Histone Acetylation Research Articles

Network medicine informed multiomics integration identifies drug targets and repurposable medicines for Amyotrophic Lateral Sclerosis

Amyotrophic Lateral Sclerosis (ALS) is a devastating, immensely complex neurodegenerative disease by lack of effective treatments. We developed a network medicine methodology via integrating human brain multi-omics data to prioritize drug targets and repurposable treatments for ALS. We leveraged non-coding ALS loci effects from genome-wide associated studies (GWAS) on human brain expression quantitative trait loci (QTL) (eQTL), protein QTL (pQTL), splicing QTL (sQTL), methylation QTL (meQTL), and histone acetylation QTL (haQTL). Using a network-based deep learning framework, we identified 105 putative ALS-associated genes enriched in known ALS pathobiological pathways. Applying network proximity analysis of predicted ALS-associated genes and drug-target networks under the human protein-protein interactome (PPI) model, we identified potential repurposable drugs (i.e., Diazoxide and Gefitinib) for ALS. Subsequent validation established preclinical evidence for top-prioritized drugs. In summary, we presented a network-based multi-omics framework to identify drug targets and repurposable treatments for ALS and other neurodegenerative disease if broadly applied.

Unlocking the Epigenetic Symphony: Histone Acetylation Orchestration in Bone Remodeling and Diseases.

Histone acetylation orchestrates a complex symphony of gene expression that controls cellular fate and activities, including the intricate processes of bone remodeling. Despite its proven significance, a systematic illustration of this process has been lacking due to its complexity, impeding clinical application. In this review, we delve into the central regulators of histone acetylation, unveiling their multifaceted roles in modulating bone physiology. We explore both contradictory and overlapping roles among these regulators and assess their potential as therapeutic targets for various bone disorders. Furthermore, we highlight current applications and discuss looming questions for a more effective use of epigenetic therapy in bone diseases, aiming to address gaps in knowledge and clinical practice. By providing a panoramic view of histone acetylation's impact on bone health and disease, this review unveils promising avenues for therapeutic intervention and enhances our understanding of skeletal physiology, crucial for improving therapeutical outcomes and quality of patients' life.

SIRT2 deacetylates and decreases the expression of FOXM1 in colon cancer.

New FOXM1-specific inhibitors with the potential to be used for therapeutic purposes are under extensive research. We hypothesized that deacetylation of FOXM1 would decrease protein expression, thus providing novel therapeutic management of colon cancers. Immunostaining was used to determine FOXM1 and SIRT2 expressions in human colon cancer tissue microarrays (n = 90) from Stage I to Stage IV. SIRT2-FOXM1 interaction was evaluated in colon cancer cells using immunoprecipitation. Deacetylation of FOXM1 via SIRT2 was determined using in vitro deacetylation assays. FOXM1 could be hyper-acetylated when p300 and pCAF histone acetyltransferases were administered alongside deacetylase inhibitors. We detected that SIRT2 and FOXM1 physically interacted, and SIRT2 deacetylated FOXM1 in vitro. SIRT2 overexpression led to a significant decrease while knockdown of SIRT2 increased the FOXM1 expression in HCT116 human colon carcinoma cells. In the analysis of 90 human colorectal cancer samples, high SIRT2 expression was observed in about 49% of colorectal cancer, intermediate in 29%, and low or no staining in 22%. Strong SIRT2 expression was found to be negatively associated with the FOXM1 staining in our clinical cohort. This study reveals a molecular interaction and association between SIRT2 and FOXM1 expression in colon cancer cell lines and human colon cancer samples, and suggests that targeting SIRT2 activity using small molecule modulators may be a promising therapeutic approach for colorectal cancer.

Lysine Acetyltransferase TIP60 Restricts Nerve Injury by Activating IKKβ/SNAP23 Axis-Mediated Autophagosome-Lysosome Fusion in Alzheimer's Disease.

The hyperphosphorylation of Tau protein is considered an important cause of neuronal degeneration in Alzheimer's disease (AD). The disruption of neuronal histone acetylation homeostasis mediated by Tip60 HAT is a common early event in neurodegenerative diseases, but the deeper regulatory mechanism on β-amyloid peptide (Aβ)-induced neurotoxicity and autophagic function in AD is still unclear. AD models were established both in APP/PS1 mice and Aβ1-42-treated SH-SY5Y cells. The Morris water maze test (MWM) was performed to examine mouse cognitive function. Neurological damage in the hippocampus was observed by hematoxylin-eosin (H&E), Nissl's, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), and NeuN staining. Autophagosome-lysosome fusion was detected by immunohistochemistry, immunofluorescence, and Lyso-Tracker Red staining. Cell viability and apoptosis were evaluated by CCK-8 assay and flow cytometry. The molecular interactions were verified by co-immunoprecipitation (Co-IP), dual luciferase assays, and ChIP detections. The RNA and autophagy-lysosome-related proteins were assessed by Western blot and RT-qPCR. TIP60 overexpression improved cognitive deficits and neurological damage and restored the impairment of autophagy-lysosomes fusion invivo. Similarly, the upregulation of TIP60 in Aβ1-42-treated SH-SY5Y cells suppressed neuronal apoptosis and tau phosphorylation through the activating autophagy-lysosome pathway. Mechanistically, TIP60 activated IKKβ transcription by promoting SOX4 acetylation, thus leading to the translocation of SNAP23 to STX17-contained autophagosomes. Moreover, the protective roles of TIP60 in neuron damage were abolished by the inhibition of SOX4/IKKβ signaling. Collectively, our results highlighted the potential of the TIP60 target for AD and provided new insights into the mechanisms underlying neuroprotection in this disorder.

Epigenetic Mechanisms of Aluminum-Induced Neurotoxicity and Alzheimer's Disease: A Focus on Non-Coding RNAs.

Aluminum (Al) is known to induce neurotoxic effects, potentially contributing to Alzheimer's disease (AD) pathogenesis. Recent studies suggest that epigenetic modification may contribute to Al neurotoxicity, although the mechanisms are still debatable. Therefore, the objective of the present study was to summarize existing data on the involvement of epigenetic mechanisms in Al-induced neurotoxicity, especially AD-type pathology. Existing data demonstrate that Al exposure induces disruption in DNA methylation, histone modifications, and non-coding RNA expression in brains. Alterations in DNA methylation following Al exposure were shown to be mediated by changes in expression and activity of DNA methyltransferases (DNMTs) and ten-eleven translocation proteins (TETs). Al exposure was shown to reduce histone acetylation by up-regulating expression of histone deacetylases (HDACs) and impair histone methylation, ultimately contributing to down-regulation of brain-derived neurotrophic factor (BDNF) expression and activation of nuclear factor κB (NF-κB) signaling. Neurotoxic effects of Al exposure were also associated with aberrant expression of non-coding RNAs, especially microRNAs (miR). Al-induced patterns of miR expression were involved in development of AD-type pathology by increasing amyloid β (Aβ) production through up-regulation of Aβ precursor protein (APP) and β secretase (BACE1) expression (down-regulation of miR-29a/b, miR-101, miR-124, and Let-7c expression), increasing in neuroinflammation through NF-κB signaling (up-regulation of miR-9, miR-125b, miR-128, and 146a), as well as modulating other signaling pathways. Furthermore, reduced global DNA methylation, altered histone modification, and aberrant miRNA expression were associated with cognitive decline in Al-exposed subjects. However, further studies are required to evaluate the contribution of epigenetic mechanisms to Al-induced neurotoxicity and/or AD development.

Lysine deacetylase inhibitors have low selectivity in cells and exhibit predominantly off-target effects.

Lysine deacetylases (KDACs or HDACs) are metal-dependent enzymes that regulate lysine acetylation, a post-translational modification that is present on thousands of human proteins, essential for many cellular processes, and often misregulated in diseases. The selective inhibition of KDACs would allow for understanding of the biological roles of individual KDACs and therapeutic targeting of individual enzymes. Recent studies have suggested that purportedly specific KDAC inhibitors have significant off-target binding, but the biological consequences of off-target binding were not evaluated. We compared the effects of treatment with two of the reportedly most KDAC-selective inhibitors, Tubastatin A and PCI-34051, in HT1080 cells in which the endogenous KDAC6 or KDAC8 gene has been mutated to inactivate enzyme catalysis while retaining enzyme expression. Genetic inactivation results in much stronger deacetylation defects on known targets compared to inhibitor treatment. Gene expression analysis revealed that both inhibitors have extensive and extensively overlapping off-target effects in cells, even at low inhibitor doses. Furthermore, Tubastatin A treatment led to increased histone acetylation, while inactivation of KDAC6 or KDAC8 did not. Genetic inactivation of KDAC6, but not KDAC8, impaired tumor formation in a xenograft model system, in contrast to previous reports with KDAC inhibitors suggesting the reverse. We conclude that the majority of observed biological effects of treatment with KDAC inhibitors are due to off-target effects rather than the intended KDAC inhibition. Developing a truly specific KDAC6 inhibitor could be a promising therapeutic avenue, but it is imperative to develop new inhibitors that selectively mimic genetic inactivation of individual KDACs.

Hypoxia-inducible factor-1α-deficient adipose-tissue macrophages produce the heat to mediate lipolysis of white adipose tissue through uncoupling protein-1

BackgroundUncoupling protein 1 (UCP1) is a proton uncoupler located across the mitochondrial membrane generally involved in thermogenesis of brown adipose tissues. Although UCP1 is known to be strongly expressed in brown adipocytes, recent evidence suggest that white adipocytes can also express UCP1 under certain circumstances such as cold- or β-adrenergic receptor-stimulation, allowing them to acquire brown adipocyte-like features thereby becoming 'beige’ adipocytes.ResultsIn this study, we report that UCP1 can be expressed in adipose-tissue macrophages (ATM) lacking functional hypoxia-inducible factor-1 (HIF-1) and this does not require cold- nor β-adrenergic receptor activation. By using myeloid-specific Hif-1α knockout (KO) mice, we observed that these mice were protected from diet-induced obesity and exhibited an improved thermogenic tolerance upon cold challenge. ATM isolated from white adipose tissues (WAT) of these mice fed with high fat diet exhibited significantly higher M2-polarization, decreased glycolysis, increased mitochondrial functions and acetyl-CoA levels, along with increased expression of Ucp1, peroxisome proliferator activated receptor-gamma co-activator-1a, and others involved in histone acetylation. Consistent with the increased Ucp1 gene expression, these ATM produced a significant amount of heat mediating lipolysis of co-cultured adipocytes liberating free fatty acid. Treating ATM with acetate, a substrate for acetyl-CoA synthesis was able to boost the heat production in wild-type or Hif-1α-deficient but not UCP1-deficient macrophages, indicating that UCP1 was necessary for the heat production in macrophages. Lastly, we observed a significant inverse correlation between the number of UCP1-expressing ATM in WAT and the body mass index of human individuals.ConclusionsUCP1-expressing ATM produce the heat to mediate lipolysis of adipocytes, indicating that this can be a novel strategy to treat and prevent diet-induced obesity.

Epigenetic DNA Methylation and Protein Homocysteinylation: Key Players in Hypertensive Renovascular Damage

Hypertension has been a threat to the health of people, the mechanism of which, however, remains poorly understood. It is clinically related to loss of nephron function, glomerular sclerosis, or necrosis, resulting in renal functional declines. The mechanisms underlying hypertension’s development and progression to organ damage, including hypertensive renal damage, remain to be fully elucidated. As a developing approach, epigenetics has been postulated to elucidate the phenomena that otherwise cannot be explained by genetic studies. The main epigenetic hallmarks, such as DNA methylation, histone acetylation, deacetylation, noncoding RNAs, and protein N-homocysteinylation have been linked with hypertension. In addition to contributing to endothelial dysfunction and oxidative stress, biologically active gases, including NO, CO, and H2S, are crucial regulators contributing to vascular remodeling since their complex interplay conducts homeostatic functions in the renovascular system. Importantly, epigenetic modifications also directly contribute to the pathogenesis of kidney damage via protein N-homocysteinylation. Hence, epigenetic modulation to intervene in renovascular damage is a potential therapeutic approach to treat renal disease and dysfunction. This review illustrates some of the epigenetic hallmarks and their mediators, which have the ability to diminish the injury triggered by hypertension and renal disease. In the end, we provide potential therapeutic possibilities to treat renovascular diseases in hypertension.

HIV-1 latency reversal agent boosting is not limited by opioid use.

Opioid use may impact the HIV-1 reservoir and its reversal from latency. We studied forty-seven virally suppressed people with HIV (PWH) and observed that lower concentration of HIV-1 latency reversal agents (LRA), used in combination with small molecules that did not reverse latency, synergistically increased the magnitude of HIV-1 re-activation ex vivo, regardless of opioid use. This LRA boosting, which combined a Smac mimetic or low-dose protein kinase C agonist with histone deacetylase inhibitors, generated significantly more unspliced HIV-1 transcription than phorbol 12-myristate 13-acetate (PMA) with ionomycin (PMAi), the maximal known HIV-1 reactivator. LRA boosting associated with greater histone acetylation, modulated surface activation-induced markers, and altered T cell production of TNFα, IL-2, and IFNγ. HIV-1 reservoirs in PWH contained unspliced and polyadenylated (polyA) virus mRNA, the ratios of which were greater in resting than total CD4+ T cells and correct to 1:1 with PMAi exposure. We characterized treated suppressed HIV-1 infection as a period of inefficient, not absent, virus transcription. Multiply spliced HIV-1 transcripts and virion production did not consistently increase with LRA boosting, suggesting the presence of a persistent post-transcriptional block. LRA boosting can be leveraged to probe mechanisms of an effective cellular HIV-1 latency reversal program.

Unraveling the molecular mechanism of FgGcn5 inhibition by phenazine-1-carboxamide: combined in silico and in vitro studies.

Fusarium head blight (FHB), mainly caused by Fusarium graminearum (F. graminearum), remains a devastating disease worldwide. The histone acetyltransferase Gcn5 plays a crucial role in epigenetic regulation. Aberrant Gcn5 acetylation activity can result in serious impacts such as impaired growth and development in organisms. The secondary metabolite phenazine-1-carboxamide (PCN) inhibits F. graminearum by blocking the acetylation process of Gcn5 (FgGcn5), and is currently used to control FHB. However, the molecular basis of acetylation inhibition by PCN remains to be further explored. Our molecular dynamics simulations revealed that PCN binds to the cleft in FgGcn5 where histone H3 is bound, with key amino acid residues including Leu96 (L96), Arg121 (R121), Phe133 (F133), Tyr169 (Y169), and Tyr201 (Y201), preventing FgGcn5 from binding to histone H3 and affecting histone H3 from being acetylated. Experimental validation of key amino acid mutations further confirmed the impact of these mutations on the interaction of FgGcn5 with PCN and histone H3 peptide. In summary, our study sheds light on the mechanism by which PCN inhibits the acetylation function of FgGcn5, providing a foundation for the development of drugs or fungicides targeting histone acetyltransferases. © 2024 Society of Chemical Industry.

Current Status of Immunotherapy in Management of Small Bowel Neuroendocrine Tumors.

This study aims to present the current landscape of immunotherapy in the management of small bowel neuroendocrine tumors and identify ongoing and future targets for improved response. Somatostatin analogs and mTOR inhibitors remain cornerstones of non-surgical treatment, and applications of PRRT in SBNET are promising. Several efforts to replicate the success of immunotherapies in other solid tumors have been attempted in SBNET, with limited responses observed with current immune targets, such as PD-1/PD-L1 and CTLA-4. Epigenetic analyses have suggested a potential role for methylation and histone acetylation in SBNET tumorigenesis that warrant greater exploration. While the incidence of SBNET continues to increase, the number of effective therapies is few. Further elucidation of targetable components of the SBNET immune microenvironment with greater modulatory effects is necessary to improve outcomes in this growing patient population.

Epigenetic modulation of vascular calcification: Looking for comprehending the role of sirt1 and histone acetylation in VSMC phenotypic transition

In light of the complex origins of ectopic vascular calcification and its significant health implications, this study offers a comprehensive exploration of the molecular dynamics governing vascular smooth muscle cells (VSMCs). Focusing on epigenetic modulation, we investigate the transition from a contractile to a calcifying phenotype in VSMCs, with an emphasis on understanding the role of SIRT1. For this purpose, a single batch of human aortic SMCs, used at a specified passage number to maintain consistency, was subjected to calcium and phosphate overload for up to 72 h. Our findings, validated through RT q-PCR, Western blot, immunofluorescence, and DNA methylation analyses, reveal a complex interplay between acetyltransferases and deacetylases during this phenotypic transition. We highlight HAT1A's critical role in histone acetylation regulation and the involvement of HDACs, as evidenced by subcellular localization studies. Moreover, we demonstrate the modulation of SIRT1 expression, a class III deacetylase, during VSMC calcification, underscoring the influence of DNA methylation in this process. Importantly, the study addresses previously unexplored aspects of the dynamic protein expression patterns observed, providing insight into the counterintuitive expressions of key proteins such as Runx2 and osterix. This research underscores the significant impact of epigenetic mechanisms, particularly the modulation of SIRT1, in the transition from a contractile to a calcifying phenotype in VSMCs, offering potential avenues for further exploration in the context of vascular calcification.

Guanidinoacetic acid regulated postmortem muscle glycolysis associated with AMPK signaling and protein acetylation.

Antemortem stress accelerated muscle energy consumption in postmortem muscle. The objective of our study was to investigate the regulation of guanidinoacetic acid (GAA) administration on the postmortem glycolysis and protein acetylation in postmortem muscle of antemortem stress. Forty C57BL/6 male mice were chosen and randomly assigned to four treatment groups (A, B, C and D), each treatment consisted of 10 replicates. Mice in group B, C and D were treated with 0.05% GAA oral administration for 6 days. On the 7th day of the experiment, the mice in group A and B were injected with saline, and mice in group C and D were injected with 5-aminoimidazole-4-carboxamide1-β-D-ribofuranoside (AICAR,50 μg/g body weight) and a combined injection with AICAR (50 μg/g body weight) and histone acetylase inhibitor Ⅱ (HAT Ⅱ,185 μg/g body weight), respectively. The results showed that the values of pH45min and pH24h of postmortem muscle in GAA administration were higher than those in the control group. However, the opposite result was observed in AICAR group. Moreover, the activities of acetone kinase, hexokinase and fruc-tose-2,6-diphosphatase, combined with the protein abundance of phosphorylated liver kinase, phosphorylated AMPKα2 and total acetylated protein were all decreased by GAA administration and HAT Ⅱ treatment. Taken together, AMPK signaling and protein acetylation could mediate the regulation of GAA administration on postmortem glycolysis of antemortem stress-muscle.

Epigenetic modulation of sirt1 and sirt6 in cardiovascular diseases: unraveling autophagy regulation and endothelial function

Abstract Background Heart failure (HF) and cardiovascular diseases (CVD) still represent major causes of death. Dysmetabolic conditions led by epigenetic alterations play a major role as CVD triggers, expecially those related to the modulation and control of autophagy during the remodelling in HF. Accordingly, several studies have strengthened the role of epigenetics in regulating both cardiac/endothelial phenotype and function, demonstrating how sirtuins, a well-acknowledged family of histone deacetylase, can conjunct the control of cardiac fibrosis, angiogenesis and induction of autophagy. However, this link remains to be fully clarified and explored. Thus, novel drugs targeting autophagy trough epigenetic mechanisms are considered appealing as targets from a pharmacological standpoint in CVD. Purpose This project aims to develop and test two epigenetic modulators and allosteric activators targeting SIRT1 and -6 to further elucidate their role in autophagy regulation and in cardiac/endothelial biology. Methods Chemical synthesis of SIRT1 and SIRT6 activator isoform (SRT2104 and MDL800). Evaluation of epigenetic modulation (H3 histone acetylation H3K9) of endothelial cells (HUVEC). HUVEC survival, angiogenic and autophagy activity were assessed undergo hyperglycemic or hypoxic stress, co-treatment with the selected compounds. Results The specific activator of SIRT-1 (SRT2104) and SIRT-6 (MDL800) show epigenetic activity as they induce the deacetylation of histone H3 on lysine 9. Endothelial cell viability is not influenced by the treatment with both modulators in hyperglycemia and upon hypoxic condition. In HUVEC cultures underwent to hyperglycemia-based stress, both molecules can activate autophagy with an increase in LC3 II protein (1,4-fold HG SRT2104 and 2,8-fold HG MDL800), compared to control.The treatment with SRT2104 enhances HUVEC tube formation, suggesting the increased functional angiogenic ability even in presence of high levels of glucose. Interestingly, the treatment with SRT2104 impacts the transcriptional levels of other members of the sirtuins family, by increasing SIRT-2, 3 and 5. In conclusion, the epigenetic activators SRT2104 and MDL800 have a beneficial effect on endothelial cells by enhancing the autophagic process and stimulate neoangiogenesis.The implementation of these results will attempt to understand to what extent epigenetic drugs such as sirtuin activators, could boost the more pleiotropic and less targeted effects of the current cardiovascular drugs, and to evaluate their functional and phenotype-driven drug refinement.

ZmSCE1a positively regulates drought tolerance by enhancing the stability of ZmGCN5.

Drought stress impairs plant growth and poses a serious threat to maize (Zea mays) production and yield. Nevertheless, the elucidation of the molecular basis of drought resistance in maize is still uncertain. In this study, we identified ZmSCE1a, a SUMO E2-conjugating enzyme, as a positive regulator of drought tolerance in maize. Molecular and biochemical assays indicated that E3 SUMO ligase ZmMMS21 acts together with ZmSCE1a to SUMOylate histone acetyltransferase complexes (ZmGCN5-ZmADA2b). SUMOylation of ZmGCN5 enhances its stability through the 26S proteasome pathway. Furthermore, ZmGCN5-overexpressing plants showed drought tolerance performance. It alleviated accumulation, malondialdehyde content, and ion permeability. What's more, the transcripts of stress-responsive genes and abscisic acid (ABA)-dependent genes were also significantly upregulated in ZmGCN5-overexpressing plants under drought stress. Overexpression of ZmGCN5 enhanced drought-induced ABA production in seedlings. Taken together, our results indicate that ZmSCE1a enhances the stability of ZmGCN5, thereby alleviating drought-induced oxidative damage and enhancing drought stress response in maize.

Mitochondrial fatty acid oxidation drives senescence.

Cellular senescence is a stress-induced irreversible cell cycle arrest involved in tumor suppression and aging. Many stresses, such as telomere shortening and oncogene activation, induce senescence by damaging nuclear DNA. However, the mechanisms linking DNA damage to senescence remain unclear. Here, we show that DNA damage response (DDR) signaling to mitochondria triggers senescence. A genome-wide small interfering RNA screen implicated the outer mitochondrial transmembrane protein BNIP3 in senescence induction. We found that BNIP3 is phosphorylated by the DDR kinase ataxia telangiectasia mutated (ATM) and contributes to an increase in the number of mitochondrial cristae. Stable isotope labeling metabolomics indicated that the increase in cristae enhances fatty acid oxidation (FAO) to acetyl-coenzyme A (acetyl-CoA). This promotes histone acetylation and expression of the cyclin-dependent kinase inhibitor p16INK4a. Notably, pharmacological activation of FAO alone induced senescence both in vitro and in vivo. Thus, mitochondrial energy metabolism plays a critical role in senescence induction and is a potential intervention target to control senescence.

Butyrate Inhibits the HDAC8/NF-κB Pathway to Enhance Slc26a3 Expression and Improve the Intestinal Epithelial Barrier to Relieve Colitis.

Dietary fiber is known to promote the production of short-chain fatty acids (SCFAs) by gut bacteria, which can enhance intestinal epithelial barrier function and ameliorate intestinal inflammation in patients with inflammatory bowel disease (IBD). Interestingly, some IBD patients show reduced expression of solute carrier family member 3 (Slc26a3) in intestinal epithelial cells. The objective of this research was to investigate the interaction between SCFAs and Slc26a3 during colitis and assess how this interaction affects intestinal epithelial barrier function. We showed that butyrate alleviated colonic inflammation in a dose-dependent manner in a dextran sulfate sodium salt (DSS)-induced colitis model. Consistent with this, butyrate increased Slc26a3 and tight junction protein levels. In addition, butyrate inhibited histone deacetylase (HDAC) levels and significantly increased the expression of Slc26a3 by the acetylation of histones in Caco-2BBe cells. The utilization of a pan-HDAC inhibitor or inhibitors specific to certain classes of HDACs revealed that butyrate primarily suppressed HDAC8 to blunt the NF-κB pathways and enhance the expression of Slc26a3. Notably, we demonstrated that HDAC8 activation counteracted the beneficial effect of butyrate in DSS-induced colitis. Therefore, we concluded that butyrate improves the expression of Slc26a3 via inhibition of the HDAC8/NF-κB pathway, leading to increased intestinal epithelial barrier function.

PACAP38 synergizes with irradiation to suppress the proliferation of multiple cancer cells via regulating SOX6/Wnt/β-catenin signaling

BackgroundPituitary adenylate cyclase-activating polypeptide (PACAP) 38 is an endogenous neuropeptide with diverse functions, notably its critical role in inhibiting tumor proliferation. Radiotherapy is an important step in the standard treatment modality of many tumors. Combining radiotherapy with therapeutic agents represents a new and promising trend aimed at enhancing radiation sensitivity and improving tumor treatment efficacy. However, the efficacy of PACAP38 combined with radiotherapy on tumors has not yet been studied.ObjectiveThis study aimed to investigate the impact of PACAP38, both independently and in combination with irradiation, on glioma and breast cancer cells, while elucidating the underlying mechanisms involved.MethodsWe investigated the impact of PACAP38 independently and combined it with irradiation on glioma and breast cancer cells in vitro through cell counting kit-8, clonogenic formation, Edu assays, and in vivo through a xenograft tumor model. We further explored the molecular mechanisms underlying the inhibitory effects of PACAP38 on tumors using RNA sequencing, western blotting assay, immunohistochemistry, and immunofluorescence analysis. Further investigation of gene function and the downstream mechanism was carried out through small interfering RNA and overexpression lentivirus targeting the SRY-related high-mobility group box 6 (SOX6) gene and western blotting assay.ResultsOur findings revealed that PACAP38 could effectively synergize with radiation to suppress the proliferation of glioma and breast cancer cells in vivo and in vitro. Molecular studies revealed that the inhibitory effect of PACAP38 on tumor cell proliferation was mediated by upregulating SOX6 protein expression through histone acetylation, thereby inhibiting the Wnt-β-catenin signaling pathway.ConclusionPACAP38 synergizes with irradiation to suppress the proliferation of multiple cancer cells via regulating SOX6/Wnt/β-catenin signaling. This combination may represent a promising therapeutic strategy for cancer treatment, potentially improving outcomes for patients undergoing radiotherapy.

Immunohistochemical Evaluation of p300, H2AacK5 and H3AcK27 in Odontogenic Cysts and Tumors.

The acetylation of histones H2A on lysine 5 (H2AacK5) and H3 on lysine 27 (H3AcK27) modulate several cellular mechanisms through the p300 enzyme in pathological lesions; however, their role in odontogenic lesions has not been addressed. This study aims to evaluate the immunoexpression of p300, H2AacK5, and H3AcK27 in samples of ameloblastoma (AMB) (n = 30), odontogenic keratocyst (OK) (n = 15), adenomatoid odontogenic tumor (AOT) (n = 10), odontogenic fibroma (OF) (n = 8), calcifying odontogenic cyst (COC) (n = 8), odontogenic myxoma (MIX) (n = 10), and ameloblastic fibroma (AF) (n = 06). The percentage of p300-positive cells was higher in AOT and decreased in COC, OK, AMB, AF, OF, and MIX. H2AacK5-positive cells were higher in AF and decreased in AOT, COC, OK, OF, AMB, and MIX, whereas H3acK27-positive cells were higher in AOT and decreased in COC, OK, AF, OF, AMB, and MIX. The expression of these proteins was higher in nonaggressive lesions in comparison to aggressive lesions. There was a positive correlation between p300 and H2AacK5, and H3acK27 in AMB, MIX, and OF, whereas there was a positive correlation between p300 and H2AacK5 in AOT and COC. The histone acetylation may be involved in the biological behavior of these lesions, which could be used to improve their diagnosis and treatment.

Spt5 orchestrates cryptic transcript suppression and transcriptional directionality

Spt5 is a well-conserved factor that manipulates multiple stages of transcription from promoter-proximal pausing (PPP) to termination. Recent studies have revealed an unexpected increase of antisense transcripts near promoters in cells expressing mutant Spt5. Here, we identify Spt5p-restricted intragenic antisense transcripts and their close relationship with sense transcription in yeast. We confirm that Spt5 CTR phosphorylation is also important to retain Spt5’s facility to regulate antisense transcription. The genes whose antisense transcription is strongly suppressed by Spt5p share strong endogenous sense transcription and weak antisense transcription, and this pattern is conserved in humans. Mechanistically, we found that Spt5p depletion increased histone acetylation to initiate intragenic antisense transcription by altering chromatin structure. We additionally identified termination factors that appear to be involved in the ability of Spt5p to restrict antisense transcription. By unveiling a new role of Spt5 in finely balancing the bidirectionality of transcription, we demonstrate that Spt5-mediated suppression of DSIF complex regulated-unstable transcripts (DUTs) is essential to sustain the accurate transcription by RNA polymerase II.