inflammatory processes. During orthodontic treatment, sterile inflammation and mechanical loading favor the production of receptor activator of NF-κB ligand (RANKL). Simultaneously, expression of osteoprotegerin (OPG) is inhibited. This stimulates bone resorption on the pressure side. Recently, heat shock protein 27 (HSP27) was shown to be expressed in the periodontal ligament after force application and to interfere with inflammatory processes.

METHODS

We investigated the effects of phosphorylated HSP27 on collagen synthesis (COL1A2 mRNA), inflammation (IL1B mRNA, IL6 mRNA, PTGS2 protein) and bone remodeling (RANKL protein, OPG protein) in human periodontal ligament fibroblasts (PDLF) without and with transfection of a plasmid mimicking permanent phosphorylation of HSP27 using real-time quantitative polymerase chain reaction (RT-qPCR), western blot and enzyme-linked immunosorbent assays (ELISAs). Furthermore, we investigated PDLF-induced osteoclastogenesis after compressive strain in a co-culture model with human macrophages.

RESULTS

In particular, phosphorylated HSP27 increased gene expression of COL1A2 and protein expression of PTGS2, while IL6 mRNA levels were reduced. Furthermore, we observed an increasing effect on the RANKL/OPG ratio and osteoclastogenesis mediated by PDLF.

CONCLUSION

Phosphorylation of HSP27 may therefore be involved in the regulation of orthodontic tooth movement by impairment of the sterile inflammation response and osteoclastogenesis.

Regulation of AR mRNA translation in response to acute AR pathway inhibition

We report a new mechanism of androgen receptor (AR) mRNA regulation and cytoprotection in response to AR pathway inhibition (ARPI) stress in prostate cancer (PCA). AR mRNA translation is coordinately regulated by RNA binding proteins, YTHDF3 and G3BP1. Under ambient conditions m6A-modified AR mRNA is bound by YTHDF3 and translationally stimulated, while m6A-unmodified AR mRNA is bound by G3BP1 and translationally repressed. When AR-regulated PCA cell lines are subjected to ARPI stress, m6A-modified AR mRNA is recruited from actively translating polysomes (PSs) to RNA-protein stress granules (SGs), leading to reduced AR mRNA translation. After ARPI stress, m6A-modified AR mRNA liquid–liquid phase separated with YTHDF3, while m6A-unmodified AR mRNA phase separated with G3BP1. Accordingly, these AR mRNA messages form two distinct YTHDF3-enriched or G3BP1-enriched clusters in SGs. ARPI-induced SG formation is cell-protective, which when blocked by YTHDF3 or G3BP1 silencing increases PCA cell death in response to ARPI stress. Interestingly, AR mRNA silencing also delays ARPI stress-induced SG formation, highlighting its supportive role in triggering this stress response. Our results define a new mechanism for stress adaptive cell survival after ARPI stress involving SG-regulated translation of AR mRNA, mediated by m6A RNA modification and their respective regulatory proteins.

High fibroblast-activation-protein expression in castration-resistant prostate cancer supports the use of FAPI-molecular theranostics

PURPOSE

To evaluate fibroblast-activation-protein (FAP) expression in different clinical stages of prostate cancer (PC) with regards to utility of [68 Ga]Ga-FAPI-04 PET/CT imaging in patients with castration-resistant PC (CRPC).

METHODS

Tissue microarrays (TMAs) were constructed from prostatic tissue from 94 patients at different stages of PC (primary PC, patients undergoing neoadjuvant androgen deprivation therapy, CRPC, and neuroendocrine PC (NEPC)) and were stained with anti-FAP monoclonal antibody. A positive pixel count algorithm (H-Index) was used to compare FAP expression between the groups. Additionally, three men with advanced CRPC or NEPC underwent [68 Ga]Ga-FAPI-04 PET/CT, and PET positivity was analyzed.

RESULTS

The mean H-index for benign tissue, primary PC, neoadjuvant androgen deprivation therapy before radical prostatectomy, CRPC, and NEPC was 0.018, 0.031, 0.042, 0.076, and 0.051, respectively, indicating a significant rise in FAP expression with advancement of disease. Corroborating these findings [68 Ga]Ga-FAPI-04 PET/CT was highly positive in men with advanced CRPC.

CONCLUSION

Increased FAP tissue expression supports the use of FAP inhibitor (FAPI)-molecular theranostics in CRPC.

Menin inhibition suppresses castration-resistant prostate cancer and enhances chemosensitivity

Disease progression and therapeutic resistance of prostate cancer (PC) are linked to multiple molecular events that promote survival and plasticity. We previously showed that heat shock protein 27 (HSP27) acted as a driver of castration-resistant phenotype (CRPC) and developed an oligonucleotides antisense (ASO) against HSP27 with evidence of anti-cancer activity in men with CRPC. Here, we show that the tumor suppressor Menin (MEN1) is highly regulated by HSP27. Menin is overexpressed in high-grade PC and CRPC. High MEN1 mRNA expression is associated with decreased biochemical relapse-free and overall survival. Silencing Menin with ASO technology inhibits CRPC cell proliferation, tumor growth, and restores chemotherapeutic sensitivity. ChIP-seq analysis revealed differential DNA binding sites of Menin in various prostatic cells, suggesting a switch from tumor suppressor to oncogenic functions in CRPC. These data support the evaluation of ASO against Menin for CRPC.

Inhibition of Scavenger Receptor Class B Type 1 (SR-B1) Expression and Activity as a Potential Novel Target to Disrupt Cholesterol Availability in Castration-Resistant Prostate Cancer

There have been several studies that have linked elevated scavenger receptor class b type 1 (SR-B1) expression and activity to the development and progression of castration-resistant prostate cancer (CRPC). SR-B1 facilitates the influx of cholesterol to the cell from lipoproteins in systemic circulation. This influx of cholesterol may be important for many cellular functions, including the synthesis of androgens. Castration-resistant prostate cancer tumors can synthesize androgens de novo to supplement the loss of exogenous sources often induced by androgen deprivation therapy. Silencing of SR-B1 may impact the ability of prostate cancer cells, particularly those of the castration-resistant state, to maintain the intracellular supply of androgens by removing a supply of cholesterol. SR-B1 expression is elevated in CRPC models and has been linked to poor survival of patients. The overarching belief has been that cholesterol modulation, through either synthesis or uptake inhibition, will impact essential signaling processes, impeding the proliferation of prostate cancer. The reduction in cellular cholesterol availability can impede prostate cancer proliferation through both decreased steroid synthesis and steroid-independent mechanisms, providing a potential therapeutic target for the treatment of prostate cancer. In this article, we discuss and highlight the work on SR-B1 as a potential novel drug target for CRPC management.

Heat Shock Proteins 27, 70, and 110: Expression and Prognostic Significance in Colorectal Cancer

Heat shock proteins (HSPs) are evolutionarily conserved chaperones occurring in virtually all living organisms playing a key role in the maintenance of cellular homeostasis. They are constitutively expressed to prevent and repair protein damage following various physiological and environmental stressors. HSPs are overexpressed in various types of cancers to provide cytoprotective function, and they have been described to influence prognosis and response to therapy. Moreover, they have been used as a tumor marker in blood serum biochemistry and they represent a potentially promising therapeutic target. To clarify prognostic significance of two canonical HSPs (27 and 70) and less known HSP110 (previously known as HSP105) in colorectal carcinoma (CRC), we retrospectively performed HSP immunohistochemistry on tissue microarrays from formalin-fixed paraffin-embedded tumor tissue from 297 patients with known follow-up. Survival analysis (univariate Kaplan-Meier analysis with the log-rank test and multivariate Cox regression) revealed significantly shorter overall survival (OS, mean 5.54 vs. 7.07, p = 0.033) and borderline insignificantly shorter cancer specific survival (CSS, mean 6.3 vs. 7.87 years, p = 0.066) in patients with HSP70+ tumors. In the case of HSP27+ tumors, there was an insignificantly shorter OS (mean 6.36 vs. 7.13 years, p = 0.2) and CSS (mean 7.17 vs. 7.95 years, p = 0.2). HSP110 showed no significant impact on survival. Using Pearson's chi-squared test, there was a significant association of HSP27 and HSP70 expression with advanced cancer stage. HSP27+ tumors were more frequently mismatch-repair proficient and vice versa (p = 0.014), and they occurred more often in female patients and vice versa (p = 0.015). There was an enrichment of left sided tumors with HSP110+ compared to the right sided (p = 0.022). In multivariate Cox regression adjusted on the UICC stage, grade and right/left side; both HSPs 27 and 70 were not independent survival predictors (p = 0.616 & p = 0.586). In multivariate analysis, only advanced UICC stage (p = 0) and right sided localization (p = 0.04) were independent predictors of worse CSS. In conclusion, from all three HSPs examined in our study, only HSP70 expression worsened CRC prognosis, although stage-dependent. The contribution of this article may be seen as a large survival analysis of HSPs 27 and 70 and the largest analysis of HSP110 described in CRC.

Drug-Like Small Molecule HSP27 Functional Inhibitor Sensitizes Lung Cancer Cells to Gefitinib or Cisplatin by Inducing Altered Cross-Linked Hsp27 Dimers

Relationships between heat shock protein 27 (HSP27) and cancer aggressiveness, metastasis, drug resistance, and poor patient outcomes in various cancer types including non-small cell lung cancer (NSCLC) were reported, and inhibition of HSP27 expression is suggested to be a possible strategy for cancer therapy. Unlike HSP90 or HSP70, HSP27 does not have an ATP-binding pocket, and no effective HSP27 inhibitors have been identified. Previously, NSCLC cancer cells were sensitized to radiation and chemotherapy when co-treated with small molecule HSP27 functional inhibitors such as zerumbone (ZER), SW15, and J2 that can induce abnormal cross-linked HSP27 dimer. In this study, cancer inhibition effects of NA49, a chromenone compound with better solubility, longer circulation time, and less toxicity than J2, were examined in combination with anticancer drugs such as cisplatin and gefitinib in NSCLC cell lines. When the cytotoxic drug cisplatin was treated in combination with NA49 in epidermal growth factor receptors (EGFRs) WT cell lines, sensitization was induced in an HSP27 expression-dependent manner. With gefitinib treatment, NA49 showed increased combination effects in both EGFR WT and Mut cell lines, also with HSP27 expression-dependent patterns. Moreover, NA49 induced sensitization in EGFR Mut cells with a secondary mutation of T790M when combined with gefitinib. Augmented tumor growth inhibition was shown with the combination of cisplatin or gefitinib and NA49 in nude mouse xenograft models. These results suggest the combination of HSP27 inhibitor NA49 and anticancer agents as a candidate for overcoming HSP27-mediated drug resistance in NSCLC patients.

Nucleoside-Lipid-Based Nanoparticles for Phenazine Delivery: A New Therapeutic Strategy to Disrupt Hsp27-eIF4E Interaction in Castration Resistant Prostate Cancer

Heat shock protein 27 (Hsp27) has an established role in tumor progression and chemo-resistance of castration-resistant prostate cancer (CRPC). Hsp27 protects eukaryotic translation initiation factor 4E (eIF4E) from degradation, thereby maintaining survival during treatment. Phenazine derivative compound #14 was demonstrated to specifically disrupt Hsp27/eIF4E interaction and significantly delay castration-resistant tumor progression in prostate cancer xenografts. In the present work, various strategies of encapsulation of phenazine #14 with either DOTAU (N-[5′-(2′,3′-dioleoyl)uridine]-N′,N′,N′-trimethylammonium tosylate) and DOU-PEG₂₀₀₀ (5′-PEG2000-2′,3′-dioleoyluridine) nucleolipids (NLs) were developed in order to improve its solubilization, biological activity, and bioavailability. We observed that NLs-encapsulated phenazine #14-driven Hsp27-eIF4E interaction disruption increased cytotoxic effects on castration-resistant prostate cancer cell line and inhibited tumor growth in castration-resistant prostate cancer cell xenografted mice compared to phenazine #14 and NLs alone. Phenazine #14 NL encapsulation might represent an interesting nanostrategy for CRPC therapy.

Molecular Chaperones in Osteosarcoma: Diagnosis and Therapeutic Issues

Osteosarcoma (OS) is the most common form of primary bone tumor affecting mainly children and young adults. Despite therapeutic progress, the 5-year survival rate is 70%, but it drops drastically to 30% for poor responders to therapies or for patients with metastases. Identifying new therapeutic targets is thus essential. Heat Shock Proteins (HSPs) are the main effectors of Heat Shock Response (HSR), the expression of which is induced by stressors. HSPs are a large family of proteins involved in the folding and maturation of other proteins in order to maintain proteostasis. HSP overexpression is observed in many cancers, including breast, prostate, colorectal, lung, and ovarian, as well as OS. In this article we reviewed the significant role played by HSPs in molecular mechanisms leading to OS development and progression. HSPs are directly involved in OS cell proliferation, apoptosis inhibition, migration, and drug resistance. We focused on HSP27, HSP60, HSP70 and HSP90 and summarized their potential clinical uses in OS as either biomarkers for diagnosis or therapeutic targets. Finally, based on different types of cancer, we consider the advantage of targeting heat shock factor 1 (HSF1), the major transcriptional regulator of HSPs in OS.

Upregulation of potential regulatory signaling molecules correlate with androgen receptor splice variants AR-V7 and AR-V567es in prostate cancer metastasis

AIM

Androgen receptor splice variants (AR-Vs) produced by alternative splicing of the AR play an important role in the treatment resistance and progression of prostate cancer (PCa). In this study, two most common AR variants and how they associate with the inflammatory response (NF-Kβ) and regulatory transcriptional activity (HSP-27) genes were investigated in patients with PCa and metastatic PCa (Met-PCa).

METHODS

Our study was carried out with the whole blood obtained from 25 healthy control subjects, 25 PCa patients and 39 Met-PCa patients. We examined the expression levels of AR, AR-V7 and AR-V567es genes via Real-time PCR and those of HSP-27 and NF-Kβ via ELISA method.

RESULTS

AR, AR-V7 and AR-V567es expressions were observed in 84.61%, 64.1%, 23.07% of Met-PCa patients respectively. The expression levels of full-length AR and variants (AR-V7 and AR-V567es) were associated with the prostate cancer stage. In the Met-PCa, the expression levels of AR, AR-V7 and AR-V567es were associated with the Gleason Scores but not with the PSA levels. AR-V7 expression levels in stage T4 patients significantly increased. NF-Kβ and HSP-27 protein levels were significantly higher in Met-PCa patients.

DISCUSSION

Our findings highlight the targeting of the proteostasis and inflammation pathways through inhibiting HSP-27 and NF-Kβ. This might be a valuable strategy to overcome anti-androgen resistance and improve drug therapy in Met-PCa patients whose gene expression levels of AR-V7 and AR-V567es variants are high.

Insight into Cisplatin-Resistance Signaling of W1 Ovarian Cancer Cells Emerges mTOR and HSP27 as Targets for Sensitization Strategies

The microenvironment possesses a strong impact on the tumor chemoresistance when cells bind to components of the extracellular matrix. Here we elucidate the signaling pathways of cisplatin resistance in W1 ovarian cancer cells binding to collagen type 1 (COL1) and signaling interference with constitutive cisplatin resistance in W1CR cells to discover the targets for sensitization. Proteome kinase arrays and Western blots were used to identify the signaling components, their impact on cisplatin resistance was evaluated by inhibitory or knockdown approaches. W1 cell binding to COL1 upregulates integrin-associated signals via FAK/PRAS40/mTOR, confirmed by β1-integrin (ITGB1) knockdown. mTOR appears as key for resistance, its blockade reversed COL1 effects on W1 cell resistance completely. W1CR cells compensate ITGB1-knockdown by upregulation of discoidin domain receptor 1 (DDR1) as alternative COL1 sensor. COL1 binding via DDR1 activates the MAPK pathway, of which JNK1/2 appears critical for COL1-mediated resistance. JNK1/2 inhibition inverts COL1 effects in W1CR cells, whereas intrinsic cisplatin resistance remained unaffected. Remarkably, knockdown of HSP27, another downstream MAPK pathway component overcomes intrinsic resistance completely sensitizing W1CR cells to the level of W1 cells for cisplatin cytotoxicity. Our data confirm the independent regulation of matrix-induced and intrinsic chemoresistance in W1 ovarian cancer cells and offer novel targets for sensitization.

Amphiphilic peptide dendrimer-based nanovehicles for safe and effective siRNA delivery

Small interfering RNA (siRNA)-based RNA interference has emerged as a promising therapeutic strategy for the treatment of a wide range of incurable diseases. However, the safe and effective delivery of siRNA therapeutics into the interior of target cells remains challenging. Here, we disclosed novel amphiphilic peptide dendrimers (AmPDs) that composed of hydrophobic two lipid-like alkyl chains and hydrophilic poly(lysine) dendrons with different generations (2C18-KK2 and 2C18-KK2K4) as nanovehicles for siRNA delivery. These AmPDs are able to self-assemble into supramolecular nanoassemblies that are capable of entrapping siRNA molecules into nanoparticles to protect siRNA from enzymatic degradation and promote efficient intracellular uptake without evident toxicity. Interestingly, by virtue of the optimal balance of hydrophobic lipid-like entity and hydrophilic poly(lysine) dendron generations, AmPD 2C18-KK2K4 bearing bigger hydrophilic dendron can package siRNA to form stable, but more ready to disassemble complexes, thereby resulting in more efficient siRNA releasing and better gene silencing effect in comparison with AmPD 2C18-KK2 bearing smaller dendron. Additional studies confirmed that 2C18-KK2K4 can capitalize on the advantages of lipid and peptide dendrimer vectors for effective siRNA delivery. Collectively, our AmPD-based nanocarriers indeed represent a safe and effective siRNA delivery system. Our findings also provide a new perspective on the modulation of self-assembly amphiphilic peptide dendrimers for the functional and adaptive delivery of siRNA therapeutics.

Soluble heat-shock protein 27 in blood serum is a non-invasive prognostic biomarker for ovarian cancer

OBJECTIVES

Ovarian cancer (OC) is the leading cause of death in gynecological oncology, primarily caused by limited prognostic and therapeutic options. The heat shock protein 27 (HSP27) is recognized as a prominent factor in OC, playing a pivotal role in cancer progression machinery such as treatment resistance. Thus, HSP27 may represent an appropriate biomarker for OC diagnosis, prognosis, and therapy response.

MATERIALS & METHODS

Extracellular HSP27 levels were measured by enzyme-linked immunosorbent assay (ELISA) in serum samples of OC patients (n = 242) and compared to a non-malignant control group without any history of cancer (n = 200). Correlations between serum levels of HSP27 and clinical pathological parameters were analyzed by bivariate analysis. Survival analyses were carried out by Kaplan-Meier test.

RESULTS

This study demonstrated that protein levels of HSP27 are comparable in the blood serum of healthy women and OC patients. However, HSP27 levels are significantly correlated with the volume of ascites, residual tumor mass, and age at first diagnosis in OC patients. Notably, elevated levels of HSP27 demonstrate significantly higher overall survival.

CONCLUSION

Taken together, our findings demonstrate that high levels of circulating HSP27 in serum are associated with improved overall survival of OC patients. Even though functionality of secreted HSP27 is still unclear, serum levels of HSP27 represent a putative non-invasive prognostic biomarker candidate for OC progression.

Combined α-methylacyl-CoA racemase inhibition and docetaxel treatment reduce cell proliferation and decrease expression of heat shock protein 27 in androgen receptor-variant-7-positive prostate cancer cells

Background

Disease progression in castrate-resistant prostate cancer (PCa) is most commonly driven by the reactivation of androgen receptor (AR) signaling and involves AR splice variants including ARV7.

Materials and methods

We used the ARV7-positive PCa cell line, 22Rv1, to study the relationship of the PCa marker α-methylacyl-CoA racemase (AMACR), AR, and ARV7 in PCa.

Results

Docetaxel addition but not AMACR inhibition decreased the proliferation of 22Rv1 cells. The combination of AMACR inhibition and docetaxel treatment resulted in a maximum reduction of cell proliferation. The Western blotting analysis revealed that both AR and ARV7 expression were significantly decreased with the use of charcoal-stripped serum following AMACR inhibition and docetaxel treatment. AMACR inhibition and docetaxel treatment in the charcoal-stripped serum condition reduced the proliferation of 22Rv1, possibly via the downregulation of the heat shock protein 27.

Conclusion

Using cell proliferation and Western blot analysis, we demonstrated that AMACR inhibition and docetaxel treatment, under androgen deprivation conditions, significantly reduced the proliferation of ARV7 positive cancer cells and decreased the levels of AR and ARV7 expression, possibly via downregulation of heat shock protein 27.

Downregulation of miR-541 induced by heat stress contributes to malignant transformation of human bronchial epithelial cells via HSP27

Environmental factors are one of the important factors affecting the occurrence of lung cancer. However, few studies have been done on the relationship between hot environment and lung cancer. In the present study, we demonstrated that heat stress leads to anchorage-independent proliferation, mitochondrial apoptosis, and autophagy of Beas-2B cells, which are normal lung bronchial epithelial cells. Heat shock protein 27 (HSP27) promoted heat stress-induced anchorage-independent proliferation and autophagy, but suppressed mitochondrial apoptosis, indicating that HSP27 might act as an oncogene in the malignant transformation of lung epithelial cells. We also showed that HSP27 promoted autophagy of these cells under heat stress via autophagy related 7 (ATG7) and ETS Transcription Factor ELK1 (ELK1), a transcription factor of ATG7, under heat stress. In addition, we showed that HSP27 translation could be repressed by microRNA miR-541, and the biological effects of miR-541 were the opposite to HSP27, suggesting that HSP27 is a downstream target of miR-541. In this study, we characterized a new mechanism whereby HSP27 promotes cell transformation during the onset of lung cancer. Our studies provide new insights into the molecular mechanisms underlying the lung carcinogenic effect of heat exposure. Specifically, heat stress promotes translation of HSP27 by inhibiting miR-541 accumulation, ultimately resulting in activation of autophagy, inhibition of mitochondrial apoptotic pathway and malignant transformation of Human Bronchial Epithelial Cells. This study identifies miR-541 as a potential prognostic biomarker or therapeutic target to improve theory of environmental carcinogenesis.

Self-assembly of amphiphilic phospholipid peptide dendrimer-based nanovectors for effective delivery of siRNA therapeutics in prostate cancer therapy

RNA interference (RNAi) holds great promise for therapeutic applications. However, safe and successful clinical translation essentially requires further advancement of developing efficient delivery systems. Herein, we report that amphiphilic phospholipid peptide dendrimers (AmPPDs) could mediated effective delivery of siRNA targeting Hsp27 for treating castration-resistant prostate cancer (CRPC). AmPPDs bears natural lipid derivative DSPE as the hydrophobic tail and different dendritic l-lysine as the hydrophilic head, capable of compacting siRNA into nanoparticles to protect it from enzymatic degradation. Interestingly, DSPE-KK₂, AmPPD bearing smaller hydrophilic dendron, promoting more efficient intracellular uptake and endosome release of the so-formed siRNA complexes, as well as better siRNA releasing ability, ultimately resulting in more potent gene silencing and anticancer effects both in vitro and in vivo. Such outstanding performance of DSPE-KK₂ in siRNA delivery may attribute to its optimal balance between the hydrophobic tail and hydrophilic dendritic portion. Our findings provide guidance for the development of safe and effective dendrimer-based siRNA delivery system, thus bringing new hope for combating various diseases.

Ivermectin inhibits HSP27 and potentiates efficacy of oncogene targeting in tumor models

HSP27 is highly expressed in, and supports oncogene addiction of, many cancers. HSP27 phosphorylation is a limiting step for activation of this protein and a target for inhibition, but its highly disordered structure challenges rational structure-guided drug discovery. We performed multistep biochemical, structural, and computational experiments to define a spherical 24-monomer complex composed of 12 HSP27 dimers with a phosphorylation pocket flanked by serine residues between their N-terminal domains. Ivermectin directly binds this pocket to inhibit MAPKAP2-mediated HSP27 phosphorylation and depolymerization, thereby blocking HSP27-regulated survival signaling and client-oncoprotein interactions. Ivermectin potentiated activity of anti-androgen receptor and anti-EGFR drugs in prostate and EGFR/HER2-driven tumor models, respectively, identifying a repurposing approach for cotargeting stress-adaptive responses to overcome resistance to inhibitors of oncogenic pathway signaling.

Chaperoning STAT3/5 by Heat Shock Proteins: Interest of Their Targeting in Cancer Therapy

While cells from multicellular organisms are dependent upon exogenous signals for their survival, growth, and proliferation, commitment to a specific cell fate requires the correct folding and maturation of proteins, as well as the degradation of misfolded or aggregated proteins within the cell. This general control of protein quality involves the expression and the activity of molecular chaperones such as heat shock proteins (HSPs). HSPs, through their interaction with the STAT3/STAT5 transcription factor pathway, can be crucial both for the tumorigenic properties of cancer cells (cell proliferation, survival) and for the microenvironmental immune cell compartment (differentiation, activation, cytokine secretion) that contributes to immunosuppression, which, in turn, potentially promotes tumor progression. Understanding the contribution of chaperones such as HSP27, HSP70, HSP90, and HSP110 to the STAT3/5 signaling pathway has raised the possibility of targeting such HSPs to specifically restrain STAT3/5 oncogenic functions. In this review, we present how HSPs control STAT3 and STAT5 activation, and vice versa, how the STAT signaling pathways modulate HSP expression. We also discuss whether targeting HSPs is a valid therapeutic option and which HSP would be the best candidate for such a strategy.

Contribution of the unfolded protein response to breast and prostate tissue homeostasis and its significance to cancer endocrine response

Resistant breast and prostate cancers remain a major clinical problem, new therapeutic approaches and better predictors of therapeutic response are clearly needed. Because of the involvement of the unfolded protein response (UPR) in cell proliferation and apoptosis evasion, an increasing number of publications support the hypothesis that impairments in this network trigger and/or exacerbate cancer. Moreover, UPR activation could contribute to the development of drug resistance phenotypes in both breast and prostate cancers. Therefore, targeting this pathway has recently emerged as a promising strategy in anticancer therapy. This review addresses the contribution of UPR to breast and prostate tissues homeostasis and its significance to cancer endocrine response with focus on the current progress on UPR research related to cancer biology, detection, prognosis and treatment.

The Multiple Roles and Therapeutic Potential of Molecular Chaperones in Prostate Cancer

Prostate cancer (PCa) is one of the most common cancer types in men worldwide. Heat shock proteins (HSPs) are molecular chaperones that are widely implicated in the pathogenesis, diagnosis, prognosis, and treatment of many cancers. The role of HSPs in PCa is complex and their expression has been linked to the progression and aggressiveness of the tumor. Prominent chaperones, including HSP90 and HSP70, are involved in the folding and trafficking of critical cancer-related proteins. Other members of HSPs, including HSP27 and HSP60, have been considered as promising biomarkers, similar to prostate-specific membrane antigen (PSMA), for PCa screening in order to evaluate and monitor the progression or recurrence of the disease. Moreover, expression level of chaperones like clusterin has been shown to correlate directly with the prostate tumor grade. Hence, targeting HSPs in PCa has been suggested as a promising strategy for cancer therapy. In the current review, we discuss the functions as well as the role of HSPs in PCa progression and further evaluate the approach of inhibiting HSPs as a cancer treatment strategy.

Targeting Heat Shock Protein 27 in Cancer: A Druggable Target for Cancer Treatment?

Heat shock protein 27 (HSP27), induced by heat shock, environmental, and pathophysiological stressors, is a multi-functional protein that acts as a protein chaperone and an antioxidant. HSP27 plays a significant role in the inhibition of apoptosis and actin cytoskeletal remodeling. HSP27 is upregulated in many cancers and is associated with a poor prognosis, as well as treatment resistance, whereby cells are protected from therapeutic agents that normally induce apoptosis. This review highlights the most recent findings and role of HSP27 in cancer, as well as the strategies for using HSP27 inhibitors for therapeutic purposes.

A Randomized, Double-Blinded, Phase II Trial of Carboplatin and Pemetrexed with or without Apatorsen (OGX-427) in Patients with Previously Untreated Stage IV Non-Squamous-Non-Small-Cell Lung Cancer: The SPRUCE Trial

BACKGROUND

This randomized, double-blinded, phase II trial evaluated the efficacy of carboplatin and pemetrexed plus either apatorsen, an antisense oligonucleotide targeting heat shock protein (Hsp) 27 mRNA, or placebo in patients with previously untreated metastatic nonsquamous non-small cell lung cancer (NSCLC).

METHODS

Patients were randomized 1:1 to Arm A (carboplatin/pemetrexed plus apatorsen) or Arm B (carboplatin/pemetrexed plus placebo). Treatment was administered in 21-day cycles, with restaging every two cycles, until progression or intolerable toxicity. Serum Hsp27 levels were analyzed at baseline and during treatment. The primary endpoint was progression-free survival (PFS); secondary endpoints included overall survival (OS), objective response rate, and toxicity.

RESULTS

The trial enrolled 155 patients (median age 66 years; 44% Eastern Cooperative Oncology Group performance status 0). Toxicities were similar in the 2 treatment arms; cytopenias, nausea, vomiting, and fatigue were the most frequent treatment-related adverse events. Median PFS and OS were 6.0 and 10.8 months, respectively, for Arm A, and 4.9 and 11.8 months for Arm B (differences not statistically significant). Overall response rates were 27% for Arm A and 32% for Arm B. Sixteen patients (12%) had high serum levels of Hsp27 at baseline. In this small group, patients who received apatorsen had median PFS of 10.8 months, and those who received placebo had median PFS 4.8 months.

CONCLUSION

The addition of apatorsen to carboplatin and pemetrexed was well tolerated but did not improve outcomes in patients with metastatic nonsquamous NSCLC cancer in the first-line setting.

IMPLICATIONS FOR PRACTICE

This randomized, double-blinded, phase II trial evaluated the efficacy of carboplatin and pemetrexed plus either apatorsen, an antisense oligonucleotide targeting heat shock protein 27 mRNA, or placebo in patients with previously untreated metastatic nonsquamous non-small cell lung cancer (NSCLC). The addition of apatorsen to carboplatin and pemetrexed was well tolerated but did not improve outcomes in patients with metastatic nonsquamous NSCLC cancer in the first-line setting.

Evolution from Covalent to Self-Assembled PAMAM-Based Dendrimers as Nanovectors for siRNA Delivery in Cancer by Coupled In Silico-Experimental Studies. Part I: Covalent siRNA Nanocarriers

Small interfering RNAs (siRNAs) represent a new approach towards the inhibition of gene expression; as such, they have rapidly emerged as promising therapeutics for a plethora of important human pathologies including cancer, cardiovascular diseases, and other disorders of a genetic etiology. However, the clinical translation of RNA interference (RNAi) requires safe and efficient vectors for siRNA delivery into cells. Dendrimers are attractive nanovectors to serve this purpose, as they present a unique, well-defined architecture and exhibit cooperative and multivalent effects at the nanoscale. This short review presents a brief introduction to RNAi-based therapeutics, the advantages offered by dendrimers as siRNA nanocarriers, and the remarkable results we achieved with bio-inspired, structurally flexible covalent dendrimers. In the companion paper, we next report our recent efforts in designing, characterizing and testing a series of self-assembled amphiphilic dendrimers and their related structural alterations to achieve unprecedented efficient siRNA delivery both in vitro and in vivo.

Evolution from Covalent to Self-Assembled PAMAM-Based Dendrimers as Nanovectors for siRNA Delivery in Cancer by Coupled in Silico-Experimental Studies. Part II: Self-Assembled siRNA Nanocarriers

In part I of this review, the authors showed how poly(amidoamine) (PAMAM)-based dendrimers can be considered as promising delivering platforms for siRNA therapeutics. This is by virtue of their precise and unique multivalent molecular architecture, characterized by uniform branching units and a plethora of surface groups amenable to effective siRNA binding and delivery to e.g., cancer cells. However, the successful clinical translation of dendrimer-based nanovectors requires considerable amounts of good manufacturing practice (GMP) compounds in order to conform to the guidelines recommended by the relevant authorizing agencies. Large-scale GMP-standard high-generation dendrimer production is technically very challenging. Therefore, in this second part of the review, the authors present the development of PAMAM-based amphiphilic dendrons, that are able to auto-organize themselves into nanosized micelles which ultimately outperform their covalent dendrimer counterparts in in vitro and in vivo gene silencing.

Stress-induced tunneling nanotubes support treatment adaptation in prostate cancer

Tunneling nanotubes (TNTs) are actin-based membranous structures bridging distant cells for intercellular communication. We define roles for TNTs in stress adaptation and treatment resistance in prostate cancer (PCa). Androgen receptor (AR) blockade and metabolic stress induce TNTs, but not in normal prostatic epithelial or osteoblast cells. Co-culture assays reveal enhanced TNT formation between stressed and unstressed PCa cells as well as from stressed PCa to osteoblasts. Stress-induced chaperones clusterin and YB-1 localize within TNTs, are transported bi-directionally via TNTs and facilitate TNT formation in PI3K/AKT and Eps8-dependent manner. AR variants, induced by AR antagonism to mediate resistance to AR pathway inhibition, also enhance TNT production and rescue loss of clusterin- or YB-1-repressed TNT formation. TNT disruption sensitizes PCa to treatment-induced cell death. These data define a mechanistic network involving stress induction of chaperone and AR variants, PI3K/AKT signaling, actin remodeling and TNT-mediated intercellular communication that confer stress adaptative cell survival.

Molecular pathways in cancer response to photodynamic therapy

This minireview describes the complexity of the molecular mechanisms involved in the tumor response to photodynamic treatment (PDT). Different aspects of reactive oxygen (ROS) and nitrogen species (RNS) induced by PDT will be examined. In particular, we will discuss the effect of ROS and RNS on cell compartments and the main mechanisms of cell death induced by the treatment. Moreover, we will also examine host defense mechanisms as well as resistance to PDT.

The Hippo Pathway in Prostate Cancer

Despite recent efforts, prostate cancer (PCa) remains one of the most common cancers in men. Currently, there is no effective treatment for castration-resistant prostate cancer (CRPC). There is, therefore, an urgent need to identify new therapeutic targets. The Hippo pathway and its downstream effectors-the transcriptional co-activators, Yes-associated protein (YAP) and its paralog, transcriptional co-activator with PDZ-binding motif (TAZ)-are foremost regulators of stem cells and cancer biology. Defective Hippo pathway signaling and YAP/TAZ hyperactivation are common across various cancers. Here, we draw on insights learned from other types of cancers and review the latest advances linking the Hippo pathway and YAP/TAZ to PCa onset and progression. We examine the regulatory interaction between Hippo-YAP/TAZ and the androgen receptor (AR), as main regulators of PCa development, and how uncontrolled expression of YAP/TAZ drives castration resistance by inducing cellular stemness. Finally, we survey the potential therapeutic targeting of the Hippo pathway and YAP/TAZ to overcome PCa.

Hsp-27 and NF-κB pathway is associated with AR/AR-V7 expression in prostate cancer cells

In the present study, NF-κB inhibitor BAY 11-7082 and/or Hsp-27 inhibitor KRIBB-3 agents were used to investigate the molecular mechanisms mediating androgen receptor expression on prostate cancer cell lines. The decrease observed in androgen receptor and p65 expressions, particularly at 48 h, in parallel with the decrease in the phosphorylation of the p-IKK α/β and p-Hsp-27 proteins in the LNCaP cells, indicated that androgen receptor inactivation occurred after the inhibition of the NF-κB and Hsp-27. In 22Rv1 cells, androgen receptor variant-7 was also observed to be decreased in the combined dose of 48 h. The association of this decrease with the decrease in androgen receptor and p65 expressions is a supportive result for the role of NF-κB signaling in the formation of androgen receptor variant. In androgen receptor variant-7 siRNA treatment in 22Rv1 cell lines, decrease of expression of androgen receptor variant-7 as well as decrease of expression of androgen receptor and p65 were observed. The decrease statistically significant in androgen receptor and p65 expressions was even greater when siRNA treatment was followed with low dose and time (6 h) combined treatment after transfection. We also showed that increased Noxa and decreased Bcl-2 protein level, indicated that apoptotic induction after this combination. In conclusion, inhibition of NF-κB and Hsp-27 is also important, along with therapies for androgen receptor variant-7 inhibition.

A Dual Targeting Dendrimer-Mediated siRNA Delivery System for Effective Gene Silencing in Cancer Therapy

Small interfering RNA (siRNA) is emerging as a novel therapeutic for treating various diseases, provided a safe and efficient delivery is available. In particular, specific delivery to target cells is critical for achieving high therapeutic efficacy while reducing toxicity. Amphiphilic dendrimers are emerging as novel promising carriers for siRNA delivery by virtue of the combined multivalent cooperativity of dendrimers with the self-assembling property of lipid vectors. Here, we report a ballistic approach for targeted siRNA delivery to cancer cells using an amphiphilic dendrimer equipped with a dual targeting peptide bearing an RGDK warhead. According to the molecular design, the amphiphilic dendrimer was expected to deliver siRNA effectively, while the aim of the targeting peptide was to home in on tumors via interaction of its warhead with integrin and the neuropilin-1 receptor on cancer cells. Coating the positively charged siRNA/dendrimer delivery complex with the negatively charged segment of the targeting peptide via electrostatic interactions led to small and stable nanoparticles which were able to protect siRNA from degradation while maintaining the accessibility of RGDK for targeting cancer cells and preserving the ability of the siRNA to escape from endosomes. The targeted system had enhanced siRNA delivery, stronger gene silencing, and more potent anticancer activity compared to nontargeted or covalent dendrimer-based systems. In addition, neither acute toxicity nor induced inflammation was observed. Consequently, this delivery system constitutes a promising nonviral vector for targeted delivery and can be further developed to provide RNAi-based personalized medicine against cancer. Our study also gives new perspectives on the use of nanotechnology based on self-assembling dendrimers in various biomedical applications.

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.

A randomized phase 2 study of a HSP27 targeting antisense, apatorsen with prednisone versus prednisone alone, in patients with metastatic castration resistant prostate cancer

Purpose Heat shock protein 27 (Hsp27) is implicated in prostate cancer progression. Apatorsen is a second generation phosphorothioate antisense inhibitor of Hsp27 expression. We evaluated apatorsen in patients with metastatic castration resistant prostate cancer (mCRPC). Experimental design Eligible patients were randomized 1:1 to receive intravenous apatorsen (3 loading doses of 600 mg within 5-9 days followed by weekly doses of 1000 mg) with oral prednisone 5 mg twice daily or prednisone alone. The primary endpoint was disease progression at 12 weeks. Crossover from prednisone alone was allowed after radiographic progression. Results 74 patients received apatorsen + prednisone (n = 36) or prednisone alone (n = 38). Twenty-five patients crossed-over to receive apatorsen + prednisone. Apatorsen treated patients received a median of 19 infusions. 50% of apatorsen + prednisone patients (95% CI: 32.9%, 67.1%) compared with 42% of prednisone patients (95% CI: 26.3%, 59.2%) did not have disease progression at week 12 (P = 0.33). A PSA decline of ≥50% was observed in 47% of apatorsen + prednisone and 24% of prednisone patients (P = 0.04), with a median duration of response of 24.1 weeks (95% CI: 12.0, 52) and 14.0 weeks (95% CI: 4.0, 44.4), respectively. A PSA decline of ≥50% was observed in 5 patients (20%) that received cross-over apatorsen. Infusion reactions were the most commonly reported adverse event occurring in 77% of apatorsen-treated patients. Conclusions Apatorsen + prednisone did not change the proportion of CRPC patients without disease progression at 12 weeks compared to prednisone but was associated with significant PSA declines. Further evaluation of Hsp27 targeting in prostate cancer is warranted.

CYP17A1-independent production of the neurosteroid-derived 5α-pregnan-3β,6α-diol-20-one in androgen-responsive prostate cancer cell lines under serum starvation and inhibition by Abiraterone

CYP17A1-independent intratumoral steroid hormone synthesis is regarded as one possible explanation for resistance to treatment with the CYP17-inhibitor Abiraterone (Abi). The aim of our study was therefore to investigate the steroid metabolism of prostate cancer cells under serum starvation and the effects of Abi treatment. We assessed steroid metabolism in a panel of prostate cancer cells under serum starvation by radioactivity detector-coupled HPLC and HPLC-ESI-ToF-mass spectrometry after treatment with pregnenolone, progesterone and allopregnanolone. We further evaluated the effects of Abi on steroid metabolism of testosterone, dihydrotestosterone (DHT) and dehydroepiandrosterone (DHEA) by enzyme immunoassays (EIAs). Androgen-responsive cell lines metabolized pregnenolone primarily to mitogenic steroid 5α-pregnan-3β,6α-diol-20-one under serum starvation. Co-administration of Abi lead to detectable concentrations of the Abi metabolite Δ⁴-Abi (D4A), known to inhibit enzymes other than CYP17A1 in steroid metabolism. In addition, co-administration of Abi abrogated pregnenolone metabolism and resulted in a CYP17A1-independent significant increase of DHEA (13- to >100-fold) and DHT (2.5-fold) in androgen-responsive cells. Our results demonstrate the CYP17A1-independent formation of 5α-pregnan-3β,6α-diol-20-one by androgen-responsive prostate cancer cells under serum starvation and its inhibition by Abi. Its metabolism from pregnenolone suggests a major steroidogenesis shift in these cells, hinting at a neuroendocrine transdifferentiation phenomenon. The marked increase of DHEA levels by Abi resembles the steroidogenic pathways in nervous tissue, in a manner that precludes CYP17A1 activity. To which extent these processes are responsible or involved in the development of resistance to Abi, needs to be further elucidated.

Targeting Hsp27/eIF4E interaction with phenazine compound: a promising alternative for castration-resistant prostate cancer treatment

The actual strategy to improve current therapies in advanced prostate cancer involves targeting genes activated by androgen withdrawal, either to delay or prevent the emergence of the castration-refractory phenotype. However, these genes are often implicated in several physiological processes, and long-term inhibition of survival proteins might be accompanied with cytotoxic effects. To avoid this problem, an alternative therapeutic strategy relies on the identification and use of compounds that disrupt specific protein-protein interactions involved in androgen withdrawal. Specifically, the interaction of the chaperone protein Hsp27 with the initiation factor eIF4E leads to the protection of protein synthesis initiation process and enhances cell survival during cell stress induced by castration or chemotherapy. Thus, in this work we aimed at i) identifying the interaction site of the Hsp27/eIF4E complex and ii) interfere with the relevant protein/protein association mechanism involved in castration-resistant progression of prostate cancer. By a combination of experimental and modeling techniques, we proved that eIF4E interacts with the C-terminal part of Hsp27, preferentially when Hsp27 is phosphorylated. We also observed that the loss of this interaction increased cell chemo-and hormone-sensitivity. In order to find a potential inhibitor of Hsp27/eIF4E interaction, BRET assays in combination with molecular simulations identified the phenazine derivative 14 as the compound able to efficiently interfere with this protein/protein interaction, thereby inhibiting cell viability and increasing cell death in chemo- and castration-resistant prostate cancer models in vitro and in vivo.

Inactivation of ID4 promotes a CRPC phenotype with constitutive AR activation through FKBP52

Castration-resistant prostate cancer (CRPC) is the emergence of prostate cancer cells that have adapted to the androgen-depleted environment of the prostate. In recent years, targeting multiple chaperones and co-chaperones (e.g., Hsp27, FKBP52) that promote androgen receptor (AR) signaling and/or novel AR regulatory mechanisms have emerged as promising alternative treatments for CRPC. We have shown that inactivation of inhibitor of differentiation 4 (ID4), a dominant-negative helix loop helix protein, promotes de novo steroidogenesis and CRPC with a gene expression signature that resembles constitutive AR activity in castrated mice. In this study, we investigated the underlying mechanism through which loss of ID4 potentiates AR signaling. Proteomic analysis between prostate cancer cell line LNCaP (L+ns) and LNCaP lacking ID4 (L(-)ID4) revealed elevated levels of Hsp27 and FKBP52, suggesting a role for these AR-associated co-chaperones in promoting constitutively active AR signaling in L(-)ID4 cells. Interestingly, protein interaction studies demonstrated a direct interaction between ID4 and the 52-kDa FK506-binding protein (FKBP52) in vitro, but not with AR. An increase in FKBP52-dependent AR transcriptional activity was observed in L(-)ID4 cells. Moreover, pharmacological inhibition of FKBP52-AR signaling, by treatment with MJC13, attenuated the tumor growth, weight, and volume in L(-)ID4 xenografts. Together, our results demonstrate that ID4 selectively regulates AR activity through direct interaction with FKBP52, and its loss, promotes CRPC through FKBP52-mediated AR signaling.

Reliable Entity Subtyping in Non-small Cell Lung Cancer by Matrix-assisted Laser Desorption/Ionization Imaging Mass Spectrometry on Formalin-fixed Paraffin-embedded Tissue Specimens

Histopathological subtyping of non-small cell lung cancer (NSCLC) into adenocarcinoma (ADC), and squamous cell carcinoma (SqCC) is of utmost relevance for treatment stratification. However, current immunohistochemistry (IHC) based typing approaches on biopsies are imperfect, therefore novel analytical methods for reliable subtyping are needed. We analyzed formalin-fixed paraffin-embedded tissue cores of NSCLC by Matrix-assisted laser desorption/ionization (MALDI) imaging on tissue microarrays to identify and validate discriminating MALDI imaging profiles for NSCLC subtyping. 110 ADC and 98 SqCC were used to train a Linear Discriminant Analysis (LDA) model. Results were validated on a separate set of 58 ADC and 60 SqCC. Selected differentially expressed proteins were identified by tandem mass spectrometry and validated by IHC. The LDA classification model incorporated 339 m/z values. In the validation cohort, in 117 cases (99.1%) MALDI classification on tissue cores was in accordance with the pathological diagnosis made on resection specimen. Overall, three cases in the combined cohorts were discordant, after reevaluation two were initially misclassified by pathology whereas one was classified incorrectly by MALDI. Identification of differentially expressed peptides detected well-known IHC discriminators (CK5, CK7), but also less well known differentially expressed proteins (CK15, HSP27). In conclusion, MALDI imaging on NSCLC tissue cores as small biopsy equivalents is capable to discriminate lung ADC and SqCC with a very high accuracy. In addition, replacing multislide IHC by an one-slide MALDI approach may also save tissue for subsequent predictive molecular testing. We therefore advocate to pursue routine diagnostic implementation strategies for MALDI imaging in solid tumor typing.

Heat shock protein 27 is a potential indicator for response to YangZheng XiaoJi and chemotherapy agents in cancer cells

Heat shock protein 27 (HSP27) is a member of the heat shock protein family which has been linked to tumour progression and, most interestingly, to chemotherapy resistance in cancer patients. The present study examined the potential interplay between HSP27 and YangZheng XiaoJi, a traditional Chinese medicine used in cancer treatment. A range of cell lines from different tumour types including pancreatic, lung, gastric, colorectal, breast, prostate and ovarian cancer (both wild-type and resistant) were used. Levels and activation of HSP27 and its potential associated signalling pathways were evaluated by protein array and western blotting. Knockdown of HSP27 in cancer cells was achieved using siRNA. Localisation and co-localisation of HSP27 and other proteins were carried out by immunofluorescence. Cell growth and migration were evaluated in their response to a range of chemotherapeutic agents. The present study first identified, by way of protein array, that YangZheng XiaoJi was able to inhibit the phosphorylation of HSP27 protein in cancer cells. We further demonstrated that HSP27, which is co-localised with caspase-9, can be blocked from localising in focal adhesions and co-localising with caspase-9 by YangZheng XiaoJi. The study also demonstrated that YangZheng XiaoJi was able to sensitise cancer cells including those cells that were resistant to chemotherapy, to chemotherapeutic agents. Finally, knocking down HSP27 markedly reduced the migration of cancer cells and increased the sensitivity of cancer cells to the inhibitory effect on cellular migration by YangZheng XiaoJi. YangZheng XiaoJi can act as an agent in first sensitising cancer cells to chemotherapy and secondly to overcome, to some degree, chemoresistance when used in an appropriate fashion in patients who have active HSP27.

Prostate cancer and the unfolded protein response

The endoplasmic reticulum (ER) is an essential organelle that contributes to several key cellular functions, including lipogenesis, gluconeogenesis, calcium storage, and organelle biogenesis. The ER also serves as the major site for protein folding and trafficking, especially in specialized secretory cells. Accumulation of misfolded proteins and failure of ER adaptive capacity activates the unfolded protein response (UPR) which has been implicated in several chronic diseases, including cancer. A number of recent studies have implicated UPR in prostate cancer (PCa) and greatly expanded our understanding of this key stress signaling pathway and its regulation in PCa. Here we summarize these developments and discuss their potential therapeutic implications.

Dendrimer Nanovectors for SiRNA Delivery

Small interfering RNA (SiRNA) delivery remains a major challenge in RNAi-based therapy. Dendrimers are emerging as appealing nonviral vectors for SiRNA delivery thanks to their well-defined architecture and their unique cooperativity and multivalency confined within a nanostructure. We have recently demonstrated that structurally flexible poly(amidoamine) (PAMAM) dendrimers are safe and effective nanovectors for SiRNA delivery in various disease models in vitro and in vivo. The present chapter showcases these dendrimers can package different SiRNA molecules into stable and nanosized particles, which protect SiRNA from degradation and promote cellular uptake of SiRNA, resulting in potent gene silencing at both mRNA and protein level in the prostate cancer cell model. Our results demonstrate this set of flexible PAMAM dendrimers are indeed safe and effective nonviral vectors for SiRNA delivery and hold great promise for further applications in functional genomics and RNAi-based therapies.