The Histone Acetyltransferase hMOF is Overexpressed in Non-small Cell Lung Carcinoma

Stabilization of MOF (KAT8) by USP10 promotes esophageal squamous cell carcinoma proliferation and metastasis through epigenetic activation of ANXA2/Wnt signaling

Dysregulation of MOF (also known as MYST1, KAT8), a highly conserved H4K16 acetyltransferase, plays important roles in human cancers. However, its expression and function in esophageal squamous cell carcinoma (ESCC) remain unknown. Here, we report that MOF is highly expressed in ESCC tumors and predicts a worse prognosis. Depletion of MOF in ESCC significantly impedes tumor growth and metastasis both in vitro and in vivo, whereas ectopic expression of MOF but not catalytically inactive mutant (MOF-E350Q) promotes ESCC progression, suggesting that MOF acetyltransferase activity is crucial for its oncogenic activity. Further analysis reveals that USP10, a deubiquitinase highly expressed in ESCC, binds to and deubiquitinates MOF at lysine 410, which protects it from proteosome-dependent protein degradation. MOF stabilization by USP10 promotes H4K16ac enrichment in the ANXA2 promoter to stimulate ANXA2 transcription in a JUN-dependent manner, which subsequently activates Wnt/β-Catenin signaling to facilitate ESCC progression. Our findings highlight a novel USP10/MOF/ANXA2 axis as a promising therapeutic target for ESCC.

The Biological Significance of Targeting Acetylation-Mediated Gene Regulation for Designing New Mechanistic Tools and Potential Therapeutics

The molecular interplay between nucleosomal packaging and the chromatin landscape regulates the transcriptional programming and biological outcomes of downstream genes. An array of epigenetic modifications plays a pivotal role in shaping the chromatin architecture, which controls DNA access to the transcriptional machinery. Acetylation of the amino acid lysine is a widespread epigenetic modification that serves as a marker for gene activation, which intertwines the maintenance of cellular homeostasis and the regulation of signaling during stress. The biochemical horizon of acetylation ranges from orchestrating the stability and cellular localization of proteins that engage in the cell cycle to DNA repair and metabolism. Furthermore, lysine acetyltransferases (KATs) modulate the functions of transcription factors that govern cellular response to microbial infections, genotoxic stress, and inflammation. Due to their central role in many biological processes, mutations in KATs cause developmental and intellectual challenges and metabolic disorders. Despite the availability of tools for detecting acetylation, the mechanistic knowledge of acetylation-mediated cellular processes remains limited. This review aims to integrate molecular and structural bases of KAT functions, which would help design highly selective tools for understanding the biology of KATs toward developing new disease treatments.

Histone Acetyltransferase MOF Orchestrates Outcomes at the Crossroad of Oncogenesis, DNA Damage Response, Proliferation, and Stem Cell Development

The DNA and protein complex known as chromatin is subject to posttranslational modifications (PTMs) that regulate cellular functions such that PTM dysregulation can lead to disease, including cancer. One critical PTM is acetylation/deacetylation, which is being investigated as a means to develop targeted cancer therapies. The histone acetyltransferase (HAT) family of proteins performs histone acetylation. In humans, MOF (hMOF), a member of the MYST family of HATs, acetylates histone H4 at lysine 16 (H4K16ac). MOF-mediated acetylation plays a critical role in the DNA damage response (DDR) and embryonic stem cell development. Functionally, MOF is found in two distinct complexes: NSL (nonspecific lethal) in humans and MSL (male-specific lethal) in flies. The NSL complex is also able to acetylate additional histone H4 sites. Dysregulation of MOF activity occurs in multiple cancers, including ovarian cancer, medulloblastoma, breast cancer, colorectal cancer, and lung cancer. Bioinformatics analysis of KAT8, the gene encoding hMOF, indicated that it is highly overexpressed in kidney tumors as part of a concerted gene coexpression program that can support high levels of chromosome segregation and cell proliferation. The linkage between MOF and tumor proliferation suggests that there are additional functions of MOF that remain to be discovered.

The Functional Analysis of Histone Acetyltransferase MOF in Tumorigenesis

Changes in chromatin structure and heritably regulating the gene expression by epigenetic mechanisms, such as histone post-translational modification, are involved in most cellular biological processes. Thus, abnormal regulation of epigenetics is implicated in the occurrence of various diseases, including cancer. Human MOF (males absent on the first) is a member of the MYST (Moz-Ybf2/Sas3-Sas2-Tip60) family of histone acetyltransferases (HATs). As a catalytic subunit, MOF can form at least two distinct multiprotein complexes (MSL and NSL) in human cells. Both complexes can acetylate histone H4 at lysine 16 (H4K16); however, the NSL complex possesses broader substrate specificity and can also acetylate histone H4 at lysines 5 and 8 (H4K5 and H4K8), suggesting the complexity of the intracellular functions of MOF. Silencing of MOF in cells leads to genomic instability, inactivation of gene transcription, defective DNA damage repair and early embryonic lethality. Unbalanced MOF expression and its corresponding acetylation of H4K16 have been found in certain primary cancer tissues, including breast cancer, medulloblastoma, ovarian cancer, renal cell carcinoma, colorectal carcinoma, gastric cancer, as well as non-small cell lung cancer. In this review, we provide a brief overview of MOF and its corresponding histone acetylation, introduce recent research findings that link MOF functions to tumorigenesis and speculate on the potential role that may be relevant to tumorigenic pathways.

Arsenic Trioxide Reduces Global Histone H4 Acetylation at Lysine 16 through Direct Binding to Histone Acetyltransferase hMOF in Human Cells

Histone post-translational modification heritably regulates gene expression involved in most cellular biological processes. Experimental studies suggest that alteration of histone modifications affects gene expression by changing chromatin structure, causing various cellular responses to environmental influences. Arsenic (As), a naturally occurring element and environmental pollutant, is an established human carcinogen. Recently, increasing evidence suggests that As-mediated epigenetic mechanisms may be involved in its toxicity and carcinogenicity, but how this occurs is still unclear. Here we present evidence that suggests As-induced global histone H4K16 acetylation (H4K16ac) partly due to the direct physical interaction between As and histone acetyltransferase (HAT) hMOF (human male absent on first) protein, leading to the loss of hMOF HAT activity. Our data show that decreased global H4K16ac and increased deacetyltransferase HDAC4 expression occurred in arsenic trioxide (As₂O₃)-exposed HeLa or HEK293T cells. However, depletion of HDAC4 did not affect global H4K16ac, and it could not raise H4K16ac in cells exposed to As₂O₃, suggesting that HDAC4 might not directly be involved in histone H4K16 de-acetylation. Using As-immobilized agarose, we confirmed that As binds directly to hMOF, and that this interaction was competitively inhibited by free As₂O₃. Also, the direct interaction of As and C2CH zinc finger peptide was verified by MAIDI-TOF mass and UV absorption. In an in vitro HAT assay, As₂O₃ directly inhibited hMOF activity. hMOF over-expression not only increased resistance to As and caused less toxicity, but also effectively reversed reduced H4K16ac caused by As exposure. These data suggest a theoretical basis for elucidating the mechanism of As toxicity.

Expression of hMOF, but not HDAC4, is responsible for the global histone H4K16 acetylation in gastric carcinoma

Increasing evidence suggests that the alteration of global histone H4K16 acetylation (H4K16ac) may be involved in several types of cancer. It is known that the global histone H4K16ac level in cells is controlled by several enzymes including histone acetyltransferases (HATs) and histone deacetylases (HDACs). We report in detail which particular enzyme is responsible for global reduction of histone H4K16ac in gastric cancer. Our study included 156 frozen tissue samples of primary diagnosed gastric cancer tissues and matched adjacent or normal tissues, and the gastric cancer cells SGC-7901 and MGC-803. The reverse transcription polymerase chain reaction (RT-PCR), western blot, transient transfection and siRNA knockdown approaches were used. Statistical analysis of the qRT-PCR data revealed that a significant reduction (>2-fold decreased) of hMOF expression in gastric cancer tissues in 81% (42/52) of patients. In patients with gastric cancer, downregulation of hMOF was connected to gastric cancer and tissues with pT2-T4 tumor status, lymph node metastasis and distant metastasis. Overall survival rates revealed a significant difference between the low- and high-hMOF expression groups. However, there was no significant difference by age, gender and cell differentiation. In SGC-7901 and MGC-803 gastric cancer cells, as expected, low expression of hMOF and decreased global histone H4K16ac were observed. Although we did not obtained a statistically significant high-level of HDAC4 in tumor tissues, increased HDAC4 in both gastric cancer cell lines was detected. Therefore, overexpression of hMOF and knockdown of HDAC4 experiments were carried out to investigate the potential coordinating role between hMOF and HDAC4 on global histone H4K16ac in gastric cancer. Overexpression of hMOF increased global H4K16ac in cells, however, no obvious increase of global H4K16ac in HDAC4 knockdown MGC-803 cells was observed. Histone acetyltransferase hMOF and global histone H4K16ac status might be involved in gastric cancer tumorigenic pathways. hMOF, but not HDAC4, is mainly responsible for global histone H4K16ac acetylation in gastric cancer cells.

The histone acetylranseferase hMOF acetylates Nrf2 and regulates anti-drug responses in human non-small cell lung cancer

BACKGROUND AND PURPOSE

The histone acetyltransferase MOF is a member of the MYST family. In mammals, MOF plays critical roles by acetylating histone H4 at K16 and non-histone substrates such as p53. Here we have investigated the role of MOF in human lung cancer and possible new substrates of hMOF.

EXPERIMENTAL APPROACH

Samples of human non-small cell lung cancer (NSCLC) were used to correlate MOF with clinicopathological parameters and NF-E2-related factor 2 (Nrf2) downstream genes. 293T-cells were used to study interactions between MOF and Nrf2, and acetylation of Nrf2 by MOF. Mouse embryonic fibroblast and A549 cells were utilized to assess involvement of MOF in antioxidative and anti-drug responses. A549 cells were used to analysis the role of MOF in anti-drug response in vitro and in vivo.

KEY RESULTS

hMOF was overexpressed in human NSCLC tissues and was associated with large tumour size, advanced disease stage and metastasis, and with poor prognosis. hMOF levels were positively correlated with Nrf2-downstream genes. MOF/hMOF physically interacted with and acetylated Nrf2 at Lys(588) . MOF-mediated acetylation increased nuclear retention of Nrf2 and transcription of its downstream genes. Importantly, MOF/hMOF was essential for anti-oxidative and anti-drug responses in vitro and regulated tumour growth and drug resistance in vivo in an Nrf2-dependent manner.

CONCLUSION AND IMPLICATIONS

hMOF was overexpressed in human NSCLC and was a predictor of poor survival. hMOF-mediated Nrf2 acetylation and nuclear retention are essential for anti-oxidative and anti-drug responses. hMOF may provide a therapeutic target for the treatment of NSCLC.

The histone acetyltransferase hMOF suppresses hepatocellular carcinoma growth

Males absent on the first (MOF) is a histone acetyltransferase belongs to the MYST (MOZ, Ybf2/Sas3, Sas2 and TIP60) family. In mammals, MOF plays critical roles in transcription activation by acetylating histone H4K16, a prevalent mark associated with chromatin decondensation. MOF can also acetylate transcription factor p53 on K120, which is important for activation of pro-apoptotic genes; and TIP5, the largest subunit of NoRC, on K633. However, the role of hMOF in hepatocellular carcinoma remains unknown. Here we find that the expression of hMOF is significantly down-regulated in human hepatocellular carcinoma and cell lines. Furthermore, our survival analysis indicates that low hMOF expression predicts poor overall and disease-free survival. We demonstrate that hMOF knockdown promotes hepatocellular carcinoma growth in vitro and in vivo, while hMOF overexpression reduces hepatocellular carcinoma growth in vitro and in vivo. Mechanically, we show that hMOF regulates the expression of SIRT6 and its downstream genes. In summary, our findings demonstrate that hMOF participates in human hepatocellular carcinoma by targeting SIRT6, and hMOF activators may serve as potential drug candidates for hepatocellular carcinoma therapy.

Coactivator MYST1 regulates nuclear factor-κB and androgen receptor functions during proliferation of prostate cancer cells

In prostate cancer (PCa), the functional synergy between androgen receptor (AR) and nuclear factor-κ B (NF-κB) escalates the resistance to therapeutic regimens and promotes aggressive tumor growth. Although the underlying mechanisms are less clear, gene regulatory abilities of coactivators can bridge the transcription functions of AR and NF-κB. The present study shows that MYST1 (MOZ, YBF2 and SAS2, and TIP60 protein 1) costimulates AR and NF-κB functions in PCa cells. We demonstrate that activation of NF-κB promotes deacetylation of MYST1 by sirtuin 1. Further, the mutually exclusive interactions of MYST1 with sirtuin 1 vs AR regulate the acetylation of lysine 16 on histone H4. Notably, in AR-lacking PC3 cells and in AR-depleted LNCaP cells, diminution of MYST1 activates the cleavage of poly(ADP-ribose) polymerase and caspase 3 that leads to apoptosis. In contrast, in AR-transformed PC3 cells (PC3-AR), depletion of MYST1 induces cyclin-dependent kinase (CDK) N1A/p21, which results in G2M arrest. Concomitantly, the levels of phospho-retinoblastoma, E2F1, CDK4, and CDK6 are reduced. Finally, the expression of tumor protein D52 (TPD52) was unequivocally affected in PC3, PC3-AR, and LNCaP cells. Taken together, the results of this study reveal that the functional interactions of MYST1 with AR and NF-κB are critical for PCa progression.

Regulation and function of histone acetyltransferase MOF

The mammalian MOF (male absent on the first), a member of the MYST (MOZ, YBF2, SAS2, and Tip60) family of histone acetyltransferases (HATs), is the major enzyme that catalyzes the acetylation of histone H4 on lysine 16. Acetylation of K16 is a prevalent mark associated with chromatin decondensation. MOF has recently been shown to play an essential role in maintaining normal cell functions. In this study, we discuss the important roles of MOF in DNA damage repair, apoptosis, and tumorigenesis. We also analyze the role of MOF as a key regulator of the core transcriptional network of embryonic stem cells.

Correlation of low expression of hMOF with clinicopathological features of colorectal carcinoma, gastric cancer and renal cell carcinoma

Human MOF (males absent on the first), as a histone acetyltransferase, is responsible for histone H4K16 acetylation in human cells. Recent studies have shown that the abnormal gene expression of hMOF is involved in certain primary cancers. Here, we first report the involvement of hMOF expression in clinically diagnosed primary colorectal carcinoma (CRC) and gastric cancer. Simultaneously, the correlation of hMOF expression and clinicopathological features in CRC, gastric cancer and renal cell carcinoma (RCC) was analyzed. The hMOF mRNA expression was assessed in 44 CRC, 16 gastric cancer and 47 RCC human tissue samples by quantitative PCR (qPCR). Statistical analysis of qPCR data revealed a significant reduction (>2-fold decrease) of hMOF gene expression in CRC, 57% (25/44), 94% (15/16) in gastric cancer and 74% (35/47) in RCC tissues of the patients. In patients with CRC, lymph node metastasis and tumor stage were associated with hMOF expression patterns. However, no significant association between hMOF expression and tumor types emerged (p>0.05). Interestingly, in patients with gastric cancer, although no statistically significant difference was found between adjacent (<2 cm away from the cancer tissue) and normal tissues (>5 cm away from the cancer tissue), >2-fold reduction of hMOF expression in adjacent tissues had already appeared in 35% of patients. In addition, low expression of hMOF was strongly correlated with tumor differentiation (p<0.05) and survival of patients with gastric cancer (p<0.001). While in patients with RCC, downregulation of hMOF was connected to ccRCC and tissues with T1 tumor status. Our results suggest that downregulation of hMOF may be common in cancer tissues, and may represent a novel biomarker for tumor diagnosis.

A potential diagnostic marker for ovarian cancer: Involvement of the histone acetyltransferase, human males absent on the first

Human males absent on the first (hMOF), a human ortholog of the Drosophila MOF protein, is responsible for histone H4 lysine 16 (H4K16) acetylation in human cells. The depletion of hMOF leads to a global reduction in histone H4K16 acetylation in human cells, genomic instability, cell cycle defects, reduced transcription of certain genes, defective DNA damage repair and early embryonic lethality. Studies have shown that abnormal hMOF gene expression is involved in a number of primary cancers. The present study examined the involvement of hMOF expression and histone H4K16 acetylation in clinically diagnosed primary ovarian cancer tissues. Clinically diagnosed frozen primary ovarian cancer tissues were used for polymerase chain reaction (PCR), quantitative PCR (qPCR), western blotting and immunohistochemical staining approaches. A PCR analysis of mRNA expression in 47 samples revealed a downregulation of hMOF mRNA in 81% of patients, whereas only 13% of patients demonstrated upregulation. qPCR was used to validate the frequent downregulation of hMOF expression in the primary ovarian cancer tissues. As expected, the analysis of hMOF expression in 57 samples revealed that hMOF mRNA expression was significantly downregulated (>2-fold decrease) in 65% of patients, while a <2-fold reduction of hMOF was observed in 10.5% of patients. Furthermore, the expression of hMOF-regulated human leukocyte antigen (HLA) complex 5, (HCP5), was also found to be downregulated in >87% of patients with a decrease in hMOF. hMOF and its regulated gene, HCP5, are frequently downregulated in human ovarian cancer, suggesting that hMOF may be involved in the pathogenesis of the disease.

Epigenetic change in kidney tumor: downregulation of histone acetyltransferase MYST1 in human renal cell carcinoma

Background

MYST1 (also known as hMOF), a member of the MYST family of histone acetyltransferases (HATs) as an epigenetic mark of active genes, is mainly responsible for histone H4K16 acetylation in the cells. Recent studies have shown that the abnormal gene expression of hMOF is involved in certain primary cancers. Here we examined the involvement of hMOF expression and histone H4K16 acetylation in primary renal cell carcinoma (RCC). Simultaneously, we investigated the correlation between the expression of hMOF and clear cell RCC (ccRCC) biomarker carbohydrase IX (CA9) in RCC.

Materials and methods

The frozen RCC tissues and RCC cell lines as materials, the reverse transcription polymerase chain reaction (RT-PCR), western blotting and immunohistochemical staining approaches were used.

Results

RT-PCR results indicate that hMOF gene expression levels frequently downregulated in 90.5% of patients (19/21) with RCC. The reduction of hMOF protein in both RCC tissues and RCC cell lines is tightly correlated with acetylation of histone H4K16. In addition, overexpression of CA9 was detected in 100% of ccRCC patients (21/21). However, transient transfection of hMOF in ccRCC 786–0 cells did not affect both the gene and protein expression of CA9.

Conclusion

hMOF as an acetyltransferase of H4K16 might be involved in the pathogenesis of kidney cancer, and this epigenetic changes might be a new CA9-independent RCC diagnostic maker.