Cancer and pregnancy share similar mechanisms of immunological escape

Clinical, oral immunological and microbiological shifts during and after pregnancy

OBJECTIVES

Physiological changes and shifts in the oral microbiota composition during pregnancy may affect the maternal immune system. Uncomplicated pregnancy is associated with a T-helper (Th) 2 predominant cytokine regulation (anti-inflammatory), while oral health deterioration during pregnancy is reflected by severe gingival inflammation, a primarily Th1 cytokine phenotype (pro-inflammatory), and oral microbiome alterations. This prospective observational study aimed to evaluate Th cytokine shifts and changes in the oral microbiota composition in saliva of women before and after birth.

MATERIAL AND METHODS

Saliva (n = 96) was collected before and 6 months after birth, and medical, oral health, and periodontal status were assessed. In a multiplex immunoassay, 10 cytokines were simultaneously analyzed and cumulative Th1 and Th2 cytokine levels and Th1/Th2 ratio were calculated for all groups. Putative periodontal pathogens (n = 6) were evaluated by quantitative real-time polymerase chain reaction.

RESULTS

Th2 cytokine levels were significantly lower (p = 0.014) while pro-inflammatory cytokine levels were significantly higher (p < 0.01) during pregnancy than postpartum. Similar Th1 levels were found between the groups (p = 0.143). Th1 and Th2 cytokines positively correlated with periodontal parameters (p < 0.001) and levels of studied bacteria during pregnancy (p < 0.05).

CONCLUSIONS

This study identified a significantly increased Th1/Th2 cytokine ratio during pregnancy and a positive association with putative periodontal pathogens. This immunological and microbiological deregulation in the oral milieu during pregnancy is suggestive of a destructive inflammatory periodontal profile.

STUDY REGISTRATION

Clinical Trials.gov (Record BAP-2015).

CLINICAL RELEVANCE

Understanding altered oral immunological and microbiological regulation patterns during pregnancy may help improve the inflammatory periodontal profile in pregnant women.

The Update Immune-Regulatory Role of Pro- and Anti-Inflammatory Cytokines in Recurrent Pregnancy Losses

Recurrent pregnancy losses (RPL) is a common reproductive disorder with various underlying etiologies. In recent years, rapid progress has been made in exploring the immunological mechanisms for RPL. A propensity toward Th2 over Th1 and regulatory T (Treg) over Th17 immune responses may be advantageous for reproductive success. In women with RPL and animals prone to abortion, an inordinate expression of cytokines associated with implantation and early embryo development is present in the endometrium or decidua secreted from immune and non-immune cells. Hence, an adverse cytokine milieu at the maternal-fetal interface assaults immunological tolerance, leading to fetal rejection. Similar to T cells, NK cells can be categorized based on the characteristics of cytokines they secrete. Decidual NK (dNK) cells of RPL patients exhibited an increased NK1/NK2 ratio (IFN-γ/IL-4 producing NK cell ratios), leading to pro-inflammatory cytokine milieu and increased NK cell cytotoxicity. Genetic polymorphism may be the underlying etiologies for Th1 and Th17 propensity since it alters cytokine production. In addition, various hormones participate in cytokine regulations, including progesterone and estrogen, controlling cytokine balance in favor of the Th2 type. Consequently, the intricate regulation of cytokines and hormones may prevent the RPL of immune etiologies. Local or systemic administration of cytokines or their antagonists might help maintain adequate cytokine milieu, favoring Th2 over Th1 response or Treg over Th17 immune response in women with RPL. Herein, we provided an updated comprehensive review regarding the immune-regulatory role of pro- and anti-inflammatory cytokines in RPL. Understanding the roles of cytokines involved in RPL might significantly advance the early diagnosis, monitoring, and treatment of RPL.

The Possible Role of Interleukin (IL)-18 and Nitrous Oxide and Their Relation to Oxidative Stress in the Development and Progression of Breast Cancer

Background:

Cancer breast is the most common malignant tumor in females globally. Mechanisms linking inflammatory cytokines and tumour growth and progression have not been established. Interleukin (IL)-18 has a modifying role in the immune defense against tumor cells. It induces production of IFN-γ. It also increases the immune cells cytotoxic activity and enhances the production of other proinflammatory cytokine. Nitric oxide (NO) has both promoting and inhibiting effects on tumorigenesis. Oxidative stress is a phenomenon that leads to oxidative damage of biomolecules, mutagenesis and carcinogenesis.

Objective:

The purpose of this research is to identify the potential role of IL18 and NO and their relation to oxidative stress in the development of cancer breast.

Patients and Methods:

This study included 120 women split into two groups ; control group and patient groups that divided into: group B (30 patients with benign breast tumors), group N (30newly diagnosed cancer breast patients) ; and group M (30 metastatic cancer breast patients).

Results:

Serum total anti-oxidant capacity was significant high in both cancer breast groups. Total oxidative capacity was significantly higher level in metastatic group. NO levels were significantly higher values in the three cancer breast patients groups compared to control group.IL18 was significantly high in the metastatic group.

Reflections upon immunological mechanisms involved in fertility, pregnancy and parasite infections

During a pregnancy, the mother accepts her semi-allogeneic fetus with no signs of immunological rejection. Therefore, some modulation of the maternal immune system must occur. Similarly, changes in the host's immune system occurs during infections with parasites. In a study conducted in an endemic area in Bolivia, it has been reported that women infected with either the helminthic parasite roundworm or hookworm were estimated to give birth to either two more, or three fewer, children than uninfected, endemic women, respectively. Immune regulation by helminthic parasites is a rather well-researched concept, but there are few reports on the effects on human fecundity. The current review focuses on mechanisms of possible importance for especially the increased fertility rates in women infected with roundworm. The host immune response to roundworm has been hypothesized to be more favourable for a successful pregnancy because it bears resemblance to the anti-inflammatory immunological responses observed in pregnancy, steering the immunological response away from a pro-inflammatory state that seem to suppress fecundity. Further research into parasitic worm interactions, fertility, and the molecular mechanisms that they unfold may widen our understanding of the immunomodulatory pathways in both helminthic infections and in fertility and pregnancy.

PLAC1: biology and potential application in cancer immunotherapy

The emergence of immunotherapy has revolutionized medical oncology with unprecedented advances in cancer treatment over the past two decades. However, a major obstacle in cancer immunotherapy is identifying appropriate tumor-specific antigens to make targeted therapy achievable with fewer normal cells being impaired. The similarity between placentation and tumor development and growth has inspired many investigators to discover antigens for effective immunotherapy of cancers. Placenta-specific 1 (PLAC1) is one of the recently discovered placental antigens with limited normal tissue expression and fundamental roles in placental function and development. There is a growing body of evidence showing that PLAC1 is frequently activated in a wide variety of cancer types and promotes cancer progression. Based on the restricted expression of PLAC1 in testis, placenta and a wide variety of cancers, we have designated this molecule with new terminology, cancer-testis-placenta (CTP) antigen, a feature that PLAC1 shares with many other cancer testis antigens. Recent reports from our lab provide compelling evidence on the preferential expression of PLAC1 in prostate cancer and its potential utility in prostate cancer immunotherapy. PLAC1 may be regarded as a potential CTP antigen for targeted cancer immunotherapy based on the available data on its promoting function in cancer development and also its expression in cancers of different histological origin. In this review, we will summarize current data on PLAC1 with emphasis on its association with cancer development and immunotherapy.

Highly expressed placental miRNAs control key biological processes in human cancer cell lines

Despite being a healthy tissue, the constituent cells of the placenta, share similar characteristics with tumor cells, such as increased cell growth, migration, and invasion. However, while these processes are stochastic and uncontrolled in cancer cells, in placenta they are precisely controlled. Since miRNAs have been reported to regulate genes that control the molecular mechanisms necessary for the development of both human placenta and cancer, we addressed for miRNAs highly expressed in the placenta that could be involved in tumorigenesis. Here, we assessed the miRNA profile in placenta samples using microarray analysis. The results showed that miR-451 and miR-720, highly expressed placental miRNAs, presented very low or undetectable expression in cancer cell lines compared to the normal placenta and healthy tissues. Additionally, transfection of miR-451 or miR-720 mimics in choriocarcinoma cell line (JEG3) and colorectal adenocarcinoma cell line (HT-29) resulted in impaired cell proliferation, decreased cell migration and invasion and reduced ability of colony formation. These findings provide evidence that placenta may work as an alternative model to identify novel miRNAs involved in pathways controlling tumorigenesis.

Villi-specific Gene Expression Reveals Novel Prognostic Biomarkers in Multiple Human Cancers

Despite many striking connections, the biological similarities between embryonic development and tumorigenesis have not been well explored. Development of the placental villi is a crucial process involving many cellular activities, including immunity, proliferation, and cell adhesion. In this study, we designed a strategy to identify the gene expression pattern of villi development and to explore the corresponding features in tumors. We discovered villi-specific genes that are highly expressed in the villus as opposed to the mature placenta and then measured the expression levels of these genes in tumors. We found large changes in the expression of villi-specific genes in multiple types of cancer. These villi-specific genes showed distinct expression patterns and were primarily involved in three biological processes: immune-related (5), proliferation-related (6), and focal adhesion-related (8); these genes were extracted from the corresponding enriched Gene Ontology (GO) terms. We observed that these genes were also dysregulated at the transcriptional level across several tumor types. Moreover, the expression of these three gene groups was associated with poor prognosis in a subset of tumors. Based on villi-specific gene expression, this correlation study indicated the existence of common gene expression patterns between embryonic development and tumorigenesis. Therefore, a systematic analysis of villi-specific gene aberrations in various tumors could serve as an indicator for identifying novel prognostic biomarkers.

Trophoblast Glycoprotein (TPGB/5T4) in Human Placenta: Expression, Regulation, and Presence in Extracellular Microvesicles and Exosomes

BACKGROUND

Many parallels exist between growth and development of the placenta and that of cancer. One parallel is shared expression of antigens that may have functional importance and may be recognized by the immune system. Here, we characterize expression and regulation of one such antigen, Trophoblast glycoprotein (TPGB; also called 5T4), in the placenta across gestation, in placentas of preeclamptic (PE) pregnancies, and in purified microvesicles and exosomes.

METHODS

Trophoblast glycoprotein expression was analyzed by real-time reverse transcription-polymerase chain reaction (RT-PCR), Western blot, and immunohistochemistry. Regulation of 5T4 in cytotrophoblast cells was examined under either differentiating conditions of epidermal growth factor or under varying oxygen conditions. Microvesicles and exosomes were purified from supernatant of cultured and perfused placentas.

RESULTS

Trophoblast glycoprotein expression was prominent at the microvillus surface of syncytiotrophoblast and on the extravillous trophoblast cells, with minimal expression in undifferentiated cytotrophoblasts and normal tissues. Trophoblast glycoprotein expression was elevated in malignant tumors. In cytotrophoblasts, 5T4 was induced by in vitro differentiation, and its messenger RNA (mRNA) was increased under conditions of low oxygen. PE placentas expressed higher 5T4 mRNA than matched control placentas. Trophoblast glycoprotein was prominent within shed placental microvesicles and exosomes.

CONCLUSION

Given the potential functional and known immunological importance of 5T4 in cancer, these studies reveal a class of proteins that may influence placental development and/or sensitize the maternal immune system. In extravillous trophoblasts, 5T4 may function in epithelial-to-mesenchymal transition during placentation. The role of syncytiotrophoblast 5T4 is unknown, but its abundance in shed syncytial vesicles may signify route of sensitization of the maternal immune system.

Proinflammatory and Anti-Inflammatory Cytokines Mediated by NF-κB Factor as Prognostic Markers in Mammary Tumors

Inflammation results in the production of cytokines, such as interleukin- (IL-) 4 and IL-10 with immunosuppressive properties or IL-6 and TNF-α with procarcinogenic activity. Furthermore, NF-κB is the major link between inflammation and tumorigenesis. This study verified the interaction between active inflammatory cytokines in the tumor microenvironment and serum of female dogs with mammary tumors and their correlation with the clinicopathological characteristics and overall survival. Measurement of gene expression was performed by qPCR and protein levels by ELISA/Luminex. High gene and protein expression levels of NF-κB, IL-6, and TNF-α were found in association with characteristics that reflect worse prognosis and a negative correlation between TNF-α protein expression and survival time was observed (p < 0.05). In contrast, high gene and protein expression levels of IL-4 and IL-10 were associated with characteristics of better prognosis and an increased level of IL-4 and a longer survival time of animals were obtained (p < 0.05). In addition, there was a positive correlation between TNF-α and IL-6 expression in association with NF-κB. The results show a significant correlation of these cytokines with tumor development, associated with NF-κB expression and cytokines promodulation, showing that these biological factors could be used as predictive and prognostic markers in breast cancer.

Multiple Myeloma in Pregnancy--A Review of the Literature and a Case Series

Multiple myeloma (MM) typically affects older patients with a median age at diagnosis of 67 to 70 years and only 3% of cases are diagnosed before the age of 40. Moreover, MM is more common in men. Therefore, pregnancy rarely occurs in patients with MM and only 37 cases of MM in pregnancy have been reported in the literature. Herein we report an additional 5 cases. The diagnosis of MM might be problematic in this context because some of the symptoms and signs, such as back pain and anemia, can be attributed to pregnancy. Furthermore, if the patient wishes to continue her pregnancy, therapeutic options are currently limited. The list of agents that can be safely administered in pregnant women includes glucocorticoids. Moreover, any continuation of pregnancy has obvious long-term psychosocial repercussions for the patient and her family because of the currently incurable nature of MM. The reported cases of MM in pregnancy represent a spectrum of clinical manifestations. The selection of efficacious and safe treatments is challenging, especially if continuation of pregnancy is desired. Although some authors postulate that pregnancy might lead to progression of MM, data are limited and no consensus on this point has been reached.

Decreased Interferon Alpha/Beta Signature Associated with Human Lung Tumorigenesis

Accumulating evidence suggests that interferon (IFN) alpha/beta are involved in antitumor immunity and cancer immunoediting, but information on the antitumor effects of IFN alpha/beta in lung cancer is limited. In our study, we elucidated the IFN alpha/beta signature during both human fetal lung development and lung tumorigenesis. Our findings indicated gradual upregulation in the IFN alpha/beta signature during human fetal lung development. In addition, this signature was progressively downregulated in normal human airway epithelial cells from lung cancer patients, in immortalized human bronchial epithelial cell lines from later passages, in late-stage lung squamous cell carcinoma (LSCC) tissues, and in LSCC tissues exhibiting lymph node metastasis. Therefore, from its earliest stages, lung tumorigenesis may be associated with a decreased IFN alpha/beta signature. This association may provide insight to guide the detection of high-risk lung cancer patients.

Embryos of the zebrafish Danio rerio in studies of non-targeted effects of ionizing radiation

The use of embryos of the zebrafish Danio rerio as an in vivo tumor model for studying non-targeted effects of ionizing radiation was reviewed. The zebrafish embryo is an animal model, which enables convenient studies on non-targeted effects of both high-linear-energy-transfer (LET) and low-LET radiation by making use of both broad-beam and microbeam radiation. Zebrafish is also a convenient embryo model for studying radiobiological effects of ionizing radiation on tumors. The embryonic origin of tumors has been gaining ground in the past decades, and efforts to fight cancer from the perspective of developmental biology are underway. Evidence for the involvement of radiation-induced genomic instability (RIGI) and the radiation-induced bystander effect (RIBE) in zebrafish embryos were subsequently given. The results of RIGI were obtained for the irradiation of all two-cell stage cells, as well as 1.5 hpf zebrafish embryos by microbeam protons and broad-beam alpha particles, respectively. In contrast, the RIBE was observed through the radioadaptive response (RAR), which was developed against a subsequent challenging dose that was applied at 10 hpf when <0.2% and <0.3% of the cells of 5 hpf zebrafish embryos were exposed to a priming dose, which was provided by microbeam protons and broad-beam alpha particles, respectively. Finally, a perspective on the field, the need for future studies and the significance of such studies were discussed.

Tumor associated regulatory dendritic cells

Immune effector and regulatory cells in the tumor microenvironment are key factors in tumor development and progression as the pathogenesis of cancer vitally depends on the multifaceted interactions between various microenvironmental stimuli provided by tumor-associated immune cells. Immune regulatory cells participate in all stages of cancer development from the induction of genomic instability to the maintenance of intratumoral angiogenesis, proliferation and spreading of malignant cells, and formation of premetastatic niches in distal tissues. Dendritic cells in the tumor microenvironment serve as a double-edged sword and, in addition to initiating potent anti-tumor immune responses, may mediate genomic damage, support neovascularization, block anti-tumor immunity and stimulate cancerous cell growth and spreading. Regulatory dendritic cells in cancer may directly and indirectly maintain antigen-specific and non-specific T cell unresponsiveness by controlling T cell polarization, MDSC and Treg differentiation and activity, and affecting specific microenvironmental conditions in premalignant niches. Understanding the mechanisms involved in regulatory dendritic cell polarization and operation and revealing pharmacological means for harnessing these pathways will provide additional opportunities for modifying the tumor microenvironment and improving the efficacy of different therapeutic approaches to cancer.

Expression of nonclassical molecule human leukocyte antigen-G in oral lesions

INTRODUCTION

Human leukocyte antigen (HLA)-G is a nonclassic class I molecule that acts as a modulator of immune responses, and the expression of these molecules in virus-infected cells has been associated with subversion of the immune response.

OBJECTIVE

In this study, we performed a cross-sectional study, systematically comparing the expression of the HLA-G in benign, premalignant, and malignant oral lesions and correlating it with the presence of high-risk and low-risk human papillomavirus (HPV) types. SPECIMENS AND METHODS: Oral biopsies were collected from 51 patients and analyzed by immunohistochemistry using anti-HLA-G antibody. Human papillomavirus detection and typing from oral biopsies were obtained by polymerase chain reaction using GP5+/GP6+ and specific primers.

RESULTS

The 51 biopsies were stratified into 3 groups according to lesion grade: oral benign lesions (oral hyperplasia and papilloma, n = 16), oral premalignant lesions (oral leukoplakia with dysplasia and lichen planus, n = 17), and malignant lesions (oral squamous cell carcinoma, n = 18). Human leukocyte antigen-G overexpression was mainly observed in benign and premalignant oral lesions but was not related to HPV infection (P > .05). On the other hand, HPV DNA was detected in 24 (47%) oral lesions, mainly in benign and premalignant lesions, with the most frequent type detected being high-risk HPV type.

CONCLUSION

The HLA-G molecule was expressed in a significant number of benign oral lesions and was not correlated with HPV infection or oral cancer.

Interleukin 10 and tumor necrosis factor-alpha in pregnancy: aspects of interest in clinical obstetrics

The purpose of this study was to review the literature regarding the action of the cytokines interleukin 10 (IL-10) and tumor necrosis factor-alpha (TNF-α) in pregnancy and to emphasize the factors that are of interest to clinical obstetrics. The literature highlights several actions of IL-10 and TNF-α during pregnancy. The actions of these cytokines seem to be antagonistic and dependent on the balance between them, which is orchestrated by the specific immunosuppressive action of IL-10. TNF-α has a characteristic inflammatory action, and it is an additional diabetogenic factor in pregnancy. The loss of the control of the production of these cytokines, with increase of TNF-α, is related to the risk for developing obstetric complications, particularly recurrent fetal loss, gestational diabetes mellitus, hypertensive syndromes, and fetal growth restriction. However, study results are controversial and are not clearly defined. These issues are attributed to the heterogeneity of the studies, particularly regarding their sample sizes and sources, the evaluation methods, and the multiplicity of factors and conditions that influence cytokine production. These questions are fundamental and should be addressed in future investigations to obtain more consistent results that can be applied to obstetric practice.

HLA-G polymorphisms, genetic susceptibility, and clinical outcome in childhood neuroblastoma

Neuroblastoma is the most common solid tumor in children less than 5 years of age. The early onset of neuroblastoma suggests that genes involved in fetal development and pregnancy may have a putative role in the etiology of neuroblastoma. The human leukocyte antigen subtype G (HLA-G) molecule plays an important role in immune response regulation and appears to regulate immune tolerance during early pregnancy as well as tumor immunosurveillance. Elevated levels of soluble HLA-G (sHLA-G) have been detected in a number of malignancies including serum samples from neuroblastoma and have been reported to be predictive of tumor relapse in neuroblastoma. In light of previous investigations suggesting that single nucleotide polymorphisms in the HLA-G gene may impact on protein expression levels and isoform production, we examined the influence of HLA-G polymorphisms on the susceptibility and clinical outcome of neuroblastoma in 163 neuroblastoma patients and 404 healthy controls. The distribution of HLA-G polymorphisms, alleles, or allelic groups did not differ between children diagnosed with neuroblastoma and healthy controls. Our analyses did not detect an association between common HLA-G polymorphisms and clinical outcome in patients treated for neuroblastoma.

The immunohistochemical analysis of RCAS1, HLA-G, and B7H4-positive macrophages in partial and complete hydatidiform mole in both applied therapeutic surgery and surgery followed by chemotherapy

INTRODUCTION

The suppressive microenvironment developing around the implantating ovum in normal pregnant women may correlate with the development in cancer patients of a suppressive microenvironment of neoplasmatic cells derived from trophoblasts, such as occurs in molar lesions. Macrophages are suitable candidates for mediating not only the balance of the maternal defensive immune responses to external antigens, but also a tolerance to tumor cells. The aim of our study has been to gain information about the expression of RCAS1, B7H4, and HLA-G within the macrophages present in the microenvironment of the molar lesion.

METHODS

We analyzed the immunoreactivity of such antigens as B7H4, RCAS1, and HLA-G on the macrophages present in tissue samples derived from patients on whom curettage was performed after a diagnosis of molar pregnancy. These patients were then divided into two subgroups according to whether or not they required chemotherapy after the surgical procedure.

RESULTS

We observed a statistically significant increase in the RCAS1-positive macrophage infiltration within the microenvironment of the molar lesions in patients with partial hydatidiform mole in comparison with those patients who exhibited complete hydatidiform mole. There were no such differences, however, in the infiltration of HLA-G- and B7H4-positive macrophages between the two groups of patients. Additionally, we showed that RCAS1- and HLA-G-positive macrophages are more distinct in those cases of complete molar pregnancy where chemotherapy was necessary after surgical treatment while no such differences with respect to B7H4-positive macrophages were observed.

CONCLUSION

The immune-suppressive endometrial microenvironment represented by suppressive macrophages may have an influence on the clinical course of hydatidiform mole.

The relationship between early embryo development and tumourigenesis

With the recent substantial progress in developmental biology and cancer biology, the similarities between early embryo development and tumourigenesis, as well as the important interaction between tumours and embryos become better appreciated. In this paper, we review in detail the embryonic origin of tumour, and the similarities between early embryo development and tumourigenesis with respect to cell invasive behaviours, epigenetic regulation, gene expression, protein profiling and other important biological behaviours. Given an improved understanding of the relationship between early embryo development and tumourigenesis, now we have better and broader resources to attack cancer from the perspective of developmental biology and develop next generation of prognostic and therapeutic approaches for this devastating disease.

Longitudinal modulation of immune system cytokine profile during pregnancy

OBJECTIVE

To characterize immune modulation as expressed by cytokine assays at three time-points in human pregnancy.

STUDY DESIGN

This is a prospective, longitudinal study of a broad panel of cytokine expression during singleton pregnancies resulting in an uncomplicated, full-term, live births. Peripheral blood was obtained at 8-14, 18-22, and 28-32 weeks gestation. Six cytokines - IFN-γ, IL-4, TNF-α, IL-1β, IL-6, and IL-10 - were measured in supernatants obtained from whole blood stimulations with PHA or LPS and were compared to unstimulated controls. Samples were processed by Luminex-100 MAP®. We used Generalized Linear Models (GLM) to evaluate cytokine trajectories.

RESULTS

Complete data were obtained for 45 uncomplicated pregnancies. Overall, peripheral blood WBC's demonstrated dampened cytokine responses. However, over the course of pregnancy, we found enhanced counter-regulatory cytokine expression (e.g., shown by increased IL-10).

CONCLUSION

The overall decrease in pro-inflammatory cytokines and increase in counter-regulatory cytokines as uncomplicated pregnancy progresses supports the evolving concepts of immunoregulation for the maintenance of a viable pregnancy.

Overexpression of miR-152 leads to reduced expression of human leukocyte antigen-G and increased natural killer cell mediated cytolysis in JEG-3 cells

OBJECTIVE

The purpose of this study was to gain a further understanding of the relationship between miR-152 and human leukocyte antigen (HLA)-G in human trophoblast cell line (JEG-3).

STUDY DESIGN

The JEG-3 cells were transfected with pre-miR-152. The effect of the overexpressed miR-152 on HLA-G expression, trophoblast invasion, and natural killer (NK) cell-mediated cytolysis were assessed by reverse-transcription polymerase chain reaction (RT-PCR) and Western blot analysis, transwell invasion assay, and NK cell cytotoxicity assay, respectively.

RESULTS

The miR-152 repressed HLA-G expression but exerted no effect on JEG-3 cell invasion, and overexpression of miR-152 led to increased NK cell-mediated cytolysis in JEG-3 cells.

CONCLUSION

The data indicate that miR-152 may function as an immune system enhancer through up-regulating NK cell-mediated cytolysis of host cells.

On a new strategy of preventive oncology

The etiology of cancer is much wider than separately taken causal agent and rests against the most complicated interrelation and mutuality of many external and internal influences. Our researches with use of fluorescing antibodies to AFP, CEA and Ca-19-9 have shown that they are intensively besieged on a surface of cultivated malignant cells. It is the basic mechanism of tolerance and immunological escape, which is similar to pregnancy when "the maximal immunological most favored status" to developing fetus (semiallogenic transplant) is provided. The earliest revealing of first cancer cells, before steady community of cells and tumor angiogenesis were formed, has particular importance in the fight against cancer. The necessity of the specific completion of the weakened antineoplastic resistibility of people from high oncological risk groups is substantiated. The activity in this direction brought forth the design of embryonic anti-tumor modulator (EATM). EATM is composed of a wide pool of fetal proteins and proteoglycans isolated exceptionally from normal embryonic substances.

Selective activation of trophoblast-specific PLAC1 in breast cancer by CCAAT/enhancer-binding protein beta (C/EBPbeta) isoform 2

The trophoblast-specific gene PLAC1 (placenta-specific 1) is ectopically expressed in a wide range of human malignancies, most frequently in breast cancer, and is essentially involved in cancer cell proliferation, migration, and invasion. Here we show that basal activity of the PLAC1 promoter is selectively controlled by ubiquitous transcription factor SP1 and isoform 2 of CCAAT/enhancer-binding protein beta that we found to be selectively expressed in placental tissue and cancer cells. Binding of both factors to their respective elements within the PLAC1 promoter was essential to attain full promoter activity. Estrogen receptor alpha (ERalpha) signaling further augmented transcription and translation of PLAC1 and most likely accounts for the positive correlation between PLAC1 expression levels and the ERalpha status we observed in primary breast cancer specimens. DNA affinity precipitation and chromatin immunoprecipitation assays revealed that transactivation of the PLAC1 promoter by ligand-activated ERalpha is based on a nonclassical pathway independent of estrogen-response elements, by tethering of ERalpha to DNA-bound CCAAT/enhancer-binding protein beta-2, and SP1. Our findings provide first insight into a novel and hitherto unknown regulatory mechanism governing selective activation of trophoblast-specific gene expression in breast cancer.

Human embryo immune escape mechanisms rediscovered by the tumor

Towards the end of the 1990s, the two opposing theories on immunosurveillance and immunostimulation were extensively studied by researchers in an attempt to understand the complex mechanisms that regulate the relation between tumors and the host's immune system. Both theories probably have elements that would help us to comprehend how the host can induce anti-tumor clinical responses through stimulation of the immune system and which could also give us a deeper insight into the mechanisms of tumor immunosuppression. The model that most resembles the behavior of tumor cells in terms of growth, infiltration and suppression of the immune system of the environment in which they live is undoubtedly that of the embryonic cell. The fetus behaves like an allogenic transplant within the mother's body, using every means it has to escape from and defend itself against the mother's immune system. The majority of these mechanisms are the same as those found in tumor cells: antigenic loss, lack of expression of classic HLA-I molecules, production of immunosuppressive cytokines, induction of lack of expression of co-stimulatory molecules in antigen presenting cells, and induction of apoptosis in infiltrating lymphocytes, with activation of a type Th2 regulatory lymphocyte response. A careful and comparative study of key mechanisms capable of triggering tolerance or cytotoxicity in both embryonic and tumor cells could prove immensely valuable in designing new strategies for anti-tumor immunotherapy.

Research progress in correlation between early embryo development and tumorigenesis

With the increased cognition in developmental biology, researchers have discovered the similarity of biological behaviors between early embryo development and tumorigenesis, as well as the important interaction between tumors and embryos. Therefore, it enlightens us to study tumors from the view of developmental biology, which may provide a new clue for tumor therapy. In this article, we review in detail the embryonic origin of tumors, the similarity between early embryo development and tumorigenesis at the level of gene and protein expression, their important biological behaviors, and moreover, the interaction between tumors and embryos from the angle of developmental biology.

Heightened risk of breast cancer following pregnancy: could lasting systemic immune alterations contribute?

The protective effect of having a first full-term pregnancy (FFTP) at a younger age on women's lifetime risk of breast cancer is well known. Less appreciated is the increased risk seen in the years immediately following pregnancy. This adverse effect is more pronounced and more prolonged in women with later age at FFTP. The mechanisms responsible for this increased risk are still poorly understood. In the present paper, we put forward the hypothesis that the marked peripheral immune changes induced by pregnancy may account for these effects. We highlight immune changes that characterize the unique immune state of pregnancy (a combination of cellular immunosuppression and enhanced inflammatory response), note the resemblance of these changes to cancer escape mechanisms, and discuss why such immune changes may be critical for the development of breast cancer following pregnancy. We further support this idea by initial findings from our own laboratory that the age at FFTP is negatively related to natural killer cell cytotoxicity many years later and propose possible models for the kinetics of the immune changes during and following pregnancy. The effect of age at FFTP on the immune function is currently understudied. Its potential relevance to the development of breast cancer stresses the need for further research.