Association between nm23-H1 expression, proliferation and apoptosis in non-small cell lung carcinomas

The metastasis suppressor protein NM23-H1 modulates the PI3K-AKT axis through interaction with the p110α catalytic subunit

The PI3K pathway is one of the most deregulated pathways in cancer, which is predominantly due to gain of function mutations or altered expression of the PI3KCA gene. This is codified by what is seen for the class I PI3K catalytic subunit p110α, a common feature of many cancers. The metastasis suppressor protein NM23-H1 (NME1), whose ability to suppress the metastasis activities of different tumors has been widely described and was previously reported to alter phosphatidylinositol signaling. Here, we show interaction of NM23-H1 with the p110α subunit and the functional consequence of this interaction. This interaction is predominantly localized at the plasma membrane with some signals seen in the cytoplasmic compartment. Analysis of NM23-H1 levels showed a negative correlation between NM23-H1 expression and Akt phosphorylation, the key marker of PI3K pathway activation. Investigating the functional consequence of this interaction using cell motility and clonogenicity assays showed that expression of NM23-H1 reversed the enhanced migration, invasion, adhesion, and filopodia structure formation in cells expressing the p110α catalytic subunit. A similar trend was seen in anchorage-independent assays. Notably, differential analyses using NM23-H1 mutants which lacked the enzymatic and metastasis suppressor activity, showed no detectable interaction between p110α and the NM23-H1 mutant proteins P96S, H118F, and S120G, as well as no dysregulation of the PI3K-AKT axis.

nm23 regulates decidualization through the PI3K-Akt-mTOR signaling pathways in mice and humans

STUDY QUESTION

Does nm23 have functional significance in decidualization in mice and humans?

SUMMARY ANSWER

nm23 affects decidualization via the phosphoinositide 3 kinase/mammalian target of rapamycin (PI3K-Akt-mTOR) signaling pathways in mouse endometrial stromal cells (ESCs; mESCs) and human ESCs.

WHAT IS KNOWN ALREADY

The function of nm23 in suppressing metastasis has been demonstrated in a variety of cancer types. nm23 also participates in the control of DNA replication and cell proliferation and differentiation.

STUDY DESIGN, SIZE AND DURATION

We first analyzed the expression profile of nm23 in mice during early pregnancy (n = 6/group), pseudopregnancy (n = 6/group) and artificial decidualization (n = 6/group) and in humans during the menstrual cycle phases and the first trimester. We then used primary cultured mESCs and a human ESC line, T-HESC, to explore the hormonal regulation of nm23 and the roles of nm23 in in vitro decidualization, and as a possible mediator of downstream PI3K-Akt-mTOR signaling pathways.

PARTICIPANTS/MATERIALS, SETTINGS AND METHODS

We evaluated the dynamic expression of nm23 in mice and humans using immunohistochemistry, western blot and real-time quantitative RT-PCR (RT-qPCR). Regulation of nm23 by steroid hormones was investigated in isolated primary mESCs and T-HESCs by western blot. The effect of nm23 knockdown (using siRNA) on ESC proliferation was analyzed by 5-ethynyl-2'-deoxyuridine staining (EdU) and proliferating cell nuclear antigen protein (PCNA) expression. The influence of nm23 expression on the differentiation of ESCs was determined by RT-qPCR using the mouse differentiation markers decidual/trophoblast PRL-related protein (dtprp, also named prl8a2) and prolactin family 3 subfamily c member 1 (prl3c1) and the human differentiation markers insulin-like growth factor binding protein 1 (IGFBP1) and prolactin (PRL). The effects of nm23 siRNA (si-nm23) and the PI3K inhibitor LY294002 on the downstream effects of nm23 on the PI3K-Akt-mTOR signaling pathway were estimated by western blot.

MAIN RESULTS AND THE ROLE OF CHANCE

NM23-M1 was specifically expressed in the decidual zone during early pregnancy and in artificially induced deciduoma, and NM23-H1 was strongly expressed in human first trimester decidua. The expression of nm23 was upregulated by oestradiol and progesterone (P < 0.05 versus control) in vitro in mESCs and T-HESC, and this was inhibited by their respective receptor antagonists, ICI 182,780 and RU486. Mouse and human nm23 knockdown decreased ESC proliferation and differentiation (P < 0.05 versus control). The PI3K-Akt-mTOR signaling pathways were downstream mediators of nm23 in mESCs and T-HESCs decidualization.

LIMITATIONS AND REASONS FOR CAUTION

Whether the nm23 regulates decidualization via the activation of AMPK, RAS, PKA, STAT3 or other signaling molecules remains to be determined. The role of nm23 in decidualization was tested in vitro only.

WIDER IMPLICATIONS OF THE FINDINGS

Results demonstrate that nm23 plays a vital role in decidualization in mice and humans and that nm23 gene expression is hormonally regulated. The downregulation of nm23 in decidua during the first trimester may be associated with infertility in women.

STUDY FUNDING/COMPETING INTERESTS

This study was supported by the National Natural Science Foundation of China (grant nos. 81370731, 31571551 and 31571190), the Science and Technology Project of Chongqing Education Committee (KJ130309), open funding by the Chongqing Institute for Family Planning (1201) and the Excellent Young Scholars of Chongqing Medical University (CQYQ201302). The authors have no conflicts of interest to declare.

NDK-1, the homolog of NM23-H1/H2 regulates cell migration and apoptotic engulfment in C. elegans

Abnormal regulation of cell migration and altered rearrangement of cytoskeleton are characteristic of metastatic cells. The first described suppressor of metastatic processes is NM23-H1, which displays NDPK (nucleoside-diphosphate kinase) activity. To better understand the role of nm23 genes in cell migration, we investigated the function of NDK-1, the sole Caenorhabditis elegans homolog of group I NDPKs in distal tip cell (DTC) migration. Dorsal phase of DTC migration is regulated by integrin mediated signaling. We find that ndk-1 loss of function mutants show defects in this phase. Epistasis analysis using mutants of the α-integrin ina-1 and the downstream functioning motility-promoting signaling module (referred to as CED-10 pathway) placed NDK-1 downstream of CED-10/Rac. As DTC migration and engulfment of apoptotic corpses are analogous processes, both partially regulated by the CED-10 pathway, we investigated defects of apoptosis in ndk-1 mutants. Embryos and germ cells defective for NDK-1 showed an accumulation of apoptotic cell corpses. Furthermore, NDK-1::GFP is expressed in gonadal sheath cells, specialized cells for engulfment and clearence of apoptotic corpses in germ line, which indicates a role for NDK-1 in apoptotic corpse removal. In addition to the CED-10 pathway, engulfment in the worm is also mediated by the CED-1 pathway. abl-1/Abl and abi-1/Abi, which function in parallel to both CED-10/CED-1 pathways, also regulate engulfment and DTC migration. ndk-1(-);abi-1(-) double mutant embryos display an additive phenotype (e. g. enhanced number of apoptotic corpses) which suggests that ndk-1 acts in parallel to abi-1. Corpse number in ndk-1(-);ced-10(-) double mutants, however, is similar to ced-10(-) single mutants, suggesting that ndk-1 acts downstream of ced-10 during engulfment. In addition, NDK-1 shows a genetic interaction with DYN-1/dynamin, a downstream component of the CED-1 pathway. In summary, we propose that NDK-1/NDPK might represent a converging point of CED-10 and CED-1 pathways in the process of cytoskeleton rearrangement.

Prognostic impact of nm23-H1 and PCNA expression in pathologic stage I non-small cell lung cancer

INTRODUCTION

The purpose of this study was to evaluate the value of nm23-H1 and proliferating cell nuclear antigen (PCNA) expression as well as other confirmed prognostic factors in predicting the clinical outcome after definitive surgery of pathologic stage I non-small cell lung cancer (NSCLC).

METHODS

Four hundred fifty-two consecutive and non-selected patients who underwent definitive surgery for stage I NSCLC were included in this study. Formalin-fixed paraffin-embedded specimens were stained for nm23-H1 and PCNA, the correlation between the staining and its clinicopathological parameters, and its prognostic power were analyzed statistically.

RESULTS

Of the 452 patients studied, 320 cases (70.8%) were high expression for nm23-H1. A total of 182 carcinomas (40.3%) were PCNA high expression tumors. PCNA expression correlated with serum CEA level (P < 0.001), and differentiation (P < 0.001). In univariate analysis by log-rank test, serum CEA level, pT stage, differentiation, nm23-H1 expression, and PCNA expression were significant prognostic factors (P = 0.037, 0.021, <0.001, 0.042, and 0.014, respectively). In multivariate analysis, pT stage and nm23-H1 expression maintained its independent prognostic influence on overall survival (P = 0.041 and 0.003, respectively).

CONCLUSIONS

nm23-H1 may be a good biomarker to be applied in clinic to predict the prognosis of patients with completely resected pathologic stage I NSCLC.

Association of EcoRI polymorphism of the metastasis-suppressor gene NME1 with susceptibility to and severity of non-small cell lung cancer

BACKGROUND

Human lung cancer cells with high metastatic potential show reduced expression of the metastasis-suppressor gene NME1. However, the biallelic EcoRI polymorphism of this gene has not been studied in lung cancer. With this allelic association study, we aimed to investigate the impact of polymorphisms of the NME1 gene on the susceptibility to and severity of non-small cell lung cancer (NSCLC).

METHODS

Through a case-control study design, genomic DNA samples of 255 NSCLC patients and 303 controls, who were age and sex-matched and recruited from the health check-up unit, were subjected to polymorphism analysis with polymerase chain reaction-restriction fragment length polymorphism technique. The validity of this technique was proven by direct sequencing of polymerase chain reaction products. Statistical analyses were conducted to explore the contribution of polymorphism of the metastasis-suppressor gene NME1 in the susceptibility to and severity of NSCLC.

RESULTS

Overall, the genotype frequencies of NME1 gene were significantly different between lung cancer patients and controls (p < 0.0001), and also different between patients with lung cancers of various stages (p < 0.0001). Logistic regression analysis revealed that higher odds ratios (ORs) for lung cancer were seen in patients homozygous (+/+) for variant allele (an OR of 4.02, 95% CI 2.39-6.76; p < 0.0001). Patients carrying a variant polymorphic homozygote (+/+) also had a tendency to advanced disease (p = 0.001).

CONCLUSION

A significant association between the polymorphisms of NME1 gene and the susceptibility to and severity of lung cancer was demonstrated.

nm23-H1 expression and loss of heterozygosity in colon adenocarcinoma

BACKGROUND

The discovery that genetic alterations in oncogenes and tumour suppressor genes accompany tumour formation in many human tumours has encouraged the search for genes that promote or suppress tumour spread and metastasis; nm23 is a promising candidate for a metastasis suppressing gene.

AIMS

To evaluate whether expression of nm23-H1 protein or loss of heterozygosity (LOH) of the nm23-H1 gene is associated with colon cancer progression.

MATERIALS/METHODS

Paraffin wax embedded tissue sections were analysed immunohistochemically. DNA isolated from normal and tumour tissue was used for LOH analysis using a variable nucleotide tandem repeat (VNTR) marker located in the untranslated 5' region of the nm23-H1 gene. RNA isolated from tumour and normal tissue was used for "real time" RT-PCR.

RESULTS

Of 102 adenocarcinomas examined, 58.8% stained weakly for nm23-H1 protein. There was a negative correlation between nm23-H1 positivity and tumour histological grade. In VNTR analysis, 70.2% of patients were informative and 27.4% of tumours had nm23-H1 LOH. There was a positive correlation between nm23-H1 LOH and both tumour histological grade and Dukes's stage. Expression of nm23-H1 mRNA was increased in 22 of 30 colon tumours compared with normal tissue. No significant correlation was found between nm23-H1 mRNA expression and histological grade or Dukes's stage of tumours.

CONCLUSIONS

These findings suggest that nm23-H1 protein expression in early stages may have a role in suppressing metastasis in sporadic colon cancer, whereas at a later stage both reduced nm23-H1 protein expression and LOH of the nm23-H1 gene may play role in colon cancer progression and metastasis.

Dominant Papillary Subtype Is a Significant Predictor of the Response to Gefitinib in Adenocarcinoma of the Lung

PURPOSE

Gefitinib (IRESSA; AstraZeneca, Osaka, Japan) shows excellent antitumor activity against advanced non-small-cell lung cancer, especially for the treatment of adenocarcinoma. However, the predictive factors for the response to gefitinib are still controversial. The aim of this study was to identify the clinicopathological and immunohistochemical features that are favorable to the use of gefitinib in adenocarcinoma patients.

EXPERIMENTAL DESIGN

Between June 2002 and October 2003, 36 adenocarcinoma patients who experienced a relapse after surgical resection were treated with gefitinib at our hospital. The histologic patterns of the tumors were divided into four distinctive subtypes according to the revised World Health Organization histologic classification, and the dominant histologic subtype for the maximum cut surface of each resected specimen was documented. Association between the response to gefitinib and the clinicopathological features or immunohistochemical expression of epidermal growth factor receptor (EGFR), phosphorylated EGFR, or c-erbB-2 were then investigated.

RESULTS

A significant association between the response to gefitinib and dominant papillary subtype findings was observed (P = 0.0021); the survival time of papillary subtype patients was also significantly prolonged compared with that of non-papillary subtype patients (P = 0.03). No other clinicopathological features or the expression of EGFR, phosphorylated EGFR, or c-erbB-2 were associated with the response to gefitinib.

CONCLUSIONS

The results of the present study indicate that dominant papillary subtype findings of lung adenocarcinomas can be an important predictor of the response to gefitinib. Thus, this type of adenocarcinoma might be susceptible to postoperative adjuvant treatment with gefitinib.

Co-downregulation of PTEN, KAI-1, and nm23-H1 tumor/metastasis suppressor proteins in non-small cell lung cancer

The multistep process of carcinogenesis implies the accumulation of multiple molecular defects. Alteration of tumor suppressor and metastasis suppressor genes are the important steps. Increasing experimental evidence indicates that decreased expression of tumor-metastasis/suppressor genes and gene products are involved in the progression of a variety of human malignancies. In the present study, we have extended this analysis to non-small cell lung carcinomas (NSCLC). The expression and prognostic significance of the tumor suppressor gene PTEN and metastasis suppressor genes nm23-H1 and KAI-1 was evaluated in NSCLCs. Immunohistochemical staining was performed on formalin-fixed, paraffin-embedded tissues from 53 bronchogenic adenocarcinomas and 51 squamous cell carcinomas using monoclonal antibodies against PTEN, nm23H-1, and KAI-1 proteins. Immunohistochemical results were correlated with tumor stage, grade, lymph nodes positivity, metastasis, and patient survival. Significant co-expression of PTEN, nm23-H1 and KAI-1 was observed in NSCLC (P<.001 to .002). The immunohistochemical expression of these proteins was significantly higher in stages 1 and 2 compared with stages 3 and 4 (P=.04 for PTEN and KAI-1, P=.039 for nm23-H1). When all stages were considered together, loss of immunoreactivity for PTEN, nm23-H1 and KAI-1 was found in advanced NCSCLs (P=.015 for PTEN, P=.001 for KAI-1, P=.004 for nm23-H1), which is suggestive of co-downregulation of these proteins in the process of tumor progression. On multivariate analysis, negative staining for PTEN (P=.014), KAI-1 (P=.034), and nm23-H1 (a trend toward association for nm23-H1 reached near significance P=.08) correlated with disease-related death. Positive lymph node status was associated with negative immunostaining for PTEN (P=.007) but no correlation was observed for nm23-H1 and KAI-1. Loss of expression was linked to distant metastasis (P=.006 for PTEN, P=.002 for nm23H1, P=.001 for KAI-1). On multivariate analysis, co-downregulation of PTEN (P=.009), KAI-1 (P=.02), and nm23-H1 (P=.011) independently predicted shortened survival in NSCLC. Although NSCLC exhibits strong co-expression of PTEN, nm23-H1 and KAI-1, there is a loss of these proteins in high-stage tumors. Co-downregulation of PTEN, KAI-1, and nm23-H1 significantly correlates with distant metastasis and predicts shortened survival. Our study supports a role of these tumor suppressor and metastasis suppressor genes in the evolution and progression of NSCLC.

Molecular pathology of tumor metastasis. I. Predictive pathology

Millennium reviews of oncology agreed that the last century produced major developments mainly in the management of the primary tumor, but despite all of these results, cancer still remains among the leading causes of death due to the failure of clinical management of disseminated disease. This failure is primarily due to the lack of detailed information on the molecular mechanisms of tumor metastasis. Therefore, one of the hottest fields in experimental oncology is metastasis research, which provides more and more information about the molecular mechanisms. However, this information is fragmented and is not yet exploited in clinical practice. A new field of diagnostic pathology recently emerged, which translates basic research data to diagnostic practice to provide clinically relevant information on the biological potential (in this case metastatic potential) of the malignant tumors. Since tumor cell-extracellular matrix interactions are key features of tumor dissemination, expression of genes responsible for them can define the metastatic potential of malignant tumors. This review summarizes our recent knowledge on the metastatic geno- and phenotype of major human solid tumors: lung, colon, breast, prostate cancers and malignant melanoma.