Identification of histone deacetylase 1 protein complexes in liver cancer cells

Histone deacetylase complexes: Structure, regulation and function

Histone deacetylases (HDACs) are key epigenetic regulators, and transcriptional complexes with deacetylase function are among the epigenetic corepressor complexes in the nucleus that target the epigenome. HDAC-bearing corepressor complexes such as the Sin3 complex, NuRD complex, CoREST complex, and SMRT/NCoR complex are common in biological systems. These complexes activate the otherwise inactive HDACs in a solitary state. HDAC complexes play vital roles in the regulation of key biological processes such as transcription, replication, and DNA repair. Moreover, deregulated HDAC complex function is implicated in human diseases including cancer. Therapeutic strategies targeting HDAC complexes are being sought actively. Thus, illustration of the nature and composition of HDAC complexes is vital to understanding the molecular basis of their functions under physiologic and pathologic conditions, and for designing targeted therapies. This review presents key aspects of large multiprotein HDAC-bearing complexes including their structure, function, regulatory mechanisms, implication in disease development, and role in therapeutics.

Decoding the Role of O-GlcNAcylation in Hepatocellular Carcinoma

Post-translational modifications (PTMs) influence protein functionality by modulating protein stability, localization, and interactions with other molecules, thereby controlling various cellular processes. Common PTMs include phosphorylation, acetylation, ubiquitination, glycosylation, SUMOylation, methylation, sulfation, and nitrosylation. Among these modifications, O-GlcNAcylation has been shown to play a critical role in cancer development and progression, especially in hepatocellular carcinoma (HCC). This review outlines the role of O-GlcNAcylation in the development and progression of HCC. Moreover, we delve into the underlying mechanisms of O-GlcNAcylation in HCC and highlight compounds that target O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA) to improve treatment outcomes. Understanding the role of O-GlcNAcylation in HCC will offer insights into potential therapeutic strategies targeting OGT and OGA, which could improve treatment for patients with HCC.

Prefoldin Function in Cellular Protein Homeostasis and Human Diseases

Cellular functions are largely performed by proteins. Defects in the production, folding, or removal of proteins from the cell lead to perturbations in cellular functions that can result in pathological conditions for the organism. In cells, molecular chaperones are part of a network of surveillance mechanisms that maintains a functional proteome. Chaperones are involved in the folding of newly synthesized polypeptides and assist in refolding misfolded proteins and guiding proteins for degradation. The present review focuses on the molecular co-chaperone prefoldin. Its canonical function in eukaryotes involves the transfer of newly synthesized polypeptides of cytoskeletal proteins to the tailless complex polypeptide 1 ring complex (TRiC/CCT) chaperonin which assists folding of the polypeptide chain in an energy-dependent manner. The canonical function of prefoldin is well established, but recent research suggests its broader function in the maintenance of protein homeostasis under physiological and pathological conditions. Interestingly, non-canonical functions were identified for the prefoldin complex and also for its individual subunits. We discuss the latest findings on the prefoldin complex and its subunits in the regulation of transcription and proteasome-dependent protein degradation and its role in neurological diseases, cancer, viral infections and rare anomalies.

A comprehensive analysis of prefoldins and their implication in cancer

Prefoldins (PFDNs) are evolutionary conserved co-chaperones, initially discovered in archaea but universally present in eukaryotes. PFDNs are prevalently organized into hetero-hexameric complexes. Although they have been overlooked since their discovery and their functions remain elusive, several reports indicate they act as co-chaperones escorting misfolded or non-native proteins to group II chaperonins. Unlike the eukaryotic PFDNs which interact with cytoskeletal components, the archaeal PFDNs can bind and stabilize a wide range of substrates, possibly due to their great structural diversity. The discovery of the unconventional RPB5 interactor (URI) PFDN-like complex (UPC) suggests that PFDNs have versatile functions and are required for different cellular processes, including an important role in cancer. Here, we summarize their functions across different species. Moreover, a comprehensive analysis of PFDNs genomic alterations across cancer types by using large-scale cancer genomic data indicates that PFDNs are a new class of non-mutated proteins significantly overexpressed in some cancer types.

Pharmacological inhibition of HDAC1/3-interacting proteins induced morphological changes, and hindered the cell proliferation and migration of hepatocellular carcinoma cells

Liver diseases are particularly severe health problems, but the options available for preventing and treating them remain limited. Accumulating evidence has shown that there is altered expression of individual histone deacetylase (HDAC) family members in hepatocellular carcinoma cells. In a previous study, we have identified a set of proteins which interact with histone deacetylase 1 and 3 (HDAC1/3) in hepatocellular carcinoma cell lines HepG2 by proteomic approach. This study was designed to investigate the therapeutic potential and expression of HDAC1/3-interacting genes in a human hepatocellular carcinoma cell line (HepG2). Pharmacological and transcriptional inhibition of HDAC1/3 resulted in the suppression of cancer cell proliferation, change of cell morphology, and downregulation of HDAC1/3 genes in HepG2 cells. The pharmacological inhibition also resulted in inhibition of liver cancer cell migration by wound scratch assay. Taken together, the results from this study show that the upregulation of HDAC1/3 in hepatocellular carcinoma resulted in the overexpression of CNOT1, PFDN2/6, and HMG20B, and that these genes could serve as novel molecular targets in liver cancer.

Histone deacetylase inhibitor induced pVHL-independent degradation of HIF-1α and hierarchical quality control of pVHL via chaperone system

The mortality rate of ovarian cancer is increasing and the role of hypoxia inducible factor-1α (HIF-1α) in tumor progression has been confirmed. von Hippel-Lindau tumor suppressor protein (pVHL) binds HIF-1α and mediates proteasome degradation of HIF-1α. Besides, histone deacetylase inhibitor (HDACi) mitigates tumor growth via targeting HIF-1α, whereas underlying mechanism still requires investigation. In this research, we exposed ovarian cancer cell lines OV-90 and SKOV-3 to escalating concentrations of HDACi LBH589. As a result, cell viability was significantly suppressed and expression of HIF-1α was remarkably reduced along with decreased levels of signal molecules, including phosphoinositide 3-kinase (PI3K) and glycogen synthase kinase 3β (GSK3β) (P = 0.000). Interestingly, pVHL was expressed in a notably declining tendency (P = 0.000). Chaperone heat shock protein-70 (HSP70) was expressed in an ascending manner, whereas expression of chaperonin TCP-1α was reduced clearly (P = 0.000). Besides, co-inhibition of pVHL plus HDAC did not contribute to a remarkable difference in HIF-1α expression as compared with single HDAC inhibition. Furthermore, both cell lines were transfected with plasmids of VHL plus VHL binding protein-1 (VBP-1). Consequently, the expression of HIF-1α as well as lactate dehydrogenase-A (LDHA) was remarkably decreased (P = 0.000). These findings indicate HDACi may repress expression of HIF-1α via inhibiting PI3K and GSK3β and promote degradation of HIF-1α via HSP70, independent of pVHL. Additionally, a sophisticated network of HDAC and chaperones may involve in pVHL quality control.

Prefoldin subunits (PFDN1-6) serve as poor prognostic markers in gastric cancer

Prefoldin subunits (PFDN), primarily known for co-chaperone function associated with cytoskeletal rearrangement, have been found involved in epithelial–mesenchymal transition (EMT) and cancer progression. However, studies focusing on the roles of PFDN in gastric cancer (GC) remain limited. The present study aims to evaluate the prognostic values of PFDN in GC. Prognostic roles of PFDNs were analyzed via the Kaplan–Meier platform, followed by subset analysis within various clinical parameters. High mRNA expression of PFDN2, PFDN3 and PFDN4 displayed poor overall survival (OS) while PFDN5 displayed favorable OS. In HER2+ subset, PFDN2, PFDN3, PFDN4 and PFDN6 displayed poor OS. In human epidermal growth factor receptor 2 (HER2−) subset, PFDN2, PFDN3 and PFDN4 displayed poor OS. In intestinal type subset, PFDN1 and PFDN2 displayed poor OS. In diffuse-type subset, PFDN2 and PFDN6 displayed poor OS. In moderate differentiation type subset, PFDN1 displayed poor OS. In poor differentiation type subset, PFDN2 and PFDN6 displayed poor OS. In metastasis negative subset, PFDN1, PFDN2 and PFDN6 displayed poor OS. In lymph node (LN) positive subset, PFDN2 and PFDN5 displayed poor OS. The present study provided insightful clues into the poor prognostic values of PFDNs in GC patients.

The Role of Prefoldin and Its Subunits in Tumors and Their Application Prospects in Nanomedicine

Prefoldin (PFDN) is a hexameric chaperone complex that is widely found in eukaryotes and archaea and consists of six different subunits (PFDN1-6). Its main function is to transfer actin and tubulin monomers to the eukaryotic cell cytoplasmic chaperone protein (c-CPN) specific binding during the assembly of the cytoskeleton, to stabilize the newly synthesized peptides so that they can be folded correctly. The current study found that each subunit of PFDN has different functions, which are closely related to the occurrence, development and prognosis of tumors. However, the best characteristics of each subunit have not been fully affirmed. The connection between research and tumors can change the understanding of PFDN and further extend its potential prognostic role and structural function to cancer research and clinical practice. This article mainly reviews the role of canonical PFDN and its subunits in tumors and other diseases, and discusses the potential prospects of the unique structure and function of PFDN in nanomedicine.

Antibacterial and Anticancer Activities of Fenugreek Seed Extract

This work is about the utilization of fenugreek seed as an antibacterial and anticancer agents. The antibacterial activity of fenugreek seed extract on six pathological bacteria strains were specified through conventional biochemical tests using the Vitek2 automated system and diffusion agar method. The anticancer activities of fenugreek seed extract, on MCF-7 breast cancer cells, liver cancer HCAM cells and the non-cancerous Vero cell lines, were investigated using colorimetric MTT assay. Results showed that the highest activity of the extract of the seed was found on Staphylococcus aureus and Pseudomonas aeruginosa (22 mm and 17 mm diameter of inhibition zones respectively). The seed extract showed proliferative inhibition on MCF-7 cell line at a concentration of 400 µg/ml and 72 h of the incubation period. This was accompanied by insignificant apoptosis or necrosis. The seed extract showed no anticancer effect on liver and Vero cell lines. This work emphasizes that fenugreek seed extract is a potential source of antibacterial and anticancer agents.
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Differential HDAC1/2 network analysis reveals a role for prefoldin/CCT in HDAC1/2 complex assembly

HDAC1 and HDAC2 are components of several corepressor complexes (NuRD, Sin3, CoREST and MiDAC) that regulate transcription by deacetylating histones resulting in a more compact chromatin environment. This limits access of transcriptional machinery to genes and silences transcription. While using an AP-MS approach to map HDAC1/2 protein interaction networks, we noticed that N-terminally tagged versions of HDAC1 and HDAC2 did not assemble into HDAC corepressor complexes as expected, but instead appeared to be stalled with components of the prefoldin-CCT chaperonin pathway. These N-terminally tagged HDACs were also catalytically inactive. In contrast to the N-terminally tagged HDACs, C-terminally tagged HDAC1 and HDAC2 captured complete histone deacetylase complexes and the purified proteins had deacetylation activity that could be inhibited by SAHA (Vorinostat), a Class I/II HDAC inhibitor. This tag-mediated reprogramming of the HDAC1/2 protein interaction network suggests a mechanism whereby HDAC1 is first loaded into the CCT complex by prefoldin to complete folding, and then assembled into active, functional HDAC complexes. Imaging revealed that the prefoldin subunit VBP1 colocalises with nuclear HDAC1, suggesting that delivery of HDAC1 to the CCT complex happens in the nucleus.

Cytokeratin 18-associated Histone 3 Modulation in Hepatocellular Carcinoma: A Mini Review

Unstable cytokeratins are associated with tumor transformation in the development of human hepatocellular carcinoma. We previously demonstrated that the cytokeratin 18 was modulated and that a histone H3-specific modification occured, among members of the histone family, during the development of human hepatocellular carcinoma. Evidence suggested that the modification of histone H3 was highly correlated with the modulation of cytokeratin 18 and probably plays an important role in tumorigenesis of hepatocytes. Aberrant expression of histone deacetylase leading to imbalance between acetylation and deacetylation of histones may exhibit regulatory roles in tumor transformation. Recently we found that overexpression of histone deacetylase-1 and hypoacetylation of histone H3 were associated with hepatocellular carcinoma. The underlying roles of histone H3 modulation are discussed in this mini-review article.

Nano-Micelle of Moringa Oleifera Seed Oil Triggers Mitochondrial Cancer Cell Apoptosis

Cancer, a worldwide epidemic disease with diverse origins, involves abnormal cell growth with the potential to invade other parts of the body. Globally, it is the main cause of mortality and morbidity. To overcome the drawbacks of the commercially available chemotherapies, natural products-loaded nano-composites are recommended to improve cancer targetability and decrease the harmful impact on normal cells. This study aimed at exploring the anti-cancer impacts of Moringa oleifera seed oil in its free- (MO) and nano-formulations (MOn) through studying whether it mechanistically promotes mitochondrial apoptosis-mediating cell death. Mitochondrial-based cytotoxicity and flow cytometric-based apoptosis analyses were performed on cancer HepG2, MCF7, HCT 116, and Caco-2 cell lines against normal kidney BHK-21 cell line. The present study resulted that MOn triggered colorectal cancer Caco-2 and HCT 116 cytotoxicity via mitochondrial dysfunction more powerful than its free counterpart (MO). On the other side, MOn and MO remarkably induces HCT 116 mitochondrial apoptosis, while sparing normal BHK-21 cells with minimal cytotoxic effect. The present results concluded that nano-micelle of Moringa oleifera seed oil (MOn) can provide a novel therapeutic approach for colorectal and breast cancers via mitochondrial-mediated apoptosis, while sparing normal and even liver cancer cells a bit healthy or with minimal harmful effect. Intriguingly, MOn induced breast cancer not hepatocellular carcinoma cell death.

Prefoldin 1 promotes EMT and lung cancer progression by suppressing cyclin A expression

Prefoldin (PFDN) is a co-chaperone protein that is primarily known for its classic cytoplasmic functions in the folding of actin and tubulin monomers during cytoskeletal assembly. Here, we report a marked increase in prefoldin subunit 1 (PFDN1) levels during the transforming growth factor (TGF)-β1-mediated epithelial-mesenchymal transition (EMT) and in human lung tumor tissues. Interestingly, the nuclear localization of PFDN1 was also detected. These observations suggest that PFDN1 may be essential for important novel functions. Overexpression of PFDN1 induced EMT and cell invasion. In sharp contrast, knockdown of PFDN1 generated the opposite effects. Overexpression of PFDN1 was also found to induce lung tumor growth and metastasis. Further experiments showed that PFDN1 overexpression inhibits the expression of cyclin A. PFDN1 suppressed cyclin A expression by directly interacting with the cyclin A promoter at the transcriptional start site. Strikingly, cyclin A overexpression abolished the above PFDN1-mediated effects on the behavior of lung cancer cells, whereas cyclin A knockdown alone induced EMT and increased cell migration and invasion ability. This study reveals that the TGF-β1/PFDN1/cyclin A axis is essential for EMT induction and metastasis of lung cancer cells.

Silencing P2X7 receptor downregulates the expression of TCP-1 involved in lymphoma lymphatic metastasis

P2X₇R is an ATP-gated cation channel that participates in cell proliferation and apoptosis. TCP-1 assists with the protein folding. According to our previous research, the P2X₇R has a potential role in P388D1 lymphoid neoplasm cells dissemination to peripheral lymph nodes. In order to make a further exploration about the probable mechanism, the lymph nodes which metastasized by P2X₇R-silenced P388D1 cells or non-silenced cells were analyzed by 2DE and a MALDI-TOF-based proteomics approach. In the 64 proteins which were differentially expressed between two groups, TCP-1 was found to be significantly decreased in P2X₇R shRNA group compared to controls. This correlation was also found in subsequent experiments in vivo and in vitro. The positive correlation between P2X₇R and TCP-1 was also proved in both lymphoma and benign lymphadenopathy tissues from patients. It indicates that TCP-1 may be a crucial downstream molecular of P2X₇R and plays a novel role in lymphoid neoplasm metastasis.

Changes in the in vitro activity of platinum drugs when administered in two aliquots

BACKGROUND

The management of ovarian cancer remains a challenge. Because of the lack of early symptoms, it is often diagnosed at a late stage when it is likely to have metastasized beyond ovaries. Currently, platinum based chemotherapy is the primary treatment for the disease. However acquired drug resistance remains an on-going problem. As cisplatin brings about apoptosis by intrinsic and extrinsic pathways, this study aimed to determine changes in activity of platinum drugs when administered in two aliquots as against a bolus and sought to determine association with changes in GSH, speciation of platinum drugs and changes in protein expression.

METHODS

The efficacy of administering cisplatin, carboplatin and oxaliplatin in two aliquots with a time gap was investigated in ovarian A2780, A2780(cisR), A2780(ZD0473R) and SKOV-3 cell lines. The cellular accumulation of platinum, level of platinum - DNA binding and cellular glutathione level were determined, and proteomic studies were carried out to identify key proteins associated with platinum resistance in ovarian A2780(cisR) cancer cell line.

RESULTS

Much greater cell kill was observed with solutions left standing at room temperature than with freshly prepared solutions, indicating that the increase in activity on ageing was related to speciation of the drug in solution. Proteomic studies identified 72 proteins that were differentially expressed in A2780 and A2780(cisR) cell lines; 22 of them were restored back to normal levels as a result of synergistic treatments, indicating their relevance in enhanced drug action.

CONCLUSIONS

The proteins identified are relevant to several different cellular functions including invasion and metastasis, cell cycle regulation and proliferation, metabolic and biosynthesis processes, stress-related proteins and molecular chaperones, mRNA processing, cellular organization/cytoskeleton, cellular communication and signal transduction. This highlights the multifactorial nature of platinum resistance in which many different proteins with diverse functions play key roles. This means multiple strategies can be harnessed to overcome platinum resistance in ovarian cancer. The results of the studies can be significant both from fundamental and clinical view points.

Lentivirus-mediated Knockdown of HDAC1 Uncovers Its Role in Esophageal Cancer Metastasis and Chemosensitivity

Histone deacetylationase 1 (HDAC1) is ubiquitously expressed in various cell lines and tissues and play an important role of regulation gene expression. Overexpression of HDAC1 has been observed in various types of cancers, which indicated that it might be a target for cancer therapy. To test HDAC1 inhibition for cancer treatment, the gene expression of HDAC1 was knockdown mediated by a lentivirus system. Our data showed the gene expression of HDAC1 could be efficiently knockdown by RNAi mediated by lentivirus in esophageal carcinoma EC109 cells. Knockdown of HDAC1 led to significant decrease of cell growth and altered cell cycle distribution. The result of transwell assay showed that the numbers of cells travelled through the micropore membrane was significantly decreased as HDAC1 expression was knockdown. Moreover, HDAC1 knockdown inhibited the migration of EC109 cells as determining by scratch test. Additionally, enhancement of cisplatin-stimulated apoptosis was detected by HDAC1 knockdown. Our data suggested inhibition of HDAC1 expression by lentivirus mediated shRNA might be further applied for esophageal cancer chemotherapy.

Epigenetic targets in hepatocellular carcinoma cells: identification of chaperone protein complexes with histone deacetylases

AIMS

The study was designed to find out the protein complex(s) associated with HDAC3 in liver cancer using a modified form of affinity purification coupled with a mass spectrometry technique in HepG2 cells. The organ-specific requirement for HDAC1 and HDAC3 during liver formation in zebrafish and their altered expression in liver cancer tissues indicates they are indispensible for hepato-organogenesis and hepatocarcinogenesis. However, how they exert their function is unknown.

MATERIAL & METHODS

HepG2 cells were transfected with either mock or construct-containing HDAC3 using a C-terminal strepIII-HA tag as bait. The bait proteins were purified by double affinity columns and were analyzed on a Thermo LTQ Orbitrap™ (Thermo Scientific, MA, USA) chromatography system.

RESULTS

Affinity purification coupled with mass spectrometry resulted in the identification of 24 putative binders of HDAC3 in HepG2 cells. The majority (83%) of these are novel interactions are reported for the first time in this study.

CONCLUSION

This is the first study reporting the affinity purification and identification of protein complexes with two closely related proteins in one cell line. The novel HDAC1 and HDAC3 complexes identified in HepG2 cells could serve as a platform for the design of future therapeutic medicine for the treatment of liver cancer.

In vitro Evaluation of Cytotoxic Activities of Essential Oil from Moringa oleifera Seeds on HeLa, HepG2, MCF-7, CACO-2 and L929 Cell Lines

Moringa oleifera Lam. (Moringaceae) is widely consumed in tropical and subtropical regions for their valuable nutritional and medicinal characteristics. Recently, extensive research has been conducted on leaf extracts of M. oleifera to evaluate their potential cytotoxic effects. However, with the exception of antimicrobial and antioxidant activities, little information is present on the cytotoxic activity of the essential oil obtained from M. oleifera seeds. Therefore, the present investigation was designed to investigate the potential cytotoxic activity of seed essential oil obtained from M. oleifera on HeLa, HepG2, MCF-7, CACO-2 and L929 cell lines. The different cell lines were subjected to increasing oil concentrations ranging from 0.15 to 1 mg/mL for 24h, and the cytotoxicity was assessed using MTT assay. All treated cell lines showed a significant reduction in cell viability in response to the increasing oil concentration. Moreover, the reduction depended on the cell line as well as the oil concentration applied. Additionally, HeLa cells were the most affected cells followed by HepG2, MCF-7, L929 and CACO-2, where the percentages of cell toxicity recorded were 76.1, 65.1, 59.5, 57.0 and 49.7%, respectively. Furthermore, the IC50 values obtained for MCF-7, HeLa and HepG2 cells were 226.1, 422.8 and 751.9 μg/mL, respectively. Conclusively, the present investigation provides preliminary results which suggest that seed essential oil from M. oleifera has potent cytotoxic activities against cancer cell lines.

Targeting Histone Deacetylases in Diseases: Where Are We?

SIGNIFICANCE

Epigenetic inactivation of pivotal genes involved in cell growth is a hallmark of human pathologies, in particular cancer. Histone acetylation balance obtained through opposing actions of histone deacetylases (HDACs) and histone acetyltransferases is one epigenetic mechanism controlling gene expression and is, thus, associated with disease etiology and progression. Interfering pharmacologically with HDAC activity can correct abnormalities in cell proliferation, migration, vascularization, and death.

RECENT ADVANCES

Histone deacetylase inhibitors (HDACi) represent a new class of cytostatic agents that interfere with the function of HDACs and are able to increase gene expression by indirectly inducing histone acetylation. Several HDACi, alone or in combination with DNA-demethylating agents, chemopreventive, or classical chemotherapeutic drugs, are currently being used in clinical trials for solid and hematological malignancies, and are, thus, promising candidates for cancer therapy.

CRITICAL ISSUES

(i) Non-specific (off-target) HDACi effects due to activities unassociated with HDAC inhibition. (ii) Advantages/disadvantages of non-selective or isoform-directed HDACi. (iii) Limited number of response-predictive biomarkers. (iv) Toxicity leading to dysfunction of critical biological processes.

FUTURE DIRECTIONS

Selective HDACi could achieve enhanced clinical utility by reducing or eliminating the serious side effects associated with current first-generation non-selective HDACi. Isoform-selective and pan-HDACi candidates might benefit from the identification of biomarkers, enabling better patient stratification and prediction of response to treatment.