Panobinostat sensitizes AraC-resistant AML cells to the combination of azacitidine and venetoclax.

The majority of acute myeloid leukemia (AML) patients respond to intensive induction therapy, consisting of cytarabine (AraC) and an anthracycline, though more than half experience relapse. Relapsed/refractory (R/R) AML patients are difficult to treat, and their clinical outcomes remain dismal. Venetoclax (VEN) in combination with azacitidine (AZA) has provided a promising treatment option for R/R AML, though the overall survival (OS) could be improved (OS ranges from 4.3 to 9.1 months). Overexpression of c-Myc is associated with chemoresistance in AML. Histone deacetylase (HDAC) inhibitors have been shown to suppress c-Myc and enhance the antileukemic activity of VEN, as well as AZA, though combination of all three has not been fully explored. In this study, we investigated the HDAC inhibitor, panobinostat, in combination with VEN + AZA against AraC-resistant AML cells. Panobinostat treatment downregulated c-Myc and Bcl-xL and upregulated Bim, which enhanced the antileukemic activity of VEN + AZA against AraC-resistant AML cells. In addition, panobinostat alone and in combination with VEN + AZA suppressed oxidative phosphorylation and/or glycolysis in AraC-resistant AML cells. These findings support further development of panobinostat in combination with VEN + AZA for the treatment of AraC-resistant AML.

Feedback Modulation between Human INO80 Chromatin Remodeling Complex and miR-372 in HCT116 Cells.

Human INO80 chromatin remodeling complex (INO80 complex) as a transcription cofactor is widely involved in gene transcription regulation and is frequently highly expressed in tumor cells. However, few reports exist on the mutual regulatory mechanism between INO80 complex and non-coding microRNAs. Herein, we showed evidence that the INO80 complex transcriptionally controls microRNA-372 (miR-372) expression through RNA-Seq analysis and a series of biological experiments. Knocking down multiple subunits in the INO80 complex, including the INO80 catalytic subunit, YY1, Ies2, and Arp8, can significantly increase the expression level of miR-372. Interestingly, mimicking miR-372 expression in HCT116 cells, in turn, post-transcriptionally suppressed INO80 and Arp8 expression at both mRNA and protein levels, indicating the existence of a mutual regulatory mechanism between the INO80 complex and miR-372. The target relationship between miR-372 and INO80 complex was verified using luciferase assays in HCT116 colon cancer cells. As expected, miR-372 mimics significantly suppressed the luciferase activity of pMIR-luc/INO80 and pMIR-luc/Arp8 3'-UTR in cells. In contrast, the miR-372 target sites in the 3'-UTRs linked to the luciferase reporter were mutagenized, and both mutant sites lost their response to miR-372. Furthermore, the mutual modulation between the INO80 complex and miR-372 was involved in cell proliferation and the p53/p21 signaling pathway, suggesting the synergistic anti-tumor role of the INO80 complex and miR372. Our results will provide a solid theoretical basis for exploring miR-372 as a biological marker of tumorigenesis.

The Males Absent on the First (MOF) Mediated Acetylation Alters the Protein Stability and Transcriptional Activity of YY1 in HCT116 Cells.

Yin Yang 1 (YY1) is a well-known transcription factor that controls the expression of many genes and plays an important role in the occurrence and development of various cancers. We previously found that the human males absent on the first (MOF)-containing histone acetyltransferase (HAT) complex may be involved in regulating YY1 transcriptional activity; however, the precise interaction between MOF-HAT and YY1, as well as whether the acetylation activity of MOF impacts the function of YY1, has not been reported. Here, we present evidence that the MOF-containing male-specific lethal (MSL) HAT complex regulates YY1 stability and transcriptional activity in an acetylation-dependent manner. First, the MOF/MSL HAT complex was bound to and acetylated YY1, and this acetylation further promoted the ubiquitin-proteasome degradation pathway of YY1. The MOF-mediated degradation of YY1 was mainly related to the 146-270 amino acid residues of YY1. Further research clarified that acetylation-mediated ubiquitin degradation of YY1 mainly occurred through lysine 183. A mutation at the YY1K183 site was sufficient to alter the expression level of p53-mediated downstream target genes, such as CDKN1A (encoding p21), and it also suppressed the transactivation of YY1 on CDC6. Furthermore, a YY1K183R mutant and MOF remarkably antagonized the clone-forming ability of HCT116 and SW480 cells facilitated by YY1, suggesting that the acetylation-ubiquitin mode of YY1 plays an important role in tumor cell proliferation. These data may provide new strategies for the development of therapeutic drugs for tumors with high expression of YY1.

MiR-372-3p Functions as a Tumor Suppressor in Colon Cancer by Targeting MAP3K2.

MicroRNAs (miRNAs) as small non-coding RNA transcripts bind their complementary sequences in the 3'-untranslated region (3'-UTR) of target messenger RNAs (mRNAs) to regulate their expression. It is known that miR-372 belongs to the miR-371-373 gene cluster and has been found to be abnormally expressed in a variety of cancers, but its precise mechanism in cancer remains to be discovered. In this study, miR-372-3p expression was assessed in 153 frozen tissue samples, including primary diagnosed colon cancer and matched normal and adjacent tissues, using real time quantitative polymerase chain reaction (qPCR). An analysis of qPCR data revealed a significant reduction in miR-372-3p expression (by >2-fold) in colon cancer tissues in 51.5% (34/66) of patients. Consistent with this, mimicking the increased miR-372-3p levels in SW480 colon cancer cells significantly suppressed cell growth and proliferation. Although no direct correlation was found between the low level of miR-372-3p and certain tumor-related factors, such as p53, HRE-2, PMS2, MLH1, MSH2, MSH6, HDAC4, p21, and Wee1, in colon cancer tissues, an inverse relationship between miR-372-3p and Ki67 (a marker of proliferation) or miR-372-3p and MAP3K2(MEKK2), which plays a critical role in the MAPK signaling pathways, was confirmed using tissue samples. The target relationship between miR-372-3p and MAP3K2 was verified using luciferase assays in SW480 colon cancer cells. As expected, miR-372-3p mimics significantly suppressed the luciferase activity of pMIR-luc/MAP3K2 3'-UTR in cells, suggesting that miR-372-3p modulates the expression of MAP3K2 by directly targeting its 3'-UTR. Overall, the results obtained herein suggest that miR-372-3p may function as a tumor-suppressor miRNA in colon cancer by targeting MAP3K2.

Two distinct males absent on the first (MOF)-containing histone acetyltransferases are involved in the epithelial-mesenchymal transition in different ways in human cells.

Human males absent on the first (MOF), a histone acetyltransferase (HAT), forms male-specific lethal (MSL) and non-specific lethal (NSL), two multiprotein HATs, in cells. MSL was originally discovered in dosage compensation study in Drosophila that can specifically acetylate H4K16, while NSL can simultaneously catalyze the H4 at K5, K8, and K16 sites. However, comparative studies of the two HATs in regulating specific biological functions are rarely reported. Here, we present evidence to argue that MSL and NSL function in different ways in the epithelial-to-mesenchymal transition (EMT) process. At first, CRISPR/Cas9-mediated MSL1 (a key subunit of the MSL)-knockout (KO) and NSL3 (a key subunit of the NSL)-KO cells seem to prefer to grow in clusters. Interestingly, the former promotes cell survival and clonal formation, while the latter has the opposite effect on it. Cell staining revealed that MSL1-KO leads to multipolarized spindles, while NSL3-KO causes more lumen-like cells. Furthermore, in Transwell experiments, silencing of MSL1 promotes cell invasion in 293 T, MCF-7, and MDA-MB-231 cells. In contrast, the inhibitory effects on cell invasion are observed in the same NSL3-silenced cells. Consistent with this, mesenchymal biomarkers, like N-cadherin, vimentin, and snail, are negatively correlated with the expression level of MSL1; however, a positive relationship between these proteins and NSL3 in cells has been found. Further studies have clarified that MSL1, but not NSL3, can specifically bind to the E-box-containing Snail promoter region and thereby negatively regulate Snail transactivation. Also, silencing of MSL1 promotes the lung metastasis of B16F10 melanoma cells in mice. Finally, ChIP-Seq analysis indicated that the NSL may be mainly involved in phosphoinositide-mediated signaling pathways. Taken together, the MOF-containing MSL and NSL HATs may regulate the EMT process in different ways in order to respond to different stimuli.

PSMA-Targeted Supramolecular Nanoparticles Prepared From Cucurbit[8]uril-Based Ternary Host-Guest Recognition for Prostate Cancer Therapy.

Nanomedicines play an important role in cancer therapy; however, some drawbacks including unsatisfactory efficacy and side effects arising from indiscriminate drug release retard their clinical applications. Although functionalization of nanomedicines through covalent interactions can improve the pharmacokinetics and efficacy of the loaded drugs, complicated and tedious synthesis greatly limits the exploration of multifunctional nanoparticles. Herein, we utilize a supramolecular strategy to design a nanomedicine for targeted drug delivery through cucurbit[8]uril-based host-guest ternary complexation and successfully prepare prostate-specific membrane antigen (PSMA)-targeted supramolecular nanoparticles encapsulating doxorubicin (DOX). In vitro studies exhibit targeted modification via noncovalent enhance anticancer efficiency of DOX due to the increased cell uptake on account of receptor-mediated endocytosis. This design provides a new strategy for the development of sophisticated drug delivery systems and holds perspective potentials in precise cancer treatments.

Potential Biomarkers of miR-371-373 Gene Cluster in Tumorigenesis.

microRNAs (miRNAs) are small non-coding RNA transcripts (20-24 nucleotides) that bind to their complementary sequences in the 3'-untranslated regions (3'-UTR) of targeted genes to negatively or positively regulate their expression. miRNAs affect the expression of genes in cells, thereby contributing to several important biological processes, including tumorigenesis. Identifying the miRNA cluster as a human embryonic stem cell (hESC)-specific miRNAs initially led to the identification of miR-371, miR-372, miR-373, and miR-373*, which can ultimately be translated into mature miRNAs. Recent evidence suggests that miR-371-373 genes are abnormally expressed in various cancers and act either as oncogenes or tumor suppressors, indicating they may be suitable as molecular biomarkers for cancer diagnosis and prevention. In this article, we summarize recent studies linking miR-371-373 functions to tumorigenesis and speculate on the potential applications of miR-371-373 as biomarkers for cancer diagnosis and treatment.

KAT8/MOF-Mediated Anti-Cancer Mechanism of Gemcitabine in Human Bladder Cancer Cells.

Histone acetylation is a well-characterized epigenetic modification controlled by histone acetyltransferases (HATs) and histone deacetylases (HDACs). Imbalanced histone acetylation has been observed in many primary cancers. Therefore, efforts have been made to find drugs or small molecules such as HDAC inhibitors that can revert acetylation levels to normal in cancer cells. We observed dose-dependent reduction in the endogenous and exogenous protein expression levels of KAT8 (also known as human MOF), a member of the MYST family of HATs, and its corresponding histone acetylation at H4K5, H4K8, and H4K16 in chemotherapy drug gemcitabine (GEM)-exposed T24 bladder cancer (BLCA) cells. Interestingly, the reduction in MOF and histone H4 acetylation was inversely proportional to GEM-induced γH2AX, an indicator of chemotherapy drug effectiveness. Furthermore, pGL4-MOF-Luc reporter activities were significantly inhibited by GEM, thereby suggesting that GEM utilizes an MOF-mediated anti-BLCA mechanism of action. In the CCK-8, wound healing assays and Transwell® experiments, the additive effects on cell proliferation and migration were observed in the presence of exogenous MOF and GEM. In addition, the promoted cell sensitivity to GEM by exogenous MOF in BLCA cells was confirmed using an Annexin V-FITC/PI assay. Taken together, our results provide the theoretical basis for elucidating the anti-BLCA mechanism of GEM.

Functional Analysis of O-GlcNAcylation in Cancer Metastasis.

One common and reversible type of post-translational modification (PTM) is the addition of O-linked ß-N-acetylglucosamine (O-GlcNAc) modification (O-GlcNAcylation), and its dynamic balance is controlled by O-GlcNAc transferase (OGT) and glycoside hydrolase O-GlcNAcase (OGA) through the addition or removal of O-GlcNAc groups. A large amount of research data confirms that proteins regulated by O-GlcNAcylation play a pivotal role in cells. In particularly, imbalanced levels of OGT and O-GlcNAcylation have been found in various types of cancers. Recently, increasing evidence shows that imbalanced O-GlcNAcylation directly or indirectly impacts the process of cancer metastasis. This review summarizes the current understanding of the influence of O-GlcNAc-proteins on the regulation of cancer metastasis. It will provide a theoretical basis to further elucidate of the molecular mechanisms underlying cancer emergence and progression.

Small Molecules Targeting the Specific Domains of Histone-Mark Readers in Cancer Therapy.

Epigenetic modifications (or epigenetic tags) on DNA and histones not only alter the chromatin structure, but also provide a recognition platform for subsequent protein recruitment and enable them to acquire executive instructions to carry out specific intracellular biological processes. In cells, different epigenetic-tags on DNA and histones are often recognized by the specific domains in proteins (readers), such as bromodomain (BRD), chromodomain (CHD), plant homeodomain (PHD), Tudor domain, Pro-Trp-Trp-Pro (PWWP) domain and malignant brain tumor (MBT) domain. Recent accumulating data reveal that abnormal intracellular histone modifications (histone marks) caused by tumors can be modulated by small molecule-mediated changes in the activity of the above domains, suggesting that small molecules targeting histone-mark reader domains may be the trend of new anticancer drug development. Here, we summarize the protein domains involved in histone-mark recognition, and introduce recent research findings about small molecules targeting histone-mark readers in cancer therapy.

Quercetin pretreatment enhances the radiosensitivity of colon cancer cells by targeting Notch-1 pathway.

Cancer stem-like cells are rare immortal cells within tumor, which are thought to play important roles in ionizing radiation (IR) therapy-resistance. Quercetin is a natural flavonoid with potential anti-cancer properties without significant cytotoxicity in normal tissues. In this study, we demonstrated that quercetin-IR combination treatment exhibited more dramatic anti-cancer effect than either quercetin or IR treatment alone via targeting colon cancer stem cells (CSCs) and inhibiting the Notch-1 signaling. These effects were further verified by in vivo studies which showed remarkable decrease of the CSCs markers and the expression of Notch-1 signaling proteins in human colon cancer xenografts in nude mice. Co-treatment with quercetin and low dose of radiation significantly reduced the expressions of all five proteins of γ-secretase complex in HT-29 and DLD-1 cells. In addition, ectopic expression of the Notch intracellular domain (NICD) partly reversed the inhibition effects by the combination therapy. In conclusion, our results indicated that the combination of quercetin (20 µM) and IR (5Gy) might be a promising therapeutic strategy for colon cancer treatment by targeting colon cancer stem-like cells and inhibiting the Notch-1 signaling. In future studies, we intend to further explore the potential therapeutic efficacy of the quercetin-radiation combination treatment in clinical trials.

O-GlcNAc-Modification of NSL3 at Thr755 Site Maintains the Holoenzyme Activity of MOF/NSL Histone Acetyltransfease Complex.

Both OGT1 (O-linked ß-N-acetylglucosamine (O-GlcNAc) transferase isoform 1) and NSL3 (nonspecific lethal protein 3) are crucial components of the MOF (males absent on the first)/NSL histone acetyltransferase complex. We previously described how global histone H4 acetylation levels were modulated by OGT1/O-GlcNAcylation-mediated NSL3 stability. However, the specific modification site of NSL3 and its molecular mechanism of protein stability remain unknown. Here, we present evidence from biochemical experiments arguing that O-GlcNAcylation of NSL3 at Thr755 is tightly associated with holoenzyme activity of the MOF/NSL complex. Using in vitro O-GlcNAc-transferase assays combined with mass spectrometry, we suppose that the residue Thr755 on NSL3 C-terminus is the major site O-GlcNAc-modified by OGT1. Importantly, O-GlcNAcylation of this site is involved in the regulation of the ubiquitin-degradation of NSL3, because this site mutation (T755A) promotes the ubiquitin-mediated degradation of NSL3. Further in-depth research found that ubiquitin conjugating enzyme E2 S (UBE2S) accelerated the degradation of NSL3 via direct binding to it. Interestingly, OGT1 and UBE2S competitively bind to NSL3, suggesting the coordination of OGT1-UBE2S in regulating NSL3 stability. Furthermore, O-GlcNAcylation of NSL3 Thr755 site regulates the histone H4 acetylation levels at lysine 5, 8, and 16, suggesting that the O-GlcNAcylation of NSL3 at Thr755 is required for maintaining the integrity and holoenzyme activity of the MOF/NSL complex. In colony formation assays, we found that the integrity of the complex impacts the proliferation of the lung carcinoma type II epithelium-like A549 cells. Taken together, our results provide new insight into the elucidation of the molecular mechanism of the MOF/NSL complex.

YY1/BCCIP Coordinately Regulates P53-Responsive Element (p53RE)-Mediated Transactivation of p21Waf1/Cip1.

Transactivation of p21 (cyclin-dependent kinase inhibitor 1A, CDKN1A) is closely related to the recruitment of transcription cofactors at the p53 responsive elements (p53REs) in its promoter region. Human chromatin remodeling enzyme INO80 can be recruited to the p53REs of p21 promoter and negatively regulates p21. As one of the key subunits of the INO80 complex, YY1 has also been confirmed to bind to the p53RE sites of p21 promoter. Importantly, YY1 was recently reported to be bound and stabilized by BCCIP (BRCA2 and CDKN1A-interacting protein). Therefore, we hypothesized that the YY1/BCCIP complex plays an important role in regulating the transactivation of p21. Here we present evidence that the YY1/BCCIP complex coordinatively regulates p53RE-mediated p21 transactivation. We first confirmed the cross-interaction between YY1, BCCIP, and p53, suggesting an intrinsic link between three proteins in the regulation of p21 transcription. In dual luciferase assays, YY1 inhibited p53RE-mediated luciferase activity, whereas BCCIP revealed the opposite effect. More interestingly, the region 146-270 amino acids of YY1, which bound to BCCIP, increased p53-mediated luciferase activity, indicating the complexity of the YY1/BCCIP complex in co-regulating p21 transcription. Further in-depth research confirmed the co-occupancy of YY1/BCCIP with p53 at the p53RE-proximal region of p21. Lentiviral-mediated knockdown of BCCIP inhibited the recruitment of p53 and YY1 at the p53RE proximal region of p21; however, this phenomenon was reversed by expressing exogenous YY1, suggesting the collaborative regulation of YY1/BCCIP complex in p53RE-mediated p21 transcription. These data provide new insights into the transcriptional regulation of p21 by the YY1/BCCIP complex.

Expression, purification, and in vitro mitochondrial interaction analysis of full-length and truncated human tumor suppresser p53.

p53 is a potent tumor suppressor which can prevent the propagation of cells carrying oncogenic lesions via a multitude of pathways. Besides the transactivation of downstream genes encoding proapoptotic proteins, p53 is also able to physically interact with mitochondria and induce apoptosis through a so called transcriptional-independent pathway. In this study, we described a quick method for the expression and purification of soluble recombinant p53 and its different truncations in E. coli. These proteins are able to interact with mitochondria and induce mitochondrial outer membrane permeabilization and associated downstream apoptotic events in a cell-free apoptosis analysis system.

Prefrontal projections to the thalamic nucleus reuniens mediate fear extinction.

The thalamic nucleus reuniens (RE) receives dense projections from the medial prefrontal cortex (mPFC), interconnects the mPFC and hippocampus, and may serve a pivotal role in regulating emotional learning and memory. Here we show that the RE and its mPFC afferents are critical for the extinction of Pavlovian fear memories in rats. Pharmacological inactivation of the RE during extinction learning or retrieval increases freezing to an extinguished conditioned stimulus (CS); renewal of fear outside the extinction context was unaffected. Suppression of fear in the extinction context is associated with an increase in c-fos expression and spike firing in RE neurons to the extinguished CS. The role for the RE in suppressing extinguished fear requires the mPFC, insofar as pharmacogenetically silencing mPFC to RE projections impairs the expression of extinction memory. These results reveal that mPFC-RE circuits inhibit the expression of fear, a function that is essential for adaptive emotional regulation.

'O-GlcNAc Code' Mediated Biological Functions of Downstream Proteins.

As one of the post-translational modifications, O-linked ß-N-acetylglucosamine (O-GlcNAc) modification (O-GlcNAcylation) often occurs on serine (Ser) and threonine (Thr) residues of specific substrate cellular proteins via the addition of O-GlcNAc group by O-GlcNAc transferase (OGT). Maintenance of normal intracellular levels of O-GlcNAcylation is controlled by OGT and glycoside hydrolase O-GlcNAcase (OGA). Unbalanced O-GlcNAcylation levels have been involved in many diseases, including diabetes, cancer, and neurodegenerative disease. Recent research data reveal that O-GlcNAcylation at histones or non-histone proteins may provide recognition platforms for subsequent protein recruitment and further initiate intracellular biological processes. Here, we review the current understanding of the 'O-GlcNAc code' mediated intracellular biological functions of downstream proteins.

The chromatin remodeling protein INO80 contributes to the removal of H2A.Z at the p53-binding site of the p21 gene in response to doxorubicin.

Transcriptional activation of p21 (cyclin-dependent kinase inhibitor 1A) due to DNA damage often alters the distribution of histone variant H2A.Z at the p21 gene. However, whether the human INO80 complex regulates changes in H2A.Z at the p21 promoter is unclear. We show here that activation of p21 expression by doxorubicin (Doxo) in U2OS cells is required for removal of H2A.Z by INO80 at the p53-binding site proximal region (-2.2 kb) of the p21 promoter. A purified INO80 complex, but not the INO80E653Q mutant-complex, which lost DNA-sliding activity, is mainly responsible for removing H2A.Z from reconstituted nucleosomes in vitro. This activity was enhanced with MOF-mediated histone acetylation, suggesting that INO80 more readily removes H2A.Z from loosened nucleosomes. Also, co-occupancy of INO80 and H2A.Z -2.2 kb upstream of the p21 transcriptional start site (TSS) was observed. H2A.Z at this region was removed in a short time after Doxo treatment and activated p21 expression. However, p21 induction was inhibited by INO80 knockdown by delaying H2A.Z removal, indicating the need for INO80. Moreover, shMOF-mediated histone acetylation reduced recruitment of INO80 -2.2 kb upstream of p21 TSS and inhibited the removal of H2A.Z in Doxo-treated cells. These data provide new insights into the transcriptional regulation of p21 by the INO80 complex.

BCCIP binds to and activates its promoter in a YY1-dependent fashion in HCT116 cells.

The restriction of Yin Yang 1 (YY1) at BRCA2 and CDKN1A/p21-interacting protein (BCCIP) transcriptional start site (TSS) proximal region in several human cancer cell lines was found by analyzation of ChIP-Seq database from UCSC Genome Browser (http://genome.ucsc.edu). However, whether the stabilization of YY1 by BCCIP impacts its recruitment in the BCCIP promoter region is unclear. Here, we present evidence that transcriptional regulation of YY1 on BCCIP is closely related to YY1 stability in HCT116 human colon cancer cells. YY1 stabilization was in turn regulated by BCCIP, suggesting the existence of a BCCIP-YY1 feedback loop in regulating BCCIP transcription by the YY1. Overexpression of BCCIP stabilized YY1 while knockdown of BCCIP reduced YY1 protein level. In addition, direct interaction between YY1 and BCCIP was confirmed by coimmunoprecipitation approach. Also, the N-terminus region of BCCIP, including the internal conserved domain (ICD), was responsible for binding with the amino acid 146-270 of YY1. More importantly, YY1 stability was related to the BCCIP/ICD domain-mediated YY1 ubiquitination pathway. Moreover, a limited BCCIP promoter region containing YY1 binding site (CCGCCATC) was tightly associated with the pGL4-BCCIP-Luc luciferase activity. In ChIP assays, shBCCIP lentiviral-mediated YY1 instability decreased recruitment of the YY1 at BCCIP TSS proximal region, which could not be restored by YY1 overexpression. Furthermore, knockdown of YY1 inhibited the binding of BCCIP itself at BCCIP promoter region proximal to TSS, demonstrating that transcriptional regulation of the YY1 on BCCIP can be modulated by BCCIP itself in a YY1-dependent fashion.

Potential coordination role between O-GlcNAcylation and epigenetics.

Dynamic changes of the post-translational O-GlcNAc modification (O-GlcNAcylation) are controlled by O-linked ß-N-acetylglucosamine (O-GlcNAc) transferase (OGT) and the glycoside hydrolase O-GlcNAcase (OGA) in cells. O-GlcNAcylation often occurs on serine (Ser) and threonine (Thr) residues of the specific substrate proteins via the addition of O-GlcNAc group by OGT. It has been known that O-GlcNAcylation is not only involved in many fundamental cellular processes, but also plays an important role in cancer development through various mechanisms. Recently, accumulating data reveal that O-GlcNAcylation at histones or non-histone proteins can lead to the start of the subsequent biological processes, suggesting that O-GlcNAcylation as 'protein code' or 'histone code' may provide recognition platforms or executive instructions for subsequent recruitment of proteins to carry out the specific functions. In this review, we summarize the interaction of O-GlcNAcylation and epigenetic changes, introduce recent research findings that link crosstalk between O-GlcNAcylation and epigenetic changes, and speculate on the potential coordination role of O-GlcNAcylation with epigenetic changes in intracellular biological processes.

Lentiviral-mediated overexpression of KCTD12 inhibits the proliferation of human uveal melanoma OCM-1 cells.

Human potassium channel tetramerization domain containing 12 (KCTD12, also known as Pfetin) is a member of the KCTD family which consists of 26 members. It has been reported that KCTD12 regulates agonist potency and kinetics of GABAB receptor signaling. Proteomic analysis indicates that KCTD12 may be a potential biomarker for the diagnosis and prognosis of gastrointestinal stromal tumors. However, little has been reported concerning the role of KCTD12 in the other tumor types. In the present study, we designed and subcloned N-terminally Flag-tagged human KCTD12 into the pLVX­Puro vector. We then generated a human uveal melanoma cell line (OCM-1) stably expressing KCTD12. Using this stable cell line, we performed a series of experiments including colony formation, invasion, migration and wound-healing assays, flow cytometry and western blotting. Based on the experimental results, we first demonstrated that KCTD12 effectively suppressed the proliferation of OCM-1 cells and limited the spread of OCM-1 cells. In the flow cytometric analysis, prolongation of the progression of G2/M to G1 phase in the KCTD12-overexpressing OCM-1 cells was observed. In addition, inhibition of KCTD12-overexpressing OCM-1 cell xenograft growth in nude mice was observed. Taken together, KCTD12 may serve as a novel therapeutic target for patients with uveal melanoma.