NME6 is a phosphotransfer-inactive, monomeric NME/NDPK family member and functions in complexes at the interface of mitochondrial inner membrane and matrix

Background

NME6 is a member of the nucleoside diphosphate kinase (NDPK/NME/Nm23) family which has key roles in nucleotide homeostasis, signal transduction, membrane remodeling and metastasis suppression. The well-studied NME1-NME4 proteins are hexameric and catalyze, via a phospho-histidine intermediate, the transfer of the terminal phosphate from (d)NTPs to (d)NDPs (NDP kinase) or proteins (protein histidine kinase). For the NME6, a gene/protein that emerged early in eukaryotic evolution, only scarce and partially inconsistent data are available. Here we aim to clarify and extend our knowledge on the human NME6.

Results

We show that NME6 is mostly expressed as a 186 amino acid protein, but that a second albeit much less abundant isoform exists. The recombinant NME6 remains monomeric, and does not assemble into homo-oligomers or hetero-oligomers with NME1-NME4. Consequently, NME6 is unable to catalyze phosphotransfer: it does not generate the phospho-histidine intermediate, and no NDPK activity can be detected. In cells, we could resolve and extend existing contradictory reports by localizing NME6 within mitochondria, largely associated with the mitochondrial inner membrane and matrix space. Overexpressing NME6 reduces ADP-stimulated mitochondrial respiration and complex III abundance, thus linking NME6 to dysfunctional oxidative phosphorylation. However, it did not alter mitochondrial membrane potential, mass, or network characteristics. Our screen for NME6 protein partners revealed its association with NME4 and OPA1, but a direct interaction was observed only with RCC1L, a protein involved in mitochondrial ribosome assembly and mitochondrial translation, and identified as essential for oxidative phosphorylation.

Conclusions

NME6, RCC1L and mitoribosomes localize together at the inner membrane/matrix space where NME6, in concert with RCC1L, may be involved in regulation of the mitochondrial translation of essential oxidative phosphorylation subunits. Our findings suggest new functions for NME6, independent of the classical phosphotransfer activity associated with NME proteins.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13578-021-00707-0.

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.

Correlation between ultrasonic features and expression levels of C-erbB-2, VEGF and nm23 in breast cancer

Breast cancer is one of the most common female malignancies in clinical practice, which ranks number one in terms of its high incidence. We investigated the relevance of ultrasonic features of breast cancer and expression levels of C-erbB-2, vascular endothelial growth factor (VEGF) and nm23 and its clinical significance. A total of 76 patients with breast cancer were recruited who were admitted to The Affiliated Hospital of Qingdao University from January, 2016 to August, 2017. All patients underwent color Doppler ultrasonic imaging, and expression levels of C-erbB-2, VEGF and nm23 in their tumor tissues were measured by immunohistochemistry. The ultrasonic features were evaluated and compared with the expression levels of C-erbB-2, VEGF and nm23 for each patient. Ultrasonography showed a tumor mass with spiculated margins, abnormal vasculature, and a diameter no less than 3 cm, as well as lymph node metastasis. The above signs were associated with high expression of C-erbB-2, VEGF and nm23 (p<0.05), but calcification was not associated with high expression of these biomarkers (p>0.05). For patients with highly expressed C-erbB-2 and VEGF, the time to peak (TTP) of the time-intensity curve obtained by contrast enhanced ultrasound was shorter, while the peak intensity (PI) was higher. On the contrary, for patients with highly expressed nm23, the TTP was apparently longer, while the PI was lower (p<0.05). The ultrasonic features of breast cancer were relevant to the expression levels of C-erbB-2, VEGF and nm23. Thus, the expression levels of C-erbB-2, VEGF and nm23 were predictable indirectly according to the ultrasonic features of the patient, which can be used as a reference for breast cancer treatment and prognosis prediction.

Hierarchical investigating the predictive value of p53, COX2, EGFR, nm23 in the post-operative patients with colorectal carcinoma

The aim of this study was to evaluate the correlations between p53, COX2, EGFR, nm23 expression and the progression free survival (PFS) of post-operative patients with colorectal carcinoma. Immunohistochemistry was used to detect the expression of p53, COX2, EGFR and nm23 in 459 specimens from colorectal carcinoma patients. Kaplan-Meier estimates, Cox proportional hazard regression analyses and hierarchical analyses were performed on the collected data. Kaplan-Meier estimates analysis suggested that EGFR expression was as a negative predictor, the median PFS of patients with EGFR high expression was 21.73 months, and the median PFS of patients with low EGFR expression was 57.83 months (χ²=20.880, P<0.001); nm23 expression was positive predictive factor for the prognosis of patients with colorectal carcinoma, the median PFS of patients with high nm23 expression was 37.77 months, and the median PFS was 21.47 months in the patients with low nm23 expression (χ²=7.364, P=0.007). Cox regression analysis revealed that comparing with the patients with low expression of EGFR, the patients with high EGFR expression were at higher risk of tumor progression (HR=1.667, P=0.004); Comparing with the patients with high nm23 expression, the patients with nm23 low expression had a higher risk of tumor progression (HR=0.412, P<0.001); and the risk of tumor progression was higher in the patients with high EGFR expression and low nm23 expression (HR=0.245, P<0.001). Hierarchical analysis showed that EGFR expression mainly correlates with the PFS of TNM stage I-II colorectal cancer patients, the median PFS was 33.53 months in the TNM stage I-II colorectal cancer patients with high EGFR expression patients; The median PFS of the TNM stage I-II colorectal cancer patients with low EGFR expression was 70.43 months (χ²=9.530, P=0.002); The median PFS was 19.2 months in the TNM stage III-IV colorectal cancer patients with high expression EGFR, the PFS of the TNM stage III-IV colorectal cancer patients with low EGFR expression was 37.87 months (χ²=7.97, P=0.005). nm23 expression mainly correlates with the PFS of TNM stage III-IV colorecatal cancer patients. The median PFS was 47.27 months in TNM stage I-II colorectal cancer patients with nm23 high expression, the median PFS was 48.85 months in TNM stage I-II colorectal cancer patients with low nm23 expression (χ²=0.101, P=0.750); The median PFS was 28.8 months in TNM stage III-IV colorectal cancer patients with nm23 high expression, the median PFS was 14.7 months in TNM stage III-IV colorectal cancer patients with low nm23 expression (χ²=13.213, P<0.001). EGFR is mainly a predictive factor for the prognosis of post-operative patients with TNM stage I-II colorectal cancer, and nm23 is important for predicting the prognosis of patients with stage III-IV, and EGFR and nm23 could be as predictor of combination.

Roles of KAI1 and nm23 in lymphangiogenesis and lymph metastasis of laryngeal squamous cell carcinoma

Background

Lymphatic metastasis contributes to the poor prognosis of laryngeal squamous cell carcinoma (LSCC). This study aimed to investigate the roles of two metastasis suppressor genes, KAI1 and nm23, in lymphangiogenesis and lymph metastasis of LSCC.

Methods

A total of 45 LSCC patients were enrolled in this study. The positive expression rates of KAI1 and nm23 protein were detected via immunohistochemistry in 45 LSCC and 22 normal laryngeal mucosa adjacent to LSCC. Micro-lymphatic vessel density (MLVD) was detected via immunohistochemistry with the specific antibody D2-40. Associations between KAI1 and nm23 expression and clinical characteristics of LSCC were then evaluated.

Results

The positive expression rates of KAI1 and nm23 were significantly lower in LSCC than normal laryngeal mucosa (P < 0.05). Significantly lower positive rates of KAI1 and nm23 were found in LSCC with lymphatic metastasis than those without lymphatic metastasis (P < 0.05), whereas MLVD was negatively correlated with the expression of KAI1 and nm23 (P < 0.05). However, no significant associations were found between KAI1 and nm23 expression and clinical characteristics of LSCC (sex, age, disease position, differentiation, and T-stage).

Conclusions

Both KAI1 and nm23 can inhibit lymphangiogenesis and lymphatic metastasis in LSCC.

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.

Clinical significance of expression of p85a, nm23 and MMP-2 in primary colorectal cancer and lymph node metastasis

AIM: To detect the expression of p85a, nm23 and matrix metalloproteinase-2 (MMP-2) in primary colorectal cancer and lymph node metastasis, and to discuss the role and significance of p85a, nm23 and MMP-2 in colorectal cancer metastasis.

METHODS: Two hundred and forty-three colorectal cancer patients were divided into two groups: patients with cervical lymph node metastasis and those without. Primary tumor samples from patients without cervical lymph node metastasis (n = 51) and those with lymph node metastasis (n = 192), cervical lymph node metastasis samples (n = 192), and normal colorectal tissue samples from normal controls (n = 243) were collected. Immunohistochemistry was used to detect the expression of p85a, nm23 and MMP-2 in the above samples. The correlations between expression of p85a, nm23 and MMP-2 and clinicopathological and prognostic factors of colorectal cancer were analyzed.

RESULTS: The positive expression rates of p85a and MMP-2 in primary tumor and lymph node metastasis samples from patients with lymph node metastasis were significantly higher than those in primary tumors from patients without cervical lymph node metastasis and normal colorectal tissue samples. The expression of nm23 in the metastasis was significantly lower than those in the other groups. In metastatic cancer, the expression of p85a and nm23 had a negative correlation (P < 0.05), and p85a and MMP-2 had a positive correlation (P < 0.05). According to survival analysis, p85a, nm23 and MMP-2 were independent factors for the prognosis of colorectal cancer. The cases with higher p85a and lower nm23 or with both higher p85a and MMP-2 had shorter lifetime.

CONCLUSION: In the process of colorectal cancer metastasis, p85a can enhance the expression of MMP-2 and restrain the expression of nm23. They all play an important role in colorectal metastasis, and all of them are prognostic factors for colorectal cancer.

Significance of expression of p53 and nm23 in mucous adenocarcinoma of the rectum

AIM: To investigate the clinical significance of expression of p53 and nm23 in mucous adenocarcinoma (MUC) of the rectum.

METHODS: The expression of p53 and nm23 in 37 cases of MUC and 261 cases of non-MUC of the rectum was detected by using immunohistochemical streptavidin-peroxidase method.

RESULTS: The positive rates of high p53 and nm23 expression in MUC were significantly lower than those in non-MUC (16.2% vs 35.6%, 13.5% vs 29.9%, P < 0.05 for both). The expression of p53 and nm23 was not correlated with tumor size, gender, invasion depth, 1ymph node metastasis or TNM stage (P > 0.05 for all). Nm23 expression was not related to p53 expression.

CONCLUSION: The expression of p53 and nm23 is low in rectal MUC, and they may have no significant role in the development and progression of this malignancy.

Significance of expression of p53, nm23 and Ki-67 in esophageal neuroendocrine carcinoma

AIM: To investigate the significance of expression of p53, nm23 and Ki-67 in esophageal neuroendocrine carcinoma.

METHODS: The expression of p53, nm23 and Ki-67 in 42 esophageal neuroendocrine carcinoma specimens was assessed by immunohistochemistry.

RESULTS: The positive expression rate of p53 in esophageal neuroendocrine carcinoma was 97.62%, and the high expression rate was 90.48%; the positive expression rate of nm23 was 57.14%, and the high expression rate was 33.33%; the positive expression rate of Ki-67 was 97.62%, and the high expression rate was 61.90%. p53 and Ki-67 were highly expressed in esophageal neuroendocrine carcinoma. The expression of p53 and Ki-67 in esophageal neuroendocrine carcinoma had no significant association with age, sex, tumor site, pathological classification, depth of invasion or lymphatic metastasis (P > 0.05). The expression of nm23 had no significant association with age, sex, tumor site, or pathological classification (P > 0.05), but was significantly associated with depth of invasion and lymphatic metastasis (P < 0.05).

CONCLUSION: The biological behavior and immunophenotype of esophageal neuroendocrine carcinoma are different from those of other malignant tumors. High expression of p53 and Ki-67 has a close relationship with poor prognosis. The examination of p53, Ki-67 and nm23 expression may be helpful to judge prognosis of esophageal neuroendocrine carcinoma.

Altered gene and protein expression by Nm23-H1 in metastasis suppression

Metastasis suppressor genes (MSG) are characterized by their ability to inhibit the formation of metastasis, while not affecting the growth of the primary tumor in vivo. Nm23-H1, the first MSG to be characterized, has been shown to alter both gene and protein expression in cancer cells. Recently, microarray expression profiling revealed that Nm23-H1 downregulated EDG2, which encodes for a lysophosphatidic acid (LPA) receptor. Reintroduction of EDG2 into cells that express Nm23-H1 overcame the metastasis suppressive ability of Nm23-H1 in both in vivo pulmonary colonization and spontaneous metastasis assays. In addition, isotope capture affinity tag (ICAT) proteomic analysis was performed to identify differentially expressed proteins not accounted for by microarray analysis. ICAT identified several differentially regulated proteins, including GEMIN5, a protein involved in differential mRNA splicing. The contribution of alternative mRNA splicing to cancer and cancer metastasis is poorly defined. It is possible that Nm23-H1, through the regulation of RNA processing proteins, may play a role in proteome stability.

Developmental function of Nm23/awd: a mediator of endocytosis

The metastasis suppressor gene Nm23 is highly conserved from yeast to human, implicating a critical developmental function. Studies in cultured mammalian cells have identified several potential functions, but many have not been directly verified in vivo. Here, we summarize the studies on the Drosophila homolog of the Nm23 gene, named a bnormal w ing d iscs (awd), which shares 78% amino acid identity with the human Nm23-H1 and H2 isoforms. These studies confirmed that awd gene encodes a nucleoside diphosphate kinase, and provided strong evidence of a role for awd in regulating cell differentiation and motility via regulation of growth factor receptor signaling. The latter function is mainly mediated by control of endocytosis. This review provides a historical account of the discovery and subsequent analyses of the awd gene. We will also discuss the possible molecular function of the Awd protein that underlies the endocytic function.

Metastasis suppressors and their roles in breast carcinoma

Metastasis remains the most deadly aspect of cancer and still evades direct treatment. Clinically and experimentally, primary tumor development and metastasis are distinct processes-locally growing tumors can progress without the development of metastases. The discovery of endogenous molecules that exclusively inhibit metastasis suggests that metastasis is an amenable therapeutic target. By definition, metastasis suppressors inhibit metastasis without inhibiting tumorigenicity and are thus distinct from tumor suppressors. As the biology underlying functional mechanisms of metastasis suppressors becomes clearer, it is evident that metastasis suppressors could be harnessed as direct drug targets, prognostic markers, and to understand the fundamental biology of the metastatic process. Metastasis suppressors vary widely in their cellular localization: they are found in every cellular compartment and some are secreted. In general, metastasis suppressors appear to regulate selectively how cells respond to exogenous signals, by affecting signaling cascades which regulate downstream gene expression. This review briefly summarizes current functional and biochemical data on metastasis suppressors implicated in breast cancer. We also present a schematic integrating known mechanisms for these metastasis suppressors highlighting potential targets for therapeutic intervention.

Effects of body-resistance strengthening and tumor-suppressing granules on immune adhesion function of red blood cells and expression of metastasis protein CD44 in tumor cells of patients with esophageal carcinoma

AIM: To investigate the effects of Fuzheng Yiliu granules (body-resistance strengthening and tumor-suppressing granules) in patients with esophageal carcinoma.

METHODS: We compared the immune adherent properties of red blood cells (RBCs), the expression of metastasis protein CD44, and the metastasis inhibition factor nm23, in esophageal carcinoma tumor cells of patients before and after radiotherapy in the presence and absence of orally administered Fuzheng Yiliu granules. Sixty-three hospitalized patients with esophageal carcinoma were treated with standard radiotherapy and randomly divided into treatment group (n = 30) treated with both radiotherapy and Fuzheng Yiliu granules and control group (n = 33) given radiotherapy only. Blood samples and tumor tissue were obtained before and after 21 d of treatment. The rosette rates for complement receptor type 3b (C3bRR) and immune complex receptor (ICRR) on RBCs were measured by erythrocyte immunological methods. Expression of CD44 and nm23 in tumor tissue sections was determined by immunohistochemical staining with monoclonal antibodies CD44v6 ad nm23H-1, respectively.

RESULTS: The positivity of RBC-C3bRR before and after 21 d of treatment increased from 7.78% ± 1.59% to 10.03% ± 2.01% in the double treatment group, while it changed only slightly from 7.18% ± 1.29% to 7.46% ± 1.12% in the radiotherapy group. The positive rate for RBC-ICRR decreased from 37.68% ± 2.51% to 22.55% ± 1.65% after the double treatment, and from 37.28% ± 2.41% to 24.69% ± 1.91% in radiotherapy group at the same time points. The difference in erythrocyte immune adherent function between the two groups was significant (P < 0.01, t-test). The CD44⁺-cases were reduced from 21 (70.00%) to 12 (40.00%) after treatment with Fuzheng Yiliu granules, whereas the CD44⁺-cases (69.70%) in the radiotherapy group remained unchanged. The difference between the treatment (40.00%) and control (69.70%) groups was significant (P < 0.05). Although the nm23⁺-cases were increased from 4 (13.33%) to 6 (20.00%) in the double treatment group and from 6 (18.18%) to 7 (21.21%) in the radiotherapy group, the difference was not significant (P > 0.05).

CONCLUSION: Fuzheng Yiliu granules enhance the immune adhesion function of RBCs and reduce the number of CD44⁺-cells in esophageal carcinoma patients, suggesting a potential role of these Chinese herbals in suppression of invasion and metastasis of malignant cells. However, this anti-metastatic effect has yet to be validated in vivo.

Expressions and significances of Caveolin-1, nm23 and matrix metalloproteinase -2 in gastric carcinomas

AIM: To investigate the protein expression of Caveolin-1, nm23 and matrix metalloproteinase-2 (MMP-2) in normal gastric mucosa, gastric atypical hyperplasia and gastric carcinoma tissues.

METHODS: S-P immunohistochemical method was used to detect the expression of Caveolin-1, nm23 and MMP-2 proteins in normal gastric mucosa (n = 25), gastric atypical hyperplasia (n = 65), and gastric carcinomas (n = 71).

RESULTS: Caveolin-1 and nm23 expression showed a decreasing tendency in normal gastric mucosa, atypical hyperplasia and gastric cancer tissues ordinarily, and there were statistical differences between groups (χ² = 106.303, P < 0.05; χ² = 64.254, P < 0.05). However, MMP-2 expression exhibited a increasing tendency (χ² = 35.247, P < 0.05). Fisher's exact test demonstrated that the expression of Caveolin-1, nm23 and MMP-2 protein were significantly different between the cases with different invasion depths or lymph node metastases (P < 0.05), but not between the cases with different ages, sex and vessel invasions (P > 0.05). Spearman rank correlation analysis indicated that the expression of Caveolin-1 was positively correlated with that of nm23 (r = 0.957, P < 0.05) , but negatively correlated with that of MMP-2 (r = -0.975, P < 0.05). Furthermore, there was a negative correlation between nm23 and MMP-2 expression (r = -0.987, P < 0.05).

CONCLUSION: The absent expression of Caveolin-1 and nm23 together with over-expression of MMP-2 may be one of the important causes for the onset, development and progression of gastric carcinoma. Caveolin-1 may serve as a tumor suppressor gene.

Immunohistochemical expression of carcinoembryonic antigen, P53, nm23, Ki-67, multidrug resistance-associated protein and their correlations with the clinicopathology in colorectal carcinoma

AIM: To investigate the mechanism of cyclooxygenase-2 (COX-2), basic fibroblast growth factor (bFGF) in the carcinogenesis of colorectal carcinoma and adenoma.

METHODS: The expression of CEA, P53, nm23, Ki-67 and MRP protein were detected by SP immunohistochemistry in colorectal carcinoma (n = 73) admitted from January 2003 to July 2006, and their clinical data and follow-up documents were analyzed retrospectively.

RESULTS: The positive rates of CEA, P53, nm23, Ki-67 and MRP protein expression in colorectal cancer were 82.2%, 68.5%, 75.3%, 84.9% and 64.4%, respectively. CEA and MRP expression had no correlations with the patients'ages, sex, tumor size or location and differentiation types of tumor, depth of invasion and lymph node metastasis, while P53, Ki-67 and nm23 expression were significantly correlated with the depth of invasion and lymph node metastasis. The positive rates of P53 and Ki-67 expression was significantly higher in Dukes C, D stages than those in Dukes A, B stages (82.8% vs 59.1%, P < 0.05; 100% vs 75.0%, P < 0.05), while the positive rate of nm23 expression was markedly lower (58.6% vs 86.4%, P < 0.05). The expression of CEA had a negative correlations with that of nm23 (r = -0.296, P = 0.011) in colorectal carcinoma. However, the expression of P53 had a positive correlations with that of Ki-67 (r = 0.308, P = 0.008). P53, Ki-67 and nm23 expression were significantly related to the prognosis. The positive rate of nm23 expression was notably higher in patients survived over or equal to 3 years than that in ones survived less than 3 years (92.9% vs 71.2%, P < 0.05), but the positive rates of P53 and Ki-67 expression were just in the opposite situation (42.9% vs 74.6%, P < 0.05; 64.3% vs 89.8%, P < 0.05).

CONCLUSION: P53, Ki-67 and nm23 were significantly correlated with the invasion, metastasis and prognosis of colorectal carcinoma. CEA may be a stimulative factor in the invasion and metastasis of colorectal cancer and MRP-induced drug resistance may be relatively independent. CEA, P53, nm23 and Ki-67 can serve as effective markers ini reflecting the invasion, metastasis and prognosis of colorectal carcinoma.

Expression of KAI1, nm23 and P53 in Gastric Carcinoma and Their Clinical Significances

AIM: To investigate the expression of KAI1, nm23 and P53 protein as well as their significances in the development of gastric carcinoma.

METHODS: The expression of KAI1, nm23 and P53 protein were detected by SP immunohistochemistry in gastric atypical hyperplasia (n = 65), gastric carcinoma (n = 74) and normal gastric tissues (n = 22).

RESULTS: The positive rates of KAI1 and nm23 protein expression were decreased with the malignancy of gastric tissues, and there were significantly differences between normal gastric tissues, atypical hyperplasia and carcinoma (KAI1: χ² = 20.885, P < 0.001; nm23: χ² = 29.133, P < 0.05), while the positive rate of P53 protein expression was in the opposite tendency (χ² = 21.954, P < 0.001). The expression of KAI1, nm23 and P53 protein were notably correlated with the depth of invasion, lymph nodes metastasis and vessel invasion (χ² = 20.885, P < 0.001; χ² = 29.133, P < 0.05; χ² = 21.954, P < 0.001), but they were not correlated with the age and gender of patients. Besides, the expression of KAI1 was positively related to that of nm23 (r = 0.859, P < 0.05), but negatively related to that of P53 (r = -0.859, P < 0.05). Negative correlation was also found between the expression of nm23 and P53 (r = -0.874, P < 0.05)

CONCLUSION: Loss expression of KAI1 and nm23 and over-expression of P53 may play important roles in the progression and lymph node metastasis of gastric carcinoma.

Stathmin in Cell Proliferation and Cancer Progression

The phosphoprotein stathmin exerts profound influences on cell proliferation, differentiation and in cell motility. These phenotypic features are displayed in response to specific signals imparted to the cell by biological response modifiers. Stathmin functions as a focal point in co-ordinating and directing the cellular signals into specific and defined pathways. Two biological features that characterise cancer are the deregulation of cell proliferation leading to tumour growth and invasive behaviour. Stathmin is up-regulated in many neoplasms and the modulation of its expression correlates with invasion and metastasis and highly proliferating normal tissues. The integrity of the transduction of extracellular signals is essential for the normal functioning of the cellular machinery in cell differentiation, morphogenesis and cell proliferation, apoptosis, growth and senescence. Stathmin mediates these pathways of signalling. Stathmin has been implicated in both G₁-S and G₂-M checkpoint control of cell cycle progression by influencing the dynamics of microtubule formation and progression of the cell cycle. Stathmin appears to exert its regulatory effects at both G₁-S and G₂-M checkpoints by interacting with other cell cycle control proteins such as p53 and rb and with cancer metastasis promoting or inhibiting genes as well as other proteins such as heat shock proteins. Stathmin co-ordinates the signalling by extracellular matrix proteins, and defines intercellular adhesion and cell motility. Therefore, the deregulation of stathmin function would have profound implications in the pathogenesis and progression of cancer.

Expression of p53 and nm23 gene protein in sex-difference analyzing among gastric carcinoma traditional Chinese medicine classifications of syndrome

AIM: To analyze sex-difference in p53 and nm23 gene protein expression, TNM staging classification, lymph node metastasis, and distance metastasis among different categories of gastric carcinoma according to traditional Chinese medicine (TCM) classification, and to provide scientific basis for probing the relationship between the essence of gastric carcinoma and TCM syndrome classification.

METHODS: We classified gastric carcinoma patiets into six groups according to TCM classification of syndrome criteria. Specimens taken after operation were analysed for p53 and nm23 gene protein expression by immunohistochemistry assay. Then TNM staging, lymph node metastasis, and distance metastasis were analyzed.

RESULTS: There is no significent difference among six groups after statistical analysis in TNM staging, lymph node metastasis, and distant metastasis. There is statistical difference between the two TCM classification of syndrome groups of stagnation of phlegm-damp and Yin-insufficiency due to stomach-heat in different sexes (P<0.05). The lymph node metastasis in female patients is more than that in male ones in the group of stagnation of phlegm-damp; while in the group of Yin-insufficiency due to stomach-heat, the result is opposite (P>0.05). p53 gene protein expression in female patients has statistical difference among six TCM Classification of syndrome groups (P = 0.03). p53 gene protein expression in male patients is higher than that in female ones (P = 0.01). The protein expression of p53 and nm23 in female patients is higher than that in male patients (P<0.05).

CONCLUSION: The protein expression of p53 (in groups of stagnation of phlegm-damp and Yin-insufficiency due to stomach-heat) and nm23 (in group of Yin-insufficiency due to stomach-heat) has statistical difference between male and female patients. The sex difference in p53 and nm23 expression also has statistical difference in lymph node metastasis and distance metastasis.

The predictive value of vascular endothelial growth factor and nm23 for the diagnosis of occult metastasis in non-small cell lung cancer

We assessed the association of vascular endothelial growth factor (VEGF) and nm23 expression with occult micrometastasis in lung cancer. As destination sites for micrometastasis, we scrutinized lymph node (LN) and bone marrow (BM) specimens. For LN, 122 stage I patients who had received curative operations were studied. As regards BM, 203 patients in stage I - IV who underwent operations were registered. Immunohistochemical anti-cytokeratin staining was used to detect microdissemination of cancer cells. The VEGF and the nm23 expression at the primary sites were immunohistochemically studied in 285 cases in total. The percentages of the patients with microdissemination were 28.7% for LN and 42.4% for BM. The outcome for the patients with LN or BM microdissemination was significantly worse than that for patients without it. The increased VEGF and the decreased nm23 expression within primary tumors were significantly associated with LN and BM microdissemination. The results indicate possible value of using these biological markers to predict the risk of systemic micrometastasis in non-small cell lung cancer.

Downregulation of intracellular nm23-H1 prevents cisplatin-induced DNA damage in oesophageal cancer cells: possible association with Na(+), K(+)-ATPase

Previously, we showed that expression of nm23-H1 is associated inversely with sensitivity to cisplatin in human oesophageal squamous cell carcinoma (OSCC). The present study was undertaken to investigate the association of nm23-H1 expression with cisplatin-induced DNA damage in OSCC using antisense nm23-H1 transfectants. YES-2/AS-12, an antisense nm23-H1-transfected OSCC cell line, showed significantly reduced expression of intracellular nm23-H1 protein compared with that in parental YES-2 cells and YES-2/Neo transfectants. Surface expression of nm23-H1 protein was not observed in any of the three cell lines. PCR analysis for DNA damage demonstrated that YES-2/AS-12 cells were more resistant to nuclear and mitochondrial DNA damage by cisplatin than were YES-2/Neo cells. In addition, mitochondrial membrane potentials and DNA fragmentation assays confirmed that YES-2/AS-12 was more resistant than YES-2/Neo to apoptosis induced by cisplatin. In contrast, YES-2/AS-12 was more sensitive to ouabain, a selective inhibitor of Na(+), K(+)-ATPase, than YES-2 and YES-2/Neo. Pre-treatment with ouabain resulted in no differences in cisplatin sensitivity between the three cell lines examined. Intracellular platinum level in YES-2/AS-12 was significantly lower than that in YES-2 and YES-2/Neo following incubation with cisplatin, whereas ouabain pre-treatment resulted in no differences in intracellular platinum accumulations between the three cell lines. Our data support the conclusion that reduced expression of intracellular nm23-H1 in OSCC cells is associated with cisplatin resistance via the prevention of both nuclear and mitochondrial DNA damage and suggest that it may be related to Na(+), K(+)-ATPase activity, which is responsible for intracellular cisplatin accumulation.

nm23-H1 expression defines a high-risk subpopulation of patients with early-stage epithelial ovarian carcinoma

The role of the nm23 gene in human ovarian cancer is still controversial. We studied the expression of the nm23-H1 gene in 247 human epithelial ovarian carcinomas. The patients were followed-up until their death, or for a minimum of 5 years if they survived. The expression of the gene was studied by means of immunohistochemistry and a semiquantitative scoring system considering the staining intensity and the number of reactive tumour cells. Patients carrying tumours with higher expression scores (4-6 on a scale from 0 to 6) had a significantly lower survival (P = 0.01) than the rest. Further stratified statistical analysis revealed that this effect was mainly attributable to the subgroup of patients with early-stage (I and II), well- and moderately differentiated tumours. In fact, a multivariate analysis carried out for this subset of patients showed nm23-overexpression to be the only significant independent predictor of an ominous prognosis. The association of nm23-overexpression with a worse prognosis was most probably not due to mutation of the nm23 gene, since mutational analysis in 60 tumours by means of single-strand conformational polymorphism and direct sequencing disclosed only one mutation, which was located outside the open reading frame. Our results seem to indicate that nm23 expression is associated with a significantly worse prognosis in early-stage, well-differentiated epithelial ovarian carcinoma, a finding with important clinical implications, considering that many patients with ovarian cancers showing these features do not undergo any further treatment beyond surgical staging. If confirmed, they could help in tailoring the treatment of these patients in the future.

Molecular biology of breast cancer metastasis. Genetic regulation of human breast carcinoma metastasis

The present is an overview of recent data that describes the genetic underpinnings of the suppression of cancer metastasis. Despite the explosion of new information about the genetics of cancer, only six human genes have thus far been shown to suppress metastasis functionally. Not all have been shown to be functional in breast carcinoma. Several additional genes inhibit various steps of the metastatic cascade, but do not necessarily block metastasis when tested using in vivo assays. The implications of this are discussed. Two recently discovered metastasis suppressor genes block proliferation of tumor cells at a secondary site, offering a new target for therapeutic intervention.

The nm23-H1 gene as a predictor of sensitivity to chemotherapeutic agents in oesophageal squamous cell carcinoma

Recently, nm23-H1, an anti-metastasis gene, has been reported to correlate with sensitivity to chemotherapeutic agents including cisplatin in human breast and ovarian carcinoma cells. The aim of this study was to evaluate a role for nm23-H1 in responsiveness to cisplatin-based chemotherapy in patients with oesophageal squamous cell carcinoma (OSCC). The expression of nm23-H1 protein was examined immunohistochemically in 32 eligible patients with OSCC who underwent adjuvant chemotherapy with cisplatin, etoposide, and 5-fluorouracil after tumour resection. Fifteen (46.9%) of 32 patients were positive for nm23-H1 staining and 17 (53.1%) were negative. Both disease-free survival and overall survival rates of nm23-H1-negative patients were significantly shorter than in nm23-H1-positive patients (P < 0.01 for both). There was no significant difference in clinicopathologic characteristics between nm23-H1-positive and nm23-H1-negative groups. Multivariate analysis also showed that nm23-H1 expression was the most significant factor for overall survival of OSCC patients included in this study (P = 0.0007). To further study the role of nm23-H1, a human OSCC cell line (YES-2) was transfected with a plasmid containing a fragment of the nm23-H1 cDNA in an antisense orientation. Reduced expression of nm23-H1 protein in the antisense-transfected (AS) clones was found by Western blot analysis as compared to wild-type YES-2 and YES-2/Neo (clone transfected with the neomycin resistance gene alone). MTT (3-(4,5-dimethyl-2-thiazol)-2,5-diphenyl-2H tetrazolium bromide) assay showed that reduced expression of the nm23-H1 protein in AS clones was consistent with the degree of increased resistance to cisplatin but not etoposide or 5-fluorouracil. These data support the conclusion that reduced expression of nm23-H1 may be associated with resistance to cisplatin, suggesting the value of nm23-H1 expression as a prognostic marker for OSCC patients who are to undergo cisplatin-based chemotherapy.

Correlation between nm23 protein and several cell adhesion molecules in human gastric carcinoma

The correlation between nm23 protein (nm23) expression and the expression of several cell adhesion molecules was studied immunohistochemically in 110 resected gastric carcinomas. Formalin-fixed and paraffin-embedded samples were serially sectioned and stained with antibodies against nm23, integrin beta1 subfamily members (alpha2beta1, alpha3beta1 and alpha4beta1), LFA-1, ICAM-1, sialyl Lewis(x) (sLex) and CD44H, -V3, and -V6. Primary carcinomas presenting with either lymph node involvement or liver metastasis expressed significantly reduced levels of nm23 compared to tumors without metastasis. The percent of tumors expressing each adhesion molecule was as follows: alpha2beta1, 27.3%; alpha3beta1, 20.0%; alpha4beta1, 14.5%; LFA-1, 14.5%; ICAM-1, 12.7%; sLex, 67.3%; CD44H, 55.5%; CD44V3, 20.0%; and CD44V6, 4.5%. Expression of alpha2beta1 integrin and high levels of sLex were significantly correlated with lymph node metastasis, and expression of alpha3beta1 integrin and high levels of sLex were correlated with liver metastasis. Expression of ICAM-1 was inversely correlated with liver metastasis. Comparing the expression of each cell adhesion molecule with nm23 immunoreactivity, expression of sLex was significantly associated with nm23 expression. Of tumors expressing high levels of sLex, 75% showed reduced nm23 expression, compared to 52% of tumors with weak or no sLex expression (P < 0.05). A similar tendency was also observed in the metastasized secondary tumors. These results suggest that reduced nm23 expression may promote the metastatic properties of cancer cells in concert with increased sLex expression.

Reduced expression of nm23 is associated with metastasis of human gastric carcinomas

Reduced expression of nm23 gene is implicated in high metastatic potential in a variety of malignancies. To elucidate the role of nm23 in human gastric carcinomas, we examined loss of heterozygosity (LOH) of nm23 gene by Southern blotting, nm23 mRNA expression by Northern blotting and nm23 protein expression by Western blotting as well as immunohistochemistry in both primary and metastatic tumors. LOH of nm23 gene was found in 2 (8%) out of the 23 informative gastric carcinomas. Twenty-two (84%) out of the 26 cases expressed nm23 mRNA at higher levels in primary tumor tissue than in corresponding non-neoplastic mucosa. No obvious correlation was observed between clinico-pathological features and LOH of nm23 gene or nm23 mRNA expression. On the other hand, 52% of the gastric carcinomas showed reduction of nm23 immunoreactivity in the metastatic tumor of regional lymph nodes, as compared to the primary tumor. Interestingly, 71% of the gastric carcinomas showed weaker nm23 immunoreactivity in the liver metastasis than in the primary tumor. These results suggest that nm23 overexpression is linked with development of gastric carcinomas and the decrease in expression of nm23 participates in metastasis.