Cellular prion protein accelerates colorectal cancer metastasis via the Fyn-SP1-SATB1 axis

The expression of pro-prion, a transmembrane isoform of the prion protein, leads to the constitutive activation of the canonical Wnt/β-catenin pathway to sustain the stem-like phenotype of human glioblastoma cells

BACKGROUND

Cellular prion protein (PrPC) is a widely expressed membrane-anchored glycoprotein, which has been associated with the development and progression of several types of human malignancies, controlling cancer stem cell activity. However, the different molecular mechanisms regulated by PrPC in normal and tumor cells have not been characterized yet.

METHODS

To assess the role of PrPC in patient-derived glioblastoma stem cell (GSC)-enriched cultures, we generated cell lines in which PrPC was either overexpressed or down-regulated and investigated, in 2D and 3D cultures, its role in cell proliferation, migration, and invasion. We evaluated the role of PrPC in supporting GSC stemness and the intracellular signaling involved using qRT-PCR, immunocytofluorescence, and Western blot.

RESULTS

Stable PrPC down-regulation leads to a significant reduction of GSC proliferation, migration, and invasiveness. These effects were associated with the inhibition of the expression of stemness genes and overexpression of differentiation markers. At molecular level PrPC down-regulation caused a significant inhibition of Wnt/β-catenin pathway, through a reduced expression of Wnt and Frizzled ligand/receptor subtypes, resulting in the inhibition of β-catenin transcriptional activity,  as demonstrated by the reduced expression of its target genes. The specificity of PrPC in these effects was demonstrated by rescuing the phenotype and the biological activity of PrPC down-regulated GSCs by re-expressing the protein. To get insights into the distinct mechanisms by which PrPC regulates proliferation in GSCs, but not in normal astrocytes, we analyzed structural features of PrPC in glioma stem cells and astrocytes using Western blot and immunofluorescence techniques. Using Pi-PLC, an enzyme that cleaves GPI anchors, we show that, in GSCs, PrP is retained within the plasma membrane in an immature Pro-PrP isoform whereas in astrocytes, it is expressed in its mature PrPC form, anchored on the extracellular face of the plasma membrane.

CONCLUSIONS

The persistence of Pro-PrP in GSCs is an altered cellular mechanism responsible of the aberrant, constitutive activation of Wnt/β-catenin pathway, which contributes to glioblastoma malignant features. Thus, the activity of Pro-PrP may represent a targetable vulnerability in glioblastoma cells, offering a novel approach for differentiating and eradicating glioblastoma stem cells.

Roles of prion proteins in mammalian development

Prion protein (PrP) is highly conserved and is expressed in most tissues in a developmental stage-specific manner. Glycosylated cellular prion protein (PrPC) is found in most cells and subcellular areas as a physiological regulating molecule. On the other hand, the amyloid form of PrPC, scrapie PrP (PrPSC), causes transmissible pathogenesis in the central nervous system and induces degeneration of the nervous system. Although many amyloids are reversible and critical in determining the fate, differentiation, and physiological functions of cells, thus far, PrPSC originating from PrPC is not. Although many studies have focused on disorders involving PrPC and the deletion mammalian models for PrPC have no severe phenotype, it has been suggested that PrPC has a role in normal development. It is conserved and expressed from gametes to adult somatic cells. In addition, severe developmental phenotypes appear in PrP null zebrafish embryos and in various mammalian cell model systems. In addition, it has been well established that PrPC is strongly involved in the stemness and differentiation of embryonic stem cells and progenitors. Thus far, many studies on PrPC have focused mostly on disease-associated conditions with physiological roles as a complex platform but not on development. The known roles of PrPC depend on the interacting molecules through its flexible tail and domains. PrPC interacts with membrane, and various intracellular and extracellular molecules. In addition, PrPC and amyloid can stimulate signaling pathways differentially. In this review, we summarize the function of prion protein and discuss its role in development.

Upregulated PrPC by HBx enhances NF-κB signal via liquid-liquid phase separation to advance liver cancer

Cellular prion protein (PrPC) has been implicated in carcinogenic through the activation of various signal pathways, however, the precise mechanisms remain elusive. In vitro studies have shown that PrPC is prone to undergo liquid-liquid phase separation (LLPS). However, it remains unknown whether PrPC contributes to LLPS-inducing cancer development. Herein, we observed an upregulation of PrPC expression in hepatitis B virus-positive hepatocellular carcinoma (HCC). Subsequent investigation revealed that HBx of HBV enhances PrPC expression in a dose-dependent manner by binding to CREB1. Furthermore, we demonstrated that PrPC undergoes LLPS and recruits TRAF2/6, TAB2/3, and TAK1 protein, thereby activating the NF-κB signaling pathway and promoting tumor progression. Notably, although unable to undergo LLPS itself, the α3 helix of PrPC is essential for its activation of the NF-κB signaling pathway during the LLPS process. Further analysis unveiled that disulfide bond formation within the C-terminal domain of PrPC is necessary for its LLPS and subsequent activation of the NF-κB signaling pathway. Additionally, our findings indicate that NF-κB activation by PrPC condensates leads to increased IL-8 expression which further promotes tumor development.

PRNP is a pan-cancer prognostic and immunity-related to EMT in colorectal cancer

Background

Prion protein gene (PRNP) is widely expressed in a variety of tissues. Although the roles of PRNP in several cancers have been investigated, no pan-cancer analysis has revealed its relationship with tumorigenesis and immunity.

Methods

Comprehensive analyses were conducted on The Cancer Genome Atlas (TCGA) Pan-Cancer dataset from the University of California Santa Cruz (UCSC) database to determine the expression of PRNP and its potential prognostic implications. Immune infiltration and enrichment analysis methods were used to ascertain correlations between PRNP expression levels, tumor immunity, and immunotherapy. Additionally, gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) methods were employed to examine possible signaling pathways involving PRNP. In vitro experiments using CCK-8 assay, Wound healing assay, and Transwell assay to detect the effect of Cellular prion protein (PrPC) on proliferation, migration, and invasion in colorectal cancer (CRC) cells. The expression levels of epithelial-mesenchymal transition (EMT)-related proteins (N-cadherin, E-cadherin, Vimentin and Snail) were detected by western blot.

Results

Among most cancer types, PRNP is expressed at high levels, which is linked to the prognosis of patients. PRNP expression is strongly associated with immune infiltrating cells, immunosuppressive cell infiltration and immune checkpoint molecules. In addition to tumor mutation burden (TMB), substantial correlations are detected between PRNP expression and microsatellite instability (MSI) in several cancers. In vitro cell studies inferred that PrPC enhanced the proliferation, migration, invasion, and EMT of CRC cells.

Conclusion

PRNP serves as an immune-related prognostic marker that holds promise for predicting outcomes related to CRC immunotherapy while simultaneously promoting cell proliferation, migration, and invasion activities. Furthermore, it potentially plays a role in governing EMT regulation within CRC.

Glucose metabolism-based signature predicts prognosis and immunotherapy strategies for colon adenocarcinoma

BACKGROUND

The global prevalence and metastasis rates of colon adenocarcinoma (COAD) are high, and therapeutic success is limited. Although previous research has primarily explored changes in gene phenotypes, the incidence rate of COAD remains unchanged. Metabolic reprogramming is a crucial aspect of cancer research and therapy. The present study aims to develop cluster and polygenic risk prediction models for COAD based on glucose metabolism pathways to assess the survival status of patients and potentially identify novel immunotherapy strategies and related therapeutic targets.

METHODS

COAD-specific data (including clinicopathological information and gene expression profiles) were sourced from The Cancer Genome Atlas (TCGA) and two Gene Expression Omnibus (GEO) datasets (GSE33113 and GSE39582). Gene sets related to glucose metabolism were obtained from the MSigDB database. The Gene Set Variation Analysis (GSVA) method was utilized to calculate pathway scores for glucose metabolism. The hclust function in R, part of the Pheatmap package, was used to establish a clustering system. The mutation characteristics of identified clusters were assessed via MOVICS software, and differentially expressed genes (DEGs) were filtered using limma software. Signature analysis was performed using the least absolute shrinkage and selection operator (LASSO) method. Survival curves, survival receiver operating characteristic (ROC) curves and multivariate Cox regression were analyzed to assess the efficacy and accuracy of the signature for prognostic prediction. The pRRophetic program was employed to predict drug sensitivity, with data sourced from the Genomics of Drug Sensitivity in Cancer (GDSC) database.

RESULTS

Four COAD subgroups (i.e., C1, C2, C3 and C4) were identified based on glucose metabolism, with the C4 group having higher survival rates. These four clusters were bifurcated into a new Clust2 system (C1 + C2 + C3 and C4). In total, 2175 DEGs were obtained (C1 + C2 + C3 vs. C4), from which 139 prognosis-related genes were identified. ROC curves predicting 1-, 3- and 5-year survival based on a signature containing nine genes showed an area under the curve greater than 0.7. Meanwhile, the study also found this feature to be an important predictor of prognosis in COAD and accordingly assessed the risk score, with higher risk scores being associated with a worse prognosis. The high-risk and low-risk groups responded differently to immunotherapy and chemotherapeutic agents, and there were differences in functional enrichment pathways.

CONCLUSIONS

This unique signature based on glucose metabolism may potentially provide a basis for predicting patient prognosis, biological characteristics and more effective immunotherapy strategies for COAD.

Cellular Prion protein moonlights vascular smooth muscle cell fate: Surveilled by trophoblast cells

Uterine spiral artery remodeling (uSAR) is a hallmark of hemochorial placentation. Compromised uSAR leads to adverse pregnancy outcomes. Salient developmental events involved in uSAR are active areas of research and include (a) trophendothelial cell invasion into the spiral arteries, selected demise of endothelial cells; (b) de-differentiation of vascular smooth muscle cells (VSMC); and (c) migration and/or death of VSMCs surrounding spiral arteries. Here we demonstrated that cellular prion (PRNP) is expressed in the rat metrial gland, the entry point of spiral arteries with the highest expression on E16.5, the day at which trophoblast invasion peaks. PRNP is expressed in VSMCs that drift away from the arterial wall. RNA interference of Prnp functionally restricted migration and invasion of rat VSMCs. Furthermore, PRNP interacted with two migration-promoting factors, focal adhesion kinase (FAK) and platelet-derived growth factor receptor-β (PDGFR-β), forming a ter-molecular complex in both the metrial gland and A7r5 cells. The presence of multiple putative binding site of odd skipped related-1 (OSR1) transcription factor on the Prnp promoter was observed using in silico promoter analysis. Ectopic overexpression of OSR1 increased, and knockdown of OSR1 decreased expression of PRNP in VSMCs. Coculture of VSMCs with rat primary trophoblast cells decreased the levels of OSR1 and PRNP. Interestingly, PRNP knockdown led to apoptotic death in ~9% of VSMCs and activated extrinsic apoptotic pathways. PRNP interacts with TRAIL-receptor DR4 and protects VSMCs from TRAIL-mediated apoptosis. These results highlight the biological functions of PRNP in VSMC cell-fate determination during uteroplacental development, an important determinant of healthy pregnancy outcome.

The role of cellular prion protein in immune system

Numerous studies have investigated the cellular prion protein (PrPC) since its discovery. These investigations have explained that its structure is predominantly composed of alpha helices and short beta sheet segments, and when its abnormal scrapie isoform (PrPSc) is infected, PrPSc transforms the PrPC, leading to prion diseases, including Creutzfeldt-Jakob disease in humans and bovine spongiform encephalopathy in cattle. Given its ubiquitous distribution across a variety of cellular types, the PrPC manifests a diverse range of biological functions, including cell-cell adhesion, neuroprotection, signalings, and oxidative stress response. PrPC is also expressed in immune tissues, and its functions in these tissues include the activation of immune cells and the formation of secondary lymphoid tissues, such as the spleen and lymph nodes. Moreover, high expression of PrPC in immune cells plays a crucial role in the pathogenesis of prion diseases. In addition, it affects inflammation and the development and progression of cancer via various mechanisms. In this review, we discuss the studies on the role of PrPC from various immunological perspectives. [BMB Reports 2023; 56(12): 645-650].

The role of cellular prion protein in immune system

Numerous studies have investigated the cellular prion protein (PrPC) since its discovery. These investigations have explained that its structure is predominantly composed of alpha helices and short beta sheet segments, and when its abnormal scrapie isoform (PrPSc) is infected, PrPSc transforms the PrPC, leading to prion diseases, including Creutzfeldt-Jakob disease in humans and bovine spongiform encephalopathy in cattle. Given its ubiquitous distribution across a variety of cellular types, the PrPC manifests a diverse range of biological functions, including cell-cell adhesion, neuroprotection, signalings, and oxidative stress response. PrPC is also expressed in immune tissues, and its functions in these tissues include the activation of immune cells and the formation of secondary lymphoid tissues, such as the spleen and lymph nodes. Moreover, high expression of PrPC in immune cells plays a crucial role in the pathogenesis of prion diseases. In addition, it affects inflammation and the development and progression of cancer via various mechanisms. In this review, we discuss the studies on the role of PrPC from various immunological perspectives. [BMB Reports 2023; 56(12): 645-650].

The Multifaceted Functions of Prion Protein (PrPC) in Cancer

The cellular prion protein (PrPC) is a glycoprotein anchored to the cell surface by glycosylphosphatidylinositol (GPI). PrPC is expressed both in the brain and in peripheral tissues. Investigations on PrPC's functions revealed its direct involvement in neurodegenerative and prion diseases, as well as in various physiological processes such as anti-oxidative functions, copper homeostasis, trans-membrane signaling, and cell adhesion. Recent findings have revealed the ectopic expression of PrPC in various cancers including gastric, melanoma, breast, colorectal, pancreatic, as well as rare cancers, where PrPC promotes cellular migration and invasion, tumor growth, and metastasis. Through its downstream signaling, PrPC has also been reported to be involved in resistance to chemotherapy and tumor cell apoptosis. This review summarizes the variance of expression of PrPC in different types of cancers and discusses its roles in their development and progression, as well as its use as a potential target to treat such cancers.

Melatonin and 5-fluorouracil combination chemotherapy: opportunities and efficacy in cancer therapy

Combined chemotherapy is a treatment method based on the simultaneous use of two or more therapeutic agents; it is frequently necessary to produce a more effective treatment for cancer patients. Such combined treatments often improve the outcomes over that of the monotherapy approach, as the drugs synergistically target critical cell signaling pathways or work independently at different oncostatic sites. A better prognosis has been reported in patients treated with combination therapy than in patients treated with single drug chemotherapy. In recent decades, 5-fluorouracil (5-FU) has become one of the most widely used chemotherapy agents in cancer treatment. This medication, which is soluble in water, is used as the first line of anti-neoplastic agent in the treatment of several cancer types including breast, head and neck, stomach and colon cancer. Within the last three decades, many studies have investigated melatonin as an anti-cancer agent; this molecule exhibits various functions in controlling the behavior of cancer cells, such as inhibiting cell growth, inducing apoptosis, and inhibiting invasion. The aim of this review is to comprehensively evaluate the role of melatonin as a complementary agent with 5-FU-based chemotherapy for cancers. Additionally, we identify the potential common signaling pathways by which melatonin and 5-FU interact to enhance the efficacy of the combined therapy. Video abstract.

Melatonin-Assisted Cisplatin Suppresses Urinary Bladder Cancer Cell Proliferation and Growth through Inhibiting PrPC-Regulated Cell Stress and Cell Proliferation Signaling

This study investigated whether melatonin (Mel) would promote cisplatin to suppress the proliferation and growth of bladder cancer (BC) cells by inhibiting cellular prion protein (PrP^C)-mediated cell stress and cell proliferation signaling. An immunohistochemical staining of tissue arrays from BC patients demonstrated that the PrP^C expression was significantly upregulated from stage I to III BC (p < 0.0001). The BC cellline of T24 was categorized into G1 (T24), G2 (T24 + Mel/100 μM), G3 (T24+cisplatin/6 μM), G4 (PrP^C overexpression in T24 (i.e., PrP^C-OE-T24)), G5 (PrP^C-OE-T24+Mel), and G6 (PrP^C-OE-T24+cisplatin). When compared with a human uroepithelial cell line (SV-HUC-1), the cellular viability/wound healing ability/migration rate were significantly increased in T24 cells (G1) and further significantly increased in PrP^C-OE-T24 cells (G4); and they were suppressed in Mel (G2/G5) or cisplatin (G3/G6) treatment (all p < 0.0001). Additionally, the protein expressions of cell proliferation (PI3K/p-Akt/p-m-TOR/MMP-9/PrP^C), cell cycle/mitochondrial functional integrity (cyclin-D1/clyclin-E1/ckd2/ckd4/mitochondrial-cytochrome-C/PINK1), and cell stress (RAS/c-RAF/p-MEK1/2, p-ERK1/2) markers showed a similar pattern of cell viability among the groups (all p < 0.001). After the BC cell line of UMUC3 was implanted into nude mouse backs, by day 28 mthe BC weight/volume and the cellular levels of PrP^C/MMP-2/MMP-9 were significantly, gradually reduced from groups one to four (all p < 0.0001). The protein expressions of cell proliferation (PI3K/p-Akt/p-m-TOR/MMP-9/PrP^C), cell cycle/mitophagy (cyclin-D1/clyclin-E1/ckd2/ckd4/PINK1), and cell stress (RAS/c-RAF/p-MEK1,2/p-ERK1,2) signaling were significantly, progressively reduced from groups one to four, whereas the protein expressions of apoptotic (Mit-Bax/cleaved-caspase-3/cleaved-PARP) and oxidative stress/mitochondrial damaged (NOX-1/NOX-2/cytosolic-cytochrome-C/p-DRP1) markers expressed an opposite pattern of cell proliferation signaling among the groups (all p < 0.0001). Mel-cisplatin suppressed BC cell growth/proliferation via inhibiting the PrP^C in upregulating the cell proliferation/cell stress/cell cycle signaling.

Cellular Prion Protein Role in Cancer Biology: Is It A Potential Therapeutic Target?

Cancers are worldwide health concerns, whether they are sporadic or hereditary. The fundamental mechanism that causes somatic or oncogenic mutations and ultimately aids cancer development is still unknown. However, mammalian cells with protein-only somatic inheritance may also contribute to cancerous malignancies. Emerging data from a recent study show that prion-like proteins and prions (PrPC) are crucial entities that have a functional role in developing neurological disorders and cancer. Furthermore, excessive PrPC expression profiling has also been detected in non-neuronal tissues, such as the lymphoid cells, kidney, GIT, lung, muscle, and mammary glands. PrPC expression is strongly linked with the proliferation and metastasis of pancreatic, prostate, colorectal, and breast malignancies. Similarly, experimental investigation presented that the PrPC expression, including the prion protein-coding gene (PRNP) and p53 ag are directly associated with tumorigenicity and metastasis (tumor suppressor gene). The ERK2 (extracellular signal-regulated kinase) pathway also confers a robust metastatic capability for PrPC-induced epithelial to mesenchymal transition. Additionally, prions could alter the epigenetic regulation of genes and overactive the mitogen-activated protein kinase (MAPK) signaling pathway, which promotes the development of cancer in humans. Protein overexpression or suppression caused by a prion and prion-like proteins has also been linked to oncogenesis and metastasis. Meanwhile, additional studies have discovered resistance to therapeutic targets, highlighting the significance of protein expression levels as potential diagnostic indicators and therapeutic targets.

The multiple functions of PrPC in physiological, cancer, and neurodegenerative contexts

Cellular prion protein (PrP^C) is a highly conserved glycoprotein, present both anchored in the cell membrane and soluble in the extracellular medium. It has a diversity of ligands and is variably expressed in numerous tissues and cell subtypes, most notably in the central nervous system (CNS). Its importance has been brought to light over the years both under physiological conditions, such as embryogenesis and immune system homeostasis, and in pathologies, such as cancer and neurodegenerative diseases. During development, PrP^C plays an important role in CNS, participating in axonal growth and guidance and differentiation of glial cells, but also in other organs such as the heart, lung, and digestive system. In diseases, PrP^C has been related to several types of tumors, modulating cancer stem cells, enhancing malignant properties, and inducing drug resistance. Also, in non-neoplastic diseases, such as Alzheimer's and Parkinson's diseases, PrP^C seems to alter the dynamics of neurotoxic aggregate formation and, consequently, the progression of the disease. In this review, we explore in detail the multiple functions of this protein, which proved to be relevant for understanding the dynamics of organism homeostasis, as well as a promising target in the treatment of both neoplastic and degenerative diseases.

Sp1 is overexpressed and associated with progression and poor prognosis in bladder urothelial carcinoma patients

BACKGROUND

Specificity protein 1 (Sp1) is a transcription factor that exerts key functions in the carcinogenesis and progression of various types of cancer. However, its expression and prognostic value in bladder urothelial carcinoma (BUC) have yet to be completely elucidated.

METHODS

The present study performed reverse transcription-quantitative polymerase chain reaction (RT-qPCR) to examine Sp1 mRNA expression in 12 pairs of urothelial carcinoma and adjacent normal bladder tissues. Immunohistochemistry (IHC) was performed in 113 paraffin-embedded urothelial carcinoma tissues to detect the expression of Sp1. Kaplan-Meier plots and Cox proportional hazards regression model were used to analyze the correlation between Sp1 expression and patient prognosis.

RESULTS

The mRNA expression of Sp1 was elevated in the urothelial carcinoma by RT-qPCR compared with their paired normal bladder tissues. Among 113 cases of patients with urothelial carcinoma, there were 39 low histological grade and 74 high histological grade, 61 unifocal tumor and 52 multifocal tumor, 78 cases in Ta, T1, and T2 stages, and 35 cases in T3 and T4 stages. The enhanced expression of Sp1 mRNA was observed in tumors with a high histological grade, and invasive and metastatic samples. Immunohistochemistry revealed that Sp1 high expression was significantly correlated with the histological grade, tumor stage, vascular invasion, lymph node metastasis and distant metastasis (P < 0.05). Kaplan-Meier analysis demonstrated that elevated Sp1 expression in cancer tissue was correlated with a significantly poor overall survival (OS) and disease-free survival (DFS) compared with samples with low Sp1 expression (P < 0.05). Multivariate analyses by Cox's proportional hazard model also revealed that the expression of Sp1 was an independent prognostic factor in urothelial carcinoma.

CONCLUSION

Sp1 expression is significantly elevated in urothelial carcinoma and may be used to identify a subset of patients with aggressive behaviors and poor clinical outcomes. Sp1 is a potential novel independent prognostic biomarker for patients with urothelial carcinoma following surgery.

SEPA: Signalling entropy-based algorithm to evaluate personalized pathway activation for survival analysis on pan-cancer data

MOTIVATION

Biomarkers with prognostic ability and biological interpretability can be used to support decision-making in the survival analysis. Genes usually form functional modules to play synergistic roles, such as pathways. Predicting significant features from the functional level can effectively reduce the adverse effects of heterogeneity and obtain more reproducible and interpretable biomarkers. Personalized pathway activation inference can quantify the dysregulation of essential pathways involved in the initiation and progression of cancers, and can contribute to the development of personalized medical treatments.

RESULTS

In this study, we propose a novel method to evaluate personalized pathway activation based on signalling entropy for survival analysis (SEPA), which is a new attempt to introduce the information-theoretic entropy in generating pathway representation for each patient. SEPA effectively integrates pathway-level information into gene expression data, converting the high-dimensional gene expression data into the low-dimensional biological pathway activation scores. SEPA shows its classification power on the prognostic pan-cancer genomic data, and the potential pathway markers identified based on SEPA have statistical significance in the discrimination of high-risk and low-risk cohorts and are likely to be associated with the initiation and progress of cancers. The results show that SEPA scores can be used as an indicator to precisely distinguish cancer patients with different clinical outcomes, and identify important pathway features with strong discriminative power and biological interpretability.

AVAILABILITY

The MATLAB-package for SEPA is freely available from https://github.com/xingyili/SEPA.

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

Melatonin: Regulation of Prion Protein Phase Separation in Cancer Multidrug Resistance

The unique ability to adapt and thrive in inhospitable, stressful tumor microenvironments (TME) also renders cancer cells resistant to traditional chemotherapeutic treatments and/or novel pharmaceuticals. Cancer cells exhibit extensive metabolic alterations involving hypoxia, accelerated glycolysis, oxidative stress, and increased extracellular ATP that may activate ancient, conserved prion adaptive response strategies that exacerbate multidrug resistance (MDR) by exploiting cellular stress to increase cancer metastatic potential and stemness, balance proliferation and differentiation, and amplify resistance to apoptosis. The regulation of prions in MDR is further complicated by important, putative physiological functions of ligand-binding and signal transduction. Melatonin is capable of both enhancing physiological functions and inhibiting oncogenic properties of prion proteins. Through regulation of phase separation of the prion N-terminal domain which targets and interacts with lipid rafts, melatonin may prevent conformational changes that can result in aggregation and/or conversion to pathological, infectious isoforms. As a cancer therapy adjuvant, melatonin could modulate TME oxidative stress levels and hypoxia, reverse pH gradient changes, reduce lipid peroxidation, and protect lipid raft compositions to suppress prion-mediated, non-Mendelian, heritable, but often reversible epigenetic adaptations that facilitate cancer heterogeneity, stemness, metastasis, and drug resistance. This review examines some of the mechanisms that may balance physiological and pathological effects of prions and prion-like proteins achieved through the synergistic use of melatonin to ameliorate MDR, which remains a challenge in cancer treatment.

Cellular Prion Protein Is Essential for Myocardial Regeneration but Not the Recovery of Left Ventricular Function from Apical Ballooning

This study tested the hypothesis that cellular prion protein (PrP^C) played an essential role in myocardial regeneration and recovery of left ventricular ejection fraction (LVEF) from apical takotsubo cardiomyopathy (TCM) induced by transaortic constriction (TAC). In vitro study was categorized into G1 (H9C2), G2 (H9C2-overexpression-PrP^C), G3 (H9C2-overexpression-PrP^C + Stelazine/1 uM), and G4 (H9C2 + siRNA-PrP^C), respectively. The results showed that the protein expressions of PrP^C, cell-stress signaling (p-PI3K/p-Akt/p-m-TOR) and signal transduction pathway for cell proliferation/division (RAS/c-RAF/p-MEK/p-ERK1/2) were lowest in G1, highest in G2, significantly higher in G3 than in G4 (all p < 0.001). Adult-male B6 mice (n = 30) were equally categorized in group 1 (sham-control), group 2 (TAC) for 14 days, then relieved the knot and administered BrdU (50 ug/kg/intravenously/q.6.h for two times from day-14 after TAC) and group 3 (TAC + Stelazine/20 mg/kg/day since day 7 after TAC up to day 21 + BrdU administered as group 2), and animals were euthanized at day 28. The results showed that by day 28, the LVEF was significantly higher in group 1 than in groups 2/3 and significantly higher in group 3 than in group 2, whereas the LV chamber size exhibited an opposite pattern of LVEF (all p < 0.0001). The protein expressions of PrP^C/p-PI3K/p-Akt/p-m-TOR/cyclin D/cyclin E and cellular-proliferation biomarkers (Ki67/PCNA/BrdU) exhibited an opposite pattern of LVEF (all p < 0.0001) among the three groups, whereas the protein expressions of RAS/c-RAF/p-MEK/p-ERK1/2 were significantly and progressively increased from groups 1 to 3 (all p < 0.0001). In conclusion, PrP^C participated in regulating the intrinsic response of cell-stress signaling and myocardial regeneration but did not offer significant benefit on recovery of the heart function in the setting of TCM.

The Cellular Prion Protein and the Hallmarks of Cancer

Simple Summary

The cellular prion protein PrP^C is best known for its involvement, under its pathogenic isoform, in a group of neurodegenerative diseases. Notwithstanding, an emerging role for PrP^C in various cancer-associated processes has attracted increasing attention over recent years. PrP^C is overexpressed in diverse types of solid cancers and has been incriminated in various aspects of cancer biology, most notably proliferation, migration, invasion and metastasis, as well as resistance to cytotoxic agents. This article aims to provide a comprehensive overview of the current knowledge of PrP^C with respect to the hallmarks of cancer, a reference framework encompassing the major characteristics of cancer cells.

Abstract

Beyond its causal involvement in a group of neurodegenerative diseases known as Transmissible Spongiform Encephalopathies, the cellular prion protein PrP^C is now taking centre stage as an important contributor to cancer progression in various types of solid tumours. The prion cancer research field has progressively expanded in the last few years and has yielded consistent evidence for an involvement of PrP^C in cancer cell proliferation, migration and invasion, therapeutic resistance and cancer stem cell properties. Most recent data have uncovered new facets of the biology of PrP^C in cancer, ranging from its control on enzymes involved in immune tolerance to its radio-protective activity, by way of promoting angiogenesis. In the present review, we aim to summarise the body of literature dedicated to the study of PrP^C in relation to cancer from the perspective of the hallmarks of cancer, the reference framework defined by Hanahan and Weinberg.

The Role of Cellular Prion Protein in Cancer Biology: A Potential Therapeutic Target

Prion protein has two isoforms including cellular prion protein (PrP^C) and scrapie prion protein (PrP^Sc). PrP^Sc is the pathological aggregated form of prion protein and it plays an important role in neurodegenerative diseases. PrP^C is a glycosylphosphatidylinositol (GPI)-anchored protein that can attach to a membrane. Its expression begins at embryogenesis and reaches the highest level in adulthood. PrP^C is expressed in the neurons of the nervous system as well as other peripheral organs. Studies in recent years have disclosed the involvement of PrP^C in various aspects of cancer biology. In this review, we provide an overview of the current understanding of the roles of PrP^C in proliferation, cell survival, invasion/metastasis, and stem cells of cancer cells, as well as its role as a potential therapeutic target.

Prion Protein of Extracellular Vesicle Regulates the Progression of Colorectal Cancer

Simple Summary

Cellular prion protein (PrP^C) are overexpressed in cancers and related to cancer proliferation, invasion, metastasis, and drug resistance. The aim of our study was to investigate the role of PrP^C-expressing exosomes regulating the colorectal cancer cells (CRC) behavior and tumor progression. We confirmed the increased sphere formation, expression of cancer initiating genes, motility, and tumor growth by hypoxic exosomes. Also, PrP^C-expressing exosomes induced the microenvironment of metastasis via increase of endothelial permeability and angiogenic cytokine secretion. The treatment of anti-PrP^C and 5-fluorouracil decreased the tumor progression. Targeting PrP^C is an effective therapeutic strategy in cancer therapy.

Abstract

Colorectal cancer (CRC) is one of the leading causes of cancer-related death due to its aggressive metastasis in later stages. Although there is a growing interest in the tumorigenic role of cellular prion protein (PrP^C) in the process of metastasis, the precise mechanism behind the cellular communication involving prion proteins remains poorly understood. This study found that hypoxic tumor microenvironment increased the PrP^C-expressing exosomes from CRC, and these exosomes regulate the CRC cell behavior and tumor progression depending on the expression of PrP^C. Hypoxic exosomes from CRC cells promoted sphere formation, the expression of tumor-inducing genes, migration, invasion, and tumor growth. Furthermore, these exosomes increased endothelial permeability, migration, invasion, and angiogenic cytokine secretion. These effects were associated with PrP^C expression. Application of anti-PrP^C antibody with 5-fluorouracil significantly suppressed the CRC progression in a murine xenograft model. Taken together, these findings indicate that PrP-expressing exosomes secreted by hypoxic CRC cells are a key factor in the tumorigenic CRC-to-CRC and CRC-to-endothelial cell communication. Significance: These findings suggest that inhibiting PrP^C in hypoxic exosomes during chemotherapy may be an effective therapeutic strategy in colorectal cancer.

The Role of Cellular Prion Protein in Promoting Stemness and Differentiation in Cancer

Simple Summary

Aside from its well-established role in prion disorders, in the last decades the significance of cellular prion protein (PrP^C) expression in human cancers has attracted great attention. An extensive body of work provided evidence that PrP^C contributes to tumorigenesis by regulating tumor growth, differentiation, and resistance to conventional therapies. In particular, PrP^C over-expression has been related to the acquisition of a malignant phenotype of cancer stem cells (CSCs) in a variety of solid tumors, encompassing pancreatic ductal adenocarcinoma, osteosarcoma, breast, gastric, and colorectal cancers, and primary brain tumors as well. According to consensus, increased levels of PrP^C endow CSCs with self-renewal, proliferative, migratory, and invasive capacities, along with increased resistance to anti-cancer agents. In addition, increasing evidence demonstrates that PrPc also participates in multi-protein complexes to modulate the oncogenic properties of CSCs, thus sustaining tumorigenesis. Therefore, strategies aimed at targeting PrP^C and/or PrP^C-organized complexes could be a promising approach for anti-cancer therapy.

Abstract

Cellular prion protein (PrP^C) is seminal to modulate a variety of baseline cell functions to grant homeostasis. The classic role of such a protein was defined as a chaperone-like molecule being able to rescue cell survival. Nonetheless, PrP^C also represents the precursor of the deleterious misfolded variant known as scrapie prion protein (PrP^Sc). This variant is detrimental in a variety of prion disorders. This multi-faceted role of PrP is greatly increased by recent findings showing how PrP^C in its folded conformation may foster tumor progression by acting at multiple levels. The present review focuses on such a cancer-promoting effect. The manuscript analyzes recent findings on the occurrence of PrP^C in various cancers and discusses the multiple effects, which sustain cancer progression. Within this frame, the effects of PrP^C on stemness and differentiation are discussed. A special emphasis is provided on the spreading of PrP^C and the epigenetic effects, which are induced in neighboring cells to activate cancer-related genes. These detrimental effects are further discussed in relation to the aberrancy of its physiological and beneficial role on cell homeostasis. A specific paragraph is dedicated to the role of PrP^C beyond its effects in the biology of cancer to represent a potential biomarker in the follow up of patients following surgical resection.

The Cellular Prion Protein: A Promising Therapeutic Target for Cancer

Studies on the cellular prion protein (PrP^C) have been actively conducted because misfolded PrP^C is known to cause transmissible spongiform encephalopathies or prion disease. PrP^C is a glycophosphatidylinositol-anchored cell surface glycoprotein that has been reported to affect several cellular functions such as stress protection, cellular differentiation, mitochondrial homeostasis, circadian rhythm, myelin homeostasis, and immune modulation. Recently, it has also been reported that PrP^C mediates tumor progression by enhancing the proliferation, metastasis, and drug resistance of cancer cells. In addition, PrP^C regulates cancer stem cell properties by interacting with cancer stem cell marker proteins. In this review, we summarize how PrP^C promotes tumor progression in terms of proliferation, metastasis, drug resistance, and cancer stem cell properties. In addition, we discuss strategies to treat tumors by modulating the function and expression of PrP^C via the regulation of HSPA1L/HIF-1α expression and using an anti-prion antibody.

Prion Protein at the Leading Edge: Its Role in Cell Motility

Cell motility is a central process involved in fundamental biological phenomena during embryonic development, wound healing, immune surveillance, and cancer spreading. Cell movement is complex and dynamic and requires the coordinated activity of cytoskeletal, membrane, adhesion and extracellular proteins. Cellular prion protein (PrPC) has been implicated in distinct aspects of cell motility, including axonal growth, transendothelial migration, epithelial-mesenchymal transition, formation of lamellipodia, and tumor migration and invasion. The preferential location of PrPC on cell membrane favors its function as a pivotal molecule in cell motile phenotype, being able to serve as a scaffold protein for extracellular matrix proteins, cell surface receptors, and cytoskeletal multiprotein complexes to modulate their activities in cellular movement. Evidence points to PrPC mediating interactions of multiple key elements of cell motility at the intra- and extracellular levels, such as integrins and matrix proteins, also regulating cell adhesion molecule stability and cell adhesion cytoskeleton dynamics. Understanding the molecular mechanisms that govern cell motility is critical for tissue homeostasis, since uncontrolled cell movement results in pathological conditions such as developmental diseases and tumor dissemination. In this review, we discuss the relevant contribution of PrPC in several aspects of cell motility, unveiling new insights into both PrPC function and mechanism in a multifaceted manner either in physiological or pathological contexts.

Identification of Prion Disease-Related Somatic Mutations in the Prion Protein Gene (PRNP) in Cancer Patients

Prion diseases are caused by misfolded prion protein (PrP^Sc) and are accompanied by spongiform vacuolation of brain lesions. Approximately three centuries have passed since prion diseases were first discovered around the world; however, the exact role of certain factors affecting the causative agent of prion diseases is still debatable. In recent studies, somatic mutations were assumed to be cause of several diseases. Thus, we postulated that genetically unstable cancer tissue may cause somatic mutations in the prion protein gene (PRNP), which could trigger the onset of prion diseases. To identify somatic mutations in the PRNP gene in cancer tissues, we analyzed somatic mutations in the PRNP gene in cancer patients using the Cancer Genome Atlas (TCGA) database. In addition, to evaluate whether the somatic mutations in the PRNP gene in cancer patients had a damaging effect, we performed in silico analysis using PolyPhen-2, PANTHER, PROVEAN, and AMYCO. We identified a total of 48 somatic mutations in the PRNP gene, including 8 somatic mutations that are known pathogenic mutations of prion diseases. We identified significantly different distributions among the types of cancer, the mutation counts, and the ages of diagnosis between the total cancer patient population and cancer patients carrying somatic mutations in the PRNP gene. Strikingly, although invasive breast carcinoma and glioblastoma accounted for a high percentage of the total cancer patient population (9.9% and 5.4%, respectively), somatic mutations in the PRNP gene have not been identified in these two cancer types. We suggested the possibility that somatic mutations of the PRNP gene in glioblastoma can be masked by a diagnosis of prion disease. In addition, we found four aggregation-prone somatic mutations, these being L125F, E146Q, R151C, and K204N. To the best of our knowledge, this is the first specific analysis of the somatic mutations in the PRNP gene in cancer patients.

The Role of SATB1 in Tumour Progression and Metastasis

Carcinogenesis is a long-drawn, multistep process, in which metastatic spread is an unequivocal hallmark of a poor prognosis. The progression and dissemination of epithelial cancers is commonly thought to rely on the epidermal-mesenchymal transition (EMT) process. During EMT, epithelial cells lose their junctions and apical-basal polarity, and they acquire a mesenchymal phenotype with its migratory and invasive capabilities. One of the proteins involved in cancer progression and EMT may be SATB1 (Special AT-Rich Binding Protein 1)-a chromatin organiser and a global transcriptional regulator. SATB1 organizes chromatin into spatial loops, providing a "docking site" necessary for the binding of further transcription factors and chromatin modifying enzymes. SATB1 has the ability to regulate whole sets of genes, even those located on distant chromosomes. SATB1 was found to be overexpressed in numerous malignancies, including lymphomas, breast, colorectal, prostate, liver, bladder and ovarian cancers. In the solid tumours, an elevated SATB1 level was observed to be associated with an aggressive phenotype, presence of lymph node, distant metastases, and a poor prognosis. In this review, we briefly describe the prognostic significance of SATB1 expression in most common human cancers, and analyse its impact on EMT and metastasis.

Cellular prion protein regulates the differentiation and function of adipocytes through autophagy flux

The role of autophagy modulation in adipogenic differentiation and the possible autophagy modulators targeting adipogenesis remain unclear. In this study, we investigated whether normal cellular prion protein (PrP<C>) is involved in the modulation of autophagy and affects adipogenic differentiation in vivo and in vitro. Surprisingly, autophagy flux signals were activated in the adipose tissue of prion protein-deficient mice and PrP<C>-deleted 3T3-L1 adipocytes. The activation of autophagy flux mediated by PrP<C> deletion was confirmed in the adipose tissue via transmission electron microscopy. Adipocyte differentiation factors were highly induced in prion protein-deficient adipose tissue and 3T3-L1 adipocytes. In addition, deletion of prion protein significantly increased visceral fat volume, body fat weight, adipocyte cell size, and body weight gain in Prnp-knockout mice and increased lipid accumulation in PrP<C> siRNA-transfected 3T3-L1 cells. However, the overexpression of prion protein using adenovirus inhibited the autophagic flux signals, lipid accumulation, and the PPAR-γ and C/EBP-α mRNA and protein expression levels in comparison to those in the control cells. Our results demonstrated that deletion of normal prion protein accelerated adipogenic differentiation and lipid accumulation mediated via autophagy flux activation.

Baicalin induces apoptosis in SW480 cells through downregulation of the SP1 transcription factor

Colorectal cancer occurs throughout the world but is most common in developed countries. Cancer progression is believed to be driven by genetic mutations in this complex condition. Risk factors for developing colorectal cancer include a genetic family history, long-term ulcerative colitis, and colonic polyps. The use of baicalin has been reported to be clinically efficacious against colon tumors in Asian countries despite an unclear mechanism of action. Several cancers have been found to be biologically dependent on the specificity protein 1 (sp1) transcription factor family. We hypothesized that baicalin may exert its chemotherapeutic effects by sp1 downregulation. Using the SW480 human colorectal cancer cell line, we investigated the physiological properties of baicalin. Our experiments were designed toward clarifying three goals: (a) to determine the mRNA expression profile of transcription factors in colorectal cancer patients using a microarray-based analysis; (b) to determine the effects of baicalin on the sp1 transcription factor with western blotting and reporter cell assays; and (c) to contrast the effects of mithramycin-A (an sp1 transcription factor inhibitor) and baicalin using western blotting and reporter cell assays. Both baicalin and mithramycin-A downregulated sp1 expression, attenuated SW480 cell proliferation, and increased cell apoptosis. Baicalin inhibited sp1 expression and led to SW480 apoptosis, thus clarifying the effect of this traditional Chinese medicine compound in the treatment of colon cancer.

Melatonin and 5-fluorouracil co-suppress colon cancer stem cells by regulating cellular prion protein-Oct4 axis

Melatonin suppresses tumor development. However, the exact relationship between melatonin and cancer stem cells (CSCs) is poorly understood. This study found that melatonin inhibits colon CSCs by regulating the PrP^C -Oct4 axis. In specimens from patients with colorectal cancer, the expressions of cellular prion protein (PrP^C ) and Oct4 were significantly correlated with metastasis and tumor stages. Co-treatment with 5-fluorouracil (5-FU) and melatonin inhibited the stem cell markers Oct4, Nanog, Sox2, and ALDH1A1 by downregulating PrP^C . In this way, tumor growth, proliferation, and tumor-mediated angiogenesis were suppressed. In colorectal CSCs, PRNP overexpression protects Oct4 against inhibition by 5-FU and melatonin. In contrast, Nanog, Sox2, and ALDH1A1 have no such protection. These results indicate that PrP^C directly regulates Oct4, whereas it indirectly regulates Nanog, Sox2, and ALDH1A1. Taken together, our findings suggest that co-treatment with anticancer drug and melatonin is a potential therapy for colorectal cancer. Furthermore, PrP^C maintains cancer stemness during tumor progression. Therefore, targeting the PrP^C -Oct4 axis may prove instrumental in colorectal cancer therapy.

Organization of GPI-anchored proteins at the cell surface and its physiopathological relevance

Glycosylphosphatidylinositol (GPI)-anchored proteins (GPI-APs) are a class of proteins attached to the extracellular leaflet of the plasma membrane via a post-translational modification, the glycolipid anchor. The presence of both glycolipid anchor and protein portion confers them unique features. GPI-APs are expressed in all eukaryotes, from fungi to plants and animals. They display very diverse functions ranging from enzymatic activity, signaling, cell adhesion, cell wall metabolism, neuritogenesis, and immune response. Likewise other plasma membrane proteins, the spatio-temporal organization of GPI-APs is critical for their biological activities in physiological conditions. In this review, we will summarize the latest findings on plasma membrane organization of GPI-APs and the mechanism of its regulation in different cell types. We will also examine the involvement of specific GPI-APs namely the prion protein PrP^C, the Folate Receptor alpha and the urokinase plasminogen activator receptor in human diseases focusing on neurodegenerative diseases and cancer.

Prognostic and Clinicopathological Significance of SATB1 in Colorectal Cancer: A Meta-Analysis

Background: A large number of studies have reported the aberrant expression of special AT-rich sequence binding protein 1 (SATB1) in colorectal cancer (CRC). However, the role of SATB1 in CRC is still controversial. Therefore, we performed this meta-analysis to elucidate the prognostic and clinical value of SATB1 in CRC patients.

Methods: We searched Web of Science, EMBASE and PubMed entirely in January 2018 to identify related articles. Pooled Hazard ratio (HR) was adopted to evaluate the prognostic value of SATB1 in CRC and odd ratio (OR) was used to assess the clinicopathological significance of SATB1 in CRC.

Results: Ten eligible studies containing 7 on prognosis and 9 on clinicopathological characteristics were finally included in the present meta-analysis. Results revealed that patients with high expression of SATB1 tended to have shorter overall survival (OS) (pooled HR: 1.64, 95% CI: 1.04–2.57). Besides, we also discovered that the expression of SATB1 was associated with histologic grade (OR = 1.88, 95% CI: 1.06–3.34), distant metastasis (OR = 1.43, 95% CI: 1.11–1.85) and lymph node metastasis (OR = 1.50, 95% CI: 1.03–2.19).

Conclusion: Broadly speaking, our meta-analysis demonstrated that high expression level of SATB1 was related to poor prognosis in CRC patients.

Cellular Prion Protein Enhances Drug Resistance of Colorectal Cancer Cells via Regulation of a Survival Signal Pathway

Anti-cancer drug resistance is a major problem in colorectal cancer (CRC) research. Although several studies have revealed the mechanism of cancer drug resistance, molecular targets for chemotherapeutic combinations remain elusive. To address this issue, we focused on the expression of cellular prion protein (PrP^C) in 5-FU-resistant CRC cells. In 5-FU-resistant CRC cells, PrP^C expression is significantly increased, compared with that in normal CRC cells. In the presence of 5-FU, PrP^C increased CRC cell survival and proliferation by maintaining the activation of the PI3K-Akt signaling pathway and the expression of cell cycle-associated proteins, including cyclin E, CDK2, cyclin D1, and CDK4. In addition, PrP^C inhibited the activation of the stress-associated proteins p38, JNK, and p53. Moreover, after treatment of 5-FU-resistant CRC cells with 5-FU, silencing of PrP^C triggered apoptosis via the activation of caspase-3. These results indicate that PrP^C plays a key role in CRC drug resistance. The novel strategy of combining chemotherapy with PrP^C targeting may yield efficacious treatments of colorectal cancer.

Prognostic significance of SATB1 in gastrointestinal cancer: a meta-analysis and literature review

Background

The special AT-rich sequence-binding proteins 1 (SATB1) is a major regulator involved in cell differentiation. It has been shown that SATB1 acts as an oncogenic regulator. The clinical and prognostic significance of SATB1 in gastrointestinal cancer remains controversial. The purpose of this study is to conduct a systematic review and meta-analysis to elucidate the impact of SATB1 in gastrointestinal cancer.

Results

A total of 3174 gastrointestinal cancer patients from 15 studies were included. The correlation between SATB1 expression and OS or RFS was investigated in 12 and 5 studies respectively. The results of meta-analysis showed that SATB1 overexpression is inversely correlated with OS (combined HR: 1.79, p = 0.0003) and RFS (combined HR: 2.46, p < 0.0001). In subgroup analysis, SATB1 expression is significantly correlated with poor prognosis in gastrointestinal cancer in Asian population. SATB1 expression is associated with stage, invasion depth, lymph node metastasis and distant metastasis.

Methodology

Published studies with data on overall survival (OS) and/or relapse free survival (RFS) and SATB1 expression were searched from Cochrane Library, PubMed and Embase (up to Dec 30, 2016). The outcome measurement is hazard ratio (HR) for OS or RFS related with SATB1 expression. Two reviewers independently screened the literatures, extracted the data and performed meta-analysis using RevMan 5.3.0 software. The combined HRs were calculated by fixed- or random-effect models.

Conclusions

The results of this meta-analysis suggest that SATB1 overexpression is related to advanced stage, lymph node metastasis and distant metastasis. SATB1 overexpression is a marker indicating poor prognosis in gastrointestinal cancer.

SNF5 deficiency induces apoptosis resistance by repressing SATB1 expression in Sézary syndrome

SNF5, is a core member of the SWI/SNF chromatin remodeling complex. It's deficiency leads to multiple types of aggressive cancer. Sézary syndrome, a leukemic variant of cutaneous T-cell lymphoma, is characterized by its resistance to apoptosis. Although the cause of apoptosis resistance is still poorly understood, recent evidence has revealed the importance of SATB1 in the apoptosis resistance of Sézary syndrome. In this study, we show that SNF5 is an upstream regulator of SATB1 in several conditions and that both are deficient in Sézary cells. Additionally, SNF5 not only controls the expression of SATB1, but also utilizes SATB1 to recruit itself to specific sites. Overexpression of SNF5 induces SATB1 expression and partially reverse apoptosis resistance phenotype in Sézary cells. These results suggest that both SNF5 and SATB1 may regulate apoptosis-related genes in Sézary syndrome. Thus, targeting SWI/SNF complex may represent a promising approach for Sézary syndrome therapy.

Fyn knockdown inhibits migration and invasion in cholangiocarcinoma through the activated AMPK/mTOR signaling pathway

Cholangiocarcinoma (CCA) is a rare and fatal tumor. In previous decades, there has been a steady increase in the incidence and mortality rates of this tumor worldwide. Metastasis is regarded as the major factor that contributes to poor prognosis in CCA patients. Studies therefore aim to develop novel therapeutic targets to control CCA metastasis. Fyn is known to enhance expression and promote metastasis in various cancers, including pancreatic cancer, prostate cancer and colorectal cancer. However, the exact function and mechanism of Fyn in CCA metastasis remains unclear. In the present study, mRNA and protein expression levels of Fyn, AMP-activated protein kinase (AMPK), phosphorylated (p-)AMPK, mammalian target of rapamycin (mTOR) and p-mTOR were measured, using the reverse transcription-quantitative polymerase chain reaction and western blot analysis, in CCA tissues and cell lines. In addition, Transwell assays were used to determine the migratory and invasive abilities of human CCA QBC939, following transfection. In the present study, it was found that Fyn was overexpressed in CCA cell lines. Fyn knockdown inhibited CCA cell migration and invasion. Furthermore, it was demonstrated that Fyn knockdown induces phosphorylation of AMPK, inhibits downstream phosphorylation of mTOR, and activate the AMPK/mTOR signaling pathway. Compound C, an AMPK inhibitor, inhibited the AMPK/mTOR signaling pathway, and reversed the effect of Fyn knockdown on migration and invasion of CCA cells. In conclusion, the present study suggests that Fyn knockdown inhibits cell migration and invasion by regulating the AMPK/mTOR signaling pathway in CCA cell lines and that Fyn knockdown is a potential target for anti-CCA therapy.

Role of HSPA1L as a cellular prion protein stabilizer in tumor progression via HIF-1α/GP78 axis

The cellular prion protein (PrP^C) is associated with metastasis, tumor progression and recurrence; however, the precise mechanisms underlying its action is not well understood. Our study found that PrP^C degradation decreased tumor progression in colorectal cancer (CRC). In a CRC cell line and human CRC tissue exposed to hypoxia, induced heat-shock 70-kDa protein-1-like (HSPA1L) expression stabilized hypoxia-inducible factor-1α (HIF-1α) protein and promoted PrP^C accumulation and tumorigenicity in vivo. PrP^C was degraded via the proteasome pathway mediated by the ubiquitin-protein E3 ligase glycoprotein 78 (GP78), which interacts directly with PrP^C. However, hypoxia-induced HSPA1L interacted with GP78 and inhibited its functions. HSPA1L knockdown facilitated the interaction of GP78 and PrP^C, thereby increasing PrP^C ubiquitination. Thus, GP78 was identified as the ubiquitinase for PrP^C, thereby revealing an essential mechanism that controls PrP^C levels in CRC. Our results suggest that the HSPA1L/HIF-1α/GP78 axis has a crucial role in PrP^C accumulation during tumor progression.

Specificity protein 1: Its role in colorectal cancer progression and metastasis

Specificity protein 1 (Sp1) is a widely expressed transcription factor that plays an important role in the promotion of oncogenes required for tumor survival, progression and metastasis. Sp1 is highly expressed in several cancers including colorectal cancer (CRC) and is related to poor prognosis. Therefore, targeting Sp1 is a rational for CRC therapy. In this review, we will recapitulate the current understanding of Sp1 signaling, its molecular mechanisms, and its potential involvement in CRC growth, progression and metastasis. We will also discuss the current therapeutic drugs for CRC and their mechanism of action via Sp1.

Identifying and Analyzing Novel Epilepsy-Related Genes Using Random Walk with Restart Algorithm

As a pathological condition, epilepsy is caused by abnormal neuronal discharge in brain which will temporarily disrupt the cerebral functions. Epilepsy is a chronic disease which occurs in all ages and would seriously affect patients' personal lives. Thus, it is highly required to develop effective medicines or instruments to treat the disease. Identifying epilepsy-related genes is essential in order to understand and treat the disease because the corresponding proteins encoded by the epilepsy-related genes are candidates of the potential drug targets. In this study, a pioneering computational workflow was proposed to predict novel epilepsy-related genes using the random walk with restart (RWR) algorithm. As reported in the literature RWR algorithm often produces a number of false positive genes, and in this study a permutation test and functional association tests were implemented to filter the genes identified by RWR algorithm, which greatly reduce the number of suspected genes and result in only thirty-three novel epilepsy genes. Finally, these novel genes were analyzed based upon some recently published literatures. Our findings implicate that all novel genes were closely related to epilepsy. It is believed that the proposed workflow can also be applied to identify genes related to other diseases and deepen our understanding of the mechanisms of these diseases.

Prion protein binding to HOP modulates the migration and invasion of colorectal cancer cells

Colorectal cancer (CRC) is one of the most frequently diagnosed malignancies. The generation of conventional treatments has improved, but approximately 50 % of patients with CRC who undergo potentially curative surgery ultimately relapse and die, usually as a consequence of metastatic disease. Our previous findings showed that engagement of the cellular prion protein (PrP(C)) to its ligand HSP70/90 heat shock organizing protein (HOP) induces proliferation of glioblastomas. In addition, PrP(C) has been described as an important modulator of colorectal tumor growth. Here, we investigated the biological relevance of the PrP(C)-HOP interaction in CRC cells. We demonstrate that HOP induced the migration and invasion of CRC cell lines in a PrP(C)-dependent manner and that phosphorylation of the ERK1/2 pathway is a downstream mediator of these effects. Additionally, we show that a HOP peptide with the ability to bind PrP(C) and abolish the PrP(C)-HOP interaction inhibited the migration and invasion of CRC cells. Together, these data indicate that the disruption of the PrP(C)-HOP complex could be a potential therapeutic target for modulating the migratory and invasive cellular properties that lead to metastatic CRC.

Targeting prion protein interactions in cancer

In recent years, prion protein (PrP(C)) has been considered as a promising target molecule for cancer therapies, due its direct or indirect participation in tumor growth, metastasis, and resistance to cell death induced by chemotherapy. PrP(C) functions as a scaffold protein, forming multiprotein complexes on the plasma membrane, which elicits distinct signaling pathways involved in diverse biological phenomena and could be modulated depending on the cell type, complex composition, and organization. In addition, PrP(C) and its partners participate in self-renewal of embryonic, tissue-specific stem cells and cancer stem cells, which are suggested to be responsible for the origin, maintenance, relapse, and dissemination of tumors. Interference with protein-protein interaction has been recognized as an important therapeutic strategy in cancer; indeed, the possible interference in PrP(C) engagement with specific partners is a novel strategy. Recently, our group successfully used that approach to interfere with the interaction between PrP(C) and HSP-90/70 organizing protein (HOP, also known as stress-inducible protein 1 - STI1) to control the growth of human glioblastoma in animal models. Thus, PrP(C)-organized multicomplexes have emerged as feasible candidates for anti-tumor therapy, warranting further exploration.

Cellular prion protein regulates invasion and migration of breast cancer cells through MMP-9 activity

Function of cellular prion protein (PrP(c)) in cancer progression has not been elucidated yet. Ectopic expression of PrP(c) increases the invasion and migration of breast cancer cell line, MCF-7 cells. Overexpressed PrP(c) increases matrix metalloprotease-9 (MMP-9) expression by enhancing association of NF-κB in promoter of MMP-9 gene and ERK signaling in MCF-7 cells. Whereas, silencing of PrP(c) by siRNA suppresses ERK activation and MMP-9 expression resulting the down-regulation of MD-MB231 cell migration and invasion. Overall, these results suggest that PrP(c) contribute the breast cancer invasion and migration via MMP-9.

Prion protein scrapie and the normal cellular prion protein

Prions are infectious proteins and over the past few decades, some prions have become renowned for their causative role in several neurodegenerative diseases in animals and humans. Since their discovery, the mechanisms and mode of transmission and molecular structure of prions have begun to be established. There is, however, still much to be elucidated about prion diseases, including the development of potential therapeutic strategies for treatment. The significance of prion disease is discussed here, including the categories of human and animal prion diseases, disease transmission, disease progression and the development of symptoms and potential future strategies for treatment. Furthermore, the structure and function of the normal cellular prion protein (PrP(C)) and its importance in not only in prion disease development, but also in diseases such as cancer and Alzheimer's disease will also be discussed.

Cellular prion protein contributes to LS 174T colon cancer cell carcinogenesis by increasing invasiveness and resistance against doxorubicin-induced apoptosis

As the cellular prion protein (PrP(C)) has been implicated in carcinogenesis, we aimed to investigate the effects of cancer cell-specific PrP(C) overexpression from the invasion, metastasis, and apoptosis aspects, by performing cell motility assays, cell proliferation assays under anchorage-dependent and anchorage-independent conditions, and apoptosis evasion when subjected to multiple anti-cancer drugs. Overexpression of PrP(C) in LS 174T was achieved by stable transfection. PrP(C) overexpression was shown to increase cell proliferation in anchorage-dependent and anchorage-independent manners, as shown by more viable cells in 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, more colonies formed in soft agar assay and increased resistance to anoikis in poly-2-hydroxyethyl methacrylate-coated surface. PrP(C) overexpression also increased cell motility and invasiveness of LS 174T. Cell adhesion to extracellular matrix using collagen- and fibronectin-coated surfaces revealed increased cell attachment in LS 174T cells overexpressing PrP(C). Analysis of apoptotic and necrotic cells by propidium iodide/annexin V-fluorescein isothiocyanate microscopy and 7-amino-actinomycin D/annexin V-phycoerythrin flow cytometry revealed that PrP(C) overexpression attenuated doxorubicin-induced apoptosis. Human apoptosis antibody array with 35 apoptosis-related proteins revealed that three inhibitor of apoptosis proteins (IAPs)-survivin, X-linked inhibitor of apoptosis protein (XIAP), and cellular inhibitor of apoptosis protein-1 (cIAP-1)-were upregulated in LS 174T cells overexpressing PrP(C) in doxorubicin-induced apoptosis. In conclusion, the overexpression of PrP(C) could enhance the invasiveness and survival of LS 174T colorectal cancer cells, indicating that PrP(C) plays a role in colorectal cancer biology.

SATB1 and 2 in colorectal cancer

The special AT-rich sequence-binding proteins 1 and 2 (SATB1/2) are nuclear matrix associated proteins that are transcription factors involved in chromatin remodeling and gene regulation. Expression of the SATB2 gene is tissue-specific, and the only epithelial cells expressing SATB2 are the glandular cells of the lower gastrointestinal tract where its expression is regulated by microRNA-31 (miR-31) and miR-182. SATB2, along with its homolog SATB1, are thought to be involved in various cancers with their roles in this disease being specific to the type of cancer. Colorectal cancer (CRC) provides the largest association of SATB2 with cancer and the roles of SATB2 are better defined and more studied in CRC than in any other cancer type. SATB1 displays a negative association with SATB2 in CRC. The various studies that have investigated the involvement of SATB1 and 2 in CRC have produced consistent findings. Here, we form four major conclusions regarding the role of these proteins in CRC and their potential clinical value: (i) SATB2 is a sensitive marker to distinguish CRC from other cancer types, (ii) Reduced expression of SATB2 in CRC is associated with poor prognosis, (iii) High levels of SATB1 expression facilitate CRC and are associated with poor prognosis and (iv) Overexpression of miR-31 and -182 in CRC leads to more aggressive cancer. This review will describe several of the key investigations that established these conclusions and highlight results that offer opportunities for future research in the treatment and diagnosis of CRC.

Expression of special AT-rich sequence-binding protein 1 is an independent prognostic factor in cutaneous T-cell lymphoma

Cutaneous T-cell lymphoma (CTCL) is a group of slowly progressive, lymphoproliferative disorders characterized by localization of neoplastic T lymphocytes to the skin. The most common type of CTCL is mycosis fungoides which has a mild clinical course with slow and long progression. The rate of progression is generally slow and takes many years but often remains unpredictable. Special AT-rich sequence-binding protein-1 (SATB1) is a global chromatin organizer which controls gene expression by folding and remodeling chromatin, but which also regulates the level of histone methylation and acetylation, important in differentiation and apoptosis. The aim of the present study was to determine if SATB1 may be considered a prognostic and predictive factor of CTCL. The results showed that moderate and high expression of SATB1 correlate with significantly better prognosis of CTCL patients. Moreover, we showed that downregulation of SATB1 in Jurkat cells caused their resistance to activation-induced cell death. In conclusion, SATB1 expression appears to be a strong candidate as a prognostic factor confirming the inner heterogeneous features of CTCLs.

Expression analysis of genes and pathways associated with liver metastases of the uveal melanoma

Background

Uveal melanoma is an aggressive cancer which has a high percentage metastasizing to the liver, with a worse prognosis. Identification of patients at high risk of metastases may provide information for early detection of metastases and treatment.

Methods

Expression profiling of ocular tumor tissues from 46 liver metastatic uveal melanoma samples and 45 non-metastatic uveal melanoma samples were got from GEO database. Bioinformatic analyses such as the Gene Oncology and Kyoto Encyclopedia of Genes and Genomes were used to identify genes and pathways specifically associated with liver metastases of the uveal melanoma.

Results

A total of 1138 probes were differentially expressed in two group samples. All differential gene interactions in the Signal-Net were analyzed. Of them, 768 probes were up-regulated and 370 down-regulated. They mainly participated in 125 GO terms and 16 pathways. Of the genes differentially expressed between two group cancers, HTR2B, CHL1, the ZNF family, YWHAZ and FYN were the most significantly altered.

Conclusions

Bioinformatics may help excavate and analyze large amounts of data in microarrays by means of rigorous experimental planning, scientific statistical analysis and collection of complete data about liver metastases of uveal melanoma patients. In the present study, a novel differential gene expression pattern was constructed and advanced study will provide new targets for diagnosis and mechanism of uveal melanoma liver metastases.