Nicotinamide N-methyltransferase overexpression is associated with Akt phosphorylation and indicates worse prognosis in patients with nasopharyngeal carcinoma

Knockdown of nicotinamide N-methyltransferase suppresses proliferation, migration, and chemoresistance of Merkel cell carcinoma cells in vitro

Merkel cell carcinoma (MCC) is an aggressive skin cancer, with a propensity for early metastasis. Therefore, early diagnosis and the identification of novel targets become fundamental. The enzyme nicotinamide N-methyltransferase (NNMT) catalyzes the reaction of N-methylation of nicotinamide and other analogous compounds. Although NNMT overexpression was reported in many malignancies, the significance of its dysregulation in cancer cell phenotype was partly clarified. Several works demonstrated that NNMT promotes cancer cell proliferation, migration, and chemoresistance. In this study, we investigated the possible involvement of this enzyme in MCC. Preliminary immunohistochemical analyses were performed to evaluate NNMT expression in MCC tissue specimens. To explore the enzyme function in tumor cell metabolism, MCC cell lines have been transfected with plasmids encoding for short hairpin RNAs (shRNAs) targeting NNMT mRNA. Preliminary immunohistochemical analyses showed elevated NNMT expression in MCC tissue specimens. The effect of enzyme downregulation on cell proliferation, migration, and chemosensitivity was then evaluated through MTT, trypan blue, and wound healing assays. Data obtained clearly demonstrated that NNMT knockdown is associated with a decrease of cell proliferation, viability, and migration, as well as with enhanced sensitivity to treatment with chemotherapeutic drugs. Taken together, these results suggest that NNMT could represent an interesting MCC biomarker and a promising target for targeted anti-cancer therapy.

Long Non-Coding RNA Small Nucleolar RNA Host Gene 4 Induced by Transcription Factor SP1 Promoted the Progression of Nasopharyngeal Carcinoma Through Modulating microRNA-510-5p/Centromere Protein F Axis

Long non-coding RNAs (LncRNAs) are implicated with tumorigenesis and the development of nasopharyngeal carcinoma (NPC). Previous studies suggested that long non-coding RNA small nucleolar RNA host gene 4 (SNHG4) exerted oncogenic roles in various cancers. However, the function and molecular mechanism of SNHG4 in NPC have not been investigated. In our study, it was confirmed that the SNHG4 level was enriched in NPC tissues and cells. Functional assays indicated that SNHG4 depletion inhibited the proliferation and metastasis but promoted apoptosis of NPC cells. Furthermore, we identified miR-510-5p as a downstream gene of SNHG4 in NPC cells and SNHG4 upregulated CENPF expression by binding to miR-510-5p. Moreover, there was a positive (or negative) association between CENPF and SNHG4 (or miR-510-5p) expression in NPC. In addition, rescue experiments verified that CENPF overexpression or miR-510-5p silencing abrogated inhibitory effects on NPC tumorigenesis caused by SNHG4 deficiency. The study demonstrated that SNHG4 promoted NPC progression via miR-510-5p/CENPF axis, providing a novel potential therapeutic target for NPC treatments.

Nicotinamide N-Methyltransferase as Promising Tool for Management of Gastrointestinal Neoplasms

Gastrointestinal (GI) neoplasms include esophageal, gastric, colorectal, hepatic, and pancreatic cancers. They are characterized by asymptomatic behavior, being responsible for diagnostic delay. Substantial refractoriness to chemo- and radiotherapy, exhibited by late-stage tumors, contribute to determine poor patient outcome. Therefore, it is of outmost importance to identify new molecular targets for the development of effective therapeutic strategies. In this study, we focused on the enzyme nicotinamide N-methyltransferase (NNMT), which catalyzes the N-methylation reaction of nicotinamide and whose overexpression has been reported in numerous neoplasms, including GI cancers. The aim of this review was to report data illustrating NNMT involvement in these tumors, highlighting its contribution to tumor cell phenotype. Cited works clearly demonstrate the interesting potential use of enzyme level determination for both diagnostic and prognostic purposes. NNMT was also found to positively affect cell viability, proliferation, migration, and invasiveness, contributing to sustain in vitro and in vivo tumor growth and metastatic spread. Moreover, enzyme upregulation featuring tumor cells was significantly associated with enhancement of resistance to treatment with chemotherapeutic drugs. Taken together, these results strongly suggest the possibility to target NNMT for setup of molecular-based strategies to effectively treat GI cancers.

Tumor stromal nicotinamide N-methyltransferase overexpression as a prognostic biomarker for poor clinical outcome in early-stage colorectal cancer

In a quest for prognostic biomarkers in early-stage colorectal cancer, we investigated NNMT (nicotinamide N-methyltransferase) in large cohorts of patients. Immunohistochemical examination of 679 patients illustrates that NNMT protein is predominantly expressed in the cancer stroma at varying levels, and about 20% of cancer tissues overexpress NNMT when compared to levels observed in normal colorectal mucosa. Clinical correlation analyses of 572 patients with early-stage cancers reveal that NNMT protein overexpression is significantly associated with shorter overall and disease-free survival, but no such correlation is found in late-stage colorectal cancer. Analyses of TCGA and CPTAC colorectal cancer cohorts show that NNMT mRNA expression is positively correlated with protein levels, is significantly higher in CIMP-high or MSI subtypes than in CIMP-low or MSS subtypes, and is positively correlated with its paralog INMT but not with its interaction partners such as PNMT, ADK, APP, ATF6, BMF, BRD4, CDC37, or CRYZ. In early-stage cancers, NNMT expression is higher in BRAF-mutated than in BRAF wild type tumors but is not affected by KRAS or PIK3CA mutation status. As a cancer stromal protein with important roles in metabolism and cancer epigenetics, NNMT is emerging as a promising biomarker for risk stratification of early-stage cancers.

Prognostic value of nicotinamide N-methyltransferase in human cancers: Evidence from a meta-analysis and database validation

Background

Previous studies indicated that dysregulated expression of nicotinamide N-methyltransferase (NNMT) contributed to the tumor progression and predicted poor prognosis in various cancers. However, there was no exact conclusion on account of the contradictory results across studies.

Methods

The relevant studies up to December 7, 2020 were searched in PubMed, Web of Science, and Embase. The association between NNMT expression and prognostic outcomes was explored, including overall survival (OS), disease-free survival (DFS), and clinicopathological features. The bioinformatics database was used to validate the findings.

Results

Thirteen retrospective studies containing 2,591 patients with cancers were included in this analysis. High NNMT expression was significantly associated with shorter OS (hazard ratio [HR] = 2.01, 95% confidence interval [CI] = 1.42–2.86, and P < 0.01) and DFS (HR = 1.59, 95% CI = 1.23–2.05, and P < 0.01) compared to low NNMT expression in cancers. Compared to patients with low NNMT expression, patients with high NNMT expression tended to have worse tumor differentiation (P = 0.03), earlier lymph node metastasis (P = 0.01), earlier distant metastasis (P = 0.02), and more advanced clinical stage (P < 0.01).

Conclusion

High NNMT expression is an unfavorable factor of various cancers. NNMT is a promising indicator to predict the prognosis of various cancers and can serve as a potential therapeutic target in various cancers.

Nicotinamide N-Methyltransferase in Head and Neck Tumors: A Comprehensive Review

The head and neck tumors (HNT) are a heterogeneous group of diseases ranging from benign to malignant lesions, with distinctive molecular and clinical behaviors. Several studies have highlighted the presence of an altered metabolic phenotype in HNT, such as the upregulation of nicotinamide N-methyltransferase (NNMT). However, its biological effects have not been completely disclosed and the role of NNMT in cancer cell metabolism remains unclear. Therefore, this comprehensive review aims to evaluate the available literature regarding the biological, diagnostic, and prognostic role of NNMT in HNT. NNMT was shown to be significantly overexpressed in all of the evaluated HNT types. Moreover, its upregulation has been correlated with cancer cell migration and adverse clinical outcomes, such as high-pathological stage, lymph node metastasis, and locoregional recurrences. However, in oral squamous cell carcinoma (OSCC) these associations are still debated, and several studies have failed to demonstrate the prognostic significance of NNMT. The shRNA-mediated gene silencing efficiently suppressed the NNMT gene expression and exhibited a clear inhibitory effect on cell proliferation, promoting the expression of apoptosis-related proteins and modulating the cell cycle. NNMT could represent a new molecular biomarker and a new target of molecular-based therapy, although further studies on larger patient cohorts are needed to explore its biological role in HNT.

Methylosystem for Cancer Sieging Strategy

As cancer is a genetic disease, methylation defines a biologically malignant phenotype of cancer in the association of one-carbon metabolism-dependent S-adenosylmethionine (SAM) as a methyl donor in each cell. Methylated substances are involved in intracellular metabolism, but via intercellular communication, some of these can also be secreted to affect other substances. Although metabolic analysis at the single-cell level remains challenging, studying the "methylosystem" (i.e., the intercellular and intracellular communications of upstream regulatory factors and/or downstream effectors that affect the epigenetic mechanism involving the transfer of a methyl group from SAM onto the specific positions of nucleotides or other metabolites in the tumor microenvironment) and tracking these metabolic products are important research tasks for understanding spatial heterogeneity. Here, we discuss and highlight the involvement of RNA and nicotinamide, recently emerged targets, in SAM-producing one-carbon metabolism in cancer cells, cancer-associated fibroblasts, and immune cells. Their significance and implications will contribute to the discovery of efficient methods for the diagnosis of and therapeutic approaches to human cancer.

The Utility of Nicotinamide N-Methyltransferase as a Potential Biomarker to Predict the Oncological Outcomes for Urological Cancers: An Update

Nicotinamide N-methyltransferase (NNMT) catalyzes the N-methylation reaction of nicotinamide, using S-adenosyl-L-methionine as the methyl donor. Enzyme overexpression has been described in many non-neoplastic diseases, as well as in a wide range of solid malignancies. This review aims to report and discuss evidence available in scientific literature, dealing with NNMT expression and the potential involvement in main urologic neoplasms, namely, renal, bladder and prostate cancers. Data illustrated in the cited studies clearly demonstrated NNMT upregulation (pathological vs. normal tissue) in association with these aforementioned tumors. In addition to this, enzyme levels were also found to correlate with key prognostic parameters and patient survival. Interestingly, NNMT overexpression also emerged in peripheral body fluids, such as blood and urine, thus leading to candidate the enzyme as promising biomarker for the early and non-invasive detection of these cancers. Examined results undoubtedly showed NNMT as having the capacity to promote cell proliferation, migration and invasiveness, as well as its potential participation in fundamental events highlighting cancer progression, metastasis and resistance to chemo- and radiotherapy. In the light of this evidence, it is reasonable to attribute to NNMT a promising role as a potential biomarker for the diagnosis and prognosis of urologic neoplasms, as well as a molecular target for effective anti-cancer treatment.

Nicotinamide N-methyltransferase decreases 5-fluorouracil sensitivity in human esophageal squamous cell carcinoma through metabolic reprogramming and promoting the Warburg effect

Esophageal squamous cell carcinoma (ESCC) is a common malignant tumor with poor prognosis. And different individuals respond to the same drug differently. Increasing evidence has confirmed that metabolism reprogramming was involved in the drug sensitivity of tumor cells. However, the potential molecular mechanism of 5-fluorouracil (5-FU) sensitivity remains to be elucidated in ESCC cells. In this study, we found that the 5-FU sensitivity of TE1 cells was lower than that of EC1 and Eca109 cells. Gas chromatography-mass spectrometry analysis results showed that nicotinate and nicotinamide metabolism and tricarboxylic acid cycle were significantly different in these three cell lines. Nicotinamide N-methyltransferase (NNMT), a key enzyme of nicotinate and nicotinamide metabolism, was significantly higher expressed in TE1 cells than that in EC1 and Eca109 cells. Therefore, the function of NNMT on 5-FU sensitivity was analyzed in vitro and in vivo. NNMT downregulation significantly increased 5-FU sensitivity in TE1 cells. Meanwhile, the glucose consumption and lactate production were decreased, and the expression of glycolysis-related enzymes hexokinase 2, lactate dehydrogenase A, and phosphoglycerate mutase 1 were downregulated in NNMT knockdown TE1 cells. Besides, overexpression of NNMT in EC1 and Eca109 cells caused the opposite effects. Moreover, when glycolysis was inhibited by 2-deoxyglucose, the roles of NNMT on 5-FU sensitivity was weakened. In vivo experiments showed that NNMT knockdown significantly increased the sensitivity of xenografts to 5-FU and suppressed the Warburg effect. Overall, these results demonstrated that NNMT decreases 5-FU sensitivity in human ESCC cells through promoting the Warburg effect, suggesting that NNMT may contribute to predict the treatment effects of the clinical chemotherapy in ESCC.

Nicotinamide N-methyltransferase in nonmelanoma skin cancers

BACKGROUND

Squamous cell carcinoma (SCC) and basal cell carcinoma (BCC) represent the most common forms of nonmelanoma skin cancers (NMSCs). Although successful treatment of these neoplasms is based on surgical excision, an increasing number of BCCs relapses and many SCCs display high rates of recurrence and metastasis. Nicotinamide N-methyltransferase (NNMT) is a cytosolic enzyme, which was found to be upregulated in different solid tumours. However, there are no data regarding enzyme expression in NMSCs. The aim of this study was therefore to evaluate the potential involvement of NNMT in BCCs and SCCs.

MATERIALS AND METHODS

Immunohistochemical analyses were carried out on 40 BCC cases and 39 SCC cases, to evaluate enzyme expression in tumour and surrounding healthy margins. Moreover, the relationship between NNMT intratumour levels and clinico-pathological parameters were explored.

RESULTS

Nicotinamide N-methyltransferase was found to be overexpressed in BCCs compared with control tissues, while a significant enzyme downregulation was detected in SCCs with respect to corresponding healthy margins. In addition, NNMT levels were negatively related to aggressiveness of both BCCs (distinguishing between infiltrative and nodular tumours) and SCCs (considering head and neck forms and tumours of the extremities and trunk).

CONCLUSIONS

These evidences seem to demonstrate that the different NNMT dysregulation detected in BCC and SCC may be the result of important biological traits distinctively characterizing these two forms within NMSCs. In addition, enzyme levels seem to be inversely correlated with tumour aggressiveness, thus suggesting the potential suitability of the enzyme as a prognostic biomarker for both neoplasms.

Transcriptome profiling reveals PDZ binding kinase as a novel biomarker in peritumoral brain zone of glioblastoma

PURPOSE

Peritumoural brain zone (PT) of glioblastoma (GBM) is the area where tumour recurrence is often observed. We aimed to identify differentially regulated genes between tumour core (TC) and PT to understand the underlying molecular characteristics of infiltrating tumour cells in PT.

METHODS

17 each histologically characterised TC and PT tissues of GBM along with eight control tissues were subjected to cDNA Microarray. PT tissues contained 25-30% infiltrating tumour cells. Data was analysed using R Bioconductor software. Shortlisted genes were validated using qRT-PCR. Expression of one selected candidate gene, PDZ Binding Kinase (PBK) was correlated with patient survival, tumour recurrence and functionally characterized in vitro using gene knock-down approach.

RESULTS

Unsupervised hierarchical clustering showed that TC and PT have distinct gene expression profiles compared to controls. Further, comparing TC with PT, we observed a significant overlap in gene expression profile in both, despite PT having fewer infiltrating tumour cells. qRT-PCR for 13 selected genes validated the microarray data. Expression of PBK was higher in PT as compared to TC and recurrent when compared to newly diagnosed GBM tumours. PBK knock-down showed a significant reduction in cell proliferation, migration and invasion with increase in sensitivity to radiation and Temozolomide treatment.

CONCLUSIONS

We show that several genes of TC are expressed even in PT contributing to the vulnerability of PT for tumour recurrence. PBK is identified as a novel gene up-regulated in PT of GBM with a strong role in conferring aggressiveness, including radio-chemoresistance, thus contributing to recurrence in GBM tumours.

Prognostic Value of Nicotinamide N-Methyltransferase Expression in Patients With Solid Tumors: A Systematic Review and Meta-Analysis

Background: Nicotinamide N-methyltransferase (NNMT) is an enzyme that catalyzes N-methylation of pyridine-containing compounds. NNMT is upregulated in many types of solid tumors, suggesting the potential for its use as a tumor biomarker. However, the prognostic value of NNMT in solid tumors is still unclear. We therefore conducted a meta-analysis to investigate the association between NNMT expression and survival in patients with solid tumors.

Methods: We focused on patients with solid tumors, using high NNMT expression levels as the intervention and low NNMT expression levels as the comparison, according to Patient, Intervention, Comparison, and Outcome (PICO) guidelines. Electronic databases (up to June 7, 2018) were comprehensively searched to collect relevant cohort studies regarding the associations between NNMT expression levels and survival outcomes (overall survival [OS], disease-specific survival [DSS] including cancer-specific survival [CSS], and time to tumor progression [TTP] including disease-free survival [DFS], progression-free survival [PFS], and metastasis-free survival [MeFS]). Publication biases were also examined. All analyses were performed using STATA 12.0 software.

Results: A total of 3340 patients with solid tumors from nine published studies were included. The combined hazard ratio (HR) identified high NNMT expression levels as a poor prognostic predictor of OS (HR = 1.67, 95% CI = 1.23–2.26). However, NNMT levels had no significant association with DSS (HR = 1.47, 95% CI = 0.95–2.28) and TTP (HR = 1.13, 95%CI = 0.39–3.25).

Conclusion: High NNMT expression levels may be a poor prognostic biomarker for patients with solid tumors.

Inhibition of Prostate Cancer DU-145 Cells Proliferation by Anthopleura anjunae Oligopeptide (YVPGP) via PI3K/AKT/mTOR Signaling Pathway

We investigated the antitumor mechanism of Anthopleura anjunae oligopeptide (AAP-H, YVPGP) in prostate cancer DU-145 cells in vitro and in vivo. Results indicated that AAP-H was nontoxic and exhibited antitumor activities. Cell cycle analysis indicated that AAP-H may arrest DU-145 cells in the S phase. The role of the phosphatidylinositol 3-kinase/protein kinase B/mammalian rapamycin target protein (PI3K/AKT/mTOR) signaling pathway in the antitumor mechanism of APP-H was investigated. Results showed that AAP-H treatment led to dose-dependent reduction in the levels of p-AKT (Ser473), p-PI3K (p85), and p-mTOR (Ser2448), whereas t-AKT and t-PI3K levels remained unaltered compared to the untreated DU-145 cells. Inhibition of PI3K/AKT/mTOR signaling pathway in the DU-145 cells by employing inhibitor LY294002 (10 μM) or rapamycin (20 nM) effectively attenuated AAP-H-induced phosphorylation of AKT and mTOR. At the same time, inhibitor addition further elevated AAP-H-induced cleaved-caspase-3 levels. Furthermore, the effect of AAP-H on tumor growth and the role of the PI3K/AKT/mTOR signaling pathway in nude mouse model were also investigated. Immunohistochemical analysis showed that activated AKT, PI3K, and mTOR levels were reduced in DU-145 xenografts. Western blotting showed that AAP-H treatment resulted in dose-dependent reduction in p-AKT (Ser473), p-PI3K (p85), and p-mTOR (Ser2448) levels, whereas t-AKT and t-PI3K levels remained unaltered. Similarly, Bcl-xL levels decreased, whereas that of Bax increased after AAP-H treatment. AAP-H also increased initiator (caspase 8 and 9) and executor caspase (caspase 3 and 7) levels. Therefore, the antitumor mechanism of APP-H on DU-145 cells may involve regulation of the PI3K/AKT/mTOR signaling pathway, which eventually promotes apoptosis via mitochondrial and death receptor pathways. Thus, the hydrophobic oligopeptide (YVPGP) can be developed as an adjuvant for the prevention or treatment of prostate cancer in the future.

Nicotinamide N-methyltransferase enhances the progression of prostate cancer by stabilizing sirtuin 1

A previous study demonstrated that nicotinamide N-methyltransferase (NNMT) is upregulated in the tissues of patients with prostate cancer (PCa); however, the specific underlying mechanism of this remains unclear. To begin with, the expression of NNMT was investigated in the peripheral blood of patients with PCa and of healthy control subjects. The results indicated that the expression level of NNMT was elevated in the peripheral blood and tissues of patients with PCa. Furthermore, the overexpression of NNMT enhanced PC-3 cell viability, invasion and migration capacity. Additionally, the overexpression of NNMT significantly increased the mRNA level of sirtuin 1 (SIRT1) in PC-3 cells. In addition, nicotinamide treatment significantly suppressed the expression of SIRT1 even in PC-3 cells transfected with adeno-associated virus-NNMT. Furthermore, the PC-3 cell invasion capacity was notably decreased by the nicotinamide treatment; however, such effects were largely abolished by the overexpression of NNMT in PC-3 cells. These data indicated that NNMT enhanced PC-3 cell migration and invasion mainly by regulating SIRT1 expression. In summary, the present study indicated that NNMT is an important regulator of SIRT1 expression in PC-3 cells and may be a potential therapeutic target for PCa.

Covalent inhibitors of nicotinamide N-methyltransferase (NNMT) provide evidence for target engagement challenges in situ

Nicotinamide N-methyltransferase (NNMT) catalyzes the N-methylation of nicotinamide using S-adenosyl-L-methionine (SAM) as a methyl donor and, through doing so, can modulate cellular methylation potential to impact diverse epigenetic processes. NNMT has been implicated in a range of diseases, including cancer and metabolic disorders. Potent, selective, and cell-active inhibitors would constitute valuable probes to study the biological functions and therapeutic potential of NNMT. We previously reported the discovery of electrophilic small molecules that inhibit NNMT by reacting with an active-site cysteine residue in the SAM-binding pocket. Here, we have used activity-based protein profiling (ABPP)-guided medicinal chemistry to optimize the potency and selectivity of NNMT inhibitors, culminating in the discovery of multiple alpha-chloroacetamide (αCA) compounds with sub-µM IC₅₀ values in vitro and excellent proteomic selectivity in cell lysates. However, these compounds showed much weaker inhibition of NNMT in cells, a feature that was not shared by off-targets of the αCAs. Our results show the potential for developing potent and selective covalent inhibitors of NNMT, but also highlight challenges that may be faced in targeting this enzyme in cellular systems.

Nicotinamide N-methyltransferase: potential involvement in cutaneous malignant melanoma

Nicotinamide N-methyltransferase (NNMT) is an enzyme that catalyzes the N-methylation of nicotinamide and pyridine compounds, participating in xenobiotic and drug metabolism. Data on literature have evidenced a possible role of NNMT in many solid cancers, but no data are currently available in cutaneous melanoma. Recent important advances have been achieved in the treatment of advanced melanoma with targeted therapy and immunotherapy. However, the identification of biomarkers that can be used for the detection of early stage disease as well as for monitoring the therapeutic response during treatment is of utmost importance. The aim of this study was to study the possible role of NNMT in melanoma. In the present study, we carried out immunohistochemical analyses to evaluate the expression of the enzyme NNMT in 34 melanomas and 34 nevi. Moreover, we explored the relationship between NNMT levels and the prognostic parameters of patients with melanoma. The results obtained showed significantly (P<0.0001) higher NNMT expression in melanoma compared with that detected in nevi. In addition, a significant (P<0.05) inverse relationship was found between enzyme levels and Breslow thickness, Clark level, the presence/number of mitoses, and ulceration. Taken together, these data seem to suggest that NNMT could represent a molecular biomarker for melanoma, thus highlighting its potential for both diagnosis and prognosis of this neoplasm.

Glutaredoxin 3 promotes nasopharyngeal carcinoma growth and metastasis via EGFR/Akt pathway and independent of ROS

Glutaredoxin 3 (GLRX3) is antioxidant enzyme, maintaining a low level of ROS, thus contributing to the survival and metastasis of several types of cancer. However, the expression and functions of GLRX3 have not been addressed in nasopharyngeal carcinoma (NPC). In this study, we found that GLRX3 was overexpressed in NPC. Knockdown of GLRX3 in NPC cell lines inhibited proliferation in vitro, tumorignesis in vivo, and colony formation. In addition, GLRX3 knockdown decreased the migration and invasion capacity of NPC cells by reversing the epithelial-mesenchymal transition (EMT). Furthermore, stabilization of GLRX3 was positively related to with epidermal growth factor receptor (EGFR) expression and negatively with ROS generation. Phosphorylation of Akt, a key downstream effector, was induced by EGFR signaling but did not rely on increasing ROS level in NPC cells. GLRX3 might be an oncoprotein in NPC, playing important roles in increasing redox reaction and activating EGFR/ Akt signals, so it may be a therapeutic target for NPC.

Nicotinamide N-Methyltransferase in Health and Cancer

Over the past decade, the roles of nicotinamide N-methyltransferase and its product 1-methyl nicotinamide have emerged from playing merely minor roles in phase 2 xenobiotic metabolism as actors in some of the most important scenes of human life. In this review, the structures of the gene, messenger RNA, and protein are discussed, together with the role of the enzyme in many of the common cancers that afflict people today.

HOXC6 Overexpression Is Associated With Ki-67 Expression and Poor Survival in NPC Patients

BACKGROUND: Homeobox (HOX) genes are expressed in adult cells and regulate expression of genes involved in cell proliferation as well as cell-cell and cell-extracellular matrix interactions. Dysregulation of HOX gene expression plays important roles in carcinogenesis in a variety of organs. Through data mining on a published transcriptome dataset, this study first identified Homeobox protein Hox-C6 (HOXC6) gene as one of the differentially upregulated genes in nasopharyngeal carcinoma (NPC). We aimed to evaluate HOXC6 expression and its prognostic effect in a large cohort of NPC patients.

METHODS: We retrospectively examined the HOXC6 expression and Ki-67 index by immunohistochemistry in biopsy specimens from 124 patients with non-metastasized NPC. The results were correlated with the clinicopathological variables including disease-specific survival (DSS), metastasis-free survival (MeFS), and local recurrence-free survival (LRFS).

RESULTS: HOXC6 high expression was positively correlated with increased Ki-67 labeling index, and significantly associated with increment of tumor stage (p=0.024), advanced nodal status (p<0.001) and American Joint Committee on Cancer (AJCC) stage (p=0.002). Its expression also correlated with worse prognosis in terms of DSS (p=0.008), MeFS (p=0.0047) univariately. In multivariate analyses, HOXC6 expression still remained prognostically independent to portend worse DSS (p=0.015, hazard ratio=1.988) and MeFS (p=0.036, hazard ratio=1.899), together with stage III-IV (p=0.024, DSS; p=0.043, MeFS).

CONCLUSION: In summary, our results suggest HOXC6 may play a critical role in NPC progression and may serve as a potential prognostic biomarker in NPC patients.

Identification of specific biomarkers for gastric adenocarcinoma by ITRAQ proteomic approach

The aim of this study was to identify biomarkers for gastric cancer (GC) by iTRAQ. Using proteins extracted from a panel of 4 pairs of gastric adenocarcinoma samples (stage III-IV, Her-2 negative), we identified 10 up regulated and 9 down regulated proteins in all four pairs of GC samples compared to adjacent normal gastric tissue. The up regulated proteins are mainly involved in cell motility, while the down regulated proteins are mitochondrial enzymes involved in energy metabolism. The expression of three up regulated proteins (ANXA1, NNMT, fibulin-5) and one of the down regulated proteins (UQCRC1) was validated by Western Blot in 97 GC samples. ANXA1 was up regulated in 61.36% of stage I/II GC samples compared to matched adjacent normal gastric tissue, and its expression increased further in stage III/IV samples. Knockdown of ANXA1 by siRNA significantly inhibited GC cell migration and invasion, whereas over expression of ANXA1 promoted migration and invasion. We found decreased expression of UQCRC1 in all stages of GC samples. Our data suggest that increased cell motility and decreased mitochondrial energy metabolism are important hallmarks during the development of GC.

Characterization and Prognostic Significance of Methylthioadenosine Phosphorylase Deficiency in Nasopharyngeal Carcinoma

Identification of cancer-associated genes by genomic profiling contributes to the elucidation of tumor development and progression. The methylthioadenosine phosphorylase (MTAP) gene, located at chromosome 9p21, plays a critical role in tumorigenicity and disease progression in a wide variety of cancers. However, the prognostic impact of MTAP in patients with nasopharyngeal carcinoma (NPC) remains obscured. Through data mining from published transcriptomic database, MTAP was first identified as a differentially downregulated gene in NPC. In this study, our aim was to evaluate the expression of MTAP in NPC and to clarify its prognostic significance.MTAP immunohistochemistry was retrospectively performed and analyzed in biopsy specimens from 124 NPC patients who received standard treatment without distant metastasis at initial diagnosis. The immunoexpression status was correlated with the clinicopathological variables, disease-specific survival (DSS), distant metastasis-free survival (DMFS), and local recurrence-free survival (LRFS). Real-time quantitative polymerase chain reaction (PCR) was used to measure MTAP gene dosage. In some cases, we also performed methylation-specific PCR and pyrosequencing to assess the status of promoter methylation.MTAP deficiency was significantly associated with advanced tumor stages (P = 0.023) and univariately predictive of adverse outcomes for DSS, DMFS, and LRFS. In the multivariate comparison, MTAP deficiency still remained prognostically independent to portend worse DSS (P = 0.021, hazard ratio = 1.870) and DMFS (P = 0.009, hazard ratio = 2.154), together with advanced AJCC stages III to IV. Homozygous deletion or promoter methylation of MTAP gene were identified to be significantly associated with MTAP protein deficiency (P < 0.001).MTAP deficiency was correlated with an aggressive phenotype and independently predictive of worse DSS and DMFS, suggesting its role in disease progression and as an independent prognostic biomarker of NPC, which potentially offers new strategy of targeted treatment for patients lacking MTAP expression.

Prognostic significance of the EGFR pathway in nasopharyngeal carcinoma: a systematic review and meta-analysis

OBJECTIVE

To evaluate the prognostic impact of the EGF receptor (EGFR) pathway molecules and assess their clinical usefulness.

METHODS

We conducted a systematic review. Pubmed and EMBASE were searched January 2014. The prognostic relevance of EGFR, JAK, PI3K, PIK3CA, STAT3, STAT5, PTEN, AKT, mTOR, GRB2, SOS, RAF, RAS, MAPK, ERK, MEK and CCND1 in nasopharyngeal carcinoma was assessed. The outcomes considered were overall survival, disease-free survival and tumor-node-metastasis stage. Twenty-two studies were included. Risk of bias was evaluated. Meta-analysis for which pooled hazard ratios and 95% CIs were calculated.

CONCLUSION

EGFR overexpression predicts a worse overall survival and disease-free survival in nasopharyngeal carcinoma, but no specific causal pathway molecule could be identified.

Effects of radiotherapy on nasopharyngeal carcinoma cell invasiveness

Radiotherapy is widely used in the treatment of nasopharyngeal carcinoma (NPC), whereas its effects on the NPC growth, survival, and metastases have not been completely evaluated. Here, we compared the detected metastatic NPC tissues after radiotherapy (m-NPC) to the resected primary NPC tissues prior to radiotherapy (p-NPC). We detected higher levels of Snail2 protein, but not mRNA in m-NPC, compared to p-NPC. In vitro, a modest irradiation on NPC cells resulted in significant cell death, but increased Snail2 protein, but mRNA levels in the surviving NPC cells. Bioinformatics analyses showed that miR-613, which was significantly decreased in NPC cells after irradiation, targeted the 3'-UTR of Snail2 mRNA to inhibit its translation. Moreover, miR-613 overexpression inhibited Snail2-mediated cell invasiveness, while miR-613 depletion increased Snail2-mediated cell invasiveness in NPC cells. Finally, we detected significantly lower levels of miR-613 in m-NPC, compared to p-NPC. Together our data suggest that although radiotherapy induced NPC cell death, it may increase Snail2-mediated NPC cell invasiveness through downregulating miR-613.

AMACR overexpression as a poor prognostic factor in patients with nasopharyngeal carcinoma

The molecular prognostic adjunct in patients with nasopharyngeal carcinomas (NPCs) still remains obscured. Through data mining from published transcriptomic database, alpha-methylacyl-CoA racemase (AMACR) was first identified as a differentially upregulated gene in NPC tissues, which is a key enzyme for isometric conversion of fatty acids entering the β-oxidation. Given the roles of AMACR in prognostication and frontline therapeutic regimen of common carcinomas, such as prostate cancer, we explored AMACR immunoexpression status and its clinical significance in NPC patients. AMACR immunohistochemistry was retrospectively performed and analyzed using H-score for biopsy specimens from 124 NPC patients who received standard treatment without distant metastasis at initial diagnosis. Those cases with H-score larger than the median value were construed as featuring AMACR overexpression. The findings were correlated with the clinicopathological variables, disease-specific survival (DSS), distant metastasis-free survival (DMFS), and local recurrence-free survival (LRFS). Endogenous AMACR protein expressions were assessed by real-time reverse-transcription polymerase chain reaction (RT-PCR) and Western blotting in NPC cells and non-neoplastic mucosal cells. AMACR overexpression was significantly associated with increment of primary tumor status (P = 0.009) and univariately predictive of adverse outcomes for DSS, DMFS, and LRFS. In the multivariate comparison, AMACR overexpression still remained prognostically independent to portend worse DSS (P = 0.006, hazard ratio = 2.129), DMFS (P = 0.001, hazard ratio = 2.795), and LRFS (P = 0.041, hazard ratio = 2.009), together with advanced American Joint of Cancer Committee (AJCC) stages III-IV. Compared with non-neoplastic cells, both HONE1 and TW01 NPC cells demonstrated markedly increased AMACR expression. AMACR overexpression was identified as an important prognosticator and a potential therapeutic target in the future.

Galectin-1 overexpression in nasopharyngeal carcinoma: effect on survival

CONCLUSIONS

Galectin-1 overexpression is significantly correlated with the survival rate of patients with nasopharyngeal carcinoma (NPC). Immunohistochemical analysis of galectin-1 expression might be useful for identifying patients with a high risk of distant metastasis and for prompting timely adjuvant systemic therapy for patients with aggressive NPC.

OBJECTIVES

We examined the effect of galectin-1 on the survival rate of patients with NPC.

METHODS

A total of 124 patients diagnosed between 1998 and 2002 with NPC without distant metastasis were enrolled in this single-center historical prospective cohort study. Immunohistochemical analysis was used to correlate the galectin-1 expression score in the cytoplasm and the survival rate of patients with NPC.

RESULTS

Patients with NPC who overexpressed galectin-1 in cytoplasm showed more aggressive tumor growth and significantly shorter disease-specific survival (DSS) (p = 0.0037) and distant metastasis-free survival (DMFS) (p = 0.0006) than patients with NPC who did not overexpress galectin-1. Multivariate analysis showed that galectin-1 overexpression remained prognostically independent for DSS (p = 0.031, hazard ratio = 1.821), and DMFS (p = 0.005, hazard ratio = 2.417), together with the advanced III-IV stages.

Cyclin-dependent kinase 4 overexpression is mostly independent of gene amplification and constitutes an independent prognosticator for nasopharyngeal carcinoma

Data mining in the public domain demonstrates that cyclin-dependent kinase 4 (CDK4) is highly expressed in nasopharyngeal carcinomas (NPC). Associated with cyclin-D, CDK4 phosphorylates and inactivates retinoblastoma (Rb) protein family members and mediates progression through the G1- to the S-phase of the cell cycle. Amplification and overexpression of CDK4 has been identified in various human malignancies. However, its expression and amplification has never been systemically evaluated in NPC. This study aimed to evaluate the amplification and expression status, correlation with clinicopathological features, and prognostic implications of CDK4 based on public domain dataset and in our well-defined cohort of NPC patients. The association between CDK4 transcript level and gene dosage was explored by analysis of an independent public domain dataset. We retrospectively assessed CDK4 immunoexpression in biopsies of 124 consecutive NPC patients devoid of initial distant metastasis and treated according to consistent guidelines. The results were correlated with clinicopathological features, local recurrence-free survival (LRFS), distant metastasis-free survival (DMeFS), and disease-specific survival (DSS). High levels of CDK4 protein were positively correlated with the T 3, 4 status (p = 0.024); N 2, 3 status (p < 0.001); and the American Joint Committee on Cancer stage 3, 4 (p < 0.001). Multivariate analysis suggested high CDK4 expression was an independent prognostic indicator of worse DMeFS (p = 0.001, hazard ratio (HR) = 3.226) and DSS (p = 0.037, HR = 1.838). Although CDK4 is frequently upregulated, its gene locus is very uncommonly amplified in NPC. CDK4 overexpression is mostly independent with gene amplification and represents a potential prognostic biomarker in NPC and may indicate tumor aggressiveness through cell cycle dysregulation.

Down-regulation of nicotinamide N-methyltransferase induces apoptosis in human breast cancer cells via the mitochondria-mediated pathway

Nicotinamide N-methyltransferase (NNMT) has been found involved in cell proliferation of several malignancies. However, the functional role of NNMT in breast cancer has not been elucidated. In the present study, we showed that NNMT was selectively expressed in some breast cancer cell lines, down-regulation of NNMT expression in Bcap-37 and MDA-MB-231 cell lines by NNMT shRNA significantly inhibited cell growth in vitro, decreased tumorigenicity in mice and induced apoptosis. The silencing reciprocal effect of NNMT was confirmed by over-expressing NNMT in the MCF-7 and SK-BR-3 breast cancer cell lines which lack constitutive expression of NNMT. In addition, down-regulation of NNMT expression resulted in reducing expression of Bcl-2 and Bcl-xL, up-regulation of Bax, Puma, cleaved caspase-9, cleaved caspase-3 and cleaved PARP, increasing reactive oxygen species production and release of cytochrome c from mitochondria, and decreasing the phosphorylation of Akt and ERK1/2. These data suggest that down-regulation of NNMT induces apoptosis via the mitochondria-mediated pathway in breast cancer cells.

Fibronectin overexpression is associated with latent membrane protein 1 expression and has independent prognostic value for nasopharyngeal carcinoma

Despite recent improvements in the diagnosis and treatment, the final outcomes in patients with nasopharyngeal carcinomas (NPC) still remain suboptimal. Through data mining from published transcriptomic database with further bioinformatic validation, fibronectin (FN1) was identified as a differentially upregulated gene in NPC tissues, which implicates the transition from epithelial to mesenchymal phenotype (EMT) and promotes metastasis. Given the roles of fibronectin in risk stratification and in the frontline therapeutics of common carcinomas, such as renal cell cancer, we explored fibronectin immunoexpression status and its associations with clinicopathological variables and survival in a well-defined cohort of NPC patients. Fibronectin immunohistochemistry was retrospectively performed and analyzed using H-score for 124 biopsy specimens from NPC patients who received standard treatment without distant metastasis at initial diagnosis. Those cases with H-score higher than the median value were regarded as fibronectin overexpression. The findings were correlated with clinicopathological variables, EBV latent membrane protein 1 (LMP1) expression, disease-specific survival (DSS), distant metastasis-free survival (DMFS), and local recurrence-free survival (LRFS). Fibronectin overexpression was significantly associated with American Joint Committee on Cancer (AJCC) stages III-IV (p = 0.019) and LMP1 expression (p = 0.004), and univariately predictive of adverse outcomes for DSS, DMFS, and LRFS (all p < 0.0001). In the multivariate comparison, fibronectin overexpression still remained prognostically independent to portend worse DSS (p < 0.01, hazard ratio = 5.958), DMFS (p < 0.01, hazard ratio = 5.728), and LRFS (p < 0.01, hazard ratio = 5.411) together with a vanced AJCC stages III-IV. Fibronectin is upregulated in a subset of NPCs, and its increased immunoexpression significantly correlated with advanced features, justifying the potentiality of fibronectin as a theragnostic biomaker of NPC.