The role of HSP90 molecular chaperones in hepatocellular carcinoma

AFP-HSP90 mediated MYC/MET activation promotes tumor progression in hepatocellular carcinoma and gastric cancers

Alpha-fetoprotein (AFP) elevation is a well-known biomarker in various diseases, particularly in the diagnosis of hepatocellular carcinoma (HCC). Intracellular AFP has been previously implicated in promoting tumorigenesis. In this study, we discovered that AFP enhances the stability of oncoproteins c-MYC and c-MET, thereby facilitating the progression of liver and gastric tumors. Our findings suggest that AFP acts by stabilizing these oncoproteins, which are clients of heat shock protein 90 (HSP90), and prevents their degradation through ubiquitination. Intriguingly, we identified AFP as a novel co-chaperone of HSP90, demonstrating its ability to regulate the stabilization of HSP90 client proteins. Furthermore, our results indicate that inhibiting AFP or HSP90 enhances the cytotoxicity of chemotherapeutic agents in AFP-producing HCC and gastric cancer cells. These findings have significant implications for the development of therapeutic strategies targeting AFP-producing tumors, as the AFP-HSP90-mediated activation of c-MYC and c-MET provides new insights into potential treatment approaches. In summary, this study sheds light on the role of AFP in promoting tumor progression by stabilizing oncoproteins through its interaction with HSP90. The identification of this mechanism opens up new avenues for therapeutic interventions in AFP-producing tumors.

Mesenchymal stem cell-derived exosomes ameliorate hypoxic pulmonary hypertension by inhibiting the Hsp90aa1/ERK/pERK pathway

Hypoxic pulmonary hypertension (HPH) is a serious and life-threatening chronic cardiopulmonary disease characterized by progressive elevation of pulmonary artery pressure and pulmonary vascular remodeling. Mesenchymal stem cell- derived exosomes (MSC-Exos) can relieve HPH by reversing pulmonary vascular remodeling. The HPH model was established in healthy male Sprague-Dawley (SD) rats aged 6 to 8 weeks. The rats were placed in a room with oxygen concentration of (10 ± 1) % for 8 hours a day over 28 days, were then injected intravenously with MSC-Exos (100 ug protein/kg) or equal-volume phosphate buffer saline (PBS) once a day over 1 week. Right ventricular systolic pressure (RVSP), right ventricular hypertrophy index (RVHI) and pulmonary vascular remodeling were observed after anesthesia. In addition, platelet-derived growth factor BB (PDGF-BB) was used to stimulate rat pulmonary artery smooth muscle cells (PASMCs) to construct HPH pathological cell models. The results showed that MSC-Exos could not only reduce the elevation of RVSP, right ventricular hypertrophy and the degree of pulmonary vascular remodeling in HPH rats, but also reduce the proliferation, migration and apoptosis resistance of PASMCs. Finally, GSE53408 and GSE113439 datasets were analyzed and showed that the expression of Hsp90aa1 and pERK/ERK were significantly increased in HPH, also could be inhibited by MSC-Exos. Meanwhile, inhibition of Hsp90aa1 also reduced PASMCs migration and pERK/ERK protein level. In conclusion, MSC-Exos alleviated HPH by suppressing PASMCs proliferation, migration and apoptosis resistance through inhibiting the Hsp90aa1/ERK/pERK pathway.

GCNT3 Promotes Hepatocellular Carcinoma Progression and EMT by Activating the PI3K/AKT Pathway

Primary liver cancer, specifically hepatocellular carcinoma (HCC), is a major global health concern. GCNT3 has been identified as an oncogene in various human malignancies. This investigation aimed to discover the GCNT3 function in HCC. The present study employed integrated bioinformatics analyses to assess the expression pattern, prognostic implications, and putative function of GCNT3 in HCC. Transwell flow cytometry, CCK-8, and wound healing assays were performed to examine HCC cell growth, cell cycle, apoptosis, invasion, and migration. In addition, the epithelial-mesenchymal transition (EMT) markers and PI3K/AKT mechanism markers were examined via western blot analysis to elucidate the underlying mechanisms. In HCC, GCNT3 was significantly overexpressed, which was connected with enhanced tumor aggressiveness and an unfavorable prognosis of individuals. In vitro experiments demonstrated that elevated levels of GCNT3 promoted cell growth, migration, cell cycle development, and invasion, in addition to EMT, while suppressing apoptosis. Conversely, knockdown of GCNT3 exerted the opposite effects. GCNT3 overexpression increased PI3K/AKT phosphorylation in HCC cells, and LY294002 counteracted the impacts of upregulated GCNT3 on cell cycle, migration, invasion, proliferation, and EMT in HCC. The investigation showed that GCNT3 may enhance HCC progression and EMT by stimulating PI3K/AKT mechanism.

The Role of HSP90 and TRAP1 Targets on Treatment in Hepatocellular Carcinoma

Hepatocellular Carcinoma (HCC) is the predominant form of liver cancer and arises due to dysregulation of the cell cycle control machinery. Heat Shock Protein 90 (HSP90) and mitochondrial HSP90, also referred to as TRAP1 are important critical chaperone target receptors for early diagnosis and targeting HCC. Both HSP90 and TRAP1 expression was found to be higher in HCC patients. Hence, the importance of HSP90 and TRAP1 inhibitors mechanism and mitochondrial targeted delivery of those inhibitors function is widely studied. This review also focuses on importance of protein-protein interactions of HSP90 and TRAP1 targets and association of its interacting proteins in various pathways of HCC. To further elucidate the mechanism, systems biology approaches and computational biology approach studies are well explored in the association of inhibition of herbal plant molecules with HSP90 and its mitochondrial type in HCC.

Scutellaria baicalensis Induces Cell Apoptosis and Elicits Mesenchymal-Epithelial Transition to Alleviate Metastatic Hepatocellular Carcinoma via Modulating HSP90β

Hepatocellular carcinoma is one of the most common malignant tumors in the world and shows strong metastatic potential. Current medicine for hepatocellular carcinoma therapy is invalid, while Scutellaria baicalensis Georgi exhibits the pharmaceutical potential to treat liver diseases and liver cancer. Herein, we verified the inhibitory properties and the pivotal molecules regimented by Scutellaria baicalensis on advanced hepatocellular carcinoma. At first, the viability of SK-Hep-1 cells was significantly reduced under treatment of Scutellaria baicalensis extract in a dose-dependent manner without affecting the growth of normal hepatocyte. Scutellaria baicalensis extract application could remarkably cause apoptosis of SK-Hep-1 cells through p53/cytochrome C/poly-ADP ribose polymerase cascades and arrest the cell cycle at the G1/S phase by downregulating cyclin-dependent kinases. Meanwhile, administration of Scutellaria baicalensis extract remarkably attenuated the migration capability as well as suppressed matrix metalloproteinase activity of advanced hepatocellular carcinoma cells. The proteome profiles and network analysis particularly implied that exposure to Scutellaria baicalensis extract downregulated the expression of HSP90β, and the clinical stage of hepatocellular carcinoma is also positively correlated with the HSP90β level. Combined treatment of Scutellaria baicalensis extract and HSP90β siRNAs could markedly enhance the ubiquitination activity and the degradation of vimentin to subsequently inhibit the metastatic property of SK-Hep-1 cells. Moreover, application of Scutellaria baicalensis extract and HSP90β siRNAs depleted phosphorylation of AKT, which stimulated the expression of p53 and consecutively triggered cell apoptosis. These findings suggest that HSP90β may be a prospective target for the effective therapy of advanced hepatocellular carcinoma via accelerating apoptosis of hepatocellular carcinoma cells and eliciting mesenchymal-epithelial transition with the administration of Scutellaria baicalensis extract.

Decoding the roles of heat shock proteins in liver cancer

Hepatocellular carcinoma (HCC) is one of the most common gastrointestinal malignancies, characterized by insidious onset and high propensity for metastasis and recurrence. Apart from surgical resection, there are no effective curative methods for HCC in recent years, due to resistance to radiotherapy and chemotherapy. Heat shock proteins (HSP) play a crucial role in maintaining cellular homeostasis and normal organism development as molecular chaperones for intracellular proteins. Both basic research and clinical data have shown that HSPs are crucial participants in the HCC microenvironment, as well as the occurrence, development, metastasis, and resistance to radiotherapy and chemotherapy in various malignancies, particularly liver cancer. This review aims to discuss the molecular mechanisms and potential clinical value of HSPs in HCC, which may provide new insights for HSP-based therapeutic interventions for HCC.

The development of cancers research based on mitochondrial heat shock protein 90

Mitochondrial heat shock protein 90 (mtHsp90), including Tumor necrosis factor receptor-associated protein 1 (TRAP1) and Hsp90 translocated from cytoplasm, modulating cellular metabolism and signaling pathways by altering the conformation, activity, and stability of numerous client proteins, and is highly expressed in tumors. mtHsp90 inhibition results in the destabilization and eventual degradation of its client proteins, leading to interference with various tumor-related pathways and efficient control of cancer cell development. Among these compounds, gamitrinib, a specific mtHsp90 inhibitor, has demonstrated its safety and efficacy in several preclinical investigations and is currently undergoing evaluation in clinical trials. This review aims to provide a comprehensive overview of the present knowledge pertaining to mtHsp90, encompassing its structure and function. Moreover, our main emphasis is on the development of mtHsp90 inhibitors for various cancer therapies, to present a thorough overview of the recent pre-clinical and clinical advancements in this field.

HSP90 C-terminal domain inhibition promotes VDAC1 oligomerization via decreasing K274 mono-ubiquitination in Hepatocellular Carcinoma

Voltage-dependent anion-selective channel protein 1 (VDAC1) is the most abundant protein in the mitochondrial outer membrane and plays a crucial role in the control of hepatocellular carcinoma (HCC) progress. Our previous research found that cytosolic molecular chaperone heat shock protein 90 (Hsp90) interacted with VDAC1, but the effect of the C-terminal and N-terminal domains of Hsp90 on the formation of VDAC1 oligomers is unclear. In this study, we focused on the effect of the C-terminal domain of Hsp90 on VDAC1 oligomerization, ubiquitination, and VDAC1 channel activity. We found that Hsp90 C-terminal domain inhibitor Novobiocin promoted VDAC1 oligomerization, release of cytochrome c, and activated mitochondrial apoptosis pathway. Atomic coarse particle modeling simulation revealed C-terminal domain of Hsp90α stabilized VDAC1 monomers. The purified VDAC1 was reconstituted into a planar lipid bilayer, and electrophysiology experiments of patch clamp showed that the Hsp90 C-terminal inhibitor Novobiocin increased VDAC1 channel conductance via promoting VDAC1 oligomerization. The mitochondrial ubiquitination proteomics results showed that VDAC1 K274 mono-ubiquitination was significantly decreased upon Novobiocin treatment. Site-directed mutation of VDAC1 (K274R) weakened Hsp90α-VDAC1 interaction and increased VDAC1 oligomerization. Taken together, our results reveal that Hsp90 C-terminal domain inhibition promotes VDAC1 oligomerization and VDAC1 channel conductance by decreasing VDAC1 K274 mono- ubiquitination, which provides a new perspective for mitochondria-targeted therapy of HCC.

Clinicopathological and prognostic significance of heat shock proteins in hepatocellular carcinoma: a systematic review and meta-analysis

Background

Overexpression of heat shock proteins (HSPs) has been observed in a wide range of human tumors, and there is an increasing evidence demonstrated that HSPs play a key role in tumor progression. Several studies were conducted to explore the clinicopathological characteristics and prognostic value of HSPs in hepatocellular carcinoma (HCC), but the results remain controversial. To address this gap, we conducted a systematic review and meta-analysis.

Methods

The eligible literature was obtained from PubMed, Cochrane library, Web of science, Embase, Chinese National Knowledge Infrastructure and Wan Fang databases. We used the odds ratio (OR) and hazard ratio (HR) as the suitable parameters to assess the clinicopathological features and prognostic value of HSPs in HCC patients.

Results

The meta-analysis results showed that HSPs expression was associated with overall survival (OS) of HCC patients (HR = 1.61, 95%CI = 1.22-2.13, P=0.001, I 2 = 62.7%). In addition, the pooled results suggested that HSPs expression was significantly correlated with tumor differentiation (OR = 1.33, 95%CI = 1.08-1.65, P = 0.907), vascular invasion (OR = 1.31, 95%CI = 1.02-1.69, P = 0.921) and lymphatic metastasis (OR=1.98, 95%CI= 1.70-2.31, P = 0.740). Meanwhile, the subgroup analysis showed a significant correlation between the expression of HSP27 (HR=1.69, 95%CI = 1.24-2.31, P = 0.674) and HSP90α (HR=2.03, 95%CI = 1.73-2.40, P = 0.743) with OS of HCC patients.

Conclusions

Our meta-analysis confirms that HSPs expression is closely associated with a worse prognosis in HCC patients, and may be directly involved in tumor differentiation and distant metastasis. In addition, the subgroup analysis results demonstrate that the expression of HSP27 and HSP90α can be served as potential prognostic predictors of HCC.

Rational design, synthesis and structural characterization of peptides and peptidomimetics to target Hsp90/Cdc37 interaction for treating hepatocellular carcinoma

Heat shock protein 90 (Hsp90) and cell division cycle 37 (Cdc37) work together as a molecular chaperone complex to regulate the activity of a multitude of client protein kinases. These kinases belong to a wide array of intracellular signaling networks that mediate multiple cellular processes including proliferation. As a result, Hsp90 and Cdc37 represent innovative therapeutic targets in various cancers (such as leukemia, multiple myeloma, and hepatocellular carcinoma (HCC)) in which their expression levels are elevated. Conventional small molecule Hsp90 inhibitors act by blocking the conserved adenosine triphosphate (ATP) binding site. However, by targeting less conserved sites in a more specific manner, peptides and peptidomimetics (modified peptides) hold potential as more efficacious and less toxic alternatives to the conventional small molecule inhibitors. Using a rational approach, we herein developed bioactive peptides targeting Hsp90/Cdc37 interaction. A six amino acid linear peptide derived from Cdc37, KTGDEK, was designed to target Hsp90. We used in silico computational docking to first define its mode of interaction, and binding orientation, and then conjugated the peptide with a cell penetrating peptide, TAT, and a fluorescent dye to confirm its ability to colocalize with Hsp90 in HCC cells. Based on the parent linear sequence, we developed a peptidomimetics library of pre-cyclic and cyclic derivatives. These peptidomimetics were evaluated for their binding affinity to Hsp90, and bioactivity in HCC cell lines. Among them, a pre-cyclic peptidomimetic demonstrates high binding affinity and bioactivity in HCC cells, causing reduced cell proliferation that is associated with induction of cell apoptosis, and down-regulation of phosphorylated MEK1/2. Overall, this generalized approach of rational design, structural optimization, and cellular validation of 'drug-like' peptidomimetics against Hsp90/Cdc37 offers a feasible and promising way to design novel therapeutic agents for malignancies and other diseases that are dependent on this molecular chaperone complex.

Comprehensive pan-cancer analysis of PTGES3 and its prognostic role in hepatocellular carcinoma

Introduction

PTGES3, also known as p23, is a molecule chaperone of Hsp90 that is involved in the pathogenesis of malignant tumors. Increasing studies have shown that PTGES3 plays a nonnegligible role in tumor development. However, analysis of PTGES3 in pan-cancer has not been performed yet.

Methods

We explored the role of PTGES3 in 33 types of tumors and depicted the potentialimmune-related pathways among them. Using multiple databases includingTCGA, LinkedOmics, GDSC, and TIMER, we made a comprehensive analysis to explore whether there was an interaction between PTGES3 and prognosis, DNA methylation, copy number variation (CNV), tumor mutational burden (TMB), microsatellite instability (MSI), and tumor immune microenvironment (TME).

Results

Our study revealed that PTGES3 expression level was upregulated in most cancers. PTGES3 was also associated with a positive or negative prognosis in a variety of cancers, which was mainly associated with DNA methylation, CNV, MSI, TMB, andmismatch repair-related genes. High PTGES3 expression was related to the infiltration of Th2 subsets of CD4+ T cells and immune checkpoint-related genes in most cancers, especially in hepatocellular carcinoma (HCC). Enrichment analysis demonstrated that PTGES3 was involved in cellular processes including DNA replication and spliceosome. The relationship between PTGES3 expression and HCC progression was verified at the protein level through immune histochemical analysis.

Conclusions

Our research demonstrated theprognostic predictive value of PTGES3 in a wide range of cancers, which was alsoassociated with the process of tumor immune infiltration. As a result, it suggestedthat PTGES3 was a valuable prognostic biomarker in HCC treatment.

Targeting ACYP1-mediated glycolysis reverses lenvatinib resistance and restricts hepatocellular carcinoma progression

Acylphosphatase 1 (ACYP1), a protein located in the mammalian cell cytoplasm, has been shown to be associated with tumor initiation and progression by functioning as a metabolism-related gene. Here we explored the potential mechanisms by which ACYP1 regulates the development of HCC and participates in the resistance to lenvatinib. ACYP1 can promote the proliferation, invasion, and migration capacities of HCC cells in vitro and in vivo. RNA sequencing reveals that ACYP1 markedly enhances the expression of genes related to aerobic glycolysis, and LDHA is identified as the downstream gene of ACYP1. Overexpression of ACYP1 upregulates LDHA levels, which then increases the malignancy potential of HCC cells. GSEA data analysis reveals the enrichment of differentially expressed genes in the MYC pathway, indicating a positive correlation between MYC and ACYP1 levels. Mechanistically, ACYP1 exerts its tumor-promoting roles by regulating the Warburg effect through activating the MYC/LDHA axis. Mass spectrometry analysis and Co-IP assays confirm that ACYP1 can bind to HSP90. The regulation of c-Myc protein expression and stability by ACYP1 is HSP90 dependent. Importantly, lenvatinib resistance is associated with ACYP1, and targeting ACYP1 remarkably decreases lenvatinib resistance and inhibits progression of HCC tumors with high ACYP1 expression when combined with lenvatinib in vitro and in vivo. These results illustrate that ACYP1 has a direct regulatory role in glycolysis and drives lenvatinib resistance and HCC progression via the ACYP1/HSP90/MYC/LDHA axis. Targeting ACYP1 could synergize with lenvatinib to treat HCC more effectively.

Innovative challenge for the inhibition of hepatocellular carcinoma progression by combined targeting of HSP90 and STAT3/HIF-1α signaling

Hepatocellular carcinoma (HCC) is the third foremost cause of cancer-related deaths. HCC has a very bad prognosis because it is asymptomatic in the early stages, resulting in a late diagnosis, and it is highly resistant to conventional chemotherapy. Such chemotherapies have been proven disappointing because they provide extremely low survival benefits. This study discloses that the STAT3/HIF-1α is an auspicious therapeutic attack site for conceivable repression of HCC development. A site that can be targeted by simultaneous administration of a STAT3 inhibitor in the context of HSP90 inhibition. 17-DMAG binds to HSP90 and constrains its function, resulting in the degradation of HSP90 client proteins HIF-1α and STAT3. Hypoxia recruits STAT3/HIF-1α complex within the VEGF promoter. Additionally, it was acknowledged that STAT3 is an essential mediator of VEGF transcription by direct binding to its promoter. Furthermore, it induces HIF-1α stability and enhances its transcriptional activity. Herein, we revealed that the combination therapy using 17-DMAG and nifuroxazide, a STAT3 inhibitor, repressed the diethylnitrosamine-induced alterations in the structure of the liver. This effect was mediated via decreasing the levels of the HSP90 client proteins HIF-1α and pSTAT3 resulting in the suppression of the STAT3/HIF-1α complex transcriptional activity. To conclude, 17-DMAG/NFXZD combination therapy-induced disruption in the STAT3/HIF-1α loop led to a potential antiangiogenic activity and showed apoptotic potential by inhibiting autophagy and inducing ROS/apoptosis signaling. Additionally, this combination therapy exhibited promising survival prolongation in mice with HCC. Consequently, the use of 17-DMAG/NFXZD renders an inspirational perspective in managing HCC. However, further investigations are compulsory.

Comparative RNA-Sequencing Analysis Reveals High Complexity and Heterogeneity of Transcriptomic and Immune Profiles in Hepatocellular Carcinoma Tumors of Viral (HBV, HCV) and Non-Viral Etiology

Background and Objectives: Hepatocellular carcinoma (HCC), the most common type of primary liver cancer, is the leading cause of cancer-related mortality. It arises and progresses against fibrotic or cirrhotic backgrounds mainly due to infection with hepatitis viruses B (HBV) or C (HCV) or non-viral causes that lead to chronic inflammation and genomic changes. A better understanding of molecular and immune mechanisms in HCC subtypes is needed. Materials and Methods: To identify transcriptional changes in primary HCC tumors with or without hepatitis viral etiology, we analyzed the transcriptomes of 24 patients by next-generation sequencing. Results: We identified common and unique differentially expressed genes for each etiological tumor group and analyzed the expression of SLC, ATP binding cassette, cytochrome 450, cancer testis, and heat shock protein genes. Metascape functional enrichment analysis showed mainly upregulated cell-cycle pathways in HBV and HCV and upregulated cell response to stress in non-viral infection. GeneWalk analysis identified regulator, hub, and moonlighting genes and highlighted CCNB1, ACTN2, BRCA1, IGF1, CDK1, AURKA, AURKB, and TOP2A in the HCV group and HSF1, HSPA1A, HSP90AA1, HSPB1, HSPA5, PTK2, and AURKB in the group without viral infection as hub genes. Immune infiltrate analysis showed that T cell, cytotoxic, and natural killer cell markers were significantly more highly expressed in HCV than in non-viral tumors. Genes associated with monocyte activation had the highest expression levels in HBV, while high expression of genes involved in primary adaptive immune response and complement receptor activity characterized tumors without viral infection. Conclusions: Our comprehensive study underlines the high degree of complexity of immune profiles in the analyzed groups, which adds to the heterogeneous HCC genomic landscape. The biomarkers identified in each HCC group might serve as therapeutic targets.

AHSA1 Promotes Proliferation and EMT by Regulating ERK/CALD1 Axis in Hepatocellular Carcinoma

Simple Summary

Globally, hepatocellular carcinoma is one of the leading causes of cancer-related death. Activator of HSP90 ATPase activity 1(AHSA1) was reported to be involved in regulating the maturation, stability, and degradation of related cancer-promoting proteins. However, the biological function and regulatory mechanism of AHSA1 in hepatocellular carcinoma were unclearly. In this study, we found AHSA1 was upregulated and associated with poor clinical characteristics and prognosis of hepatocellular carcinoma patients. Moreover, AHSA1 promoted proliferation, metastasis, epithelium-mesenchymal transition of hepatocellular carcinoma both in vitro and in vivo by recruiting ERK1/2 and promoting the phosphorylation and inactivation of CALD1. Taken together, our findings provided a mechanistic insight into the role of AHSA1 in hepatocellular carcinoma progression and implied AHSA1 may be a biomarker and therapeutic target for hepatocellular carcinoma patients.

Abstract

Hepatocellular carcinoma (HCC) is one of the major causes of cancer-related death worldwide. AHSA1 as a chaperone of HSP90 promotes the maturation, stability, and degradation of related cancer-promoting proteins. However, the regulatory mechanism and biological function of AHSA1 in HCC are largely unknown. Actually, we found that AHSA1 was significantly upregulated in HCC tissues and cell lines and was notably correlated with the poor clinical characteristics and prognosis of HCC patients in this study. Furthermore, both in vitro and in vivo, gain- and loss-of-function studies demonstrated that AHSA1 promoted the proliferation, invasion, metastasis, and epithelial-mesenchymal transition (EMT) of HCC. Moreover, the mechanistic study indicated that AHSA1 recruited ERK1/2 and promoted the phosphorylation and inactivation of CALD1, while ERK1/2 phosphorylation inhibitor SCH772984 reversed the role of AHSA1 in the proliferation and EMT of HCC. Furthermore, we demonstrated that the knockdown of CALD1 reversed the inhibition of proliferation and EMT by knocking AHSA1 in HCC. We also illustrated a new molecular mechanism associated with AHSA1 in HCC that was independent of HSP90 and MEK1/2. In summary, AHSA1 may play an oncogenic role in HCC by regulating ERK/CALD1 axis and may serve as a novel therapeutic target for HCC.

The Disassociation of the A20/HSP90 Complex via Downregulation of HSP90 Restores the Effect of A20 Enhancing the Sensitivity of Hepatocellular Carcinoma Cells to Molecular Targeted Agents

NF-κB (nuclear factor κB) is a regulator of hepatocellular cancer (HCC)-related inflammation and enhances HCC cells' resistance to antitumor therapies by promoting cell survival and anti-apoptosis processes. In the present work, we demonstrate that A20, a dominant-negative regulator of NF-κB, forms a complex with HSP90 (heat-shock protein 90) and causes the disassociation of the A20/HSP90 complex via downregulation of HSP90. This process restores the antitumor activation of A20. In clinical specimens, the expression level of A20 did not relate with the outcome in patients receiving sorafenib; however, high levels of HSP90 were associated with poor outcomes in these patients. A20 interacted with and formed complexes with HSP90. Knockdown of HSP90 and treatment with an HSP90 inhibitor disassociated the A20/HSP90 complex. Overexpression of A20 alone did not affect HCC cells. Downregulation of HSP90 combined with A20 overexpression restored the effect of A20. Overexpression of A20 repressed the expression of pro-survival and anti-apoptosis-related factors and enhanced HCC cells' sensitivity to sorafenib. These results suggest that interactions with HSP90 could be potential mechanisms of A20 inactivation and disassociation of the A20/HSP90 complex and could serve as a novel strategy for HCC treatment.

Performance of Plasma HSP90α, Serum EBV VCA IgA Antibody and Plasma EBV DNA for the Diagnosis and Prognosis Prediction of Nasopharyngeal Carcinoma

OBJECTIVE

The aim of this study was to evaluate the effectiveness of Epstein-Barr virus (EBV) VCA-IgA antibody, EBV DNA and HSP90α alone or in combinations for the diagnosis and prognostic prediction of nasopharyngeal carcinoma (NPC).

METHODS

A total of 113 treatment-naïve patients with NPC and 40 healthy controls were enrolled. Plasma HSP90α and serum EBV VCA IgA antibody were detected using ELISA, and plasma EBV DNA was quantified using qPCR assay. The effectiveness of plasma HSP90α level, serum EBV VCA IgA antibody and plasma EBV DNA was examined in the diagnosis and prognosis prediction of NPC.

RESULTS

Higher plasma HSP90α, serum EBV VCA IgA antibody and plasma viral load of EBV DNA were detected in NPC patients than in healthy controls (P < 0.001). The plasma HSP90α levels, serum EBV VCA IgA antibody titers and plasma viral load of EBV DNA were significantly greater in NPC patients with stages III and IV than in those with stages I and II (P < 0.001), and significantly lower plasma HSP90α levels, serum EBV VCA IgA antibody titers and plasma viral load of EBV DNA were found in the good prognosis group than in the poor prognosis group post-treatment (P < 0.05). The area under representative operating curves (AUCs) of plasma HSP90α, serum EBV VCA IgA antibody and plasma EBV DNA alone and in combination were 0.884, 0.841, 0.934 and 0.954 for the diagnosis of NPC, respectively. Univariate and multivariate Cox proportional hazards regression analyses identified HSP90α as an independent prognostic factor for NPC.

CONCLUSION

The combination of plasma HSP90α, serum EBV VCA IgA antibody and plasma EBV DNA shows high diagnostic performance for NPC, and plasma HSP90α may be a potential marker for diagnosis and prognosis prediction of NPC.

A Review of Progress in Histone Deacetylase 6 Inhibitors Research: Structural Specificity and Functional Diversity

Histone deacetylases (HDACs) are essential for maintaining homeostasis by catalyzing histone deacetylation. Aberrant expression of HDACs is associated with various human diseases. Although HDAC inhibitors are used as effective chemotherapeutic agents in clinical practice, their applications remain limited due to associated side effects induced by weak isoform selectivity. HDAC6 displays unique structure and cellular localization as well as diverse substrates and exhibits a wider range of biological functions than other isoforms. HDAC6 inhibitors have been effectively used to treat cancers, neurodegenerative diseases, and autoimmune disorders without exerting significant toxic effects. Progress has been made in defining the crystal structures of HDAC6 catalytic domains which has influenced the structure-based drug design of HDAC6 inhibitors. This review summarizes recent literature on HDAC6 inhibitors with particular reference to structural specificity and functional diversity. It may provide up-to-date guidance for the development of HDAC6 inhibitors and perspectives for optimization of therapeutic applications.