Cooperation of decay-accelerating factor and membrane cofactor protein in regulating survival of human cervical cancer cells

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.

Identification of an autophagy-related gene signature for survival prediction in patients with cervical cancer

Cervical cancer is one of the most common female malignancy that occurs worldwide and is reported to cause over 300,000 deaths in 2018. Autophagy controls the survival and death of cancerous cells by regulating the degradation process of cytoplasm and cellular organelle. In the present study, the differentially expressed autophagy-related genes (ARGs) between healthy and cancerous cervical tissues (squamous cell neoplasms) were obtained using data from GTEx and The Cancer Genome Atlas (TCGA) database. The functionalities of the differentially expressed ARGs were analyzed using Gene Ontology (GO) as well as the Kyoto Encyclopedia of Genes and Genomes (KEGG) database. Next, we conducted univariate Cox regression assay and obtained 12 ARGs that were associated with the prognosis of cervical cancer patients. We carried out a multivariate Cox regression analysis and developed six ARG-related prognostic signature for the survival prediction of patients with squamous cell cervical cancer (Risk score = − 0.63*ATG3–0.42*BCL2 + 0.85*CD46–0.38*IFNG+ 0.23*NAMPT+ 0.82*TM9SF1). Following the calculation of risk score using the signature, the patients were divided into high and low-risk groups according to the median value. Kaplan-Meier curve demonstrated that patients with a high-risk score tend to have a poor prognosis (P < 0.001). The value for area under the curves corresponding to the receiver operating characteristic (ROC) was 0.740. As observed, the expression of IFNG was negatively associated with lymph node metastasis (P = 0.026), while a high-risk score was significantly associated with increased age (P = 0.008). To further validate the prognostic signature, we carried out a permutation test and confirmed the performance of the risk score. In conclusion, our study developed six ARG-related prognostic signature for patients with squamous cell cervical cancer, which might help in improving the prognostic predictions of such patients.

Comparative transcriptome analysis of peripheral blood mononuclear cells in renal transplant recipients in everolimus- and tacrolimus-based immunosuppressive therapy

To better define the biological impact of immunosuppression on peripheral blood mononuclear cells (PBMC), we employed RNASeq analysis to compare the whole transcriptomic profile of a group of renal transplant recipients undergoing maintenance treatment with Everolimus (EVE) with those treated with Tacrolimus (TAC). Then, obtained results were validated by classical biomolecular methodologies. The statistical analysis allowed the identification of four genes discriminating the 2 study groups: Sushi Domain Containing 4 (SUSD4, P = 0.02), T Cell Leukemia/Lymphoma 1A (TCL1A, P = 0.02), adhesion G protein-coupled receptor E3 (ADGRE3, P = 0.01), Immunoglobulin Heavy Constant Gamma 3 (IGHG3, P = 0.03). All of them were significantly down-regulated in patients treated with EVE compared to TAC. The Area under Receiver Operating Characteristic (AUROC) of the final model based on these 4 genes was 73.1% demonstrating its good discriminative power. RT-PCR and ELISA validated transcriptomic results. Additionally, an in vitro model confirmed that EVE significantly down-regulates (P<0.001) TCL1A, SUSD4, ADGRE3 and IgHG3 in PBMCs as well as in T cells and monocytes isolated from healthy subjects. Taken together, our data, revealed, for the first time, a new four gene-based transcriptomic fingerprint down-regulated by EVE in PBMCs of renal transplant patients that could improve the available knowledge regarding some of the biological/cellular effects of the mTOR-Is (including their antineoplastic and immune-regulatory properties).

Identification of a microRNA signature associated with survivability in cervical squamous cell carcinoma

Background

The aim of this study is to find the potential miRNA expression signature capable of predicting survival time for cervical squamous cell carcinoma (CSCC) patients.

Methods

The expression of 332 miRNAs was measured in 131 (Training cohort) and 130 (Validation cohort) patients with CSCC in the Cancer Genome Atlas (TCGA) data portal. The miRNA expression signature was identified by Cox Proportion Hazard regression model to the Training data set, and subsequently validated in an independent Validation set. Kaplan-Meier curves and the receiver operating characteristic analyses of 5 years were used to access the overall survival of miRNA signature. MiRNA signature-gene target analysis was performed, followed by the construction of the regulatory network. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analysis were used to explore the function of target genes of miRNA signature.

Results

A 2-miRNA expression signature of hsa-mir-642a and hsa-mir-378c associated with survivability was identified in CSCC. Both of them had a significant diagnostic and prognostic value of patients with CSCC. A total of 345 miRNA signature-target pairs were obtained in the miRNA signature-gene target regulatory network, in which 316 genes were targets of has-mir-378c and has-mir-642a. Functional analysis of target genes showed that MAPK signaling pathway, VEGF signaling pathway and endocytosis were the significantly enriched signal pathways that covered most genes.

Conclusions

The 2-miRNA signature adds to the prognostic value of CSCC. In-depth interrogation of the 2-miRNAs will provide important biological insights that finding and developing novel molecularly prediction to improve prognosis for CSCC patients.

Beyond the Role of CD55 as a Complement Component

The complement is a part of the immune system that plays several roles in removing pathogens. Despite the importance of the complement system, the exact role of each component has been overlooked because the complement system was thought to be a nonspecific humoral immune mechanism that worked against pathogens. Decay-accelerating factor (DAF or CD55) is a known inhibitor of the complement system and has recently attracted substantial attention due to its role in various diseases, such as cancer, protein-losing enteropathy, and malaria. Some protein-losing enteropathy cases are caused by CD55 deficiency, which leads to complement hyperactivation, malabsorption, and angiopathic thrombosis. In addition, CD55 has been reported to be an essential host receptor for infection by the malaria parasite. Moreover, CD55 is a ligand of the seven-span transmembrane receptor CD97. Since CD55 is present in various cells, the functional role of CD55 has been expanded by showing that CD55 is associated with a variety of diseases, including cancer, malaria, protein-losing enteropathy, paroxysmal nocturnal hemoglobinuria, and autoimmune diseases. This review summarizes the current understanding of CD55 and the role of CD55 in these diseases. It also provides insight into the development of novel drugs for the diagnosis and treatment of diseases associated with CD55.

Human papillomavirus E6 protein enriches the CD55(+) population in cervical cancer cells, promoting radioresistance and cancer aggressiveness

Accumulating evidence indicates that the human papillomavirus (HPV) E6 protein plays a crucial role in the development of cervical cancer. Subpopulations of cells that reside within tumours are responsible for tumour resistance to cancer therapy and recurrence. However, the identity of such cells residing in cervical cancer and their relationship with the HPV-E6 protein have not been identified. Here, we isolated sphere-forming cells, which showed self-renewal ability, from primary cervical tumours. Gene expression profiling revealed that cluster of differentiation (CD) 55 was upregulated in primary cervical cancer sphere cells. Flow-cytometric analysis detected abundant CD55(+) populations among a panel of HPV-positive cervical cancer cell lines, whereas few CD55(+) cells were found in HPV-negative cervical cancer and normal cervical epithelial cell lines. The CD55(+) subpopulation isolated from the C33A cell line showed significant sphere-forming ability and enhanced tumourigenicity, cell migration, and radioresistance. In contrast, the suppression of CD55 in HPV-positive CaSki cells inhibited tumourigenicity both in vitro and in vivo, and sensitized cells to radiation treatment. In addition, ectopic expression of the HPV-E6 protein in HPV-negative cervical cancer cells dramatically enriched the CD55(+) subpopulation. CRISPR/Cas9 knockout of CD55 in an HPV-E6-overexpressing stable clone abolished the tumourigenic effects of the HPV-E6 protein. Taken together, our data suggest that HPV-E6 protein expression enriches the CD55(+) population, which contributes to tumourigenicity and radioresistance in cervical cancer cells. Targeting CD55 via CRISPR/Cas9 may represent a novel avenue for developing new strategies and effective therapies for the treatment of cervical cancer. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

The dual role of complement in cancer and its implication in anti-tumor therapy

Chronic inflammation has been linked to the initiation of carcinogenesis, as well as the advancement of established tumors. The polarization of the tumor inflammatory microenvironment can contribute to either the control, or the progression of the disease. The emerging participation of members of the complement cascade in several hallmarks of cancer, renders it a potential target for anti-tumor treatment. Moreover, the presence of complement regulatory proteins (CRPs) in most types of tumor cells is known to impede anti-tumor therapies. This review focuses on our current knowledge of complement's potential involvement in shaping the inflammatory tumor microenvironment and its role on the regulation of angiogenesis and hypoxia. Furthermore, we discuss approaches using complement-based therapies as an adjuvant in tumor immunotherapy.

The role of complement in tumor growth

Complement is a central part of the immune system that has developed as a first defense against non-self cells. Neoplastic transformation is accompanied by an increased capacity of the malignant cells to activate complement. In fact, clinical data demonstrate complement activation in cancer patients. On the basis of the use of protective mechanisms by malignant cells, complement activation has traditionally been considered part of the body's immunosurveillance against cancer. Inhibitory mechanisms of complement activation allow cancer cells to escape from complement-mediated elimination and hamper the clinical efficacy of monoclonal antibody-based cancer immunotherapies. To overcome this limitation, many strategies have been developed with the goal of improving complement-mediated effector mechanisms. However, significant work in recent years has identified new and surprising roles for complement activation within the tumor microenvironment. Recent reports suggest that complement elements can promote tumor growth in the context of chronic inflammation. This chapter reviews the data describing the role of complement activation in cancer immunity, which offers insights that may aid the development of more effective therapeutic approaches to control cancer.

The globular heads of the C1q receptor regulate apoptosis in human cervical squamous carcinoma cells via a p53-dependent pathway

Background

The globular heads of the human C1q receptor (gC1qR) localize predominantly to the mitochondrial matrix. gC1qR mediates many biological responses, including growth perturbation, morphological abnormalities and the initiation of apoptosis. The purpose of this study was to investigate the relationship between mitochondrial dysfunction, p53 status and gC1qR expression and the regulation of apoptosis in human cervical squamous carcinoma cells (C33a and SiHa).

Methods

Here, gC1qR expression was examined in human cervical tissues using real-time PCR and Western blot analysis. Apoptotic death of C33a and SiHa cells was assessed by flow cytometric analysis that detected the subG1 population. Mitochondrial function was assessed via ROS generation, the content of cytosolic Ca²⁺, and the change in mitochondrial membrane potential (Δψm). The viability and migration of C33a and SiHa cells were detected via the water-soluble tetrazolium salt (WST-1) assay and the transwell assay, respectively.

Results

gC1qR expression was decreased in cervical squamous cell carcinoma tissues compared with normal tissues. C33a and SiHa cells transfected with a vector encoding gC1qR displayed mitochondrial dysfunction and apoptosis, which was abrogated by the addition of a mutant form of p53 or p53 small interference RNA (siRNA). Furthermore, upon overexpression of gC1qR, cell viability and migration were significantly enhanced, and the apoptosis of C33a and SiHa cells were decreased when cells were treated with mutant p53 or p53 siRNA.

Conclusions

These data support a mechanism whereby gC1qR induces apoptosis through the mitochondrial and p53-dependent pathways in cervical squamous cell carcinoma.

The role of the globular heads of C1q receptor (gC1qR) gene in regulating apoptosis of human cervical squamous cell carcinoma

BACKGROUND

The globular heads of the human C1q receptor (gC1qR) are multi-compartmental and multi-functional cellular proteins. The list of biological responses mediated by the gC1qR includes growth perturbation and morphological abnormalities, along with the initiation of apoptosis. However, the effects of the gC1qR on the apoptosis of cervical squamous carcinoma cells (C33a and SiHa) have not been demonstrated.

METHODS

Here, human cervical tissues were examined for the expression of the gC1qR using real-time PCR and Western blot analysis. Apoptotic death of C33a and SiHa cells was assessed by flow cytometric analysis to detect the subG1 population. Viability, migration and proliferation of C33a and SiHa cells were detected via the water-soluble tetrazolium salt (WST-1) assay, the Transwell assay and the (3)H-thymidine incorporation into DNA assay ((3)H-TdR), respectively.

RESULTS

These data showed that expression of the gC1qR protein was significantly decreased in human cervical squamous cell carcinoma tissues relative to normal cervix tissues. C33a and SiHa cells transfected with a GFP-gC1qR vector resulted in the up-regulation of cellular apoptosis and an apparent increase in the expression of the p38 mitogen-activated protein kinase (p38 MAPK). Further, the changes in C33a and SiHa cells viability, migration and proliferation observed upon overexpression of gC1qR could be abrogated using the p38 MAPK inhibitor SB202190.

CONCLUSION

These data indicate that gC1qR inhibits viability, migration and proliferation of cervical squamous cells carcinoma via the p38 MAPK signalling pathway.

Adenovirus-mediated delivery of CD46 attenuates the alternative complement pathway on RPE: implications for age-related macular degeneration

Activation of the alternative pathway of the complement system has been implicated in the pathogenesis of age-related macular degeneration. Membrane attack complex (MAC) has been identified mainly on the Bruch's membrane and drusen underlying the retinal pigment epithelium (RPE). Membrane cofactor protein (CD46) preferentially regulates the alternative pathway of complement. The aim of this study was to evaluate the potential of increasing CD46 expression on RPE cells using an adenovirus as a gene therapy approach to reduce alternative pathway-mediated damage to RPE cells. We generated a recombinant adenovirus vector expressing human CD46 (hCD46) and delivered the vector to murine hepatocytes and RPE cells in vitro. After incubation in human serum in conditions in which the classical pathway of complement was blocked, we measured alternative pathway-mediated damage of these cells by quantifying lysis and MAC formation. Adenovirus expressing hCD46 was delivered to the subretinal space of adult mice, and 1 week later, ocular flat mounts were challenged with human serum and the levels of complement-mediated damage was quantified. Adenovirus-mediated delivery of hCD46 localizes to the basal and lateral surfaces of RPE cells where it offers protection from alternative pathway-mediated damage, but not classical, allowing the classical pathway to function unhindered.

Cancer and the complement cascade

Despite significant research on the role of inflammation and immunosurveillance in the immunologic microenvironment of tumors, little attention has been given to the oncogenic capabilities of the complement cascade. The recent finding that complement may contribute to tumor growth suggests an insidious relationship between complement and cancer, especially in light of evidence that complement facilitates cellular proliferation and regeneration. We address the hypothesis that complement proteins promote carcinogenesis and suggest mechanisms by which complement can drive the fundamental features of cancer. Evidence shows that this diverse family of innate immune proteins facilitates dysregulation of mitogenic signaling pathways, sustained cellular proliferation, angiogenesis, insensitivity to apoptosis, invasion and migration, and escape from immunosurveillance. Given that the traditionally held functions for the complement system include innate immunity and cancer defense, our review suggests a new way of thinking about the role of complement proteins in neoplasia.