Sensitization of hepatocellular carcinoma cells to HDACi is regulated through hsa-miR-342-5p/CFL1.

BACKGROUND: Increased prevalence of hepatocellular carcinoma (HCC) remains a global health challenge. HCC chemoresistance is a clinical obstacle for its management. Aberrant miRNA expression is a hallmark for both cancer progression and drug resistance. However, it is unclear which miRNAs are involved in HCC chemoresistance. METHODS: MicroRNA microarray analysis revealed a differential expression profile of microRNAs between the hepatocellular carcinoma HA22T cell line and the HDACi-R cell line, which was validated by quantitative real-time PCR (qRT-PCR). To determine the biological function of miR-342-5p and the mechanism of the microRNA-342-5p/CFL1 axis in hepatocellular carcinoma HDACi resistance, loss- and gain-of-function studies were conducted in vitro. RESULTS: Here we demonstrated the molecular mechanism of histone deacetylase inhibitor (HDACi) resistance in HCC. Differential miRNA expression analysis showed significant down regulation of miR-342-5p in HDACi-R cells than in parental HA22T cells. Mimics of miR-342-5p enhanced apoptosis through upregulation of Bax, cyto-C, cleaved-caspase-3 expressions with concomitant decline in anti-apoptotic protein (Bcl-2) in HDACi-R cells. Although HDACi did not increase cell viability of HDACi-R, overexpression of miR-342-5p decreased cofilin-1 expression, upregulated reactive oxygen species (ROS) mediated apoptosis, and sensitized HDACi-R to HDACi in a dose-dependent manner. CONCLUSION: Our findings demonstrated the critical role of miR-342-5p in HDACi resistance of HCC and that this mechanism might be attributed to miR-342-5p/cofilin-1 regulation.

Structure-Based Identification of Novel Histone Deacetylase 4 (HDAC4) Inhibitors.

Histone deacetylases (HDACs) are important cancer drug targets. Existing FDA-approved drugs target the catalytic pocket of HDACs, which is conserved across subfamilies (classes) of HDAC. However, engineering specificity is an important goal. Herein, we use molecular modeling approaches to identify and target potential novel pockets specific to Class IIA HDAC-HDAC4 at the interface between HDAC4 and the transcriptional corepressor component protein NCoR. These pockets were screened using an ensemble docking approach combined with consensus scoring to identify compounds with a different binding mechanism than the currently known HDAC modulators. Binding was compared in experimental assays between HDAC4 and HDAC3, which belong to a different family of HDACs. HDAC4 was significantly inhibited by compound 88402 but not HDAC3. Two other compounds (67436 and 134199) had IC50 values in the low micromolar range for both HDACs, which is comparable to the known inhibitor of HDAC4, SAHA (Vorinostat). However, both of these compounds were significantly weaker inhibitors of HDAC3 than SAHA and thus more selective, albeit to a limited extent. Five compounds exhibited activity on human breast carcinoma and/or urothelial carcinoma cell lines. The present result suggests potential mechanistic and chemical approaches for developing selective HDAC4 modulators.

Combination of HDAC and FYN inhibitors in synovial sarcoma treatment.

The SS18-SSX fusion protein is an oncogenic driver in synovial sarcoma. At the molecular level, SS18-SSX functions as both an activator and a repressor to coordinate transcription of different genes responsible for tumorigenesis. Here, we identify the proto-oncogene FYN as a new SS18-SSX target gene and examine its relation to synovial sarcoma therapy. FYN is a tyrosine kinase that promotes cancer growth, metastasis and therapeutic resistance, but SS18-SSX appears to negatively regulate FYN expression in synovial sarcoma cells. Using both genetic and histone deacetylase inhibitor (HDACi)-based pharmacologic approaches, we show that suppression of SS18-SSX leads to FYN reactivation. In support of this notion, we find that blockade of FYN activity synergistically enhances HDACi action to reduce synovial sarcoma cell proliferation and migration. Our results support a role for FYN in attenuation of anti-cancer activity upon inhibition of SS18-SSX function and demonstrate the feasibility of targeting FYN to improve the effectiveness of HDACi treatment against synovial sarcoma.

A Novel Class I HDAC Inhibitor, AW01178, Inhibits Epithelial-Mesenchymal Transition and Metastasis of Breast Cancer.

Epithelial-mesenchymal transition (EMT) refers to the transformation of polar epithelial cells into motile mesenchymal cells under specific physiological or pathological conditions, thus promoting the metastasis of cancer cells. Epithelial cadherin (E-cadherin) is a protein that plays an important role in the acquisition of tumor cell motility and serves as a key EMT epithelial marker. In the present study, AW01178, a small-molecule compound with potential therapeutic efficacy, was identified via in-cell Western high-throughput screening technology using E-cadherin as the target. The compound induced the upregulation of E-cadherin at both mRNA and protein levels and inhibited the EMT of breast cancer cells in vitro as well as metastasis in vivo. Mechanistically, AW01178 is a novel benzacetamide histone deacetylase inhibitor (HDACi) mainly targeting class I histone deacetylases. AW01178 promoted the transcription and expression of E-cadherin through enhancing the acetylation level of histone H3 in the E-cadherin promoter region, thereby inhibiting the metastasis of breast cancer cells. The collective findings support the potential utility of the novel HDACi compound identified in this study, AW01178, as a therapeutic drug for breast cancer and highlight its value for the future development of HDACi structures as anticancer drugs.

Combination of dual JAK/HDAC inhibitor with regorafenib synergistically reduces tumor growth, metastasis, and regorafenib-induced toxicity in colorectal cancer.

BACKGROUND: Treatment with regorafenib, a multiple-kinase inhibitor, to manage metastatic colorectal cancers (mCRCs) shows a modest improvement in overall survival but is associated with severe toxicities. Thus, to reduce regorafenib-induced toxicity, we used regorafenib at low concentration along with a dual JAK/HDAC small-molecule inhibitor (JAK/HDACi) to leverage the advantages of both JAK and HDAC inhibition to enhance antitumor activity. The therapeutic efficacy and safety of the combination treatment was evaluated with CRC models. METHODS: The cytotoxicity of JAK/HDACi, regorafenib, and their combination were tested with normal colonic and CRC cells exhibiting various genetic backgrounds. Kinomic, ATAC-seq, RNA-seq, cell cycle, and apoptosis analyses were performed to evaluate the cellular functions/molecular alterations affected by the combination. Efficacy of the combination was assessed using patient-derived xenograft (PDX) and experimental metastasis models of CRC. To evaluate the interplay between tumor, its microenvironment, and modulation of immune response, MC38 syngeneic mice were utilized. RESULTS: The combination therapy decreased cell viability; phosphorylation of JAKs, STAT3, EGFR, and other key kinases; and inhibited deacetylation of histone H3K9, H4K8, and alpha tubulin proteins. It induced cell cycle arrest at G0-G1 phase and apoptosis of CRC cells. Whole transcriptomic analysis showed that combination treatment modulated molecules involved in apoptosis, extracellular matrix-receptor interaction, and focal adhesion pathways. It synergistically reduces PDX tumor growth and experimental metastasis, and, in a syngeneic mouse model, the treatment enhances the antitumor immune response as evidenced by higher infiltration of CD45 and cytotoxic cells. Pharmacokinetic studies showed that combination increased the bioavailability of regorafenib. CONCLUSIONS: The combination treatment was more effective than with regorafenib or JAK/HDACi alone, and had minimal toxicity. A clinical trial to evaluate this combination for treatment of mCRCs is warranted.

The Bioequivalence of Abexinostat (CRA-024781) Tosylate Tablets (20 mg) in Chinese Healthy Subjects Under Fasting Conditions.

This study aimed to investigate the pharmacokinetic parameters of single oral administration of postchange and prechange abexinostat (CRA-024781) tosylate tablets in Chinese healthy subjects under fasting conditions, and assess the bioequivalence (BE) of the 2 formulations (Test [T1] and Reference [T2]). This study was a randomized, open-label, 2-formulation, fasting administration, single-dose, 2-sequence, 2-cycle, crossover BE study. Thirty-six subjects were enrolled in the study and 33 subjects completed 2 cycles. The plasma concentrations were determined by liquid chromatography-tandem mass spectrometry. The 90% confidence intervals (CIs) for the Cmax, AUC0-t, and AUC0-∞ of CRA-024781 and its 2 major metabolites (PCI-27789 and PCI-27887, both metabolites are pharmacologically inactive on HDAC1) fell within the acceptable range of 80%-125%. The results suggest that the CRA-024781 test preparation (Test [T1]) is bioequivalent to the reference preparation (Reference [T2]) in healthy Chinese subjects under fasting conditions.

HDAC inhibitor regulates the tumor immune microenvironment via pyroptosis in triple negative breast cancer.

Pyroptosis, an inflammatory form of cell death, promotes the release of immunogenic substances and stimulates immune cell recruitment, a process, which could turn cold tumors into hot ones. Thus, instigating pyroptosis in triple-negative breast cancer (TNBC) serves as a viable method for restoring antitumor immunity. We analyzed the effects of Histone Deacetylase Inhibitors (HDACi) on TNBC cells using the Cell Counting Kit-8 and colony formation assay. Apoptosis and lactate dehydrogenase (LDH) release assays were utilized to determine the form of cell death. The pyroptotic executor was validated by quantitative real-time polymerase chain reaction and western blot. Transcriptome was analyzed to investigate pyroptosis-inducing mechanisms. A subcutaneously transplanted tumor model was generated in BALB/c mice to evaluate infiltration of immune cells. HDACi significantly diminished cell proliferation, and pyroptotic "balloon"-like cells became apparent. HDACi led to an intra and extracellular material exchange, signified by the release of LDH and the uptake of propidium iodide. Among the gasdermin family, TNBC cells expressed maximum quantities of GSDME, and expression of GSDMA, GSDMB, and GSDME were augmented post HDACi treatment. Pyroptosis was instigated via the activation of the caspase 3-GSDME pathway with the potential mechanisms being cell cycle arrest and altered intracellular REDOX balance due to aberrant glutathione metabolism. In vivo experiments demonstrated that HDACi can activate pyroptosis, limit tumor growth, and escalate CD8+ lymphocyte and CD11b+ cell infiltration along with an increased presence of granzyme B in tumors. HDACi can instigate pyroptosis in TNBC, promoting infiltration of immune cells and consequently intensifying the efficacy of anticancer immunity.

Inhibition of HDAC activity directly reprograms murine embryonic stem cells to trophoblast stem cells.

Embryonic stem cells (ESCs) can differentiate into all cell types of the embryonic germ layers. ESCs can also generate totipotent 2C-like cells and trophectodermal cells. However, these latter transitions occur at low frequency due to epigenetic barriers, the nature of which is not fully understood. Here, we show that treating mouse ESCs with sodium butyrate (NaB) increases the population of 2C-like cells and enables direct reprogramming of ESCs into trophoblast stem cells (TSCs) without a transition through a 2C-like state. Mechanistically, NaB inhibits histone deacetylase activities in the LSD1-HDAC1/2 corepressor complex. This increases acetylation levels in the regulatory regions of both 2C- and TSC-specific genes, promoting their expression. In addition, NaB-treated cells acquire the capacity to generate blastocyst-like structures that can develop beyond the implantation stage in vitro and form deciduae in vivo. These results identify how epigenetics restrict the totipotent and trophectoderm fate in mouse ESCs.

Synergistic activities of Panobinostat and doxorubicin in soft tissue sarcomas.

BACKGROUND: Soft tissue sarcomas (STS) are rare diseases typically arising from connective tissues in children and adults. However, chemotherapies involved in the treatment of STS may cause toxic side effects and multi-drug chemoresistance, making the treatment even more challenging. Histone deacetylase inhibitors (HDACi) are epigenetic agents which have shown anti-tumor effects as single agent as well as combination use with other drugs. Our project intends to prove the same effects in STS. METHODS: Panobinostat (LBH589) plus doxorubicin was selected for investigations based on our previous research. Tumor xenografts were tried in an epithelioid sarcoma model to validate good synergy effects in vivo and a leiomyosarcoma model was used as a negative comparison group. Gene profile changes were studied afterwards. The possible pathway changes caused by HDACi were explored and validated by several assays. RESULTS: Synergy effect of LBH589 plus doxorubicin was successfully validated in STS cell lines and an epithelioid sarcoma mice model. We tried to reduce the dose of doxorubicin to a lower level and found the drug combination can still inhibit tumor size in mice. Furthermore, gene profile changes caused by LBH589 was studied by RNA-Sequencing analysis. Results showed LBH589 can exert effects on a group of target genes which can regulate potential biological functions especially in the cell cycle pathway.

Molecular docking of curcumin and curcuminoids as human Zn+ dependent histone deacetylase (HDAC) enzyme inhibitors.

Chemotherapy is one of the most well-established and effective cancer treatments available. However, non-tumor-associated damage restrict the treatment's effectiveness and safety. Our growing understanding of cancer epigenetics has resulted in new therapeutic options and the potential of better patient outcomes in recent decades. In cancer, epigenetic changes are widespread, particularly increased expression and activity of histone deacetylases (HDACs). Epi-drugs are chemical agents that modify the structure of DNA and chromatin facilitating disruption of transcriptional and post-transcriptional changes. First generation epi-drugs include HDAC inhibitors (HDACi) (approved to treat hematological malignancies) harbor various adverse effects demanding the discovery and development of potential natural HDACi that might benefit cancer treatment especially in hematological malignancies. Curcumin (diferuloylmethane), a polyphenolic, component of Curcuma longa, is a well-known anti-inflammatory, anti-oxidative, and anti-lipidemic agent and has recently been shown to be a pan HDACi. Yet the potential of other curcuminoids in Curcuma longa as pan HDACi remains unexplored. (i) To virtually screen curcumin and curcuminoids (Desmethoxycurcumin [DMC] & Bisdemethoxycurcumin [BDMC]) against human Histone deacetylase (HDAC) class I, II and IV enzymes in comparison to their pan HDAC inhibition activity with FDA approved human HDACis available in market and also (ii) to predict the drug likeness property and ADME/ toxicity of curcumin, curcuminoids and approved HDACis via computational approach. Homology modelling followed by docking was performed for human HDAC class I, II and IV enzymes with curcumin, Desmethoxycurcumin, Bisdemethoxycurcumin and with 5 reference HDACi compounds Vorinostat (SAHA), Trichostatin A (TSA), Chidamide, Romidepsin, and Panobinostat to understand the protein -ligand interactions and binding efficiencies. Further, the study ligands with low binding energy were predicted for pharmacokinetic properties and Lipinski's rule of 5. Our study revealed that BDMC followed by DMC and curcumin had high inhibitory effect by interacting at the active site of Zn+ HDACs similar to that of the standard HDACi (curcumin, DMC, BDMC, Belinostat, Chidamide, Romidepsin, Panobinostat, Trichostatin A and Vorinostat). Likewise, all of the chosen ligand molecules, with the exception of Romidepsin (refractive index > 130 m3mol-1), adhered to Lipinski's rule of five and none of the natural compounds (curcumin, DMC, BDMC) did report any toxicity and mutagenic property also, the lethal doses (LD50) of all the natural compounds were higher when compared to chemical drugs. BDMC could be a potential pan HDACi than curcumin and DMC owing to high binding affinity among human Zn+ HDACs. The results of our present study can be useful for the design and development of novel compounds having better HDAC inhibitory activity against several types of cancers. Moreover, these findings could be validated with invitro investigations and by clinical trials to evaluate the survival outcomes in cancer patients when treated with the natural HDACi along with standard chemo regimen. Supplementary Information: The online version contains supplementary material available at 10.1007/s40203-024-00221-4.

New synergistic combination therapy approaches with HDAC inhibitor quisinostat, cisplatin or PARP inhibitor talazoparib for urothelial carcinoma.

Urothelial carcinoma (UC) urgently requires new therapeutic options. Histone deacetylases (HDAC) are frequently dysregulated in UC and constitute interesting targets for the development of alternative therapy options. Thus, we investigated the effect of the second generation HDAC inhibitor (HDACi) quisinostat in five UC cell lines (UCC) and two normal control cell lines in comparison to romidepsin, a well characterized HDACi which was previously shown to induce cell death and cell cycle arrest. In UCC, quisinostat led to cell cycle alterations, cell death induction and DNA damage, but was well tolerated by normal cells. Combinations of quisinostat with cisplatin or the PARP inhibitor talazoparib led to decrease in cell viability and significant synergistic effect in five UCCs and platinum-resistant sublines allowing dose reduction. Further analyses in UM-UC-3 and J82 at low dose ratio revealed that the mechanisms included cell cycle disturbance, apoptosis induction and DNA damage. These combinations appeared to be well tolerated in normal cells. In conclusion, our results suggest new promising combination regimes for treatment of UC, also in the cisplatin-resistant setting.

Unveiling the role of HP1α-HDAC1-STAT1 axis as a therapeutic target for HP1α-positive intrahepatic cholangiocarcinoma.

BACKGROUND: Intrahepatic cholangiocarcinoma (ICCA) is a heterogeneous group of malignant tumors characterized by high recurrence rate and poor prognosis. Heterochromatin Protein 1α (HP1α) is one of the most important nonhistone chromosomal proteins involved in transcriptional silencing via heterochromatin formation and structural maintenance. The effect of HP1α on the progression of ICCA remained unclear. METHODS: The effect on the proliferation of ICCA was detected by experiments in two cell lines and two ICCA mouse models. The interaction between HP1α and Histone Deacetylase 1 (HDAC1) was determined using Electrospray Ionization Mass Spectrometry (ESI-MS) and the binding mechanism was studied using immunoprecipitation assays (co-IP). The target gene was screened out by RNA sequencing (RNA-seq). The occupation of DNA binding proteins and histone modifications were predicted by bioinformatic methods and evaluated by Cleavage Under Targets and Tagmentation (CUT & Tag) and Chromatin immunoprecipitation (ChIP). RESULTS: HP1α was upregulated in intrahepatic cholangiocarcinoma (ICCA) tissues and regulated the proliferation of ICCA cells by inhibiting the interferon pathway in a Signal Transducer and Activator of Transcription 1 (STAT1)-dependent manner. Mechanistically, STAT1 is transcriptionally regulated by the HP1α-HDAC1 complex directly and epigenetically via promoter binding and changes in different histone modifications, as validated by high-throughput sequencing. Broad-spectrum HDAC inhibitor (HDACi) activates the interferon pathway and inhibits the proliferation of ICCA cells by downregulating HP1α and targeting the heterodimer. Broad-spectrum HDACi plus interferon preparation regimen was found to improve the antiproliferative effects and delay ICCA development in vivo and in vitro, which took advantage of basal activation as well as direct activation of the interferon pathway. HP1α participates in mediating the cellular resistance to both agents. CONCLUSIONS: HP1α-HDAC1 complex influences interferon pathway activation by directly and epigenetically regulating STAT1 in transcriptional level. The broad-spectrum HDACi plus interferon preparation regimen inhibits ICCA development, providing feasible strategies for ICCA treatment. Targeting the HP1α-HDAC1-STAT1 axis is a possible strategy for treating ICCA, especially HP1α-positive cases.

Current treatment strategies targeting histone deacetylase inhibitors in acute lymphocytic leukemia: a systematic review.

Acute lymphocytic leukemia is a hematological malignancy that primarily affects children. Long-term chemotherapy is effective, but always causes different toxic side effects. With the application of a chemotherapy-free treatment strategy, we intend to demonstrate the most recent results of using one type of epigenetic drug, histone deacetylase inhibitors, in ALL and to provide preclinical evidence for further clinical trials. In this review, we found that panobinostat (LBH589) showed positive outcomes as a monotherapy, whereas vorinostat (SAHA) was a better choice for combinatorial use. Preclinical research has identified chidamide as a potential agent for investigation in more clinical trials in the future. In conclusion, histone deacetylase inhibitors play a significant role in the chemotherapy-free landscape in cancer treatment, particularly in acute lymphocytic leukemia.

Butyrate as a promising therapeutic target in cancer: From pathogenesis to clinic (Review).

Cancer is one of the leading causes of mortality worldwide. The etiology of cancer has not been fully elucidated yet, and further enhancements are necessary to optimize therapeutic efficacy. Butyrate, a short­chain fatty acid, is generated through gut microbial fermentation of dietary fiber. Studies have unveiled the relevance of butyrate in malignant neoplasms, and a comprehensive understanding of its role in cancer is imperative for realizing its full potential in oncological treatment. Its full antineoplastic effects via the activation of G protein­coupled receptors and the inhibition of histone deacetylases have been also confirmed. However, the underlying mechanistic details remain unclear. The present study aimed to review the involvement of butyrate in carcinogenesis and its molecular mechanisms, with a particular emphasis on its association with the efficacy of tumor immunotherapy, as well as discussing relevant clinical studies on butyrate as a therapeutic target for neoplastic diseases to provide new insights into cancer treatment.

Butyrate's (a short-chain fatty acid) microbial synthesis, absorption, and preventive roles against colorectal and lung cancer.

Butyrate, a short-chain fatty acid (SCFA) produced by bacterial fermentation of fiber in the colon, is a source of energy for colonocytes. Butyrate is essential for improving gastrointestinal (GI) health since it helps colonocyte function, reduces inflammation, preserves the gut barrier, and fosters a balanced microbiome. Human colonic butyrate producers are Gram-positive firmicutes, which are phylogenetically varied. The two most prevalent subgroups are associated with Eubacterium rectale/Roseburia spp. and Faecalibacterium prausnitzii. Now, the mechanism for the production of butyrate from microbes is a very vital topic to know. In the present study, we discuss the genes encoding the core of the butyrate synthesis pathway and also discuss the butyryl-CoA:acetate CoA-transferase, instead of butyrate kinase, which usually appears to be the enzyme that completes the process. Recently, butyrate-producing microbes have been genetically modified by researchers to increase butyrate synthesis from microbes. The activity of butyrate as a histone deacetylase inhibitor (HDACi) has led to several clinical trials to assess its effectiveness as a potential cancer treatment. Among various significant roles, butyrate is the main energy source for intestinal epithelial cells, which helps maintain colonic homeostasis. Moreover, people with non-small-cell lung cancer (NSCLC) have distinct gut microbiota from healthy adults and frequently have dysbiosis of the butyrate-producing bacteria in their guts. So, with an emphasis on colon and lung cancer, this review also discusses how the microbiome is crucial in preventing the progression of certain cancers through butyrate production. Further studies should be performed to investigate the underlying mechanisms of how these specific butyrate-producing bacteria can control both colon and lung cancer progression and prognosis.

Gαi2 Protein Inhibition Blocks Chemotherapy- and Anti-Androgen-Induced Prostate Cancer Cell Migration.

We have previously shown that heterotrimeric G-protein subunit alphai2 (Gαi2) is essential for cell migration and invasion in prostate, ovarian and breast cancer cells, and novel small molecule inhibitors targeting Gαi2 block its effects on migratory and invasive behavior. In this study, we have identified potent, metabolically stable, second generation Gαi2 inhibitors which inhibit cell migration in prostate cancer cells. Recent studies have shown that chemotherapy can induce the cancer cells to migrate to distant sites to form metastases. In the present study, we determined the effects of taxanes (docetaxel), anti-androgens (enzalutamide and bicalutamide) and histone deacetylase (HDAC) inhibitors (SAHA and SBI-I-19) on cell migration in prostate cancer cells. All treatments induced cell migration, and simultaneous treatments with new Gαi2 inhibitors blocked their effects on cell migration. We concluded that a combination treatment of Gαi2 inhibitors and chemotherapy could blunt the capability of cancer cells to migrate and form metastases.

HDAC inhibitors target IRS4 to enhance anti­AR therapy in AR­positive triple­negative breast cancer.

Triple­negative breast cancer (TNBC) is the most malignant subtype of breast cancer. Androgen receptor (AR) has been identified as a potential therapeutic target for AR­positive TNBC; however, clinical trials have not yet produced an effective treatment. The present study aimed to identify a novel treatment regimen to improve the prognosis of AR­positive TNBC. First, a combination of an AR inhibitor (enzalutamide, Enz) and a selective histone deacetylase inhibitor (chidamide, Chid) was used to treat AR­positive TNBC cell lines, and a synergistic effect of these drugs was observed. The combination treatment inhibited cell proliferation and migration by arresting the cell cycle at the G2/M phase. Subsequently, next­generation sequencing was performed to detect changes in gene regulation. The results showed that the PI3K/Akt signalling pathway was significantly inhibited by the combination treatment of Enz and Chid. Gene Set Enrichment Analysis revealed that the combination group was significantly enriched in KRAS signalling. Analysis of the associated genes revealed that insulin receptor substrate 4 (IRS4) may have a critical role in blocking the activation of KRAS signalling. In a mouse xenograft model, combination treatment also inhibited the PI3K/Akt signalling pathway by upregulating the expression of IRS4 and thereby suppressing tumour growth. In conclusion, the results of the present study revealed that combination treatment with Enz and Chid can upregulate IRS4, which results in the blocking of KRAS signalling and suppression of tumour growth. It may be hypothesised that the expression levels of IRS4 could be used as a biomarker for screening patients with AR­positive TNBC using Enz and Chid combination therapy.

Antitumor efficacy of a sequence-specific DNA-targeted γPNA-based c-Myc inhibitor.

Targeting oncogenes at the genomic DNA level can open new avenues for precision medicine. Significant efforts are ongoing to target oncogenes using RNA-targeted and protein-targeted platforms, but no progress has been made to target genomic DNA for cancer therapy. Here, we introduce a gamma peptide nucleic acid (γPNA)-based genomic DNA-targeted platform to silence oncogenes in vivo. γPNAs efficiently invade the mixed sequences of genomic DNA with high affinity and specificity. As a proof of concept, we establish that γPNA can inhibit c-Myc transcription in multiple cell lines. We evaluate the in vivo efficacy and safety of genomic DNA targeting in three pre-clinical models. We also establish that anti-transcription γPNA in combination with histone deacetylase inhibitors and chemotherapeutic drugs results in robust antitumor activity in cell-line- and patient-derived xenografts. Overall, this strategy offers a unique therapeutic platform to target genomic DNA to inhibit oncogenes for cancer therapy.

Discussion on structure classification and regulation function of histone deacetylase and their inhibitor.

Epigenetic regulation of genes through posttranslational regulation of proteins is a well-explored approach for disease treatment, particularly in cancer chemotherapy. Histone deacetylases have shown significant potential as effective drug targets in therapeutic studies aiming to restore epigenetic normality in oncology. Besides their role in modifying histones, histone deacetylases can also catalyze the deacetylation of various nonhistone proteins and participate in the regulation of multiple biological processes. This paper provides a review of the classification, structure, and functional characteristics of the four classes of human histone deacetylases. The increasing abundance of structural information on HDACs has led to the gradual elucidation of structural differences among subgroups and subtypes. This has provided a reasonable explanation for the selectivity of certain HDAC inhibitors. Currently, the US FDA has approved a total of six HDAC inhibitors for marketing, primarily for the treatment of various hematological tumors and a few solid tumors. These inhibitors all have a common pharmacodynamic moiety consisting of three parts: CAP, ZBG, and Linker. In this paper, the structure-effect relationship of HDAC inhibitors is explored by classifying the six HDAC inhibitors into three main groups: isohydroxamic acids, benzamides, and cyclic peptides, based on the type of inhibitor ZBG. However, there are still many questions that need to be answered in this field. In this paper, the structure-functional characteristics of HDACs and the structural information of the pharmacophore model and enzyme active region of HDAC is are considered, which can help to understand the inhibition mechanism of the compounds as well as the rational design of HDACs. This paper integrates the structural-functional characteristics of HDACs as well as the pharmacophore model of HDAC is and the structural information of the enzymatic active region, which not only contributes to the understanding of the inhibition mechanism of the compounds, but also provides a basis for the rational design of HDAC inhibitors.

CUDC-907, a dual PI3K/histone deacetylase inhibitor, increases meta-iodobenzylguanidine uptake (123/131I-mIBG) in vitro and in vivo: a promising candidate for advancing theranostics in neuroendocrine tumors.

BACKGROUND: Neuroblastoma (NB) and pheochromocytoma/paraganglioma (PHEO/PGL) are neuroendocrine tumors. Imaging of these neoplasms is performed by scintigraphy after injection of radiolabeled meta-iodobenzylguanidine (mIBG), a norepinephrine analog taken up by tumoral cells through monoamine transporters. The pharmacological induction of these transporters is a promising approach to improve the imaging and therapy (theranostics) of these tumors. METHODS: Transporters involved in mIBG internalization were identified by using transfected Human Embryonic Kidney (HEK) cells. Histone deacetylase inhibitors (HDACi) and inhibitors of the PI3K/AKT/mTOR pathway were tested in cell lines to study their effect on mIBG internalization. Studies in xenografted mice were performed to assess the effect of the most promising HDACi on 123I-mIBG uptake. RESULTS: Transfected HEK cells demonstrated that the norepinephrine and dopamine transporter (NET and DAT) avidly internalizes mIBG. Sodium-4-phenylbutyrate (an HDACi), CUDC-907 (a dual HDACi and PI3K inhibitor), BGT226 (a PI3K inhibitor) and VS-5584 and rapamycin (two inhibitors of mTOR) increased mIBG internalization in a neuroblastoma cell line (IGR-NB8) by 2.9-, 2.1-, 2.5-, 1.5- and 1.3-fold, respectively, compared with untreated cells. CUDC-907 also increased mIBG internalization in two other NB cell lines and in one PHEO cell line. We demonstrated that mIBG internalization occurs primarily through the NET. In xenografted mice with IGR-NB8 cells, oral treatment with 5 mg/kg of CUDC-907 increased the tumor uptake of 123I-mIBG by 2.3- and 1.9-fold at 4 and 24 h post-injection, respectively, compared to the untreated group. CONCLUSIONS: Upregulation of the NET by CUDC-907 lead to a better internalization of mIBG in vitro and in vivo.