Expression of complement regulating factors in gastric cancer cells

Receptors and Host Factors for Enterovirus Infection: Implications for Cancer Therapy

Enteroviruses, with their diverse clinical manifestations ranging from mild or asymptomatic infections to severe diseases such as poliomyelitis and viral myocarditis, present a public health threat. However, they can also be used as oncolytic agents. This review shows the intricate relationship between enteroviruses and host cell factors. Enteroviruses utilize specific receptors and coreceptors for cell entry that are critical for infection and subsequent viral replication. These receptors, many of which are glycoproteins, facilitate virus binding, capsid destabilization, and internalization into cells, and their expression defines virus tropism towards various types of cells. Since enteroviruses can exploit different receptors, they have high oncolytic potential for personalized cancer therapy, as exemplified by the antitumor activity of certain enterovirus strains including the bioselected non-pathogenic Echovirus type 7/Rigvir, approved for melanoma treatment. Dissecting the roles of individual receptors in the entry of enteroviruses can provide valuable insights into their potential in cancer therapy. This review discusses the application of gene-targeting techniques such as CRISPR/Cas9 technology to investigate the impact of the loss of a particular receptor on the attachment of the virus and its subsequent internalization. It also summarizes the data on their expression in various types of cancer. By understanding how enteroviruses interact with specific cellular receptors, researchers can develop more effective regimens of treatment, offering hope for more targeted and efficient therapeutic strategies.

Effective clearance of rituximab-resistant tumor cells by breaking the mirror-symmetry of immunoglobulin G and simultaneous binding to CD55 and CD20

Complement-dependent cytotoxicity (CDC), which eliminates aberrant target cells through the assembly and complex formation of serum complement molecules, is one of the major effector functions of anticancer therapeutic antibodies. In this study, we discovered that breaking the symmetry of natural immunoglobulin G (IgG) antibodies significantly increased the CDC activity of anti-CD20 antibodies. In addition, the expression of CD55 (a checkpoint inhibitor in the CDC cascade) was significantly increased in a rituximab-resistant cell line generated in-house, suggesting that CD55 overexpression might be a mechanism by which cancer cells acquire rituximab resistance. Based on these findings, we developed an asymmetric bispecific antibody (SBU-CD55 × CD20) that simultaneously targets both CD55 and CD20 to effectively eliminate rituximab-resistant cancer cells. In various cancer cell lines, including rituximab-resistant lymphoma cells, the SBU-CD55 × CD20 antibody showed significantly higher CDC activity than either anti-CD20 IgG antibody alone or a combination of anti-CD20 IgG antibody and anti-CD55 IgG antibody. Furthermore, the asymmetric bispecific antibody (SBU-CD55 × CD20) exhibited significantly higher CDC activity against rituximab-resistant cancer cells compared to other bispecific antibodies with symmetric features. These results demonstrate that enhancing CDC with an asymmetric CD55-binding bispecific antibody could be a new strategy for developing therapeutics to treat patients with relapsed or refractory cancers.

Complement Regulatory Protein CD46 Manifests a Unique Role in Promoting the Migration of Bladder Cancer Cells

CD46 is a membrane-bound complement regulatory protein (mCRP) possessing a regulatory role with the complement system. CD46 protects the host cells from damage by complement. Expression of CD46 is also highly maintained in many cancers, including bladder cancers, and thus functions as a receptor for many cancer therapeutic viruses. In this study we report a unique role of CD46 as a progression factor of cancer cells in bladder cancers. Resulting data from a DNA microarray using CD46-altered HT1376 bladder cancers demonstrated a pool of target genes, including complement C3 α chain (C3α), matrix Gla protein (MGP), AFAP-AS1, follicular dendritic cell secreted protein (FDCSP), MAM domain containing 2 (MAMDC2), gamma-aminobutyric acid A receptor pi (GABRP), transforming growth factor, beta-induced (TGFBI), a family of cytochrome P450 (CYP24A1), sialic acid binding Ig-like lectin 6 (SIGLEC6), metallothionein 1E (MT1E), and several members of cytokeratins. Subsequent studies using quantitative RT-PCR and Western blot analyses confirmed CD46-mediated regulation of C3α, MGP, and keratin 13 (KRT13). MGP and KRT13 are known to be involved in cell migration and cancer cell metastasis. A cell migration assay demonstrated that CD46 enhanced migratory potential of bladder cancer cells. Taken all together, this report demonstrated that CD46 is generally overexpressed in bladder cancers and plays a unique role in the promotion of cancer cell migration. Further detailed studies are needed to be performed to clarify the action mechanism of CD46 and its application to cancer therapeutics.

CD46 protects the bladder cancer cells from cetuximab-mediated cytotoxicity

Epidermal growth factor receptor (EGFR) is an effective target for those patients with metastatic colorectal cancers that retain the wild-type RAS gene. However, its efficacy in many cancers, including bladder cancer, is unclear. Here, we studied the in vitro effects of cetuximab monoclonal antibodies (mAbs) targeting EGFR on the bladder cancer cells and role of CD46. Cetuximab was found to inhibit the growth of both colon and bladder cancer cell lines. Furthermore, cetuximab treatment inhibited AKT and ERK phosphorylation in the bladder cancer cells and reduced the expression of CD46 membrane-bound proteins. Restoration of CD46 expression protected the bladder cancer cells from cetuximab-mediated inhibition of AKT and ERK phosphorylation. We hypothesized that CD46 provides protection to the bladder cancer cells against mAb therapies. Bladder cancer cells were also susceptible to cetuximab-mediated immunologic anti-tumor effects. Further, cetuximab enhanced the cell killing by activating both antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) in bladder cancer cells. Restoration of CD46 expression protected the cells from both CDC and ADCC induced by cetuximab. Together, CD46 exhibited a cancer-protective effect against both direct (by involvement of PBMC or complement) and indirect cytotoxic activity by cetuximab in bladder cancer cells. Considering its clinical importance, CD46 could be an important link in the action mechanism of ADCC and CDC intercommunication and may be used for the development of novel therapeutic strategies.

Treatment of microvascular invasion in hepatocellular carcinoma with drug-loaded nanocomposite platform under synergistic effect of magnetic field/near-infrared light

Despite progress in clinical treatment, microvascular invasion (MVI) remains a major factor for frequent recurrence and metastasis of hepatocellular carcinoma (HCC) after liver resection and surgery. Thus, this study constructed a target nanoplatform (αCD97-USPIO-Au-DDP) with magnetic field/near-infrared (NIR) light response using ultrasmall superparamagnetic iron oxide-gold nanoporous spheres (USPIO-Au) as multifunctional nanocarrier. Anticancer drug cisplatin (DDP) was loaded, and specifically expressed CD97 protein in MVI was taken as the therapeutic target. The αCD97-USPIO-Au-DDP showed favorable photothermal and stable properties under the NIR light at 808 nm wavelength. As suggested by in vitro and in vivo research, this composite nanopreparation could effectively reduce damage to normal organs and showed good biocompatibility. Excellent magnetic targeting function of nanocarrier and modification of αCD97 strengthened accumulation of composite nanodrug in tumor to inhibit tumor growth. This system may have important ramifications for treatment of MVI in HCC.

Trastuzumab/Pertuzumab combination therapy stimulates anti-tumor responses through complement-dependent cytotoxicity and phagocytosis

Standard-of-care treatment for advanced HER2+ breast cancers (BC) is comprised of two HER2-specific monoclonal antibodies (mAb), Trastuzumab (T) and Pertuzumab (P) with chemotherapy. While this combination (T+P) is highly effective, its synergistic mechanism of action (MOA) is not completely known. Initial studies had demonstrated that Pertuzumab suppressed HER2 hetero-dimerization as the potential therapeutic MOA, thus the improved outcome associated with the T+P combination MOA compared to Trastuzumab alone has been widely reported as being due to Pertuzumab-mediated suppression of HER2 signaling in combination with Trastuzumab-mediated induction of anti-tumor immunity. Unraveling this MOA may be critical to extend this combination strategy to other antigens or other cancers, as well as improving this current treatment modality. Using novel murine and human versions of Pertuzumab, we found it induced both Antibody-Dependent-Cellular-Phagocytosis (ADCP) by tumor-associated macrophages and suppression of HER2 oncogenic signaling. Most significantly, we identified that only T+P combination therapy, but not when either antibody used in isolation, allows for the activation of the classical complement pathway, resulting in both direct complement-dependent cytotoxicity (CDC) as well as complement-dependent cellular phagocytosis (CDCP) of HER2+ BC cells. Notably, we show that tumor expression of C1q was positively associated with survival outcome in HER2+ BC patients, whereas expression of complement regulators CD55 and CD59 were inversely correlated, suggesting the importance of complement activity in clinical outcomes. Accordingly, inhibition of C1 activity in mice abolished the synergistic therapeutic activity of T+P therapy, whereas knockdown of CD55 and CD59 expression enhanced T+P efficacy. In summary, our study identifies classical complement activation as a significant anti-tumor MOA for T+P therapy that may be functionally enhanced to augment therapeutic efficacy in the clinic.

Mechanisms of Therapeutic Antitumor Monoclonal Antibodies

Monoclonal antibodies (mAb) are a major component of cancer therapy. In this review, we summarize the different therapeutic mAbs that have been successfully developed against various tumor-expressed antigens and examine our current understanding of their different mechanisms of antitumor action. These mechanisms of action (MOA) largely center on the stimulation of different innate immune effector processes, which appear to be principally responsible for the efficacy of most unconjugated mAb therapies against cancer. This is evident in studies of mAbs targeting antigens for hematologic cancers, with emerging data also demonstrating the critical nature of innate immune-mediated mechanisms in the efficacy of anti-HER2 mAbs against solid HER2+ cancers. Although HER2-targeted mAbs were originally described as inhibitors of HER2-mediated signaling, multiple studies have since demonstrated these mAbs function largely through their engagement with Fc receptors to activate innate immune effector functions as well as complement activity. Next-generation mAbs are capitalizing on these MOAs through improvements to enhance Fc-activity, although regulation of these mechanisms may vary in different tumor microenvironments. In addition, novel antibody-drug conjugates have emerged as an important means to activate different MOAs. Although many unknowns remain, an improved understanding of these immunologic MOAs will be essential for the future of mAb therapy and cancer immunotherapy.

Proteomic Profiling of Gastric Signet Ring Cell Carcinoma Tissues Reveals Characteristic Changes of the Complement Cascade Pathway

Signet ring cell carcinoma (SRCC) is a histological subtype of gastric cancer with distinct features in multiple aspects compared with adenocarcinomas (ACs). The lack of a systematic molecular overview of this disease has led to slow progress in its clinical practice. In the present proteomics study, gastric tissues were collected from tumors and adjacent tissues, including 14 SRCCs and 34 ACs, and laser capture microdissection (LCM) was employed to eradicate the cellular heterogeneity of the tissues. The proteomes of tissues were profiled by data-independent acquisition (DIA) mass spectrometry (MS). Based on the over 6000 proteins quantified, univariate analysis and pathway enrichment revealed that some proteins and pathways demonstrated differences between SRCC and ACs. Importantly, the upregulation of a majority of complement-related proteins was notable for SRCC but not for ACs. A hypothesis, based on the proteomics evidence, was proposed that the complement cascade was evoked in the SRCC microenvironment upon infiltration, and the SRCC cells survived the complement cytotoxicity by secreting endogenous negative regulators. Moreover, an attempt was made to establish appropriate cell models for gastric SRCC through proteomic comparison of the 15 gastric cell lines and gastric tumors. The predictions of a supervised classifier suggested that none of these gastric cell lines qualified to mimic SRCC. This study discovered that the complement cascade is activated at a higher level in gastric SRCC than in ACs.

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LCM-DIA extracted unprecedented proteomic details of gastric in different subtypes.

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Complement cascade was found to be an SRCC-specific pathway for the first time.

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Gastric cell lines were evaluated based on proteomic features for the first time.

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Re-analyzable DIA data collected provide rich opportunity for future research.

Evaluation of Ficolin-3 as a Potential Prognostic Serum Biomarker in Chinese Patients with Esophageal Cancer

Aims: Ficolin-3 is a circulating pattern recognition molecule of the lectin pathway, which participates in the host immune responses to cancer. Our study aimed to evaluate the prognostic efficacy of ficolin-3 in patients with esophageal cancer (EC). Methods: A total of 233 patients with EC were recruited for this study during a period from March 2013 to March 2016. Clinical information and pretherapeutic tumor specimens from all of the patients were analyzed. Serum ficolin-3 levels were determined by enzyme-linked immunosorbent assay. Patients were then assigned into quartiles according to their serum ficolin-3 levels. The Cox proportional hazards model was utilized to explore the correlation between ficolin-3 levels with overall survival (OS) and disease-specific survival (DSS). Results: The serum ficolin-3 level in the esophageal squamous cell carcinoma (ESCC) group was significantly higher than in the esophageal adenocarcinoma (EAC) group (19.59 ± 4.35 ng/mL vs. 18.39 ± 5.42 ng/mL, p < 0.01). There were great differences in prevalence of ESCC, tumor length, involvement of adventitia, and lymph node status among patients in different ficolin-3 groups (all p < 0.01). Both univariate analyses and further multivariate analyses revealed the close association between ficolin-3 levels and EAC (For OS and DSS, all p < 0.05). Out of 233 patients, survival information was available for 220, including 100 (45.45%) females and 120 (54.54%) males. When dividing the ficolin-3 levels into quartiles, patients with higher serum ficolin-3 levels showed a trend toward longer OS and DSS no matter whether they were diagnosed as ESCC or EAC (HR 0.21-0.55, all p < 0.05). Conclusions: Serum ficolin-3 levels were identified as an independent prognostic biomarker for DSS and OS in Chinese patients with EC, especially EAC.

Virus-Receptor Interactions: Structural Insights For Oncolytic Virus Development

Recent advancements in oncolytic virotherapy commend a special attention to developing new strategies for targeting cancer cells with oncolytic viruses (OVs). Modifications of the viral envelope or coat proteins serve as a logical mean of repurposing viruses for cancer treatment. In this review, we discuss how detailed structural knowledge of the interactions between OVs and their natural receptors provide valuable insights into tumor specificity of some viruses and re-targeting of alternate receptors for broad tumor tropism or improved tumor selectivity.

Overexpression of CD55 correlates with tumor progression and poor prognosis in gastric stromal tumors

Backgrounds: Accumulating evidences have demonstrated that CD55 can protect cells from complement-mediated attack, and is involved in tumor dedifferentiation, migration, invasiveness, and metastasis. However, the role of CD55 in gastrointestinal stromal tumors (GISTs) has not been investigated. Aims: Our study aimed to analyze the expression of CD55 in gastric GISTs and its correlations with clinicopathologic characteristics and prognosis. Materials and methods: A total of 118 gastric GIST patients were included in our study. CD55 expression in GIST tissue samples was evaluated using immunohistochemistry. Cumulative survival was conducted using the Kaplan-Meier method. Cox regression analyses were performed to identify factors associated with progression-free survival (PFS) for patients with gastric GISTs. Results: Of 118 gastric GISTs patients included in our study, 44 (37.3%) were positive for CD55 expression. Positive CD55 expression in gastric GISTs was closely associated with tumor size (13.52±7.35 vs 5.07±1.90 cm, respectively; P<0.001), Ki 67 labeling index (P=0.001), mitotic counts (P=0.005), NIH risk classification (P<0.001), PLR (P<0.001), and metastasis at initial diagnosis (P=0.002). Kaplan-Meier analyses revealed that tumor size (P<0.001), mitotic counts (P<0.001), Ki 67 labeling index (P<0.001), PLR (P<0.001), metastasis at initial diagnosis (P=0.031), and CD55 expression (P<0.001) were statistically significant risk factors affecting PFS of patients with gastric GISTs. Cox multivariate survival analysis showed that mitotic counts, Ki 67 labeling index, and CD55 expression were independent predictors of PFS for gastric GISTs. Conclusion: CD55 may be a potential prognostic marker in gastric GISTs patients.

Role of C5b-9 and RGC-32 in Cancer

The complement system represents an effective arsenal of innate immunity as well as an interface between innate and adaptive immunity. Activation of the complement system culminates with the assembly of the C5b-9 terminal complement complex on cell membranes, inducing target cell lysis. Translation of this sequence of events into a malignant setting has traditionally afforded C5b-9 a strict antitumoral role, in synergy with antibody-dependent tumor cytolysis. However, in recent decades, a plethora of evidence has revised this view, highlighting the tumor-promoting properties of C5b-9. Sublytic C5b-9 induces cell cycle progression by activating signal transduction pathways (e.g., Gi protein/ phosphatidylinositol 3-kinase (PI3K)/Akt kinase and Ras/Raf1/ERK1) and modulating the activation of cancer-related transcription factors, while shielding malignant cells from apoptosis. C5b-9 also induces Response Gene to Complement (RGC)-32, a gene that contributes to cell cycle regulation by activating the Akt and CDC2 kinases. RGC-32 is expressed by tumor cells and plays a dual role in cancer, functioning as either a tumor promoter by endorsing malignancy initiation, progression, invasion, metastasis, and angiogenesis, or as a tumor suppressor. In this review, we present recent data describing the versatile, multifaceted roles of C5b-9 and its effector, RGC-32, in cancer.

Decay-accelerating factor promotes endometrial cells proliferation and motility under ovarian hormone stimulation

The intent of the study was to explore the elevating expression of decay-accelerating factor(DAF) exerts influence on biological behaviors of endometrial stromal cells except in classical immunology on the basis of bioinformatic statistics and clinical miscarriages findings suggesting its potential role in the establishment of endometrial receptivity. We confirmed that DAF locates on the cellular surface of endometrial epithelium and stroma. By using plasmid transfection to down-regulate DAF expression in primary endometrial stromal cells(ESCs), we discovered that DAF expression in ESCs increases in response to estradiol and progesterone stimulation in dose- and time-dependent manners; moreover, tamoxifen and RU486 stimulations to block estrogen receptors(ERs) and progesterone receptors(PRs) respectively result in reduced DAF mRNA and protein, and it is more obvious to block PRs. Meanwhile, knocked-down DAF in ESCs weakens the proliferation, migration and invasion of endometrial cells. Cell cycle analysis showed knocked-down DAF accumulates cells in S phase and diminishes cells in G0/G1 phase, which substantiates DAF mediates endometrial cells proliferation. In conclusion, DAF is a potential molecule involving in endometrial cellular proliferation and motility to verify up-expressed DAF during the WOI may facilitate endometrial physiobiological behavior changes, which shed light on DAF function and potential role in the endometrial receptivity establishment.

Development of a radionuclide-labeled monoclonal anti-CD55 antibody with theranostic potential in pleural metastatic lung cancer

Decay-accelerating factor (CD55 or DAF) inhibits complement-dependent cytotoxicity. We determined that CD55 is overexpressed in 76.47% of human non-small cell lung cancer tissue specimens. We therefore developed a lutetium-177-labeled chimeric monoclonal antibody against CD55. CD55-specific single-chain variable fragment (scFv) was selected from a naïve chicken scFv phage-display library, converted to IgG, and radiolabeled with lutetium-177 to generate a ¹⁷⁷Lu-anti-CD55 antibody. We then charaterized the biodistribution of this antibody in a mouse model of pleural metastatic lung cancer. The ¹⁷⁷Lu-anti-CD55 antibody was primarily retained in tumor tissue rather than normal tissue. Treatment of the mice with ¹⁷⁷Lu-anti-CD55 reduced the growth of lung tumors and improved median survival in vivo by two-fold compared to controls. Finally, ¹⁷⁷Lu-anti-CD55 also enhanced the antitumor activity of cisplatin both in vitro and in vivo. These data suggest ¹⁷⁷Lu-anti-CD55 antibody is a promising theranostic agent for pleural metastatic lung cancer.

CD59: a promising target for tumor immunotherapy

CD59 has been identified as a glycosylphosphatidylinositol-anchored membrane protein that acts as an inhibitor of the formation of the membrane attack complex to regulate complement activation. Recent studies have shown that CD59 is highly expressed in several cancer cell lines and tumor tissues. CD59 also regulates the function, infiltration and phenotypes of a variety of immune cells in the tumor microenvironment. Herein, we summarized recent advances related to the functions and mechanisms of CD59 in the tumor microenvironment. Therapeutic strategies that seek to modulate the functions of CD59 in the tumor microenvironment could be a promising direction for tumor immunotherapy.

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.

Prognostic Significance of Preoperative and Postoperative Complement C3 Depletion in Gastric Cancer: A Three-Year Survival Investigation

OBJECTIVES

The role of complement system in predicting prognosis of gastric cancer (GC) remains obscured. This study aims to explore the incidence of complement C3 depletion and associated outcomes in GC patients.

METHODS

between August 2013 and December 2013, 106 patients with gastric adenocarcinoma were prospectively analyzed. Plasma levels of complement C3 and C4 were detected at baseline, one day before surgery, and postoperative day 3, respectively. Patients with low C3 levels (<0.75 mg/mL) were considered as having complement depletion (CD), while others with normal C3 levels were included as control. The 3-year overall survival (OS), disease-free survival (DFS), and other outcomes were compared between both groups, with the CD incidence explored meanwhile.

RESULTS

The CD incidence was 28.3% before surgery but increased to 37.7% after surgery. Preoperative CD was related to prolonged hospital stay (22.7 versus 19.2 day, P = 0.032) and increased postoperative complications (33.3% versus 14.5%, P = 0.030) and hospital costs (P = 0.013). Besides, postoperative C3 depletion was significantly associated with decreased 3-year OS (P = 0.022) and DFS (P = 0.003). Moreover, postoperative C3 depletion and advanced tumor stage were independent predictive factors of poor prognosis.

CONCLUSIONS

Complement C3 depletion occurring in gastric cancer was associated with poor short-term and long-term outcomes.

Employing RNA viruses to fight cancer: novel insights into oncolytic virotherapy

Within recent decades, viruses that specifically target tumor cells have emerged as novel therapeutic agents against cancer. These viruses do not only act via their cell-lytic properties, but also harbor immunostimulatory features to re-direct the tumor microenvironment and stimulate tumor-directed immune responses. Furthermore, oncolytic viruses are considered to be superior to classical cancer therapies due to higher selectivity towards tumor cell destruction and, consequently, less collateral damage of non-transformed healthy tissue. In particular, the field of oncolytic RNA viruses is rapidly developing since these agents possess alternative tumor-targeting strategies compared to established oncolytic DNA viruses. Thus, oncolytic RNA viruses have broadened the field of virotherapy facilitating new strategies to fight cancer. In addition to several naturally occurring oncolytic viruses, genetically modified RNA viruses that are armed to express foreign factors such as immunostimulatory molecules have been successfully tested in early clinical trials showing promising efficacy. This review aims to provide an overview of the most promising RNA viruses in clinical development, to summarize the current knowledge of clinical trials using these viral agents, and to discuss the main issues as well as future perspectives of clinical approaches using oncolytic RNA viruses.

Overexpression of CD55 from Barrett's esophagus is associated with esophageal adenocarcinoma risk

BACKGROUND AND AIM

Although several molecular biomarkers for esophageal adenocarcinoma (EAC) have been shown to be useful disease indicators, none has been established as a reliable indicator for risk of EAC or have progressed to routine use. The aim was to identify biomarkers of high risk for EAC in patients with Barrett's esophagus (BE).

METHODS

Following endoscopic observation by magnified endoscopy with narrow band imaging (ME-NBI), brushing was followed by obtaining biopsy samples from columnar-lined esophagus (CLE) and from EAC lesions of EAC patients, and from age- and sex-matched non-EAC controls with BE. Total RNA was extracted for microarray analysis using Affymetrix GeneChip Human Genome U133 plus 2.0 Array. Real-time-PCR analysis of identified candidate genes was used to confirm the results.

RESULTS

Overall, 9 EAC patients and 50 patients with BE were studied. Seventy-nine candidate genes were identified by microarray analysis based on a proportional hazards model (P < 0.005). Six genes exhibited significantly differential expressions in both BE and cancer lesions of the EAC group compared to BE of the controls. In the brushing samples, median CD55 relative expression levels in cancer lesions were highest and decreased in BE of EAC group and BE of the controls, in that order (P < 0.001).

CONCLUSION

Over expression of CD55 in brushing samples taken from BE may be associated with the risk of EAC.

The tag SNP rs10746463 in decay-accelerating factor is associated with the susceptibility to gastric cancer

BACKGROUND

Complement activation involved in the innate immunity and adaptive immunity and further contributed to the development of tumor growth. This study aimed to investigate the association of genetic variants in complement 3 (C3) and decay-accelerating factor (DAF) genes with the risk of gastric cancer.

METHODS

This case-control study included 500 gastric cancer patients and 500 cancer-free controls. Based on the Chinese population data from HapMap database, we used Haploview 4.2 program to select candidate tag SNPs. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by logistic regression to evaluate the association of each genetic variant with the risk of gastric cancer.

RESULTS

Among 12 tag SNPs of C3, no correlation was observed between C3 genetic variants and risk of gastric cancer. For tag SNPS of DAF, logistic regression analysis revealed that the carriers with DAF rs10746463 AA genotype had a significantly increased risk for developing gastric cancer (OR = 1.46, 95% CI = 1.01–2.10) when compared with GG genotype, but those carrying with rs10746463 AG genotype didn't (OR = 1.31, 95% CI = 0.98-1.75). When stratified by smoking status, we found that the risk of gastric cancer was associated with rs10746463 GA or AA genotype carriers among smoker with OR (95% CI) of 1.64 (1.06-2.54), but not among non-smoker (OR = 1.37, 95% CI = 0.97-1.94).

CONCLUSION

DAF rs10746463 polymorphism effects on the risk of developing gastric cancer in Chinese population.

Regulation of complement and modulation of its activity in monoclonal antibody therapy of cancer

The complement system is a powerful tool of the innate immune system to eradicate pathogens. Both in vitro and in vivo evidence indicates that therapeutic anti-tumor monoclonal antibodies (mAbs) can activate the complement system by the classical pathway. However, the contribution of complement to the efficacy of mAbs is still debated, mainly due to the lack of convincing data in patients. A beneficial role for complement during mAb therapy is supported by the fact that cancer cells often upregulate complement-regulatory proteins (CRPs). Polymorphisms in various CRPs were previously associated with complement-mediated disorders.

In this review the role of complement in anti-tumor mAb therapy will be discussed with special emphasis on strategies aiming at modifying complement activity. In the future, clinical efficacy of mAbs with enhanced effector functions together with comprehensive analysis of polymorphisms in CRPs in mAb-treated patients will further clarify the role of complement in mAb therapy.

Role of C5b-9 complement complex and response gene to complement-32 (RGC-32) in cancer

Complement system activation plays an important role in both innate and acquired immunity, with the activation of complement and the subsequent formation of C5b-9 terminal complement complex on cell membranes inducing target cell death. Recognition of this role for C5b-9 leads to the assumption that C5b-9 might play an antitumor role. However, sublytic C5b-9 induces cell cycle progression by activating signal transduction pathways and transcription factors in cancer cells, indicating a role in tumor promotion for this complement complex. The induction of the cell cycle by C5b-9 is dependent upon the activation of the phosphatidylinositol 3-kinase (PI3K)/Akt/FOXO1 and ERK1 pathways in a Gi protein-dependent manner. C5b-9 also induces response gene to complement (RGC)-32, a gene that plays a role in cell cycle promotion through activation of Akt and the CDC2 kinase. RGC-32 is expressed by tumor cells and plays a dual role in cancers, in that it has both a tumor suppressor role and tumor-promoting activity. Thus, through the activation of tumor cells, the C5b-9-mediated induction of the cell cycle plays an important role in tumor proliferation and oncogenesis.

The invasion and metastasis promotion role of CD97 small isoform in gastric carcinoma

CD97 is over-expressed in the majority of gastric adenocarcinomas and is associated with its dedifferentiation and aggressiveness. Our previous results demonstrated that out of three CD97 isoforms tested, only the small one was able to promote increased invasiveness in vitro. Based on these data we further aimed to investigate the role of CD97 small isoform in gastric cancer progression in vivo by employing the cells with a stable CD97 small isoform knock-down and an orthotopic gastric cancer mouse model. We could demonstrate that the knock down of CD97/EGF1,2,5, led to a significant decrease in the number of cells penetrating the gelatin coated membrane as compared with control cells. In the gastric cancer mouse model, both the hypodermic and the orthotopic yielded tumor masses of the CD97/EGF1,2,5kd group and were significantly smaller than the control. Metastatic tumor cell number in early metastatic regional lymph nodes on post-operative day 42 was distinctly decreased in the CD97/EGF1,2,5kd group as compared with the SGC-NS group, and was accompanied with the downregulation of CD44, VEGFR, CD31 and CD97. We concluded in this study that CD97 small isoform not only supported gastric cancer local growth, but also promoted metastatic spread in orthotopically implanted mouse model suggesting involvement of the CD97 small isoform in the preparation of (pre)metastatic niche.

HBXIP upregulates CD46, CD55 and CD59 through ERK1/2/NF-κB signaling to protect breast cancer cells from complement attack

Hepatitis B X-interacting protein (HBXIP) is able to enhance migration of breast cancer cells. However, the role of HBXIP in regulation of complement-dependent cytotoxicity (CDC) in breast cancer is not understood. Here, we report that HBXIP contributes to protecting breast cancer cells from CDC by upregulating membrane-bound complement regulatory protein (mCRPs), including CD46, CD55 and CD59. We found that HBXIP upregulated mCRPs through activating p-ERK1/2/NF-κB. Interestingly, the knockdown of CD59 was able to block the HBXIP-enhanced breast tumor growth in animal. Thus, we conclude that HBXIP upregulates CD46, CD55 and CD59 through p-ERK1/2/NF-κB signaling to protect breast cancer from CDC.

Membrane attack by complement: the assembly and biology of terminal complement complexes

Complement system activation plays an important role in both innate and acquired immunity. Activation of the complement and the subsequent formation of C5b-9 channels (the membrane attack complex) on the cell membranes lead to cell death. However, when the number of channels assembled on the surface of nucleated cells is limited, sublytic C5b-9 can induce cell cycle progression by activating signal transduction pathways and transcription factors and inhibiting apoptosis. This induction by C5b-9 is dependent upon the activation of the phosphatidylinositol 3-kinase/Akt/FOXO1 and ERK1 pathways in a Gi protein-dependent manner. C5b-9 induces sequential activation of CDK4 and CDK2, enabling the G1/S-phase transition and cellular proliferation. In addition, it induces RGC-32, a novel gene that plays a role in cell cycle activation by interacting with Akt and the cyclin B1-CDC2 complex. C5b-9 also inhibits apoptosis by inducing the phosphorylation of Bad and blocking the activation of FLIP, caspase-8, and Bid cleavage. Thus, sublytic C5b-9 plays an important role in cell activation, proliferation, and differentiation, thereby contributing to the maintenance of cell and tissue homeostasis.

RNA interference characterization of proteins discovered by proteomic analysis of pancreatic cancer reveals function in cell growth and survival

OBJECTIVES

There is a clear need for better therapeutics and diagnostics for pancreatic cancer. We aimed to discover plasma membrane-associated proteins overexpressed in pancreatic cancer using quantitative proteomics and apply RNA interference (RNAi) to uncover proteins associated with cancer cell survival.

METHODS

Cell surface glycoproteins from 5 pancreatic cancer cell lines were isolated, and differential analyses were performed using mass spectrometry and the "normoid" cell line Hs766T as the comparator. For validation, immunohistochemistry was performed on tissues from 10 independent patients and 2 normal donors. Correlation of protein and mRNA expression level was determined, and functional activity characterized using RNAi.

RESULTS

Integrin β6, CD46, tissue factor, and a novel protein, chromosome 14 open reading frame 1, were identified as overexpressed on pancreatic cancer cell lines. Immunohistochemistry demonstrated the 4 targets were overexpressed in 20% to 70% of primary pancreatic tumor specimens. Small interfering RNA knockdown resulted in a reduction of cellular proliferation by inhibiting DNA synthesis, blocking S-phase progression or induction of apoptosis.

CONCLUSIONS

By combining a mass spectrometry identification platform and an RNAi validation platform, we have identified a panel of cell surface glycoproteins that not only are overexpressed, but also play a functional role in pancreatic tumor cell survival.

The complement regulator CD46 is bactericidal to Helicobacter pylori and blocks urease activity

BACKGROUND & AIMS

CD46 is a C3b/C4b binding complement regulator and a receptor for several human pathogens. We examined the interaction between CD46 and Helicobacter pylori (a bacterium that colonizes the human gastric mucosa and causes gastritis), peptic ulcers, and cancer.

METHODS

Using gastric epithelial cells, we analyzed a set of H pylori strains and mutants for their ability to interact with CD46 and/or influence CD46 expression. Bacterial interaction with full-length CD46 and small CD46 peptides was evaluated by flow cytometry, fluorescence microscopy, enzyme-linked immunosorbent assay, and bacterial survival analyses.

RESULTS

H pylori infection caused shedding of CD46 into the extracellular environment. A soluble form of CD46 bound to H pylori and inhibited growth, in a dose- and time-dependent manner, by interacting with urease and alkyl hydroperoxide reductase, which are essential bacterial pathogenicity-associated factors. Binding of CD46 or CD46-derived synthetic peptides blocked the urease activity and ability of bacteria to survive in acidic environments. Oral administration of one CD46 peptide eradicated H pylori from infected mice.

CONCLUSIONS

CD46 is an antimicrobial agent that can eradicate H pylori. CD46 peptides might be developed to treat H pylori infection.

Effect of periodontopathogen lipopolysaccharides and proinflammatory cytokines on CD46, CD55, and CD59 gene/protein expression by oral epithelial cells

Membrane-anchored complement regulatory proteins (CRPs), including CD46, CD55, and CD59, protect host cells from complement attack. In the present study, we investigated whether periodontopathogen lipopolysaccharide and proinflammatory cytokines modulate CRP gene/protein expression in human oral epithelial cells. The lipopolysaccharide of Treponema denticola and Tannerella forsythia were the most potent for increasing the gene expression of CD55 and CD59, and to a lesser extent CD46, after a 48-h stimulation. An lipopolysaccharide-induced upregulation of epithelial cell-surface CRP was also demonstrated. The stimulation of epithelial cells with lipopolysaccharide was associated with interleukin-6 (IL-6) and IL-8 secretion. Although these two cytokines had no effect on CD46 and CD55 gene expression in epithelial cells, IL-1β and tumor necrosis factor-α induced a significant upregulation. The cell-surface expression of CRP was also increased by the stimulation of epithelial cells with cytokines. The CD46, CD55, and CD59 gene/protein expression was upregulated by periodontopathogen lipopolysaccharide and proinflammatory cytokines. It can be hypothesized that, when faced with bacterial challenges and inflammatory conditions associated with active periodontal sites, oral epithelial cells may respond by increasing CRP gene/protein expression to avoid cell lysis by the complement system, which is activated during periodontitis.

Suppression of tumorigenesis: modulation of inflammatory cytokines by oral administration of microencapsulated probiotic yogurt formulation

The objective of this study was to examine the ability of a novel microencapsulated probiotic yogurt formulation to suppress the intestinal inflammation. We assessed its anticancer activity by screening interleukin-1, 6, and 12 (IL-1, 6, 12), secretory levels of tumor necrosis factor-alpha (TNF-α), interferon-gamma (IFN-γ), prostaglandin E(2)  (PGE(2)), and thromboxane B2 in the digesta obtained from the duodenum, jejunum, proximal, and distal segments of the ileum of C57BL/6J-Apc(Min)/J mice. Formulation-receiving animals showed consistently lower proinflammatory cytokines' levels when compared to control group animals receiving empty alginate-poly-L-lysine-alginate (APA) microcapsules suspended in saline. The concentrations of IL-12 found in serum in control and treatment group animals were significant: 46.58 ± 16.96 pg/mL and 158.58 ± 28.56 pg/mL for control and treatment animals, respectively. We determined a significant change in plasma C-reactive protein: 81.04 ± 23.73 ng/mL in control group and 64.21 ± 16.64 ng/mL in treatment group. Western blots showed a 71% downregulation of cyclooxygenase-2 (COX-2) protein in treatment group animals compared to control. These results point to the possibility of using this yogurt formulation in anticancer therapies, in addition to chronic gut diseases such as Crohn's disease, irritable bowel syndrome (IBS), and inflammatory bowel disease (IBD) thanks to its inflammation lowering properties.

Expression of complement restriction factors (CD46, CD55 & CD59) in head and neck squamous cell carcinomas

BACKGROUND

Tumor cells can escape complement-dependent cytotoxicity (CDC) by expressing complement restriction factors (CRFs), CD46, CD55 and CD59. CRF-expression in non-neoplastic mucosa of the head and neck was compared with biopsies of the head and neck squamous cell carcinoma (HNSCC) and cell lines derived from oral squamous cell carcinomas (OSCC).

METHODS

Normal mucosa and HNSCC tumor tissue (poor, moderate, or well differentiated) specimens were immunostained with anti-CRF monoclonal antibodies. Immunostaining of the OSCC cell lines (SCC12 and SCC71) was examined under laser scan fluorescence microscopy.

RESULTS

CD46, CD55 and CD59 were highly expressed in HNSCC cells including T1/T2N0M0 stages. The CRF expression was much lower or absent in non-neoplastic squamous epithelia or in the submucosa of both normal and tumor tissues.

CONCLUSIONS

Enhanced staining of tumor tissues at stages T1/T2 indicates that the CRFs are overexpressed by primary tumors before metastasis to either lymph nodes or organs (N0M0 stage) suggesting that CRFs are formed early during tumorigenesis.

Identification of the decay-accelerating factor CD55 as a peanut agglutinin-binding protein and its alteration in non-small cell lung cancers

PURPOSE

Peanut agglutinin (PNA) recognizes tumor-associated carbohydrates. In this study, we aimed to identify the core protein harboring PNA-binding sugars in the human lung and to explore the relationship with the pathology of primary non-small cell lung cancers (NSCLC).

EXPERIMENTAL DESIGN

PNA lectin blotting was used to detect PNA-binding proteins in the microsomal fraction of lung tissue from 24 patients with NSCLC. The 55- to 65-kDa core peptide PNA-binding protein was characterized by enzymatic treatment and identified by immunoprecipitation and affinity chromatography. The expression level and increase in size of the 55- to 65-kDa PNA-binding protein/decay-accelerating factor (DAF) were compared between normal and tumor regions of the tumor tissue by Western blotting and quantitative PCR.

RESULTS

The 55- to 65-kDa PNA-binding protein was observed in human lung. This was a glycosylphosphatidylinositol-anchored membrane protein carrying O-linked carbohydrates. This core protein was identified as DAF, one of the complementary regulatory proteins. DAF was enlarged to 65 to 75 kDa in NSCLC tumor lesions due to sialylation in the sugar moiety. At the transcription level, DAF levels were significantly lower in tumor regions, suggesting its down-regulation in NSCLC cells.

CONCLUSIONS

DAF was identified as a new PNA-binding protein in the human lung. The down-regulation and heavy sialylation of DAF was associated with pathology in NSCLC, and these alterations make this protein a potential marker for NSCLC.

Complement decay accelerating factor (DAF)/CD55 in cancer

The complement system is a powerful innate mechanism involved in protection of the host against pathogens. It also has a role in the clearance of apoptotic cells and has been implicated in a range of pathologies including autoimmunity and graft rejection. The control of complement is mediated through the complement regulatory proteins (CRPs). These are present on most cells and protect normal cells from complement-mediated attack during innate activation. However, in a range of pathologies and cancer, these molecules are up or down regulated, sometimes secreted and even lost. We will review the expression of CRPs in cancer, focussing on CD55 and highlight other roles of the CRPs and their involvement in leukocyte function. We will also provide some data providing a potential mechanism by which soluble CD55 can inhibit T-cell function and discuss some of the implications of this data.

Expression of the membrane complement regulatory protein CD59 (protectin) is associated with reduced survival in colorectal cancer patients

It has been known for some time that the immune system can recognise growing tumours, and that tumours may respond by modulation of molecules, which make them resistant to further attack. Expression, over-expression, or loss of these molecules may function as markers of tumour progression and prognosis. Among such molecules are the membrane-bound complement regulatory proteins (mCRP), which protect cells from bystander attack by autologous complement. These include CD59 (protectin), which prevents formation of the MAC complex in the terminal stages of complement activation. In the present study, we evaluated immunohistochemical expression of CD59 in a series of over 460 well-characterised colorectal cancers using tissue microarrays (TMA), and related this information to known tumour and patient variables and to survival. The CD59 expression was observed in 69 (15%) of cases overall, and was significantly associated with tumour grade. In contrast, no associations were noted with tumour site, stage or histological type. On survival analysis, a further correlation was observed between expression of CD59 by the colorectal tumours and a reduction in disease-specific patient survival. This observation was strongest for patients with early stage disease. However, a negative impact on survival was also seen in those patients with late stage disease. These results indicate that TMA linked to good clinicopathological databases with good long term follow up are useful tools for determining new prognostic indicators that can be used in future patient management. Immune surveillance may result in immune-editing that induces variable expression of a range of target antigens, and these may be useful prognostic markers. This study has identified CD59 expression as a marker of poor prognosis in colorectal cancer patients.

Decay-accelerating factor (CD55): a versatile acting molecule in human malignancies

The decay-accelerating factor (DAF, CD55) physiologically serves as an inhibitor of the complement system. Moreover, DAF is broadly expressed in malignant tumors. Here, DAF seems to dispose of several different functions reaching far beyond its immunological role, e.g., promotion of tumorigenesis, decrease of complement mediated tumor cell lysis, autocrine loops for cell rescue and evasion of apoptosis, neoangiogenesis, invasiveness, cell motility, and metastasis via oncogenic tyrosine kinase pathway activation, and specific seven-span transmembrane receptors (CD97) binding. Furthermore, DAF has already been included in diagnostic or therapeutic studies. Thereby, studies applying monoclonal anti-DAF antibodies and anti-DAF vaccination for a targeted therapy have been enrolled recently.

Helicobacter pylori eradication decreases the expression of glycosylphosphatidylinositol-anchored complement regulators, decay-accelerating factor and homologous restriction factor 20, in human gastric epithelium

BACKGROUND

It has previously been reported that there is a strong correlation between the expression of glycosylphosphatidylinositol (GPI)-anchored complement membrane inhibitor in gastric epithelium and the severity of inflammation of gastric mucosa. To investigate the regulation of complement activity in gastric epithelium during Helicobacter pylori (H. pylori)-associated gastritis, the expression of GPI-anchored complement membrane inhibitors, decay-accelerating factor (DAF) and 20-kDa homologous restriction factor 20 (HRF20), and membrane cofactor protein (MCP), which is a transmembrane protein, were evaluated after removal of the H. pylori stimulus. Furthermore, the expression of the complement fragment, C3c, was also investigated.

METHODS

Forty-six patients with epigastric symptoms and endoscopically confirmed peptic ulcer or gastritis who had H. pylori infection of the gastric mucosa were enrolled in the present study. Biopsy specimens were obtained from the gastric antrum and corpus 1 month before and after eradication. Helicobacter pylori infection was determined by the rapid urease test, histology, and culture before eradication, and by histology, culture, and urea breath test after eradication. Gastric biopsy specimens obtained before and after eradication were evaluated for infiltration by neutrophils and mononuclear cells. The expression of complement membrane inhibitors, DAF, HRF20, and MCP and that of the main complement fragment, C3c, was immunohistochemically evaluated.

RESULTS

One month after the eradication of H. pylori, the infiltration by neutrophils and mononuclear cells in the gastric mucosa decreased significantly (P < 0.0001) as compared with that before eradication. The expression of DAF, HRF20, and C3c on gastric mucosal epithelium also significantly decreased in both the antrum and the corpus (P < 0.05) 1 month after eradication. However, no change was observed in the expression of MCP.

CONCLUSIONS

The decrease in the expression of GPI-anchored complement regulator and the complement after removal of a chronic microbial stimulus suggests that the gastric epithelium appears to undergo an aggressive stress of complement during H. pylori infection. Conclusively, DAF and HRF20 may play an important protective role against complement-mediated damage induced by chronic microbial stimuli in such a pathological condition.

Selective expression of a splice variant of decay-accelerating factor in c-erbB-2-positive mammary carcinoma cells showing increased transendothelial invasiveness

By differential-display-PCR a subclone of the SK-BR-3 cell line with high in vitro transendothelial invasiveness was identified to express increased levels of a new alternative splice variant of decay-accelerating factor (DAF). DAF seems to play an important role in some malignant tumours since on the one hand the expression of complement inhibitors on the surface of tumour cells prevents the accumulation of complement factors and in consequence cell lysis. On the other hand, DAF has been identified as a ligand for the CD97 surface receptor which induces cell migration. Immunofluorescence procedures, Western blot analyses, and cDNA clone sequencing were employed to confirm the expression of DAF restricted to invasive tumour cells. Using a radioactive RNA-in situ hybridisation on freshly frozen tissue microarrays and RT-PCR on native tumour tissue, the expression of alternative spliced DAF mRNA was demonstrated in invasive breast cancer. Due to the fact that it could thereby not be detected in normal mammary tissues, it has to be confirmed in larger studies that the DAF splice variant might be a specific tumour marker for invasive breast cancer.

Transfer of functional prostasomal CD59 of metastatic prostatic cancer cell origin protects cells against complement attack

BACKGROUND

Prostasomes are secretory granules produced, stored, and released, by the glandular epithelial cells of the prostate. They express the glycosylphosphatidylinositol (GPI)-anchored complement regulatory protein CD59, which has been shown to be transferred to spermatozoa and erythrocytes.

METHODS

The CD59 content of prostasomes isolated from seminal fluid and malignant prostate cells (PC-3, DU145, and LNCaP) and the transfer of prostasomal CD59 to rabbit erythrocytes (RE) and to PIPLC-treated and unmanipulated cancer cells were investigated using FACS. All prostasomes were also incubated with RE and tested in a hemolytic assay.

RESULTS

Prostasomes from cancer cells had higher expression of CD59 than those of normal cells. Prostasomal CD59 of different origin could be transferred to RE, malignant cell lines stripped of CD59 by PIPLC, or unmanipulated LNCaP cells. Malignant cell prostasomes had an increased ability to inhibit complement-mediated lysis compared to those from non-malignant cells.

CONCLUSIONS

These results point to a novel mechanism by which prostasomes can protect prostatic malignant cells from complement attack.

Prostaglandin E2 Regulates the Complement Inhibitor CD55/Decay-accelerating Factor in Colorectal Cancer

Cyclooxygenase-derived prostaglandin E(2) (PGE(2)) stimulates tumor progression by modulating several proneoplastic pathways. The mechanisms by which PGE(2) promotes tumor growth and metastasis through stimulation of cell migration, invasion, and angiogenesis have been fairly well characterized. Much less is known, however, about the molecular mechanisms responsible for the immunosuppressive effects of PGE(2). We identified PGE(2) target genes and subsequently studied their biologic role in colorectal cancer cells. The complement regulatory protein decay-accelerating factor (DAF or CD55) was induced following PGE(2) treatment of LS174T colon cancer cells. Analysis of PGE(2)-mediated activation of the DAF promoter employing 5'-deletion luciferase constructs suggests that regulation occurs at the transcriptional level via a cyclic AMP/protein kinase A-dependent pathway. Nonsteroidal anti-inflammatory drugs blocked DAF expression in HCA-7 colon cancer cells, which could be restored by the addition of exogenous PGE(2). Finally, we observed an increase in DAF expression in the intestinal mucosa of Apc(Min+/-) mice treated with PGE(2) in vivo. In summary, these results indicate a novel immunosuppressive role for PGE(2) in the development of colorectal carcinomas.

Complement regulatory proteins in normal human esophagus and esophageal squamous cell carcinoma

BACKGROUND

Altered expression of three complement regulatory proteins, decay-accelerating factor (CD55), membrane cofactor protein (CD46) and homologous restriction factor 20 (CD59) has been identified in human gastrointestinal malignancies, but their expression in esophageal cancer has not been described. Therefore the purpose of the present paper was to study the distribution of these proteins in human normal and malignant esophageal mucosa.

METHODS AND RESULTS

In the normal esophageal mucosa, CD55 predominantly stained on the cell membrane of squamous epithelium in the superficial and prickle cell layers, whereas CD46 most intensely stained on the cell membrane in the basal and parabasal cell layers. In contrast to this reciprocal expression of CD55 and CD46, CD59 was broadly distributed on the cell membrane in all layers. In the esophageal squamous cell carcinoma, CD55 staining was intense in the stroma but was negligible in the cancer cells. In contrast, CD46 and CD59 stained almost uniformly on the tumor cell membrane. There was a significant difference in the intensity of the staining of CD55 and CD46 among cells in various layers of normal esophageal mucosa and esophageal carcinoma cells, but not in the staining of CD59. Similar expression patterns of the three complement regulatory proteins in carcinoma cells and in normal epithelium in the basal and parabasal cell layers were observed.

CONCLUSIONS

These observations on the expression of the three complement regulatory proteins would help understanding of the host immune responses involving the complement system against esophageal squamous cell carcinoma.

Expression of complement regulatory proteins [membrane cofactor protein (CD46), decay accelerating factor (CD55), and protectin (CD59)] in endometrial stressed cells

In the female reproductive tract, the complement system represents a defense mechanism that can act directly against pathogens and cells, and mediates inflammatory response. Endometrial cells are protected from autologous complement attack by membrane-bound complement regulatory proteins (CRPs) that prevent complement activation: membrane cofactor protein (CD46), decay accelerating factor (CD55), and protectin (CD59). In this work we show that all CRPs were overexpressed after LPS exposure. Maximal stimulatory effect was detected after 6h, and was declining after 12h, reaching control levels in 24h. CD59 was the protein showing the more prominent effect. There seems to be a slight increase of CRP expression in the endometrium of sterile patients that have anti-endometrial antibodies (AEA) in their serum. Our results suggest that under stress, the high expression of CRPs (CD46, CD55, and CD59) could protect endometrial injured cells against complement mediated lysis. The survival of these cells with some biochemical modifications would enable autoimmune response.