PRDM5 suppresses oesophageal squamous carcinoma cells and modulates 14-3-3zeta/Akt signalling pathway

Dysregulation of PR (PRDI-BF1 and RIZ) domain protein 5 (PRDM5) expression has been shown to be associated with the progression of many malignancies. Nevertheless, the role and underlying mechanism of PRDM5 in oesophageal squamous cell carcinoma (ESCC) remain elusive. qRT-PCR was performed to analyze PRDM5 mRNA expression, and western blot was used to determine protein expression of PRDM5, MMP-2, MMP-9, 14-3-3zeta, pan-Akt and phosphorylated Akt expression. CCK-8 staining was employed to evaluate cell proliferation, while wound scratch assay and Transwell assay were carried out to detect cell migration. A tumour xenograft model of ESCC was also established to validate the effect of PRDM5. PRDM5 expression was downregulated in ESCC tissues and positively correlated with the overall survival of ESCC patients. Silencing PRDM5 expression promoted cell proliferation in ESCC cells, while overexpressing PRDM5 inhibited cell proliferation. Moreover, the migratory abilities of ESCC cells were promoted by PRDM5 knockdown but were attenuated by PRDM5 overexpression. Importantly, 14-3-3zeta expression, along with the phosphorylation of Akt, was suppressed by PRDM5 in ESCC cells. In the established tumour xenograft model, PRDM5 regulated ESCC tumour growth as well as the expression of 14-3-3zeta and phosphorylation of Akt protein. In conclusion, PRDM5 suppresses ESCC cell proliferation and migration and negatively regulates 14-3-3zeta/Akt signalling pathway in vitro and in vivo.

Expression of yhwaz and gene regulation network in hepatocellular carcinoma

The adaptor protein 14-3-3ζ is encoded by the yhwaz gene and implicated in a wide range of biological processes. In tumorigenesis, 14-3-3ζ recognizes specific phosphorylation motifs and interacts with hundreds of target proteins and is, thus, involved in the regulation of tumor proliferation, migration and differentiation. In the present study, bioinformatics tools were used to analyze data from The Cancer Genome Atlas and Gene Expression Omnibus databases and the expression of yhwaz, and gene regulation networks were identified as potentially relevant in hepatocellular carcinoma (HCC). In HCC, yhwaz expression was demonstrated to be upregulated and significantly associated with poor prognosis. Expression levels of microRNAs targeting yhwaz were associated with improved prognosis in patients with liver cancer. Gene networks that are regulated by yhwaz were found to be involved in cell cycle regulation and tumorigenesis, indicating the potential use of the expression levels of yhwaz in liver tissue as predictive biomarkers in patients with liver cancer. In the present study, yhwaz was identified as a gene of interest through data mining gene expression databases and its involvement in regulatory networks in HCC was indicated. Therefore, further in vitro and in vivo studies on the role of yhwaz in the carcinogenesis of HCC would be greatly beneficial.

Autoantibody against 14-3-3 zeta: a serological marker in detection of gastric cancer

PURPOSE

Autoantibody to 14-3-3 zeta was identified in gastric cancer (GC) by serological proteome analysis (SERPA) in our previous study. We comprehensively evaluated its ability to detect GC, determined its association with clinical characteristics, and explored its temporal change in GC patients before and after gastrectomy resection in this study.

METHODS

Anti-14-3-3 zeta antibody was examined by immunoassay in sera from 465 GC patients and 465 normal individuals, and also in 69 serial sera from 26 GC patients before and after resection.

RESULTS

The frequency of anti-14-3-3 zeta were significantly higher in GC group than in control group, with AUC of 0.627. The appearance of anti-14-3-3 zeta showed no difference in different tumor stage, tumor size, tumor differentiation, and lymphatic metastasis, but was higher in GC patients with family tumor history than without family tumor history. When anti-14-3-3 zeta was combined with clinical markers (CEA, CA199 and CA724), the sensitivity increased to 52.7%. In the follow-up analysis, the titer of anti-14-3-3 zeta was higher in post-resection sera than pre-resection sera, and no difference was observed in CEA, CA199 and CA724. Anti-14-3-3 zeta showed an increase from negative status to positive status in six patients after resection, while other three clinical markers presented different change in GC patients after resection.

CONCLUSIONS

Autoantibody against 14-3-3 zeta could be a potential diagnostic biomarker and improve the sensitivity of CEA, CA199 and CA724 in diagnosis of GC. Further largescale studies will be needed to validate its performance in GC patients after resection.

Prognostic significance of YWHAZ expression in localized prostate cancer

BACKGROUND

Prostate cancer (PCa) patients are often over-treated because of the lack of biomarkers needed to distinguish the lethal from the indolent form of PCa. YWHAZ was recently identified as a potential therapeutic target in castration-resistant PCa (CRPC). Therefore, this study focused on determining the prognostic significance of YWHAZ in localized PCa.

METHODS

YWHAZ expression was assessed by immunohistochemistry on formalin-fixed paraffin-embedded tissue from 213 men who underwent radical prostatectomy. Kaplan-Meier analysis and Cox proportional-hazards models were used to assess the prognostic value of YWHAZ intensity.

RESULTS

High YWHAZ expression was strongly associated with high Gleason score at the time of diagnosis (P < 0.001) and PSA relapse (P = 0.001). Importantly, patients with high expression of YWHAZ had a higher risk of CRPC development (P = 0.002) and reduced survival time (P = 0.002).

CONCLUSIONS

Our findings indicate that YWHAZ could serve as a promising prognostic biomarker in localized PCa to predict poor prognosis and to identify a subgroup of tumors, which might benefit from earlier adjuvant or YWHAZ-targeted therapy.

Direct interaction of 14-3-3ζ with ezrin promotes cell migration by regulating the formation of membrane ruffle

14-3-3 proteins have been shown to regulate the actin cytoskeleton remodeling, cell adhesion and migration. In this study, we identified ezrin, a cross-linker between plasma membrane and actin cytoskeleton, as a novel 14-3-3ζ interacting partner. The direct interaction between 14-3-3ζ and ezrin was validated in the cells and by in vitro assays. We showed that the 14-3-3ζ binding region in ezrin was located within the N-terminal and central α-helical domains and that the αG-to-αI helices of 14-3-3ζ are responsible for the binding to ezrin. Functional analyses revealed that the regulation of cell migration and membrane ruffling by 14-3-3ζ is ezrin dependent, for which the integrity of ezrin protein was required. Conversely, the knockdown of 14-3-3ζ abrogates also the stimulatory effect of ezrin on cell migration and membrane ruffling. Moreover, we found that the phosphorylation of Thr567 in ezrin facilitates the 14-3-3ζ-ezrin interaction and the formation of membrane ruffles. Taken together, these results suggest strongly that the functions of these two proteins in cell migration are linked and might be mediated by their direct physical interaction, which is important for the formation of membrane ruffles.

Identification of proteins with increased levels in ameloblastic carcinoma

PURPOSE

The comparative proteomic approach by a combination of 2-dimensional electrophoresis and matrix-assisted laser desorption-ionization-time of flight mass spectrometry (MS) analysis is an attractive strategy for the discovery of cancer biomarkers and therapeutic targets. The identification of protein biomarkers associated with ameloblastic carcinoma (AC), a malignant epithelial odontogenic tumor, will potentially improve the diagnostic and prognostic accuracy for this malignant neoplasm. The aim of the present study was to identify highly expressed proteins in AC that could be considered as potential biomarkers.

MATERIALS AND METHODS

The protein profile of an AC was compared with the protein profiles of 3 cases of benign ameloblastoma. Proteins that showed increased levels in AC were identified using MS, and the augmented amount of some of these proteins in the malignant lesion was confirmed by Western blot or immunohistochemistry.

RESULTS

We detected a total of 782 spots in the protein profile of AC, and 19 of them, showing elevated levels compared with benign ameloblastoma, were identified using MS. These proteins have been implicated in several cellular functions, such as cell structure, metabolism, stress response, and signal transduction.

CONCLUSIONS

The increased expression of the identified proteins and the minor expression of some proteins that might inhibit tumor progression could be involved in the evolution from a benign lesion to carcinoma.

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.

Mitogen activated protein kinase kinase kinase 3 (MAP3K3/MEKK3) overexpression is an early event in esophageal tumorigenesis and is a predictor of poor disease prognosis

BACKGROUND

Mitogen-activated protein kinase kinase kinase3 (MAP3K3/MEKK3) was identified to be differentially expressed in esophageal squamous cell carcinoma (ESCC) using cDNA microarrays by our laboratory. Here in we determined the clinical significance of MEKK3 in ESCC.

METHODS

Immunohistochemical analysis of MEKK3 expression was carried out in archived tissue sections from 93 ESCCs, 47 histologically normal and 61 dysplastic esophageal tissues and correlated with clinicopathological parameters and disease prognosis over up to 7.5 years for ESCC patients.

RESULTS

MEKK3 expression was significantly increased in esophageal dysplasia and ESCC in comparison with normal mucosa (ptrend < 0.001). Kaplan Meier survival analysis showed significantly reduced median disease free survival median DFS = 10 months in patients with MEKK3 positive ESCCs compared to patients with no immunopositivity (median DFS = 19 months, p = 0.04). ESCC patients with MEKK3 positive and lymph node positive tumors had median DFS = 9 months, as compared to median DFS = 21 months in patients who did not show the alterations (p = 0.01). In multivariate Cox regression analysis, combination of MEKK3 overexpression and node positivity [p = 0.015, hazard ratio (HR) = 2.082, 95% CI = 1.154 - 3.756] emerged as important predictor of reduced disease free survival and poor prognosticator for ESCC patients.

CONCLUSIONS

Alterations in MEKK3 expression occur in early stages of development of ESCC and are sustained during disease progression; MEKK3 in combination with lymph node positivity has the potential to serve as adverse prognosticator in ESCC.

Overexpression of YWHAZ relates to tumor cell proliferation and malignant outcome of gastric carcinoma

BACKGROUND

Several studies have demonstrated that YWHAZ (14-3-3ζ), included in the 14-3-3 family of proteins, has been implicated in the initiation and progression of cancers. We tested whether YWHAZ acted as a cancer-promoting gene through its activation/overexpression in gastric cancer (GC).

METHODS

We analysed 7 GC cell lines and 141 primary tumours, which were curatively resected in our hospital between 2001 and 2003.

RESULTS

Overexpression of the YWHAZ protein was frequently detected in GC cell lines (six out of seven lines, 85.7%) and primary tumour samples of GC (72 out of 141 cases, 51%), and significantly correlated with larger tumour size, venous and lymphatic invasion, deeper tumour depth, and higher pathological stage and recurrence rate. Patients with YWHAZ-overexpressing tumours had worse overall survival rates than those with non-expressing tumours in both intensity and proportion expression-dependent manner. YWHAZ positivity was independently associated with a worse outcome in multivariate analysis (P=0.0491, hazard ratio 2.3 (1.003-5.304)). Knockdown of YWHAZ expression using several specific siRNAs inhibited the proliferation, migration, and invasion of YWHAZ-overexpressing GC cells. Higher expression of the YWHAZ protein was significantly associated with the lower expression of miR-375 in primary GC tissues (P=0.0047).

CONCLUSION

These findings suggest that YWHAZ has a pivotal role in tumour cell proliferation through its overexpression, and highlight its usefulness as a prognostic factor and potential therapeutic target in GC.

14-3-3ζ positive expression is associated with a poor prognosis in patients with glioblastoma

BACKGROUND

When identifying clinical markers predicting clinical outcome, disease recurrence and resistance to therapies often determine the diagnosis and therapy of some cancer types.

OBJECTIVE

To investigate whether 14-3-3zeta positive expression is an indicator of prognosis in patients with glioblastoma.

METHODS

Forty-seven patients treated with surgery, radiotherapy, and adjuvant chemotherapy between 2005 and 2007 were divided into 2 groups according to 14-3-3zeta expression in an immunohistochemical study: the 14-3-3zeta negative group (n = 12 patients) and the 14-3-3zeta positive group (n = 35 patients). The clinicopathologic features and survival data for patients in the 14-3-3zeta positive group were compared with data from the patients in the 14-3-3zeta negative group. Kaplan-Meier survival analysis and univariate and multivariate analyses were performed to determine the prognostic factors that influenced patient survival.

RESULTS

14-3-3zeta positive expression was observed in approximately 74.5% of patients with glioblastoma. Patients in the 14-3-3zeta positive group had lower overall survival rates and median survival time than those in the 14-3-3zeta negative group (overall 2-year actuarial survival rates, 8.6% for the 14-3-3zeta positive group vs 16.7% for the 14-3-3zeta negative group; overall 2-year median survival time, 12.9 months for the 14-3-3zeta positive group vs 17.9 months for the 14-3-3zeta negative group, P = .019). 14-3-3zeta positive expression in tumor cells also was correlated with a shorter interval to tumor recurrence (median interval to recurrence, 5.9 months in the 14-3-3zeta positive group vs 8.3 months in the 14-3-3zeta negative group, P = .002). Univariate and multivariate analyses showed that 14-3-3zeta positive expression was an independent prognostic factor.

CONCLUSION

14-3-3zeta positive expression can be used as a potential molecular risk factor in patients with glioblastoma.

14-3-3ζ as a prognostic marker and therapeutic target for cancer

IMPORTANCE OF THE FIELD

The ubiquitously expressed 14-3-3ζ protein is involved in numerous important cellular pathways involved in cancer. Recent research suggests 14-3-3ζ may play a central role regulating multiple pathways responsible for cancer initiation and progression. This review will provide an overview of 14-3-3 proteins and address the role of 14-3-3ζ overexpression in cancer.

AREAS COVERED IN THIS REVIEW

The review covers the basic role of 14-3-3 in regulation of multiple pathways with a focus on 14-3-3ζ as a clinically relevant biomarker for cancer recurrence.

WHAT THE READER WILL GAIN

14-3-3ζ overexpression has been found in multiple cancers; however, the clinical implications were unclear. Recently, 14-3-3ζ has been identified as a biomarker for poor prognosis and chemoresistance in multiple tumor types, indicating a potential clinical application for using 14-3-3ζ in selecting treatment options and predicting cancer patients' outcome.

TAKE HOME MESSAGE

14-3-3ζ is a potential prognostic marker of cancer recurrence and predictive marker for therapeutic resistance. The overexpression of 14-3-3ζ in multiple cancers suggests that it may be a common target to intervene tumor progression; therefore, more efforts are needed for the development of 14-3-3 inhibitors.

Small interfering RNA targeting 14-3-3ζ increases efficacy of chemotherapeutic agents in head and neck cancer cells

Patients diagnosed in advanced stages of head and neck squamous cell carcinoma often show limited response to chemotherapeutic agents. Recently, we reported the overexpression of 14-3-3ζ protein in head and neck premalignant and cancer tissues using liquid chromatography-tandem mass spectrometry with isotopic labeling and revealed its significance as a prognostic marker using immunohistochemical analysis. In this study, we determined the potential of 14-3-3ζ as a therapeutic target for head and neck cancer. Small interfering RNA (siRNA) targeting 14-3-3ζ was used to downregulate its expression in head and neck cancer cells in culture. Cell cycle analysis showed that head and neck cancer cells transfected with siRNA targeting 14-3-3ζ showed G(2)-M arrest. These siRNA transfectants also showed increased cell death on treatment with any one of the following chemotherapeutic agents: cisplatin, 5-fluorouracil, paclitaxel, or doxorubicin in comparison with the no transfection controls. Flow cytometric analysis using propidium iodide staining showed increased sub-G(0) fraction in siRNA-transfected cells treated with any of these chemotherapeutic agents, suggesting cell death; in addition, Annexin V staining and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay revealed increased apoptosis. Taken together, our results strongly showed that downregulation of 14-3-3ζ expression may serve to improve the sensitivity of head and neck cancer cells to chemotherapeutic agents.

14-3-3 sigma and 14-3-3 zeta plays an opposite role in cell growth inhibition mediated by transforming growth factor-beta 1

The expression of 14-3-3 proteins is dysregulated in various types of cancer. This study was undertaken to investigate the effects of 14-3-3 zeta and 14-3-3 sigma on cell growth inhibition mediated by transforming growth factor-beta 1 (TGF-beta1). Mouse mammary epithelial cells (Eph4) that are transformed with oncogenic c-H-Ras (EpRas) and no longer sensitive to TGF-beta1-mediated growth inhibition displayed increased expression of 14-3-3 zeta and decreased expression of 14-3-3 sigma compared with parental Eph4 cells. Using small interfering RNA-mediated knockdown and overexpression of 14-3-3 sigma or 14-3-3 zeta, we showed that 14-3-3 sigma is required for TGF-beta1-mediated growth inhibition whereas 14-3-3 zeta negatively modulates this growth inhibitory response. Notably, overexpression of 14-3-3 zeta increased the level of Smad3 protein that is phosphorylated at linker regions and cannot mediate the TGF-beta1 growth inhibitory response. Consistent with this finding, mutation of the 14-3-3 zeta phosphorylation sites in Smad3 markedly reduced the 14-3-3 zeta-mediated inhibition of TGF-beta1-induced p15 promoter-reporter activity and cell cycle arrest, suggesting that these residues are critical targets of 14-3-3 zeta in the suppression of TGF-beta1-mediated growth. Taken together, our findings indicate that dysregulation of 14-3-3 sigma or 14-3-3 zeta contributes to TGF-beta1 resistance in cancer cells.