Increased expression of amyloid precursor protein in oral squamous cell carcinoma

Anthracene detoxification by Laccases from indigenous fungal strains Trichoderma lixii FLU1 and Talaromyces pinophilus FLU12

The persistence and ubiquity of polycyclic aromatic hydrocarbons (PAHs) in the environment necessitate effective remediation strategies. Hence, this study investigated the potential of purified Laccases, TlFLU1L and TpFLU12L, from two indigenous fungi Trichoderma lixii FLU1 (TlFLU1) and Talaromyces pinophilus FLU12 (TpFLU12), respectively for the oxidation and detoxification of anthracene. Anthracene was degraded with vmax values of 3.51 ± 0.06 mg/L/h and 3.44 ± 0.06 mg/L/h, and Km values of 173.2 ± 0.06 mg/L and 73.3 ± 0.07 mg/L by TlFLU1L and TpFLU12L, respectively. The addition of a mediator compound 2,2-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) to the reaction system significantly increased the degradation of anthracene, with up to a 2.9-fold increase in vmax value and up to threefold decrease in Km values of TlFLU1L and TpFLU12L. The GC-MS analysis of the metabolites suggests that anthracene degradation follows one new pathway unique to the ABTS system-hydroxylation and carboxylation of C-1 and C-2 position of anthracene to form 3-hydroxy-2-naphthoic acid, before undergoing dioxygenation and side chain removal to form chromone which was later converted into benzoic acid and CO2. This pathway contrasts with the common dioxygenation route observed in the free Laccase system, which is observed in the second degradation pathways. Furthermore, toxicity tests using V. parahaemolyticus and HT-22 cells, respectively, demonstrated the non-toxic nature of Laccase-ABTS-mediated metabolites. Intriguingly, analysis of the expression level of Alzheimer's related genes in HT-22 cells exposed to degradation products revealed no induction of neurotoxicity unlike untreated cells. These findings propose a paradigm shift for bioremediation by highlighting the Laccase-ABTS system as a promising green technology due to its efficiency with the discovery of a potentially less harmful degradation pathway, and the production of non-toxic metabolites.

Novel genetic variants in the NLRP3 inflammasome-related PANX1 and APP genes predict survival of patients with hepatitis B virus-related hepatocellular carcinoma

BACKGROUND

The nod-like receptor protein 3 (NLRP3) is one of the most characterized inflammasomes involved in the pathogenesis of several cancers, including hepatocellular carcinoma (HCC). However, the effects of genetic variants in the NLRP3 inflammasome-related genes on survival of hepatitis B virus (HBV)-related HCC patients are unclear.

METHODS

We performed multivariable Cox proportional hazards regression analysis to evaluate associations between 299 single-nucleotide polymorphisms (SNPs) in 16 NLRP3 inflammasome-related genes and overall survival (OS) of 866 patients with HBV-related HCC. We further performed expression quantitative trait loci (eQTL) analysis using the data from the GTEx project and 1000 Genomes projects, and performed differential expression analysis using the TCGA dataset to explore possible molecular mechanisms underlying the observed associations.

RESULTS

We found that two functional SNPs (PANX1 rs3020013 A > G and APP rs9976425 C > T) were significantly associated with HBV-related HCC OS with the adjusted hazard ratio (HR) of 0.83 [95% confidence interval (CI) = 0.73-0.95, P = 0.008], and 1.26 (95% CI = 1.02-1.55, P = 0.033), respectively. Moreover, the eQTL analysis revealed that the rs3020013 G allele was correlated with decreased mRNA expression levels of PANX1 in both normal liver tissues (P = 0.044) and whole blood (P < 0.001) in the GTEx dataset, and PANX1 mRNA expression levels were significantly higher in HCC samples and associated with a poorer survival of HCC patients. However, we did not observe such correlations for APP rs9976425.

CONCLUSIONS

These results indicated that SNPs in the NLRP3 inflammasome-related genes may serve as potential biomarkers for HBV-related HCC survival, once replicated by additional larger studies.

Identification of the differentially expressed activated memory CD4+ T-cells-related genes and ceRNAs in oral lichen planus

Background

Oral lichen planus (OLP) is a common chronic oral mucosal disease with 1.4 % malignant transformation rate, and its etiology especially immune pathogenesis remains unclear. This study was aimed at investigating the immune cells related molecular underlying the pathophysiology of OLP through bioinformatics analysis.

Methods

The dataset GSE52130 obtained from the Gene Expression Omnibus (GEO) database was conducted a comprehensive analysis in this study. The CIBERSORTx was used for investigating immune cells infiltration. The gene set enrichment analysis (GSEA) and gene ontology (GO) enrichment were performed for exploring the biological functions and gene annotation. The protein-protein interactions (PPI) were constructed by STRING database and visualized by Cytoscape software. The cytohubba plugin was utilized for screening hub genes. The receiver operating characteristic (ROC) was performed for evaluating diagnostic value of hub genes. The miRNAs, lncRNAs and drugs were respectively predicted by NetworkAnalyst, miRTarbase, ENCORI, and DGIdb database.

Results

This study identified 595 differentially expressed genes (DEGs). The GSEA indicated keratinization, innate immune system and biological oxidation were involved in OLP. GO analysis showed extracellular matrix and keratinocyte were mainly enriched. And we found the activated memory CD4+ T cells were lowly infiltrated in OLP. We identified 101 activated memory CD4+ T-cells-related DEGs. Three hub genes (APP, IL1B, TF) were selected. APP and IL1B were significantly up-regulated, whereas TF was down-regulated in OLP. The three hub genes show high diagnostic value in OLP. Additionally, they were involved in MAPK signal, NF-kappaB signal and iron metabolism in OLP. What's more, NEAT1/XIST - miR - 15a - 5p/miR - 155-5p - APP/IL1B signal axis was focused in competing endogenous RNA (ceRNA) network. In addition, 35 drugs were predicted for OLP.

Conclusion

Three activated memory CD4+ T-cells-related DEGs were identified by integrative analysis. It may provide novel insight into the pathogenesis of OLP and suggest potential therapeutic targets for OLP.

MiRNAs that target amyloid precursor protein processing machinery in extracellular vesicles and particles derived from oral squamous cells carcinoma

BACKGROUND

Considering that microRNAs (miRNAs), extracellular vesicles and particles (EVPs) and the amyloid precursor protein (APP) processing have been shown to be altered in oral squamous cells carcinoma (OSCC), it is possible that miRNAs that target APP processing pathways in EVPs are impacted in tumor cells. Our aim was to evaluate miRNAs that target APP itself or disintegrin and metalloproteinase domain 10 (ADAM10), which generate a trophic compound, sAPPα, in EVPs derived from OSCC cell lines, an aggressive and non-invasive, compared to normal keratinocytes.

METHODS

We used two OSCC cell lines, an aggressive human oral squamous cell carcinoma cell line (SCC09) and a less aggressive cell line (CAL27) compared with a keratinocyte lineage (HaCaT). Cells were maintained in cell media, from which we isolated EVPs. EVPs were evaluated regarding their size and concentration using Nanotracking Analysis. We measured the levels of miRNAs which had as potential downstream target APP or ADAM10, specifically miR-20a-5p, miR-103a-3p, miR-424-5p, miR-92b-3p, miR-31-5p, and miR-93-5.

RESULTS

There were no differences on size distributions and concentration of isolated EVPs. OSCC cell lines-derived EVPs miR-20a-5p, miR-92b-3p, and miR-93-5p were upregulated in comparison to HaCaT-derived EVPs; while miR-31-5p was reduced in EVPs obtained from CAL27 cells.

CONCLUSION

Our results indicate changes in miRNAs that target APP machinery processing in EVPs derived from OSCC cell lines of different aggressiveness, which may be involved with abnormal miRNA expression in OSCC tissue and/or releasing tumor suppressor miRNA.

Multi-omics identification of an immunogenic cell death-related signature for clear cell renal cell carcinoma in the context of 3P medicine and based on a 101-combination machine learning computational framework

Background

Clear cell renal cell carcinoma (ccRCC) is a prevalent urological malignancy associated with a high mortality rate. The lack of a reliable prognostic biomarker undermines the efficacy of its predictive, preventive, and personalized medicine (PPPM/3PM) approach. Immunogenic cell death (ICD) is a specific type of programmed cell death that is tightly associated with anti-cancer immunity. However, the role of ICD in ccRCC remains unclear.

Methods

Based on AddModuleScore, single-sample gene set enrichment analysis (ssGSEA), and weighted gene co-expression network (WGCNA) analyses, ICD-related genes were screened at both the single-cell and bulk transcriptome levels. We developed a novel machine learning framework that incorporated 10 machine learning algorithms and their 101 combinations to construct a consensus immunogenic cell death-related signature (ICDRS). ICDRS was evaluated in the training, internal validation, and external validation sets. An ICDRS-integrated nomogram was constructed to provide a quantitative tool for predicting prognosis in clinical practice. Multi-omics analysis was performed, including genome, single-cell transcriptome, and bulk transcriptome, to gain a more comprehensive understanding of the prognosis signature. We evaluated the response of risk subgroups to immunotherapy and screened drugs that target specific risk subgroups for personalized medicine. Finally, the expression of ICD-related genes was validated by qRT-PCR.

Results

We identified 131 ICD-related genes at both the single-cell and bulk transcriptome levels, of which 39 were associated with overall survival (OS). A consensus ICDRS was constructed based on a 101-combination machine learning computational framework, demonstrating outstanding performance in predicting prognosis and clinical translation. ICDRS can also be used to predict the occurrence, development, and metastasis of ccRCC. Multivariate analysis verified it as an independent prognostic factor for OS, progression-free survival (PFS), and disease-specific survival (DSS) of ccRCC. The ICDRS-integrated nomogram provided a quantitative tool in clinical practice. Moreover, we observed distinct biological functions, mutation landscapes, and immune cell infiltration in the tumor microenvironment between the high- and low-risk groups. Notably, the immunophenoscore (IPS) score showed a significant difference between risk subgroups, suggesting a better response to immunotherapy in the high-risk group. Potential drugs targeting specific risk subgroups were also identified.

Conclusion

Our study constructed an immunogenic cell death-related signature that can serve as a promising tool for prognosis prediction, targeted prevention, and personalized medicine in ccRCC. Incorporating ICD into the PPPM framework will provide a unique opportunity for clinical intelligence and new management approaches.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13167-023-00327-3.

Single-cell RNA sequencing reveals the heterogeneity and microenvironment in one adenoid cystic carcinoma sample

Adenoid cystic carcinoma (ACC) is one of the most common malignancy of the major salivary glands with a high recurrence rate and poor prognosis. Determining tumor heterogeneity and factors in the microenvironment may provide novel therapeutic targets for ACC. We performed single-cell RNA sequencing of one ACC sample and normal salivary gland tissues from a patient to analyze tumor heterogeneity, immunosuppressive landscape, and intercellular communication networks. The heterogeneity of epithelial cells in ACC tissues was significantly higher compared with that in normal tissues, whereas immune cells were almost absent. We found four malignant cell clusters in ACC and explored their characteristics and function. In tumor tissues, CD8 + cytotoxic T cells and CD4 + T helper cells were significantly decreased, whereas IgA + plasma cells were absent. There were two clusters of macrophages, one representing IL1B macrophages and the other consisted of a cluster of macrophages associated with the epithelial mesenchymal transition (EMT). Both were significantly different from the normal tissue composition. In addition, the communication between epithelial cells and other cells in the tumor tissue was enhanced. MIF-CD74 and APP-CD74 were significantly upregulated. We comprehensively described the heterogeneity of ACC and the tumor microenvironment (TME) from a single cell perspective including cell characteristics, immune cell infiltration, and cell communication. CLINICAL RELEVANCE: This study provided further insights into ACC and may lead to new treatment strategies.

Functions of amyloid precursor protein in metabolic diseases

Amyloid precursor protein (APP) is a transmembrane precursor protein that is widely expressed in the central nervous system and peripheral tissues in the liver and pancreas, adipose tissue, and myotubes. APP can be cleaved by proteases in two different ways to produce a variety of short peptides, each with different physiological properties and functions. APP peptides generated by non-amyloidogenic processing can positively influence metabolism, while the peptides produced by amyloidogenic processing have the opposite effects. Here, we summarize the regulatory effects of APP and its cleavage peptides on metabolism in the central nervous system and peripheral tissues. In addition, abnormal expression and function of APP and APP-derived peptides are associated with metabolic diseases, such as type 2 diabetes, obesity, non-alcoholic fatty liver disease, and cardiovascular disease, and cancers. Pharmacological intervention of APP function or reduction of the production of peptides derived from amyloidogenic processing may be effective strategies for the prevention and treatment of Alzheimer's disease, and they may also provide new guidance for the treatment of metabolic diseases.

Deregulation of extracellular matrix modeling with molecular prognostic markers revealed by transcriptome sequencing and validations in Oral Tongue squamous cell carcinoma

Oral Tongue Squamous Cell Carcinoma (OTSCC), a distinct sub-group of head and neck cancers, is characteristically aggressive in nature with a higher incidence of recurrence and metastasis. Recent advances in therapeutics have not improved patient survival. The phenomenon of occult node metastasis, even among the purportedly good prognosis group of early-stage and node-negative tongue tumors, leads to a high incidence of locoregional failure in OTSCC which needs to be addressed. In the current study, transcriptome analysis of OTSCC patients identified the key genes and deregulated pathways. A panel of 26 marker genes was shortlisted and validated using real-time PCR in a prospective cohort of 100 patients. The gene expression was correlated with clinicopathological features including occult node metastasis, survival, and therapeutic outcome. The up-regulation of a panel of 6 genes namely, matrix metalloproteinase 9 (MMP9), Laminin subunit Gamma 2 (LAMC2), Desmoglein 2 (DSG2), Plasminogen Activator Urokinase (PLAU), Forkhead Box M1 (FOXM1), and Myosin 1B (MYO1B) was associated with failure of treatment in the early stage (T1, T2). Up-regulation of Tenacin C (TNC) and Podoplanin (PDPN) was significantly correlated with occult node positivity. Immunohistochemical analysis of LAMC2, MMP9, and E-Cadherin (ECAD) confirmed these markers to be indicators of poor prognosis. We propose this panel of valuable prognostic markers can be clinically useful to identify poor prognosis and occult node metastasis in OTSCC patients.

Amyloid precursor protein and its phosphorylated form in non-small cell lung carcinoma

Amyloid precursor protein (APP) is a well-known to be involved in the development of Alzheimer's disease and harbors several phosphorylation sites in its cytoplasmic domain. APP has been also proposed as one of the molecules involved in cell proliferation and invasion in several human malignancies. However, the roles of APP including its phosphorylated form (p-APP) have remained largely unexplored in non-small cell lung carcinoma (NSCLC). Therefore, in this study, we first examined both APP and p-APP expressions and then explored the association between p-APP/APP status and clicopathological parameters in NSCLC. The number of APP-positive cases was 24/91 (26%) in adenocarcinomas (Ad) and 16/35 (46%) in squamous cell carcinomas (Sq), respectively. p-APP-positive cases in Ad and Sq were 28 (31%) and 17 (49%), respectively. In Ad cases, both APP and p-APP were significantly associated with clinical stages (APP and p-APP), pathologic T (p-APP), and pathologic N (APP and p-APP) of the cases examined. In Sq cases, there were no significant associations between APP status and any of the clinicopathological parameters examined with an exception of the significant correlation of p-APP with lymphatic invasion. APP status was not significantly associated with overall survival (OS) of Ad patients but a significant association was detected between p-APP-positive cases and OS of these patients (p < 0.0001). In Sq cases, both APP- (p = 0.01) and p-APP-positive (p = 0.04) groups were also significantly associated with adverse clinical outcome. These results did firstly demonstrate that APP, in particular, p-APP, is considered a potent prognostic factor for both Ad and Sq lung carcinoma patients. However, APP signaling including its phosphorylation signal are considered different between these two types of NSCC cells and further investigations are required for clarification.

Amyloid β precursor protein silencing attenuates epithelial‑mesenchymal transition of nasopharyngeal carcinoma cells via inhibition of the MAPK pathway

Advances in the treatment of nasopharyngeal carcinoma (NPC) have significantly improved the local control rate; however, distant metastasis remains a principal cause of mortality. Previous studies have demonstrated that the expression levels of amyloid β precursor protein (APP) are increased in NPC. The present study aimed to investigate the association between APP and the development of NPC. In order to knockdown APP expression, an APP-small interfering RNA vector was synthesized and transfected into SUNE-1 cells. Cell Counting Kit-8 assay was performed to assess cell viability. The migratory and invasive abilities of SUNE-1 cells were examined by wound healing and Transwell assays, respectively. Reverse transcription-quantitative polymerase chain reaction and western blotting were performed to measure the mRNA and protein expression levels of APP, and additional factors involved in epithelial-mesenchymal transition (EMT) and in the mitogen-activated protein kinase (MAPK) signaling pathway. APP silencing significantly suppressed cell viability, migration and invasion. In addition, APP interference downregulated the expression levels of metastasis-associated 1, matrix metalloproteinase (MMP)-2 and MMP-9; however, knockdown of APP led to upregulation of tissue inhibitor of metalloproteinases 2 and inhibited EMT. The phosphorylation levels of p38, extracellular signal-regulated kinases 1/2 and c-Jun N-terminal kinases 1/2 were decreased following downregulation of APP. The present results suggested that APP knockdown may significantly inhibit the development of NPC by suppressing cell viability, migration and invasion, and by inhibiting the EMT process via downregulation of the MAPK signaling pathway. Therefore, APP may facilitate the development of a novel gene therapy for the treatment of NPC.

The amyloid precursor protein (APP) processing as a biological link between Alzheimer's disease and cancer

Aging is a risk factor for several illnesses, such as Alzheimer's Disease and various cancers. However, an inverse correlation between malignancies and Alzheimer's Disease has been suggested. This review addressed the potential role of non-amyloidogenic and amyloidogenic pathways of amyloid precursor protein processing as a relevant biochemical mechanism to clarify this association. Amyloidogenic and non-amyloidogenic pathways have been related to Alzheimer's Disease and certain malignancies, respectively. Several known molecules involved in APP processing, including its regulation and final products, were summarized. Among them some candidate mechanisms emerged, such as extracellular-regulated kinase (Erk) and protein kinase C (PKC). Therefore, the imbalance of APP processing may be involved with the negative correlation between cancer and Alzheimer Disease.

Amyloid Precursor Protein Is Associated with Aggressive Behavior in Nonluminal Breast Cancers

BACKGROUND

β-amyloid precursor protein (APP), a potential target for Alzheimer's disease treatment, has recently been shown to take part in carcinogenesis. Increased APP promotes migration, survival, and proliferation in breast cancer cell lines. We examined the clinical value of APP in breast cancers. A comprehensive examination of clinicopathological features related to APP expression in a large cohort of breast cancers and the corresponding metastatic lymph nodes was performed. APP expression and its prognostic impact in different breast cancer subtypes were examined.

RESULTS

APP was highly expressed in nonluminal breast cancers and correlated with features associated with nonluminal breast cancers (including higher grade, the presence of necrosis, and higher proliferative index, growth factor receptor, and basal marker expression). Multivariate Cox hazard analysis demonstrated that APP was an independent adverse prognostic factor of disease-free survival (DFS; hazard ratio [HR], 2.090; p = .013; 95% confidence interval [CI], 1.165-3.748) and breast cancer-specific survival (BCSS; HR, 2.631; p = .002; 95% CI, 1.408-4.915) in the nonluminal group. The independent prognostic impact was also seen in triple negative breast cancers. Interestingly, a higher expression of APP was found in nodal metastasis compared with primary tumor. Such APP upregulation was correlated with further distal metastasis and poorer outcome (DFS: log-rank, 12.848; p < .001; BCSS: log-rank, 13.947; p < .001).

CONCLUSION

Our findings provided evidence of oncogenic roles of APP in clinical breast cancers. Patients with positive APP expression, particularly those with APP upregulation in lymph node metastases, may require vigilant monitoring of their disease and more aggressive therapy.

IMPLICATIONS FOR PRACTICE

β-amyloid precursor protein (APP), a potential target for Alzheimer's disease, has recently been implicated in oncogenesis. Here, evidence of its roles in clinical breast cancers is provided. Positive APP expression was found to be an independent prognostic factor in nonluminal cancers, particularly triple negative breast cancers (TNBCs). Interestingly, a higher APP in nodal metastases was associated with distal metastases. TNBCs are heterogeneous and currently have no available target therapy. APP could have therapeutic potential and be used to define the more aggressive cases in TNBCs. Current prognostic analysis is based on primary tumor. The present data suggest that investigation of nodal metastases could provide additional prognostic value.

Identification of Key Genes and Pathways in Tongue Squamous Cell Carcinoma Using Bioinformatics Analysis

BACKGROUND Tongue squamous cell carcinoma (TSCC) is a major type of oral cancers and has remained an intractable cancer over the past decades. The aim of this study was to identify differentially expressed genes (DEGs) during TSCC and reveal their potential mechanisms. MATERIAL AND METHODS The gene expression profiles of GSE13601 were downloaded from the GEO database. The GSE13601 dataset contains 57 samples, including 31 tongue SCC samples and 26 matched normal mucosa samples. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes pathway (KEGG) enrichment analyses were performed; Cytoscape software was used for the protein-protein interaction (PPI) network and module analysis of the DEGs. RESULTS We identified a total of 1,050 upregulated DEGs (uDEGs) and 702 downregulated DEGs (dDEGs) of TSCC. The GO analysis results showed that uDEGs were significantly enriched in the following biological processes (BP): signal transduction, positive or negative regulation of cell proliferation, and negative regulation of cell proliferation. The dDEGs were significantly enriched in the following biological processes: signal transduction, cell adhesion, and apoptotic process. The KEGG pathway analysis showed that uDEGs were enriched in metabolic pathways, pathways in cancer, and PI3K-Akt signaling pathway, while the dDEGs were enriched in focal adhesion and ECM-receptor interaction. The top centrality hub genes RAC1, APP, EGFR, KNG1, AGT, and HRAS were identified from the PPI network. Module analysis revealed that TSCC was associated with significant pathways, including neuroactive ligand-receptor interaction, calcium signaling pathway, and chemokine signaling pathway. CONCLUSIONS The present study identified key genes and signal pathways, which deepen our understanding of the molecular mechanisms of carcinogenesis and development of the disease, and might be used as diagnostic and therapeutic molecular biomarkers for TSCC.

Amyloid precursor protein has clinical and prognostic significance in AML1-ETO-positive acute myeloid leukemia

Amyloid precursor protein (APP) has been reported to be highly expressed in acute myeloid leukemia (AML)1-eight-twenty one (ETO)-positive AML. In the present study, the clinical and prognostic significance of APP expression was assessed in 65 patients with AML1-ETO-positive AML using reverse transcription-quantitative polymerase chain reaction. The patients were divided into an APP-high expression (APP-H) group (n=32) and an APP-low expression (APP-L) group (n=33) according to the cut-off value of APP relative expression, which was calculated by receiver operating characteristic curve analysis. It was observed that C-KIT mutations (14/32 vs. 3/33, P=0.009), white blood cell count (median, 23.2×10⁹ vs. 12.4×10⁹ cells/l; P=0.011) and bone marrow cellularity (median, 91.0 vs. 84.0%; P=0.039) and incidence of extramedullary leukemia (11/32 vs. 3/33, P=0.013) were all significantly increased in the APP-H group compared with the APP-L group. Furthermore, significantly lower rate of cumulative two-cycle complete remission (83.9 vs. 100%, P=0.016), major molecular remission following two courses of consolidation (34.5 vs. 71.4%, P=0.005), and poorer relapse-free survival (RFS) (33.5±5.2% vs. 76.3±6.9%, P<0.001) and overall survival (OS) (44.5±7.0% vs. 81.9±5.8%, P=0.002) were associated with APP overexpression. Multivariate analysis revealed that APP overexpression was a significant adverse factor affecting both RFS and OS. Taken together, these data suggest that APP may be correlated with C-KIT mutations and involved in leukemia cell proliferation, and its overexpression has an adverse effect on the prognosis in AML1-ETO-positive AML.

A seven-gene prognostic signature for rapid determination of head and neck squamous cell carcinoma survival

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer and displays divergent clinical outcomes. Prognostic biomarkers might improve risk stratification and survival prediction. We aimed to investigate the prognostic genes associated with overall survival. A two-step gene selection method was used to develop a seven-gene-based prognostic model based on the training set collected from The Cancer Genome Atlas (TCGA). In addition, the prognostic model was validated in an independent testing set from Gene Expression Omnibus (GEO). The score based on the model successfully distinguished HNSCC survival into high-risk and low-risk groups in the training set (HR, 2.79; 95% CI, 1.98–3.92; P=4.05×10⁻⁹) and the testing set (HR, 2.05; 95% CI, 1.35–3.11; P=7.98×10⁻⁴). In addition, the score could significantly predict 5-year survival by ROC curves (AUCs for training set, 0.73; testing set, 0.66). Combining risk scores with clinical characteristics improved the AUCs beyond using clinical characteristics alone (training set, from 0.57 to 0.75; testing set, from 0.63 to 0.72). A subgroup sensitivity analysis with HPV status and tumor sites revealed that the risk score was significant in all subgroups except oral cavity tumors of the testing set. Furthermore, HPV-positive status improves survival in oropharyngeal HNSCC but not non-oropharyngeal HNSCC. In conclusion, the seven-gene prognostic signature is a reliable and practical prognostic tool for HNSCC. This approach can add prognostic value to clinical characteristics and provides a new possibility for individualized treatment.

Identification of potential biomarkers and analysis of prognostic values in head and neck squamous cell carcinoma by bioinformatics analysis

The purpose of this study was to find disease-associated genes and potential mechanisms in head and neck squamous cell carcinoma (HNSCC) with deoxyribonucleic acid microarrays. The gene expression profiles of GSE6791 were downloaded from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) were obtained with packages in R language and STRING constructed protein–protein interaction (PPI) network of the DEGs with combined score >0.8. Subsequently, module analysis of the PPI network was performed by Molecular Complex Detection plugin and functions and pathways of the hub gene in subnetwork were studied. Finally, overall survival analysis of hub genes was verified in TCGA HNSCC cohort. A total of 811 DEGs were obtained, which were mainly enriched in the terms related to extracellular matrix (ECM)–receptor interaction, ECM structural constituent, and ECM organization. A PPI network was constructed, consisting of 401 nodes and 1,254 edges and 15 hub genes with high degrees in the network. High expression of 4 genes of the 15 genes was associated with poor OS of patients in HNSCC, including PSMA7, ITGA6, ITGB4, and APP. Two significant modules were detected from the PPI network, and the enriched functions and pathways included proteasome, ECM organization, and ECM–receptor interaction. In conclusion, we propose that PSMA7, ITGA6, ITGB4, and APP may be further explored as potential biomarkers to aid HNSCC diagnosis and treatment.

Fendiline inhibits proliferation and invasion of pancreatic cancer cells by interfering with ADAM10 activation and β-catenin signaling

ADAM10 (A Disintegrin and Metalloprotease Domain 10) affects the pathophysiology of various cancers, and we had shown that inhibition of ADAM10 sensitizes pancreatic cancer cells to gemcitabine. ADAM10 is activated in response to calcium influx, and here we examined if calcium channel blockers (CCB) would impede ADAM10 activation and affect biology of pancreatic cancer cells. We find that the CCB, fendiline, significantly reduces proliferation, migration, invasion, and anchorage independent growth of pancreatic cancer cells. This was associated with ADAM10 inhibition and its localization at the actin-rich membrane protrusions. Further, fendiline-treated cells formed cadherin-catenin positive tight adherens junctions and elicited defective protein trafficking and recycling. Furthermore, the expression of β-catenin target genes, cyclinD1, c-Myc and CD44, were significantly decreased, suggesting that fendiline might prevent cell proliferation and migration by inhibiting ADAM10 function, cadherin proteolysis and stabilization of cadherin-catenin interaction at the plasma membrane. This will subsequently diminish β-catenin intracellular signaling and repress TCF/LEF target gene expression. Supporting this notion, RNAi-directed downregulation of ADAM10 in cancer cells decreased the expression of cyclinD1, c-Myc and CD44. Furthermore, analysis of human pancreatic tumor tissue microarrays and lysates showed elevated levels of ADAM10, suggesting that aberrant activation of ADAM10 plays a fundamental role in growth and metastasis of PDACs and inhibiting this pathway might be a viable strategy to combat PDACs.

Overexpression of Histone Deacetylase and Amyloid Precursor Protein in Hepatocellular Carcinoma

Epigenetic modifications are involved in the pathogenesis of cancer, and histone deacetylase inhibitors are considered potential therapeutic agents. Histone tails undergo acetylation at lysine residues, which is associated with transcriptional activation. However, previous studies indicated that as histone deacetylase inhibitors, both (-)-epigallocatechin-3-gallate and valproic acid presented the effects of downregulation of amyloid precursor protein expression, which resulted in the induction of apoptosis. The downregulation of amyloid precursor protein, instead of conventionally activating gene expression as histone deacetylase inhibitor, was attractive. However, there was no relevant report on the correlation of the expression of amyloid precursor protein and histone deacetylase 1 in cancer. In the present study, we detected the expression of amyloid precursor protein and histone deacetylase 1 in hepatocellular carcinoma and adjacent tissues, as well as the correlations among histone deacetylase 1, amyloid precursor protein, and tumor stage. The results showed that the expressions of amyloid precursor protein and histone deacetylase 1 were significantly higher in hepatocellular carcinoma tissues than that in adjacent tissues ( P < .05), however, there was no statistical difference between amyloid precursor protein and histone deacetylase 1 with tumor stages. The present findings provided more foundation for the study on amyloid precursor protein metabolism in cancer, especially on the regulation of amyloid precursor protein by histone deacetylases.

Amyloid precursor protein cooperates with c-KIT mutation/overexpression to regulate cell apoptosis in AML1-ETO-positive leukemia via the PI3K/AKT signaling pathway

It has been reported that amyloid precursor protein (APP) promotes cell proliferation and metastasis in various types of solid cancers. In our previous study, we showed that APP is highly expressed and regulates leukemia cell migration in AML1‑ETO-positive (AE) leukemia. Whether APP is involved in the regulation of AE leukemia cell proliferation or apoptosis is unclear. In the present study we focused on the correlation of APP with c-KIT mutation/overexpression and cell proliferation and apoptosis in AE leukemia. APP and c-KIT expression detected by quantitative real-time (qPCR) method, and c-KIT mutations screened using PCR in bone marrow cells from 65 patients with AE leukemia before their first chemotherapy, were simultaneously assessed. Furthermore, the Kasumi-1 cell line was chosen as the cell model, and the APP gene was knocked down using siRNA technology. The correlation of cell cycle distribution and apoptosis and c-Kit expression with APP expression levels, as well as the regulation of the PI3K/AKT signaling pathway by APP were analyzed in the Kasumi-1 cell line. The results showed that peripheral white blood cell counts (P=0.008) and bone marrow cellularity (P=0.031), but not bone marrow blasts, were correlated with APP expression. Moreover, the patients with APP high expression had a significantly higher incidence of c-KIT mutations (P<0.001) and increased levels of c-KIT expression (P=0.001) and poorer disease outcome. In the Kasumi-1 cell line, as compared with the wild-type and negative control cells, cell apoptosis, both early (P<0.001) and late (P<0.001), was significantly increased when the APP gene was knocked down, concomitant with reduced levels of anti-apoptotic protein Bcl-2 and increased levels of caspase-3 and -9, however, no apparent change was observed in the cell cycle distribution (P>0.05). Moreover, the knockdown of APP markedly decreased c-KIT expression at both the transcription (as evidenced by qPCR analysis) and translation (as confirmed by CD117 assay and western blot analysis) levels, as well as p-AKT and its downstream targets including NF-κB, p53 and Bcl-2. In conclusion, APP may cooperate with c-KIT mutation/overexpression in the regulation of cell apoptosis but not proliferation in AE leukemia via the PI3K/AKT signaling pathway.

Suppression of antioxidant Nrf-2 and downstream pathway in H9c2 cells by advanced glycation end products (AGEs) via ERK phosphorylation

Diabetic cardiomyopathy is related to oxidative stress and correlated with the presence of advanced glycation end products (AGEs). In a clinical setting, AGEs can be detected in patients presenting diabetic cardiomyopathy; however, the underlying mechanism has yet to be elucidated. In our previous study, AGEs increase cell hypertrophy via ERK phosphorylation in a process closely related to ROS production. Thus, we propose that AGEs regulate the antioxidant gene nuclear factor-erythroid 2-related factor (Nrf-2). In H9c2 cells treated with AGEs, the expression of Nrf-2 was reduced; however, ERK phosphorylation was shown to increase. Treatment with H2O2 was also shown to increase Nrf-2 and ERK phosphorylation. In cells pretreatment with ROS scavenger NAC, the effects of H2O2 were reduced; however, the effects of the AGEs remained largely unchanged. Conversely, when cells were pretreated with PD98059 (ERK inhibitor), the expression of Nrf-2 was recovered following treatment with AGEs. Our results suggest that AGEs inhibit Nrf-2 via the ERK pathway; however, this influence is partly associated with ROS. Our finding further indicated that AGEs possess both ROS-dependent and ROS-independent pathways, resulting in a reduction in Nrf-2. This report reveals an important mechanism underlying the regulation of diabetic cardiomyopathy progression by AGEs.

Alternative splicing of VEGFA, APP and NUMB genes in colorectal cancer

AIM

To investigate alternative splicing in vascular endothelial growth factor A (VEGFA), amyloid beta precursor protein (APP), and Numb homolog (NUMB) in colorectal cancer (CRC).

METHODS

Real-time quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) and PCR-restriction fragment length polymorphism analyses were performed to detect the expression of VEGFA, APP, and NUMB mRNA in 20 CRC tissues and matched adjacent normal tissues, as well as their alternative splicing variants.

RESULTS

qRT-PCR analysis revealed that the expression of APP, NUMB, and VEGFA165b mRNA were significantly downregulated, while VEGFA mRNA was upregulated, in CRC tissues (all P < 0.05). PCR-restriction fragment length polymorphism analysis revealed that the expression of VEGFA165a/b in CRC tissues was significantly higher than in adjacent normal tissues (P < 0.05). Compared with adjacent normal tissues, the expression of NUMB-PRR(S) in CRC tissues was significantly decreased (P < 0.05), and the expression of NUMB-PRR(L) was increased (P < 0.05).

CONCLUSION

Alternative splicing of VEGFA, APP, and NUMB may regulate the development of CRC, and represent new targets for its diagnosis, prognosis, and treatment.

Non-invasive screening for Alzheimer's disease by sensing salivary sugar using Drosophila cells expressing gustatory receptor (Gr5a) immobilized on an extended gate ion-sensitive field-effect transistor (EG-ISFET) biosensor

Body fluids are often used as specimens for medical diagnosis. With the advent of advanced analytical techniques in biotechnology, the diagnostic potential of saliva has been the focus of many studies. We recently reported the presence of excess salivary sugars, in patients with Alzheimer’s disease (AD). In the present study, we developed a highly sensitive, cell-based biosensor to detect trehalose levels in patient saliva. The developed biosensor relies on the overexpression of sugar sensitive gustatory receptors (Gr5a) in Drosophila cells to detect the salivary trehalose. The cell-based biosensor was built on the foundation of an improved extended gate ion-sensitive field-effect transistor (EG-ISFET). Using an EG-ISFET, instead of a traditional ion-sensitive field-effect transistor (ISFET), resulted in an increase in the sensitivity and reliability of detection. The biosensor was designed with the gate terminals segregated from the conventional ISFET device. This design allows the construction of an independent reference and sensing region for simultaneous and accurate measurements of samples from controls and patients respectively. To investigate the efficacy of the cell-based biosensor for AD screening, we collected 20 saliva samples from each of the following groups: participants diagnosed with AD, participants diagnosed with Parkinson’s disease (PD), and a control group composed of healthy individuals. We then studied the response generated from the interaction of the salivary trehalose of the saliva samples and the Gr5a in the immobilized cells on an EG-ISFET sensor. The cell-based biosensor significantly distinguished salivary sugar, trehalose of the AD group from the PD and control groups. Based on these findings, we propose that salivary trehalose, might be a potential biomarker for AD and could be detected using our cell-based EG-ISFET biosensor. The cell-based EG-ISFET biosensor provides a sensitive and direct approach for salivary sugar detection and may be used in the future as a screening method for AD.

(-)-Epigallocatechin-3-gallate induces cancer cell apoptosis via acetylation of amyloid precursor protein

Epigenetic modifications are involved in cancer pathogenesis, and HDACis are considered potential therapeutic agents. We and others have shown the inhibitory activity of EGCG on HDAC1. But little is known about the effect of EGCG as on epigenetic regulation in cancer. Here, we try to demonstrate that EGCG acts as an HDACi downregulated APP expression, which was pathophysiologically upregulated in cancers and exerts a key role in cancer cell growth. We used PC-12 cells, SK-N-SH cells and primary tumor tissues for our analysis. Male 4-week-old athymic nude mice were used for heterotopic tumor growth assay. We employed Western blotting analysis to detect Bcl-2, Bax, APP, caspase-3, caspase-7, HDAC1 and H4Ac. We used AnnexinV-FITC and TUNEL staining for apoptosis detection. Tumor tissues were examined by immunohistochemical staining. We demonstrated that EGCG suppresses the growth of xenografted adrenal pheochromocytoma. Flow cytometry analysis and TUNEL staining showed that EGCG induced the apoptosis. Treatment with EGCG resulted in decrease in Bcl-2 but increase in Bax and activated caspase-3 and caspase-7. HDAC inhibitor EGCG leaded to hyperacetylated histone H4 by immunofluorescence. EGCG decreased APP levels by immunofluorescence staining and Western blot analysis. Silencing specific to HDAC1 leaded to caspase-3 and caspase-7 activation and cleavage. Our results are the first to demonstrate a functional interaction between EGCG and APP in suppression tumor growth, and provide a new epigenetic effects of EGCG on antitumor.

The E1 copper binding domain of full-length amyloid precursor protein mitigates copper-induced growth inhibition in brain metastatic prostate cancer DU145 cells

Copper plays an important role in the aetiology and growth of tumours and levels of the metal are increased in the serum and tumour tissue of patients affected by a range of cancers including prostate cancer (PCa). The molecular mechanisms that enable cancer cells to proliferate in the presence of elevated copper levels are, therefore, of key importance in our understanding of tumour growth progression. In the current study, we have examined the role played by the amyloid precursor protein (APP) in mitigating copper-induced growth inhibition of the PCa cell line, DU145. A range of APP molecular constructs were stably over-expressed in DU145 cells and their effects on cell proliferation in the presence of copper were monitored. Our results show that endogenous APP expression was induced by sub-toxic copper concentrations in DU145 cells and over-expression of the wild-type protein was able to mitigate copper-induced growth inhibition via a mechanism involving the cytosolic and E1 copper binding domains of the full-length protein. APP likely represents one of a range of copper binding proteins that PCa cells employ in order to ensure efficient proliferation despite elevated concentrations of the metal within the tumour microenvironment. Targeting the expression of such proteins may contribute to therapeutic strategies for the treatment of cancers.

Circulating miRNAs as biomarkers for neurodegenerative disorders

Neurodegenerative disorders, such as Alzheimer’s disease (AD), Parkinson’s disease (PD) and frontotemporal dementias (FTD), are considered distinct entities, however, there is increasing evidence of an overlap from the clinical, pathological and genetic points of view. All neurodegenerative diseases are characterized by neuronal loss and death in specific areas of the brain, for example, hippocampus and cortex for AD, midbrain for PD, frontal and temporal lobes for FTD. Loss of neurons is a relatively late event in the progression of neurodegenerative diseases that is typically preceded by other events such as metabolic changes, synaptic dysfunction and loss, neurite retraction, and the appearance of other abnormalities, such as axonal transport defects. The brain’s ability to compensate for these dysfunctions occurs over a long period of time and results in late clinical manifestation of symptoms, when successful pharmacological intervention is no longer feasible. Currently, diagnosis of AD, PD and different forms of dementia is based primarily on analysis of the patient’s cognitive function. It is therefore important to find non-invasive diagnostic methods useful to detect neurodegenerative diseases during early, preferably asymptomatic stages, when a pharmacological intervention is still possible. Altered expression of microRNAs (miRNAs) in many disease states, including neurodegeneration, and increasing relevance of miRNAs in biofluids in different pathologies has prompted the study of their possible application as neurodegenerative diseases biomarkers in order to identify new therapeutic targets. Here, we review what is known about the role of miRNAs in the pathogenesis of neurodegeneration and the possibilities and challenges of using these small RNA molecules as a signature for neurodegenerative conditions.

Soluble amyloid precursor protein-α rescues age-linked decline in neural progenitor cell proliferation

Neurogenesis is thought to play a role in cognitive function and hippocampal plasticity. Previous studies suggest that neurogenesis declines with aging. However, the onset and mechanism of declined neurogenesis are not fully elucidated. Here we show that the major decline in neurogenesis takes place during adulthood, before aging. Decline in neurogenesis takes place in the subgranular layer of the dentate gyrus and in the subventricular zone, and is primarily due to a reduced number of fast-proliferating neural progenitor cells. Importantly, this decline can be rescued by intraventricular injection of recombinant soluble amyloid precursor protein (sAPPα), which regulates neural progenitor cell proliferation in the adult brain. The counterpart, sAPPβ, a product of the amyloidogenic cleavage pathway of amyloid precursor protein, fails to exhibit a proliferative effect in vitro and in vivo, in equimolar concentrations to sAPPα. These observations suggest that adulthood is an appropriate time window for an intervention that upregulates neurogenesis, such as enhancement of sAPPα levels, for the prevention of declining brain plasticity and cognitive function.

Amyloid precursor protein in human breast cancer: an androgen-induced gene associated with cell proliferation

Amyloid precursor protein (APP) is a transmembrane protein that is highly expressed in brain tissue. Recently, APP has been implicated in some human malignancies, and its regulation by androgens has also been demonstrated. Such findings suggest the importance of APP in hormone-dependent breast carcinoma, but APP has not yet been examined in breast carcinoma tissues. Therefore, in this study, we examined the biological and clinical significance of APP in breast carcinoma using immunohistochemistry and in vitro studies. APP immunoreactivity was detected in 57 out of 117 (49%) breast carcinoma tissues examined, and it was positively associated with androgen receptor (AR) expression. APP immunoreactivity was also significantly associated with Ki-67 LI and increased risk of recurrence in the estrogen receptor (ER)-positive cases, and was an independent prognostic factor in these patients. Subsequent in vitro experiments demonstrated that APP mRNA expression was significantly induced by biologically active androgen dihydrotestosterone in both a dose-dependent and a time-dependent manner in MCF-7 breast carcinoma cells, which was potently suppressed by an AR blocker hydroxyflutamide. Moreover, cell proliferation activity of MCF-7 and MDA-MB-231 cells was significantly associated with their APP expression level. These findings suggest that APP is an androgen-induced gene that promotes proliferation activity of breast carcinoma cells. Moreover, APP immunohistochemical status is considered a potent prognostic factor in ER-positive breast cancer patients.

WWP1 gene is a potential molecular target of human oral cancer

OBJECTIVE

This study investigates the oncogenic role of WWP1, an ubiquitin ligase linked to tumor promotion, in oral cancer.

STUDY DESIGN

An array-based comparative genomic hybridization was used to detect chromosomal changes in 10 oral cancer specimens. An additional 59 specimens and 6 cultured oral cancer cells were further examined to evaluate changes in the DNA copy number and messenger RNA (mRNA) and protein expression of WWP1.

RESULTS

The copy number of the WWP1 gene and its mRNA levels were significantly increased in the oral cancer specimens. An elevated WWP1 gene expression was observed in 6 cultured oral cancer cell lines. Knockdown of the endogenous WWP1 using small hairpin RNA further showed that deficiency of WWP1 suppressed cell growth and caused apoptosis in oral cancer cells.

CONCLUSION

Our results reveal that WWP1 might play an oncogenic role in oral cancer cells.

Clinical significance of amyloid precursor protein in patients with testicular germ cell tumor

Introduction. The biological role of amyloid precursor protein (APP) is not well understood, especially in testicular germ cell tumors (TGCTs). Therefore, we aimed to investigate the immunoreactivity (IR) and expression of APP in TGCTs and evaluated its clinical relevance. Materials and Methods. We performed an analysis of immunohistochemistry and mRNA expression of APP in 64 testicular specimens and 21 snap-frozen samples obtained from 1985 to 2004. We then evaluated the association between APP expression and clinicopathological status in TGCTs. Results. Positive APP IR was observed in 9.8% (4/41) of seminomatous germ cell tumors (SGCTs) and 39.1% (9/23) of nonseminomatous germ cell tumors (NGCTs). NGCTs showed significantly more cases of positive IR (P = 0.00870) and a higher mRNA expression level compared with those of SGCTs (P = 0.0140). Positive APP IR was also significantly associated with α-fetoprotein (αFP) elevation (P = 0.00870) and venous invasion (P = 0.0414). Conclusion. We observed an elevated APP expression in TGCTs, especially in NGCTs. APP may be associated with a more aggressive cancer in TGCTs.

PuF, an antimetastatic and developmental signaling protein, interacts with the Alzheimer's amyloid-β precursor protein via a tissue-specific proximal regulatory element (PRE)

BACKGROUND

Alzheimer's disease (AD) is intimately tied to amyloid-β (Aβ) peptide. Extraneuronal brain plaques consisting primarily of Aβ aggregates are a hallmark of AD. Intraneuronal Aβ subunits are strongly implicated in disease progression. Protein sequence mutations of the Aβ precursor protein (APP) account for a small proportion of AD cases, suggesting that regulation of the associated gene (APP) may play a more important role in AD etiology. The APP promoter possesses a novel 30 nucleotide sequence, or "proximal regulatory element" (PRE), at -76/-47, from the +1 transcription start site that confers cell type specificity. This PRE contains sequences that make it vulnerable to epigenetic modification and may present a viable target for drug studies. We examined PRE-nuclear protein interaction by gel electrophoretic mobility shift assay (EMSA) and PRE mutant EMSA. This was followed by functional studies of PRE mutant/reporter gene fusion clones.

RESULTS

EMSA probed with the PRE showed DNA-protein interaction in multiple nuclear extracts and in human brain tissue nuclear extract in a tissue-type specific manner. We identified transcription factors that are likely to bind the PRE, using competition gel shift and gel supershift: Activator protein 2 (AP2), nm23 nucleoside diphosphate kinase/metastatic inhibitory protein (PuF), and specificity protein 1 (SP1). These sites crossed a known single nucleotide polymorphism (SNP). EMSA with PRE mutants and promoter/reporter clone transfection analysis further implicated PuF in cells and extracts. Functional assays of mutant/reporter clone transfections were evaluated by ELISA of reporter protein levels. EMSA and ELISA results correlated by meta-analysis.

CONCLUSIONS

We propose that PuF may regulate the APP gene promoter and that AD risk may be increased by interference with PuF regulation at the PRE. PuF is targeted by calcium/calmodulin-dependent protein kinase II inhibitor 1, which also interacts with the integrins. These proteins are connected to vital cellular and neurological functions. In addition, the transcription factor PuF is a known inhibitor of metastasis and regulates cell growth during development. Given that APP is a known cell adhesion protein and ferroxidase, this suggests biochemical links among cell signaling, the cell cycle, iron metabolism in cancer, and AD in the context of overall aging.

Overexpression of amyloid precursor protein in acute myeloid leukemia enhances extramedullary infiltration by MMP-2

It is known that leukemia patients with extramedullary infiltration (EMI) have a worse prognosis than patients without it. Recent data indicate that the amyloid precursor protein (APP) is involved in cell adhesion, motility, and proliferation. The expression of APP and its prognostic significance in acute myeloid leukemia (AML) have not been studied. Our study shows that AML/ETO(+) leukemia patients that overexpress APP easily get EMI and that their long-term survival rate is lower than patients without overexpression of APP. In an in vitro study, we knocked down APP in Kasumi-1 cells using small interfering RNA (siRNA). Transwell data show that siRNA/APP substantially impairs cell migration, but it does not inhibit cell proliferation. Furthermore, by quantitative real-time polymerase chain reaction and Western blot, we found that siRNA/APP decreases MMP-2 expression in vitro. Our study provides a novel clue that APP is involved in the extramedullary infiltration of leukemia by MMP-2.

All in the Family: How the APPs Regulate Neurogenesis

Recent intriguing evidence suggests that metabolites of amyloid precursor protein (APP), mutated in familial forms of Alzheimer’s disease (AD), play critical roles in developmental and postnatal neurogenesis. Of note is soluble APPα (sAPPα) that regulates neural progenitor cell proliferation. The APP family encompasses a group of ubiquitously expressed and evolutionarily conserved, type I transmembrane glycoproteins, whose functions have yet to be fully elucidated. APP can undergo proteolytic cleavage by mutually exclusive pathways. The subtle structural differences between metabolites generated in the different pathways, as well as their equilibrium, may be crucial for neuronal function. The implications of this new body of evidence are significant. Miscleavage of APP would readily impact developmental and postnatal neurogenesis, which might contribute to cognitive deficits characterizing Alzheimer’s disease. This review will discuss the implications of the role of the APP family in neurogenesis for neuronal development, cognitive function, and brain disorders that compromise learning and memory, such as AD.

Amyloid precursor protein as a potential marker of malignancy and prognosis in papillary thyroid carcinoma

Papillary thyroid carcinoma (PTC) is the most common carcinoma of the thyroid gland and has a relatively favorable prognosis. However, it is important to identify PTC characteristics that indicate a high risk for recurrence and metastasis. Recent data indicate that the amyloid precursor protein (APP) is involved in cell adhesion, motility and proliferation. At present, the expression levels of APP and their prognostic significance in PTC have not been studied. In the present study, the APP gene expression in 10 PTCs and their adjacent thyroid tissue samples was analyzed using quantitative real time-PCR. Tissue array blocks were obtained from 90 PTC cases. Tumor regions and their adjacent non-tumor regions were analyzed in tissue array blocks and immunohistochemistry was conducted using sectioned slides. Semi-quantitative scores were correlated with the clinicopathological factors of 90 PTC patients. APP-specific mRNA was increased 50-fold in PTC samples compared with their adjacent thyroid tissue. The immunohistochemistry results showed APP expression levels to be significantly increased in PTC samples compared with their adjacent non-tumor thyroid tissue (p<0.001). High APP scores were significantly correlated with large tumor size, extracapsular invasion and lymph node metastasis. The amyloid precursor protein was overexpressed in PTC and a high APP expression was associated with high malignant potential. Therefore, APP may serve as a prognostic marker and potential novel therapeutic target in PTC.

Regulation of major histocompatibility complex class I molecule expression on cancer cells by amyloid precursor-like protein 2

The three members of the amyloid precursor protein family in mammals [amyloid precursor protein, amyloid precursor-like protein 1, and amyloid precursor-like protein 2 (APLP2)] have been implicated in a large array of intracellular processes, which include development, transcription, apoptosis, metabolism, and the cell cycle. A series of studies by our laboratories has demonstrated that APLP2 is highly expressed by many cancer cell lines (with the highest expression in pancreatic cancer cell lines) and that it facilitates major histocompatibility complex (MHC) class I molecule endocytosis. This review focuses on this recently revealed function of APLP2 relevant to tumor immunology: that it acts as a novel regulator of MHC class I molecule surface expression.

Integrating multiple microarray datasets on oral squamous cell carcinoma to reveal dysregulated networks

BACKGROUND

Oral squamous cell carcinoma (OSCC) is the sixth most common type of carcinoma worldwide. The pathogenic pathways involved in this cancer are mostly unknown; therefore, a better characterization of the OSCC gene expression profile would represent a considerable advance. The public availability of gene expression datasets was meant to obtain new insights on biological processes.

METHODS

We integrated 4 public microarray datasets on OSCC to evaluate the degree of consistency among the biological results obtained in these different studies and to identify common regulatory pathways that could be responsible for tumor growth.

RESULTS

Twelve altered cellular pathways implicated in OSCC and 4 genes altered in the extracellular matrix (ECM) receptor pathway were validated by quantitative real-time polymerase chain reaction (qRT-PCR).

CONCLUSION

Using 4 expression array datasets, we have developed a robust method for analyzing pathways altered in OSCC.

Cancer and neurodegenerative disorders: pathogenic convergence through microRNA regulation

Although cancer and neurodegenerative disease are two distinct pathological disorders, emerging evidence indicates that these two types of disease share common mechanisms of genetic and molecular abnormalities. Recent studies show that individual microRNAs (miRNAs) could be involved in the pathology of both diseases, indicating that the mechanisms of these two seemingly dichotomous diseases converge in the dysregulation of gene expression at the post-transcriptional level. Given the increasing evidence showing that miRNA-based therapeutic strategies that modulate the activity of one or more miRNAs are potentially effective for a wide range of pathological conditions, the involvement of miRNAs in the common pathways of leading both diseases suggests a bright future for developing common therapeutic approaches for both diseases. Moreover, the miRNAs that are dysregulated in both diseases may hold promise as uniquely informative diagnostic markers. Here, we review recent studies on the miRNAs that have been implicated in both cancer and neurodegenerative diseases.

Global profiling and molecular characterization of alternative splicing events misregulated in lung cancer

Alternative splicing (AS) is a widespread mechanism underlying the generation of proteomic and regulatory complexity. However, which of the myriad of human AS events play important roles in disease is largely unknown. To identify frequently occurring AS events in lung cancer, we used AS microarray profiling and reverse transcription-PCR (RT-PCR) assays to survey patient-matched normal and adenocarcinoma tumor tissues from the lungs of 29 individuals diagnosed with non-small cell lung cancer (NSCLC). Of 5,183 profiled alternative exons, four displayed tumor-associated changes in the majority of the patients. These events affected transcripts from the VEGFA, MACF1, APP, and NUMB genes. Similar AS changes were detected in NUMB and APP transcripts in primary breast and colon tumors. Tumor-associated increases in NUMB exon 9 inclusion correlated with reduced levels of NUMB protein expression and activation of the Notch signaling pathway, an event that has been linked to tumorigenesis. Moreover, short hairpin RNA (shRNA) knockdown of NUMB followed by isoform-specific rescue revealed that expression of the exon 9-skipped (nontumor) isoform represses Notch target gene activation whereas expression of the exon 9-included (tumor) isoform lacks this activity and is capable of promoting cell proliferation. The results thus reveal widespread AS changes in NSCLC that impact cell signaling in a manner that likely contributes to tumorigenesis.

Genetic determinants at the interface of cancer and neurodegenerative disease

It has been hypothesized that oncogenesis and neurodegeneration may share common mechanistic foundations. Recent evidence now reveals a number of genes in which alteration leads to either carcinogenesis or neurodegeneration, depending on cellular context. Pathways that have emerged as having critical roles in both cancer and neurodegenerative disease include those involving genes such as PARK2, ATM, PTEN, PTPRD, and mTOR. A number of mechanisms have been implicated, and commonly affected cellular processes include cell cycle regulation, DNA repair, and response to oxidative stress. For example, we have recently shown that the E3 ubiquitin ligase PARK2 is mutated or deleted in many different human malignancies and helps drive loss on chromosome 6q25.2-27, a genomic region frequently deleted in cancers. Mutation in PARK2 is also the most common cause of juvenile Parkinson's disease. Mutations in PARK2 result in an upregulation of its substrate cyclin E, resulting in dysregulated entry into the cell cycle. In neurons, this process results in cell death, but in cycling cells, the result is a growth advantage. Thus, depending on whether the cell affected is a dividing cell or a post-mitotic neuron, responses to these alterations may differ, ultimately leading to varying disease phenotypes. Here, we review the substantial data implicating specific genes in both cancer and neurodegenerative disease.

Histone deacetylase inhibitor valproic acid inhibits cancer cell proliferation via down-regulation of the alzheimer amyloid precursor protein

The beta-amyloid precursor protein (APP) represents a type I transmembrane glycoprotein that is ubiquitously expressed. In the brain, it is a key player in the molecular pathogenesis of Alzheimer disease. Its physiological function is however less well understood. Previous studies showed that APP is up-regulated in prostate, colon, pancreatic tumor, and oral squamous cell carcinoma. In this study, we show that APP has an essential role in growth control of pancreatic and colon cancer. Abundant APP staining was found in human pancreatic adenocarcinoma and colon cancer tissue. Interestingly, treating pancreatic and colon cancer cells with valproic acid (VPA, 2-propylpentanoic acid), a known histone deacetylase (HDAC) inhibitor, leads to up-regulation of GRP78, an endoplasmic reticulum chaperone immunoglobulin-binding protein. GRP78 is involved in APP maturation and inhibition of tumor cell growth by down-regulation of APP and secreted soluble APPalpha. Trichostatin A, a pan-HDAC inhibitor, also lowered APP and increased GRP78 levels. In contrast, treating cells with valpromide, a VPA derivative lacking HDAC inhibitory properties, had no effect on APP levels. VPA did not modify the level of epidermal growth factor receptor, another type I transmembrane protein, and APLP2, a member of the APP family, demonstrating the specificity of the VPA effect on APP. Small interfering RNA-mediated knockdown of APP also resulted in significantly decreased cell growth. Based on these observations, the data suggest that APP down-regulation via HDAC inhibition provides a novel mechanism for pancreatic and colon cancer therapy.

Induction of terminal differentiation in melanoma cells on downregulation of beta-amyloid precursor protein

The incidence of melanoma, the most aggressive type of skin cancer, is increasing dramatically, and an effective treatment for patients with advanced disease is as yet unavailable. Greater insight into the molecular features of primary and metastatic melanoma is required, particularly the identification of key regulatory genes that shield the tumor cells from terminal differentiation and apoptosis. The beta-amyloid precursor protein (APP) is a cell surface receptor and the transmembrane precursor of the Abeta-peptide, which has an important role in Alzheimer's disease. The study presented here provides evidence that APP is expressed at high levels in advanced-stage melanomas, and that the cells cleave APP and secrete sAPP. We show that blocking the expression of APP by RNA interference impairs the proliferation of metastatic melanoma cells and leads to their terminal and irreversible differentiation. In addition, suppressing APP expression in a metastatic melanoma cell line renders the cells susceptible to several chemotherapeutic agents. Targeting APP may thus constitute a new approach to the treatment of this disease.

Amyloid precursor protein is a primary androgen target gene that promotes prostate cancer growth

Androgen receptor (AR) is a critical transcription factor that regulates various target genes and contributes to the pathophysiology of prostate cancer hormone dependently. Here, we identify amyloid precursor protein (APP) as a primary androgen target through chromatin immunoprecipitation (ChIP) combined with genome tiling array analysis (ChIP-chip). ChIP-treated DNA were obtained from prostate cancer LNCaP cells with R1881 or vehicle treatment using AR or acetylated histone H3 antibodies. Ligand-dependent AR binding was further enriched by PCR subtraction. Using chromosome 21/22 arrays, we identified APP as one of the androgen-regulated genes with adjacent functional AR binding sites. APP expression is androgen-inducible in LNCaP cells and APP immunoreactivity was correlated with poor prognosis in patients with prostate cancer. Gain-of-function and loss-of-function studies revealed that APP promotes the tumor growth of prostate cancer. The present study reveals a novel APP-mediated pathway responsible for the androgen-dependent growth of prostate cancer. Our findings will indicate that APP could be a potential molecular target for the diagnosis and treatment of prostate cancer.

Reduced amyloidogenic processing of the amyloid beta-protein precursor by the small-molecule Differentiation Inducing Factor-1

The detection of cell cycle proteins in Alzheimer's disease (AD) brains may represent an early event leading to neurodegeneration. To identify cell cycle modifiers with anti-Abeta properties, we assessed the effect of Differentiation-Inducing Factor-1 (DIF-1), a unique, small-molecule from Dictyostelium discoideum, on the proteolysis of the amyloid beta-protein precursor (APP) in a variety of different cell types. We show that DIF-1 slows cell cycle progression through G0/G1 that correlates with a reduction in cyclin D1 protein levels. Western blot analysis of DIF-treated cells and conditioned medium revealed decreases in the levels of secreted APP, mature APP, and C-terminal fragments. Assessment of conditioned media by sandwich ELISA showed reduced levels of Abeta40 and Abeta42, also demonstrating that treatment with DIF-1 effectively decreases the ratio of Abeta42 to Abeta40. In addition, DIF-1 significantly diminished APP phosphorylation at residue T668. Interestingly, site-directed mutagenesis of APP residue Thr668 to alanine or glutamic acid abolished the effect of DIF-1 on APP proteolysis and restored secreted levels of Abeta. Finally, DIF-1 prevented the accumulation of APP C-terminal fragments induced by the proteasome inhibitor lactacystin, and calpain inhibitor N-acetyl-leucyl-leucyl-norleucinal (ALLN). Our findings suggest that DIF-1 affects G0/G1-associated amyloidogenic processing of APP by a gamma-secretase-, proteasome- and calpain-insensitive pathway, and that this effect requires the presence of residue Thr668.

Localizations of endogenous APP/APP-proteolytic products are consistent with microtubular transport

Dementia of the Alzheimer type (DAT) is associated with the accumulation of beta-amyloid (A beta) peptides derived from beta-amyloid precursor protein (APP). Goldstein and coworkers have suggested that APP acts as a cargo receptor connecting post-Golgi vesicles and motor proteins. Sisodia and colleagues have suggested that APP is a passive passenger within the vesicles. Both views predict that one should be able to visualize colocalizations of APP with microtubules, the object of the present investigation. To avoid possible artifacts created by APP overexpression, we studied endogenous expression in a human neuroblastoma cell line (SK-N-SH). Using high resolution fluorescence microscopy and antibodies specific for the amino termini of APP and A beta sequences, we found that endogenous APP and A beta peptide immunoreactivities colocalized with microtubules in interphase cells. Disruption of microtubules, followed by fixation at various time points during repolymerization, allowed us to observe the sequence and timing of these colocalizations in interphase cells. In addition, to our surprise, we found that A beta immunoreactivities colocalize with the mitotic spindle, a bundle of specialized microtubules. Because of the condensed cytoplasm found in neurons, we suggest that SK-N-SH cells might be a more convenient experimental system for exploring the mechanisms that underlie these protein localizations and the pathology that might result from altered APP protein structure and function.

AP-2 participates in the transcriptional control of the amyloid precursor protein (APP) gene in oral squamous cell carcinoma

Amyloid precursor protein (APP) has been implicated in squamous cell carcinoma. In this study we show that forced expression of the transcription factor activating protein 2alpha (AP-2alpha) results in significantly increased steady state levels of APP mRNA in human keratinocytes. Sequence analysis of the 5' end of the human APP gene revealed five putative binding sites for AP-2, suggesting that APP is a direct target for transactivation by AP-2. AP-2 protein bound at least 3 of these putative promoter elements in vitro as determined by electrophoretic mobility shift assay. Chromatin immunoprecipitation (ChIP) analysis showed that these binding sites were occupied by AP-2 in cells, thus indicating the relevance to AP-2 binding in vivo. We then analyzed APP and AP-2 mRNA and protein expression in squamous cell carcinoma tumor samples. Analysis of RNA extracted from human tissue showed a significant positive correlation between AP-2alpha and APP mRNA expression. Immunohistochemical staining of tumor samples also demonstrated a positive correlation which was substantiated through western blot studies. Taken together, these findings demonstrate a role for the transcription factor AP-2alpha in the regulation of APP gene expression in human keratinocytes.

Amyloid-beta precursor-like protein APLP1 is a novel p53 transcriptional target gene that augments neuroblastoma cell death upon genotoxic stress

The tumor suppressor p53 is a key modulator of the cellular stress response, inducing cell-cycle arrest, apoptosis, senescence and cell differentiation. To evaluate further the molecular mechanism underlying p53 function, the transcriptional profiles of proliferating and senescent WI-38 cells, both wild-type p53 expressers and counterparts with an inactivated p53, were compared by DNA microarray analysis. In particular, the amyloid-beta precursor-like protein 1 (APLP1) is induced in senescent cells in a p53-dependent manner. APLP1 was confirmed to be a novel transcriptional target of p53 by in vivo and in vitro characterization of a p53 responsive element found in the first intron of the APLP1 gene locus. APLP1 knockdown experiments demonstrate that APLP1 is required for the proliferation of fibroblastic and epithelial cells. Moreover, depletion of APLP1 expression diminishes stress-induced apoptosis of neural cells, whereas ectopic APLP1 expression augments apoptosis. Based on these data, a mechanism is proposed whereby p53-dependent induction of APLP1 is involved in neural cell death, and which may exacerbate neuronal cell loss in some acute or chronic neurodegenerative disorders.

Suppression of beta-amyloid precursor protein signaling into the nucleus by estrogens mediated through complex formation between the estrogen receptor and Fe65

The C-terminal fragment of the beta-amyloid precursor protein produced after cleavage by gamma-secretase, namely, APPct or AICD, has been shown to form a multimeric complex with the adaptor protein Fe65 and to regulate transcription through the recruitment of the histone acetyltransferase Tip60. The present study shows that 17beta-estradiol inhibits the transcriptional and apoptotic activities of the APPct complex by a process involving the interaction of estrogen receptor alpha (ERalpha) with Fe65. ERalpha-Fe65 complexes were detected both in vitro and in the mouse brain, and recruitment of ERalpha to the promoter of an APPct target gene (KAI1) was demonstrated. Our studies reveal a novel mechanism of estrogen action, which may explain the well-known neuroprotective functions of estrogens as well as the complex role of this female hormone in the pathogenesis of neuronal degeneration diseases.