Breast cancer-associated antigen, DF3/MUC1, induces apoptosis of activated human T cells

MUC21: a new target for tumor treatment

MUC21, also known as Epiglycanin, is a high-molecular-weight glycoprotein with transmembrane mucin properties. It consists of a tandem repeat domain, a stem domain, a transmembrane domain and a cytoplasmic tail. MUC21 is expressed is observed in normal tissues in organs like the thymus, testes, lungs, and large intestine. Research has shown that MUC21 is expressed in esophageal squamous cell carcinoma, lung adenocarcinoma, glioblastoma, thyroid cancer, melanoma, and various other malignant tumors in distinctive manner. Additionally, tumor invasion, metastasis, and poor prognosis are linked to it. Some researchers believe that MUC21 has the potential to become a new target in cancer treatment. This review aims to deliver a comprehensive overview of the glycosylation, function, and research progress of MUC21 in multiple types of cancer and infectious diseases.

A scoring model for predicting early recurrence of gastric cancer with normal preoperative tumor markers: A multicenter study

INTRODUCTION

Prognostic factors for postoperative early recurrence (ER) of gastric cancer (GC) in patients with normal or abnormal preoperative tumor markers (pre-TMs) remain unclear.

MATERIALS AND METHODS

2875 consecutive patients with GC who underwent radical gastrectomy (RG) between January 2010 and December 2016 were enrolled and randomly divided into training and internal validation groups. ER was defined as recurrence within two years of gastrectomy. Normal pre-TMs were defined as CEA≤5 ng/mL and CA199 ≤ 37 U/mL. Least absolute shrinkage selection operator (LASSO) Cox regression analysis was used to screen ER predictors. The scoring model was validated using 546 patients from another hospital.

RESULTS

A total of 3421 patients were included. Multivariate Cox analysis showed that pre-TMs was an independent prognostic factor for ER. Survival after ER was equally poor in the normal and abnormal pre-TMs groups (P = 0.160). Based on LASSO Cox regression, the ER of patients with abnormal pre-TMs was only associated with the pT and pN stages; however, in patients with normal pre-TMs, it was also associated with tumor size, perineural invasion, and prognostic nutritional index. Scoring model constructed for patients with normal pre-TMs had better predictive performance than TNM staging (concordance-index:0.826 vs. 0.807, P < 0.001) and good reproducibility in both validation sets. Moreover, through risk stratification, the scoring model could not only identify the risk of ER but also distinguish ER patterns and adjuvant chemotherapy benefit subgroups.

CONCLUSION

pre-TMs is an independent prognostic factor for ER in GC after RG. The established scoring model demonstrates excellent predictive performance and clinical utility.

Mucin Protein of Aedes aegypti Interacts with Dengue Virus 2 and Influences Viral Infection

Dengue, caused by dengue virus (DENV), is the most prevalent vector-borne viral disease, posing a serious health concern to 2.5 billion people worldwide. DENV is primarily transmitted among humans by its mosquito vector Aedes aegypti; hence, the identification of a novel dengue virus receptor in mosquitoes is critical for the development of new anti-mosquito measures. In the current study, we have identified peptides which potentially interact with the surface of the virion particles and facilitate virus infection and movement during their life cycle in the mosquito vector. To identify these candidate proteins, we performed phage-display library screening against domain III of the envelope protein (EDIII), which plays an essential role during host cell receptor binding for viral entry. The mucin protein, which shared sequence similarity with the peptide identified in the screening, was cloned, expressed, and purified for in vitro interaction studies. Using in vitro pulldown and virus overlay protein-binding assay (VOPBA), we confirmed the positive interaction of mucin with purified EDIII and whole virion particles. Finally, blocking of mucin protein with anti-mucin antibodies partially reduced DENV titers in infected mosquitos. Moreover, mucin protein was found to be localized in the midgut of Ae. aegypti. IMPORTANCE Identification of interacting protein partners of DENV in the insect vector Aedes aegypti is crucial for designing vector control-based strategies and for understanding the molecular mechanism DENV uses to modulate the host, gain entry, and survive successfully. Similar proteins can be used in generating transmission-blocking vaccines.

Mucin 21 confers resistance to apoptosis in an O-glycosylation-dependent manner

Highly glycosylated mucins protect epithelial surfaces from external insults and are related to malignant behaviors of carcinoma cells. However, the importance of carbohydrate chains on mucins in the process of cellular protection is not fully understood. Here, we investigated the effect of human mucin-21 (MUC21) expression on the susceptibility to apoptosis. MUC21 transfection into HEK293 cells decreased the number of apoptotic cells in culture media containing etoposide or after ultraviolet light irradiation. We used Chinese hamster ovary (CHO) cell variants to investigate the importance of MUC21 glycosylation in the resistance to apoptosis. When MUC21 was expressed in CHO-K1 cells, it was glycosylated with sialyl T-antigen and the cells showed resistance to etoposide-induced apoptosis. MUC21 transfection into Lec2 cells, a variant of CHO cells lacking sialylation of glycans, revealed that the presence of nonsialylated T-antigen also renders cells resistant to etoposide-induced apoptosis. MUC21 was transfected into ldlD cells and the glycosylation was manipulated by supplementation to the medium. Nonsupplemented cells and cells supplemented with N-acetylgalactosamine showed no resistance to etoposide-induced apoptosis. In contrast, these cells supplemented with N-acetylgalactosamine plus galactose expressed sialyl T-antigen and exhibited resistance to etoposide-induced apoptosis. Finally, galectin-3 knockdown in MUC21 transfectants of HEK293 cells did not significantly affect MUC21-dependent induction of apoptosis resistance. The results suggest that T-antigen with or without sialic acid is essential to the antiapoptotic effect of MUC21.

Mucin 21 (MUC21) is a large glycoprotein that protects squamous epithelia. Glycan changes in mucins occur in cancer cells and are thought to contribute to malignant progression. We report glycoform-dependent antiapoptotic effects of MUC21. Various MUC21 glycoforms were expressed in HEK293 and CHO cells. Apoptosis was induced using etoposide or UV exposure. MUC21 with glycans terminated with galactose/sialic acid inhibited apoptosis; MUC21 with no glycans or N-acetylgalactoseamine did not.

MUC1 is a potential target to overcome trastuzumab resistance in breast cancer therapy

Although resistance is its major obstacle in cancer therapy, trastuzumab is the most successful agent in treating epidermal growth factor receptor 2 positive (HER2 +) breast cancer (BC). Some patients show resistance to trastuzumab, and scientists want to circumvent this problem. This review elaborately discusses possible resistance mechanisms to trastuzumab and introduces mucin 1 (MUC1) as a potential target efficient for overcoming such resistance. MUC1 belongs to the mucin family, playing the oncogenic/mitogenic roles in cancer cells and interacting with several other oncogenic receptors and pathways, such as HER2, β-catenin, NF-κB, and estrogen receptor (ERα). Besides, it has been established that MUC1- Cytoplasmic Domain (MUC1-CD) accelerates the development of resistance to trastuzumab and that silencing MUC1-C proto-oncogene is associated with increased sensitivity of HER2⁺ cells to trastuzumab-induced growth inhibitors. We mention why targeting MUC1 can be useful in overcoming trastuzumab resistance in cancer therapy.

Combination of tumor markers predicts progression and pathological response in patients with locally advanced gastric cancer after neoadjuvant chemotherapy treatment

BACKGROUND

The prognostic values of preoperative tumor markers (TMs) remain elusive in patients with locally advanced gastric cancer (LAGC) after neoadjuvant chemotherapy treatment (NACT). This study aimed to assess and establish a novel scoring system incorporating carcinoembryonic antigen (CEA), carbohydrate antigen 19-9 (CA19-9), carbohydrate antigen 72-4 (CA72-4) to enhance prognostic accuracy for progression-free survival (PFS) and pathological response (pCR).

METHODS

Patients' data were retrospectively analyzed from December 2006 to December 2017 in our center. The cutoff value of TMs was determined using the time-dependent receiver operating test characteristics method. These three TMs were allocated 1 point each for the post neoadjuvant chemotherapy combination of tumor markers (post-NACT CTM) scores. The training group comprised 533 patients, responsible for full analysis, and the validation group comprised 137 patients based on the selection protocol.

RESULTS

Of 533 enrolled patients, 138, 233, 117, and 45 patients scored 0, 1, 2, 3 respectively. The 3-year PFS rate Multivariate analysis revealed that post-NACT CTM score was an independent predictor of PFS (0 vs. 1, HR: 1.34, 95% CI: 0.92-1.96, P = 0.128; 0 vs. 2, HR: 2.03, 95% CI: 1.35-3.05, P = 0.001; 0 vs. 3, HR: 2.98, 95% CI: 1.83-4.86, P < 0.001). The time-dependent area under curve (AUC) revealed a consistent highest level for post-NACT CTM than other three single TMs. Lower post-NACT CTM score significantly correlated with higher pCR rate based on multivariate logistic regression (2/3 vs. 1, OR: 2.77, 95% CI: 0.90-8.53, P = 0.077; 2/3 vs. 0, OR: 4.33, 95% CI: 1.38-13.61, P = 0.012). A nomogram was formed with both internal and external validation.

CONCLUSIONS

The post-NACT CTM score system served as a strong independent predictor for PFS and pCR in LAGC patients who received NACT. Further population-based studies are required to confirm our results.

An ovary-specific mucin is associated with choriogenesis mediated by prostaglandin signaling in Spodoptera exigua

Polytrophic ovarioles of Spodoptera exigua, a lepidopteran insect, begins with the development of oocytes and differentiation of nurse cells followed by vitellogenesis and choriogenesis. Compared with previtellogenic and vitellogenic developments, choriogenesis has not been clearly understood yet in endocrine control. This study investigated the expression and function of a mucin-like structural protein of S. exigua called Se-Mucin1 in choriogenesis. It was highly expressed in ovarioles containing chorionated oocytes. The expression level of Se-Mucin1 was increased during adult stage as early as 18 h after adult emergence, reaching the maximal level at 24 h and later. Interestingly, DNA amount of Se-Mucin1 was increased by almost four folds during early adult stage while other genes (hexokinase and glyceraldehyde-3-phosphate dehydrogenase) not directly associated with chorion formation did not show genomic DNA increase, suggesting specific gene amplification of Se-Mucin1. RNA interference (RNAi) suppressed Se-Mucin1 expression by injecting 1 μg of double-strand RNA to teneral females (<5 h after emergence), which exhibited significantly impaired fecundity and egg hatching rate. Eggs laid by RNAi-treated females were malformed in eggshell structures with loss of mesh-like fibers. Treatment with aspirin, a prostaglandin (PG) biosynthesis inhibitor, suppressed the induction of Se-Mucin1 expression during early adult stage and impaired egg development. An addition of PGE₂ significantly rescued such impairment in Se-Mucin1 expression and subsequent egg development. These results suggest that PGs mediate choriogenesis of S. exigua by activating the expression of chorion-associated genes including Se-Mucin1.

A Mucin-Like Protein Is Essential for Oviposition in Nilaparvata lugens

Mucins play a variety of roles; for example, in vertebrates, mucins lubricate epithelial surfaces and protect tissue from physical and biological damage, however, knowledge of insect mucins is limited. Here, we identified an eggshell-related mucin-like protein, NlESMuc, in the brown planthopper (BPH), Nilaparvata lugens. NlESMuc was specifically expressed in the follicular cells from the egg chambers of the ovarioles. RNA interference (RNAi) was used to perform functional analysis of NlESMuc. Adult female BPH with NlESMuc knockdown had significantly reduced fecundity, including more difficult oviposition, lower egg production, and eggs that could not hatch. Scanning electron microscopy showed that, in NlESMuc knocked-down BPH, the ultrastructure of the eggshells of fully developed oocytes was loose, and the cross-section showed many small droplets of about 0.1-μm diameter. Based on the results, it is concluded that NlESMuc is an eggshell-related protein and essential for normal oviposition. Our findings help to provide new targets for pesticide design and RNAi-based BPH control and will also provide new insights into insect eggshells and insect mucins.

Immunosuppressive Factors: Role in Cancer Development and Progression

The concept of the immunological surveillance against neoplastic cells was initially proposed by Erlich in 1909 and later elaborated by Burnet. This hypothesis states that the normal function of the immune system, in particular the cell-mediated immunity, is to recognize and destroy the transformed and proliferating tumor cells. The role of cell-mediated immunity during the first steps of tumorigenesis remains controversial. However, there is certain evidence about its importance in the progression and dissemination of cancer. The frequent immunosuppressed condition of cancer patients at tumor relapse or recurrence of secondary tumors is a clinical sign supporting this hypothesis, and many studies have demonstrated a defective immune response in patients diagnosed with advanced cancer. Several mechanisms of escape from the immune surveillance have been described, including the immunoselection of tumor antigen-negative variants, the downregulation of MHC class I expression, suppressive T cells, and the elaboration of immunosuppressive cytokines and other factors. Because of the technical difficulty of isolating the very small amounts from culture supernatants or body fluids, only a few of these substances have been characterized and studied with respect to their biological activity: transforming growth factor-β (TGF-β), the protein p15E, interleukin 10 (IL-10), prostaglandin E2 (PGE2), mucins, suppressive E-receptor (SER), immunosuppressive acidic protein (IAP), and adhesion molecules. The possibility of monitoring cancer patients by testing biochemical factors related to cancer growth led to a proposal to measure a number of these factors as tumor markers. Some of them, e.g mucins, enjoy the consensus of the oncologic community, as for some indications they can help the clinician in the management of cancer patients. Except for the class of mucins, the other above-mentioned immunosuppressive factors have not found any clinical application in the laboratory routine because the information deriving from their measurement, although of speculative and scientific interest, has limited clinical value at present. Nevertheless, even if they have no impact on patient management, these substances do have a potential role to play in the study of cancer patients, and should be taken into account when developing new therapeutic strategies.

Organoids with cancer stem cell-like properties secrete exosomes and HSP90 in a 3D nanoenvironment

Ability to form cellular aggregations such as tumorspheres and spheroids have been used as a morphological marker of malignant cancer cells and in particular cancer stem cells (CSC). However, the common definition of the types of cellular aggregation formed by cancer cells has not been available. We examined morphologies of 67 cell lines cultured on three dimensional morphology enhancing NanoCulture Plates (NCP) and classified the types of cellular aggregates that form. Among the 67 cell lines, 49 cell lines formed spheres or spheroids, 8 cell lines formed grape-like aggregation (GLA), 8 cell lines formed other types of aggregation, and 3 cell lines formed monolayer sheets. Seven GLA-forming cell lines were derived from adenocarcinoma among the 8 lines. A neuroendocrine adenocarcinoma cell line PC-3 formed asymmetric GLA with ductal structures on the NCPs and rapidly growing asymmetric tumors that metastasized to lymph nodes in immunocompromised mice. In contrast, another adenocarcinoma cell line DU-145 formed spheroids in vitro and spheroid-like tumors in vivo that did not metastasize to lymph nodes until day 50 after transplantation. Culture in the 3D nanoenvironment and in a defined stem cell medium enabled the neuroendocrine adenocarcinoma cells to form slowly growing large organoids that expressed multiple stem cell markers, neuroendocrine markers, intercellular adhesion molecules, and oncogenes in vitro. In contrast, the more commonly used 2D serum-contained environment reduced intercellular adhesion and induced mesenchymal transition and promoted rapid growth of the cells. In addition, the 3D stemness nanoenvironment promoted secretion of HSP90 and EpCAM-exosomes, a marker of CSC phenotype, from the neuroendocrine organoids. These findings indicate that the NCP-based 3D environment enables cells to form stem cell tumoroids with multipotency and model more accurately the in vivo tumor status at the levels of morphology and gene expression.

Implication of Soluble Forms of Cell Adhesion Molecules in Infectious Disease and Tumor: Insights from Transgenic Animal Models

Cell adhesion molecules (CAMs) are surface ligands, usually glycoproteins, which mediate cell-to-cell adhesion. They play a critical role in maintaining tissue integrity and mediating migration of cells, and some of them also act as viral receptors. It has been known that soluble forms of the viral receptors bind to the surface glycoproteins of the viruses and neutralize them, resulting in inhibition of the viral entry into cells. Nectin-1 is one of important CAMs belonging to immunoglobulin superfamily and herpesvirus entry mediator (HVEM) is a member of the tumor necrosis factor (TNF) receptor family. Both CAMs also act as alphaherpesvirus receptor. Transgenic mice expressing the soluble form of nectin-1 or HVEM showed almost complete resistance against the alphaherpesviruses. As another CAM, sialic acid-binding immunoglobulin-like lectins (Siglecs) that recognize sialic acids are also known as an immunoglobulin superfamily member. Siglecs play an important role in the regulation of immune cell functions in infectious diseases, inflammation, neurodegeneration, autoimmune diseases and cancer. Siglec-9 is one of Siglecs and capsular polysaccharide (CPS) of group B Streptococcus (GBS) binds to Siglec-9 on neutrophils, leading to suppress host immune response and provide a survival advantage to the pathogen. In addition, Siglec-9 also binds to tumor-produced mucins such as MUC1 to lead negative immunomodulation. Transgenic mice expressing the soluble form of Siglec-9 showed significant resistance against GBS infection and remarkable suppression of MUC1 expressing tumor proliferation. This review describes recent developments in the understanding of the potency of soluble forms of CAMs in the transgenic mice and discusses potential therapeutic interventions that may alter the outcomes of certain diseases.

Personalized characterization of diseases using sample-specific networks

A complex disease generally results not from malfunction of individual molecules but from dysfunction of the relevant system or network, which dynamically changes with time and conditions. Thus, estimating a condition-specific network from a single sample is crucial to elucidating the molecular mechanisms of complex diseases at the system level. However, there is currently no effective way to construct such an individual-specific network by expression profiling of a single sample because of the requirement of multiple samples for computing correlations. We developed here with a statistical method, i.e. a sample-specific network (SSN) method, which allows us to construct individual-specific networks based on molecular expressions of a single sample. Using this method, we can characterize various human diseases at a network level. In particular, such SSNs can lead to the identification of individual-specific disease modules as well as driver genes, even without gene sequencing information. Extensive analysis by using the Cancer Genome Atlas data not only demonstrated the effectiveness of the method, but also found new individual-specific driver genes and network patterns for various types of cancer. Biological experiments on drug resistance further validated one important advantage of our method over the traditional methods, i.e. we can even identify such drug resistance genes that actually have no clear differential expression between samples with and without the resistance, due to the additional network information.

Split anergized Natural Killer cells halt inflammation by inducing stem cell differentiation, resistance to NK cell cytotoxicity and prevention of cytokine and chemokine secretion

The mechanism of suppression of NK cytotoxicity in cancer patients is not clearly established. In this paper we provide evidence that anergized NK cells induce differentiation of healthy Dental Pulp Stem Cells (DPSCs) or transformed Oral Squamous Cancer Stem Cells (OSCSCs) resulting in cell growth inhibition, resistance to NK cell-mediated cytotoxicity and prevention of inflammatory mediators secretion. Induction of cytotoxicity resistance in differentiated cells correlated with increased CD54 and MHC class I surface expression and mediated by the combination of IFN-γ and TNF-α since antibodies to both, but not each cytokine alone, was able to inhibit resistance. In contrast, inhibition of cytokine and chemokine release was mediated by IFN-γ since the addition of anti-IFN-γ antibody, and not anti-TNF-α, restored secretion of inflammatory mediators in NK cell cultures with differentiated DPSCs and OSCSCs. There was a gradual and time dependent decrease in MHC class I and CD54 expression which correlated with the restoration of NK cell cytotoxicity, augmentation of cytokine secretion and increased cell growth from days 0–12 post NK removal. Continuous presence of NK cells is required for the maintenance of cell differentiation since the removal of NK cell-mediated function reverses the phenotype and function of differentiated cells to their stem-like cells.

Induction of Split Anergy Conditions Natural Killer Cells to Promote Differentiation of Stem Cells through Cell-Cell Contact and Secreted Factors

In this paper, we provide evidence that anergized NK cells through secreted factors and direct cell–cell contact have the ability to induce differentiation of healthy dental pulp stem cells and stem cell of apical papillae as well as transformed oral squamous cancer stem cell (OSCSC) and Mia-Paca-2, poorly differentiated stem-like pancreatic tumors, resulting in their resistance to NK cell-mediated cytotoxicity. Induction of NK cell resistance and differentiation in the stem cells correlated with the increased expression of CD54, B7H1, and MHC class I, and mediated by the combination of membrane-bound or secreted IFN-γ and TNF-α from the NK cells since antibodies to both cytokines and not each one alone were able to inhibit differentiation or resistance to NK cells. Similarly, antibodies to both TNF-α and IFN-γ were required to prevent NK-mediated inhibition of cell growth, and restored the numbers of the stem cells to the levels obtained when stem cells were cultured in the absence of anergized NK cells. Interestingly, the effect of anti-IFN-γ antibody in the absence of anti-TNF-α antibody was more dominant for the prevention of increase in surface receptor expression since its addition abrogated the increase in CD54, B7H1, and MHC class I surface expression. Antibodies to CD54 or LFA-1 was unable to inhibit differentiation whereas antibodies to MHC class I but not B7H1 increased cytotoxicity of well-differentiated oral squamous carcinoma cells as well as OSCSCs differentiated by the IL-2 + anti-CD16 mAb-treated NK cells whereas it inhibited the cytotoxicity of NK cells against OSCSCs. Thus, NK cells may inhibit the progression of cancer by killing and/or differentiation of cancer stem cells, which severely halt cancer growth, invasion, and metastasis.

Immunotherapy of multiple myeloma: the start of a long and tortuous journey

The field of tumor immunotherapy is still in its infancy. It is becoming clear that the human immune response is the result of highly complex, continuously evolving interactions between cells of the adaptive and innate arms of the immune system, the internal and external environments, and normal and abnormal cells (e.g., myeloma plasma cells). Despite the considerable advances in our knowledge over the past 30 years, we have still only scratched the surface of the immune system's interaction with malignant diseases such as myeloma and to date, this has not translated into significantly better outcomes for patients with this disease. This review will summarize our current knowledge of the fundamental immunology of myeloma, review immunotherapy trials reported to date and discuss whether, in light of the current information, immunotherapy of multiple myeloma is an achievable goal.

The prognostic role of preoperative and (early) postoperatively change in CA15.3 serum levels in a single hospital cohort of primary operable breast cancers

Measuring CA15.3 serum levels in the early breast cancer setting is not recommended by current ASCO guidelines. In this large single center study, we assess the prognostic value of preoperative (n = 3746), postoperative (n = 4049) and change in (n = 3252) CA15.3, also across different breast cancer phenotypes. Preoperative, postoperative and change in CA15.3 were all significant (p = 0.0348, p < 0.0001, p < 0.0001 respectively in multivariate analysis) predictors of distant metastasis free survival. For breast cancer specific survival, only postoperative and change in CA15.3 were significant predictors (p < 0.0001 both). Multivariate prognostic models did not improve by incorporating information on preoperative CA15.3, but did improve when introducing information on postoperative CA15.3 for distant metastasis (p = 0.0365) and on change in CA15.3 for breast cancer specific survival (p = 0.0291). Change in CA15.3 impacts on prognosis (distant metastasis) differently in different breast cancer phenotypes. A decrease in CA15.3 may be informative of improved prognosis in basal like and HER2 like breast cancer.

Dual functions of natural killer cells in selection and differentiation of stem cells; role in regulation of inflammation and regeneration of tissues

Accumulated evidence from our laboratory indicates that conditioned or anergized NK cells have the ability to induce resistance of healthy stem cells and transformed cancer stem cells through both secreted factors and direct cell-cell contact by inducing differentiation. Cytotoxic function of NK cells is suppressed in the tumor microenvironment by a number of distinct effectors and their secreted factors. Furthermore, decreased peripheral blood NK cell function has been documented in many cancer patients. We have previously shown that NK cells mediate significant cytotoxicity against primary oral squamous carcinoma stem cells (OSCSCs) as compared to their more differentiated oral squamous carcinoma cells (OSCCs). In addition, human embryonic stem cells (hESCs), human mesenchymal stem cells (hMSCs), human dental pulp stem cells (hDPSCs) and induced human pluripotent stem cells (hiPSCs) were all significantly more susceptible to NK cell mediated cytotoxicity than their differentiated counterparts or parental cells from which they were derived. We have also reported that inhibition of differentiation or reversion of cells to a less-differentiated phenotype by blocking NFκB or gene deletion of COX2 significantly augmented NK cell function. Furthermore, the induction of resistance of the stem cells to NK cell mediated cytotoxicity and their subsequent differentiation is amplified when either the stem cells or the NK cells were cultured in the presence of monocytes. Therefore, we propose that the two stages of NK cell maturation namely CD16+CD56dimCD69- NK cells are important for the lysis of stem cells or poorly differentiated cells whereas the CD16dim/-CD56dim/+CD69+NK cells are important for differentiation and eventual regeneration of the tissues and the resolution of inflammation, thus functionally serving as regulatory NK cells (NK(reg)). CD16 receptor on the NK cells were found to be the receptor with significant potential to induce NK cell anergy, however, our recent data indicated that NKp46 but not NKp30 or NKp44 were also able to induce significant anergy in NK cells, although the levels were less when compared to CD16 receptor triggering. The concept of split anergy in NK cells and generation of NK(reg) and its contribution to cell differentiation, tissue repair and regeneration and in tumor resistance will be discussed in this review.

Recent advances in developing synthetic carbohydrate-based vaccines for cancer immunotherapies

Cancer cells can often be distinguished from healthy cells by the expression of unique carbohydrate sequences decorating the cell surface as a result of aberrant glycosyltransferase activity occurring within the cell; these unusual carbohydrates can be used as valuable immunological targets in modern vaccine designs to raise carbohydrate-specific antibodies. Many tumor antigens (e.g., GM2, Ley, globo H, sialyl Tn and TF) have been identified to date in a variety of cancers. Unfortunately, carbohydrates alone evoke poor immunogenicity, owing to their lack of ability in inducing T-cell-dependent immune responses. In order to enhance their immunogenicity and promote long-lasting immune responses, carbohydrates are often chemically modified to link to an immunogenic protein or peptide fragment for eliciting T-cell-dependent responses. This review will present a summary of efforts and advancements made to date on creating carbohydrate-based anticancer vaccines, and will include novel approaches to overcoming the poor immunogenicity of carbohydrate-based vaccines.

Potential rescue, survival and differentiation of cancer stem cells and primary non-transformed stem cells by monocyte-induced split anergy in natural killer cells

Cytotoxic function of NK cells is largely suppressed in the tumor microenvironment by a number of distinct effectors and their secreted factors. The aims of this review are to provide a rationale and a potential mechanism for immunosuppression in cancer and to demonstrate the significance of such immunosuppression in cellular differentiation and progression of cancer. We have recently shown that NK cells mediate significant cytotoxicity against primary oral squamous carcinoma stem cells (OSCSCs) as compared to their more differentiated oral squamous carcinoma cells. In addition, human embryonic stem cells, mesenchymal stem cells (hMSCs), dental pulp stem cells (hDPSCs) and induced pluripotent stem cells were all significantly more susceptible to NK-cell-mediated cytotoxicity than their differentiated counterparts or parental cells from which they were derived. We have also reported that inhibition of differentiation or reversion of cells to a less-differentiated phenotype by blocking NFκB significantly augmented NK-cell function. Total population of monocytes and those depleted of CD16+ subsets were able to substantially suppress NK-cell-mediated lysis of OSCSCs, hMSCs and hDPSCs. Overall, our results suggest that stem cells but not their differentiated counterparts are significant targets of the NK-cell cytotoxicity. The concept of split anergy in NK cells and its contribution to cell differentiation, tissue repair and regeneration and in tumor resistance and progression will be discussed in this review.

Tumor induced inactivation of natural killer cell cytotoxic function; implication in growth, expansion and differentiation of cancer stem cells

Accumulated evidence indicates that cytotoxic function of immune effectors is largely suppressed in the tumor microenvironment by a number of distinct effectors and their secreted factors. The aims of this review are to provide a rationale and a potential mechanism for immunosuppression in cancer and to demonstrate the significance of such immunosuppression in cellular differentiation and progression of cancer. To that end, we have recently shown that NK cells mediate significant cytotoxicity against primary oral squamous carcinoma stem cells (OSCSCs) as compared to their more differentiated oral squamous carcinoma cells (OSCCs). In addition, human embryonic stem cells (hESCs), Mesenchymal Stem Cells (hMSCs), dental pulp stem cells (hDPSCs) and induced pluripotent stem cells (hiPSCs) were all significantly more susceptible to NK cell mediated cytotoxicity than their differentiated counterparts or parental cells from which they were derived. We have also reported that inhibition of differentiation or reversion of cells to a less-differentiated phenotype by blocking NFκB or targeted knock down of COX2 in primary monocytes in vivo significantly augmented NK cell function. Total population of monocytes and those depleted of CD16(+) subsets were able to substantially prevent NK cell mediated lysis of OSCSCs, MSCs and DPSCs. Taken together, our results suggest that stem cells are significant targets of the NK cell cytotoxicity. The concept of split anergy in NK cells and its contribution to tissue repair and regeneration and in tumor resistance and progression will be discussed in this review.

Expression of the membrane mucins MUC4 and MUC15, potential markers of malignancy and prognosis, in papillary thyroid carcinoma

BACKGROUND

Papillary thyroid carcinoma (PTC) is the most frequent carcinoma of the thyroid gland and has a relatively good prognosis. However, it is important to identify PTC characteristics that indicate high risk for recurrence and metastasis. To date, overexpression of the membrane mucin, MUC1, has been investigated as a key molecular event in the pathogenesis of aggressive PTC. However, other membrane-associated mucins, matrix metalloproteinase-13 (MMP-13) and tissue inhibitor of metalloproteinase-13 (TIMP-3), have not been studied yet. The aim of this study was to evaluate the expression levels of MUC4, MUC15, MMP-13, and TIMP-3 and their prognostic significance in PTC.

METHODS

We analyzed MUC4, MUC15, MMP-13, and TIMP-3 expression in 10 PTC and 10 normal thyroid tissue samples using real-time reverse transcription-polymerase chain reaction. Tissue array blocks were obtained from 98 PTC cases. Tumor regions and nontumor regions were analyzed in tissue array blocks and immunohistochemistry studies were conducted using sectioned slides. Semiquantitative scores were correlated with clinicopathological factors of 98 PTC patients.

RESULTS

MUC4- and MUC15-specific mRNA was increased by 78-fold and 4.75-fold, respectively, in PTC samples compared with normal thyroid tissues. MMP-13 and TIMP-3 gene expression levels were decreased by approximately 0.39-fold and 0.53-fold, respectively. By immunohistochemistry, MUC4 and MUC15 expression levels were increased in PTC samples compared with normal thyroid tissues (p < 0.001). MMP-13 and TIMP-3 expression levels were decreased in PTC samples compared with normal thyroid tissues (p < 0.001). High MUC4 scores were significantly correlated with small tumor size and papillary thyroid microcarcinoma subtype. High MUC15 scores were significantly correlated with age (≥45 years), distant metastasis, and multifocality.

CONCLUSIONS

MUC4 and MUC15 were overexpressed in PTC, and high MUC15 expression was associated with high malignant potential. MUC15 may serve as a prognostic marker and potential novel therapeutic target in PTC.

Recent advances in mucin immunohistochemistry in salivary gland tumors and head and neck squamous cell carcinoma

This review focuses on the immunohistochemical expression of members of the MUC-type mucin family in salivary gland tumors and head and neck squamous cell carcinomas (HNSCC). Information is available on changes in the expression levels and distribution profiles of MUC1, MUC2, MUC3, MUC4, MUC5AC, MUC5B, MUC6 and MUC7 in tumors of the salivary glands; and of MUC1, MUC2 and MUC4 in HNSCC. In salivary gland tumors the expression patterns of MUC2, MUC3, MUC5AC and MUC6 appear to be very closely correlated with the histopathological tumor type indicating their potential use to improve diagnostic accuracy in salivary gland neoplasia. Some MUC-type mucins have emerged as valuable prognostic indicators in pleomorphic adenoma, mucoepidermoid carcinoma and HNSCC. Nine antibodies directed against different MUC1 antigens have thus far been examined in HNSCC of which monoclonal antibodies DF3, HMFG-1 and Ma695 have shown significant correlations with disease outcome. The importance of taking the specific anti-MUC antibody into consideration when comparing the results of different studies on MUC expression in salivary gland tumors and HNSCC is also highlighted in this review.

Increased lysis of stem cells but not their differentiated cells by natural killer cells; de-differentiation or reprogramming activates NK cells

The aims of this study are to demonstrate the increased lysis of stem cells but not their differentiated counterparts by the NK cells and to determine whether disturbance in cell differentiation is a cause for increased sensitivity to NK cell mediated cytotoxicity. Increased cytotoxicity and augmented secretion of IFN-gamma were both observed when PBMCs or NK cells were co-incubated with primary UCLA oral squamous carcinoma stem cells (UCLA-OSCSCs) when compared to differentiated UCLA oral squamous carcinoma cells (UCLA-OSCCs). In addition, human embryonic stem cells (hESCs) were also lysed greatly by the NK cells. Moreover, NK cells were found to lyse human Mesenchymal Stem Cells (hMSCs), human dental pulp stem cells (hDPSCs) and human induced pluripotent stem cells (hiPSCs) significantly more than their differentiated counterparts or parental lines from which they were derived. It was also found that inhibition of differentiation or reversion of cells to a less-differentiated phenotype by blocking NFkappaB or targeted knock down of COX2 in monocytes significantly augmented NK cell cytotoxicity and secretion of IFN-gamma. Taken together, these results suggest that stem cells are significant targets of the NK cell cytotoxicity. However, to support differentiation of a subset of tumor or healthy untransformed primary stem cells, NK cells may be required to lyse a number of stem cells and/or those which are either defective or incapable of full differentiation in order to lose their cytotoxic function and gain the ability to secrete cytokines (split anergy). Therefore, patients with cancer may benefit from repeated allogeneic NK cell transplantation for specific elimination of cancer stem cells.

Enumeration of blood dendritic cells in patients with multiple myeloma at presentation and through therapy

Multiple myeloma (MM) is a clonal B-cell malignancy characterised by excess bone marrow plasma cells, serum and/or urine paraprotein, immune paraesis, renal failure and lytic bone lesions. Dendritic cells (DC) are key players in the adaptive and innate immune responses, but reside in tissues, so are difficult to quantify in vivo. By enumerating the blood DC pool, we aim to examine the influence of MM disease and accompanying therapy on the DC system. We have shown, using the BDCA DC detection kit, that blood pDC and mDC numbers are suppressed at diagnosis in MM, and uniquely, monoclonal gammopathy of uncertain significance (MGUS) and patients with plasmacytoma. B-cell numbers were also significantly reduced in MM, MGUS and patients with plasmacytoma (p<or=0.005). Standard chemotherapy did not improve the number of mDC1 or pDC seen in the blood of patients with MM. The number of blood mDC1 improved transiently following auto hemopoietic stem cell transplantation, as numbers returned to within the normal range at engraftment and were maintained until D100. The number of blood mDC1 in patients taking thalidomide was also significantly higher than at relapse. These studies suggest that the defects in the B cell and blood DC pool is present in MGUS and plasmacytoma as well as patients with MM and can recover following therapy.

Interaction of current cancer treatments and the immune system: implications for breast cancer therapeutics

Early diagnosis and treatment of breast cancer may account for the current improvement in the mortality of breast cancer. However, achieving a complete 'cure' is the holy grail of cancer medicine and, in many cases, cancer patients still succumb to their ultimate fate. There is therefore a need to devise innovative therapies to overcome this problem. To this end, many emerging therapies utilizing the immune system to eradicate the residues of disease have been described in the preclinical and clinical arenas. However, there is very little work examining the impact of immunotherapy on the existing natural immunity. The relationship between antitumor immunity, in the form of immunotherapy (either passive or active), and current strategies of treatment also needs to be explored. If we are to improve the success of cancer treatment, we must understand how current therapies interact with the immune system and with the emerging immunotherapies. For breast-cancer treatment to be successful, therapeutics should be tailored towards antitumor immunity; they should also avoid tumor-specific tolerance. The sources of information used to prepare this paper were obtained through published work on Pubmed/Medline and materials published on the US/UK governmental agencies' websites.

A polyvalent vaccine for high-risk prostate patients: "are more antigens better?"

We have shown the immunogenicity and safety of synthetic carbohydrate vaccines when conjugated to the carrier keyhole limpet hemocyanin (KLH) and given with the adjuvant, QS-21, in patients with biochemically relapsed prostate cancer. To determine whether immune response could be further enhanced with stimulation by multiple antigens, a hexavalent vaccine was prepared using previously determined doses and administered in a Phase II setting to 30 high-risk patients. The hexavalent vaccine included GM2, Globo H, Lewis(y), glycosylated MUC-1-32mer and Tn and TF in a clustered formation, conjugated to KLH and mixed with QS-21. Eight vaccinations were administered over 13 months. All 30 patients had significant elevations in antibody titers to at least two of the six antigens; 22 patients had increased reactivity with FACS. These serologic responses were lower than that seen previously in patients treated with the respective monovalent vaccines. The reciprocal median combined IgM and IgG antibody titers with ELISA against MUC1, Tn, TF, globo H and GM2 for these 30 patients were 640, 80, 120, 40 and 0, compared to 1280, 640, 1280, 320 and 160 seen in patients receiving individual monovalent vaccines. This hexavalent vaccine of synthetic "self" antigens broke immunologic tolerance against two or more antigens in all 30 vaccinated patients, was safe, but antibody titers against several of the antigens were lower than those seen in individual monovalent trials. No impact on PSA slope was detected. We address the relevance of the multivalent approach for prostate cancer treatment.

Immunodeficiency and immunotherapy in multiple myeloma

Multiple myeloma is a malignant tumour of plasma cells that remains incurable for the vast majority of patients, with a median survival of 2-3 years. It is characterized by the patchy accumulation of tumour cells within bone marrow leading to variable anaemia, bone destruction, hypercalcaemia, renal failure and infections. Immune dysfunction is an important feature of the disease and leads to infections that are both a major cause of morbidity and mortality and may promote tumour growth and resistance to chemotherapy. Numerous defects of the immune system have been described in multiple myeloma although the relative clinical importance of these remains elusive. There has been considerable interest in the identification of an autologous response against myeloma. Although T cells and humoral responses directed against myeloma-associated antigens have been described, it is uncertain if the immune system plays a role in preventing or controlling myeloma cell growth. There is increasing interest in the potential role of immunotherapy but the success of these interventions is likely to be modified by the immunologically hostile environment associated with multiple myeloma. This review attempts to summarize the current knowledge relating to the immune defects found in multiple myeloma.

Antitumor effect of an antibody against gastrointestinal cancer-associated antigen CA19.9

Despite tremendous efforts in developing cancer vaccines and monoclonal antibodies (mAbs), only a few passive or active immunotherapeutic modalities have succeeded. The failure may be due to the existence of immunosuppressive factors, which caused anergy of patients' immune system. In this study, we discovered that CA19.9 is one such immunosuppressive factor, which could inhibit the proliferation of activated human lymphocytes. However, this inhibition could be reversed by a mAb, LC44, which was specifically generated against CA19.9. An in vitro cytotoxic experiment showed that mAb LC44 could form an immunocomplex with CA19.9, which subsequently induced the production of cytotoxic T-cells reacting to CA19.9-positive cancer cells. In addition, mAb LC44 could mediate the complement-dependent cytotoxicity to CA19.9-positive cancer cells. mAb LC44 showed an antitumor effect in immunodeficient mice with colon cancer burden in the presence or absence of CA19.9. Based on the observations from this study, we postulated that the mAb, LC44, could be a promising antitumor agent for gastrointestinal cancer and worthy of further investigation.

Biological and therapeutic significance of MUC1 with sialoglycans in clear cell adenocarcinoma of the ovary

A monoclonal antibody (mAb) MY.1E12 was applied to detect MUC1 with sialylated glycans in a total of 55 formalin-fixed, paraffin-embedded surgical specimens of ovarian clear cell adenocarcinomas. A reverse correlation between the binding levels of this mAb and patient survival was demonstrated. To examine the role of MUC1 in ovarian clear cell carcinomas, two cDNA encoding MUC1 were transfected into ES-2 ovarian clear cell carcinoma cells. By comparing these cells, the role of MUC1 in tumorigenicity, chemosensitivity and survival under anoikis conditions were assessed. The results indicate that MUC1 expressed on ovarian clear cell carcinoma cells is causally involved in the malignant behavior.

Emerging mechanisms of immunosuppression in oral cancers

Mounting effective anti-tumor immune responses against tumors by both the innate and adaptive immune effectors is important for the clearance of tumors. However, accumulated evidence indicates that immune responses that should otherwise suppress or eliminate transformed cells are themselves suppressed by the function of tumor cells in a variety of cancer patients, including those with oral cancers. Signaling abnormalities, spontaneous apoptosis, and reduced proliferation and function of circulating natural killer cells (NK), T-cells, dendritic cells (DC), and tumor-infiltrating lymphocytes (TILs) have been documented previously in oral cancer patients. Several mechanisms have been proposed for the functional deficiencies of tumor-associated immune cells in oral cancer patients. Both soluble factors and contact-mediated immunosuppression by the tumor cells have been implicated in the inhibition of immune cell function and the progression of tumors. More recently, elevated levels and function of key transcription factors in tumor cells, particularly NFkappaB and STAT3, have been shown to mediate immune suppression in the tumor microenvironment. This review will focus on these emerging mechanisms of immunosuppression in oral cancers.

MUC1 induced by Epstein-Barr virus latent membrane protein 1 causes dissociation of the cell-matrix interaction and cellular invasiveness via STAT signaling

Disruption of cellular adhesion is an essential pathobiologic step leading to tumor dissemination. Mucin 1 (MUC1) is a mucinous glycoprotein expressed at the surfaces of epithelial cells in many tissues and their carcinomas. MUC1 plays crucial roles in tumor invasion and metastasis, especially in opposing cell adhesion. We have shown that virus infection, specifically by the human tumor virus Epstein-Barr virus (EBV) induces a spectrum of cellular invasiveness and metastasis factors. Here we show that expression of MUC1 is increased in diverse latently EBV-infected cell lines that express latent membrane protein 1 (LMP1), the main viral oncoprotein, and that the level of MUC1 was suppressed by expression of a dominant-negative mutant of LMP1. Expression of LMP1 in EBV-negative nasopharyngeal cell lines induces expression of MUC1 through activation of the MUC1 promoter via binding of STAT1 and STAT3. Finally, LMP1 reduces cell adhesion ability, which is restored by inhibition of MUC1 expression with MUC1 small interfering RNA (siRNA). In addition, LMP1 increases cell invasiveness, which is suppressed by MUC1 siRNA. Thus, LMP1 induces MUC1, a factor important in an early step of detachment and release of tumor cells, which along with induction of other invasiveness and angiogenic factors may combine to act in a complex sequential process that culminates in metastasis of EBV-infected tumor cells.

Inhibition of nuclear factor kappa B (NFkappaB) activity in oral tumor cells prevents depletion of NK cells and increases their functional activation

The aim of this study is to identify candidate factors which may be responsible for the functional inactivation and depletion of NK cells by tumor cells. Inhibition of NFkappaB activity by an IkappaB super-repressor in HEp2 cells, a cell line commonly used as an oral tumor model, blocked tumor-induced NK cell death, and increased the function of NK cells significantly. Increased expression of CD69 early activation antigen on NK cells as well as augmented proliferation and secretion of IFN-gamma by NK cells were observed when these cells were co-incubated with IkappaB super-repressor transfected HEp2 cells (HEp2-IkappaB((S32AS36A))). More importantly, the secretion of IL-6 was significantly inhibited when NK cells were co-cultured with HEp2-IkappaB((S32AS36A)) cells. In addition, the survival and function of cytotoxic effector cells remained significantly elevated in the presence of IFN-gamma-treated HEp2-IkappaB((S32AS36A)) cells when compared to either untreated or IFN-gamma-treated vector-alone transfected HEp2 cells. Similar findings to those obtained using purified peripheral blood NK cells were also observed when non-fractionated peripheral blood mononuclear cells were used in the co-cultures of immune effectors with HEp2 cell transfectants. Addition of recombinant human IL-6 to the co-cultures of immune effectors with the NFkappaB knockdown HEp2 tumor cells substantially decreased the levels of secreted IFN-gamma. Thus, the results presented in this paper suggest that the inhibition of NFkappaB function in oral tumors may serve to activate and expand the function and numbers of NK cells. Moreover, NFkappaB-mediated increase in IL-6 secretion by oral tumors may in part be responsible for the observed inactivation and death of the immune effectors.

Dendritic cell-based cancer immunotherapy targeting MUC-1

Vaccination therapy using dendritic cells (DC) as antigen presenting cells (APC) has shown significant promise in laboratory and animal studies as a potential treatment for malignant diseases. Pulsing of autologous DCs with tumor-associated antigens (TAA) is a method often used for antigen delivery and choice of suitable antigens plays an important role in designing an effective vaccine. We identified two HLA-A2 binding novel 9-mer peptides of the TAA MUC1, which is overexpressed on various hematological and epithelial malignancies. Cytotoxic T cells generated after pulsing DC with these peptides were able to induce lysis of tumor cells expressing MUC1 in an antigen-specific and HLA-restricted fashion. Within two clinical studies, we demonstrated that vaccination of patients with advanced cancer using DCs pulsed with MUC1 derived peptides is well tolerated without serious side effects and can induce immunological responses. Of 20 patients with metastatic renal cell carcinoma, 6 patients showed regression of metastases with 3 objective responses (1 CR, 2 PR). Furthermore, we found that in patients responding to treatment T cell responses for antigens not used for treatment occurred suggesting that antigen spreading in vivo might be a possible mechanism of mediating antitumor effects. These results demonstrate that immunotherapy in patients with advanced malignancies using autologous DCs pulsed with MUC1 derived peptides can induce immunological and clinical responses. However, further clinical studies are needed to identify the most potent treatment regimen that can consistently mediate an antitumor immune response in vivo.

Strategies of Antigen-Specific T-Cell–Based Immunotherapy for Cancer

The critical role of antigen-specific T-cells in the eradication of cancer has been demonstrated in numerous animal models, while significant challenges need to be conquered before antigen-specific T-cell immunotherapy can achieve true success in clinical practice. These challenges include: (1) weak or nonimmunogenicity of spontaneous tumors, (2) negative immune regulation mechanisms of the host immune system, (3) immune inhibition exerted by tumor cells, (4) physical barrier in solid tumor, and (5) escape or resistance to immune attack by tumor cells. Nonetheless, significant success has been achieved in several clinical trials recently, highlighting the possibility of successful manipulation of the immune system for control and elimination of tumor. We focused our study on summarizing the current knowledge and corresponding strategies for improving autologous cytotoxic T-cell (CTL)-based cancer immunotherapy, which include the following aspects: (1) the selection of tumor antigens for stimulation of CTL, (2) strategies of enhancing maturation and antigen presentation activity of dendritic cells (DC), (3) strategies of activation and maintenance of CTL response, and (4) recruitment of suitable immune effector cells to tumor sites. The successful manipulation of the immune system, based on the more and more detailed knowledge of tumor immunology, may finally reach the goal of "immune surveillance of malignancy."

Immunotherapy in multiple myeloma - possibility or probability?

In a small number of patients with multiple myeloma (MM), long-term disease-free survival has been achieved by harnessing the immune phenomenon, 'graft-versus-tumour' effect, induced by allogeneic haemopoietic stem cell transplantation. This has prompted many investigators to examine ways in which a patient's own immune system can be more effectively directed against their disease, with the ultimate aim of tumour eradication. In this review we assess the current understanding of immunobiology in MM, and how the different components of the immune system, such as dendritic cells, T cells and natural killer cells, may be harnessed using in-vitro and in-vivo priming techniques. We look at the clinical immunotherapy trials reported to date and whether, in light of the current information, immunotherapy for MM is an achievable goal.

An interferon-gamma ELISPOT and immunohistochemical investigation of cytotoxic T lymphocyte-mediated tumour immunity in patients with paraneoplastic cerebellar degeneration and anti-Yo antibodies

Eight patients with paraneoplastic cerebellar degeneration (PCD) and anti-Yo antibodies were investigated to determine whether there is any association between cytotoxic T lymphocyte (CTL) responses reactive with two previously defined Yo-derived, HLA-A2.1 restricted epitopes (cdr2-1 and cdr2-2) and the presence of tumour-infiltrating CD8+ CTLs. cdr2-1 and cdr2-2-specific CTL responses could not be detected in 5 HLA-A2.1(+) patients in an ex vivo interferon-gamma ELISPOT assay and only 2/9 tumour sections contained CD8(+) intratumoural lymphocytes suggesting a very limited role for CTL-mediated tumour immunity in this patient group, all of whom had evidence of widespread malignancy at the time of diagnosis and/or death.

Immunohistochemical evaluation of immune response in invasive ductal breast cancer of not-otherwise-specified type

We investigated endotumoral and peritumoral lymphocytic subsets [natural killer cells (NK), B-cells and cytotoxic/suppressor (CD(8)+) T-cells], and expression of MUC1 and MUC6 glycoprotein with regard to various clinicopathological parameters in invasive breast cancer tissues. The study population consisted of 64 female patients with invasive ductal breast cancer of not-otherwise-specified type. Thirty-five women with benign breast lesions served as controls. High-grade carcinomas exhibited higher numbers of endotumoral NK cells and B-cell aggregates than the rest of the tumors examined (P=0.0003 and 0.027, respectively). Cases with more than three positive lymph nodes and with tumors over 2 cm in diameter exhibited higher numbers of endotumoral NK cells (P=0.047 and 0.023, respectively). Increased numbers of peritumoral CD(8)+ T-cells were detected in cases with lymph node metastases (P=0.045). MUC1 was expressed with weaker staining intensity in the control group than in the group with breast cancer (P=0.011). Grade III carcinomas exhibited significantly stronger expression of MUC6 glycoprotein (P=0.001) than the control group. In conclusion, tumors with markers of poor prognosis exhibited increased numbers of lymphocytic infiltrates, and of NK cells in particular, and stronger MUC1 and MUC6 glycoprotein immunoreactivity than did the other tumors.

Binding of ovarian cancer antigen CA125/MUC16 to mesothelin mediates cell adhesion

Mesothelin is a glycosylphosphatidylinositol-linked cell surface molecule expressed in the mesothelial lining of the body cavities and in many tumor cells. Based on the finding that a soluble form of mesothelin specifically binds to ovarian carcinoma cell line OVCAR-3, we isolated cDNAs encoding a mesothelin-binding protein by expression cloning. The polypeptides encoded by the two cloned cDNA fragments matched to portions of CA125, an ovarian cancer antigen and a giant mucin-like glycoprotein present at the surface of tumor cells. By flow cytometric analysis and immunoprecipitation, we demonstrate that CA125 binds to mesothelin in a specific manner. Binding of CA125 to membrane-bound mesothelin mediates heterotypic cell adhesion as anti-mesothelin antibody blocks binding of OVCAR-3 cells expressing CA125 to an endothelial-like cell line expressing mesothelin. Finally, we show that CA125 and mesothelin are co-expressed in advanced grade ovarian adenocarcinoma. Taken together, our data indicate that mesothelin is a novel CA125-binding protein and that CA125 might contribute to the metastasis of ovarian cancer to the peritoneum by initiating cell attachment to the mesothelial epithelium via binding to mesothelin.

Adoptive T-cell therapy for Epstein-Barr virus-positive Hodgkin's disease

Immunotherapy approaches with antigen-specific cytotoxic T lymphocytes (CTLs) have proved safe and effective prophylaxis and treatment of Epstein-Barr virus (EBV)-associated lymphomas arising after bone marrow transplantation. EBV is also associated with other malignancies including about 40% of cases of Hodgkin's disease making this tumor another potential target for EBV-targeted immunotherapy. While studies with autologous EBV-specific CTLs have shown antiviral activity and immune effects, the clinical responses have been less impressive than those observed in post-transplant lymphomas. There are several possible reasons why the malignant cells in EBV-positive Hodgkin's disease may be less susceptible to immunotherapy approaches, including the fact that they express a more restricted array of EBV-encoded antigens and possess many immune evasion strategies. A number of approaches to overcome these tumor evasion strategies including targeting CTLs to the expressed antigens and genetic modification of CTLs are being evaluated.

The PI 3-kinase-Rac-p38 MAP kinase pathway is involved in the formation of signet-ring cell carcinoma

Signet-ring cell carcinoma is classified in poorly differentiated adenocarcinoma with an aggressive nature and a poor prognosis. We have shown that the activation of PI 3-kinase in highly differentiated adenocarcinomas induces loss of cell-cell contact and formation of vacuoles, giving phenotypes similar to those of signet-ring cell lines. SB203580, a potent p38 MAP kinase inhibitor, blocked this transition, and expression of an active form of MKK6 (MKK6DA), an activator of p38 MAP kinase, gave effects similar to those induced by expression of the active form of PI 3-kinase (BD110), although formation of large vacuoles was not induced. Activation of MKK3, another activator of p38 MAP kinase, was activated in native signet-ring carcinoma cell lines. Anchorage-independent growth of signet-ring cell lines was inhibited by LY294002 or SB203580. These results suggest that p38 MAP kinase is functioning downstream of PI 3-kinase in signaling of the malignant phenotype. Secretion of mucins was enhanced in BD110-expressing cells, but not in MKK6DA-expressing cells, suggesting that secretion of mucins is independent of the MKK6-p38 MAP kinase cascade. Thus, there may be at least two pathways, p38 MAP kinase-dependent and -independent, which are involved in regulation of cell-cell contact and the protein secretion system, respectively.

Differential expression of mucins 1-6 in papillary thyroid carcinoma: evidence for transformation-dependent post-translational modifications of MUC1 in situ

Mucins are primary glycoproteins of epithelia that are known to undergo major changes in their post-translational processing during neoplastic transformation. This study has examined the expression pattern of seven primary mucins, ie mucin (MUC) 1, 2, 3, 4, 5AC, 5B and 6, in normal, hyperplastic, benign neoplastic, and papillary-type carcinoma (PTC) tissues of the thyroid. MUC1 and MUC5B were the only mucins to be widely transcribed in both benign and malignant tissues. In contrast, MUC4 transcripts were undetectable in normal thyroids, and were present in only 40% of the hyperplastic and malignant thyroid tissues. In PTC, MUC1 was identified as a single mRNA transcript, rejecting the idea that this mucin may undergo transformation-dependent alternative splicing in thyroid tumours. The tissue distribution of MUC1 and MUC4 proteins was highly heterogeneous: this largely paralleled their mRNA expression profiles and supported the conclusion that whereas MUC1 was ubiquitously expressed in PTC, MUC4 was detectable in less than 20% of the cases analysed. In order to determine whether post-translational modifications of MUC1, putatively associated with malignancy, also occurred in the mucin produced by PTC, immunohistochemistry was performed with a panel of well-characterized anti-MUC1 antibodies in conjunction with digestion of the tissue sections with deglycosylating enzymes. These experiments, which were supported by immunochemical analyses of the MUC1 and MUC4 glycoforms extracted from tissues, collectively demonstrated markedly divergent MUC1 glycosylation profiles in normal and benign thyroid tissues when compared with PTC. Characteristically, these latter neoplastic cells produced mucin molecules carrying complex poly-N-lactosamine-type glycans capped with fucose and neuraminic acid residues. The present study also found evidence in PTC for the potential presence of proteolytically processed MUC1 isoforms which differ in their post-translational traits depending on whether they are retained on the cell surface or secreted into the extracellular space. It is proposed that the observed differences in the glycosylation properties of normal and neoplastic MUC1 may be exploitable as an ancillary tool in the diagnosis of PTC.

Expression of tumor-associated membrane antigen, RCAS1, in human colorectal carcinomas and possible role in apoptosis of tumor-infiltrating lymphocytes

RCAS1, a novel tumor-associated antigen, is expressed in advanced human neoplasias including uterine and ovarian carcinomas. RCAS1 protein was indicated to induce cell cycle arrest and apoptosis of cultured human lymphoid and myeloid cell lines and normal lymphocytes. In the present study, we investigated the expression and prognostic value of RCAS1 in 58 patients with colorectal carcinomas. RCAS1 protein was detected by immunoperoxidase staining using a mouse monoclonal anti-RCAS1 antibody (22-1-1 antibody). Immunohistochemical examination showed expression of RCAS1 in 75% of colorectal carcinomas with lymph node metastases (n = 24), whereas it was present in only 41% of tumors without metastases (n = 34, P <.05). Patients with RCAS1-positive tumors showed a significantly poorer prognosis than those negative for RCAS1 (P <.05). Multivariate analysis using the Cox regression model indicated that RCAS1 positivity was an independent negative predictor for survival (P =.0300; risk ratio, 0.496). In addition, apoptotic cells of tumor-infiltrating lymphocytes were examined using nonradioactive in situ nick translation in paraffin-embedded sections. The proportion of apoptotic tumor-infiltrating lymphocytes was significantly higher in RCAS1-positive colorectal carcinomas (11.2 +/- 1.0) than in RCAS1-negative tumors (7.9 +/- 1.0, P <.05). Our results suggest that overexpression of RCAS1 may negatively affect the prognosis of human colorectal carcinomas and that RCAS1 may play a role in tumor immune privilege in vivo.

Synergistic stimulation of MUC1 expression in normal breast epithelia and breast cancer cells by interferon-gamma and tumor necrosis factor-alpha

The MUC1 gene encodes a transmembrane mucin glycoprotein that is overexpressed in human breast cancers. Persistent stimulation by proinflammatory cytokines may contribute to increased MUC1 transcription by tumor cells. We demonstrate that MUC1 expression in T47D breast cancer cells and normal human mammary epithelial cells (HMEC) is enhanced by tumor necrosis factor-alpha (TNF-alpha) in the presence of interferon-gamma (IFN-gamma). MUC1 responsiveness to these cytokines was modest in T47D cells and robustly induced in HMEC. Transient transfection of T47D cells with mutant MUC1 promoter constructs revealed that a kappaB site at -589/-580 and the STAT-binding element at -503/-495 and were required for cooperative stimulation by TNFalpha and IFN-gamma. Binding of NFkappaB p65 to the MUC1 kappaB site was induced by TNF-alpha treatment, as demonstrated by electrophoretic mobility shift assay. Specific mutation of the kappaB site prevented binding of NFkappaB p65 and blocked TNF-alpha stimulation of MUC1 promoter activity. Collectively, these studies demonstrate synergistic stimulation of MUC1 expression by TNF-alpha and IFN-gamma that is mediated by independent actions of NFkappaB p65 and STAT1alpha upon kappaB and STAT sites, respectively, in the MUC1 promoter. Strong induction of MUC1 expression by these proinflammatory cytokines is clearly evident in normal mammary epithelium. In contrast, breast tumor cells appear to override normal regulatory responses via as yet undefined cis-elements.

Origin of anti-tumor immunity failure in mammals and new possibility for immunotherapy

There is now much evidence that tumors can be immunogenic. Tumor cells very often express antigens in a form recognizable by the host immune system, but most frequently without consequences on tumor progression. This has been shown in many experimental models and different experimental conditions. Immediate mechanisms for the escape of tumors from immune response are very similar with mechanisms for the escape of fetoplacental unit (as an allograft) from maternal immune response. Similarity between these two mechanisms is so significant that any randomness is banished. Mechanisms of anti-tumor immunity in mammals are substantially different in comparison with mechanisms of anti-tumor immunity in other classes of vertebrates. Moreover, type of most frequently tumors in non-mammalians vertebrates is also significant different. Incidence of malignant tumors in non-mammalians vertebrates is significantly less than incidence of malignant tumors in mammals. These facts indicate that immune system of mammals during anti-tumor immune response is tricked with similarity between tumor cells and trophoblast or other placental cells. It may be a specific evolutionary approach in rendering of anti-tumor immunity failure in mammals, and new possibility for anti-tumor immunotherapy.

Immunotherapy for colorectal cancer

There have been significant improvements in the diagnosis and treatment of colorectal cancer over the past 15 years. However, some 30% of patients with colorectal cancer have disseminated disease at presentation, and furthermore, 50% of patients initially believed to be cured by surgery subsequently relapse and die of the disease. Novel treatment concepts based on understanding the molecular signatures that separate tumor from normal epithelium, such as immunotherapy, are aimed at abolishing microscopic residual disease post standard treatment. The authors provide an overview of progress in the development of specific and nonspecific immunotherapies and explain why definition of end-points and early translation of immunotherapy into the adjuvant field are key to effective use of such agents in the clinical setting.