Down-regulated nucleoside diphosphate kinase nm23-H1 expression is unrelated to high-risk human papillomavirus but associated with progression of cervical intraepithelial neoplasia and unfavourable prognosis in cervical cancer

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.

NDPKA is not just a metastasis suppressor - be aware of its metastasis-promoting role in neuroblastoma

NDPK-A, encoded by nm23-H1 (also known as NME1) was the first metastasis suppressor discovered. Much of the attention has been focused on the metastasis-suppressing role of NDPK-A in human tumors, including breast carcinoma and melanoma. However, compelling evidence points to a metastasis-promoting role of NDPK-A in certain tumors such as neuroblastoma and lymphoma. To balance attention on this contrariety of NDPK-A in different cancer types, this review addresses the metastasis-promoting role of NDPK-A in neuroblastoma. Neuroblastoma is an embryonic tumor, arising from neural crest cells that fail to differentiate into the sympathetic nervous system. We summarize and discuss nm23-H1 genetics and the prognosis of neuroblastoma, structural and functional changes associated with the S120G mutation of NDPK-A, as well as the evidence supporting the role of NDPK-A as a metastasis promoter. Also discussed are the NDPK-A relevant molecular determinants of neuroblastoma metastasis, and metastasis-relevant neural crest development. Because of NDPK-A's dichotomous role in tumor metastasis as both a suppressor and a promoter, tumor genome/exome profiles are necessary to identify the molecular drivers of metastasis in the NDPK-A network for developing tumor-specific therapies.

High Expression of Human Telomerase Reverse Transcriptase in High-Grade Intraepithelial Neoplasia and Carcinoma of Uterine Cervix and Its Correlation With Human Papillomavirus Infection

Most of cervical intraepithelial neoplasia 1 (CIN 1) will regress and 12% to 40% of high-grade CIN may progress to squamous cell carcinoma (SCC) of the uterine cervix. However, the differentiation of CIN 1 and high-grade CIN is sometimes controversial among pathologists. Human telomerase reverse transcriptase (hTERT) is therefore applied to detect the differences among normal, CIN 1, high-grade CIN, and SCC tissues of uterine cervix. One hundred six cervical specimens were collected for immunohistochemical study of hTERT. These data were compared with the human papillomavirus (HPV) DNA status. Expression of hTERT in high-grade CIN increased significantly compared to that in CIN 1 ( P < .001). A positive relationship was found between high hTERT expression and degree of malignant transformation ( P < .001). Most of the cases with high hTERT expression tested positive for the high-risk HPV groups. High hTERT expression was detected in 88.73% of the samples with cervical high-grade CIN or SCC. Low hTERT expression was found in 94.29% of low-grade CIN or normal tissues. Furthermore, 96.92% of the cervical tissues with high hTERT expression were high-grade CIN or SCC. A total of 80.49% of samples with low hTERT expression were low-grade CIN or normal tissues. A significantly increased hTERT expression between CIN 1 and high-grade CIN exhibits a critical progression in cervical carcinogenesis. hTERT can be offered as additional molecular information correlated with more severe dysplasia and SCC. Furthermore, this increased hTERT expression is correlated whigh-risk HPVs infection.

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.

Characterization of NOL7 gene point mutations, promoter methylation, and protein expression in cervical cancer

NOL7 is a putative tumor suppressor gene localized to 6p23, a region with frequent loss of heterozygosity in a number of cancers, including cervical cancer (CC). We have previously demonstrated that reintroduction of NOL7 into CC cells altered the angiogenic phenotype and suppressed tumor growth in vivo by 95%. Therefore, to understand its mechanism of inactivation in CC, we investigated the genetic and epigenetic regulation of NOL7. NOL7 mRNA and protein levels were assessed in 13 CC cell lines and 23 consecutive CC specimens by real-time quantitative polymerase chain reaction, western blotting, and immunohistochemistry. Methylation of the NOL7 promoter was analyzed by bisulfite sequencing and mutations were identified through direct sequencing. A CpG island with multiple CpG dinucleotides spanned the 5' untranslated region and first exon of NOL7. However, bisulfite sequencing failed to identify persistent sites of methylation. Mutational sequencing revealed that 40% of the CC specimens and 31% of the CC cell lines harbored somatic mutations that may affect the in vivo function of NOL7. Endogenous NOL7 mRNA and protein expression in CC cell lines were significantly decreased in 46% of the CC cell lines. Finally, immunohistochemistry demonstrated strong NOL7 nucleolar staining in normal tissues that decreased with histologic progression toward CC. NOL7 is inactivated in CC in accordance with the Knudson 2-hit hypothesis through loss of heterozygosity and mutation. Together with evidence of its in vivo tumor suppression, these data support the hypothesis that NOL7 is the legitimate tumor suppressor gene located on 6p23.

Targeting tumor metastasis by regulating Nm23 gene expression

The Nm23 gene is a metastatic suppressor identified in a melanoma cell line and expressed in different tumors where their levels of expression are associated with reduced or increased metastatic potential. Nm23 is one of the over 20 metastasis suppressor genes (MSGs) confirmed in vivo. It is highly conserved from yeast to human, implying a critical developmental function. Tumors with alteration of the p53 gene and reduced expression of the Nm23 gene are more prone to metastasis. Nm23-H1 has 3'-5' exonuclease activity. This review focuses on the role of Nm23 in cancer progression and also a potential novel target for cancer therapy.

Regulation of Nm23-H1 and cell invasiveness by Kaposi's sarcoma-associated herpesvirus

The Kaposi's sarcoma-associated herpesvirus (KSHV) is the causative agent of Kaposi's sarcoma (KS), and the induction of an invasive cellular phenotype by KSHV following de novo infection is an important pathogenic component mediating tumor progression. The metastasis suppressor gene known as Nm23-H1 regulates tumor cell invasiveness, but whether KSHV itself regulates Nm23-H1 expression or subcellular localization, and whether this impacts cell invasiveness, has not been established. We found that KSHV increases expression and nuclear translocation of Nm23-H1 and that nuclear translocation of Nm23-H1 is regulated by the KSHV-encoded latency-associated nuclear antigen (LANA). Moreover, activation of the Ras-BRaf-MAPK (mitogen-activated protein kinase) signal transduction pathway, secretion of promigratory factors associated with this pathway, and cell invasiveness are dependent on KSHV regulation of Nm23-H1. Finally, induction of cytoplasmic overexpression of Nm23-H1 using a pharmacologic inhibitor of DNA methylation reduced KSHV-associated Ras-BRaf-MAPK pathway activation and suppressed KSHV-induced invasiveness. These data provide the first evidence for KSHV regulation of Nm23-H1 as a mechanism for KSHV induction of an invasive cellular phenotype and support the potential utility of targeting Nm23-H1 as a therapeutic approach for the treatment of KS.

Identification and characterization of the human NOL7 gene promoter

NOL7 is a candidate tumor suppressor gene that localizes to 6p23, a chromosomal region frequently associated with loss of heterozygosity in a number of malignancies including cervical cancer (CC). Re-expression of NOL7 in CC cells suppresses in vivo tumor growth by 95% and alters the angiogenic phenotype by modulating the expression of VEGF and TSP1. Here, we describe the determination of two NOL7 transcriptional start sites (TSS), the cloning of its regulatory promoter region, and the identification of transcription factors that regulate its expression. Using 5' Rapid amplification of complementary DNA ends (RACE), two transcriptional start sites were identified. Deletion analysis determined that the essential elements required for the optimal promoter activity of NOL7 were 560 bp upstream of its translation start site. In silico analysis suggested that the promoter region contained potential binding sites for the SP1, c-Myc and RXRalpha transcription factors as well as an overall GC content of greater than 60%. Chromatin immunoprecipitation (ChIP) confirmed that SP1, c-Myc and RXRalpha bound to the NOL7 promoter region. Finally, we demonstrate that NOL7 expression was positively regulated by c-Myc and RXRalpha. These results demonstrate that the NOL7 promoter region possesses each of the key elements of a TATA-less promoter. In addition, the positive regulation of NOL7 by c-Myc and RXRalpha provides additional mechanistic insights into the potential role of NOL7 in CC and other malignancies.

Clinical-translational approaches to the Nm23-H1 metastasis suppressor

Nm23-H1 significantly reduces metastasis without effects on primary tumor size and was the first discovered metastasis suppressor gene. At least three mechanisms are thought to contribute to the metastasis-suppressive effect of Nm23-H1: (a) its histidine kinase activity toward ATP-citrate lyase, aldolase C, and the kinase suppressor of ras, with the last inactivating mitogen-activated protein kinase signaling; (b) binding proteins that titer out "free" Nm23-H1 and inhibit its ability to suppress metastasis; and (c) altered gene expression downstream of Nm23-H1, particularly an inverse association with the lysophosphatidic acid receptor endothelial differentiation gene-28 (EDG2). Most metastasis suppressor genes, including Nm23-H1, affect metastatic colonization, which is the outgrowth of tumor cells in distant locations; therefore, they are of high translational interest. A phase II trial is ongoing to test the hypothesis that a compound, high-dose medroxyprogesterone acetate (MPA), used as an unconventional gluocorticoid, will stimulate breast cancer cells to reexpress Nm23-H1 and limit subsequent metastatic colonization.

Concurrent high expression of human telomerase reverse transcriptase and human nonmetastatic clone 23 in high-grade squamous intraepithelial neoplasia and squamous cell carcinoma of uterine cervix

Human telomerase reverse transcriptase (hTERT) and human nonmetastatic clone 23 (nm23-H1) may be separately involved in tumor progression of uterine cervix. We therefore investigate the correlations of hTERT and nm23-H1 in cervical carcinogenesis and further check their application. One hundred and twenty-eight cervical tissues, including 48 squamous cell carcinoma (SCC), 36 high-grade cervical intraepithelial neoplasia (CIN) (CIN 2 and CIN 3), 20 low-grade CIN 1, and 24 normal cases, were collected for immunohistochemical expression of hTERT and nm23-H1. Spearman rank correlation analysis was applied to assess their correlation in these samples. The Fisher exact or Chi-square test was used to evaluate the expression of hTERT or nm23-H1 among each subgroup. The sensitivity, specificity, positive and negative predictive values (PPV and NPV), and accuracy of hTERT and/or nm23-H1 were calculated for the prediction of high-grade CIN and SCC. We found normal cervix and CIN 1 samples had concurrent low expression of hTERT and nm23-H1, whereas high-grade CIN and SCC samples had concurrent high immunoreactivities. The hTERT alone and hTERT or nm23-H1 in combination had better sensitivity, NPV, and accuracy. The nm23-H1 alone as well as hTERT and nm23-H1 in combination had better specificity and PPV. Our results reveal a significantly positive relationship between expression of hTERT and nm23-H1 in normal and neoplastic tissues of uterine cervix. We suggest high expression of hTERT alone and hTERT or nm23-H1 in combination can be offered additional molecular information correlated with high-grade CIN and SCC.

Up-regulation of proliferating cell nuclear antigen (PCNA) is closely associated with high-risk human papillomavirus (HPV) and progression of cervical intraepithelial neoplasia (CIN), but does not predict disease outcome in cervical cancer

OBJECTIVE

Proliferating cell nuclear antigen (PCNA) is essential for DNA replication of mammalian cells and their small DNA tumour viruses. The E7 oncoprotein of high-risk human papillomavirus (HPV) is known to activate PCNA, shown to be up-regulated in CIN and cervical cancer (CC), but still incompletely studied as an intermediate endpoint marker in this disease.

MATERIAL AND METHODS

As part of our HPV-PathogenISS study, a series of 150 CCs and 152 CIN lesions were examined using immunohistochemical (IHC) staining for PCNA, and tested for HPV using PCR with three primer sets (MY09/11, GP5+/GP6+, SPF). Follow-up data were available from all SCC patients, and 67 of the CIN lesions had been monitored with serial PCR for HPV after cone treatment.

RESULTS

Expression of PCNA increased in parallel with the grade of CIN, with major up-regulation upon transition to CIN3 (OR 21.77; 95%CI 6.59-71.94) (p = 0.0001). Intense PCNA expression was 100% specific indicator of CIN, with 100% PPV, but suffers from low sensitivity (34.8%) and NPV (10.8%). PCNA expression was also significantly associated to HR-HPV with OR 3.02 (95%CI 1.71-5.34) (p = 0.0001), and this association was not confounded by the histological grade (Mantel-Haenszel common OR = 2.03; 95%CI 1.06-3.89) (p = 0.033). Expression of PCNA did not predict clearance/persistence of HR-HPV after treatment of CIN, and it was not a prognostic predictor in CC in univariate or in multivariate analysis.

CONCLUSIONS

Up-regulation of PCNA was closely associated with HR-HPV and progressive CIN, most feasibly explained by the abrogation of normal cell cycle control by the E7 ongogene, reverting the p21(Cip1)-mediated inhibition of PCNA. However, the fact that PCNA is also expressed in normal squamous epithelium precludes the use of this marker as a potential screening tool for CC.