The differential expression of aqueous soluble proteins in breast normal and cancerous tissues in relation to stage and grade of patients

Interactions between 14-3-3 Proteins and Actin Cytoskeleton and Its Regulation by microRNAs and Long Non-Coding RNAs in Cancer

14-3-3s are a family of structurally similar proteins that bind to phosphoserine or phosphothreonine residues, forming the central signaling hub that coordinates or integrates various cellular functions, thereby controlling many pathways important in cancer, cell motility, cell death, cytoskeletal remodeling, neuro-degenerative disorders and many more. Their targets are present in all cellular compartments, and when they bind to proteins they alter their subcellular localization, stability, and molecular interactions with other proteins. Changes in environmental conditions that result in altered homeostasis trigger the interaction between 14-3-3 and other proteins to retrieve or rescue homeostasis. In circumstances where these regulatory proteins are dysregulated, it leads to pathological conditions. Therefore, deeper understanding is needed on how 14-3-3 proteins bind, and how these proteins are regulated or modified. This will help to detect disease in early stages or design inhibitors to block certain pathways. Recently, more research has been devoted to identifying the role of MicroRNAs, and long non-coding RNAs, which play an important role in regulating gene expression. Although there are many reviews on the role of 14-3-3 proteins in cancer, they do not provide a holistic view of the changes in the cell, which is the focus of this review. The unique feature of the review is that it not only focuses on how the 14-3-3 subunits associate and dissociate with their binding and regulatory proteins, but also includes the role of micro-RNAs and long non-coding RNAs and how they regulate 14-3-3 isoforms. The highlight of the review is that it focuses on the role of 14-3-3, actin, actin binding proteins and Rho GTPases in cancer, and how this complex is important for cell migration and invasion. Finally, the reader is provided with super-resolution high-clarity images of each subunit of the 14-3-3 protein family, further depicting their distribution in HeLa cells to illustrate their interactions in a cancer cell.

YWHAZ interacts with DAAM1 to promote cell migration in breast cancer

Dishevelled-associated activator of morphogenesis 1 (DAAM1) is a critical driver in facilitating metastasis in breast cancer (BrCa). However, molecular mechanisms for the regulation of DAAM1 activation are only partially elucidated. In this research, the expression levels of YWHAZ and DAAM1 were examined by immunohistochemistry (IHC) staining in BrCa tissues. The functional roles of tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein zeta (YWHAZ)–DAAM1 axis and their regulator microRNA-613 (miR-613) in BrCa cells and associated molecular mechanisms were demonstrated in vitro. As results, the expression levels of DAAM1 and YWHAZ were significantly upregulated in BrCa tissues compared with normal tissues and remarkably associated with poor prognosis. Besides, DAAM1 and YWHAZ were positively correlated with each other in BrCa tissues. YWHAZ interacted and colocalized with DAAM1 in BrCa cells, which was essential for DAAM1-mediated microfilament remodeling and RhoA activation. Moreover, miR-613 directly targeted both YWHAZ and DAAM1, contributing to inhibiting BrCa cells migration via blocking the complex of YWHAZ–DAAM1. To sum up, these data reveal that YWHAZ regulates DAAM1 activation, and the YWHAZ–DAAM1 complex is directly targeted by the shared post-transcriptional regulator miR-613.

Characterization of the expression and prognostic value of 14-3-3 isoforms in breast cancer

The tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation proteins (14-3-3) participate in the tumorigenesis and progression of numerous malignances, but their precise prognostic values in breast cancer (BrCa) remain unknown. Here, we investigated the expression profiles and prognostic roles of 14-3-3 isoforms by employing multiple online databases. The transcriptional levels of most 14-3-3 isoforms in BrCa tissues were significantly higher than those in normal tissues. High mRNA expression of 14-3-3 beta/sigma/theta/zeta was significantly associated with poor overall survival (OS) in BrCa patients, while high mRNA expression of 14-3-3 epsilon was notably related to favorable OS. High mRNA expression of 14-3-3 beta/gamma/sigma/theta/zeta was significantly associated with poor relapse-free survival (RFS) in BrCa patients. A high mutation rate of 14-3-3 was determined to be associated with poor clinical outcomes. In addition, 14-3-3 expression was correlated with the infiltration of specific immune cells types. Analysis of the breast-specific protein-protein interaction (PPI) network suggested that 14-3-3 proteins were involved in several potential oncogenic mechanisms in BrCa. Finally, we performed experimentally validated their oncogenic roles in BrCa. Overall, our findings systematically elucidate the expression and distinct prognostic value of 14-3-3 isoforms in BrCa, which may provide potential therapeutic targets and prognostic biomarkers for BrCa.

The effect of 14-3-3ζ expression on tamoxifen resistance and breast cancer recurrence: a Danish population-based study

PURPOSE

Overexpression of 14-3-3ζ has been linked to breast cancer recurrence in several studies, including studies assessing its effect on tamoxifen resistance. The study was performed to estimate the effect of 14-3-3ζ and differentiate potential prognostic or predictive utility.

METHODS

A case-control study, nested in a population of 11,251 females residing on the Jutland Peninsula of Denmark, was performed. Participants were aged 35-69, diagnosed with stage I, II, or III breast cancer between 1985 and 2001, and registered with the Danish Breast Cancer Cooperative Group. We identified 541 recurrent breast cancer cases with estrogen receptor-positive disease treated with tamoxifen for at least 1 year (ER+/TAM+) and 300 cases with estrogen receptor-negative disease never treated with tamoxifen (ER-/TAM-). We matched cases to controls on ER/TAM status, date of surgery, menopausal status, stage, and county. 14-3-3ζ expression was assessed using immunohistochemistry on tissue microarrays. We computed the odds ratio (OR) associating 14-3-3ζ expression with breast cancer recurrence adjusting for confounding using logistic regression. A quantitative bias analysis was performed to account for bias due to expression assay methods.

RESULTS

Associations for cytoplasmic and nuclear 14-3-3ζ staining above the 50th percentile were near null in both ER+/TAM+ and ER-/TAM- patients. When examining combined 14-3-3ζ staining, the association increased in the ER+/TAM+ group (adjusted OR 1.44, 95% confidence interval (CI) 1.05, 1.99). A nearly twofold increase in odds of recurrence was observed in above the 75th percentile staining of combined 14-3-3ζ, both for ER+/TAM+ patients (adjusted OR 1.93, 95% CI 1.15, 3.24) and ER-/TAM- patients (adjusted OR 1.93, 95% CI 1.03, 3.62), indicating potential prognostic utility.

CONCLUSION

Evidence is lacking to conclude that 14-3-3ζ is a useful marker of tamoxifen resistance; however, 14-3-3ζ expression is a potentially useful prognostic marker of breast cancer recurrence. Independent utility beyond established prognostic markers needs to be determined.

Altered expression of 14-3-3ζ protein in spinal cords of rat fetuses with spina bifida aperta

Background

A large number of studies have confirmed that excessive apoptosis is one of the reasons for deficient neuronal function in neural tube defects (NTDs). A previous study from our laboratory used 2-D gel electrophoresis to demonstrate that 14-3-3ζ expression was low in the spinal cords of rat fetuses with spina bifida aperta at embryonic day (E) 17. As a member of the 14-3-3 protein family, 14-3-3ζ plays a crucial role in the determination of cell fate and anti-apoptotic activity. However, neither the expression of 14-3-3ζ in defective spinal cords, nor the correlation between 14-3-3ζ and excessive apoptosis in NTDs has been fully confirmed.

Methodology/Principal Findings

We used immunoblotting and quantitative real-time PCR (qRT-PCR) to quantify the expression of 14-3-3ζ and double immunofluorescence to visualize 14-3-3ζ and apoptosis. We found that, compared with controls, 14-3-3ζ was down-regulated in spina bifida between E12 and E15. Excessive apoptotic cells and low expression of 14-3-3ζ were observed in the dorsal region of spinal cords with spina bifida during the same time period. To initially explore the molecular mechanisms of apoptosis in NTDs, we investigated the expression of microRNA-7 (miR-7), microRNA-375 (miR-375) and microRNA-451 (miR-451), which are known to down-regulate 14-3-3ζ in several different cell types. We also investigated the expression of p53, a molecule that is downstream of 14-3-3ζ and can be down-regulated by it. We discovered that, in contrast to the reduction of 14-3-3ζ expression, the expression of miR-451, miR-375 and p53 increased in spina bifida rat fetuses.

Conclusions/Significance

These data suggest that the reduced expression of 14-3-3ζ plays a role in the excessive apoptosis that occurs in spina bifida and may be partly regulated by the over-expression of miR-451 and miR-375, and the consequent up-regulation of p53 might further promote apoptosis in spina bifida.