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14-3-3σ functions as an oncogene in colorectal cancer and is associated with therapy resistance. However, the mechanisms underlying these observations are not clear. The results in this report demonstrate that loss of 14-3-3σ in colorectal cancer cells leads to a decrease in tumor formation and increased sensitivity to chemotherapy. The increased sensitivity to chemotherapy is due to a decrease in the expression of UPR pathway genes in the absence of 14-3-3σ. 14-3-3σ promotes expression of the UPR pathway genes by binding to the transcription factor YY1 and preventing the nuclear localization of YY1. YY1, in the absence of 14-3-3σ, shows increased nuclear localization and binds to the promoter of the UPR pathway genes, resulting in decreased gene expression. Similarly, a YY1 mutant that cannot bind to 14-3-3σ also shows increased nuclear localization and is enriched on the promoter of the UPR pathway genes. Finally, inhibition of the UPR pathway with genetic or pharmacological approaches sensitizes colon cancer cells to chemotherapy. Our results identify a novel mechanism by which 14-3-3σ promotes tumor progression and therapy resistance in colorectal cancer by maintaining UPR gene expression., (© 2024 The Author(s). International Journal of Cancer published by John Wiley & Sons Ltd on behalf of UICC.)

Introduction: Intrahepatic cholangiocarcinoma (iCCA) is the second most common primary liver cancer after hepatocellular carcinoma. Through data mining of publicly available iCCA transcriptomic datasets from the Gene Expression Omnibus, we identified SFN as the most significantly up-regulated gene in iCCA compared to normal tissue, focusing on the Gene Ontology term "cell proliferation" (GO:0008283). SFN encodes the 14-3-3σ protein, also known as stratifin, which plays crucial roles in various cellular processes., Materials and Methods: Immunohistochemistry was used to assess stratifin expression in 182 patients with localized iCCAs undergoing surgical resection. Patients were divided into low and high expression groups, and the association between stratifin expression and clinicopathological features was analyzed. Univariate and multivariate survival analyses were performed to assess overall survival (OS), disease-specific survival (DSS), local recurrence-free survival (LRFS), and metastasis-free survival (MeFS)., Results: Elevated stratifin expression in iCCAs was significantly associated with the absence of hepatitis, positive surgical margins, advanced primary tumor stages, and higher histological grades (all p ≤ 0.011). Survival analyses demonstrated a significant negative association between stratifin expression and all prognostic indicators, including OS, DSS, LRFS, and MeFS (all p ≤ 0.0004). Multivariate analysis revealed that stratifin overexpression was significantly correlated with poorer outcomes in terms of DSS, LRFS, and MeFS (all p < 0.001)., Conclusions: These findings suggest that stratifin may play a crucial role in iCCA oncogenesis and tumor progression, serving as a potential novel prognostic biomarker., (Copyright © 2024 Asian Surgical Association and Taiwan Society of Coloproctology. Published by Elsevier B.V. All rights reserved.)

Using supramolecules for protein function regulation is an effective strategy in chemical biology and drug discovery. However, due to the presence of multiple binding sites on protein surfaces, protein function regulation via selective binding of supramolecules is challenging. Recently, the functions of 14-3-3 proteins, which play an important role in regulating intracellular signaling pathways via protein–protein interactions, have been modulated using a supramolecular tweezer, CLR01. However, the binding mechanisms of the tweezer molecule to 14-3-3 proteins are still unclear, which has hindered the development of novel supramolecules targeting the 14-3-3 proteins. Herein, the binding mechanisms of the tweezer to the lysine residues on 14-3-3σ (an isoform in 14-3-3 protein family) were explored by well-tempered metadynamics. The results indicated that the inclusion complex formed between the protein and supramolecule is affected by both kinetic and thermodynamic factors. In particular, simulations confirmed that K214 could form a strong binding complex with the tweezer; the binding free energy was calculated to be −10.5 kcal·mol−1 with an association barrier height of 3.7 kcal·mol−1. In addition, several other lysine residues on 14-3-3σ were identified as being well-recognized by the tweezer, which agrees with experimental results, although only K214/tweezer was co-crystallized. Additionally, the binding mechanisms of the tweezer to all lysine residues were analyzed by exploring the representative conformations during the formation of the inclusion complex. This could be helpful for the development of new inhibitors based on tweezers with more functions against 14-3-3 proteins via modifications of CLR01. We also believe that the proposed computational strategies can be extended to understand the binding mechanism of multi-binding sites proteins with supramolecules and will, thus, be useful toward drug design.

Context Lappaol F (LAF), a natural lignan from Arctium lappa Linné (Asteraceae), inhibits tumour cell growth by inducing cell cycle arrest. However, its underlying anticancer mechanism remains unclear. Objective The effects of LAF on the Hippo-Yes-associated protein (YAP) signalling pathway, which plays an important role in cancer progression, were explored in this study. Materials and methods Cervical (HeLa), colorectal (SW480), breast (MDA-MB-231) and prostate (PC3) cancer cell lines were treated with LAF at different concentrations and different durations. BALB/c nude mice bearing colon xenografts were intravenously injected with vehicle, LAF (10 or 20 mg/kg) or paclitaxel (10 mg/kg) for 15 days. The expression and nuclear localisation of YAP were analysed using transcriptome sequencing, quantitative PCR, western blotting and immunofluorescence. Results LAF suppressed the proliferation of HeLa, MDA-MB-231, SW480 and PC3 cells (IC50 values of 41.5, 26.0, 45.3 and 42.9 μmol/L, respectively, at 72 h), and this was accompanied by significant downregulation in the expression of YAP and its downstream target genes at both the mRNA and protein levels. The expression of 14-3-3σ, a protein that causes YAP cytoplasmic retention and degradation, was remarkably increased, resulting in a decrease in YAP nuclear localisation. Knockdown of 14-3-3σ with small interfering RNA partially blocked LAF-induced YAP inhibition and anti-proliferation effects. In colon xenografts, treatment with LAF led to reduced YAP expression, increased tumour cell apoptosis and tumour growth inhibition. Conclusion LAF was shown to be an inhibitor of YAP. It exerts anticancer activity by inhibiting YAP at the transcriptional and post-translational levels.

Lappaol F (LAF), a natural lignan from Arctium lappa Linné (Asteraceae), inhibits tumour cell growth by inducing cell cycle arrest. However, its underlying anticancer mechanism remains unclear. The effects of LAF on the Hippo-Yes-associated protein (YAP) signalling pathway, which plays an important role in cancer progression, were explored in this study. Cervical (HeLa), colorectal (SW480), breast (MDA-MB-231) and prostate (PC3) cancer cell lines were treated with LAF at different concentrations and different durations. BALB/c nude mice bearing colon xenografts were intravenously injected with vehicle, LAF (10 or 20 mg/kg) or paclitaxel (10 mg/kg) for 15 days. The expression and nuclear localisation of YAP were analysed using transcriptome sequencing, quantitative PCR, western blotting and immunofluorescence. LAF suppressed the proliferation of HeLa, MDA-MB-231, SW480 and PC3 cells (IC50 values of 41.5, 26.0, 45.3 and 42.9 μmol/L, respectively, at 72 h), and this was accompanied by significant downregulation in the expression of YAP and its downstream target genes at both the mRNA and protein levels. The expression of 14-3-3σ, a protein that causes YAP cytoplasmic retention and degradation, was remarkably increased, resulting in a decrease in YAP nuclear localisation. Knockdown of 14-3-3σ with small interfering RNA partially blocked LAF-induced YAP inhibition and anti-proliferation effects. In colon xenografts, treatment with LAF led to reduced YAP expression, increased tumour cell apoptosis and tumour growth inhibition. LAF was shown to be an inhibitor of YAP. It exerts anticancer activity by inhibiting YAP at the transcriptional and post-translational levels. [ABSTRACT FROM AUTHOR]

This study explored the role of 14-3-3σ in carbon ion-irradiated pancreatic adenocarcinoma (PAAD) cells and xenografts and clarified the underlying mechanism. The clinical significance of 14-3-3σ in patients with PAAD was explored using publicly available databases. 14-3-3σ was silenced or overexpressed and combined with carbon ions to measure cell proliferation, cell cycle, and DNA damage repair. Immunoblotting and immunofluorescence (IF) assays were used to determine the underlying mechanisms of 14-3-3σ toward carbon ion radioresistance. We used the BALB/c mice to evaluate the biological behavior of 14-3-3σ in combination with carbon ions. Bioinformatic analysis revealed that PAAD expressed higher 14-3-3σ than normal pancreatic tissues; its overexpression was related to invasive clinicopathological features and a worse prognosis. Knockdown or overexpression of 14-3-3σ demonstrated that 14-3-3σ promoted the survival of PAAD cells after carbon ion irradiation. And 14-3-3σ was upregulated in PAAD cells during DNA damage (carbon ion irradiation, DNA damaging agent) and promotes cell recovery. We found that 14-3-3σ resulted in carbon ion radioresistance by promoting RPA2 and RAD51 accumulation in the nucleus in PAAD cells, thereby increasing homologous recombination repair (HRR) efficiency. Blocking the HR pathway consistently reduced 14-3-3σ overexpression-induced carbon ion radioresistance in PAAD cells. The enhanced radiosensitivity of 14-3-3σ depletion on carbon ion irradiation was also demonstrated in vivo . Altogether, 14-3-3σ functions in tumor progression and can be a potential target for developing biomarkers and treatment strategies for PAAD along with incorporating carbon ion irradiation.

The cytotoxic effect of 5-fluorouracil (5FU) and regorafenib (RF), drugs with different mechanisms of action used to treat colorectal cancer, on an HT29 cell line cultured on plastic or laminin 521 (LM-521) has been studied. It is first shown that LM-521 can increase the sensitivity of tumor cells to 5FU. A possible mechanism of the observed effect of LM-521 on the HT29 cell viability is proposed based on transcriptome and proteome analysis. The interaction of β1-containing integrins on the cell surface with LM-521 can activate the FAK/PI3K/Akt signaling pathways and promote phosphorylation of the YAP transcription coactivator and its binding to the complex with the 14-3-3σ protein. The formation of this complex leads to YAP retention in the cytoplasm and prevents its transport to the nucleus and the activation of antiapoptotic gene transcription. [ABSTRACT FROM AUTHOR]

• 1.14-3-3σ regulates tumor suppressor genes involved in tumor cell cycle progression, inhibits cell proliferation, and accelerates cell apoptosis. • 14-3-3σ can increase DNA repair after damage, and provide new ideas for solving the resistance of tumor cells to radiochemotherapy. • The molecular chaperone property of 14-3-3σ, using its protein-protein interactions, can be used as a new breakthrough in cancer therapy. • 14-3-3σ can accelerate the degradation of oncogenic factor Myc, inhibit tumor glycolysis, mitochondrial biogenesis and other metabolic processes, reverse metabolic reprogramming and play a role in inhibiting tumors. • In short, 14-3-3σ has great potential as a biomolecule for cancer treatment and prognosis. As more studies have focused on the function of 14-3-3 proteins, their role in tumor progression has gradually improved. In the 14-3-3 protein family, 14-3-3σ is the protein that is most associated with tumor occurrence and development. In some malignancies, 14-3-3σ acts as a tumor suppressor via p53 and tumor suppressor genes. In most tumors, 14-3-3σ overexpression increases resistance to chemotherapy and radiotherapy and mediates the G2-M checkpoint after DNA damage. Although 14-3-3σ overexpression has been closely associated with poorer prognosis in pancreatic, gastric and colorectal cancer, its role in gallbladder and nasopharyngeal cancer remains less clear. As such, the function of 14-3-3σ in specific cancer types needs to be further clarified. It has been hypothesized that a role may be related to its molecular chaperone function combined with various protein ligands. In this review, we examine the role of 14-3-3σ in tumor development and drug resistance. We discuss the potential of targeting 14-3-3σ regulators in cancer therapy and treatment. [ABSTRACT FROM AUTHOR]

Objective: 14-3-3σ protein is well known for its tumor suppressive function in breast cancer. However, recent evidence has raised the possibility that the 14-3-3σ protein may also have an oncogenic function in certain cancer types. The aim of this study was to investigate the oncogenic function of 14-3-3σ in adenocarcinoma cell lines of the lung (A549, H358) and colon (HT-29). Material and Methods: siRNA against 14-3-3σ was used to suppress 14-3-3σ expression. Cell proliferation, cell-cycle distribution and expression of related molecules were determined by MTT, flow cytometry, and western blotting, respectively. Results: Down-regulation of 14-3-3σ significantly reduced the proliferation of A549 and H358 by 35.0% and 31.0%, respectively, and significantly induced cell cycle arrest at the G0/G1 and G2/M phases, respectively. Increased p21 expression by 43.0% was only observed in si-14-3-3σ-H358 cells. The si-14-3-3σ-HT-29 cells showed no alteration of cell proliferation and cell-cycle distribution but harbored reduced p53 expression by 56.0% and p27 expression by 67.0%. Conclusion: 14-3-3σ may have an oncogenic function in lung adenocarcinoma but play a different role in colon cancer.

Background/Aims: Type 2 diabetes is associated with oxidative stress and DNA damage which can cause centrosome amplification. Thus, the study investigated centrosome amplification in type 2 diabetes and the underlying mechanisms. Methods: Centrosome numbers in human peripheral blood mononuclear blood cells (PBMC) from healthy subjects and patients with type 2 diabetes were compared to access the association between type 2 diabetes and centrosome amplification. Colon cancer cells were used to investigate the molecular mechanisms underlying the centrosome amplification triggered by high glucose, insulin and palmitic acid. Western blot analysis was used to quantify the level of protein and protein phosphorylation. Immunofluorescent staining was performed to detect centrosomes. ROS was quantified using flow cytometry technique. Transcriptpmic profiling was performed using Illumina HiSeqTM500 platform. Results: We found that centrosome amplification was increased PBMC from the type 2 diabetic patients, which correlated with the levels of fasting blood glucose and HbA1c. High glucose, insulin and palmitic acid, alone or in combinations, induced ROS production and centrosome amplification. Together, they increased AKT activation as well as the expression, binding and centrosome translation of ROCK1 and 14-3-3σ. Results from further analyses showed that AKT-ROS-dependent upregulations of expression, binding and centrosome translocation of ROCK1 and 14-3-3σ was the molecular pathway underlying the centrosome amplification in vitro triggered by high glucose, insulin and palmitic acid. Moreover, the key in vitro molecular signalling events activated by high glucose, insulin and palmitic acid were verified in PBMC from the patients with type 2 diabetes. Conclusion: Our results show that type 2 diabetes promotes cell centrosome amplification, and suggest that the diabetic pathophysiological factors-activated AKT-ROS-dependent signalling of ROCK1 and 14-3-3σ is the underlying molecular mechanism.

We present a unique case of metastatic cholangiocarcinoma with concurrent abdominal cestodiasis in an African green monkey (Chlorocebus pygerythrus) that presented with respiratory insufficiency and abdominal discomfort. There were multiple white–grey masses in the liver and colonic serosa alongside intra-abdominal parasitic cysts. Histopathologically, the liver masses were composed of poorly-differentiated epithelial cells that formed densely cellular solid areas and trabeculae. The neoplastic cells were strongly immunopositive for CK7 but negative for Hep-Par1 antigen, which confirmed a diagnosis of cholangiocarcinoma. Interestingly, there was strong and diffuse neoexpression in the tumour of the cell cycle regulator 14-3-3σ, which is not constitutively expressed in normal liver. There was aberrantly strong expression of E-cadherin, a key cell–cell adhesion protein, in neoplastic cells with evidence of cytoplasmic internalization. This is the first immunohistochemical analysis of 14-3-3σ and E-cadherin in a liver neoplasm in an animal species and the use of these markers requires further investigation in animal liver neoplasms. [ABSTRACT FROM AUTHOR]

Canine gastric carcinoma (CGC) affects both sexes in relatively equal proportions, with a mean age of nine years, and the highest frequency in Staffordshire bull terriers. The most common histological subtype in 149 CGC cases was the undifferentiated carcinoma. CGCs were associated with increased chronic inflammation parameters and a greater chronic inflammatory score when Helicobacter spp. were present. Understanding the molecular pathways of gastric carcinoma is challenging. All markers showed variable expression for each subtype. Expression of the cell cycle regulator 14-3-3σ was positive in undifferentiated, tubular and papillary carcinomas. This demonstrates that 14-3-3σ could serve as an immunohistochemical marker in routine diagnosis and that mucinous, papillary and signet-ring cell (SRC) carcinomas follow a 14-3-3σ independent pathway. p16, another cell cycle regulator, showed increased expression in mucinous and SRC carcinomas. Expression of the adhesion molecules E-cadherin and CD44 appear context-dependent, with switching within tumor emboli potentially playing an important role in tumor cell survival, during invasion and metastasis. Within neoplastic emboli, acinar structures lacked expression of all markers, suggesting an independent molecular pathway that requires further investigation. These findings demonstrate similarities and differences between dogs and humans, albeit further clinicopathological data and molecular analysis are required.

The supramolecular complex formed between protein and designed molecule has become one of the most efficient ways to modify protein functions. As one of the more well-studied model systems, 14-3-3 family proteins play an important role in regulating intracellular signaling pathways via protein-protein interactions. In this work, we selected 14-3-3σ as the target protein. Molecular dynamics simulations and binding free energy calculations were applied to identify the possible binding sites and understand its recognition ability of the supramolecular inhibitor, the tweezer molecule (CLR01). On the basis of our simulation, major interactions between lysine residues and CLR01 come from the van der Waals interactions between the long alkyl chain of lysine and the cavity formed by the norbornadiene and benzene rings of the inhibitor. Apart from K214, which was found to be crystallized with this inhibitor, other lysine sites have also shown their abilities to form inclusion complexes with the inhibitor. Such non-specific recognition features of CLR01 against 14-3-3σ can be used in the modification of protein functions via supramolecular chemistry.

p16 is an important tumor suppressor gene encoded by the INK4A/ARF/INK4B gene locus that is conserved in humans, rodents, and canids. p16 regulates cell cycle in early G1 phase inhibiting transition out of cell cycle from G1/S phase by regulating a multi-protein control complex. p16-associated proteins, cyclin D, CDK4, and CDK6, experience expression level decreases or do not change during cell differentiation and quiescence in contrast to constant p16 expression in post-proliferative cell phases. We hypothesized that p16 has alternate binding partners, other than classical proliferation-associated proteins such as CDKs, in these post-proliferative cell phases. Using co-immunoprecipitation, we have identified 14-3-3σ as a potential alternate binding partner for p16 in quiescent post-proliferative canine mammary cancer cells. Additionally, expression of 14-3-3σ was maintained as fibroblasts exit cell cycle and differentiate to adipocytes simultaneously with continued expression of p16. Based on these results, we suggest that 14-3-3σ protein may be an alternative binding partner for p16 active during cell quiescence and may associate with p16 during cell differentiation. [ABSTRACT FROM AUTHOR]

14-3-3σ is an acidic homodimer protein with more than one hundred different protein partners associated with oncogenic signaling and cell cycle regulation. This review aims to highlight the crucial role of 14-3-3σ in controlling tumor growth and apoptosis and provide a detailed discussion on the structure–activity relationship and binding interactions of the most recent 14-3-3σ protein-protein interaction (PPI) modulators reported to date, which has not been reviewed previously. This includes the new fusicoccanes stabilizers (FC-NAc, DP-005), fragment stabilizers (TCF521-123, TCF521-129, AZ-003, AZ-008), phosphate-based inhibitors (IMP, PLP), peptide inhibitors (2a–d), as well as inhibitors from natural sources (85531185, 95911592). Additionally, this review will also include the discussions of the recent efforts by a different group of researchers for understanding the binding mechanisms of existing 14-3-3σ PPI modulators. The strategies and state-of-the-art techniques applied by various group of researchers in the discovery of a different chemical class of 14-3-3σ modulators for cancer are also briefly discussed in this review, which can be used as a guide in the development of new 14-3-3σ modulators in the near future.

A hypoxic microenvironment contributes to tumor progression, with hypoxia-inducible factor-1α (HIF-1α) being a critical regulator. We have reported that 14-3-3σ is negatively associated with HIF-1α expression; however, its role in hypoxia-induced tumor progression remains poorly characterized. Here we show that 14-3-3σ suppresses cancer hypoxia-induced metastasis and angiogenesis in colorectal cancer (CRC). 14-3-3σ opposes HIF-1α expression by regulating the protein stability of HIF-1α, thereby decreasing HIF-1α transcriptional activity and suppressing tumor progression. Mechanistic studies show that the 14-3-3σ-interacting protein neural precursor cell-expressed developmentally down-regulated 4-like (NEDD4L) is an E3 ligase that targets HIF-1α. 14-3-3σ promotes the binding of S448-phosphorylated NEDD4L to HIF-1α, thereby enhancing HIF-1α poly-ubiquitination and subsequent proteasome-mediated degradation. Consistent with this anti-tumorigenic function for 14-3-3σ, low 14-3-3σ expression levels correlate with poor CRC patient survival, and 14-3-3σ enhances the response of CRC to bevacizumab. These results reveal an important mechanism for 14-3-3σ in tumor suppression through HIF-1α regulation. [Display omitted] • 14-3-3σ inhibits hypoxia-induced CRC metastasis by decreasing HIF-1α expression • 14-3-3σ recruits S448-phosphorylated NEDD4L, which acts as an E3 ligase targeting HIF-1α • 14-3-3σ-induced HIF-1α degradation inhibits angiogenesis and enhances bevacizumab effect • Low 14-3-3σ and high HIF-1α expression lead to poor prognosis of CRC Liu et al. show that 14-3-3σ potentiates the binding of HIF-1α and S448-phosphorylated NEDD4L, an E3 ligase targeting HIF-1α, thereby enhancing HIF-1α poly-ubiquitination and subsequent proteasome-mediated degradation. 14-3-3σ-mediated suppression of HIF-1α inhibits angiogenesis/metastasis and enhances the anti-tumor effect of bevacizumab in colorectal cancer. [ABSTRACT FROM AUTHOR]

Abstract: Chronic kidney disease, the end result of most renal and some systemic diseases, is a common condition where renal function is compromised due to fibrosis. During renal fibrosis, calreticulin, a multifunctional chaperone of the endoplasmic reticulum (ER) is up‐regulated in tubular epithelial cells (TECs) both in vitro and in vivo. Proteomic analysis of cultured TECs overexpressing calreticulin led to the identification of the family of 14‐3‐3 proteins as key proteins overexpressed as well. Furthermore, an increased expression in the majority of 14‐3‐3 family members was observed in 3 different animal models of renal pathologies: the unilateral ureteric obstruction, the nephrotoxic serum administration and the ischaemia‐reperfusion. In all these models, the 14‐3‐3σ isoform (also known as stratifin) was predominantly overexpressed. As in all these models ischaemia is a common denominator, we showed that the ischaemia‐induced transcription factor HIF1α is specifically associated with the promoter region of the 14‐3‐3σ gene. Finally, we evaluated the expression of the family of 14‐3‐3 proteins and specifically 14‐3‐3σ in biopsies from IgA nephropathy and membranous nephropathy patients. These results propose an involvement of 14‐3‐3σ in renal pathology and provide evidence for the first time that hypoxia may be responsible for its altered expression. [ABSTRACT FROM AUTHOR]

FBW7 is an E3 ubiquitin ligase and frequently mutated in various types of cancer. As a component of SCF ubiquitin ligase complex, FBW7 usually targets the substrates via K11 or K48-linked ubiquitylation and subsequent degradation of target proteins. Nevertheless, the role of FBW7 in mediating non-degradable ubiquitin signaling remains unknown in human cancers. In this study, we identified γ-catenin as a new binding protein of FBW7 by TAP-MS (tandem affinity purification-mass spectrum). Knockdown of FBW7 did not affect the stability of γ-catenin, but significantly reduced the K63-linked ubiquitin of γ-catenin, resulting in decreased expression of γ-catenin downstream gene 14-3-3σ. Rescue experiment revealed that γ-catenin promoted the expression of 14-3-3σ in a K63-linked ubiquitin signaling dependent manner. Furthermore, we showed that FBW7 cooperated with γ-catenin to inhibit G2/M cell cycle transition and cell proliferation. Taken together, our study uncovered a novel mechanism that FBW7 associated with γ-catenin and promoted its K63-linked ubiquitylation, providing new insights in understanding the role of FBW7 in inhibiting G2/M cell cycle transition and tumor cell proliferation. [ABSTRACT FROM AUTHOR]

B cells play a critical role in immune responses both in physiological and pathological conditions, and microRNAs have been shown to play important roles in regulating B cell proliferation and function. MiR-146a has been shown to modulate T cell immunity, but its function in regulating B cell response remains partially understood. Our previous studies indicated that germinal center (GC) B cells are significantly expanded in miR-146a-overexpressing (TG) mice. In this study, we further characterized the roles of miR-146a in regulating humoral immune responses to specific antigens. We found that the production of IgE antibody were significantly elevated in TG mice, while the antibody affinity maturation of IgM and IgG were similar between TG mice and the normal controls. We further found higher IgE antibody levels in TG B cell culture supernatant than that in normal controls. A global protein expression comparison of B cells from TG mice and the normal controls through TMT proteomic assay showed that 14-3-3σ, a key factor of immunoglobulin class switch DNA recombination (CSR) in B cells, was highly up-regulated in B cells with overexpression of miR-146a, while Smad4, the target of miR-146a, was decreased. Using an asthma model induced by OVA immunization, we further confirmed the increased level of OVA specific IgE antibodies in TG mice. These results demonstrate that miR-146a enhances class switch and secretion of IgE in B cells by upregulating 14-3-3σ expression, and suggest that miR-146a may be a potential target for asthma therapy. [ABSTRACT FROM AUTHOR]

Lung cancer, in particular, non-small cell lung cancer (NSCLC), is the leading cause of cancer-related mortality. Cis -Diamminedichloroplatinum (cisplatin, CDDP) as first-line chemotherapy for NSCLC, but resistance occurs frequently. We previously reported that Tripartite motif protein 25 (TRIM25) was highly expressed in cisplatin-resistant human lung adenocarcinoma A549 cells (A549/CDDP) in comparison with its parental A549 cells. Herein, we take a further step to demonstrate the association of TRIM25 and cisplatin resistance and also the underlying mechanisms. Knockdown of TRIM25 by RNA interference in A549/CDDP cells decreased half maximal inhibitory concentration (IC 50 ) values and promoted apoptosis in response to cisplatin, whereas overexpression of TRIM25 had opposite effects. More importantly, we found that concomitant knockdown of 14-3-3σ and TRIM25 absolutely reversed the decreased MDM2, increased p53, increased cleaved-Capsese3 and decreased IC 50 value induced by knockdown of TRIM25 individually, suggesting that TRIM25 mediated cisplatin resistance primarily through downregulation of 14-3-3σ. Our results indicate that TRIM25 is associated with cisplatin resistance and 14-3-3σ-MDM2-p53 signaling pathway is involved in this process, suggesting targeting TRIM25 may be a potential strategy for the reversal of cisplatin resistance. [ABSTRACT FROM AUTHOR]

Loss of 14-3-3σ expression through DNA methylation has been associated with carcinogenesis and the prognosis for various cancer types. Detection of methylation of the gene in serum may be useful for diagnostic utility. The present study aimed to investigate the correlation between 14-3-3σ methylation level in 36 paired tumor tissues of non-small cell lung cancer (NSCLC) and matched serum using methylation-specific polymerase chain reaction. The prognostic significance of 14-3-3σ expression in 167 NSCLC was also evaluated using immunohistochemistry. Methylation of the 14-3-3σ gene was identified in all samples. The methylation level in the serum (mean 87.7%, range 64.6-100%) was higher compared with tumor (mean 46.7%, range 25.3-56.3%). However, no significant correlation between methylation levels in tissues and serums was observed (Spearman's correlation, -0.036; P=0.837). In the 167 tumor tissues, the majority of the cases (83.8%) exhibited negative expression. Adenocarcinoma is more likely to exhibit negative expression (91.4%) compared with squamous cell carcinoma (70.2%). No significant difference was identified in the overall survival according to 14-3-3σ expression status and 14-3-3σ expression did not demonstrated independent prognostic significance. In conclusion, NSCLC harbors certain levels of 14-3-3σ methylation in the tumor and the sera of patients. The clinical value of serum 14-3-3σ methylation should be further elucidated. Immunohistochemical expression 14-3-3σ protein has limited value on prognostic significance. [ABSTRACT FROM AUTHOR]

14-3-3σis a cell cycle regulator that has been designed as a ‘double-edged sword’ in the context of human cancers, in which in some it appears to function as a tumour suppressor with decreased expression contributing to tumourigenesis, while in others it may be involved in tissue invasion and metastasis. A variety of studies in both human and canine species have been focused in the immunohistochemical detection of 14-3-3σ, especially in neoplastic diseases. Different commercial available antibodies have been previously used to detect 14-3-3σin canine tissues. This paper shows important differences regarding the pattern of expression between monoclonal and polyclonal antibodies against this protein and proposes the use of the former in future studies of 14-3-3σin canine species. [ABSTRACT FROM PUBLISHER]

ALV-J-SD1005 strain was subcutaneously inoculated into the necks of 1-day-old HY-Line Brown chickens and caused severe growth retardation, viremia and subcutaneous fibrosarcomas in the necks of all infected chickens from 14 days post inoculation (DPI) to 21 DPI, and also significantly increased the expressions of TRIM25, P53, etc., but significantly decreased the expressions of 14-3-3σ, etc. Overexpression of chicken TRIM25 (chTRIM25) significantly promoted cell proliferation and improved the expressions of P53, CDC2, and CDK2 tumor factors; and significantly inhibited the expression of 14-3-3σ in ALV-J-SD1005-infected DF1 cells; but knockdown of chTRIM25 caused the opposite effects. The results of co-immunoprecipitation (Co-IP) and confocal microscopy confirmed that chTRIM25 can recognize and bind 14-3-3σ protein in ALV-J-SD1005-infected cells, and they were co-located in the cytoplasm. It can be concluded that chTRIM25 participates in the fibrous tissue hyperplasia induced by ALV-J-SD1005 infections in chickens by binding 14-3-3σ protein and regulating the expressions of 14-3-3σ, P53, CDC2, and CDK2., Competing Interests: Declaration of Competing Interest The authors declare that they have no competing interests., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Esophageal squamous cell carcinoma (ESCC) is the predominant type of esophageal cancer in Asia. Cisplatin is commonly used in chemoradiation for unresectable ESCC patients. However, the treatment efficacy is diminished in patients with established cisplatin resistance. To understand the mechanism leading to the development of cisplatin resistance in ESCC, we compared the proteomes from a cisplatin-resistant HKESC-2R cell line with its parental-sensitive counterpart HKESC-2 to identify key molecule involved in this process. Mass spectrometry analysis detected 14-3-3σ as the most abundant molecule expressed exclusively in HKESC-2R cells, while western blot result further validated it to be highly expressed in HKESC-2R cells when compared to HKESC-2 cells. Ectopic expression of 14-3-3σ increased cisplatin resistance in HKESC-2 cells, while its suppression sensitized SLMT-1 cells to cisplatin. Among the molecules involved in drug detoxification, drug transportation, and DNA repair, the examined DNA repair molecules HMGB1 and XPA were found to be highly expressed in HKESC-2R cells with high 14-3-3σ expression. Subsequent manipulation of 14-3-3σ by both overexpression and knockdown approaches concurrently altered the expression of HMGB1 and XPA. 14-3-3σ, HMGB1, and XPA were preferentially expressed in cisplatin-resistant SLMT-1 cells when compared to those more sensitive to cisplatin. In ESCC patients with poor response to cisplatin-based chemoradiation, their pre-treatment tumors expressed higher expression of HMGB1 than those with response to such treatment. In summary, our results demonstrate that 14-3-3σ induces cisplatin resistance in ESCC cells and that 14-3-3σ-mediated cisplatin resistance involves DNA repair molecules HMGB1 and XPA. Results from this study provide evidences for further work in researching the potential use of 14-3-3σ and DNA repair molecules HMGB1 and XPA as biomarkers and therapeutic targets for ESCC. [ABSTRACT FROM AUTHOR]

Epigenetic control participates in processes crucial in mammalian development, such as X-chromosome inactivation, gene imprinting, cell type-specific gene expression. We provide evidence that the p53-inducible gene 14-3-3σ is a new example of a gene important to human cancer, where epigenetic mechanisms participate in the control of normal cell type-specific expression, as well as aberrant gene silencing in cancer cells. Like a previously identified cell type-specific gene maspin, 14-3-3σ is a p53-inducible gene; however, it participates in G2/M arrest in response to DNA-damaging agents. 14-3-3σ expression is restricted to certain epithelial cell types, including breast, prostate, whereas expression is absent in nonepithelial tissues such as fibroblasts, lymphocytes. In this report, we show that in normal cells expressing 14-3-3σ, the 14-3-3σ CpG isl, is unmethylated; associated with acetylated histones, unmethylated histone H3 lysine 9;, an accessible chromatin structure. By contrast, normal cells that do not express 14-3-3σ have a methylated 14-3-3σ CpG isl, with hypoacetylated histones, methylated histone H3 lysine 9, an inaccessible chromatin structure. These findings extend the spectrum of cell typespecific genes controlled partly by normal epigenetic mechanisms, suggest that this subset of genes may represent important targets of epigenetic dysregulation in human cancer.

14-3-3 proteins participate in various cellular processes, including apoptosis, proliferation and malignant transformation. 14-3-3σ, a member of the 14-3-3 protein family, is important in several types of cancer; however, little is known about the clinical significance and biological roles of 14-3-3σ in gastric cancer. The present study analyzed the expression pattern of 14-3-3σ in gastric cancer and investigated its correlation with the prognosis of gastric cancer patients. Furthermore, the association of 14-3-3σ with Ki-67, Bcl-2 and Bax was evaluated. 14-3-3s was expressed at higher level in gastric cancer tissue compared with healthy gastric tissue, and 14-3-3σ expression was significantly correlated with tumor size and tumor node metastasis stage (P<0.05). To the best of our knowledge, the present study data are the first to suggest that 14-3-3σ expression has been significantly associated with poor prognosis in gastric cancer. Additionally, 14-3-3σ overexpression was positively correlated with Ki-67 and Bcl-2 expression levels. Thus, 14-3-3s is a potential prognostic marker for gastric cancer patients, and may be involved in regulating the apoptosis and proliferation of gastric cancer cells. [ABSTRACT FROM AUTHOR]

Background 14-3-3σ is implicated in promoting tumor development of various malignancies. However, the clinical relevance of 14-3-3σ in hepatocellular carcinoma (HCC) tumor progression and modulation and pathway elucidation remain unclear. Methods We investigated 14-3-3σ expression in 109 HCC tissues by immunohistochemistry. Overexpression and knockdown experiments were performed by transfection with cDNA or siRNA. Protein expression and cell migration were determined by Western blot and Boyden chamber assay. Results In this study, we found that 14-3-3σ is abundantly expressed in HCC tumors. Stable or transient overexpression of 14-3-3σ induces the expression of heat shock factor-1α (HSF-1α) and heat shock protein 70 (HSP70) in HCC cells. Moreover, expression of 14-3-3σ significantly correlates with HSF-1α/HSP70 in HCC tumors and both 14-3-3σ and HSP70 overexpression are associated with micro-vascular thrombi in HCC patients, suggesting that 14-3-3σ/HSP70 expression is potentially involved in cell migration/invasion. Results of an in vitro migration assay indicate that 14-3-3σ promotes cell migration and that 14-3-3σ-induced cell migration is impaired by siRNA knockdown of HSP70. Finally, 14-3-3σ-induced HSF-1α/HSP70 expression is abolished by the knockdown of β-catenin or activation of GSK-3β. Conclusions Our findings indicate that 14-3-3σ participates in promoting HCC cell migration and tumor development via β-catenin/HSF-1α/HSP70 pathway regulation. Thus, 14-3-3σ alone or combined with HSP70 are potential prognostic biomarkers for HCC. [ABSTRACT FROM AUTHOR]

Early detection of oral lesions (OLs) at high risk of cancer development is of utmost importance for intervention. There is an urgent unmet clinical need for biomarkers that allow identification of high-risk OLs. Recently, we identified and verified a panel of five candidate protein biomarkers namely S100A7, prothymosin alpha, 14-3-3ζ, 14-3-3σ and heterogeneous nuclear ribonucleoprotein K using proteomics to distinguish OLs with dysplasia and oral cancers from normal oral tissues. The objective of our study was to evaluate the potential of these candidate protein biomarkers for identification of oral dysplastic lesions at high risk of cancer development. Using immunohistochemistry, we analyzed expressions of these five candidate protein biomarkers in 110 patients with biopsy-proven oral dysplasia and known clinical outcome and determined their correlations with p16 expression and HPV 16/18 status. Kaplan-Meier survival analysis showed reduced oral cancer-free survival (OCFS) of 68.6 months ( p = 0.007) in patients showing cytoplasmic S100A7 overexpression when compared to patients with weak or no S100A7 immunostaining in cytoplasm (mean OCFS = 122.8 months). Multivariate Cox regression analysis revealed cytoplasmic S100A7 overexpression as the most significant candidate marker associated with cancer development in dysplastic lesions ( p = 0.041, hazard ratio = 2.36). In conclusion, our study suggested the potential of S100A7 overexpression in identifying OLs with dysplasia at high risk of cancer development. [ABSTRACT FROM AUTHOR]

Cdc25 dual-specicity phosphatases are essential regulators at critical stages of cell cycle. Cdc25B is overexpressed in several human tumor types. The activity of Cdc25B is regulated by 14-3-3 dimer. To investigate the roles of Cdc25B and 14-3-3σ in bladder carcinoma, we examined expressions of Cdc25B and 14-3-3σ proteins in bladder carcinoma and cell lines and analyzed their roles in the development and prognosis of urinary bladder carcinoma. Immunohistochmistry was used to detect the expressions of Cdc25B and 14-3-3σ in 105 bladder carcinomas. Moreover, expressions of Cdc25B and 14-3-3σ were analyzed by real-time PCR and Western blot in 40 bladder carcinomas and 20 normal epithelial tissues. Specific siRNA was used to knockdown the expression of Cdc25B or 14-3-3σ. Wild-type plasmid was used to overexpress 14-3-3σ. MTT assay and Flow cytometry were used to examine proliferation and cell cycle of bladder cancer cells. There were higher Cdc25B expression and lower 14-3-3σ expression in carcinomas than in the adjacent normal tissues ( P < 0.05), positive and negative correlations being noted with clinical stage and histopathologic grade. Cdc25B expression was positively correlated with recurrence and poor prognosis. Downregulation of Cdc25B resulted in slower growth, more G2/M cells and 14-3-3σ increasing. However, upregulation and downregulation of 14-3-3σ did not affect cell growth and Cdc25B expression. It showed that Cdc25B upregulation and 14-3-3σ downregulation might promote development of bladder cancer and suggested a poor prognosis. Moreover, Cdc25B could play an important role on the bladder cancer cell proliferation and cell cycle progression and regulate expression of 14-3-3σ. [ABSTRACT FROM AUTHOR]

Background Deoxyribonucleic acid damage activates cell cycle checkpoints in order to maintain genomic stability. We assessed the role of different checkpoint genes in response to ultraviolet B irradiation. Methods Cell lines expressing a dominant negative mutant of ataxia telangiectasia and Rad3 related ( Atr) protein or overexpressing Cdc25A, cells deficient for 14-3-3σ, Nijmegen breakage syndrome ( Nbs), or Ataxia telangiectasia mutated ( Atm) were treated with ultraviolet B ( UVB) and harvested after 12 h, 24 h, or 48 h for analysis by flow cytometry. Results Functional loss of Atm, Atr, or Nbs did not result in a significant alteration of the cell cycle profile. Overexpression of Cdc25A led to a delayed arrest at the G1/S transition in response to low doses of UVB. Loss of 14-3-3σ, a negative cell cycle regulator and downstream target of p53, caused a transient arrest at the G2/M boundary. Conclusions Loss of 14-3-3σ sensitizes cells to UVB. After a transient cell cycle arrest, 14-3-3σ-deficient cells die by undergoing mitotic catastrophe. Cdc25A overexpression causes a delayed arrest in response to low doses of UVB. After higher doses, Cdc25A is no longer able to overrun the checkpoint. Atm, Atr, or Nbs are not essential for the checkpoint response to UVB, suggesting the existence of redundant signaling pathways. [ABSTRACT FROM AUTHOR]

Uterine papillary serous carcinoma (UPSC) morphologically resembles ovarian serous carcinoma and is categorized as a type II endometrial cancer. UPSC comprises about 10% of all types of endometrial cancer and has an aggressive clinical course and a poor prognosis. The 14-3-3σ gene was originally discovered as a p53-inducible gene; its expression is induced by DNA damage in a p53-dependent manner, which leads to G2 arrest and repair of damaged DNA. Moreover, it has been reported that expression of 14-3-3σ is frequently lost in various types of human cancer, including ovarian cancer. We therefore examined the association between 14-3-3σ expression determined by immunohistochemistry and clinical outcomes of 51 patients with UPSC. UPSC was considered positive for 14-3-3σ when > 30% of tumor cells were stained with a specific antibody. Of these patients, 29 (58.7%) showed positive immunoreactivity for 14-3-3σ and 22 (41.3%) had decreased 14-3-3σ staining. Decreased immunoreactivity for 14-3-3σ was associated with stage (P = 0.001) and lymphovascular space involvement (P = 0.005). Moreover, decreased 14-3-3σ expression was an independent risk factor for reduced overall survival (P = 0.0416) in multivariate analysis. Direct bisulfite sequencing was performed to evaluate the methylation status of the 27 CpG islands in the promoter region and first exon of the 14-3-3σ gene. These CpG islands were hypermethylated in 30% of 14-3-3σ -positive UPSC and 80% of 14-3-3σ -negative UPSC, although the difference was not statistically significant. These findings suggest that decreased expression of immunoreactive 14-3-3σ may be a predictor of poor prognosis in patients with UPSC. [ABSTRACT FROM AUTHOR]

The efficacies of chemotherapeutic agents are often limited by side effects and acquired drug resistance. We have investigated whether the differential expression pattern of 14-3-3σ affects cisplatin response in non-small cell lung cancer cell lines. Two pairs of parental/cisplatin resistant cell lines (A549/CRA549 and Calu1/CR-Calu1) and clinical lung cancer biopsy samples were analysed for 14-3-3σ expression. Cell viability was assessed by WST assay; and 14-3-3σ expression was suppressed by siRNA transfection. 14-3-3σ mRNA expression increased in CR-A549 and CR-Calu1 compared with their cisplatin-sensitive parental A549 and Calu1 cell lines. But when 14-3-3σ expression was suppressed, elevated cisplatin response was seen in A549 and CR-Calu1 cell lines. Increased 14-3-3σ expression might also account for reduced cisplatin response in vivo, since, 14-3-3σ expression in clinical biopsy samples obtained from lung cancer patients undergoing cisplatin-based chemotherapy significantly higher in the non-responder compared with the responder group. We therefore propose that increased 14-3-3σ expression is correlated with cisplatin response in non-small cell lung cancer cells; monitoring its expression might become useful in the future in predicting poor outcome to cisplatin treatment and/or the verification of acquired cisplatin resistance in lung cancer patients. [ABSTRACT FROM AUTHOR]

Using supramolecules for protein function regulation is an effective strategy in chemical biology and drug discovery. However, due to the presence of multiple binding sites on protein surfaces, protein function regulation via selective binding of supramolecules is challenging. Recently, the functions of 14-3-3 proteins, which play an important role in regulating intracellular signaling pathways via protein-protein interactions, have been modulated using a supramolecular tweezer, CLR01. However, the binding mechanisms of the tweezer molecule to 14-3-3 proteins are still unclear, which has hindered the development of novel supramolecules targeting the 14-3-3 proteins. Herein, the binding mechanisms of the tweezer to the lysine residues on 14-3-3σ (an isoform in 14-3-3 protein family) were explored by well-tempered metadynamics. The results indicated that the inclusion complex formed between the protein and supramolecule is affected by both kinetic and thermodynamic factors. In particular, simulations confirmed that K214 could form a strong binding complex with the tweezer; the binding free energy was calculated to be -10.5 kcal·mol -1 with an association barrier height of 3.7 kcal·mol -1 . In addition, several other lysine residues on 14-3-3σ were identified as being well-recognized by the tweezer, which agrees with experimental results, although only K214/tweezer was co-crystallized. Additionally, the binding mechanisms of the tweezer to all lysine residues were analyzed by exploring the representative conformations during the formation of the inclusion complex. This could be helpful for the development of new inhibitors based on tweezers with more functions against 14-3-3 proteins via modifications of CLR01. We also believe that the proposed computational strategies can be extended to understand the binding mechanism of multi-binding sites proteins with supramolecules and will, thus, be useful toward drug design., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Zhou, Shi, Wang and Xu.)

Abstract: Ascorbic acid (vitamin C) is an essential component of most living cells. Apart from antioxidant activity, it has been reported to inhibit cancer cell growth in vitro in human cancer cells. However, the cellular mechanism underlying anticancer activity has not been fully elucidated. In this study, vitamin C showed a cytotoxic effect on human gastric cancer cell line AGS (LD50 300μg/ml). Further, flow cytometry analysis showed that vitamin C increased the sub-G1 (apoptosis) population and apoptosis confirmed by fluorescein isothiocyanate–Annexin V double staining in AGS cells. Moreover, specific immuno-blotting revealed the expression of the phosphorylated form of Bad (S136), 14–3-3σ, pro-caspases-3, -6, -8, and-9 protein levels were significantly decreased and Bax/Bcl-xL ratio was increased in a dose-dependent manner. Also, wound healing assay results showed that vitamin C inhibited AGS cell proliferation. These findings suggest that vitamin C induces apoptosis and might be a potential therapeutic agent for gastric cancer. [Copyright &y& Elsevier]

14-3-3σ is a tumor suppressor gene induced by p53 in response to DNA damage and reportedly associated with resistance to chemotherapy. The aim of this study was to investigate whether 14-3-3σ expression is also associated with resistance to neoadjuvant chemotherapy consisting of paclitaxel followed by 5-FU/epirubicin/cyclophosphamide (P-FEC) in human breast cancer patients. A total of 123 primary breast cancer patients treated with neoadjuvant chemotherapy (P-FEC) were included in this study. Immunohistochemistry of 14-3-3σ and p53 as well as direct sequencing of TP53 were performed using the tumor biopsy samples obtained prior to neoadjuvant chemotherapy. Thirty-eight of the tumors (31%) were positive for 14-3-3σ. There was no significant association between 14-3-3σ expression and TP53 mutation or p53 expression. However, 14-3-3σ expression showed a significantly ( P = 0.009) negative association with pathological complete response (pCR) to P-FEC, and multivariate analysis demonstrated that only 14-3-3σ ( P = 0.015) and estrogen receptor ( P = 0.021) were significantly and independently associated with pCR. The combination of 14-3-3σ expression and TP53 mutation status had an additive negative effect on pCR, i.e., pCR rates were 45.5% for 14-3-3σ negative/TP53 mutant tumors, 24.6% for 14-3-3σ negative/ TP53 wild tumors, 23.1% for 14-3-3σ positive/TP53 mutant tumors, and 0% for 14-3-3σ positive/ TP53 wild tumors. These results demonstrate that 14-3-3σ expression is significantly associated with resistance to P-FEC and this association is independent of other biological markers. The combination of 14-3-3σ expression and TP53 mutation status has an additively negative effect on the response to P-FEC. [ABSTRACT FROM AUTHOR]

Gamboge is a traditional Chinese medicine and our previous study showed that gambogic acid and gambogenic acid suppress the proliferation of HCC cells. In the present study, another active component, 1,3,6,7-tetrahydroxyxanthone (TTA), was identified to effectively suppress HCC cell growth. In addition, our Hoechst-PI staining and flow cytometry analyses indicated that TTA induced apoptosis in HCC cells. In order to identify the targets of TTA in HCC cells, a two-dimensional gel electrophoresis was performed, and proteins in different expressions were identified by MALDA-TOF MS and MS/MS analyses. In summary, eighteen proteins with different expressions were identified in which twelve were up-regulated and six were down-regulated. Among them, the four most distinctively expressed proteins were further studied and validated by western blotting. The β-tubulin and translationally controlled tumor protein were decreased while the 14-3-3σ and P16 protein expressions were up-regulated. In addition, TTA suppressed tumorigenesis partially through P16-pRb signaling. 14-3-3σ silence reversed the suppressive effect of cell growth and apoptosis induced by introducing TTA. In conclusion, TTA effectively suppressed cell growth through, at least partially, up-regulation of P16 and 14-3-3σ. [ABSTRACT FROM AUTHOR]

Abstract: We previously demonstrated that 14-3-3σ was downregulated in 5-fluorouracil (5-Fu)-resistant MCF-7 breast cancer cells (MCF-7/5-Fu). Here, we found that stably enhanced 14-3-3σ expression strengthened the effects of 5-Fu, Mitoxantrone and cDDP. 14-3-3σ stabilised the p53 protein and bound Akt to inhibit its activity and its downstream targets: survivin, Bcl-2 and NF-κB-p50. In addition, decreased p53 expression, but not promoter hypermethylation, was responsible for the downregulation of 14-3-3σ in MCF-7/5-Fu cells. Meanwhile, initial treatments with high concentrations of 5-Fu clearly induced 14-3-3σ and p53 expression in a time-dependent manner. 14-3-3σ-mediated molecular events that synergise with p53 may play important roles in the chemotherapy of breast cancer. [Copyright &y& Elsevier]

Purpose: Our aim was to define dose-dependent and genotype-dependent components of radiosensitivity by resolving patterns of radiation-induced clonal inactivation into specific responses. Methods: In a set of 10 tumour cells with varying expression of radiosensitivity and genotype, we identified doses at which all tumour cells change in their rate of clonogenic inactivation. We tested intervening dose-segments as to whether inactivation was constant, expressing inactivation as a log-linear function of dose. We compared these segments to components proposed in the Hit-target (HT) model and the Linear-quadratic (LQ) model. Temporal changes in redistribution in cell-cycle prevalence and apoptosis were examined as essential components of cellular radiosensitivity. Results: We identified four distinct responses induced sequentially in all cells independent of genotype. Rates of inactivation within each response varied with expression of genotype and identified: (i) A hypersensitive component H (0.0--0.10 Gy); (ii) a resistant component R (0.1--0.2 Gy); (iii) an induced repair response alpha** (0.2 Gy and higher); and (iv) a more sensitive component omega** (3.0 Gy and higher). The H, alpha** and omega** components were fitted well by log-linear patterns, the R response did not. Conclusions: Four distinct, sequentially-induced responses comprise cellular radiosensitivity. H and R responses are associated with low dose hyper-radiosensitivity and early apoptosis, while the alpha** and omega** responses share characteristics of the HT and LQ models and are associated with post-repair apoptosis. Radiation induces these four responses at the same doses in all cells, but the rate of inactivation over each response depends on genotype. [ABSTRACT FROM AUTHOR]

This study aimed to explore the mechanism of multi-drug resistance (MDR) in 5-fluorouracil (5-FU)-induced breast cancer cell MCF-7. MCF-7 cells were exposed in stepwise escalating concentration of 5-FU to develop the resistant cell line, MCF-7/5-FU. Biological and molecular characteristics of the cells were studied through MTT, flow cytometry, real-time PCR, western-blot, and the global protein profiles between MCF-7/5-FU and parental MCF-7 were compared using proteomic approach. Then some of the differentially expressed proteins were validated by western-blot. In addition, the role of 14-3-3σ was validated using gene transfection. Drug resistance of MCF-7/5-FU cells to 5-FU, MX, cDDP, ADM, TAXOL all increased significantly compared with MCF-7 cells and that maybe related to BCRP, but not MDR1 and MRP1. Differentially expressed proteins between MCF-7/5-FU and MCF-7 cells were identified; 12 proteins were up-regulated and 18 proteins were down-regulated in MCF-7/5-FU cells. Expressive levels of some proteins in western-blot validation were consistent with the results in proteomic analysis. Enforced 14-3-3σ expression can increase the sensitivity of MCF-7/5-FU cells to 5-FU and cDDP. MDR of MCF-7/5-FU likely associated with differentially expressed proteins and 14-3-3σ may play a positive role in chemotherapy. These findings may provide theoretical support for the prediction of chemotherapeutic response and reverse of MDR. [ABSTRACT FROM AUTHOR]

Abstract: 14-3-3σ (also called stratifin) is specifically expressed in the stratified squamous epithelium and its function was recently shown to be linked to epidermal stratification and differentiation in the skin. In this study, we investigated its role in corneal epithelium cell proliferation and differentiation. We showed that the 14-3-3σ mutation in repeated epilation (Er) mutant mice results in a dominant negative truncated protein. Primary corneal epithelial cells expressing the dominant negative protein failed to undergo high calcium-induced cell cycle arrest and differentiation. We further demonstrated that blocking endogenous 14-3-3σ activity in corneal epithelial cells by overexpressing dominative negative 14-3-3σ led to reduced Notch activity and Notch1/2 transcription. Significantly, expression of the active Notch intracellular domain overcame the block in epithelial cell differentiation in 14-3-3σ mutant-expressing corneal epithelial cells. We conclude that 14-3-3σ is critical for regulating corneal epithelial proliferation and differentiation by regulating Notch signaling activity. [Copyright &y& Elsevier]

Abstract: 14-3-3σ is a potential tumor suppressor, and loss of 14-3-3σ expression plays an important role in carcinogenesis and metastasis. To explore the possible mechanism of 14-3-3σ in nasopharyngeal carcinoma (NPC) invasion and metastasis, targeted proteomic analysis was performed on 14-3-3σ-associated proteins from NPC cells. As the results, 112 proteins associated with 14-3-3σ were identified, and four 14-3-3σ-interacted proteins: keratin 8, epidermal growth factor receptor (EGFR), small GTP-binding protein RAB7, and p53 were confirmed by coimmunoprecipitation and Western blot analysis. The 14-3-3σ-associated proteins could be grouped into eight clusters based on their molecule functions. Protein–protein interaction (PPI) analysis indicated that 14-3-3σ/EGFR/keratin 8 interactions may be involved in the invasion and metastasis of NPC. 14-3-3σ/EGFR/keratin 8 could form complexes in NPC cells. 14-3-3σ downregulation in NPC may lead to the overexpression of EGFR and keratin 8, which increases the invasion ability of NPC cells possibly by activating the downstream signal molecules and reorganizing cytoskeleton. The data suggest that the biological functions of 14-3-3σ in NPC are diversified, and 14-3-3σ could inhibit the in vitro invasive ability of NPC cells possibly through 14-3-3σ/EGFR/keratin 8 interaction. [Copyright &y& Elsevier]

The protein 14-3-3σ is involved in the regulation of cellular processes such as apoptosis, cell cycle progression and proliferation. Disruption of protein expression has been implicated in a number of malignancies. Here we examine the expression pattern of 14-3-3σ in breast cancer and specifically consider whether expression in ductal carcinoma in situ (DCIS) lesions is predictive of disease outcome. We examined 14-3-3σ protein expression and localization using immunohistochemical staining on a high-density tissue microarray consisting of 157 invasive breast cancer patients. Statistical analyses were used to assess the correlation of 14-3-3σ expression with clinico-pathological parameters and patient outcome. We observed a statistically significant increase in 14-3-3σ protein expression in ductal hyperplasia, DCIS, and invasive ductal carcinoma (IDC) as compared normal glandular epithelium. In IDC, lower expression of 14-3-3σ tended to predicted poorer survival time while in DCIS lesions, there was a stronger correlation between relatively higher levels of 14-3-3σ predicting shorter survival time. Further, of patients who had concurrent DCIS and IDC lesions, those that exhibited a decrease of 14-3-3σ expression from DCIS to IDC had significantly shorter survival time. Our findings indicate that 14-3-3σ expression may be a useful prognostic indicator for survival in patients with breast cancer with an elevated 14-3-3σ in earlier disease predicting a less favorable disease outcome. To our knowledge this is the first published study associating 14-3-3σ protein expression with breast cancer survival. [ABSTRACT FROM AUTHOR]