N-α-acetyltransferase 10 protein suppresses cancer cell metastasis by binding PIX proteins and inhibiting Cdc42/Rac1 activity

miR-137: a potential therapeutic target for lung cancer

Lung cancer is a prevalent malignancy and the leading cause of cancer-related deaths, posing a significant threat to human health. Despite advancements in treatment, the prognosis for lung cancer patients remains poor due to late diagnosis, cancer recurrence, and drug resistance. Epigenetic research, particularly in microRNAs, has introduced a new avenue for cancer prevention and treatment. MicroRNAs, including miR-137, play a vital role in tumor development by regulating various cellular processes. MiR-137 has garnered attention for its tumor-suppressive properties, with studies showing its potential in inhibiting cancer progression. In lung cancer, miR-137 is of particular interest, with numerous reports exploring its role and mechanisms. A comprehensive review is necessary to consolidate current evidence. This review highlights recent studies on miR-137 in lung cancer, covering cell proliferation, migration, apoptosis, drug resistance, and therapy, emphasizing its potential as a biomarker and therapeutic target for lung cancer treatment and prognosis.

The Discovery of GIT1/β-Pix Inhibitors: Virtual Screening and Biological Evaluation of New Small-molecule Compounds with Anti-invasion Effect in Gastrointestinal Neoplasms

Background and Objective

GIT1 (G-protein-coupled receptor kinase interacting protein-1) has been found to be highly related with cancer cell invasion and metastasis in many cancer types. β-Pix (p21-activated kinase-interacting exchange factor) is one of the proteins that interact with GIT1. Targeting GIT1/β-Pix complex might be a potential therapeutic strategy for interfering cancer metastasis. However, at present, no well-recognized small-molecule inhibitor targeting GIT1/β-Pix is available. Thus, we aim to discover novel GIT1/β-Pix inhibitors with simple scaffold, high activity and low toxicity to develop new therapeutic strategies to restrain cancer metastasis.

Methods

GIT1/β-Pix inhibitors were identified from ChemBridge by virtual screening. Briefly, the modeling of GIT1 was performed and the establishment of GIT1/β-Pix binding pocket enabled the virtual screening to identify the inhibitor. In addition, direct binding of the candidate molecules to GIT1 was detected by biolayer interferometry (BLI) to discover the hit compound. Furthermore, the inhibitory effect on invasion of stomach and colon cancer cells in vitro was carried out by the transwell assay and detection of epithelial-mesenchymal transition (EMT)-related proteins. Finally, the binding mode of hit compound to GIT1 was estimated by molecular dynamics simulation to analyze the key amino residues to guide further optimization.

Results

We selected the top 50 compounds from the ChemBridge library by virtual screening. Then, by skeleton similarity analysis nine compounds were selected for further study. Furthermore, the direct interaction of nine compounds to GIT1 was detected by BLI to obtain the best affinitive compound. Finally, 17302836 was successfully identified (KD = 84.1±2.0 μM). In vitro tests on 17302836 showed significant anti-invasion effect on gastric cancer and colorectal cancer.

Conclusion

We discovered a new GIT1/β-Pix inhibitor (17302836) against gastrointestinal cancer invasion and metastasis. This study provides a promising candidate for developing new GIT1/β-Pix inhibitors for tumor treatment.

The role of Nα-terminal acetylation in protein conformation

Especially in higher eukaryotes, the N termini of proteins are subject to enzymatic modifications, with the acetylation of the alpha-amino group of nascent polypeptides being a prominent one. In recent years, the specificities and substrates of the enzymes responsible for this modification, the Nα-terminal acetyltransferases, have been mapped in several proteomic studies. Aberrant expression of, and mutations in these enzymes were found to be associated with several human diseases, explaining the growing interest in protein Nα-terminal acetylation. With some enzymes, such as the Nα-terminal acetyltransferase A complex having thousands of possible substrates, researchers are now trying to decipher the functional outcome of Nα-terminal protein acetylation. In this review, we zoom in on one possible functional consequence of Nα-terminal protein acetylation; its effect on protein folding. Using selected examples of proteins associated with human diseases such as alpha-synuclein and huntingtin, here, we discuss the sometimes contradictory findings of the effects of Nα-terminal protein acetylation on protein (mis)folding and aggregation.

NAA10 gene expression is associated with mesenchymal transition, dedifferentiation, and progression of clear cell renal cell carcinoma

INTRODUCTION

We aimed to investigate the expression and prognostic role of NAA10 in clear cell renal cell carcinoma (ccRCC).

MATERIAL AND METHODS

We performed a gene expression and survival analysis based on the human cancer genome atlas database of ccRCC patients (TCGA-KIRC).

RESULTS

The patients in the TCGA-KIRC (n = 537) were divided into two subgroups: NAA10-low and NAA10-high expression groups. NAA10-high ccRCC exhibited higher T stages (p = 0.002), a higher frequency of distant metastasis (p = 0.018), more advanced AJCC stages (p < 0.001), a lower overall survival time (p = 0.036), and a lower survival rate (p < 0.001). NAA10-high ccRCC was associated with increased activity of non-specific oncogenic pathways, including oxidative phosphorylation (p < 0.001) and cell cycle progression [G2 to M phase transition (p = 0.045) and E2F targets (p < 0.001)]. Additionally, the NAA10-high tumors showed reduced apoptosis via TRIAL pathways (p < 0.001) and increased levels of activity that promoted epithelial-mesenchymal transition (p = 0.026) or undifferentiation (p = 0.01). In ccRCC, NAA10 expression was found to be a negative prognostic factor in both non-metastatic (p < 0.001) and metastatic tumors (p = 0.032).

CONCLUSIONS

In ccRCC, NAA10 expression was shown to be a negative prognostic factor related to tumor progression rather than tumor initiation, and high NAA10 expression promoted epithelial-mesenchymal transition and undifferentiation.

The role of N-acetyltransferases in cancers

Cancer is a major global health problem that disrupts the balance of normal cellular growth and behavior. Mounting evidence has shown that epigenetic modification, specifically N-terminal acetylation, play a crucial role in the regulation of cell growth and function. Acetylation is a co- or post-translational modification to regulate important cellular progresses such as cell proliferation, cell cycle progress, and energy metabolism. Recently, N-acetyltransferases (NATs), enzymes responsible for acetylation, regulate signal transduction pathway in various cancers including hepatocellular carcinoma, breast cancer, lung cancer, colorectal cancer and prostate cancer. In this review, we clarify the regulatory role of NATs in cancer progression, such as cell proliferation, metastasis, cell apoptosis, autophagy, cell cycle arrest and energy metabolism. Furthermore, the mechanism of NATs on cancer remains to be further studied, and few drugs have been developed. This provides us with a new idea that targeting acetylation, especially NAT-mediated acetylation, may be an attractive way for inhibiting cancer progression.

The mechanistic role of NAT10 in cancer: Unraveling the enigmatic web of oncogenic signaling

N-acetyltransferase 10 (NAT10), a versatile enzyme, has gained considerable attention as a significant player in the complex realm of cancer biology. Its enigmatic role in tumorigenesis extends across a wide array of cellular processes, impacting cell growth, differentiation, survival, and genomic stability. Within the intricate network of oncogenic signaling, NAT10 emerges as a crucial agent in multiple cancer types, such as breast, lung, colorectal, and leukemia. This compelling research addresses the intricate complexity of the mechanistic role of NAT10 in cancer development. By elucidating its active participation in essential physiological processes, we investigate the regulatory role of NAT10 in cell cycle checkpoints, coordination of chromatin remodeling, and detailed modulation of the delicate balance between apoptosis and cell survival. Perturbations in NAT10 expression and function have been linked to oncogenesis, metastasis, and drug resistance in a variety of cancer types. Furthermore, the bewildering interactions between NAT10 and key oncogenic factors, such as p53 and c-Myc, are deciphered, providing profound insights into the molecular underpinnings of cancer pathogenesis. Equally intriguing, the paradoxical role of NAT10 as a potential tumor suppressor or oncogene is influenced by context-dependent factors and the cellular microenvironment. This study explores the fascinating interplay of genetic changes, epigenetic changes, and post-translational modifications that shape the dual character of NAT10, revealing the delicate balance between cancer initiation and suppression. Taken together, this overview delves deeply into the enigmatic role of NAT10 in cancer, elucidating its multifaceted roles and its complex interplay with oncogenic networks.

Multiple impacts of Naa10p on cancer progression: Molecular functions and clinical prospects

Nα-acetyltransferase 10 protein (Naa10p) is known as the catalytic subunit of N-terminal acetyltransferases A (NatA) complex, associating with Naa15p to acetylate N-termini of the human proteome. Recent investigations have unveiled additional functions for Naa10p, encompassing lysine ε-acetylation and acetyltransferase-independent activities. Its pleiotropic roles have been implicated in diverse physiological and pathological contexts. Emerging evidence has implicated Naa10p in cancer progression, demonstrating dual attributes as an oncogene or a tumor suppressor contingent on the cancer type and acetyltransferase activity context. In this comprehensive review, we present a pan-cancer analysis aimed at elucidating the intricacies underlying Naa10p dysregulation in cancer. Our findings propose the potential involvement of c-Myc as a modulatory factor influencing Naa10p expression. Moreover, we provide a consolidated summary of recent advancements in understanding the intricate molecular underpinnings through which Naa10p contributes to cancer cell proliferation and metastasis. Furthermore, we delve into the multifaceted nature of Naa10p's roles in regulating cancer behaviors, potentially attributed to its interactions with a repertoire of partner proteins. Through an exhaustive exploration of Naa10p's functions, spanning its acetylation activity and acetyltransferase-independent functionalities, this review offers novel insights with implications for targeted therapeutic strategies involving this pivotal protein in the realm of cancer therapeutics.

Guanine nucleotide exchange factors for Rho GTPases (RhoGEFs) as oncogenic effectors and strategic therapeutic targets in metastatic cancer

Metastatic cancer cells dynamically adjust their shape to adhere, invade, migrate, and expand to generate secondary tumors. Inherent to these processes is the constant assembly and disassembly of cytoskeletal supramolecular structures. The subcellular places where cytoskeletal polymers are built and reorganized are defined by the activation of Rho GTPases. These molecular switches directly respond to signaling cascades integrated by Rho guanine nucleotide exchange factors (RhoGEFs), which are sophisticated multidomain proteins that control morphological behavior of cancer and stromal cells in response to cell-cell interactions, tumor-secreted factors and actions of oncogenic proteins within the tumor microenvironment. Stromal cells, including fibroblasts, immune and endothelial cells, and even projections of neuronal cells, adjust their shapes and move into growing tumoral masses, building tumor-induced structures that eventually serve as metastatic routes. Here we review the role of RhoGEFs in metastatic cancer. They are highly diverse proteins with common catalytic modules that select among a variety of homologous Rho GTPases enabling them to load GTP, acquiring an active conformation that stimulates effectors controlling actin cytoskeleton remodeling. Therefore, due to their strategic position in oncogenic signaling cascades, and their structural diversity flanking common catalytic modules, RhoGEFs possess unique characteristics that make them conceptual targets of antimetastatic precision therapies. Preclinical proof of concept, demonstrating the antimetastatic effect of inhibiting either expression or activity of βPix (ARHGEF7), P-Rex1, Vav1, ARHGEF17, and Dock1, among others, is emerging.

Crosstalk between epigenetics and tumor promoting androgen signaling in prostate cancer

Prostate cancer (PCa) is one of the major health burdens among all cancer types in men globally. Early diagnosis and efficacious treatment options are highly warranted as far as the incidence of PCa is concerned. Androgen-dependent transcriptional activation of androgen receptor (AR) is central to the prostate tumorigenesis and therefore hormonal ablation therapy remains the first line of treatment for PCa in the clinics. However, the molecular signaling engaged in AR-dependent PCa initiation and progression is infrequent and diverse. Moreover, apart from the genomic changes, non-genomic changes such as epigenetic modifications have also been suggested as critical regulator of PCa development. Among the non-genomic mechanisms, various epigenetic changes such as histones modifications, chromatin methylation and noncoding RNAs regulations etc. play decisive role in the prostate tumorigenesis. Given that epigenetic modifications are reversible using pharmacological modifiers, various promising therapeutic approaches have been designed for the better management of PCa. In this chapter, we discuss the epigenetic control of tumor promoting AR signaling that underlies the mechanism of prostate tumorigenesis and progression. In addition, we have discussed the approaches and opportunities to develop novel epigenetic modifications based therapeutic strategies for targeting PCa including castrate resistant prostate cancer (CRPC).

EF-24, a Curcumin Analog, Inhibits Cancer Cell Invasion in Human Nasopharyngeal Carcinoma through Transcriptional Suppression of Matrix Metalloproteinase-9 Gene Expression

Cancer metastasis is a main cause of failure in treating subjects with nasopharyngeal carcinoma (NPC) and is frequently linked to high death rates. EF-24, an analog of curcumin, has exhibited many anti-cancer properties and enhanced bioavailability over curcumin. Nevertheless, the effects of EF-24 on the invasiveness of NPC are poorly understood. In this study, we demonstrated that EF-24 effectively inhibited TPA-induced motility and invasion responses of human NPC cells but elicited very limited cytotoxicity. In addition, the TPA-induced activity and expression of matrix metalloproteinase-9 (MMP-9), a crucial mediator of cancer dissemination, were found to be reduced in EF-24-treated cells. Our reporter assays revealed that such a reduction in MMP-9 expression by EF-24 was transcriptionally mediated by NF-κB via impeding its nuclear translocation. Further chromatin immunoprecipitation assays displayed that the EF-24 treatment decreased the TPA-induced interaction of NF-κB with the MMP-9 promoter in NPC cells. Moreover, EF-24 inhibited the activation of JNK in TPA-treated NPC cells, and the treatment of EF-24 together with a JNK inhibitor showed a synergistic effect on suppressing TPA-induced invasion responses and MMP-9 activities in NPC cells. Taken together, our data demonstrated that EF-24 restrained the invasiveness of NPC cells through the transcriptional suppression of MMP-9 gene expression, implicating the usefulness of curcumin or its analogs in controlling the spread of NPC.

EF-24 inhibits TPA-induced cellular migration and MMP-9 expression through the p38 signaling pathway in cervical cancer cells

Diphenyl difluoroketone (EF-24), a synthetic curcumin analog, has enhanced bioavailability over curcumin. EF-24 acts more powerful bioactivity for anti-inflammatory and anti-cancer activity. However, the effects and mechanism of EF-24 on cervical cancer has not been fully investigated. Herein, this study evaluated the effects of EF-24 on TPA-induced cellular migration of cervical cancer. The results showed that EF-24 substantially reduced the cellular migration and cellular invasion of the HeLa and SiHa cells. Moreover, gelatin zymography, western blotting analyses and real-time PCR revealed that EF-24 suppressed Matrix metalloproteinase-9 (MMP-9) activity, protein expression and mRNA levels. Mechanistically, EF-24 inhibited the phosphorylation of the p38 signaling pathway. In conclusion, EF-24 inhibited TPA-induced cellular migration and cellular invasion of cervical cancer cell lines through modulating MMP-9 expression via downregulating signaling p38 pathway and EF-24 may have potential to serve as a chemopreventive agent of cervical cancer.

ARD1 stabilizes NRF2 through direct interaction and promotes colon cancer progression

AIMS

Aberrant overactivation/overexpression of NRF2 is implicated as a driving event in tumor progression, which has been attributed to its mutation or inactivation of the inhibitory protein, KEAP1. However, alternative mechanisms responsible for sustained activation of NRF2 are less understood.

MAIN METHODS

Human colon cancer cell lines and tissues obtained from colorectal cancer (CRC) patients were used. To examine the expression levels of ARD1 and NRF2, Western blot and immunofluorescence analyses were performed. To investigate the potential relevance of NRF2 and ARD1 to human CRC, NRF2 and ARD1 were individually silenced in human colon cancer cells (HCT-116) by transfection with their specific small interfering RNA (siRNA). To determine the functional role of ARD1 in NRF2 regulation, in situ proximate ligation, co-immunoprecipitation, nano-LC-ESI MS/MS, and in vitro acetylation assays were performed.

KEY FINDINGS

ARD1 knockdown in human colon cancer cell lines significantly reduced the protein levels of NRF2 without affecting its mRNA expression; however, silencing of NRF2 did not alter ARD1 protein expression. In addition, these two proteins were co-localized and physically interacted with each other both in human colon cancer cells (HCT-116) and human colon tumor tissues. Mechanistically, ARD1 overexpression increased the acetylation levels of NRF2. Moreover, an in vitro acetylation assay and mass spectrometric analysis demonstrated that ARD1 could directly acetylate NRF2. Ectopic expression of mutant forms of ARD1 with defective acetyltransferase activity reduced the stability of NRF2.

SIGNIFICANCE

In conclusion, ARD1 may potentiate the oncogenic function of NRF2 in human colon cancer by stabilizing this transcription factor.

Naa10p promotes cell invasiveness of esophageal cancer by coordinating the c-Myc and PAI1 regulatory axis

N-α-acetyltransferase 10 protein, Naa10p, is involved in various cellular functions impacting tumor progression. Due to its capacity to acetylate a large spectrum of proteins, both oncogenic and tumor-suppressive roles of Naa10p have been documented. Here, we report an oncogenic role of Naa10p in promoting metastasis of esophageal cancer. NAA10 is more highly expressed in esophageal cancer tissues compared to normal tissues. Higher NAA10 expression also correlates with poorer survival of esophageal cancer patients. We found that NAA10 expression was transcriptionally regulated by the critical oncogene c-Myc in esophageal cancer. Furthermore, activation of the c-Myc-Naa10p axis resulted in upregulated cell invasiveness of esophageal cancer. This increased cell invasiveness was also elucidated to depend on the enzymatic activity of Naa10p. Moreover, Naa10p cooperated with Naa15p to interact with the protease inhibitor, PAI1, and prevent its secretion. This inhibition of PAI1 secretion may derive from the N-terminal acetylation effect of the Naa10p/Naa15p complex. Our results establish the significance of Naa10p in driving metastasis in esophageal cancer by coordinating the c-Myc-PAI1 axis, with implications for its potential use as a prognostic biomarker and therapeutic target for esophageal cancer.

Construction of a synthetic methodology-based library and its application in identifying a GIT/PIX protein-protein interaction inhibitor

In recent years, the flourishing of synthetic methodology studies has provided concise access to numerous molecules with new chemical space. These compounds form a large library with unique scaffolds, but their application in hit discovery is not systematically evaluated. In this work, we establish a synthetic methodology-based compound library (SMBL), integrated with compounds obtained from our synthetic researches, as well as their virtual derivatives in significantly larger scale. We screen the library and identify small-molecule inhibitors to interrupt the protein-protein interaction (PPI) of GIT1/β-Pix complex, an unrevealed target involved in gastric cancer metastasis. The inhibitor 14-5-18 with a spiro[bicyclo[2.2.1]heptane-2,3'-indolin]-2'-one scaffold, considerably retards gastric cancer metastasis in vitro and in vivo. Since the PPI targets are considered undruggable as they are hard to target, the successful application illustrates the structural specificity of SMBL, demonstrating its potential to be utilized as compound source for more challenging targets.

N-α-Acetyltransferase 10 inhibits invasion and metastasis of oral squamous cell carcinoma via regulating Pirh2-p53 signalling pathway

N‐α‐Acetyltransferase 10 (NAA10) was reported to be involved in tumour invasion and metastasis in several of tumours. However, the role and mechanism of NAA10‐mediated invasion and metastasis in oral squamous cell carcinoma (OSCC) remains undetermined. Herein, our study showed that NAA10 inhibits cell migration and invasion in vitro and attenuates the xenograft tumorigenesis in nude mice. Mechanistically, we demonstrated that there is a physical interaction between NAA10 and RelA/p65 in OSCC cells, thereby preventing RelA/p65‐mediated transcriptional activation of Pirh2. Consequently, inhibition of Pirh2 increased p53 level and suppressed the expression of p53 downstream targets, matrix metalloprotein‐2 (MMP‐2) and MMP‐9. Therefore, NAA10 may function as a tumour metastasis suppressor in the progression of OSCC by targeting Pirh2‐p53 axis and might be a prognostic marker as well as a therapeutic target for OSCC.

Targeted Therapies in Lung Cancers: Current Landscape and Future Prospects

BACKGROUND

Lung cancer is the most common and malignant cancer worldwide. Targeted therapies have emerged as a promising treatment strategy for lung cancers.

OBJECTIVE

The objective of this study is to evaluate the current landscape of targets and finding promising targets for future new drug discovery for lung cancers by identifying the science-technology-clinical development pattern and mapping the interaction network of targets.

METHODS

Targets for cancers were classified into 3 groups based on a paper published in Nature. We search for scientific literature, patent documents and clinical trials of targets in Group 1 and Group 2 for lung cancers. Then, a target-target interaction network of Group 1 was constructed, and the science-technology-clinical(S-T-C) development patterns of targets in Group 1 were identified. Finally, based on the cluster distribution and the development pattern of targets in Group 1, interactions between the targets were employed to predict potential targets in Group 2 on drug development.

RESULTS

The target-target interaction(TTI)network of group 1 resulted in 3 clusters with different developmental stages. The potential targets in Group 2 are divided into 3 ranks. Level-1 is the first priority and level-3 is the last. Level-1 includes 16 targets, such as STAT3, CRKL, and PTPN11, that are mostly involved in signaling transduction pathways. Level-2 and level-3 contain 8 and 6 targets related to various biological functions.

CONCLUSION

This study will provide references for drug development in lung cancers, emphasizing that priorities should be given to targets in Level-1, whose mechanisms are worth further exploration.

Naa10p and IKKα interaction regulates EMT in oral squamous cell carcinoma via TGF-β1/Smad pathway

Epithelial‐mesenchymal transition (EMT) has been contributed to increase migration and invasion of cancer cells. However, the correlate of Naa10p and IKKα with EMT in oral squamous cell carcinoma (OSCC) is not yet fully understood. In our present study, we found N‐α‐acetyltransferase 10 protein (Naa10p) and IκB kinase α (IKKα) were abnormally abundant in oral squamous cell carcinoma (OSCC). Bioinformatic results indicate that the expression of Naa10p and IKKα is correlated with TGF‐β1/Smad and EMT‐related molecules. The Transwell migration, invasion, qRT‐PCR and Western blot assay indicated that Naa10p repressed OSCC cell migration, invasion and EMT, whereas IKKα promoted TGF‐β1–mediated OSCC cell migration, invasion and EMT. Mechanistically, Naa10p inhibited IKKα activation of Smad3 through the interaction with IKKα directly in OSCC cells after TGF‐β1 stimulation. Notably, knockdown of Naa10p reversed the IKKα‐induced change in the migration, invasion and EMT‐related molecules in OSCC cells after TGF‐β1 stimulation. These findings suggest that Naa10p interacted with IKKα mediates EMT in OSCC cells through TGF‐β1/Smad, a novel pathway for preventing OSCC.

Down-regulation of NAA10 mediates the neuroprotection induced by sevoflurane preconditioning via regulating ERK1/2 phosphorylation

OBJECTIVE

In the present study, the regulation mechanism of NAA10 (N-Alpha-Acetyltransferase 10) in sevoflurane preconditioning induced neuroprotective effect was explored.

METHODS

Firstly, si-NAA10 or negative control (NC) were constructed for cell transfection and injected into intracerebroventricular of rats. Oxygen-glucose deprivation/reperfusion (OGD/R) model in vitro and middle cerebral artery occlusion (MCAO) model in vivo were established to simulate cerebral I/R injury. QRT-PCR analysis and western blotting assay were performed to assess the expression of NAA10. TTC staining, neurological evaluation and cell counting kit-8 (CCK-8) were performed to evaluate the effect of NAA10 on sevoflurane induced neuroprotection. TUNEL assay and flow cytometry were used to detect the apoptosis in vivo and in vitro.

RESULTS

It showed that sevoflurane preconditioning increased the expression of NAA10 in MCAO rats. TTC staining, TUNEL assay and neurological evaluation results suggested that si-NAA10 attenuated the neuroprotective effect of sevoflurane preconditioning against MCAO. CCK-8 assay, flow cytometry, qRT-PCR and western blot results showed that NAA10 mediated sevoflurane preconditioning-induced neuroprotection in vitro. Furthermore, western blot results showed that down-regulation of NAA10 could reverse the attenuation of ERK1/2 phosphorylation induced by sevoflurane preconditioning in vivo or in vitro.

CONCLUSION

Down-regulation of NAA10 regulated ERK1/2 phosphorylation mediating sevoflurane preconditioning induced neuroprotective effects. The results revealed the regulatory mechanism of NAA10 in the neuroprotective effect of sevoflurane preconditioning.

Naa10p Enhances Chemosensitivity to Cisplatin in Oral Squamous Cell Carcinoma Cells

Background

This study aimed to investigate the function and underlying molecular mechanism of N-α-acetyltransferase 10 protein (Naa10p) in cisplatin (CDDP) chemosensitivity in oral squamous cell carcinoma (OSCC).

Methods

Salivary Naa10p levels in 76 OSCC patients undergoing CDDP-based chemotherapy were detected using enzyme-linked immunosorbent assay. Quantitative real-time polymerase chain reaction and Western blot were used to examine the expression of Naa10p in constructed CDDP-resistant OSCC cell (Cal-27/CDDP) lines and nude mouse model. In addition, the tumor volume and weight of nude mice were analyzed. Lentiviral system was employed to establish and identify OSCC cell lines with stable Naa10p interference or overexpression. MTT assay was used for drug sensitivity analysis. P-gp and Bcl-2 expression levels were tested by Western blot.

Results

Higher salivary Naa10p expression was present in the complete response/partial response group (n=46) compared to the stable disease/progressive disease group (n=30) in OSCC patients receiving chemotherapy treatment. Naa10p expression was down-regulated in Cal-27/CDDP cells and tissues. Naa10p overexpression significantly reduced the expression level of drug-resistant molecules. Naa10p was related to CDDP resistance and enhanced CDDP sensitivity in OSCC according to drug sensitivity analysis and nude mouse model experiments.

Conclusion

Naa10p plays a tumor suppressor gene role and is associated with CDDP resistance in OSCC. It can enhance CDDP sensitivity in OSCC and may be a potential target for OSCC chemotherapy.

Gut-derived Shewanella induces the differentially expressed proteins in leukocytes of Lampetra japonica

Lampreys, one of the most basal jawless vertebrates, are an excellent animal model for investigating vertebrate evolution, embryonic development, and the origin of adaptive immunity. Gut-derived Shewanella strain was isolated and then proved to induce adaptive immunity response in lampreys. Using Shewanella as the antigen, the effect of gut-derived Shewanella on lamprey leukocyte proteome was investigated via label-free liquid chromatography-tandem mass spectrometry for quantitative proteomics analysis. Twenty-five differentially expressed proteins in lamprey leukocytes were identified with significant differences. The differentially expressed proteins were associated with several biological processes. Among these proteins, the signal transducer and activator of transcription 3 (STAT3) was significantly upregulated in leukocytes after Shewanella immunization, indicating that lamprey STAT3 (L-STAT3) was involved in Shewanella-lamprey interactions. Expression pattern analysis revealed that L-STAT3 was mainly distributed in the cytoplasm and upregulated in other tissues after Shewanella immunization. Moreover, L-STAT3 overexpression could promote HEK-293 T and HeLa cell proliferation. However, the functions of L-STAT3 in the adaptive immune response of lamprey induced by gut-derived Shewanella remain to be explored. Overall, the identification of leukocyte proteins involved in Shewanella-lamprey interactions provides important information for understanding the variable lymphocyte receptor-based adaptive immune signal pathways in lampreys. SIGNIFICANCE: Lampreys are considered to be an excellent animal model for studying the origin and development of adaptive immune systems in vertebrates. Lampreys use variable lymphocyte receptors (VLRs) in recognizing antigens. However, the understanding of the VLR-based adaptive immune signal pathways in lampreys remains unclear. Intestinal bacteria could regulate the development of host immune systems. The attempts of inducing lamprey leukocyte differentially expressed proteins using the gut bacterial as the antigen will supply an promising avenue to explore the molecular mechanism of the intestinal bacteria interaction with it's host. Also, the identification of differentially expressed proteins involved in interactions between gut-derived Shewanella and lamprey will supply clues for understanding the variable lymphocyte receptor-based adaptive immune signal pathways in lampreys.

NAA10 as a New Prognostic Marker for Cancer Progression

N-α-acetyltransferase 10 (NAA10) is an acetyltransferase that acetylates both N-terminal amino acid and internal lysine residues of proteins. NAA10 is a crucial player to regulate cell proliferation, migration, differentiation, apoptosis, and autophagy. Recently, mounting evidence presented the overexpression of NAA10 in various types of cancer, including liver, bone, lung, breast, colon, and prostate cancers, and demonstrated a correlation of overexpressed NAA10 with vascular invasion and metastasis, thereby affecting overall survival rates of cancer patients and recurrence of diseases. This evidence all points NAA10 toward a promising biomarker for cancer prognosis. Here we summarize the current knowledge regarding the biological functions of NAA10 in cancer progression and provide the potential usage of NAA10 as a prognostic marker for cancer progression.

Stabilization of ADAM9 by N-α-acetyltransferase 10 protein contributes to promoting progression of androgen-independent prostate cancer

N-α-Acetyltransferase 10 protein (Naa10p) was reported to be an oncoprotein in androgen-dependent prostate cancer (PCa; ADPC) through binding and increasing transcriptional activity of the androgen receptor (AR). PCa usually progresses from an androgen-dependent to an androgen-independent stage, leading to an increase in the metastatic potential and an incurable malignancy. At present, the role of Naa10p in androgen-independent prostate cancer (AIPC) remains unclear. In this study, in silico and immunohistochemistry analyses showed that Naa10 transcripts or the Naa10p protein were more highly expressed in primary and metastatic PCa cancer tissues compared to adjacent normal tissues and non-metastatic cancer tissues, respectively. Knockdown and overexpression of Naa10p in AIPC cells (DU145 and PC-3M), respectively, led to decreased and increased cell clonogenic and invasive abilities in vitro as well as tumor growth and metastasis in AIPC xenografts. From the protease array screening, we identified a disintegrin and metalloprotease 9 (ADAM9) as a potential target of Naa10p, which was responsible for the Naa10p-induced invasion of AIPC cells. Naa10p can form a complex with ADAM9 to maintain ADAM9 protein stability and promote AIPC's invasive ability which were independent of its acetyltransferase activity. In contrast to the Naa10p-ADAM9 axis, ADAM9 exerted positive feedback regulation on Naa10p to modulate progression of AIPC in vitro and in vivo. Taken together, for the first time, our results reveal a novel cross-talk between Naa10p and ADAM9 in regulating the progression of AIPC. Disruption of Naa10p-ADAM9 interactions may be a potential intervention for AIPC therapy.

Loss of ϐPix Causes Defects in Early Embryonic Development, and Cell Spreading and PlateletDerived Growth Factor-Induced Chemotaxis in Mouse Embryonic Fibroblasts

βPix is a guanine nucleotide exchange factor for the Rho family small GTPases, Rac1 and Cdc42. It is known to regulate focal adhesion dynamics and cell migration. However, the in vivo role of βPix is currently not well understood. Here, we report the production and characterization of βPix-KO mice. Loss of βPix results in embryonic lethality accompanied by abnormal developmental features, such as incomplete neural tube closure, impaired axial rotation, and failure of allantoischorion fusion. We also generated βPix-KO mouse embryonic fibroblasts (MEFs) to examine βPix function in mouse fibroblasts. βPix-KO MEFs exhibit decreased Rac1 activity, and defects in cell spreading and platelet-derived growth factor (PDGF)-induced ruffle formation and chemotaxis. The average size of focal adhesions is increased in βPix-KO MEFs. Interestingly, βPix-KO MEFs showed increased motility in random migration and rapid wound healing with elevated levels of MLC2 phosphorylation. Taken together, our data demonstrate that βPix plays essential roles in early embryonic development, cell spreading, and cell migration in fibroblasts.

Structure and Mechanism of Acetylation by the N-Terminal Dual Enzyme NatA/Naa50 Complex

NatA co-translationally acetylates the N termini of over 40% of eukaryotic proteins and can associate with another catalytic subunit, Naa50, to form a ternary NatA/Naa50 dual enzyme complex (also called NatE). The molecular basis of association between Naa50 and NatA and the mechanism for how their association affects their catalytic activities in yeast and human are poorly understood. Here, we determined the X-ray crystal structure of yeast NatA/Naa50 as a scaffold to understand coregulation of NatA/Naa50 activity in both yeast and human. We find that Naa50 makes evolutionarily conserved contacts to both the Naa10 and Naa15 subunits of NatA. These interactions promote catalytic crosstalk within the human complex, but do so to a lesser extent in the yeast complex, where Naa50 activity is compromised. These studies have implications for understanding the role of the NatA/Naa50 complex in modulating the majority of the N-terminal acetylome in diverse species.

Inverse correlation between Naa10p and Pirh2 expression and the combined prognostic value in oral squamous cell carcinoma patients

BACKGROUND

This study aims to explore the associations between N-α-acetyltransferase 10 protein (Naa10p) and p53-induced protein with a RING-H2 domain (Pirh2) expression and clinicopathological characteristics in oral squamous cell carcinoma (OSCC).

METHODS

Immunohistochemistry was performed to detect Naa10p and Pirh2 levels containing 118 OSCC specimens, and additional analyses were used to determine correlations between Naa10p and Pirh2 expressions, generate survival curves, and perform univariate and multivariate statistical analyses. Further, quantitative real-time PCR (qRT-PCR) and western blot were employed to examine Naa10p and Pirh2 expression level in OSCC patients' samples. We further validated the result using RNAseq data from The Cancer Genome Atlas (TCGA) and mRNA array data from GSE31056 and GSE30784.

RESULTS

Naa10p and Pirh2 are overexpression, and the protein level of Naa10p was negatively correlated with that of Pirh2 in OSCC tissues. Multivariate Cox proportional hazard regression analysis showed that positive Naa10p expression and negative Pirh2 expression were both independent good prognostic factors for OSCC patients. Furthermore, the Naa10p-positive/Pirh2-negative group has the best prognosis among all OSCC patients. Results from qRT-PCR showed the higher expression level of Naa10 and lower expression level of Pirh2 in tumor tissues than adjacent normal tissues. TCGA database and data from GSE31056 and GSE30784 showed the similar result. The correlation analysis showed that the mRNA level of Naa10 was negatively correlated that of Pirh2.

CONCLUSION

The expression of Naa10p is negatively correlated with that of Pirh2, and positive Naa10p and negative Pirh2 might be independent biomarkers for better OSCC prognoses.

The N-end rule pathway enzyme Naa10 supports epiblast specification in mouse embryonic stem cells by modulating FGF/MAPK

N-terminal acetylation (Nt-acetylation) refers to the acetylation of the free α-amino group at the N-terminus of a polypeptide. While the effects of Nt-acetylation are multifaceted, its most known function is in the acetylation-dependent N-end rule protein degradation pathway (Ac/N-end rule pathway), where Nt-acetylation is recognized as a degron by designated E3 ligases, eventually leading to target degradation by the ubiquitin-proteasome system. Naa10 is the catalytic subunit of the major Nt-acetylation enzyme NatA, which Nt-acetylates proteins whose second amino acid has a small side chain. In humans, NAA10 is the responsible mutated gene in Ogden syndrome and is thought to play important roles in development. However, it is unclear how the Ac/N-end rule pathway affects the differentiation ability of mouse embryonic stem cells (mESCs). We hypothesized that the balance of pluripotency factors may be maintained by the Ac/N-end rule pathway. Thus, we established Naa10 knockout mESCs to test this hypothesis. We found that Naa10 deficiency attenuated differentiation towards the epiblast lineage, deviating towards primitive endoderm. However, this was not caused by disturbing the balance of pluripotency factors, rather by augmenting FGF/MAPK signaling.

Co-translational, Post-translational, and Non-catalytic Roles of N-Terminal Acetyltransferases

Recent studies of N-terminal acetylation have identified new N-terminal acetyltransferases (NATs) and expanded the known functions of these enzymes beyond their roles as ribosome-associated co-translational modifiers. For instance, the identification of Golgi- and chloroplast-associated NATs shows that acetylation of N termini also happens post-translationally. In addition, we now appreciate that some NATs are highly specific; for example, a dedicated NAT responsible for post-translational N-terminal acetylation of actin was recently revealed. Other studies have extended NAT function beyond Nt acetylation, including functions as lysine acetyltransferases (KATs) and non-catalytic roles. Finally, emerging studies emphasize the physiological relevance of N-terminal acetylation, including roles in calorie-restriction-induced longevity and pathological α-synuclein aggregation in Parkinson's disease. Combined, the NATs rise as multifunctional proteins, and N-terminal acetylation is gaining recognition as a major cellular regulator.

Mir20a/106a-WTX axis regulates RhoGDIa/CDC42 signaling and colon cancer progression

Wilms tumor gene on the X chromosome (WTX) is a putative tumor suppressor gene in Wilms tumor, but its expression and functions in other tumors are unclear. Colorectal cancer (CRC) is the third leading cause of cancer-related deaths in women and the second leading cause in men in the United States. We demonstrated that WTX frequently lost in CRC which was highly correlated with cell proliferation, tumor invasion and metastasis. Mechanistically, WTX loss disrupts the interaction between RhoGDIα and CDC42 by losing of the binding with RhoGDIα and triggers the activation of CDC42 and its downstream cascades, which promotes CRC development and liver metastasis. The aberrant upregulation of miR-20a/miR-106a were identified as the reason of WTX loss in CRC both in vivo and in vitro. These study defined the mechanism how miR-20a/miR-106a-mediated WTX loss regulates CRC progression and metastasis, and provided a potential therapeutic target for preventing CRC progression.

ARD1 contributes to IKKβ-mediated breast cancer tumorigenesis

The expression of IκB kinase β (IKKβ) promotes the growth of breast cancer cells. Meanwhile, IKKβ mediates the phosphorylation and subsequent degradation of arrest-defective protein 1 (ARD1). However, the relationship between IKKβ and ARD1 in the occurrence of breast cancer has not been reported. In this study, we found that IKKβ not only acts directly on mammalian target of rapamycin (mTOR) activity but also indirectly acts on mTOR activity through posttranscriptional modification of ARD1, thereby effectively promoting the growth of breast cancer cells. ARD1 prevents mTOR activity and breast cancer cell growth by stabilizing tuberous sclerosis complex 2 (TSC2) to induce autophagy. Moreover, acetylation of heat shock protein 70 (Hsp70) also contributes to ARD1-mediated autophagy. Therefore, upstream IKKβ can further promote the occurrence of breast cancer by mediating the function of ARD1.

NAA10-related syndrome

NAA10-related syndrome is an X-linked condition with a broad spectrum of findings ranging from a severe phenotype in males with p.Ser37Pro in NAA10, originally described as Ogden syndrome, to the milder NAA10-related intellectual disability found with different variants in both males and females. Although developmental impairments/intellectual disability may be the presenting feature (and in some cases the only finding), many individuals have additional cardiovascular, growth, and dysmorphic findings that vary in type and severity. Therefore, this set of disorders has substantial phenotypic variability and, as such, should be referred to more broadly as NAA10-related syndrome. NAA10 encodes an enzyme NAA10 that is certainly involved in the amino-terminal acetylation of proteins, alongside other proposed functions for this same protein. The mechanistic basis for how variants in NAA10 lead to the various phenotypes in humans is an active area of investigation, some of which will be reviewed herein.

A detailed overview of a rare X-linked hereditary disorder gives clinicians a resource for making an informed diagnosis based on genetic data and developmental abnormalities. Around 80% of all human proteins are modified on their amino terminus via tagging with an acetyl group, and the NAA10 enzyme plays a major role in this process. Mutations in the gene encoding NAA10 produce severe neurological and cardiovascular effects. Yiyang Wu and Gholson Lyon at the Cold Spring Harbor Laboratory, Woodbury, USA, have reviewed current research to facilitate accurate identification of ‘NAA10-related syndrome’. Since this gene resides on the X chromosome, mutations strongly affect males, although some female carriers also show symptoms. NAA10-related syndrome is exceedingly rare, with only 26 cases reported to date, and the researchers describe both known causative mutations and unrelated disorders that produce similar developmental defects.

ARD1/NAA10 in hepatocellular carcinoma: pathways and clinical implications

Hepatocellular carcinoma (HCC), a representative example of a malignancy with a poor prognosis, is characterized by high mortality because it is typically in an advanced stage at diagnosis and leaves very little hepatic functional reserve. Despite advances in medical and surgical techniques, there is no omnipotent tool that can diagnose HCC early and then cure it medically or surgically. Several recent studies have shown that a variety of pathways are involved in the development, growth, and even metastasis of HCC. Among a variety of cytokines or molecules, some investigators have suggested that arrest-defective 1 (ARD1), an acetyltransferase, plays a key role in the development of malignancies. Although ARD1 is thought to be centrally involved in the cell cycle, cell migration, apoptosis, differentiation, and proliferation, the role of ARD1 and its potential mechanistic involvement in HCC remain unclear. Here, we review the present literature on ARD1. First, we provide an overview of the essential structure, functions, and molecular mechanisms or pathways of ARD1 in HCC. Next, we discuss potential clinical implications and perspectives. We hope that, by providing new insights into ARD1, this review will help to guide the next steps in the development of markers for the early detection and prognosis of HCC.

A protein that is highly expressed in cancer with extensive blood vessel development may provide a potential biomarker for early-stage liver cancer. Liver cancer is often not diagnosed until it is advanced and is also hard to be cured despite of advances in treatment, meaning patients often die from the disease. No tools for early detection or prognosis prediction exist, and scientists are keen to find useful biomarker molecules. Young-Hwa Chung at the University of Ulsan College of Medicine, Asan Medical Center, Seoul, and co-workers in South Korea reviewed recent research into one possible cancer-related protein, arrest-defective 1 (ARD1), known to be highly expressed in certain cancers and possibly associated with poor prognosis. While ARD1 appears to regulate pathways critical to cancer progression and promote cancer cell invasiveness, further in-depth investigations are needed to clarify its specific role in liver cancer.

Spotlight on protein N-terminal acetylation

N-terminal acetylation (Nt-acetylation) is a widespread protein modification among eukaryotes and prokaryotes alike. By appending an acetyl group to the N-terminal amino group, the charge, hydrophobicity, and size of the N-terminus is altered in an irreversible manner. This alteration has implications for the lifespan, folding characteristics and binding properties of the acetylated protein. The enzymatic machinery responsible for Nt-acetylation has been largely described, but significant knowledge gaps remain. In this review, we provide an overview of eukaryotic N-terminal acetyltransferases (NATs) and the impact of Nt-acetylation. We also discuss other functions of known NATs and outline methods for studying Nt-acetylation.

N-α-acetyltransferase 10 protein promotes metastasis by stabilizing matrix metalloproteinase-2 protein in human osteosarcomas

N-α-Acetyltransferase 10 protein (Naa10p) mediates N-terminal acetylation of nascent proteins. Oncogenic or tumor suppressive roles of Naa10p were reported in cancers. Here, we report an oncogenic role of Naa10p in promoting metastasis of osteosarcomas. Higher NAA10 transcripts were observed in metastatic osteosarcoma tissues compared to non-metastatic tissues and were also correlated with a worse prognosis of patients. Knockdown and overexpression of Naa10p in osteosarcoma cells respectively led to decreased and increased cell migratory/invasive abilities. Re-expression of Naa10p, but not an enzymatically inactive mutant, relieved suppression of the invasive ability in vitro and metastasis in vivo imposed by Naa10p-knockdown. According to protease array screening, we identified that matrix metalloproteinase (MMP)-2 was responsible for the Naa10p-induced invasive phenotype. Naa10p was directly associated with MMP-2 protein through its acetyltransferase domain and maintained MMP-2 protein stability via NatA complex activity. MMP-2 expression levels were also significantly correlated with Naa10p levels in osteosarcoma tissues. These results reveal a novel function of Naa10p in the regulation of cell invasiveness by preventing MMP-2 protein degradation that is crucial during osteosarcoma metastasis.

Truncating Variants in NAA15 Are Associated with Variable Levels of Intellectual Disability, Autism Spectrum Disorder, and Congenital Anomalies

N-alpha-acetylation is a common co-translational protein modification that is essential for normal cell function in humans. We previously identified the genetic basis of an X-linked infantile lethal Mendelian disorder involving a c.109T>C (p.Ser37Pro) missense variant in NAA10, which encodes the catalytic subunit of the N-terminal acetyltransferase A (NatA) complex. The auxiliary subunit of the NatA complex, NAA15, is the dimeric binding partner for NAA10. Through a genotype-first approach with whole-exome or genome sequencing (WES/WGS) and targeted sequencing analysis, we identified and phenotypically characterized 38 individuals from 33 unrelated families with 25 different de novo or inherited, dominantly acting likely gene disrupting (LGD) variants in NAA15. Clinical features of affected individuals with LGD variants in NAA15 include variable levels of intellectual disability, delayed speech and motor milestones, and autism spectrum disorder. Additionally, mild craniofacial dysmorphology, congenital cardiac anomalies, and seizures are present in some subjects. RNA analysis in cell lines from two individuals showed degradation of the transcripts with LGD variants, probably as a result of nonsense-mediated decay. Functional assays in yeast confirmed a deleterious effect for two of the LGD variants in NAA15. Further supporting a mechanism of haploinsufficiency, individuals with copy-number variant (CNV) deletions involving NAA15 and surrounding genes can present with mild intellectual disability, mild dysmorphic features, motor delays, and decreased growth. We propose that defects in NatA-mediated N-terminal acetylation (NTA) lead to variable levels of neurodevelopmental disorders in humans, supporting the importance of the NatA complex in normal human development.

NAA10 dysfunction with normal NatA-complex activity in a girl with non-syndromic ID and a de novo NAA10 p.(V111G) variant - a case report

Background

The NAA10-NAA15 (NatA) protein complex is an N-terminal acetyltransferase responsible for acetylating ~ 40% of eukaryotic proteins. In recent years, NAA10 variants have been found in patients with an X-linked developmental disorder called Ogden syndrome in its most severe form and, in other familial or de novo cases, with variable degrees of syndromic intellectual disability (ID) affecting both sexes.

Case presentation

Here we report and functionally characterize a novel and de novo NAA10 (NM_003491.3) c.332 T > G p.(V111G) missense variant, that was detected by trio-based whole exome sequencing in an 11 year old girl with mild/moderate non-syndromic intellectual disability. She had delayed motor and language development, but normal behavior without autistic traits. Her blood leukocyte X-inactivation pattern was within normal range (80/20). Functional characterization of NAA10-V111G by cycloheximide chase experiments suggests that NAA10-V111G has a reduced stability compared to NAA10-WT, and in vitro acetylation assays revealed a reduced enzymatic activity of monomeric NAA10-V111G but not for NAA10-V111G in complex with NAA15 (NatA enzymatic activity).

Conclusions

We show that NAA10-V111G has a reduced stability and monomeric catalytic activity, while NatA function remains unaltered. This is the first example of isolated NAA10 dysfunction in a case of ID, suggesting that the syndromic cases may also require a degree of compromised NatA function.

Acetylation of androgen receptor by ARD1 promotes dissociation from HSP90 complex and prostate tumorigenesis

Prostate cancer is an androgen receptor (AR)-driven disease and post-translational modification of AR is critical for AR activation. We previously reported that Arrest-defective protein 1 (ARD1) is an oncoprotein in prostate cancer. It acetylates and activates AR to promote prostate tumorigenesis. However, the ARD1-targeted residue within AR and the mechanisms of the acetylation event in prostate tumorigenesis remained unknown. In this study, we show that ARD1 acetylates AR at lysine 618 (K618) in vitro and in vivo. An AR construct with the charged lysine substitution by arginine (AR-618R) reduces RNA Pol II binding, AR transcriptional activity, prostate cancer cell growth, and xenograft tumor formation due to attenuation of AR nuclear translocation, whereas, construct mimicking neutral polar substitution acetylation at K618 by glutamine (AR-618Q) enhanced these effects beyond that of the wild-type AR. Mechanistically, ARD1 forms a ternary complex with AR and HSP90 in vitro and in vivo. Expression of ARD1 increases levels of AR acetylation and AR-HSP90 dissociation in a dose dependent manner. Moreover, the AR acetylation defective K618R mutant is unable to dissociate from HSP90 while the HSP90-dissociated AR is acetylated following ligand exposure. This work identifies a new mechanism for ligand-induced AR-HSP90 dissociation and AR activation. Targeting ARD1-mediated AR acetylation may be a potent intervention for AR-dependent prostate cancer therapy.

Identification of PA28β as a potential novel biomarker in human esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is one of the most common and serious malignancies in China. However, the exact mechanisms of tumor formation and progression are unclear. As late diagnosis and poor therapeutic efficacy result in lower survival rates, identifying biomarkers for early detection, prognostic evaluation, and recurrence monitoring of ESCC is necessary. Here we analyzed 10 protein expression profiles of ESCC core tissues and paired normal esophageal epithelial tissues using two-dimensional gel electrophoresis. We excised 29 protein spots with two-fold or greater differential expression between cancer and normal tissues and identified them using matrix-assisted laser desorption/ionization-time-of-flight/time-of-flight mass spectrometry. The role of PA28β in ESCC cell was confirmed using cell growth, colony formation and soft agar in TE-1 cells pre- and post- PA28β transfection. Compared to their expression in the adjacent normal epithelia, 12 proteins, including transgelin (TAGLN), were upregulated in ESCC tissues; 17 proteins, including proteasome activator 28-beta subunit (PA28β), were downregulated (p < 0.05). Western blotting and immunohistochemistry confirmed that PA28β was significantly underexpressed in ESCC tissues. The functional assays demonstrate that PA28β inhibited cell growth, proliferation and malignancy of TE-1 cells. Among the differentially expressed proteins, PA28β is a potential tumor inhibitor.

NatD promotes lung cancer progression by preventing histone H4 serine phosphorylation to activate Slug expression

N-α-acetyltransferase D (NatD) mediates N-α-terminal acetylation (Nt-acetylation) of histone H4 known to be involved in cell growth. Here we report that NatD promotes the migratory and invasive capabilities of lung cancer cells in vitro and in vivo. Depletion of NatD suppresses the epithelial-to-mesenchymal transition (EMT) of lung cancer cells by directly repressing the expression of transcription factor Slug, a key regulator of EMT. We found that Nt-acetylation of histone H4 antagonizes histone H4 serine 1 phosphorylation (H4S1ph), and that downregulation of Nt-acetylation of histone H4 facilitates CK2α binding to histone H4 in lung cancer cells, resulting in increased H4S1ph and epigenetic reprogramming to suppress Slug transcription to inhibit EMT. Importantly, NatD is commonly upregulated in primary human lung cancer tissues where its expression level correlates with Slug expression, enhanced invasiveness, and poor clinical outcomes. These findings indicate that NatD is a crucial epigenetic modulator of cell invasion during lung cancer progression.

NatD is an acetyltransferase responsible for N-α-terminal acetylation of the histone H4 and H2A and has been linked to cell growth. Here the authors show that NatD-mediated acetylation of histone H4 serine 1 competes with the phosphorylation by CK2α at the same residue thus leading to the upregulation of Slug and tumor progression.

Cell Division Cycle 42 plays a Cell type-Specific role in Lung Tumorigenesis

Cell division cycle 42 (CDC42) plays important roles in polarity establishment and maintenance as well as cell cycle progression and cell division. Although disruption of cell polarity is a prerequisite in epithelial tumor initiation, the roles of CDC42 in tumorigenesis are still poorly understood. Here we find that Cdc42 deficiency inhibits the Kras^G12D-induced lung alveoli tumor formation, while conversely promotes bronchiole tumor formation in mice. Bronchial Cdc42 loss destroys contact inhibition potentially through cell polarity disruption, and results in increased tumor formation. In contrast, deletion of Cdc42 in alveoli cells prevents Kras^G12D-induced cell proliferation, which leads to reduced tumor formation. Further analyses of clinical specimens uncover a significant positive correlation between CDC42 and type II alveolar epithelial cells marker SP-A, indicating the potential importance of CDC42 in this specific subset of lung cancer. Collectively, we identify the lineage-specific function of CDC42 in lung tumorigenesis potentially through the regulation of cell polarity integrity.

Identification of Nucleobindin-2 as a Potential Biomarker for Breast Cancer Metastasis Using iTRAQ-based Quantitative Proteomic Analysis

Metastasis is a lethal step in the progression of breast cancer. None of the metastasis-associated biomarkers identified up to now has a definite prognostic value in breast cancer patients. This study was designed to identify biomarkers for breast cancer metastasis and predictors of the prognosis of breast cancer patients. The differentially expressed proteins between 23 paired primary breast tumor and metastatic lymph nodes were identified by quantitative iTRAQ proteomic analysis. Immunohistochemistry was applied to locate and assess the expression of NUCB2 in paired primary breast tumor and metastatic lymph node tissues (n = 106). The relationship between NUCB2 expression and the clinicopathological characteristics of breast cancer patients (n = 189) were analyzed by χ² test. Kaplan-Meier analysis and Cox hazard regression analysis were utilized to investigate the relationship between its expression and prognosis of breast cancer patients. The iTRAQ proteomic results showed that 4,837 confidential proteins were identified, 643 of which were differentially expressed in the primary breast cancer tissues and the paired metastatic lymph nodes. NUCB2 protein was found decreased in paired metastatic lymph nodes (P = 0.000), with the positive expression rate being 82% in primary breast cancer tissues and 47% in paired metastatic lymph nodes, respectively. According to Kaplan-Meier analysis, the overall survival time of patients with positive expression of NUCB2 protein were shorter than those with negative NUCB2 expression (P = 0.004). Cox regression model suggested that NUCB2 was a risk factor of breast cancer patients (P = 0.045, RR = 1.854). We conclude that NUCB2 can be used as a potential biomarker for breast cancer metastasis and a prognostic predictor of breast cancer patients.

NatB-mediated protein N-α-terminal acetylation is a potential therapeutic target in hepatocellular carcinoma

The identification of new targets for systemic therapy of hepatocellular carcinoma (HCC) is an urgent medical need. Recently, we showed that hNatB catalyzes the N-α-terminal acetylation of 15% of the human proteome and that this action is necessary for proper actin cytoskeleton structure and function. In tumors, cytoskeletal changes influence motility, invasion, survival, cell growth and tumor progression, making the cytoskeleton a very attractive antitumor target. Here, we show that hNatB subunits are upregulated in in over 59% HCC tumors compared to non-tumor tissue and that this upregulation is associated with microscopic vascular invasion. We found that hNatB silencing blocks proliferation and tumor formation in HCC cell lines in association with hampered DNA synthesis and impaired progression through the S and the G2/M phases. Growth inhibition is mediated by the degradation of two hNatB substrates, tropomyosin and CDK2, which occurs when these proteins lack N-α-terminal acetylation. In addition, hNatB inhibition disrupts the actin cytoskeleton, focal adhesions and tight/adherens junctions, abrogating two proliferative signaling pathways, Hippo/YAP and ERK1/2. Therefore, inhibition of NatB activity represents an interesting new approach to treating HCC by blocking cell proliferation and disrupting actin cytoskeleton function.

The scaffold protein p140Cap limits ERBB2-mediated breast cancer progression interfering with Rac GTPase-controlled circuitries

The docking protein p140Cap negatively regulates tumour cell features. Its relevance on breast cancer patient survival, as well as its ability to counteract relevant cancer signalling pathways, are not fully understood. Here we report that in patients with ERBB2-amplified breast cancer, a p140Cap-positive status associates with a significantly lower probability of developing a distant event, and a clear difference in survival. p140Cap dampens ERBB2-positive tumour cell progression, impairing tumour onset and growth in the NeuT mouse model, and counteracting epithelial mesenchymal transition, resulting in decreased metastasis formation. One major mechanism is the ability of p140Cap to interfere with ERBB2-dependent activation of Rac GTPase-controlled circuitries. Our findings point to a specific role of p140Cap in curbing the aggressiveness of ERBB2-amplified breast cancers and suggest that, due to its ability to impinge on specific molecular pathways, p140Cap may represent a predictive biomarker of response to targeted anti-ERBB2 therapies.

p140Cap adaptor proteins interfere with adhesion and growth factor-dependent signalling in cancer cells but the mechanisms are unclear. Here the authors show that p140Cap interferes with ERBB2-dependent activation of Rac GTPase-controlled circuitries reducing metastasis and cancer progression.

Epigenomic Regulation of Androgen Receptor Signaling: Potential Role in Prostate Cancer Therapy

Androgen receptor (AR) signaling remains the major oncogenic pathway in prostate cancer (PCa). Androgen-deprivation therapy (ADT) is the principle treatment for locally advanced and metastatic disease. However, a significant number of patients acquire treatment resistance leading to castration resistant prostate cancer (CRPC). Epigenetics, the study of heritable and reversible changes in gene expression without alterations in DNA sequences, is a crucial regulatory step in AR signaling. We and others, recently described the technological advance Chem-seq, a method to identify the interaction between a drug and the genome. This has permitted better understanding of the underlying regulatory mechanisms of AR during carcinogenesis and revealed the importance of epigenetic modifiers. In screening for new epigenomic modifiying drugs, we identified SD-70, and found that this demethylase inhibitor is effective in CRPC cells in combination with current therapies. The aim of this review is to explore the role of epigenetic modifications as biomarkers for detection, prognosis, and risk evaluation of PCa. Furthermore, we also provide an update of the recent findings on the epigenetic key processes (DNA methylation, chromatin modifications and alterations in noncoding RNA profiles) involved in AR expression and their possible role as therapeutic targets.

microRNA-342-5p and miR-608 inhibit colon cancer tumorigenesis by targeting NAA10

miRNAs have been shown to play pivotal roles in the establishment and progression of colon cancer, but their underlying mechanisms are not fully understood. N-acetyltransferase NAA10 participates in many cellular processes, including tumorigenesis. Here we showed that miR-342-5p and miR-608 suppressed the tumorigenesis of colon cancer cells in vitro and in vivo by targeting NAA10 mRNA for degradation. Overexpression of miR-342-5p or miR-608 decreased NAA10 mRNA and protein levels and thereby suppressed cell proliferation, migration, and cell-cycle progression, as well as promoted apoptosis in SW480 and SW620 cells. More importantly, miR-342-5p and miR-608 significantly decreased the tumorigenic capacity of SW480 and SW620 cells in a mouse xenograft model. We also observed an inverse correlation between the expression of NAA10 and that of both miRNAs. Our results implicate miR-342-5p and miR-608 in colon cancer development and unveil the underlying mechanism of this phenomenon, which involves NAA10.

GIT1 promotes lung cancer cell metastasis through modulating Rac1/Cdc42 activity and is associated with poor prognosis

G-protein-coupled receptor kinase interacting protein 1 (GIT1) is participated in cell movement activation, which is a fundamental process during tissue development and cancer progression. GIT1/PIX forming a functional protein complex that contributes to Rac1/Cdc42 activation, resulting in increasing cell mobility. Although the importance of Rac1/Cdc42 activation is well documented in cancer aggressiveness, the clinical importance of GIT1 remains largely unknown. Here, we investigated the clinical significance of GIT1 expression in non-small-cell lung cancer (NSCLC) and also verified the importance of GIT1-Rac1/Cdc42 axis in stimulating NSCLC cell mobility. The result indicated higher GIT1 expression patients had significantly poorer prognoses in disease-free survival (DFS) and overall survival (OS) compared with lower GIT1 expression patients. Higher GIT1 expression was an independent prognostic factor by multivariate analysis and associated with migration/invasion of NSCLC cells in transwell assay. In vivo studies indicated that GIT1 promotes metastasis of NSCLC cells. Finally, GIT1 was found to stimulate migration/invasion by altering the activity of Rac1/Cdc42 in NSCLC cells. Together, the GIT1 expression is associated with poor prognosis in patients with NSCLC. GIT1 is critical for the invasiveness of NSCLC cells through stimulating the activity of Rac1/Cdc42.

Depletion of histone N-terminal-acetyltransferase Naa40 induces p53-independent apoptosis in colorectal cancer cells via the mitochondrial pathway

Protein N-terminal acetylation is an abundant post-translational modification in eukaryotes implicated in various fundamental cellular and biochemical processes. This modification is catalysed by evolutionarily conserved N-terminal acetyltransferases (NATs) whose deregulation has been linked to cancer development and thus, are emerging as useful diagnostic and therapeutic targets. Naa40 is a highly selective NAT that acetylates the amino-termini of histones H4 and H2A and acts as a sensor of cell growth in yeast. In the present study, we examine the role of Naa40 in cancer cell survival. We demonstrate that depletion of Naa40 in HCT116 and HT-29 colorectal cancer cells decreases cell survival by enhancing apoptosis, whereas Naa40 reduction in non-cancerous mouse embryonic fibroblasts has no effect on cell viability. Specifically, Naa40 knockdown in colon cancer cells activates the mitochondrial caspase-9-mediated apoptotic cascade. Consistent with this, we show that caspase-9 activation is required for the induced apoptosis because treatment of cells with an irreversible caspase-9 inhibitor impedes apoptosis when Naa40 is depleted. Furthermore, the effect of Naa40-depletion on cell-death is mediated through a p53-independent mechanism since p53-null HCT116 cells still undergo apoptosis upon reduction of the acetyltransferase. Altogether, these findings reveal an anti-apoptotic role for Naa40 and exhibit its potential as a therapeutic target in colorectal cancers.