14-3-3ζ Overexpression and abnormal β-catenin expression are associated with poor differentiation and progression in stage I non-small cell lung cancer

Clinicopathological characteristics and prognosis of resectable lung adenosquamous carcinoma: a population-based study of the SEER database

OBJECTIVE

Adenosquamous carcinoma is a rare subtype of non-small cell lung cancer characterized by aggressive behavior, with combination of adenocarcinoma and squamous cell carcinoma components. The clinicopathological characteristics and prognosis of resectable adenosquamous carcinoma are incompletely understood and this study aimed to depict those in a large population.

METHODS

A total of 805 adenosquamous carcinoma, 7875 squamous cell carcinoma and 23 957 adenocarcinoma patients who underwent lobectomy or sublobectomy were queried from the Surveillance, Epidemiology, and End Results database (2010-17). Clinicopathological characteristics of adenosquamous carcinoma patients were compared with those of squamous cell carcinoma and adenocarcinoma patients. Prognostic factors were identified by univariable and multivariable Cox regression analyses. Propensity score matching was applied to reduce confounding effects.

RESULTS

Adenosquamous carcinoma was associated with higher pleural invasion incidence and poorer differentiation compared with squamous cell carcinoma or adenocarcinoma (P values < 0.001). The independent risk factors of cancer-specific survival of adenosquamous carcinoma patients were increasing age, male sex, invading through visceral pleura, poor differentiation and higher stage. Stage IB adenosquamous carcinoma patients whose tumor invaded through visceral pleura had significantly worse survival than those not (P = 0.003). Adenosquamous carcinoma patients had worse survival compared with squamous cell carcinoma (5-year-survival: 64.55 vs. 69.09%, P = 0.003) and adenocarcinoma (5-year-survival: 64.55 vs. 76.79%, P < 0.001) patients before match. And this difference persisted after match.

CONCLUSIONS

Resectable adenosquamous carcinoma patients had higher pleural invasion incidence, poorer differentiation and worse survival compared with squamous cell carcinoma and adenocarcinoma patients. Visceral pleural invasion status and differentiation grade were vital prognostic factors of adenosquamous carcinoma patients on the basis of stage.

Targeting 14-3-3ζ Overcomes Resistance to Epidermal Growth Factor Receptor-Tyrosine Kinase Inhibitors in Lung Adenocarcinoma via BMP2/Smad/ID1 Signaling

Background: The 14-3-3ζ protein, which acts as a putative oncoprotein, has been found to promote the proliferation, metastasis, and chemoresistance of cancer cells in several cancers including lung adenocarcinoma (LUAD); however, its significance in epidermal growth factor receptor–tyrosine kinase inhibitor (EGFR-TKI) resistance remains unknown.

Methods: The Cancer Genome Atlas (TCGA) database was used to determine 14-3-3ζ expression in pancancer and LUAD. 14-3-3ζ and ID1 expression was then examined in clinical LUAD samples by immunohistochemistry (IHC). Lentiviral transfection with 14-3-3ζ-specific small hairpin RNA (shRNA) was used to establish stable 14-3-3ζ knockdown gefitinib-resistant PC9 (PC9/GR) and H1975 cell lines. The effect of 14-3-3ζ knockdown on reversing EGFR-TKI resistance was determined in vitro by Cell Counting Kit-8 (CCK-8), wound healing, Transwell assays, and flow cytometry. A xenograft tumor model was established to evaluate the role of 14-3-3ζ in EGFR-TKI resistance. Microarray analysis results showed multiple pathways regulated by 14-3-3ζ-shRNA.

Results: In the present study, we demonstrated that based on the TCGA, pancancer and LUAD 14-3-3ζ expression was elevated and predicted unfavorable prognosis. In addition, high 14-3-3ζ expression was associated with advanced T stage, TNM stage, presence of lymph node metastasis and, importantly, poor treatment response to EGFR-TKIs in LUAD patients with EGFR-activating mutations. 14-3-3ζ shRNA sensitized EGFR-TKI-resistant human LUAD cells to gefitinib and reversed epithelial-to-mesenchymal transition (EMT). After 14-3-3ζ depletion, bone morphogenetic protein (BMP) signaling activation was decreased in EGFR-TKI-resistant cells in microarray analysis, which was further validated by Western blot analysis. Furthermore, the expression of 14-3-3ζ positively correlates with ID1 expression in human EGFR-mutant LUAD patient samples. In vivo, there was a reduction in the tumor burden in mice treated with 14-3-3ζ shRNA and gefitinib compared to mice treated with gefitinib alone.

Conclusion: Our work uncovers a hitherto unappreciated role of 14-3-3ζ in EGFR-TKI resistance. This study might provide a potential therapeutic approach for treating LUAD patients harboring EGFR mutations.

Chlorogenic acid-enriched extract of Ilex kudingcha C.J. Tseng tea inhibits neutrophil recruitment in injured zebrafish by promoting reverse migration via the focal adhesion pathway

Neutrophil-regulated inflammation plays crucial roles in tissue damage and repair. Dysregulation of the neutrophil response system can contribute to diseases such as cancer. Clearance of excessive neutrophils at the site of inflammation by reverse migration provides a promising strategy to mitigate the negative effects. Chlorogenic acid treatment of injured zebrafish embryos showed low-developmental toxicity. Using a transgenic zebrafish Tg (mpx: egfp) model, chlorogenic acid-enriched kudingcha extract promoted neutrophil reverse migration via phosphorylation of ERK and AKT. Using i-TRAQ analysis, differentially expressed proteins involved in focal adhesion were identified, such as: Cdc42, SRC, MLC, ITGA, and Calpain. In support of this, ERK and AKT proteins are involved in the focal adhesion pathway. Real time qPCR determined that CGA downregulates genes associated with cancer metastasis, such as: HSPA5, YWHAZ, RP17, and ITGAV. Together, these results suggest that CGA-enriched Kudingcha extract may have potential as an anticancer or anti-inflammatory therapeutic agent. PRACTICAL APPLICATIONS: Ilex kudingcha C.J Tseng, commonly referred to as the large-leaved kudingcha, is a tea variety naturally rich in chlorogenic acid. Chlorogenic acid, the ester of caffeic and quinic acids, has antioxidant, antibacterial, anticancer, and anti-inflammatory, activities. Kudingcha has several known biological functions, including: anticancer, anti-inflammatory, antidiabetic, and hypolipidemic effects. Treatment with kudingcha extract reduces the recruitment of neutrophils, potentially by inhibiting focal adhesion, and activation of cancer metastasis-related genes. Importantly, kudingcha extract could be used as an alternative nutritional supplement for anticancer or anti-inflammation via its ability to suppress neutrophil recruitment.

Combining ctnnb1 genetic variability with epidemiologic factors to predict lung cancer susceptibility

OBJECTIVE

Early detection and diagnosis of lung cancer remain challenging but would improve patient prognosis. The goal of this study is to develop a model to estimate the risk of lung cancer for a given individual.

METHODS

We conducted a case-control study to develop a predictive model to identify individuals at high risk for lung cancer. Clinical data from 500 lung cancer patients and 500 population-based age- and gender-matched controls were used to develop and evaluate the model. Associations between environmental variants together with single nucleotide polymorphisms (SNPs) of beta-catenin (ctnnb1) and lung cancer risk were analyzed using a logistic regression model. The predictive accuracy of the model was determined by calculating the area under the receiver operating characteristic (ROC) curve.

RESULTS

Prior diagnosis of chronic obstructive pulmonary disease (COPD), pulmonary tuberculosis, family history of cancer, and smoking are lung cancer risk factors. The area under the curve (AUC) was 0.740, and the sensitivity, specificity, and Youden index were 0.718, 0.660, and 0.378, respectively.

CONCLUSION

Our risk prediction model for lung cancer is useful for distinguishing high-risk individuals.

14-3-3β exerts glioma-promoting effects and is associated with malignant progression and poor prognosis in patients with glioma

Glioma is a type of tumor that affects the central nervous system. It has been demonstrated that 14-3-3β, a protein that is mainly concentrated in the brain, serves an important role in tumor regulation. However, the mechanism of action of 14-3-3β that underlies the pathogenesis of glioma remains to be elucidated. In the present study, 14-3-3β was silenced by RNA interference in the human glioma cell line U373-MG. Following knockdown of 14-3-3β, the proliferation, colony formation, cell cycle progression, migration and invasion of U373-MG cells were significantly decreased (P<0.01), whereas cell apoptosis was increased (P<0.01). Furthermore, in a tumor xenograft experiment, silencing 14-3-3β significantly inhibited the in vivo tumor growth of U373-MG cells (P<0.01). The results demonstrated that 14-3-3β levels were significantly higher in human glioma tissues compared with normal brain tissues (P<0.01) and high 14-3-3β expression was significantly associated with advanced pathological grade (P<0.03) and low Karnofsky performance scale (P<0.003). Patients with glioma who had high 14-3-3β levels had a significantly shorter survival time compared with those with low expression of 14-3-3β (P=0.031), suggesting that 14-3-3β may be an effective predictor of the prognosis of patients with glioma. The results of the present study indicate that 14-3-3β serves an oncogenic role in glioma, suggesting that 14-3-3β may have potential as a promising therapeutic target for glioma.

14-3-3ζ/TGFβR1 promotes tumor metastasis in lung squamous cell carcinoma

14-3-3ζ is involved in tumor cell growth and apoptosis. However, the mechanism of 14-3-3ζ in lung squamous cell carcinoma (SCC) metastasis has not been illuminated. In our studies, we found that the expression of 14-3-3ζ was highly expressed in lung SCC compared to normal lung tissues. High expression of 14-3-3ζ was associated with pTNM stage (p<0.05) and lymph node metastasis (p<0.05). Furthermore, the expression of 14-3-3ζ protein was associated with high levels of TGFβR1 protein (p=0.005), and pSMAD3 (p=0.033). Lung SCC patients with high 14-3-3ζ expression have significantly shorter OS and DFS compared to patients with low 14-3-3ζ expression. Additionally, 14-3-3ζ knockdown inhibited cell proliferation, migratory and invasive properties of human lung SCC cells. TGFβR1 was involved in 14-3-3ζ-mediated cell proliferation and metastasis of lung SCC cells. Additionally, sh-14-3-3ζ can suppress tumor growth and metastasis in vivo. Thus, these data provide the evidence that 14-3-3ζ promote tumor metastasis and might be a prognostic biomarker and target for therapeutic strategy in lung SCC.

14-3-3ζ promotes hepatocellular carcinoma venous metastasis by modulating hypoxia-inducible factor-1α

Portal vein tumor thrombus (PVTT) is a type of intrahepatic metastasis arising from hepatocellular carcinoma (HCC) and is highly correlated with a poor prognosis. Hypoxia is common in solider tumors, including HCC, where it alters the behavior of HCC cells. We asked whether and how hypoxia contributes to PVTT formation. We demonstrated that increased intratumoral hypoxia is strongly associated with PVTT formation in HCC. We also showed that 14-3-3ζ is induced by hypoxia in HCC cells and correlates with PVTT formation in clinical HCC samples. In addition, 14-3-3ζ up-regulates HIF-1α expression by recruiting HDAC4, which prevents HIF-1α acetylation, thereby stabilizing the protein. Under hypoxic conditions in vitro, 14-3-3ζ knockdown inhibits hypoxia-induced HCC invasion by the HIF-1α/EMT pathway. Blockade of 14-3-3ζ in HCC cells reduces PVTT formation and distant lung metastasis in vivo. Moreover, a combination of 14-3-3ζ and HIF-1α expression is more prognostic for HCC patients than either protein alone. These results suggest that the hypoxia/14-3-3ζ/HIF-1α pathway plays an important role in PVTT formation and HCC metastasis.

14-3-3ζ promotes lung cancer cell invasion by increasing the Snail protein expression through atypical protein kinase C (aPKC)/NF-κB signaling

14-3-3ζ has been identified as a putative oncogene in several cancers, including non-small cell lung cancer (NSCLC). However, the mechanisms underlying its functions remain undefined. In this study, we show that overexpression of 14-3-3ζ was frequently detected in lung adenocarcinoma (LuAC) tissues and was significantly associated with lymph node metastasis and poor outcome. Functional studies demonstrated that 14-3-3ζ promoted migration and invasion in A549 cells, both of which were effectively inhibited when 14-3-3ζ was silenced with short hairpin RNA (shRNA). Furthermore, 14-3-3ζ-mediated invasion of cancer cells was found to upregulate Snail through the activation of atypical protein kinase C (aPKC). Activation of aPKCζ mediates this effect by stimulating NF-κB signaling. Our results identify a specific pathway by which 14-3-3ζ induces tumor invasion and provide insight into potential therapeutic approaches to target 14-3-3ζ-associated lung adenocarcinoma.

A meta-analysis of abnormal β-catenin immunohistochemical expression as a prognostic factor in lung cancer: location is more important

INTRODUCTION

The aim of the study was to evaluate the effect of β-catenin immunohistochemical expression on the prognosis of lung cancer.

MATERIALS AND METHODS

We searched Pubmed and Embase to identify eligible studies. The enrolled references were between January 1985 and January, 2015, with no lower date limit. The citation lists associated with the studies were used to identify additional eligible studies. The data of β-catenin immunohistochemical expression, clinical features and survival in each eligible article were recorded and analyzed as hazard ratio (HR) and odd ratio (OR).

RESULTS

A total of 15 studies were identified and comprised 3404 cases. β-catenin expression was not significantly correlated with poor overall survival (OS) in lung cancer patients (HR 0.79, 95 % CI 0.47-1.34), but showed a significant degree of heterogeneity (I (2) = 95 %, P < 0.0001). Subgroup analysis indicated that accumulation in the nucleus or loss of membrane significantly influences the survival of lung cancer patients independently. But, the result indicated that β-catenin expression was not associated with clinicopathological features such as TNM stage (OR 1.22, 95 % CI 0.69-2.14), T stage (OR 0.86, 95 % CI 0.63-1.17), lymph node metastasis (0.85, 95 % CI 0.41-1.78), distant metastasis (OR 0.82, 95 % CI 0.31-2.18), grade of differentiation (OR 0.92, 95 % CI 0.47-1.80), or vascular invasion (OR 0.99, 95 % CI 0.04-24.10).

CONCLUSION

Abnormal β-catenin immunohistochemical expression might be associated with tumor progression and could be a predictive factor of poor prognosis in patients with lung cancer based on more precise evaluation.

Down-regulation of 14-3-3β exerts anti-cancer effects through inducing ER stress in human glioma U87 cells: Involvement of CHOP-Wnt pathway

We previously identified 14-3-3β as a tumor-specific isoform of 14-3-3 protein in astrocytoma, but its functional role in glioma cells and underlying mechanisms are poorly understood. In the present study, we investigated the effects of 14-3-3β inhibition in human glioma U87 cells using specific targeted small interfering RNA (siRNA). The results showed that 14-3-3β is highly expressed in U87 cells but not in normal astrocyte SVGp12 cells. Knockdown of 14-3-3β by Si-14-3-3β transfection significantly decreased the cell viability but increased the LDH release in a time-dependent fashion in U87 cells, and these effects were accompanied with G0/G1 cell cycle arrest and apoptosis. In addition, 14-3-3β knockdown induced ER stress in U87 cells, as evidenced by ER calcium release, increased expression of XBP1S mRNA and induction of ER related pro-apoptotic factors. Down-regulation of 14-3-3β significantly decreased the nuclear localization of β-catenin and inhibited Topflash activity, which was shown to be reversely correlated with CHOP. Furthermore, Si-CHOP and sFRP were used to inhibit CHOP and Wnt, respectively. The results showed that the anti-cancer effects of 14-3-3β knockdown in U87 cells were mediated by increased expression of CHOP and followed inhibition of Wnt/β-catenin pathway. In summary, the remarkable efficiency of 14-3-3β knockdown to induce apoptotic cell death in U87 cells may find therapeutic application for the treatment of glioma patients.

Targeting LUNX inhibits non-small cell lung cancer growth and metastasis

There remains a great need for effective therapies for lung cancer, the majority of which are non-small cell lung cancers (NSCLC). Here, we report the identification of a novel candidate therapeutic target, LUNX, as a molecule overexpressed in primary NSCLC and lymph node metastases that is associated with reduced postoperative survival. Functional studies demonstrated that LUNX overexpression promoted lung cancer cell migration and proliferation by interactions with the chaperone protein 14-3-3. Conversely, LUNX silencing disrupted primary tumor growth, local invasion, and metastatic colonization. The finding that LUNX was expressed on cell membranes prompted us to generate and characterize LUNX antibodies as a candidate therapeutic. Anti-LUNX could downregulate LUNX and reduce lung cancer cell proliferation and migration in vitro. Administered in vivo to mice bearing lung cancer xenografts, anti-LUNX could slow tumor growth and metastasis and improve mouse survival. Together, our work provides a preclinical proof of concept for LUNX as a novel candidate target for immunotherapy in lung cancer.

Small molecules modulation of 14-3-3 protein-protein interactions

14-3-3 is a family of highly conserved regulatory proteins which is attracting a significant interest due to its potential role as target for pharmacological intervention against cancer and neurodegenerative disorders. Although modulating protein-protein interactions (PPI) is still conceived as a challenging task in drug discovery, in past few years peptide inhibitors and small molecular modulators of 14-3-3 PPI have been described. Here we examine structural and biological features of 14-3-3 and propose an overview on techniques used for discovering small molecular inhibitors and stabilizers of 14-3-3 PPI.

A cancer-related protein 14-3-3ζ is a potential tumor-associated antigen in immunodiagnosis of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the fifth most common cancer and the third leading cause of cancer-related deaths worldwide. Serum alpha-fetoprotein (AFP) is the conventional biomarker currently used in clinical diagnosis of this malignancy. However, AFP is not reliable for early diagnosis, and especially the sensitivity and specificity of AFP in HCC diagnosis are not optimal. Early detection of HCC is an important issue because of the very poor prognosis and usually no more than 6 months survival after diagnosis. Therefore, there is a need for the development of more sensitive and specific methods that can supplement AFP in the early detection of this cancer. In this study, autoantibody responses to 14-3-3ζ in HCC were evaluated by enzyme-linked immunosorbent assay (ELISA), western blot, and indirect immunofluorescence assay. Immunohistochemistry (IHC) with tissue array slides was also performed to analyze protein expression of 14-3-3ζ in HCC and control tissues. The prevalence of autoantibodies against 14-3-3ζ was 16.7% (28/168) in HCC, which was significantly higher than that in liver cirrhosis (LC), chronic hepatitis (CH), and normal human sera (NHS) (P < 0.01). The average titer of autoantibodies against 14-3-3ζ in HCC sera was higher compared to that in LC, CH, and NHS (P < 0.01). In the further study, anti-14-3-3ζ antibodies have been detected in the sera from several HCC patients with serial bleeding samples. A stronger reactive band with 14-3-3ζ in western blot can be seen in sera at 9 months before the clinical diagnosis of HCC. Our preliminary data indicate that anti-14-3-3ζ autoantibodies may be potential biomarkers for early-stage HCC screening and diagnosis.

Proteins differentially expressed in human beta-cells-enriched pancreatic islet cultures and human insulinomas

In view of the great demand for human beta-cells for physiological and medical studies, we generated cell lines derived from human insulinomas which secrete insulin, C-peptide and express neuroendocrine and islet markers. In this study, we set out to characterize their proteomes, comparing them to those of primary beta-cells using DIGE followed by MS. The results were validated by Western blotting. An average of 1800 spots was detected with less than 1% exhibiting differential abundance. Proteins more abundant in human islets, such as Caldesmon, are involved in the regulation of cell contractility, adhesion dependent signaling, and cytoskeletal organization. In contrast, almost all proteins more abundant in insulinoma cells, such as MAGE2, were first described here and could be related to cell survival and resistance to chemotherapy. Our proteomic data provides, for the first time, a molecular snapshot of the orchestrated changes in expression of proteins involved in key processes which could be correlated with the altered phenotype of human beta-cells. Collectively our observations prompt research towards the establishment of bioengineered human beta-cells providing a new and needed source of cultured human beta-cells for beta-cell research, along with the development of new therapeutic strategies for detection, characterization and treatment of insulinomas.

14-3-3β regulates the proliferation of glioma cells through the GSK3β/β-catenin signaling pathway

We previously demonstrated that 14-3-3β is overexpressed in astrocytomas; however, the underlying mechanisms are poorly understood. Based on the reported multiple functions of 14-3-3β, we hypothesized that it interacts with glycogen synthase kinase 3 β (GSK3β), which regulates β-catenin-mediated oncogene expression and contributes to tumorigenesis and astrocytoma progression. To test these hypotheses, we used 14-3-3β overexpression vectors and small interfering RNA (siRNA) transfection in the human normal astrocyte cell line SVGp12 and the glioma cell line U87, respectively. The results showed that overexpression of 14-3-3β promoted the proliferation of SVGp12 cells, while knockdown of 14-3-3β inhibited the proliferation of U87 cells as analyzed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and bromodeoxyuridine (BrdU) assays. In Flag-tagged 14-3-3β-overexpressing cells, GSK3β was co-immunoprecipitated with 14-3-3β using a Flag antibody. Knockdown of β-catenin by siRNA blocked cell proliferation induced by overexpression of 14-3-3β. Furthermore, overexpression of 14-3-3β suppressed the phosphorylation of β-catenin leading to its accumulation and nuclear translocation as revealed by western blot analysis. In addition, β-catenin nuclear translocation induced by overexpression of 14-3-3β activated the transcription of oncogenes including c-myc and cyclin D1. Collectively, these results revealed that 14-3-3β regulates the proliferation of astrocytes and glioma cells through the GSK3β/β-catenin signaling pathway. The delineated mechanism of 14-3-3β may be responsible for the tumorigenesis and progression of human astrocytomas. Thus, new therapeutic strategies or drugs aimed at 14-3-3β may have potential for the treatment of human astrocytomas.

The clinicopathological and prognostic impact of 14-3-3 protein isoforms expression in human cholangiocarcinoma by immunohistochemistry

The 14-3-3 proteins are highly conserved, ubiquitous molecules involved in a variety of biologic phenomena, such as cell cycle control, and apoptosis. However, their expression in cholangiocarcinoma has not been previously characterized. In this paper, immunohistochemistry using specific anti-14-3-3 monoclonal antibodies was performed on formalin-fixed;, paraffin embedded archival tissue from 86 patients of cholangiocarcinoma. We also examined the correlation between expression and survival rate and clinicopathologic factors such as tumor location, tumor size, pathologic differentiation, lymphatic permeation, lymph node metastasis, and tumor stage. Positive 14-3-3 proteins expression was observed for 6 isoforms (β, σ, γ, θ, β, η) of these proteins in 86 patients of cholangiocarcinoma. β and σ isoform immunoreactivity was correlated with lymph node metastasis, tumor stage and patients' survival rate. In addition, δ isoform immunoreactivity showed trends with tumor location, tumor size, pathologic differentiation and tumor stage, while the θ isoform was correlated with pathologic differentiation. These results indicated that upregulated expression of some isoforms of 14-3-3 may be a common mechanism for evading apoptosis in cholangiocarcinoma, so that targeting 14-3-3 may be a novel promising strategy for the treatment of this tumor.

Clinicopathologic significance of β-catenin and matrix metalloproteinase-2 expression in non-small cell lung cancer

The purpose of this study was to analyze β-catenin and matrix metalloproteinase-2 (MMP-2) expression in non-small cell lung cancer (NSCLC) and to investigate the association between their expression and clinicopathologic characteristics of NSCLC patients. Immunohistochemistry was performed to examine β-catenin and MMP-2 protein expression in 39 resected NSCLC samples and 8 adjacent normal lung tissues. Statistical analysis with SPSS13.0 software was performed to investigate the association between β-catenin and MMP-2 expression and clinicopathologic features of the patients. Expression of cytosolic β-catenin in NSCLC tissue was significantly higher than that in normal tissues (P < 0.001). In addition, cytosolic protein expression of β-catenin in lung squamous cell carcinoma was significantly elevated compared to that in lung adenocarcinoma (P = 0.02). However, cell membrane protein expression of β-catenin in squamous cell carcinoma was lower than that in adenocarcinoma (P = 0.041). Cytosolic MMP-2 protein expression in NSCLC samples was significantly higher than that in normal tissues (P = 0.002). MMP-2 expression in N (1-2) NSCLC patients was significantly increased relative to N (0) patients (P = 0.019). However, statistical analysis showed no correlation between β-catenin and MMP-2 expression in NSCLC samples. Collectively, our results show that cytosolic protein expression of β-catenin in NSCLC samples is increased relative to normal lung tissues. Also, expression of β-catenin is significantly elevated in squamous cell carcinoma compared to that in lung adenocarcinoma subtypes. Additionally, MMP-2 expression in N (1-2) NSCLC tissues is higher than that in N (0) lung tissue. There is no correlation between β-catenin and MMP-2 expression in NSCLC, and our study suggests that evaluation of β-catenin and MMP-2 expression may have potential in diagnosis and progression in patients with NSCLC.

Identificationof potential lung cancer biomarkers by liquid chromatography tandem mass spectrometry-based proteomics analysis of secretomes of two lung cancer cell lines

A label-free nano-liquid chromatography tandem mass spectrometry proteomics analysis on the conditioned media (CM) of two lung cancer cell lines of different histological backgrounds to identify secreted or membrane-bound proteins as novel lung cancer biomarkers was performed. Five hundred and seventy seven proteins were identified and 38% of them were classified as extracellular or membrane-bound. For the search of potential biomarkers of lung cancer a series of selection criteria were proposed. We detected known or putative lung cancer markers. In addition, 40 novel proteins were identified, whose role as biomarkers of lung cancer should be explored further.

Implication of 14-3-3ε and 14-3-3θ/τ in proteasome inhibition-induced apoptosis of glioma cells

Proteasome inhibitors represent a novel class of anticancer agents that are used in the treatment of hematologic malignancies and various solid tumors. However, mechanisms underlying their anticancer actions were not fully understood. It has been reported that strong 14-3-3 protein expression is observed and associated with tumor genesis and progression of astrocytoma. In addition, global inhibition of 14-3-3 functions with a general 14-3-3 antagonist difopein induces apoptosis of human astrocytoma cells, validating 14-3-3 as a potential molecular target for anticancer therapeutic management. In the current study, for the first time we demonstrated that proteasome inhibitors downregulated 14-3-3ε and 14-3-3θ/τ in U87 and SF295 glioma cells. Overexpression of 14-3-3ε and 14-3-3θ/τ significantly suppressed apoptosis of human glioma cells induced by proteasome inhibitors. We also demonstrated that MG132 activated ASK1 and siASK1 compromised the MG132-induced apoptosis of glioma cells. Furthermore, overexpression of 14-3-3ε and 14-3-3θ/τ markedly suppressed activation of ASK1. Collectively, the current study supported that proteasome inhibitors, at least in part, caused cytotoxicity of glioma cells via downregulation of 14-3-3ε and 14-3-3θ/τ and subsequent activation of ASK1.

A novel function of YWHAZ/β-catenin axis in promoting epithelial-mesenchymal transition and lung cancer metastasis

YWHAZ, also known as 14-3-3zeta, has been reportedly elevated in many human tumors, including non-small cell lung carcinoma (NSCLC) but little is known about its specific contribution to lung cancer malignancy. Through a combined array-based comparative genomic hybridization and expression microarray analysis, we identified YWHAZ as a potential metastasis enhancer in lung cancer. Ectopic expression of YWHAZ on low invasive cancer cells showed enhanced cell invasion, migration in vitro, and both the tumorigenic and metastatic potentials in vivo. Gene array analysis has indicated these changes associated with an elevation of pathways relevant to epithelial-mesenchymal transition (EMT), with an increase of cell protrusions and branchings. Conversely, knockdown of YWHAZ levels with siRNA or short hairpin RNA (shRNA) in invasive cancer cells led to a reversal of EMT. We observed that high levels of YWHAZ protein are capable of activating β-catenin-mediated transcription by facilitating the accumulation of β-catenin in cytosol and nucleus. Coimmunoprecipitation assays showed a decrease of ubiquitinated β-catenin in presence of the interaction between YWHAZ and β-catenin. This interaction resulted in disassociating β-catenin from the binding of β-TrCP leading to increase β-catenin stability. Using enforced expression of dominant-negative and -positive β-catenin mutants, we confirmed that S552 phosphorylation of β-catenin increases the β-catenin/YWHAZ complex formation, which is important in promoting cell invasiveness and the suppression of ubiquitnated β-catenin. This is the first demonstration showing YWHAZ through its complex with β-catenin in mediating lung cancer malignancy and β-catenin protein stability.

14-3-3 proteins as potential therapeutic targets

The 14-3-3 family of phosphoserine/phosphothreonine-binding proteins dynamically regulates the activity of client proteins in various signaling pathways that control diverse physiological and pathological processes. In response to environmental cues, 14-3-3 proteins orchestrate the highly regulated flow of signals through complex networks of molecular interactions to achieve well-controlled physiological outputs, such as cell proliferation or differentiation. Accumulating evidence now supports the concept that either an abnormal state of 14-3-3 protein expression, or dysregulation of 14-3-3/client protein interactions, contributes to the development of a large number of human diseases. In particular, clinical investigations in the field of oncology have demonstrated a correlation between upregulated 14-3-3 levels and poor survival of cancer patients. These studies highlight the rapid emergence of 14-3-3 proteins as a novel class of molecular target for potential therapeutic intervention. The current status of 14-3-3 modulator discovery is discussed.