Pretreatment 14-3-3 epsilon level is predictive for advanced extranodal NK/T cell lymphoma therapeutic response to asparaginase-based chemotherapy

14-3-3ε: a protein with complex physiology function but promising therapeutic potential in cancer

Over the past decade, the role of the 14-3-3 protein has received increasing interest. Seven subtypes of 14-3-3 proteins exhibit high homology; however, each subtype maintains its specificity. The 14-3-3ε protein is involved in various physiological processes, including signal transduction, cell proliferation, apoptosis, autophagy, cell cycle regulation, repolarization of cardiac action, cardiac development, intracellular electrolyte homeostasis, neurodevelopment, and innate immunity. It also plays a significant role in the development and progression of various diseases, such as cardiovascular diseases, inflammatory diseases, neurodegenerative disorders, and cancer. These immense and various involvements of 14-3-3ε in diverse processes makes it a promising target for drug development. Although extensive research has been conducted on 14-3-3 dimers, studies on 14-3-3 monomers are limited. This review aimed to provide an overview of recent reports on the molecular mechanisms involved in the regulation of binding partners by 14-3-3ε, focusing on issues that could help advance the frontiers of this field. Video Abstract.

The Phosphofurin Acidic Cluster Sorting Protein 2 (PACS-2) E209K Mutation Responsible for PACS-2 Syndrome Increases Susceptibility to Apoptosis

Phosphofurin acidic cluster sorting protein 2 (PACS-2) is a multifunctional cytosolic membrane trafficking protein with distinct roles in maintaining cellular homeostasis. Recent clinical reports have described 28 individuals possessing a de novo PACS-2 E209K mutation that present with epileptic seizures and cerebellar dysgenesis. As the PACS-2 E209K missense mutation has become a marker for neurodevelopmental disorders, we sought to characterize its biochemical properties. Accordingly, we observed that the PACS-2 E209K protein exhibited a slower turnover rate relative to PACS-2 wild type (WT) upon cycloheximide treatment in 293T cells. The longer half-life of PACS-2 E209K suggests a disruption in its proteostasis, with the potential for altered protein-protein interactions. Indeed, a regulatory protein in neurodevelopment known as 14-3-3ε was identified as having an increased association with PACS-2 E209K. Subsequently, when comparing the effect of PACS-2 WT and E209K expression on the staurosporine-induced apoptosis response, we found that PACS-2 E209K increased susceptibility to staurosporine-induced apoptosis in HCT 116 cells. Overall, our findings suggest PACS-2 E209K alters PACS-2 proteostasis and favors complex formation with 14-3-3ε, leading to increased cell death in the presence of environmental stressors.

Towards Next Generation Biomarkers in Natural Killer/T-Cell Lymphoma

Natural killer/T-cell lymphoma (NKTCL) is an Epstein-Barr virus-associated non-Hodgkin lymphoma linked to an aggressive clinical course and poor prognosis. Despite an improvement in survival outcomes with the incorporation of novel agents including immune checkpoint inhibitors in the treatment of NKTCL, a significant proportion of patients still relapse or remain refractory to treatment. Several clinical prognostic models have been developed for NKTCL patients treated in the modern era, though the optimal approach to risk stratification remains to be determined. Novel molecular biomarkers derived from multi-omic profiling have recently been developed, with the potential to improve diagnosis, prognostication and treatment of this disease. Notably, a number of potential biomarkers have emerged from a better understanding of the tumor immune microenvironment and inflammatory responses. This includes a recently described 3'UTR structural variant in the PD-L1 gene, which confers susceptibility to checkpoint immunotherapy. In this review, we summarize the biomarker landscape of NKTCL and highlight emerging biomarkers with the potential for clinical implementation.

Circulating Exosomal MiR-107 Restrains Tumorigenesis in Diffuse Large B-Cell Lymphoma by Targeting 14-3-3η

Exosomes, nanometer-sized membranous vesicles in body fluids, have emerged as promising non-invasive biomarkers for cancer diagnosis. However, the function of exosomes in diffuse large B-cell lymphoma (DLBCL) remains elusive. This study aimed to investigate the role of exosomal miR-107 in lymphomagenesis and explore its clinical significance. In this study, decreased exosomal miR-107, miR-375-3p, and upregulated exosomal miR-485-3p were detected in the plasma of DLBCL patients and showed potential diagnostic value. Downregulated miR-107 expression was associated with advanced Ann Arbor stage, high IPI score, LDH, and β₂-MG level in DLBCL patients. Overexpression of miR-107 by miR-107 Agomir significantly abrogated cell proliferation, induced apoptosis, and inhibited cell invasion in vitro, and repressed tumor growth in vivo. Moreover, the downregulation of miR-107 went in the opposite direction. The target genes of miR-107 were mainly enriched in the PI3K-Akt, Hippo, and AMPK signaling pathways. Notably, upregulated 14-3-3η (YWHAH) was suppressed by miR-107 in DLBCL, suggesting that miR-107 may restrain tumorigenesis by targeting 14-3-3η. In summary, this study unveils the function of miR-107 in lymphomagenesis, highlighting its potential as a diagnostic and prognostic indicator and as a new therapeutic target in the management of DLBCL.

Targeting 14-3-3ε activates apoptotic signaling to prevent cutaneous squamous cell carcinoma

More than a million cases of cutaneous squamous cell carcinoma are diagnosed in the USA each year, and its incidence is increasing. Most of these malignancies arise from premalignant lesions, providing an opportunity for intervention before malignant progression. We previously documented how cytoplasmic mislocalization of CDC25A in premalignant and malignant skin cancers confers resistance to apoptotic cell death via a mechanism that depends on its interaction with 14-3-3ε. From these data, we hypothesized that 14-3-3ε overexpression drives skin tumor development and progression, such that targeting 14-3-3ε may be a useful strategy for skin cancer treatment. Like CDC25A, 14-3-3ε was overexpressed and mislocalized to the cytoplasm of both benign and malignant human skin cancer. Skin-targeted deletion of the 14-3-3ε gene reduced skin tumor development by 75% and blocked malignant progression. 14-3-3ε suppressed apoptosis through activation of Akt, leading to inhibition of BCL2 associated agonist of cell death and upregulation of Survivin. Using virtual tetrapeptide libraries, we developed a novel peptide that specifically blocked 14-3-3ε heterodimerization and thereby prevented its interaction with CDC25A. The peptide reduced prosurvival signaling, killed skin cancer cells and reduced skin tumor growth in xenograft. Normal skin keratinocytes were unaffected by inhibition or deletion of 14-3-3ε. Thus, targeting of 14-3-3ε dimerization is a promising strategy for the treatment of premalignant skin lesions.

Targeting 14-3-3ε-CDC25A interactions to trigger apoptotic cell death in skin cancer

Non-melanoma skin cancer is the most common form of cancer worldwide. We previously documented an anti-apoptotic role for CDC25A in cutaneous squamous cell carcinoma (SCC), an activity dependent on its association with 14-3-3 proteins. We hypothesized that targeting CDC25A-14-3-3ε interactions may be an effective strategy for inducing skin cancer cell apoptosis. Co-immunoprecipitation revealed that CDC25A associated with 14-3-3ε, 14-3-3γ and 14-3-3ζ in SCC cells but not normal keratinocytes. 14-3-3ε and CDC25A activated Akt/BAD/Survivin pro-survival signaling. To target the interaction of 14-3-3ε with CDC25A for cancer therapy, we developed two novel phospho-peptides, pS and pT, corresponding to each of the 14-3-3 binding sites of CDC25A, to specifically interfere with 14-3-3ε binding to CDC25A. Peptides pT (IC₅₀ = 22.1 μM), and pS (IC₅₀ = 29 μM) induced SCC cell death and blocked 14-3-3ε binding to CDC25A. pS or pT treatment of SCC xenografts increased apoptotic cell death and decreased pro-survival P-Akt (S473) and Survivin, demonstrating the effectiveness of the peptides in vivo. These findings lay a framework for the further development of peptides to target 14-3-3ε-CDC25A interactions for skin cancer treatment.

Biomarkers of tumor invasiveness in proteomics (Review)

Over the past two decades, quantitative proteomics has emerged as an important tool for deciphering the complex molecular events involved in cancers. The number of references involving studies on the cancer metastatic process has doubled since 2010, while the last 5 years have seen the development of novel technologies combining deep proteome coverage capabilities with quantitative consistency and accuracy. To highlight key findings within this huge amount of information, the present review identified a list of tumor invasive biomarkers based on both the literature and data collected on a biocollection of experimental cell lines, tumor models of increasing invasiveness and tumor samples from patients with colorectal or breast cancer. Crossing these different data sources led to 76 proteins of interest out of 1,245 mentioned in the literature. Information on these proteins can potentially be translated into clinical prospects, since they represent potential targets for the development and evaluation of innovative therapies, alone or in combination. Herein, a systematical review of the biology of each of these proteins, including their specific subcellular/extracellular or multiple localizations is presented. Finally, as an important advantage of quantitative proteomics is the ability to provide data on all these molecules simultaneously in cell pellets, body fluids or paraffin‑embedded sections of tumors/invaded tissues, the significance of some of their interconnections is discussed.

Acquired Uniparental Disomy Regions Are Associated with Disease Outcome in Patients with Oral Cavity and Oropharynx But Not Larynx Cancers

Acquired uniparental disomy (aUPD) regions pinpoint homozygousity and monoallelic expressed genes. We analyzed The Cancer Genome Atlas single-nucleotide polymorphism arrays and expression data from oral cavity, oropharynx, and larynx cancers to identify frequency of aUPD in each tumor type and association of aUPD regions and differentially expressed genes in the regions with survival. Cox proportional hazard models were used for survival function; and Student’s t test, for differentially expressed genes between groups. The frequency of aUPD was highest in larynx cancers (88.35%) followed by oral cavity (81.11%) and oropharynx cancers (73.85%). In univariate analysis, 11 regions at chromosome 9p were associated with overall survival (OS) in oral cavity cancers. Two regions at chromosome 17p were associated with OS in oropharyngeal cancers, but no aUPD region was associated with survival in patients with larynx cancers. Overexpression of SIGMAR1, C9orf23, and HINT2 was associated with reduced OS in patients with oral cavity cancers, and upregulation of MED27 and YWHAE was associated with shorter OS in patients with oropharynx cancers. In multivariate analysis, four aUPD regions at chromosome 9p and overexpression of HINT2 were associated with shorter OS in oral cavity cancers, and overexpression of MED27 was associated with worse OS in patients with oropharynx cancers. aUPD regions and differentially expressed genes in those regions influence the outcome and may play a role in aggressiveness in oral cavity and oropharynx cancers but not in patients with larynx cancers.

Drosha-independent miR-6778-5p strengthens gastric cancer stem cell stemness via regulation of cytosolic one-carbon folate metabolism

Drosha-dependent canonical microRNAs (miRNAs) play a crucial role in the biological functions and development of cancer. However, the effects of Drosha-independent non-canonical miRNAs remain poorly understood. In our previous work, we found a set of aberrant miRNAs, including some upregulated miRNAs, called Drosha-independent noncanonical miRNAs, in Drosha-knockdown gastric cancer (GC) cells. Surprisingly, Drosha-silenced GC cells still retained strong malignant properties (e.g., proliferation ability and cancer stem cell (CSC) characteristics), indicating that aberrantly upregulated non-canonical miRNAs may play an important role in the maintenance of the malignant properties in GC cells that express low Drosha levels. Here, we report that miR-6778-5p, a noncanonical miRNA, acts as a crucial regulator for maintenance of CSC stemness in Drosha-silenced GC cells. MiR-6778-5p belongs to the 5'-tail mirtron type of non-canonical miRNAs and is transcript splice-derived from intron 5 of SHMT1 (coding cytoplasmic serine hydroxymethyltransferase). It positively regulates expression of its host gene, SHMT1, via targeting YWHAE in Drosha-knockdown GC cells. Similar to its family member SHMT2, SHMT1 plays a crucial role in folate-dependent serine/glycine inter-conversion in one-carbon metabolism. In Drosha wild type GC cells, SHMT2 mediates a mitochondrial-carbon metabolic pathway, which is a major pathway of one-carbon metabolism in normal cells and most cancer cells. However, in Drosha-silenced or Drosha low-expressing GC cells, miR-6778-5p positively regulates SHMT1, instead of SHMT2, thus mediating a compensatory activation of cytoplasmic carbon metabolism that plays an essential role in the maintenance of CSCs in gastric cancer (GCSCs). Drosha wild type GCSCs with SHMT2 are sensitive to 5-fluorouracil; however, Drosha low-expressing GCSCs with SHMT1 are 5-FU-resistant. The loss of miR-6778-5p or SHMT1 notably mitigates GCSC sphere formation and increases sensitivity to 5-fluorouracil in Drosha-knockdown gastric cancer cells. Thus, our study reveals a novel function of Drosha-independent noncanonical miRNAs in maintaining the stemness of GCSCs.

Low Expression of 14-3-3beta Is Associated With Adverse Survival of Diffuse Large B-Cell Lymphoma Patients

Diffuse large B-cell lymphoma (DLBCL), the most common type of non-Hodgkin's lymphoma in the world, is highly heterogeneous. Although current therapies have improved the clinical outcome, 30-40% of the patients are still not cured. Thus, novel treatment options such as targeted therapy is urgently needed. Accumulating evidence suggests that 14-3-3beta protein plays an important role in tumorigenesis and tumor progression. However, the specific roles of 14-3-3beta in DLBCL are still poorly understood. In this study, we retrospectively analyzed 120 archived wax blocks obtained from patients with DLBCL (n = 70) and non-neoplastic lymph nodes (n = 50). Immunohistochemical staining showed that 14-3-3beta gene expression was significantly decreased in DLBCL tissues (P < 0.001) compared to that in non-neoplastic lymph nodes. Low 14-3-3beta expression was significantly correlated with extra-nodal status (P = 0.026), serum LDH level (P = 0.023) and adverse survival of DLBCL patients. In survival analyses, low 14-3-3beta expression was significantly associated with adverse overall survival of the DLBCL patients (P = 0.003). Using the Kaplan-Meier analysis module of the R2 microarray analysis and visualization platform (http://r2.amc.nl), we also confirmed that low expression of 14-3-3beta gene had inferior overall survival in DLBCL patients. Based on our results, we conclude that low expression of 14-3-3beta is associated with adverse survival of diffuse large B-cell lymphoma patients, suggesting a novel prognostic marker and potential therapeutic target.