Clinical significance of nm23-H1 proteins expressed on cell surface in non-Hodgkin's lymphoma

Extracellular Vesicle-Mediated Metastasis Suppressors NME1 and NME2 Modify Lipid Metabolism in Fibroblasts

Simple Summary

Communication between cancer and stromal cells involves paracrine signalling mediated by extracellular vesicles (EVs). EVs transmit essential factors among cells of the tumour microenvironment. EVs derived from both cancer and stromal cells have been implicated in tumour progression. In this study, we focused on the first identified metastasis suppressor NME1, and on its close homolog NME2, and investigated their function in EVs in the interplay between cancer and stromal cells.

Abstract

Nowadays, extracellular vesicles (EVs) raise a great interest as they are implicated in intercellular communication between cancer and stromal cells. Our aim was to understand how vesicular NME1 and NME2 released by breast cancer cells influence the tumour microenvironment. As a model, we used human invasive breast carcinoma cells overexpressing NME1 or NME2, and first analysed in detail the presence of both isoforms in EV subtypes by capillary Western immunoassay (WES) and immunoelectron microscopy. Data obtained by both methods showed that NME1 was present in medium-sized EVs or microvesicles, whereas NME2 was abundant in both microvesicles and small-sized EVs or exosomes. Next, human skin-derived fibroblasts were treated with NME1 or NME2 containing EVs, and subsequently mRNA expression changes in fibroblasts were examined. RNAseq results showed that the expression of fatty acid and cholesterol metabolism-related genes was decreased significantly in response to NME1 or NME2 containing EV treatment. We found that FASN (fatty acid synthase) and ACSS2 (acyl-coenzyme A synthetase short-chain family member 2), related to fatty acid synthesis and oxidation, were underexpressed in NME1/2-EV-treated fibroblasts. Our data show an emerging link between NME-containing EVs and regulation of tumour metabolism.

A novel kinase function of a nucleoside-diphosphate-kinase homologue in Porphyromonas gingivalis is critical in subversion of host cell apoptosis by targeting heat-shock protein 27

We have previously shown that a homologue of a conserved nucleoside-diphosphate-kinase (Ndk) family of multifunctional enzymes and secreted molecule in Porphyromonas gingivalis can modulate select host molecular pathways including downregulation of reactive-oxygen-species generation to promote bacterial survival in human gingival epithelial cells (GECs). In this study, we describe a novel kinase function for bacterial effector, P. gingivalis-Ndk, in abrogating epithelial cell death by phosphorylating heat-shock protein 27 (HSP27) in GECs. Infection by P. gingivalis was recently suggested to increase phosphorylation of HSP27 in cancer-epithelial cells; however, the mechanism and biological significance of antiapoptotic phospho-HSP27 during infection has never been characterised. Interestingly, using glutathione S-transferase-rNdk pull-down analysed by mass spectrometry, we identified HSP27 in GECs as a strong binder of P. gingivalis-Ndk and further verified using confocal microscopy and ELISA. Therefore, we hypothesised P. gingivalis-Ndk can phosphorylate HSP27 for inhibition of apoptosis in GECs. We further employed P. gingivalis-Ndk protein constructs and an isogenic P. gingivalis-ndk-deficient-mutant strain for functional examination. P. gingivalis-infected GECs displayed significantly increased phospho-HSP27 compared with ndk-deficient-strain during 24 hr infection. Phospho-HSP27 was significantly increased by transfection of GFP-tagged-Ndk into uninfected-GECs, and in vitro phosphorylation assays revealed direct phosphorylation of HSP27 at serines 78 and 82 by P. gingivalis-Ndk. Depletion of HSP27 via siRNA significantly reversed resistance against staurosporine-mediated-apoptosis during infection. Transfection of recombinant P. gingivalis-Ndk protein into GECs substantially decreased staurosporine-induced-apoptosis. Finally, ndk-deficient-mutant strain was unable to inhibit staurosporine-induced Cytochrome C release/Caspase-9 activation. Thus, we show for the first time the phosphorylation of HSP27 by a bacterial effector-P. gingivalis-Ndk-and a novel function of Ndks that is directly involved in inhibition of host cell apoptosis and the subsequent bacterial survival.

Extracellular NME proteins: a player or a bystander?

The Nm23/NME gene family has been under intensive study since Nm23H1/NME1 was identified as the first metastasis suppressor. Inverse correlation between the expression levels of NME1/2 and prognosis has indeed been demonstrated in different tumor cohorts. Interestingly, the presence of NME proteins in the extracellular environment in normal and tumoral conditions has also been noted. In many reported cases, however, these extracellular NME proteins exhibit anti-differentiation or oncogenic functions, contradicting their canonical anti-metastatic action. This emerging field thus warrants further investigation. In this review, we summarize the current understanding of extracellular NME proteins. A role in promoting stem cell pluripotency and inducing development of central nervous system as well as a neuroprotective function of extracellular NME have been suggested. Moreover, a tumor-promoting function of extracellular NME also emerged at least in some tumor cohorts. In this complex scenario, the secretory mechanism through which NME proteins exit cells is far from being understood. Recently, some evidence obtained in the Drosophila and cancer cell line models points to the involvement of Dynamin in controlling the balance between intra- and extracellular levels of NME. Further analyses on extracellular NME will lead to a better understanding of its physiological function and in turn will allow understanding of how its deregulation contributes to carcinogenesis.

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.

Inhibition of nm23-H1 gene expression in chronic myelogenous leukemia cells

For solid tumors of a malignant origin, the expression of the nm23-H1 gene is a positive prognostic factor. However, for chronic myeloid leukemia (CML), the prognostic role of nm23-H1 gene expression is unknown. The present study investigated the impact of nm23-H1 gene expression on the proliferation and migration of the CML K562 cell line to elucidate the association between nm23-H1 gene expression and CML cell survival. An RNAi lipo-recombinant plasmid of the nm23-H1 gene (pGCsi-nm23-H1) was constructed and transfected into the K562 cells. RT-PCR and western blotting were used to detect nm23-H1 mRNA and protein expression, respectively. The anchorage-independent growth ability of the transfected cells was observed in soft agar culture and the ability of the K562 cells to migrate was determined using a Transwell assay. Following the successful construction and transfection of the pGCsi-nm23-H1 plasmid into the K562 cells, nm23-H1 mRNA and protein expression levels were significantly lower compared with the control group. The stably-transfected pGCsi-nm23-H1 K562 cells exhibited a markedly increased ability to form colonies and the number and sizes of the colonies were significantly increased compared with those of the control. In vitro, the cells migrated through a Matrigel-coated membrane during incubation for 20 h. The Transwell assay revealed that the quantitative number of pGCsi-nm23-H1 K562 cells that migrated into the lower compartment of the invasion chamber was markedly increased compared with the control. In conclusion, nm23-H1 gene expression may inhibit K562 cell proliferation and migration. nm23-H1 may be a cancer suppressor gene and play a significant role in inhibiting the survival of CML cells.

Clinical significance of serum biomarkers in pediatric solid mediastinal and abdominal tumors

Childhood cancer is the leading cause of death by disease among U.S. children between infancy and age 15. Despite successes in treating solid tumors such as Wilms tumor, disappointments in the outcomes of high-risk solid tumors like neuroblastoma have precipitated efforts towards the early and accurate detection of these malignancies. This review summarizes available solid tumor serum biomarkers with a special focus on mediastinal and abdominal cancers in children.

Nm23-h1 indirectly promotes the survival of acute myeloid leukemia blast cells by binding to more mature components of the leukemic clone

Nm23-H1 plays complex roles in the development of diverse cancers including breast carcinoma, high-grade lymphomas, and acute myeloid leukemia (AML). In the case of AML and lymphomas, serum Nm23-H1 protein is elevated with the highest levels correlating with poorest prognosis. A recent study identified that this association is most likely causal in AML and that Nm23-H1 acts as an AML cell survival factor. In this study, we report heterogeneity in the ability of AML samples to bind and respond to Nm23-H1, and we offer evidence that binding is essential for improved survival. Further, we show that the subset of AMLs that bind Nm23-H1 do not do so through the putative Nm23-H1 receptor MUC1*. Although rNm23-H1 promoted the survival of the most primitive blasts within responding AMLs, it was not these cells that actually bound the protein. Instead, rNm23-H1 bound to more mature CD34(lo)/CD34(-) and CD11b(+) cells, revealing an indirect survival benefit of Nm23-H1 on primitive blasts. In support of this finding, the survival of purified blast cells was enhanced by medium conditioned by more mature cells from the clone that had been stimulated by rNm23-H1. Levels of interleukin 1β (IL1β) and IL6 in rNm23-H1 conditioned medium mirrored the potency of the conditioned media to promote blast cell survival. Furthermore, Nm23-H1 expression was significantly associated with IL1β and IL6 expression in primary uncultured AML samples. These findings have implications for the role of Nm23-H1 in AML and its use as a prognostic marker. Additionally, they offer the first evidence of novel cross-talk between cell populations within the tumor clone.

Proteomics of AML1/ETO Target Proteins: AML1–ETO Targets a C/EBP–NM23 Pathway

Introduction

The rational design of targeted therapies for acute myeloid leukemia (AML) requires the discovery of novel protein pathways in the systems biology of a specific AML subtype. We have shown that in the AML subtype with translocation t(8;21), the leukemic fusion protein AML1–ETO inhibits the function of transcription factors PU.1 and C/EBPα via direct protein–protein interaction. In addition, recently using proteomics, we have also shown that the AML subtypes differ in their proteome, interactome, and post-translational modifications.

Methods

We, therefore, hypothesized that the systematic identification of target proteins of AML1–ETO on a global proteome-wide level will lead to novel insights into the systems biology of t(8;21) AML on a post-genomic functional level. Thus, 6 h after inducible expression of AML1–ETO, protein expression changes were identified by two-dimensional gel electrophoresis and subsequent mass spectrometry analysis.

Results

Twenty-eight target proteins of AML1–ETO including prohibitin, NM23, HSP27, and Annexin1 were identified by MALDI-TOF mass spectrometry. AML1–ETO upregulated the differentiation inhibitory factor NM23 protein expression after 6 h, and the NM23 mRNA expression was also elevated in t(8;21) AML patient samples in comparison with normal bone marrow. AML1–ETO inhibited the ability of C/EBP transcription factors to downregulate the NM23 promoter. These data suggest a model in which AML1–ETO inhibits the C/EBP-induced downregulation of the NM23 promoter and thereby increases the protein level of differentiation inhibitory factor NM23.

Conclusions

Proteomic pathway discovery can identify novel functional pathways in AML, such as the AML1–ETO–C/EBP–NM23 pathway, as the main step towards a systems biology and therapy of AML.

Clinical-translational strategies for the elevation of Nm23-H1 metastasis suppressor gene expression

Interruption of the tumor metastatic process is a new, thought provoking molecular target for the treatment of cancer. The Nm23-H1 metastasis suppressor gene stands as a validated molecular target owing to its reduced expression in many aggressive human tumors, and the reduction in metastatic potential in vivo upon re-expression in multiple cell lines. Several compounds have been identified which elevate Nm23-H1 expression in vitro including indomethacin, gamma Linolenic Acid, trichostatin A, 5-aza-deoxycytidine, and high dose medroxyprogesterone acetate. Using a model of lung metastatic colonization by MDA-MB-231 human breast carcinoma cells, we demonstrated that high dose MPA reduced the formation of overt lung metastases by 37-46% and those metastases that formed were statistically smaller. A Phase II clinical trial of high dose MPA, alone or in combination with metronomic chemotherapy has recently opened.

Serum-soluble interleukin-2 receptor (sIL-2R) is an extremely strong prognostic factor for patients with peripheral T-cell lymphoma, unspecified (PTCL-U)

PURPOSE

The aim of this study was to assess the prognostic factors of peripheral T-cell lymphoma, unspecified (PTCL-U).

PATIENTS AND METHODS

We retrospectively analyzed 30 cases fulfilling the criteria of PTCL-U defined by the World Health Organization classification. The patients were treated with 6-8 cycles of a CHOP or THP (pirarubicin)-COP regimen.

RESULTS

A high serum sIL-2R level (> or =2,000 U/ml) at onset was associated with a low complete remission rate. Patients with high sIL-2R had significantly lower survival rates (5 year, 15.1%) than those with low sIL-2R (<2,000 U/ml) (100%) (P < 0.005). Factors associated with worse overall survival in a univariate analysis were high sIL-2R (P < 0.005), high age (>60 years) (P < 0.05), poor performance status (P < 0.01) and poor international prognostic index (P < 0.05). No correlation was observed between sIL-2R and other markers. Multivariate analysis showed that only sIL-2R was a prognostic factor for overall survival (P < 0.01).

CONCLUSION

The results suggest that a high serum sIL-2R level predicts a poor prognosis in PTCL-U.

nm23-H1 protein expression and gene mutation in 150 patients with non-Hodgkin's lymphomas

The metastasis-suppressing role of the nm23 gene in the metastatic spread of malignant tumor is still debated. We examined the nm23-H1 protein expression and gene mutation in non-Hodgkin's lymphomas to compare with the clinicopathologic parameters. The expression of nm23-H1 protein was immunohistochemically examined in 150 cases of non-Hodgkin's lymphomas; 85 diffuse large B cell lymphomas (DL-BCL), 18 marginal zone B cell lymphomas (MZL), 3 mantle cell lymphomas, 25 peripheral T cell lymphomas, not otherwise specified (TCLNOS), and 19 NK/T cell lymphomas (NK/T). Eighty-one cases (58 DLBCL, 6 MZL, 4 TCLNOS, and 13 NK/T) were studied for nm23-H1 gene mutation in exon 1 to 5. The high expression of nm23-H1 protein was associated with the high IPI score (p=0.019) and the low survival rate of the patients (p=0.0039). The gene mutation of nm23-H1 was detected in 10.3% of DLBCL and 30.7% of NK/T; but none in MZL and TCLNOS. The mutation was found in exon 1 in 5 cases, exon 2 in two cases, exon 4 in one case and both exon 1 and 2 in two cases. Our results suggest that the expression of nm23-H1 protein can be used as a poor prognostic marker in non-Hodgkin's lymphomas, and the mutational change of gene may operate in the lymphomagenesis.

Metastasis suppressor gene Raf kinase inhibitor protein (RKIP) is a novel prognostic marker in prostate cancer

BACKGROUND

Diminished expression of Raf kinase inhibitor protein (RKIP), an inhibitor of the Raf signaling cascade, promotes prostate cancer (PCa) metastasis in a murine model, suggesting that it is a metastasis suppressor gene. However, the prognostic significance of RKIP expression and its association with metastasis in PCa patients is unknown.

METHODS

To investigate RKIP protein expression is a prognostic marker in PCa we performed immunohistochemical staining for RKIP expression in tissue microarrays consisting of 758 non-neoplastic prostate tissues, primary tumors and metastases from 134 PCa patients. The Cox proportional-hazards model was used to adjust for covariates including Gleason score, tumor volume, tumor weight, clinical stage, digital rectal exam findings, serum PSA level and surgical margins.

RESULTS

RKIP expression was low in approximately 5%, 48%, and 89% of non-neoplastic prostate, primary tumors and metastases, respectively. Low RKIP expression in primary tumors was a strong positive predictive factor for PCa recurrence based on PSA levels. In patients whose primary tumors expressed high RKIP levels, the 7-year PSA recurrence rate was <10%; whereas in patients with tumors with low RKIP expression the recurrence rate was 50% (P<0.001). Multivariate analysis revealed RKIP was an independent prognostic factor (P<0.001).

CONCLUSION

In contrast to increased expression of pro-tumorigenic genes, these results demonstrate decreased protein expression of a gene, for example, RKIP, can serve as a prognostic marker in PCa patients.

Translational control of putative protooncogene Nm23-M2 by cytokines via phosphoinositide 3-kinase signaling

The expansion and differentiation of hematopoietic progenitors is regulated by cytokine and growth factor signaling. To examine how signal transduction controls the gene expression program required for progenitor expansion, we screened ATLAS filters with polysome-associated mRNA derived from erythroid progenitors stimulated with erythropoietin and/or stem cell factor. The putative proto-oncogene nucleoside diphosphate kinase B (ndpk-B or nm23-M2) was identified as an erythropoietin and stem cell factor target gene. Factor-induced expression of nm23-M2 was regulated specifically at the level of polysome association by a phosphoinositide 3-kinase-dependent mechanism. Identification of the transcription initiation site revealed that nm23-M2 mRNA starts with a terminal oligopyrimidine sequence, which is known to render mRNA translation dependent on mitogenic factors. Recently, the nm23-M2 locus was identified as a common leukemia retrovirus integration site, suggesting that it plays a role in leukemia development. The expression of Nm23 from a retroviral vector in the absence of its 5'-untranslated region caused constitutive polysome association of nm23-M2. Polysome-association and protein expression of endogenous nm23-M2 declined during differentiation of erythroid progenitors, suggesting a role for Nm23-M2 in progenitor expansion. Taken together, nm23-m2 exemplifies that cytokine-dependent control of translation initiation is an important mechanism of gene expression regulation.

Clinical Significance of Intracytoplasmic nm23-H1 Expression in Diffuse Large B-Cell Lymphoma

PURPOSE

Recently, we established an ELISA technique for measuring nm23-H1 protein in serum and found that the serum nm23-H1 level is a potential prognostic factor for patients with non-Hodgkin's lymphoma.

EXPERIMENTAL DESIGN

We used immunohistochemistry to examine the expression of nm23-H1 by the lymphoma cells in patients with diffuse large B-cell lymphoma (DLBCL).

RESULTS

By analyzing a consecutive series of 172 untreated DLBCL patients, we found that 100 (58.1%) were strongly positive. The cytoplasmic nm23 expression in lymphoma cells correlated significantly with the serum nm23-H1 level. There was a significant correlation between patients with cytoplasmic nm23-positive lymphoma and those with performance status 2-4, stage III/IV, bulky mass, B symptoms, elevated serum level of soluble interleukin 2 receptor, and elevated serum level of C-reactive protein. Overall and progression-free survival rates were significantly lower in patients with nm23-H1-positive lymphomas than in those with nm23-H1-negative lymphomas. Similar difference was seen between patients with high and low serum levels of nm23-H1. Thus, the correlation between presence or absence of cytoplasmic nm23-H1 expression and serum nm23-H1 levels suggests that serum nm23-H1 is produced directly by lymphoma cells.

CONCLUSION

We suggest that nm23-H1 expression is a prognostic factor for DLBCL, and that it is as important as serum nm23-H1, both of which are useful for planning a treatment strategy.

Expression of nm23-H1 is associated with poor prognosis in peripheral T-cell lymphoma

We have reported previously that the serum nm23-H1 level is a prognostic factor for non-Hodgkin's lymphoma. In this study, we examined nm23-H1 expression in T- and natural killer (NK)-cell lymphoma in order to evaluate whether lymphoma cells produce the protein. The clinical significance of the cytotoxic molecules, T-cell intracellular antigen-1 (TIA-1) and granzyme B and nm23-H1 expression were also examined. Expression of nm23-H1, TIA-1, or granzyme B was examined by immunohistochemistry in 137 previously untreated lymphoma patients. The relationship between the results and clinical outcome was examined in 81 patients with angioimmunoblastic T-cell lymphoma, anaplastic large cell lymphoma, or peripheral T-cell lymphoma, unspecified. The neoplastic cells of some lymphomas produced nm23-H1 and the expression rates of nm-23-H1, TIA-1 and granzyme B were 36.5%, 78.8% and 32.8% respectively. The nm23-H1-positive or TIA-1-positive groups had significantly shorter overall and disease-free survivals. Multivariate analysis confirmed nm23-H1 expression to be an independent prognostic factor. The nm23-H1 protein can be an important prognostic factor in the lymphomas studied here. New treatments that target nm23 overexpression could be developed as a result of nm23-HI production by lymphoma cells.

Physiological and pathological relevance of extracellular NM23/NDP kinases

The NM23 gene is overexpressed in many hematological malignancies and other neoplasms. Some tumor cell lines that overexpress NM23 secrete this protein into extracellular environment. In this study, we found that the serum concentration of NM23-H1 protein was significantly higher in patients with various hematological malignancies. The serum level of NM23-H1 protein was clinically useful as a prognostic factor in malignant lymphoma and acute myelogeneous leukemia (AML). The level of NM23-H1 protein in all of the normal serum samples examined was lower than 10 ng/mL, while those in the tumors varied from about 0 to 1000 ng/mL. Exogenously added NM23-H1 protein did not affect the growth or survival of various leukemia and lymphoma cell lines. However, NM23-H1 protein inhibited the survival of adherent normal peripheral blood mononuclear cells (PBMNC) at 100-1000 ng/mL, and slightly stimulated the survival of nonadherent PBMNC. These results suggest that the effect of NM23-H1 protein on normal PBMNC may be associated with a poor prognosis in hematological malignancies.