PI3K/mTOR mediate mitogen-dependent HDAC1 phosphorylation in breast cancer: a novel regulation of estrogen receptor expression

Accurate network pharmacology and novel ingredients formula of herbal targeting estrogen signaling for psoriasis intervention

ETHNOPHARMACOLOGICAL RELEVANCE

As a common chronic inflammatory skin disease, psoriasis is incompletely understood and brings a lot of distress to patients. The estrogen signaling pathway has been implicated in its pathogenesis, making it a potential therapeutic target. Si Cao Formula (SCF) has demonstrated promise in treating psoriasis clinically. However, its molecular mechanisms concerning psoriasis remain largely unexplored.

AIM OF THE STUDY

To elucidate the underlying mechanisms of the action of SCF on psoriasis.

MATERIALS AND METHODS

Active ingredients were identified by LC-MS/MS. After the treatment with SCF, the exploration of differentially expressed proteins (DEPs) were conducted using tandem mass tag (TMT)-based quantitative proteomics analysis. By GO/KEGG, WikiPathways and network pharmacology, core signaling pathway and protein targets were explored. Consequently, major signaling pathway and protein targets were validated by RT-qPCR, immunoblotting and immunofluorescence. Based on Lipinski's Rule of Five rules and molecular docking, 8 active compounds were identified that acted on the core targets.

RESULTS

41 compounds of SCF and 848 specific targets of these compounds were identified. There were 570 DEPs between IMQ (Imiquimod) and IMQ + SCF group, including 279 up-regulated and 304 down-regulated proteins. GO/KEGG, WikiPathways and network pharmacology revealed estrogen signaling pathway as the paramount pathways, through which SCF functioned on psoriasis. We further show novel ingredients formula of SCF contributes to estrogen signaling intervention, including liquiritin, parvisoflavone B, glycycoumarin, 8-prenylluteone, licochalcone A, licochalcone B, oxymatrine, and 13-Hydroxylupanine, where targeting MAP2K1, ILK, HDAC1 and PRKACA, respectively. Molecular docking proves that they have good binding properties.

CONCLUSION

Our results provide an in-depth view of psoriasis pathogenesis and herbal intervention, which expands our understanding of the systemic pharmacology to reveal the multiple ingredients and multiple targets of SCF and focus on one pathway (estrogen signaling pathway) may be a novel therapeutic strategy for psoriasis treatment of herbal medicine.

Identifying Key Regulatory Genes in Drug Resistance Acquisition: Modeling Pseudotime Trajectories of Breast Cancer Single-Cell Transcriptome

Single-cell RNA-sequencing (scRNA-seq) technology has provided significant insights into cancer drug resistance at the single-cell level. However, understanding dynamic cell transitions at the molecular systems level remains limited, requiring a systems biology approach. We present an approach that combines mathematical modeling with a pseudotime analysis using time-series scRNA-seq data obtained from the breast cancer cell line MCF-7 treated with tamoxifen. Our single-cell analysis identified five distinct subpopulations, including tamoxifen-sensitive and -resistant groups. Using a single-gene mathematical model, we discovered approximately 560-680 genes out of 6000 exhibiting multistable expression states in each subpopulation, including key estrogen-receptor-positive breast cancer cell survival genes, such as RPS6KB1. A bifurcation analysis elucidated their regulatory mechanisms, and we mapped these genes into a molecular network associated with cell survival and metastasis-related pathways. Our modeling approach comprehensively identifies key regulatory genes for drug resistance acquisition, enhancing our understanding of potential drug targets in breast cancer.

Research Progress on the Correlation between Acetaldehyde Dehydrogenase 2 and Hepatocellular Carcinoma Development

Hepatocellular carcinoma (HCC) is the predominant pathologic type of primary liver cancer. It is a malignant tumor of liver epithelial cells. There are many ways to treat HCC, but the survival rate for HCC patients remains low. Therefore, understanding the underlying mechanisms by which HCC occurs and develops is critical to explore new therapeutic targets. Aldehyde dehydrogenase 2 (ALDH2) is an important player in the redox reaction of ethanol with endogenous aldehyde products released by lipid peroxidation. Increasing evidence suggests that ALDH2 is a crucial regulator of human tumor development, including HCC. Therefore, clarifying the relationship between ALDH2 and HCC is helpful for formulating rational treatment strategies. This review highlights the regulatory roles of ALDH2 in the development of HCC, elucidates the multiple potential mechanisms by which ALDH2 regulates the development of HCC, and summarizes the progress of research on ALDH2 gene polymorphisms and HCC susceptibility. Meanwhile, we envision viable strategies for targeting ALDH2 in the treatment of HCC SIGNIFICANCE STATEMENT: Numerous studies have aimed to explore novel therapeutic targets for HCC, and ALDH2 has been reported to be a critical regulator of HCC progression. This review discusses the functions, molecular mechanisms, and clinical significance of ALDH2 in the development of HCC and examines the prospects of ALDH2-based therapy for HCC.

Beyond controlling cell size: functional analyses of S6K in tumorigenesis

As a substrate and major effector of the mammalian target of rapamycin complex 1 (mTORC1), the biological functions of ribosomal protein S6 kinase (S6K) have been canonically assigned for cell size control by facilitating mRNA transcription, splicing, and protein synthesis. However, accumulating evidence implies that diverse stimuli and upstream regulators modulate S6K kinase activity, leading to the activation of a plethora of downstream substrates for distinct pathobiological functions. Beyond controlling cell size, S6K simultaneously plays crucial roles in directing cell apoptosis, metabolism, and feedback regulation of its upstream signals. Thus, we comprehensively summarize the emerging upstream regulators, downstream substrates, mouse models, clinical relevance, and candidate inhibitors for S6K and shed light on S6K as a potential therapeutic target for cancers.

The Role of Dexmedetomidine in Tumor-Progressive Factors in the Perioperative Period and Cancer Recurrence: A Narrative Review

Dexmedetomidine, a specific α2 adrenergic receptor agonist, is highly frequently used in the perioperatively for its favorable pharmacology, such as mitigating postoperative cognitive dysfunction. Increasing attention has been recently focused on the effect of whether dexmedetomidine influences cancer recurrence, which urges the discussion of the role of dexmedetomidine in tumor-progressive factors. The pharmacologic characteristics of dexmedetomidine, the tumor-progressive factors in the perioperative period, and the relationships between dexmedetomidine and tumor-progressive factors were described in this review. Available evidence suggests that dexmedetomidine could reduce the degree of immune function suppression, such as keeping the number of CD3+ cells, NK cells, CD4+/CD8+ ratio, and Th1/Th2 ratio stable and decreasing the level of proinflammatory cytokine (interleukin 6 and tumor necrosis factor-alpha) during cancer operations. However, dexmedetomidine exhibits different roles in cell biological behavior depending on cancer cell types. The conclusions on whether dexmedetomidine would influence cancer recurrence could not be currently drawn for the lack of strong clinical evidence. Therefore, this is still a new area that needs further exploration.

HDACs and the epigenetic plasticity of cancer cells: Target the complexity

Cancer cells must adapt to the hostile conditions of the microenvironment in terms of nutrition, space, and immune system attack. Mutations of DNA are the drivers of the tumorigenic process, but mutations must be able to hijack cellular functions to sustain the spread of mutant genomes. Transcriptional control is a key function in this context and is controlled by the rearrangement of the epigenome. Unlike genomic mutations, the epigenome of cancer cells can in principle be reversed. The discovery of the first epigenetic drugs triggered a contaminating enthusiasm. Unfortunately, the complexity of the epigenetic machinery has frustrated this enthusiasm. To develop efficient patient-oriented epigenetic therapies, we need to better understand the nature of this complexity. In this review, we will discuss recent advances in understanding the contribution of HDACs to the maintenance of the transformed state and the rational for their selective targeting.

Vorinostat in autophagic cell death: A critical insight into autophagy-mediated, -associated and -dependent cell death for cancer prevention

Histone deacetylases (HDACs) inhibit the acetylation of crucial autophagy genes, thereby deregulating autophagy and autophagic cell death (ACD) and facilitating cancer cell survival. Vorinostat, a broad-spectrum pan-HDAC inhibitor, inhibits the deacetylation of key autophagic markers and thus interferes with ACD. Vorinostat-regulated ACD can have an autophagy-mediated, -associated or -dependent mechanism depending on the involvement of apoptosis. Molecular insights revealed that hyperactivation of the PIK3C3/VPS34-BECN1 complex increases lysosomal disparity and enhances mitophagy. These changes are followed by reduced mitochondrial biogenesis and by secondary signals that enable superactivated, nonselective or bulk autophagy, leading to ACD. Although the evidence is limited, this review focuses on molecular insights into vorinostat-regulated ACD and describes critical concepts for clinical translation.

Network Analysis Identifies Regulators of Basal-Like Breast Cancer Reprogramming and Endocrine Therapy Vulnerability

Basal-like breast cancer is the most aggressive breast cancer subtype with the worst prognosis. Despite its high recurrence rate, chemotherapy is the only treatment for basal-like breast cancer, which lacks expression of hormone receptors. In contrast, luminal A tumors express ERα and can undergo endocrine therapy for treatment. Previous studies have tried to develop effective treatments for basal-like patients using various therapeutics but failed due to the complex and dynamic nature of the disease. In this study, we performed a transcriptomic analysis of patients with breast cancer to construct a simplified but essential molecular regulatory network model. Network control analysis identified potential targets and elucidated the underlying mechanisms of reprogramming basal-like cancer cells into luminal A cells. Inhibition of BCL11A and HDAC1/2 effectively drove basal-like cells to transition to luminal A cells and increased ERα expression, leading to increased tamoxifen sensitivity. High expression of BCL11A and HDAC1/2 correlated with poor prognosis in patients with breast cancer. These findings identify mechanisms regulating breast cancer phenotypes and suggest the potential to reprogram basal-like breast cancer cells to enhance their targetability. SIGNIFICANCE: A network model enables investigation of mechanisms regulating the basal-to-luminal transition in breast cancer, identifying BCL11A and HDAC1/2 as optimal targets that can induce basal-like breast cancer reprogramming and endocrine therapy sensitivity.

Topographic correlates of driver mutations and endogenous gene expression in pediatric diffuse midline gliomas and hemispheric high-grade gliomas

We evaluate the topographic distribution of diffuse midline gliomas and hemispheric high-grade gliomas in children with respect to their normal gene expression patterns and pathologic driver mutation patterns. We identified 19 pediatric patients with diffuse midline or high-grade glioma with preoperative MRI from tumor board review. 7 of these had 500 gene panel mutation testing, 11 patients had 50 gene panel mutation testing and one 343 gene panel testing from a separate institution were included as validation set. Tumor imaging features and gene expression patterns were analyzed using Allen Brain Atlas. Twelve patients had diffuse midline gliomas and seven had hemispheric high-grade gliomas. Three diffuse midline gliomas had the K27M mutation in the tail of histone H3 protein. All patients undergoing 500 gene panel testing had additional mutations, the most common being in ACVR1, PPM1D, and p53. Hemispheric high-grade gliomas had either TP53 or IDH1 mutation and diffuse midline gliomas had H3 K27M-mutation. Gene expression analysis in normal brains demonstrated that genes mutated in diffuse midline gliomas had higher expression along midline structures as compared to the cerebral hemispheres. Our study suggests that topographic location of pediatric diffuse midline gliomas and hemispheric high-grade gliomas correlates with driver mutations of tumor to the endogenous gene expression in that location. This correlation suggests that cellular state that is required for increased gene expression predisposes that location to mutations and defines the driver mutations within tumors that arise from that region.

EGFR phosphorylates HDAC1 to regulate its expression and anti-apoptotic function

HDAC1 is the prototypical human histone deacetylase (HDAC) enzyme responsible for catalyzing the removal of acetyl group from lysine residues on many substrate proteins. By deacetylating histones and non-histone proteins, HDAC1 has a profound effect on the regulation of gene transcription and many processes related to cell growth and cell death, including cell cycle progression, DNA repair, and apoptosis. Early studies reveal that, like most eukaryotic proteins, the functions and activities of HDAC1 are regulated by post-translational modifications. For example, serine phosphorylation of HDAC1 by protein kinase CK2 promotes HDAC1 deacetylase enzymatic activity and alters its interactions with proteins in corepressor complexes. Here, we describe an alternative signaling pathway by which HDAC1 activities are regulated. Specifically, we discover that EGFR activity promotes the tyrosine phosphorylation of HDAC1, which is necessary for its protein stability. A key EGFR phosphorylation site on HDAC1, Tyr72, mediates HDAC1's anti-apoptotic function. Given that HDAC1 overexpression and EGFR activity are strongly related with tumor progression and cancer cell survival, HDAC1 tyrosine phosphorylation may present a possible target to manipulate HDAC1 protein levels in future potential cancer treatment strategies.

Padhoc: a computational pipeline for pathway reconstruction on the fly

MOTIVATION

Molecular pathway databases represent cellular processes in a structured and standardized way. These databases support the community-wide utilization of pathway information in biological research and the computational analysis of high-throughput biochemical data. Although pathway databases are critical in genomics research, the fast progress of biomedical sciences prevents databases from staying up-to-date. Moreover, the compartmentalization of cellular reactions into defined pathways reflects arbitrary choices that might not always be aligned with the needs of the researcher. Today, no tool exists that allow the easy creation of user-defined pathway representations.

RESULTS

Here we present Padhoc, a pipeline for pathway ad hoc reconstruction. Based on a set of user-provided keywords, Padhoc combines natural language processing, database knowledge extraction, orthology search and powerful graph algorithms to create navigable pathways tailored to the user's needs. We validate Padhoc with a set of well-established Escherichia coli pathways and demonstrate usability to create not-yet-available pathways in model (human) and non-model (sweet orange) organisms.

AVAILABILITY AND IMPLEMENTATION

Padhoc is freely available at https://github.com/ConesaLab/padhoc.

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

EnDuo, a novel derivative of Endostar, inhibits the migration of colon cancer cells, suppresses matrix metalloproteinase-2/9 expression and impedes AKT/ERK activation

BACKGROUND/AIMS

Colon cancer remains a life-threating disease with increasing morbidity and mortality worldwide despite the advancement in modern medical treatment. Therefore, novel and effective anti-colon cancers drugs are urgently needed. In this study, we investigated the anti-metastatic property EnDuo, a modified version of Endostar, and the underlying mechanisms.

METHODS

Colon cancer cells were treated with different concentrations of EnDuo (50 μg/mL, 100 μg/mL, 200 μg/mL), and Endostar (100 μg/mL) as positive control. Cell Counting Kit-8 assay was performed to test the effect of EnDuo on cell viability. A scratch wound assay and transwell assay were employed to evaluate the relocation and motility of malignant colon cells following treatment with EnDuo. Western blot analysis was used to determine inhibitory effects of EnDuo by detecting the phosphorylation level of AKT and ERK proteins, and the expression of MMP-2 and MMP-9 proteins.

RESULTS

Our results showed that EnDuo impedes the migration of colon cancer cells in a dose-dependent manner. At the molecular level, EnDuo induced a significant reduction in the phosphorylation of AKT and ERK proteins, and inhibited the expression of MMP-2 and MMP-9 proteins.

CONCLUSIONS

Collectively, these results demonstrate that EnDuo exhibits a comparable anti-metastatic effect by suppressing the migration of colon cancer cells. Possibly, EnDuo interrupts the PI3K/AKT/ERK signaling pathway to arrest cell migration. Our study provides a novel insight to the potential clinical applications of EnDuo against colon cancers in the future.

Intrinsic and Extrinsic Factors Governing the Transcriptional Regulation of ESR1

Transcriptional regulation of ESR1, the gene that encodes for estrogen receptor α (ER), is critical for regulating the downstream effects of the estrogen signaling pathway in breast cancer such as cell growth. ESR1 is a large and complex gene that is regulated by multiple regulatory elements, which has complicated our understanding of how ESR1 expression is controlled in the context of breast cancer. Early studies characterized the genomic structure of ESR1 with subsequent studies focused on identifying intrinsic (chromatin environment, transcription factors, signaling pathways) and extrinsic (tumor microenvironment, secreted factors) mechanisms that impact ESR1 gene expression. Currently, the introduction of genomic sequencing platforms and additional genome-wide technologies has provided additional insight on how chromatin structures may coordinate with these intrinsic and extrinsic mechanisms to regulate ESR1 expression. Understanding these interactions will allow us to have a clearer understanding of how ESR1 expression is regulated and eventually provide clues on how to influence its regulation with potential treatments. In this review, we highlight key studies concerning the genomic structure of ESR1, mechanisms that affect the dynamics of ESR1 expression, and considerations towards affecting ESR1 expression and hormone responsiveness in breast cancer.

Early 5-HT6 receptor blockade prevents symptom onset in a model of adolescent cannabis abuse

Cannabis abuse during adolescence confers an increased risk for developing later in life cognitive deficits reminiscent of those observed in schizophrenia, suggesting common pathological mechanisms that remain poorly characterized. In line with previous findings that revealed a role of 5-HT6 receptor-operated mTOR activation in cognitive deficits of rodent developmental models of schizophrenia, we show that chronic administration of ∆9-tetrahydrocannabinol (THC) to mice during adolescence induces a long-lasting activation of mTOR in prefrontal cortex (PFC), alterations of excitatory/inhibitory balance, intrinsic properties of layer V pyramidal neurons, and long-term depression, as well as cognitive deficits in adulthood. All are prevented by administrating a 5-HT6 receptor antagonist or rapamycin, during adolescence. In contrast, they are still present 2 weeks after the same treatments delivered at the adult stage. Collectively, these findings suggest a role of 5-HT6 receptor-operated mTOR signaling in abnormalities of cortical network wiring elicited by THC at a critical period of PFC maturation and highlight the potential of 5-HT6 receptor antagonists as early therapy to prevent cognitive symptom onset in adolescent cannabis abusers.

Trichostatin A alleviated ovarian tissue damage caused by cigarette smoke exposure

Cigarette smoke (CS) has a negative impact on women's health and fertility. Studies have shown that histone deacetylases 1 and 2 (HDAC1/2) were involved in oocyte development. However, the roles of HDAC1/2 in ovarian toxicity caused by CS exposure and the therapeutic potential of trichostatin A (TSA, a HDAC inhibitor) for ovarian tissue damage have not been investigated. In this study, Female C57BL/6 mice were exposed to CS from six cigarettes mixed with indoor air for 120 min (one cigarette for 20 min) using a whole-body mainstream smoke exposure system twice daily for 30 days. TSA (0.6 mg/kg body weight) was injected intraperitoneally into mice in the Control + TSA group and CS + TSA group every two days for 30 days. We found that exposure to CS resulted in ovarian tissue damage and HDAC1/2 over-expression. TSA alleviated the structural changes of ovarian tissue induced by smoking and prevented the activation of HDAC1/2. Exposure to CS caused autophagy inhibition and pyroptosis activation. TSA treatment restored the expression of autophagy-associated proteins and decreased the levels of pyroptosis-related proteins induced by CS exposure. The TSA effect may be mediated by inhibition of HDAC1/2 involved in autophagy and pyroptosis process.

Distinct Roles of mTOR Targets S6K1 and S6K2 in Breast Cancer

The mechanistic target of rapamycin (mTOR) is a master regulator of protein translation, metabolism, cell growth and proliferation. It forms two complexes, mTOR complex 1 (mTORC1) and 2 (mTORC2). mTORC1 is frequently deregulated in many cancers, including breast cancer, and is an important target for cancer therapy. The immunosuppressant drug rapamycin and its analogs that inhibit mTOR are currently being evaluated for their potential as anti-cancer agents, albeit with limited efficacy. mTORC1 mediates its function via its downstream targets 40S ribosomal S6 kinases (S6K) and eukaryotic translation initiation factor 4E (eIF4E)-binding protein 1 (4E-BP1). There are two homologs of S6K: S6K1 and S6K2. Most of the earlier studies focused on S6K1 rather than S6K2. Because of their high degree of structural homology, it was generally believed that they behave similarly. Recent studies suggest that while they may share some functions, they may also exhibit distinct or even opposite functions. Both homologs have been implicated in breast cancer, although how they contribute to breast cancer may differ. The purpose of this review article is to compare and contrast the expression, structure, regulation and function of these two S6K homologs in breast cancer.

Transcription factor E2F4 is a positive regulator of milk biosynthesis and proliferation of bovine mammary epithelial cells

The transcription factor E2F4 is a key determinant of cell differentiation and cell-cycle progression, but its function and regulatory mechanism are not completely understood. Here, we report that E2F4 acts as a positive regulator of the biosynthesis of milk components and proliferation of bovine mammary epithelial cells (BMECs). Overexpression of E2F4 in BMECs resulted in the upregulation of β-casein, triglyceride, and lactose levels and increased cell proliferation, whereas E2F4 knockdown by small interfering RNA had the opposite effects. We further detected that overexpression of E2F4 significantly increased the messenger RNA expression of mTOR, SREBP-1c, and Cyclin D1, and increased protein levels of SREBP-1c, and Cyclin D1, and the ratio of p-mTOR/mTOR, whereas E2F4 knockdown had the opposite effects. E2F4 was almost entirely located in the nucleus, and we further identified, via ChIP-qPCR analysis, that mTOR, SREBP-1c, and Cyclin D1 were E2F4 target genes, and exogenous administration of methionine, leucine, β-estradiol, and prolactin markedly increased the protein levels of E2F4 and its binding to the promoters of these three genes. In summary, our data reveal that E2F4 responds to extracellular stimuli and regulates the expression of mTOR, SREBP-1c, and Cyclin D1 for milk biosynthesis and proliferation of BMECs.

Metformin Promotes Anti-tumor Biomarkers in Human Endometrial Cancer Cells

Metformin (MET) is increasingly implicated in reducing the incidence of multiple cancer types in patients with diabetes. However, similar effects of MET in non-diabetic women with endometrial cancer (EC) remain unknown. In a pilot study, obese non-diabetic women diagnosed with type 1, grade 1/2 EC, and consenting to participate were randomly assigned to receive MET or no MET (control (CON)) during the pre-surgical window between diagnosis and hysterectomy. Endometrial tumors obtained at surgery (MET, n = 4; CON, n = 4) were analyzed for proliferation (Ki67), apoptosis (TUNEL), and nuclear expression of ERα, PGR, PTEN, and KLF9 proteins in tumor glandular epithelial (GE) and stromal (ST) cells. The percentages of immunopositive cells for PGR and for KLF9 in GE and for PTEN in ST were higher while those for ERα in GE but not ST were lower, in tumors of MET vs. CON patients. The numbers of Ki67- and TUNEL-positive cells in tumor GE and ST did not differ between groups. In human Ishikawa endometrial cancer cells, MET treatment (60 μM) decreased cell numbers and elicited distinct temporal changes in ESR1, KLF9, PGR, PGR-B, KLF4, DKK1, and other tumor biomarker mRNA levels. In the context of reduced KLF9 expression (by siRNA targeting), MET rapidly amplified PGR, PGR-B, and KLF4 transcript levels. Our findings suggest that MET acts directly in EC cells to modify steroid receptor expression and signaling network and may constitute a preventative strategy against EC in high-risk non-diabetic women.

Epigenetic regulation of prostate cancer

Prostate cancer is (PCa) the second leading cause of cancer death in males in the United State, with 174,650 new cases and 31,620 deaths estimated in 2019. It has been documented that epigenetic deregulation such as histone modification and DNA methylation contributes to PCa initiation and progression. EZH2 (enhancer of zeste homolog 2), the catalytic subunit of the Polycomb Repressive Complex (PRC2) responsible for H3K27me3 and gene repression, has been identified as a promising target in PCa. In addition, overexpression of other epigenetic regulators such as DNA methyltransferases (DNMT) is also observed in PCa. These epigenetic regulators undergo extensive post-translational modifications, in particular, phosphorylation. AKT, CDKs, PLK1, PKA, ATR and DNA-PK are the established kinases responsible for phosphorylation of various epigenetic regulators.

mTOR/HDAC1 Crosstalk Mediated Suppression of ADH1A and ALDH2 Links Alcohol Metabolism to Hepatocellular Carcinoma Onset and Progression in silico

Hepatocellular carcinoma (HCC) is ranked the third deadliest cancer worldwide whose molecular pathogenesis is not fully understood. Although deregulated metabolic pathways have been implicated in HCC onset and progression, the mechanisms triggering this metabolic imbalance are yet to be explored. Here, we identified a gene signature coding catabolic enzymes (Cat-GS) involved in key metabolic pathways like amino acid, lipid, carbohydrate, drug, and retinol metabolism as suppressed in HCC. A higher expression of deregulated Cat-GS is associated with good survival and less aggressive disease state in HCC patients. On the other hand, we identified mTOR signaling as a key determinant in HCC onset and progression, whose hyperactivation is found associated with poor survival and aggressive disease state in HCC patients. Next, out of Cat-GS, we established two key regulators of alcohol metabolism, alcohol dehydrogenase 1A (ADH1A) and aldehyde dehydrogenase 2 (ALDH2), as being transcriptionally suppressed by histone deacetylase 1 (HDAC1) at the downstream of mTORC1 signaling. Suppressed ADH1A and ALDH2 expression aligns well with HCC-specific molecular profile and can efficiently predict disease onset and progression, whereas higher ADH1A and ALDH2 expression is associated with good survival and less aggressive disease state in HCC patients. Overall, our in silico findings suggest that transcriptional suppression of alcohol metabolism regulators, ADH1A and ALDH2, at the downstream of mTOR signaling is, in part, responsible for triggering oncogenic transformation of hepatocytes resulting in disease onset and progression in HCC.

Effects of the pesticide chlorpyrifos on breast cancer disease. Implication of epigenetic mechanisms

Chlorpyrifos (CPF) is an organophosphorus pesticide used for agricultural pest control all over the world. We have previously demonstrated that environmental concentrations of this pesticide alter mammary gland histological structure and hormonal balance in rats chronically exposed. In this work, we analyzed the effects of CPF on mammary tumors development. Our results demonstrated that CPF increases tumor incidence and reduces latency of NMU-induced mammary tumors. Although no changes were observed in tumor growth rate, we found a reduced steroid hormone receptor expression in the tumors of animals exposed to the pesticide. Moreover, we analyzed the role of epigenetic mechanisms in CPF effects. Our results indicated that CPF alters HDAC1 mRNA expression in mammary gland, although no changes were observed in DNA methylation. In summary, we demonstrate that the exposure to CPF promotes mammary tumors development with a reduced steroid receptors expression. It has also been found that CPF affects HDAC1 mRNA levels in mammary tissue pointing that CPF may act as a breast cancer risk factor.

The next generation of PI3K-Akt-mTOR pathway inhibitors in breast cancer cohorts

The PI3K/Akt/mTOR pathway plays a role in various oncogenic processes in breast cancer and key pathway aberrations have been identified which drive the different molecular subtypes. Early drugs developed targeting this pathway produced some clinical success but were hampered by pharmacokinetics, tolerability and efficacy problems. This created a need for new PI3K pathway-inhibiting drugs, which would produce more robust results allowing incorporation into treatment regimens for breast cancer patients. In this review, the most promising candidates from the new generation of PI3K-pathway inhibitors is explored, presenting evidence from preclinical and early clinical research, as well as ongoing trials utilising these drugs in breast cancer cohorts. The problems hindering the development of drugs targeting the PI3K pathway are examined, which have created problems for their use as monotherapies. PI3K pathway inhibitor combinations therefore remains a dynamic research area, and their role in combination with immunotherapies and epigenetic therapies is also inspected.

Palmitate and insulin counteract glucose-induced thioredoxin interacting protein (TXNIP) expression in insulin secreting cells via distinct mechanisms

Glucose and palmitate synergistically stimulate insulin secretion, but chronically elevated they induce apoptotic β-cell death. The glucotoxic effect has been attributed, at least partly, to the upregulation of the oxidative stress marker thioredoxin interacting protein (TXNIP). Palmitate downregulates TXNIP expression, the functional significance of which is still under debate. This study examines the mechanism and consequence of palmitate-mediated TXNIP regulation in insulin secreting cells. Palmitate (600 μM) reduced TXNIP mRNA levels in isolated human and mouse islets independently of FFAR1/GPR40. Similar effects of palmitate were observed in INS-1E cells and mimicked by other long chain fatty acids. The lowering of TXNIP mRNA was significant already 1 h after addition of palmitate, persisted for 24 h and was directly translated to changes in TXNIP protein. The pharmacological inhibition of palmitate-induced phosphorylation of AMPK, ERK1/2, JNK and PKCα/β by BML-275, PD98059, SP600125 and Gö6976, respectively, did not abolish palmitate-mediated TXNIP downregulation. The effect of palmitate was superimposed by a time-dependent (8 h and 24 h) decline of TXNIP mRNA and protein. This decline correlated with accumulation of secreted insulin into the medium. Accordingly, exogenously added insulin reduced TXNIP mRNA and protein levels, an effect counteracted by the insulin/IGF-1 receptor antagonist linsitinib. The inhibition of PI3K and Akt/PKB increased TXNIP mRNA levels. The histone deacetylase (HDAC1/2/3) inhibitor MS-275 completely abrogated the time-dependent, insulin-mediated reduction of TXNIP, leaving the effect of palmitate unaltered. Acute stimulation of insulin secretion and chronic accentuation of cell death by palmitate occurred independently of TXNIP regulation. On the contrary, palmitate antagonized glucose-augmented ROS production. In conclusion, glucose-induced TXNIP expression is efficiently antagonized by two independent mechanisms, namely via an autocrine activation of insulin/IGF-1 receptors involving HDAC and by palmitate attenuating oxidative stress of β-cells.

Assessing the Role of Paralog-Specific Sumoylation of HDAC1

Attachment of ubiquitin or ubiquitin-like (Ubl) modifiers, such as the small ubiquitin-related modifier SUMO, is a posttranslational modification (PTM) that reversibly regulates the function and the stability of target proteins. The SUMO paralogs SUMO1 and SUMO2/3, although sharing a common conjugation pathway, seem to play different roles in the cell. Many regulatory mechanisms, which contribute to SUMO-paralog-specific modification, have emerged. We have recently found that cell environment affects SUMO-paralog-specific sumoylation of HDAC1, whose conjugation to SUMO1 and not to SUMO2 facilitates its protein turnover. Here, we describe how to identify SUMO-paralog-specific conjugation of HDAC1 and how the different expression of SUMO E3 ligases in the cell plays an important role in this mechanism.

Metformin synergistically enhances antitumor activity of cisplatin in gallbladder cancer via the PI3K/AKT/ERK pathway

Metformin (Met) is a widely used antidiabetic drug and has demonstrated interesting anticancer effects in various cancer models, alone or in combination with chemotherapeutic drugs. The aim of the present study is to investigate the synergistic effect of Met with cisplatin (Cis) on the tumor growth inhibition of gallbladder cancer cells (GBC-SD and SGC-996) and explore the underlying mechanism. Cells were treated with Met and/or Cis and subjected to cell viability, colony formation, apoptosis, cell cycle, western blotting, xenograft tumorigenicity assay and immunohistochemistry. The results demonstrated that Met and Cis inhibited the proliferation of gallbladder cancer cells, and combination treatment with Met and Cis resulted in a combination index < 1, indicating a synergistic effect. Co-treatment with Met and Cis caused G0/G1 phase arrest by upregulating P21, P27 and downregulating CyclinD1, and induced apoptosis through decreasing the expression of p-PI3K, p-AKT, and p-ERK. In addition, pretreatment with a specific AKT activator (IGF-1) significantly neutralized the pro-apoptotic activity of Met + Cis, suggesting the key role of AKT in this process. More importantly, in nude mice model, Met and Cis in combination displayed more efficient inhibition of tumor weight and volume in the SGC-996 xenograft mouse model than Met or Cis alone. Immunohistochemistry analysis suggests the combinations greatly suppressed tumor proliferation, which is consistent with our in vitro results. In conclusion, our findings indicate that the combination therapy with Met and Cis exerted synergistic antitumor effects in gallbladder cancer cells through PI3K/AKT/ERK pathway, and combination treatment with Met and Cis would be a promising therapeutic strategy for gallbladder cancer patients.

[ARTICLE WITHDRAWN] Dexmedetomidine Inhibits Osteosarcoma Cell Proliferation and Migration, and Promotes Apoptosis by Regulating miR-520a-3p

This study aimed to investigate the effect of dexmedetomidine (DEX) on osteosarcoma (OS) cell line MG63 and to explore the possible relationship between DEX and miR-520-3p in OS. The results showed that DEX could upregulate miR-520-3p, which directly targeted AKT1. Additionally, miR-520-3p also inhibited MG63 cell proliferation and migration, promoted apoptosis, and suppressed protein expressions of AKT, p-AKT, p-mTOR, and p-ERK1/2. DEX can inhibit OS cell proliferation and migration and promote apoptosis by upregulating the expression level of miR-520a-3p. DEX may serve as a potential therapeutic agent in OS treatment, and miR-520a-3p may be a potential target in the therapy of OS.

Dynamic phosphorylation of Histone Deacetylase 1 by Aurora kinases during mitosis regulates zebrafish embryos development

Histone deacetylases (HDACs) catalyze the removal of acetyl molecules from histone and non-histone substrates playing important roles in chromatin remodeling and control of gene expression. Class I HDAC1 is a critical regulator of cell cycle progression, cellular proliferation and differentiation during development; it is also regulated by many post-translational modifications (PTMs). Herein we characterize a new mitosis-specific phosphorylation of HDAC1 driven by Aurora kinases A and B. We show that this phosphorylation affects HDAC1 enzymatic activity and it is critical for the maintenance of a proper proliferative and developmental plan in a complex organism. Notably, we find that Aurora-dependent phosphorylation of HDAC1 regulates histone acetylation by modulating the expression of genes directly involved in the developing zebrafish central nervous system. Our data represent a step towards the comprehension of HDAC1 regulation by its PTM code, with important implications in unravelling its roles both in physiology and pathology.

KLF4 Suppresses Tumor Formation in Genetic and Pharmacological Mouse Models of Colonic Tumorigenesis

The zinc finger transcription factor Krüppel-like factor 4 (KLF4) is frequently downregulated in colorectal cancer. Previous studies showed that KLF4 is a tumor suppressor in the intestinal tract and plays an important role in DNA damage-repair mechanisms. Here, the in vivo effects of Klf4 deletion were examined from the mouse intestinal epithelium (Klf4(ΔIS)) in a genetic or pharmacological setting of colonic tumorigenesis:Apc(Min/⁺) mutation or carcinogen treatment with azoxymethane (AOM), respectively.Klf4 (ΔIS)/Apc (Min/⁺) mice developed significantly more colonic adenomas with 100% penetrance as compared with Apc(Min/⁺) mice with intact Klf4 (Klf4(fl/fl)/Apc (Min/⁺)). The colonic epithelium of Klf4 (ΔIS)/Apc (Min/⁺)mice showed increased mTOR pathway activity, together with dysregulated epigenetic mechanism as indicated by altered expression of HDAC1 and p300. Colonic adenomas from both genotypes stained positive for γH2AX, indicating DNA double-strand breaks. InKlf4 (ΔIS)/Apc (Min/+) mice, this was associated with reduced nonhomologous end joining (NHEJ) repair and homologous recombination repair (HRR) mechanisms as indicated by reduced Ku70 and Rad51 staining, respectively. In a separate model, following treatment with AOM, Klf4 (ΔIS) mice developed significantly more colonic tumors than Klf4 (fl/fl) mice, with more Klf4 (ΔIS) mice harboring K-Rasmutations than Klf4 (fl/fl)mice. Compared with AOM-treated Klf4 (fl/fl)mice, adenomas of treated Klf4 (ΔIS) mice had suppressed NHEJ and HRR mechanisms, as indicated by reduced Ku70 and Rad51 staining. This study highlights the important role of KLF4 in suppressing the development of colonic neoplasia under different tumor-promoting conditions.

IMPLICATIONS

The study demonstrates that KLF4 plays a significant role in the pathogenesis of colorectal neoplasia.

Lupeol Induces Apoptosis and Cell Cycle Arrest of Human Osteosarcoma Cells Through PI3K/AKT/mTOR Pathway

Lupeol, a dietary triterpene present in many fruits and medicinal plants, has been reported to possess many pharmacological properties including anticancer effect in vitro and in vivo However, the activity of lupeol against osteosarcoma remains unclear. The present study is conducted to investigate the anticancer activity and the underlying mechanisms of lupeol on human osteosarcoma cells (MNNG/HOS and MG-63) in vitro and in vivo MNNG/HOS and MG-63 cells were treated by lupeol and subjected to methyl thiazolyl tetrazolium analysis, Hoechst staining, annexin V/propidium iodide double staining, cell cycle analysis, and Western blot analysis. In addition, MNNG/HOS xenograft tumors were established in female nude BALB/c mice, and lupeol was intravenously administered to evaluate the anticancer capacity in vivo Our results showed that lupeol induced apoptosis as well as cell cycle arrest in G0/G1 phase of MNNG/HOS and MG-63 cells in a dose-dependent manner in vitro Furthermore, the protein expression levels of phospho-phosphatidylinositol 3-kinase (p-PI3K), phospho-protein kinase B (p-AKT), p-p70S6K, and cyclin D1 were significantly downregulated, whereas the expression levels of p21 and p27 were upregulated. These protein interactions may play a pivotal role in the regulation of apoptosis and cell cycle arrest. More importantly, our in vivo studies showed that administration of lupeol decreased tumor growth in a dose-dependent manner and has no significant effect on the function of liver and kidney. Taken together, our findings indicated that lupeol can induce apoptosis as well as cell cycle arrest of human osteosarcoma cells through phosphatidylinositol 3-kinase/AKT/mammalian target of rapamycin pathway and might offer a promising new approach in the effective treatment of osteosarcoma.

David and Goliath: chemical perturbation of eukaryotes by bacteria

Environmental microbes produce biologically active small molecules that have been mined extensively as antibiotics and a smaller number of drugs that act on eukaryotic cells. It is known that there are additional bioactives to be discovered from this source. While the discovery of new antibiotics is challenged by the frequent discovery of known compounds, we contend that the eukaryote-active compounds may be less saturated. Indeed, despite there being far fewer eukaryotic-active natural products these molecules interact with a far richer diversity of molecular and cellular targets.

Hormone receptor-independent CXCL10 production is associated with the regulation of cellular factors linked to breast cancer progression and metastasis

Breast cancer (BC) is a major health problem for women around the world. Although advances in the field of molecular therapy have been achieved, the successful therapeutic management of BC, particularly metastatic disease, remains a challenge for patients and clinicians. One of the areas of current investigation is the circulating tumor cells (CTCs), which have a determinant role in the development of distant metastasis. At the present, many of the available treatment strategies for metastatic disease are of limited benefit. However, the elucidation of the mechanisms of tumor progression and metastasis may help to identify key molecules/components that may function as therapeutic targets in the future. In the present study, the functional analysis of CTCs revealed their ability to grow and proliferate to form colonies. Immunofluorescence staining of the CTCs' colonies exhibits elevated expression of cell growth and survival associated proteins such as, survivin, ERK and Akt1. More importantly, the functional screening of the chemokine profile in BC patients' sera revealed an HR-independent elevation of the chemokine CXCL10 when compared to healthy controls. The analysis of chemokines CXCL9 and CXCL11 demonstrated an HR-dependent production pattern. The levels of both CXCL9 and CXCL11 were markedly high in HR+ patients' sera when compared to HR- patients and healthy controls. The functional analysis of HR+ and HR- BC derived cell lines when cultivated in media supplemented with patients' sera demonstrated the alteration of tumor progression and metastasis related proteins. We noted the induction of survivin, β-catenin, MKP-1, pERK, CXCR4 and MMP-1 both at the protein and mRNA levels. The induction of those proteins was in keeping with patients' sera induced cell proliferation as measured by the MTT assay. In conclusion, our data emphasizes the role of chemokines, especially CXCL10, in BC progression and metastasis via the induction of signaling pathways, which mainly involve survivin, β-catenin, MKP-1 and MMP-1.