nm23-H1 expression and loss of heterozygosity in colon adenocarcinoma

Identification and validation of smoking-related genes in lung adenocarcinoma using an in vitro carcinogenesis model and bioinformatics analysis

Background

Lung cancer is one of the most common carcinomas in the world, and lung adenocarcinoma (LUAD) is the most lethal and most common subtype of lung cancer. Cigarette smoking is the most leading risk factor of lung cancer, but it is still unclear how normal lung cells become cancerous in cigarette smokers. This study aims to identify potential smoking-related biomarkers associated with the progression and prognosis of LUAD, as well as their regulation mechanism using an in vitro carcinogenesis model and bioinformatics analysis.

Results

Based on the integration analysis of four Gene Expression Omnibus (GEO) datasets and our mRNA sequencing analysis, 2 up-regulated and 11 down-regulated genes were identified in both S30 cells and LUAD. By analyzing the LUAD dataset in The Cancer Gene Analysis (TCGA) database, 3 of the 13 genes, viz., glycophorin C (GYPC), NME/NM23 nucleoside diphosphate kinase 1 (NME1) and slit guidance ligand 2 (SLIT2), were found to be significantly correlated with LUAD patients’ smoking history. The expression levels of GYPC, NME1 and SLIT2 in S30 cells and lung cancer cell lines were validated by quantitative PCR, immunofluorescence, and western blot assays. Besides, these three genes are associated with tumor invasion depth, and elevated expression of NME1 was correlated with lymph node metastasis. The enrichment analysis suggested that these genes were highly correlated to tumorigenesis and metastasis-related biological processes and pathways. Moreover, the increased expression levels of GYPC and SLIT2, as well as decreased expression of NME1 were associated with a favorable prognosis in LUAD patients. Furthermore, based on the multi-omics data in the TCGA database, these genes were found to be regulated by DNA methylation.

Conclusion

In conclusion, our observations indicated that the differential expression of GYPC, NME1 and SLIT2 may be regulated by DNA methylation, and they are associated with cigarette smoke-induced LUAD, as well as serve as prognostic factors in LUAD patients.

The Function of NM23-H1/NME1 and Its Homologs in Major Processes Linked to Metastasis

Metastasis suppressor genes (MSGs) inhibit different biological processes during metastatic progression without globally influencing development of the primary tumor. The first MSG, NM23 (non-metastatic clone 23, isoform H1) or now called NME1 (stands for non-metastatic) was identified some decades ago. Since then, ten human NM23 paralogs forming two groups have been discovered. Group I NM23 genes encode enzymes with evolutionarily highly conserved nucleoside diphosphate kinase (NDPK) activity. In this review we summarize how results from NDPKs in model organisms converged on human NM23 studies. Next, we examine the role of NM23-H1 and its homologs within the metastatic cascade, e.g. cell migration and invasion, proliferation and apoptosis. NM23-H1 homologs are well known inhibitors of cell migration. Drosophila studies revealed that AWD, the fly counterpart of NM23-H1 is a negative regulator of cell motility by modulating endocytosis of chemotactic receptors on the surface of migrating cells in cooperation with Shibire/Dynamin; this mechanism has been recently confirmed by human studies. NM23-H1 inhibits proliferation of tumor cells by phosphorylating the MAPK scaffold, kinase suppressor of Ras (KSR), resulting in suppression of MAPK signalling. This mechanism was also observed with the C. elegans homolog, NDK-1, albeit with an inverse effect on MAPK activation. Both NM23-H1 and NDK-1 promote apoptotic cell death. In addition, NDK-1, NM23-H1 and their mouse counterpart NM23-M1 were shown to promote phagocytosis in an evolutionarily conserved manner. In summary, inhibition of cell migration and proliferation, alongside actions in apoptosis and phagocytosis are all mechanisms through which NM23-H1 acts against metastatic progression.

Clinical Implication and the Hereditary Factors of NM23 in Hepatocellular Carcinoma Based on Bioinformatics Analysis and Genome-Wide Association Study

NM23 expression is closely associated with hepatocellular carcinoma (HCC) recurrence, but the hereditary factors influencing NM23 levels are unknown. Using public database, the diagnostic value of NM23 in HCC was investigated. A total of 424 hepatitis B virus- (HBV-) related HCC patients were enrolled to perform a genome–wide association study for identifying candidate variants associated with NM23 expression level. Additionally, a logistic regression model, haplotypes, and survival analysis were performed in the subsequent analysis. We identified high NM23 expression levels that have a diagnostic accuracy in HCC tissues and had a poor recurrence-free survival in HBV-related HCC patients. Variants near Psoriasis susceptibility 1 candidate 1 (PSORS1C1) and StAR related lipid transdomain containing 3 (STARD3) are associated with NM23 expression. The PSORS1C1 haplotype TGCACA and the STARD3 haplotype GG have favorable cumulative effects on NM23 expression. Further, variants in PSORS1C1 were associated with either overall survival (rs556285588, rs3095301, and rs3131003) only or overall survival and recurrence-free survival (rs560052000 and rs541820233) both in HCC patients. Our findings suggested that variants at the PSORS1C1 and STARD3 loci play an important role in NM23 regulation. Moreover, variants in PSORS1C1 are potential biomarkers for the prediction of postoperative clinical outcomes in HBV-related HCC patients. Thus, variants in PSORS1C1 and STARD3 are associated with NM23 expression and clinical outcomes of HBV-related HCC patients, which may be regarded as potential biomarkers for this disease.

Prognostic value and clinicopathologic significance of nm23 in various cancers: A systematic review and meta-analysis

OBJECTIVE

Extensive studies have been carried out to investigate the association between nm23 expression and the prognosis and clinicopathologic significance of various tumors.

METHODS AND MATERIALS

Eligible studies were searched from Embase, China National Knowledge Infrastructure (CNKI), PubMed and Web of Science up to May 2017. In this study, we calculated the pooled hazard ratios (HRs) with 95% confidence intervals (95%CIs) to determine the association between nm23 expression and the prognosis of various tumors.

RESULTS

A total of 49 studies were finally included in the meta-analysis. The pooled HRs were 2.00 (95% CIs: 1.44-2.78) for overall survival (OS), 1.23 (95% CIs: 1.04-1.46) for disease-specific survival or progression-free survival (DFS/PFS), and 2.21 (95% CIs: 1.38-3.57) for survival of recurrence-free survival or metastasis-free survival (RFS/MFS). Moreover, the results indicated that low nm23 expression was significantly correlated with the lymph node metastasis (P = 0.002). For the subgroup analysis, the expression of nm23 in patients at N0 stage was obviously higher than the patients with breast carcinoma at N1-N3 stage [Odds ratio (OR) = 2.07, 95%CI (1.31, 3.26), P = 0.002]. Moreover, the expression of nm23 in the patients at N0 stage was remarkably higher than those at N1-N3 stages in the Chinese patients with breast carcinoma and those with nasopharyngeal carcinoma (P < 0.05). Whereas, no statistical difference was noticed in the expression of nm23 in patients of various age, gender, T stage, histological degree, TNM stage, respectively (P > 0.05).

CONCLUSION

Our study suggests that down-regulation of nm23 is related to poor prognosis in many cancers. The expression of nm23 in cancer tissues may serve as an important factor for evaluating the presence of lymph node metastasis.

Association between NME1 polymorphisms and cancer susceptibility: A meta-analysis based on 1644 cases and 2038 controls

The association between polymorphisms in the nucleoside diphosphate kinase 1 (NME1) gene and overall risk of cancer remains to be elucidated. Here, we performed a meta-analysis of the association between rs16949649, rs2302254, and rs34214448 polymorphisms in the NME1 gene and cancer risk. PubMed, Web of Science, and CNKI databases (as of June 6, 2017) were searched. Eight studies, encompassing 1644 cases and 2038 controls, were selected. The results revealed no significant relationship between NME1 polymorphisms and overall cancer susceptibility. Interestingly, the rs16949649 polymorphism was associated with increased susceptibility to gynecological cancer (heterozygous model: odds ratio [OR] = 1.74, 95% confidence interval [CI] = 1.06-2.86, P = 0.029). The rs2302254 polymorphism was linked to decreased susceptibility to gastric cancer in the other groups (recessive model: OR = 0.53, 95% CI = 0.28-0.98, P = 0.045). The rs34214448 polymorphism correlated significantly with increased susceptibility to non-small cell lung cancer according to all genetic models (P < 0.05) and was linked to decreased risk in cervical cancer (recessive model: OR = 0.51, 95% CI = 0.27-0.94, P = 0.031). Thus, our meta-analysis found rs16949649 associated with increased susceptibility to gynecological cancer and rs2302254 was linked to reduced gastric cancer risk; additional, larger studies are required to confirm these findings.

Epigenetic drivers of tumourigenesis and cancer metastasis

Since the completion of the first human genome sequence and the advent of next generation sequencing technologies, remarkable progress has been made in understanding the genetic basis of cancer. These studies have mainly defined genetic changes as either causal, providing a selective advantage to the cancer cell (a driver mutation) or consequential with no selective advantage (not directly causal, a passenger mutation). A vast unresolved question is how a primary cancer cell becomes metastatic and what are the molecular events that underpin this process. However, extensive sequencing efforts indicate that mutation may not be a causal factor for primary to metastatic transition. On the other hand, epigenetic changes are dynamic in nature and therefore potentially play an important role in determining metastatic phenotypes and this area of research is just starting to be appreciated. Unlike genetic studies, current limitations in studying epigenetic events in cancer metastasis include a lack of conceptual understanding and an analytical framework for identifying putative driver and passenger epigenetic changes. In this review, we discuss the key concepts involved in understanding the role of epigenetic alterations in the metastatic cascade. We particularly focus on driver epigenetic events, and we describe analytical approaches and biological frameworks for distinguishing between "epi-driver" and "epi-passenger" events in metastasis. Finally, we suggest potential directions for future research in this important area of cancer research.

The role of NM23 in patients with colorectal cancer: A systematic review and meta-analysis

This meta-analysis was carried out to evaluate the relationship between NM23 expression and the prognosis of patients with colorectal cancer. We searched PubMed, EMBASE and Web of Science for relevant articles. The pooled odd ratios (ORs) and corresponding 95%CI were calculated to evaluate the prognostic value of NM23 expression in patients with colorectal cancer, and the association between NM23 expression and clinicopathological factors. In total, 2289 patients were pooled from 24 available studies. The incorporative OR combined by 16 studies with overall survival showed that high NM23 expression was associated with better overall survival (OR=0.67, 95%CI: 0.49-0.93, P=0.02, I ²=56%, Ph=0.004). And a new estimate without heterogeneity was produced when only combining high-quality studies (OR=0.70, 95%CI: 0.56-0.86, P=0.0007, I ²=46%). In disease free survival (DFS), we also obtained a good prognosis (OR=0.30, 95%CI: 0.14-0.68, P=0.004). Although we failed to find any significance in N status (P=0.10), elevated NM23 expression was related to well tumor differentiation (OR=0.60, 95%CI: 0.44-0.820, P=0.001) and Dukes' A&B (OR=0.55, 95%CI: 0.32-0.95, P=0.03). These results indicated that over-expressed NM23 might be an indicator of good prognosis, well tumor differentiation and Dukes' A&B of patients with colorectal cancer, but no significance was found in N status.

Prognostic Value of NME1 (NM23-H1) in Patients with Digestive System Neoplasms: A Systematic Review and Meta-Analysis

OBJECTIVE

There is a heated debate on whether the prognostic value of NME1 is favorable or unfavorable. Thus, we carried out a meta-analysis to evaluate the relationship between NME1 expression and the prognosis of patients with digestive system neoplasms.

METHODS

We searched PubMed, EMBASE and Web of Science for relevant articles. The pooled odd ratios (ORs) and corresponding 95%CI were calculated to evaluate the prognostic value of NME1 expression in patients with digestive system neoplasms, and the association between NME1 expression and clinicopathological factors. We also performed subgroup analyses to find out the source of heterogeneity.

RESULTS

2904 patients were pooled from 28 available studies in total. Neither the incorporative OR combined by 17 studies with overall survival (OR = 0.65, 95%CI:0.41-1.03, P = 0.07) nor the pooled OR with disease-free survival (OR = 0.75, 95%CI:0.17-3.36, P = 0.71) in statistics showed any significance. Although we couldn't find any significance in TNM stage (OR = 0.78, 95%CI:0.44-1.36, P = 0.38), elevated NME1 expression was related to well tumor differentiation (OR = 0.59, 95%CI:0.47-0.73, P<0.00001), negative N status (OR = 0.54, 95%CI:0.36-0.82, P = 0.003) and Dukes' stage (OR = 0.43, 95%CI:0.24-0.77, P = 0.004). And in the subgroup analyses, we only find the "years" which might be the source of heterogeneity of overall survival in gastric cancer.

CONCLUSIONS

The results showed that statistically significant association was found between NME1 expression and the tumor differentiation, N status and Dukes' stage of patients with digestive system cancers, while no significance was found in overall survival, disease-free survival and TNM stage. More and further researches should be conducted to reveal the prognostic value of NME1.

Nm23H1 mediates tumor invasion in esophageal squamous cell carcinoma by regulation of CLDN1 through the AKT signaling

Esophageal cancer is a lethal malignancy worldwide. Previously, low expression of metastasis suppressor Nm23H1 and tight junction (TJ) protein claudin-1 (CLDN1) have been known to correlate with poor prognosis in esophageal squamous cell carcinoma (ESCC). However, the molecular interaction between them has not been clarified. In the present study, we first examined the expression of Nm23H1 and CLDN1 in 74 surgical ESCC samples by immunohistochemistry (IHC) to verify their clinicopathologic significance. The biologic effects of Nm23H1 gene silencing or overexpression in ESCC cell lines were then studied by migration and invasion studies, and its regulation on CLDN1 expression was also investigated by western blot analysis. Moreover, the expression of Nm23H1 and CLDN1 at the same invasion front of ESCC tumors was verified by immunofluorescence. The results showed a significantly positive correlation between the expression of Nm23H1 and CLDN1 (γ=0.296, P=0.011) in surgical specimens, especially for the 34 tumors with lymph-node metastasis (γ=0.455, P=0.007). In ESCC cell lines, silencing of Nm23H1 expression markedly enhanced cell invasiveness, accompanied by increased Akt phosphorylation and decreased CLDN1 expression. Conversely, Nm23H1-expressed transfectants exhibited reduced invasiveness, decreased Akt phosphorylation and correspondingly increased CLDN1 expression. Regain of CLDN1 expression in ESCC cells significantly suppressed invasiveness, but did not influence the Akt phosphorylation. Moreover, treating Nm23H1-depleted cells with the AKT inhibitor MK2206 recovered CLDN1 expression, and diminished the invasiveness of ESCC cells. Finally, decreased expressions of both CLDN1 and E-cadherin were observed at the invasive front of the Nm23H1-negative tumors. Overall, our current study documented that reduced Nm23H1 expression activates the AKT signaling pathway, results in diminished CLDN1 expression and potentiates invasiveness of ESCC cells. Enhancement of Nm23H1 expression, inhibition of the AKT signaling pathway, or combined, might be a potential treatment strategy in selective ESCC patients.

Evaluation of serum nucleoside diphosphate kinase A for the detection of colorectal cancer

We previously described the over-expression of nucleoside diphosphate kinase A (NDKA) in tumours and serum from colorectal cancer (CRC) patients, suggesting its use as biomarker. In this study we evaluated the diagnostic accuracy of serum NDKA to detect advanced neoplasia (CRC or advanced adenomas). Furthermore, the performance of NDKA was compared with the faecal immunochemical test (FIT). The study population included a case-control cohort and a screening cohort (511 asymptomatic first-degree relatives of CRC patients that underwent a colonoscopy and a FIT). Serum NDKA was elevated in CRC patients in the case-control cohort (p = 0.002). In the screening cohort, NDKA levels were higher for advanced adenomas (p = 0.010) and advanced neoplasia (p = 0.006) compared to no neoplasia. Moreover, elevated NDKA was associated with severe characteristics of adenomas (≥3 lesions, size ≥ 1 cm or villous component). Setting specificity to 85%, NDKA showed a sensitivity of 30.19% and 29.82% for advanced adenomas and advanced neoplasia, respectively. NDKA combined with FIT (100 ng/mL cut-off) detected advanced adenomas and advanced neoplasia with 45.28% and 49.12% sensitivity, with specificity close to 90%. The combination of serum NDKA and FIT can improve the detection of advanced neoplasia, mainly for lesions located on the proximal colon, in asymptomatic individuals with CRC family-risk.

Reduced NM23 Protein Level Correlates With Worse Clinicopathologic Features in Colorectal Cancers: A Meta-Analysis of Pooled Data

The clinical value of a prominent metastasis suppressor, nonmetastatic protein 23 (NM23), remains controversial. In this study, we examined the correlation between NM23 protein levels and the clinicopathologic features of colorectal cancers (CRC), and assessed the overall prognostic value of NM23 for CRC. Embase, PubMed, Web of Science, and other scientific literature databases were exhaustively searched to identify relevant studies published prior to June 31, 2015. The methodological qualities of selected studies were scored based on the critical appraisal skills program (CASP) criteria, as independently assessed by 2 reviewers. NM23 protein levels in tumor tissues of CRC patients were examined in relation to Dukes stage, differentiation grade, T-stage, lymph node metastasis status, and overall survival (OS). STATA software version 12.0 (Stata Corp, College Station, TX) was used for statistical analysis of data pooled from selected studies. Nineteen cohort studies met the inclusion criteria for present study and contained a combined total of 2148 study subjects. Pooled odd ratios (ORs) for NM23 expression revealed that reduced NM23 protein levels in CRC tumor tissues correlated with Dukes stage C and D (OR = 1.89, 95% CI: 1.06-3.39, P = 0.032), poor differentiation grades (OR = 1.41, 95% CI: 1.03-1.94, P = 0.032), and positive lymph node metastasis status (OR = 3.21, 95% CI: 1.95-5.29, P < 0.001). On the other hand, no such correlations were evident with T-stage T3-4 (OR = 1.56, 95% CI: 0.60-4.06, P = 0.367) or OS (OR = 0.79, 95% CI: 0.58-1.08, P = 0.138). Our analysis of pooled data found that NM23 expression is reduced in CRC tissues and low NM23 levels tightly correlate with higher Dukes stages, poorer differentiation grade, and positive lymph node metastases. However, NM23 levels did not influence the OS in CRC patients.

Regulation of the metastasis suppressor Nm23-H1 by tumor viruses

Metastasis is the most common cause of cancer mortality. To increase the survival of patients, it is necessary to develop more effective methods for treating as well as preventing metastatic diseases. Recent advancement of knowledge in cancer metastasis provides the basis for development of targeted molecular therapeutics aimed at the tumor cell or its interaction with the host microenvironment. Metastasis suppressor genes (MSGs) are promising targets for inhibition of the metastasis process. During the past decade, functional significance of these genes, their regulatory pathways, and related downstream effector molecules have become a major focus of cancer research. Nm23-H1, first in the family of Nm23 human homologues, is a well-characterized, anti-metastatic factor linked with a large number of human malignancies. Mounting evidence to date suggests an important role for Nm23-H1 in reducing virus-induced tumor cell motility and migration. A detailed understanding of the molecular association between oncogenic viral antigens with Nm23-H1 may reveal the underlying mechanisms for tumor virus-associated malignancies. In this review, we will focus on the recent advances to our understanding of the molecular basis of oncogenic virus-induced progression of tumor metastasis by deregulation of Nm23-H1.

Reduced FHIT expression is associated with tumor progression in sporadic colon adenocarcinoma

PURPOSE

Tumor supressor gene FHIT was identified at chromosome 3p14.2 spanning the FRA3B fragile site and is very often inactivated in different types of cancer. The aim of this study was to examine the frequency of FHIT gene LOH as well as FHIT mRNA and protein expression in sporadic colon adenocarcinoma.

METHODS

The results of LOH, real-time qRT-PCR and imunohistochemical analyses were correlated with clinico-pathological characteristics of patients and their tumors in order to evaluate the role of FHIT gene/protein in sporadic colon adenocarcinoma tumorigenesis.

RESULTS

One hundred and thirty one (96.3%) samples were informative for both markers and 33/131 (25.2%) demonstrated LOH. Expression of FHIT mRNA was significantly decreased in colon tumors relative to that in corresponding normal tissue (p = 7.2×10(-6)). Most of the samples (54.0%) were negative for FHIT protein, 26.4% adenocarcinomas showed a weak to moderate immunostaining and 19.6% adenocarcinomas showed strong FHIT immunostaining. No correlation was found between FHIT gene LOH status, mRNA expression or FHIT protein immunostaining and clinico-pathological characteristics. Expression of FHIT mRNA was significantly decreased in FHIT LOH positive tumors (p = 0.027). Patients with LOH negative tumors or FHIT protein positive tumors had longer survival but this findings were not statistically significant.

CONCLUSIONS

Our overall results suggest that reduced expression of FHIT gene may be associated with the progression of these malignant tumors.

Insights into the biology and prevention of tumor metastasis provided by the Nm23 metastasis suppressor gene

Metastatic disease is the major cause of death among cancer patients. A class of genes, named metastasis suppressors, has been described to specifically regulate the metastatic process. The metastasis suppressor genes are downregulated in the metastatic lesion compared to the primary tumor. In this review, we describe the body of research surrounding the first metastasis suppressor identified, Nm23. Nm23 overexpression in aggressive cancer cell lines reduced their metastatic potential in vivo with no significant reduction in primary tumor size. A complex mechanism of anti-metastatic action is unfolding involving several known Nm23 enzymatic activities (nucleotide diphosphate kinase, histidine kinase, and 3'-5' exonuclease), protein-protein interactions, and downstream gene regulation properties. Translational approaches involving Nm23 have progressed to the clinic. The upregulation of Nm23 expression by medroxyprogesterone acetate has been tested in a phase II trial. Other approaches with significant preclinical success include gene therapy using traditional or nanoparticle delivery, and cell permeable Nm23 protein. Recently, based on the inverse correlation of Nm23 and LPA1 expression, a LPA1 inhibitor has been shown to both inhibit metastasis and induce metastatic dormancy.

Nm23-H1 nuclear expression is associated with a more favourable prognosis in laryngeal carcinoma: univariate and multivariate analysis

AIMS

To use image analysis and multivariate analysis to investigate the prognostic significance of Nm23-H1 subcellular localization in a large cohort of laryngeal squamous cell carcinomas (LSCCs).

METHODS AND RESULTS

Nm23-H1 total and nuclear levels were immunohistochemically determined and calculated with an image analysis system in 104 consecutively operated LSCCs. The mean follow-up was 58.3 ± 35.1 months (median 45 months). Total Nm23-H1 levels correlated only with patient stratification by pT (P=0.01). Mean nuclear Nm23-H1 levels were lower in patients with recurrent disease (P=0.01), and disease-free survival (DFS) was longer in patients whose nuclear levels of Nm23-H1 were >2.0% than in those with levels ≤ 2.0% (P=0.019). On multivariate analysis, Nm23-H1 nuclear expression [hazard ratio (HR) 2.59, P=0.005] and N stage (HR 3.60, P=0.0001) were prognostically significant in relation to DFS.

CONCLUSIONS

In LSCC, Nm23-H1 nuclear expression may be useful for identifying patients at higher risk of recurrence after treatment and who might be considered for more aggressive therapy. Further investigations are needed before Nm23-H1 can be considered for use in targeted treatments for LSCC.

Searching for consistently reported up- and down-regulated biomarkers in colorectal cancer: a systematic review of proteomic studies

The cumulative lifetime risk for the development of colorectal cancer in the general population is 6 %. In many cases, early detection by fecal occult blood test is limited regarding sensitivity. Therefore, there is an urgent need for improved diagnostic tests in colorectal cancer. The recent development of high-throughput molecular analytic techniques should allow the rapid evaluation of new diagnostic markers. However, researchers are faced with an overwhelming number of potential markers form numerous colorectal cancer protein expression profiling studies. To address the challenge, we have carried out a comprehensive systematic review of colorectal cancer biomarkers from 13 published studies that compared the protein expression profiles of colorectal cancer and normal tissues. A protein ranking system that considers the number of comparisons in agreement, total sample sizes, average fold-change and direction of differential expression was devised. We observed that some proteins were consistently reported by multiple studies as differentially expressed with a statistically significant frequency (P < 0.05) in cancer versus normal tissues comparison. Our systematic review method identified proteins that were consistently reported as differentially expressed. A review of the top four candidates revealed proteins described previously as having diagnostic value as well as novel candidate biomarkers. These candidates should help to develop a panel of biomarkers with sufficient sensitivity and specificity for the diagnosis of colorectal cancer in a clinical setting.

Increased expression of MDM2 and NM23 are associated with malignant transformation of pleomorphic adenoma

This study was designed to correlate the expression of both MDM2 and NM23 in pleomorphic adenoma (PA) to clinical background, histological features, local recurrence, and metastatic potentiality in this tumor. Expression of MDM2 and NM23 was studied immunohistochemically in 23 cases of PA. Our results demonstrated MDM2 and NM23 overexpression in almost all cases of PA. There was a significant difference of the MDM2 and NM23 mean values between benign PA and both carcinoma-ex PA and metastasizing PA. The results of this study show that the overexpression of NM23 and MDM2 oncoproteins could be used as reliable predictors of malignant progression as well as metastatic potentiality of PA.

Mass spectrometry detection of histidine phosphorylation on NM23-H1

Phosphorylation is a ubiquitous protein post-translational modification that is intimately involved in most aspects of cellular regulation. Currently, most proteomic analyses are performed with phosphorylation searches for serine, threonine, and tyrosine modifications, as the phosphorylated residues of histidine and aspartic acid are acid labile and thus undetectable with most proteomic methodologies. Here, we present a novel buffer system to show histidine phosphorylation of NM23-H1, the product of the first identified putative human metastasis suppressor gene (NME1), which catalyzes the transfer of the γ-phosphate from nucleoside triphosphates to nucleoside diphosphates. On the basis of a pH titration of LC elution buffers and MS/MS identification, recombinant NM23-H1 subjected to autophosphorylation was shown to contain phosphorylated histidine at residue 118 at pH 5 and 6, with each level giving over 75% peptide coverage for identification. The solvent system presented permits the detection of all five possible phosphorylation moieties. Application of histidine and aspartic acid phosphorylation modifications to proteomic analyses will significantly advance the understanding of phosphorylation relay signaling in cellular regulation, including elucidation of the role of NM23-H1 in metastasis.

Nm23-H1/nucleoside diphosphate kinase as a key molecule in breast tumor angiogenesis

BACKGROUND

Neo-angiogenesis seems to be a critical feature of breast tumor growth, migration and metastasis. Inhibition of angiogenesis may provide information regarding treatment. Since angiogenesis is the result of complex processes, controlled by several angiogenic (pro- and/or -anti) factors and their receptors, multiple ways to prevent or retrogress tumor-induced angiogenesis have been proposed. The clinically significant activity of bevacizumab and other antiangiogenic treatments have attracted a great deal of interest.

OBJECTIVE/METHODS

We discuss biological aspects of breast cancer angiogenesis and nucleoside diphosphate kinase (NDPK) as a key molecule in this process.

RESULTS/CONCLUSIONS

In clinical and experimental trials, it was reported that NDPK is inversely related to breast cancer metastasis and angiogenesis. To inhibit the metastatic potential of cancer cells, Nm23-H1/NDP kinase appears to interact with many proteins involved in cellular signal transduction in angiogenesis and tumorigenesis, and therefore reduces the activation of the extracellular signal-regulated kinase (ERK)/MAPK in response to those signals.

Relationship between nm23H1 genetic instability and clinical pathological characteristics in Chinese digestive system cancer patients

AIM: To study the relationship between nm23H1 gene genetic instability and its clinical pathological characteristics in Chinese digestive system cancer patients.

METHODS: Polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) was used to analyze the microsatellite instability (MSI) and loss of heterozygosity (LOH). Immunohistochemistry was employed to detect the expression of nm23H1.

RESULTS: The MSI was higher in TNM stageI + II than in stage III + IV of gastric, colonic and gallbladder carcinomas. The LOH was higher in TNM stage III + IV than in stageI + II of gastric, colonic and hepatocellular carcinomas. Lymphatic metastasis was also observed. The expression of nm23H1 protein was lower in TNM stage III + IV than in stageI + II of these tumors and in patients with lymphatic metastasis.The nm23H1 protein expression was higher in the LOH negative group than in the LOH positive group.

CONCLUSION: MSI and LOH may independently control the biological behaviors of digestive system cancers. MSI could serve as an early biological marker of digestive system cancers. Enhanced expression of nm23H1 protein could efficiently inhibit cancer metastasis and improve its prognosis. LOH mostly appears in late digestive system cancer.

Genetic determinants of cancer metastasis

Metastasis can be viewed as an evolutionary process, culminating in the prevalence of rare tumour cells that overcame stringent physiological barriers as they separated from their original environment and developmental fate. This phenomenon brings into focus long-standing questions about the stage at which cancer cells acquire metastatic abilities, the relationship of metastatic cells to their tumour of origin, the basis for metastatic tissue tropism, the nature of metastasis predisposition factors and, importantly, the identity of genes that mediate these processes. With knowledge cemented in decades of research into tumour-initiating events, current experimental and conceptual models are beginning to address the genetic basis for cancer colonization of distant organs.

Nm23-H1: a metastasis-associated gene

The protein product of nm23-H1 gene has activity of nucleoside diphosphate (NDP) kinase, which catalyzes the phosphorylation of nucleoside diphosphates to the corresponding nucleoside triphosphates. Reductions in nm23 expression have been significantly associated with aggressive behavior in melanoma, breast, colon, and gastric carcinomas. On the contrary, high levels of nm23 gene expression are noted in the advanced stage of thyroid carcinomas and associated with significant reductions in survival for neuroblastoma and osteosarcoma patients. Although expression of nm23/NDP kinase is divergent in various malignant tumors, its reduced expression seems to be related to increased metastatic potential in most carcinoma types. However, it is hypothesized that nm23 may play a tissue-specific role, and that different regulatory mechanisms may act in different tumors. In ovarian carcinoma, nm23-H1/NDP kinase may be correlated with some clinicopathologic characteristics. In cervical cancer, nm23-H1 is probably involved in cervical carcinogenesis and correlated with some aggressive parameters. Overexpression of nm23-H1 protein may indicate poor survival for cervical cancer patients. Other than histidine 118 residue (amino acid sequence 118: histidine) concerned with NDP kinase activity of nm23-H1, serine 120 (amino acid sequence 120: serine) related activity of histidine-dependent protein phosphotransfer was recently reported to be responsible for its biological suppressive effects. To inhibit metastatic potential, nm23-H1 is also demonstrated to co-immunoprecipitate the kinase suppressor of Ras and phosphorylate it, and therefore reduce activation of the extracellular signal-regulated kinase mitogen-activated protein kinase pathway in response to signaling.

Immunohistochemical localization of the NM23 protein in salivary gland neoplasms with distinct biological behavior

The NM23 protein was shown to be associated with metastasis suppression in human malignancies with various tissue origins. However, its association with the metastatic phenotype of salivary gland neoplasms (SGN) remains unknown. To evaluate the role of NM23 in SGN, the expression patterns of NM23 in the following were compared: benign (pleomorphic adenoma) vs malignant (adenoid cystic carcinoma and mucoepidermoid carcinoma) SGN, and primary malignancies with/without evidence of metastasis vs their metastatic implants (MI). The lesions were studied immunohistochemically. NM23 protein was found in the cytoplasm of 75% of benign SGN, 73.3% of primary SGN malignancies with no evidence of metastasis, 86.6% of primary SGN malignancies with evidence of metastasis, and 60% of MI. There was no statistically significant difference in the frequency of NM23-positive cells between benign and primary malignant tumors (p = 0.79), nor between primary malignancies with/without evidence of metastasis and MI (p = 0.51). However, nuclear NM23 protein was restricted to primary SGN malignancies with evidence of metastasis and MI. The presence of nuclear NM23 protein may be a good marker for predicting the metastatic potential of SGN malignancies.

The relationship between the expression of C-erbB-2, nm23 protein in tissue of rectal cancer and its prognostication

AIM: To study the relationship between the expression of C-erbB-2, nm23 protein in tissue of rectal cancer and its infilitration or metastasi.

METHODS: The expression of C-erbB-2, nm23 protein in sample of rectal cancer was detected by immunohistochemistry and its relationship to other factors and its prognostication were analyzed respectively.

RESULTS: The total positive rate of nm23 in tissue of rectal cancer was 78.8%(67/85). According to data of Dukes, the high level was higher in A state (80.9%) than that in C state (42.3%) and D state (27.7%) (P < 0.05), and similar to B state (75.0%) (P > 0.05). The total positive rate of C-erbB-2 was 80%(68/85) and high expression rate in these samples was 54.1%(46/85). It was inverse correlation to expression of nm23. The level of C-erbB-2 in D state was high (77.7%) than that in A state (28.5%) and B state (30.0%) (P < 0.05), and had little difference in C state (76.9%) (P > 0.05). High level of nm23 was more common expressed in tissue of well-differentiated adencarcinoma (80%) than that in poorly differentiated adencarcinoma (25.0%), areolar cancer (10.5%) (P < 0.05), and was similar to moderately differentiated adencarcinoma (71.49%) (P > 0.05). High level of C-erbB-2 was more common expressed in tissue of poorly differentiated adencarcinoma (81.2%) and areolar cancer (78.9%) than that in moderately differentiated adencarcinoma (40%) and well-differentiated adencarcinoma (26.6%) (P < 0.05). There was no significantly difference between in poorly differentiated adencarcinoma and in areolar cancer (P > 0.05). In 41 of 85 patients after treatment for more than five years, high expressive rates of nm23 and C-erbB-2 were 73.1% and 31.7%. In 44 of 85 patients after treatment for less than five years, high expressive rates of nm23 and C-erbB-2 were 34.1% and 84.1%.

CONCLUSION: It has been shown that the expression of nm23 is inverse correlation to that of C-erbB-2. High level of C-erbB-2 is more common in tissue of rectal cancer in C and D state of Dukes, and is associated with infilitration and metastasi of rectal cancer. The prognostication in patients with low expression of nm23 and high expression of C-erbB-2 is common poor.

Identification of a novel VNTR polymorphism in C6orf37 and its association with colorectal cancer risk in Chinese population

BACKGROUND

C6orf37 was a gene up-regulated in colorectal adenoma in our previous study. A variable region of C6orf37 sequence was found when we blasted its full sequence with NCBI nucleotide database.

METHODS

RT-PCR and sequencing were conducted to identify the variable region of C6orf37 as VNTR. DHPLC was applied to detect the VNTR genotypes in 122 colorectal carcinoma patients and 166 healthy controls.

RESULTS

A novel VNTR sequence found in C6orf37 second exon was composed of 15 base pair consensus sequence encoding 5-amino-acid (G-G-D-F-G). The repeat timePOST alleles contain three repeats (a), 4 repeats (b) and 5 repeats (c), respectively, which produced 3 homozygotes (a/a, b/b and c/c) and 3 heterozygotes (a/b, a/c and b/c). a, b, c allele frequencies were 0.145, 0.304, 0.551, respectively in Chinese population. Heterozygosity (H) was 0.583. Polymorphism information content (PIC) was 0.510. The distribution of genotypes and allele frequencies of the VNTR reached no significant difference between patients and healthy controls and there was no correlation between VNTR polymorphism and colorectal cancer clincopathological features.

CONCLUSION

A novel VNTR polymorphism in C6orf37 exists in Chinese population and is not associated with colorectal cancer risk.

NM-23 gene loss of heterozygosity and protein expression in high-stage laryngeal squamous cell carcinomas

Tumor suppressor genes that reduce metastatic potential have been described in a variety of different tumor types. One of the main tumor metastasis suppressor genes is nm-23, which is a nucleoside diphosphate kinase. Two isotypes, nm-23H1 and nm-23H2, have been cloned and map to chromosome 17q21.3. In a variety of tumors, including colon cancer and breast cancer, loss of expression of nm-23 is associated with lymph node metastasis. In other organ systems, however, this relationship is not seen. In head and neck squamous cell carcinomas (HNSCC), there have been conflicting results regarding the association between nm-23 protein expression and metastatic potential. To further explore the tumor metastasis suppressor function of nm-23 in HNSCC, we studied high-stage laryngeal carcinomas, tumors with and without cervical lymph node metastasis for nm-23 protein expression and loss of heterozygosity of the gene locus. Twenty-five cases were included (11 cases with and 14 cases without metastasis). Loss of heterozygosity for the nm-23 gene locus was seen in 7 of 22 (32%) informative tumors. Using immunohistochemistry, most tumors expressed nm-23, though decreased expression was seen in 10 of 25 (40%) cases. Only 2 tumors showed negative expression. We did not find a correlation between either protein expression or loss of heterozygosity with metastatic disease or any other adverse prognostic factors in this group of high-stage laryngeal squamous cell carcinomas. These data imply that nm-23 may be tumor suppressor gene involved in HNSCC but that it may not function as a tumor metastasis suppressor in high-stage laryngeal carcinoma.

STRAD in Peutz-Jeghers syndrome and sporadic cancers

BACKGROUND/AIMS

LKB1 is a tumour suppressor gene that is associated with Peutz-Jeghers syndrome (PJS), a rare autosomal dominant cancer predisposition syndrome. However, germline mutations in the LKB1 gene are found in only about 60% of patients with PJS, suggesting the existence of a second PJS gene. The STRAD gene, encoding an LKB1 interacting protein that activates LKB1, which subsequently leads to polarisation of cells, is an interesting candidate for a second PJS gene and a potential tumour suppressor gene in sporadic carcinomas.

METHODS

The involvement of STRAD in 42 PJS associated tumours (sporadic lung, colon, gastric, and ovarian adenocarcinomas) was studied using loss of heterozygosity (LOH) analysis of eight microsatellite markers on chromosome 17, including TP53, BRCA1, and STRAD markers.

RESULTS

Loss of the marker near the STRAD locus was seen in 13 of 29 informative cases, including all gastric adenocarcinomas. Specific LOH of the STRAD marker was found in four of 29 informative cases. For these patients all exons and exon-intron boundaries of the STRAD gene were sequenced, but no somatic mutations were identified. Furthermore, no germline STRAD mutations were found in 10 patients with PJS and family members without LKB1 germline mutation.

CONCLUSIONS

Despite the frequent occurrence of LOH in the STRAD region, these results indicate that inactivation of the STRAD gene is not essential in the sporadic adenocarcinomas studied, although it is possible that STRAD may be inactivated in different ways. In addition, no evidence was found for the hypothesis that STRAD is a second PJS susceptibility gene.