Caspase activity is downregulated in choriocarcinoma: a cDNA array differential expression study

50 years on and still very much alive: 'Apoptosis: a basic biological phenomenon with wide-ranging implications in tissue kinetics'

Cell death is part of the lifecycle of every multicellular organism. Nineteenth-century pathologists already recognised that organised forms of cell death must exist to explain the demise and turnover of cells during metamorphosis (of insects), embryogenesis and normal tissue homoeostasis [1]. Nevertheless, Kerr, Wyllie and Currie in their seminal paper of 1972, were the first to collate and define the distinct morphological features of controlled cell death in different contexts [2]. To describe the processes of cell deletion observed under both physiological and pathological conditions, they coined the term 'Apoptosis' (derived from the Greek word 'ἀπόπτωσις', meaning 'dropping off or falling off' of petals from flowers). Kerr, Wyllie and Currie defined apoptosis as a mechanism 'complementary to mitosis in the regulation of animal cell populations'. In addition, they already recognised the potential to use this programmed form of cell death for cancer therapy, but they also emphasised the occurrence of apoptosis during cancer development. In this article, some 50 years after its initial publication in The British Journal of Cancer, we revaluate and put the authors initial assumptions and general concepts about apoptosis into the context of modern-day biology.

Distinct microRNA profiles for complete hydatidiform moles at risk of malignant progression

BACKGROUND

MicroRNAs are small noncoding RNAs with important regulatory functions. Although well-studied in cancer, little is known about the role of microRNAs in premalignant disease. Complete hydatidiform moles are benign forms of gestational trophoblastic disease that progress to gestational trophoblastic neoplasia in up to 20% of cases; however, there is no well-established biomarker that can predict the development of gestational trophoblastic neoplasia.

OBJECTIVE

This study aimed to investigate possible differences in microRNA expression between complete moles progressing to gestational trophoblastic neoplasia and those regressing after surgical evacuation.

STUDY DESIGN

Total RNA was extracted from fresh frozen tissues from 39 complete moles collected at the time of uterine evacuation in Brazil. In the study, 39 cases achieved human chorionic gonadotropin normalization without further therapy, and 9 cases developed gestational trophoblastic neoplasia requiring chemotherapy. Total RNA was also extracted from 2 choriocarcinoma cell lines, JEG-3 and JAR, and an immortalized normal placenta cell line, 3A-subE. MicroRNA expression in all samples was quantified using microRNA sequencing. Hits from the sequencing data were validated using a quantitative probe-based assay. Significantly altered microRNAs were then subjected to target prediction and gene ontology analyses to search for alterations in key signaling pathways. Expression of potential microRNA targets was assessed by quantitative real-time polymerase chain reaction and western blot. Finally, potential prognostic protein biomarkers were validated in an independent set of formalin-fixed paraffin-embedded patient samples from the United States (15 complete moles progressing to gestational trophoblastic neoplasia and 12 that spontaneously regressed) using quantitative immunohistochemistry.

RESULTS

In total, 462 microRNAs were identified in all samples at a threshold of <1 tag per million. MicroRNA sequencing revealed a distinct set of microRNAs associated with gestational trophoblastic neoplasia. Gene ontology analysis of the most altered transcripts showed that the leading pathway was related to response to ischemia (P<.001). Here, 2 of the top 3 most significantly altered microRNAs were mir-181b-5p (1.65-fold; adjusted P=.014) and mir-181d-5p (1.85-fold; adjusted P=.014), both of which have been shown to regulate expression of BCL2. By quantitative real-time polymerase chain reaction, BCL2 messenger RNA expression was significantly lower in the complete moles progressing to gestational trophoblastic neoplasia than the regressing complete moles (-4.69-fold; P=.018). Reduced expression of BCL2 was confirmed in tissue samples by western blot. Immunohistochemistry in the independent patient samples revealed significantly lower cytoplasmic expression of BCL2 in the villous trophoblasts from cases destined for progression to gestational trophoblastic neoplasia compared with those that regressed, both with respect to staining intensity (optic density 0.110±0.102 vs 0.212±0.036; P<.001) and to the percentage of positive cells (16%±28% vs 49.4%±28.05%; P=.003).

CONCLUSION

Complete moles progressing to gestational trophoblastic neoplasia are associated with a distinct microRNA profile. miR-181 family members and BCL2 may be prognostic biomarkers for predicting gestational trophoblastic neoplasia risk.

Chitopentaose inhibits hepatocellular carcinoma by inducing mitochondrial mediated apoptosis and suppressing protective autophagy

Hepatocellular carcinoma (HCC) is one of the most prevalent and deadliest cancers. In this study, the anti-tumor effect of singular degree of polymerization (DP) chitooligosaccharides (COS) (DP 2-5) and the underlay molecular mechanisms were investigated on HCC cell line HepG2. MTT assay showed that (GlcN)5 have the best anti-proliferation effect among the different DP of COS (DP2-5). Furthermore, the administration of (GlcN)5 could decrease mitochondrial membrane potential, release cytochrome c into cytoplasm, activate the cleavage of Caspases9/3, thus inducing mitochondrial-mediated apoptosis in HepG2 cells (accounting for 24.57 ± 2.25%). In addition, (GlcN)5 treatment could increase the accumulation of autophagosomes. Further investigation showed that (GlcN)5 suppressed protective autophagy at the fusion of autophagosomes and lysosomes. Moreover, the inhibition of protective autophagy flux by (GlcN)5 could further decrease cell viability and increase the apoptosis rate. Our findings suggested that (GlcN)5 suppressed HepG2 proliferation through inducing apoptosis via the intrinsic pathway and impairing cell-protective autophagy. COS might have the potential to be an agent for lowering the risk of HCC.

Anti-cancer effects of cinnamon: Insights into its apoptosis effects

Cancer is known as a leading cause of death worldwide. In the last two decades, the incidence of cancer has been dramatically increased mostly due to lifestyle changes. The importance of this issue has attracted further attention to discover novel therapies to prevent and treat cancers. According to previous studies, drugs used to treat cancer have shown significant limitations. Therefore, the role of herbal medicines alone or in combination with chemotherapy drugs has been extensively studied in cancer treatment. Cinnamon is a natural component showing a wide range of pharmacological functions including anti-oxidant, anti-microbial and anti-cancer activities. Impaired apoptosis plays critical roles in the initiation and progression of cancer. Increasing evidence indicates that cinnamon, as a therapeutic agent, has anti-cancer effects via affecting numerous apoptosis-related pathways in cancer cells. Here, we highlighted anticancer properties of cinnamon, particularly through targeting apoptosis-related mechanisms.

Insights into dovetailing GTD and Cancers

Gestational trophoblastic diseases (GTD) encompass a group of placental tumors which mostly arise due to certain fertilization defects, resulting in the over-proliferation of trophoblasts. The major characteristic of this diseased state is that β-hCG rises up manifold than that is observed during pregnancy. The incidence of GTD when analyzed on a global scale, figures out that there is a greater risk in South-East Asia, the reason of which remains unclear. An insight into any possible correlation of GTD incidence with cancers, other than choriocarcinoma, is being attempted here. Also, we review the recent developments in research on the molecular etiopathology of GTD. This review would render a wider eye towards a new paradigm of thoughts to connect GTD and breast cancer, which has not been into the picture till date.

Apoptotic index for prediction of postmolar gestational trophoblastic neoplasia

BACKGROUND

Although 85% of patients with a complete hydatidiform mole achieve spontaneous remission after a few months, 15% of them will experience gestational trophoblastic neoplasia, which requires chemotherapy. To date, there is no biomarker to predict post-molar gestational trophoblastic neoplasia before the initiation of human chorionic gonadotropin surveillance.

OBJECTIVE

The purpose of this study was to assess the relationship between the expression of apoptosis markers in the molar villous trophoblasts and the subsequent development of gestational trophoblastic neoplasia after the evacuation of a complete hydatidiform mole.

STUDY DESIGN

This was a retrospective cohort study of patients with complete hydatidiform mole who were diagnosed, treated, and followed at the Center of Trophoblastic Diseases (Botucatu/São Paulo State and Rio de Janeiro/Rio de Janeiro State, Brazil) from 1995-2014. Patients were divided temporally into derivation (1995-2004) and validation (2005-2014) cohorts. Immunohistochemistry was used to examine tissue expression of the apoptosis inhibitor survivin or the pro-apoptotic enzyme caspase-3. Survivin stains for cytoplasmic and nuclear expression were evaluated independently. Caspase-3 expression was measured as an apoptotic index of positive staining cells over negative staining cells multiplied by 100. Receiver operating characteristic curves were then constructed, and the area under the curve was calculated to test the performance characteristics of the staining to predict the subsequent development of gestational trophoblastic neoplasia.

RESULTS

The final study population comprised 780 patients, with 390 patients in each temporal cohort: 590 patients entered spontaneous remission, and 190 patients experienced post-molar gestational trophoblastic neoplasia. Neither nuclear nor cytoplasmic survivin expression performed well as a predictor of subsequent gestational trophoblastic neoplasia. The caspase-3 apoptotic index was a strong risk factor for subsequent gestational trophoblastic neoplasia development. When the apoptotic index was <4%, the risk of gestational trophoblastic neoplasia had an odds ratio of 35.55 (95% confidence interval, 14.02-90.14; P < .0001) in the derivation cohort and an odds ratio of 25.71 (95% confidence interval, 10.13-65.29; P < .0001) in the validation cohort. However, in both cohorts, the positive predictive value for gestational trophoblastic neoplasia of an apoptotic index <4.0% was modest (49% in the derivation cohort and 41% in the validation cohort); the negative predictive value for gestational trophoblastic neoplasia of an apoptotic index ≥4.0% was high (97% in both cohorts).

CONCLUSION

The subsequent development of gestational trophoblastic neoplasia after evacuation of complete hydatidiform mole is tied closely to the apoptotic index, which may be a useful biomarker for future prospective studies.

The Modulation of Apoptotic Pathways by Gammaherpesviruses

Apoptosis or programmed cell death is a tightly regulated process fundamental for cellular development and elimination of damaged or infected cells during the maintenance of cellular homeostasis. It is also an important cellular defense mechanism against viral invasion. In many instances, abnormal regulation of apoptosis has been associated with a number of diseases, including cancer development. Following infection of host cells, persistent and oncogenic viruses such as the members of the Gammaherpesvirus family employ a number of different mechanisms to avoid the host cell’s “burglar” alarm and to alter the extrinsic and intrinsic apoptotic pathways by either deregulating the expressions of cellular signaling genes or by encoding the viral homologs of cellular genes. In this review, we summarize the recent findings on how gammaherpesviruses inhibit cellular apoptosis via virus-encoded proteins by mediating modification of numerous signal transduction pathways. We also list the key viral anti-apoptotic proteins that could be exploited as effective targets for novel antiviral therapies in order to stimulate apoptosis in different types of cancer cells.

Molecular mechanisms of apoptosis and roles in cancer development and treatment

Programmed cell death (PCD) or apoptosis is a mechanism which is crucial for all multicellular organisms to control cell proliferation and maintain tissue homeostasis as well as eliminate harmful or unnecessary cells from an organism. Defects in the physiological mechanisms of apoptosis may contribute to different human diseases like cancer. Identification of the mechanisms of apoptosis and its effector proteins as well as the genes responsible for apoptosis has provided a new opportunity to discover and develop novel agents that can increase the sensitivity of cancer cells to undergo apoptosis or reset their apoptotic threshold. These novel targeted therapies include those targeting anti-apoptotic Bcl-2 family members, p53, the extrinsic pathway, FLICE-inhibitory protein (c-FLIP), inhibitor of apoptosis (IAP) proteins, and the caspases. In recent years a number of these novel agents have been assessed in preclinical and clinical trials. In this review, we introduce some of the key regulatory molecules that control the apoptotic pathways, extrinsic and intrinsic death receptors, discuss how defects in apoptotic pathways contribute to cancer, and list several agents being developed to target apoptosis.

Caspase expression in placental terminal villi in spontaneous and induced pregnancy

Placental levels of caspase 1, 8, and 10 were studied by the immunohistochemical method in full-term spontaneous and induced pregnancies. The levels of these caspases in the placental terminal villi were significantly higher in induced pregnancy. The changes were more marked after intracytoplasmatic injection of spermatozoa.

Downregulation of caspase-10 predicting poor survival after resection of stage II colorectal cancer

PURPOSE

The aim of this study was to evaluate the prevalence and clinical significance of caspase-10 mRNA expression in stage II colorectal cancer.

METHODS

Quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR) was used to analyze caspase-10 expression in cancer tissue and corresponding normal mucosa from 120 patients with stage II colorectal cancer. Variables were analyzed by Chi-square test or Fisher's exact test. Survival was evaluated with method of Kaplan-Meier. Multivariate analysis was performed with Cox's proportional hazards model.

RESULTS

The expression of caspase-10 mRNA was found to be downregulated in cancer tissue compared to normal mucosa (P = 0.001). Poorly differentiated cancer showed lower mRNA expression than cancer with greater differentiation (P = 0.031). Univariate survival curves, estimated using the method of Kaplan-Meier, defined a significant association between caspase-10 expression and both overall survival (P = 0.012) and disease-free survival (P = 0.021). A multivariate analysis, performed by Cox's proportional hazards regression model, confirmed that a low caspase-10 expression was the only significant factor to predict poor prognosis in patients with stage II colorectal cancer.

CONCLUSION

Our data indicate that caspase-10 expression, measured by quantitative real-time RT-PCR, is a possible prognostic factor in patients with stage II colorectal cancer.

Apoptosis in cancer: from pathogenesis to treatment

Apoptosis is an ordered and orchestrated cellular process that occurs in physiological and pathological conditions. It is also one of the most studied topics among cell biologists. An understanding of the underlying mechanism of apoptosis is important as it plays a pivotal role in the pathogenesis of many diseases. In some, the problem is due to too much apoptosis, such as in the case of degenerative diseases while in others, too little apoptosis is the culprit. Cancer is one of the scenarios where too little apoptosis occurs, resulting in malignant cells that will not die. The mechanism of apoptosis is complex and involves many pathways. Defects can occur at any point along these pathways, leading to malignant transformation of the affected cells, tumour metastasis and resistance to anticancer drugs. Despite being the cause of problem, apoptosis plays an important role in the treatment of cancer as it is a popular target of many treatment strategies. The abundance of literature suggests that targeting apoptosis in cancer is feasible. However, many troubling questions arise with the use of new drugs or treatment strategies that are designed to enhance apoptosis and critical tests must be passed before they can be used safely in human subjects.

Downregulation of ASPP1 in gestational trophoblastic disease: correlation with hypermethylation, apoptotic activity and clinical outcome

Gestational trophoblastic disease encompasses a spectrum of trophoblastic lesions including true neoplasms such as choriocarcinomas and the potentially malignant hydatidiform moles, which may develop persistent disease requiring chemotherapy. ASPP1, a member of apoptosis-stimulating proteins of p53 (ASPPs), is a proapoptotic protein that can stimulate apoptosis through its interaction with p53. We evaluated the promoter methylation and expression profiles of ASPP1 in different trophoblastic tissues and its in vitro functional effect on two choriocarcinoma cell lines, namely JEG-3 and JAR. Significant downregulation of ASPP1 mRNA and protein levels was demonstrated in hydatidiform moles and choriocarcinomas, when compared with normal placentas by quantitative-PCR and immunohistochemistry. The ASPP1 mRNA level was significantly correlated with its hypermethylation status, evaluated with methylation-specific PCR, in placenta and gestational trophoblastic disease samples (P=0.024). Moreover, lower ASPP1 immunoreactivity was shown in hydatidiform moles that progressed to persistent gestational trophoblastic neoplasms than in those that regressed (P=0.045). A significant correlation was also found between expression of ASPP1 and proliferative indices (assessed by Ki67 and MCM7), apoptotic activity (M30 CytoDeath antibody), p53 and caspase-8 immunoreactivities. An in vitro study showed that ectopic expression of ASPP1 could trigger apoptosis through intrinsic and extrinsic pathways as indicated by an increase in cleaved caspase-9 and Fas ligand protein expression. The latter suggests a hitherto unreported novel link between ASPP1 and the extrinsic pathway of apoptosis. Our findings suggest that downregulation of ASPP1 by hypermethylation may be involved in the pathogenesis and progress of gestational trophoblastic disease, probably through its effect on apoptosis.

Genetics of gestational trophoblastic neoplasia: an update for the clinician

Gestational trophoblastic disease is a spectrum of disorders ranging from premalignant hydatidiform moles through to malignant invasive moles, choriocarcinoma and rare placental site trophoblastic tumor. The latter are often collectively referred to as gestational trophoblastic tumors or neoplasia (GTN). Although most women can expect to be cured of their disease, many interesting questions arise in the management of gestational trophoblastic disease. Current issues pertain to diagnosis of GTN, predicting progression from hydatidiform moles to GTN and the emergence of drug resistance in GTN. Our understanding of the genetics of GTN has helped us answer some of these questions but many remain unresolved. This article seeks to address recent advances in the genetics of GTN in relation to diagnosis, etiology, prognosis and treatment.

Trophoblast fusion

The villous trophoblast of the human placenta is the epithelial cover of the fetal chorionic villi floating in maternal blood. This epithelial cover is organized in two distinct layers, the multinucleated syncytiotrophoblast directly facing maternal blood and a second layer of mononucleated cytotrophoblasts. During pregnancy single cytotrophoblasts continuously fuse with the overlying syncytiotrophoblast to preserve this end-differentiated layer until delivery. Syncytial fusion continuously supplies the syncytiotrophoblast with compounds of fusing cytotrophoblasts such as proteins, nucleic acids and lipids as well as organelles. At the same time the input of cytotrophoblastic components is counterbalanced by a continuous release of apoptotic material from the syncytiotrophoblast into maternal blood. Fusion is an essential step in maintaining the syncytiotrophoblast. Trophoblast fusion was shown to be dependant on and regulated by multiple factors such as fusion proteins, proteases and cytoskeletal proteins as well as cytokines, hormones and transcription factors. In this chapter we focus on factors that may be involved in the fusion process of trophoblast directly or that may prepare the cytotrophoblast to fuse.

Functional comparison of innate immune signaling pathways in primates

Humans respond differently than other primates to a large number of infections. Differences in susceptibility to infectious agents between humans and other primates are probably due to inter-species differences in immune response to infection. Consistent with that notion, genes involved in immunity-related processes are strongly enriched among recent targets of positive selection in primates, suggesting that immune responses evolve rapidly, yet providing only indirect evidence for possible inter-species functional differences. To directly compare immune responses among primates, we stimulated primary monocytes from humans, chimpanzees, and rhesus macaques with lipopolysaccharide (LPS) and studied the ensuing time-course regulatory responses. We find that, while the universal Toll-like receptor response is mostly conserved across primates, the regulatory response associated with viral infections is often lineage-specific, probably reflecting rapid host–virus mutual adaptation cycles. Additionally, human-specific immune responses are enriched for genes involved in apoptosis, as well as for genes associated with cancer and with susceptibility to infectious diseases or immune-related disorders. Finally, we find that chimpanzee-specific immune signaling pathways are enriched for HIV–interacting genes. Put together, our observations lend strong support to the notion that lineage-specific immune responses may help explain known inter-species differences in susceptibility to infectious diseases.

We know of a large number of diseases or medical conditions that affect humans more severely than non-human primates, such as AIDS, malaria, hepatitis B, and cancer. These differences likely arise from different immune responses to infection among species. However, due to the lack of comparative functional data across species, it remains unclear how the immune system of humans and other primates differ. In this work, we present the first genome-wide characterization of functional differences in innate immune responses between humans and our closest evolutionary relatives. Our results indicate that “core” immune responses, those that are critical to fight any invading pathogen, are the most conserved across primates and that much of the divergence in immune responses is observed in genes that are involved in response to specific microbial and viral agents. In addition, we show that human-specific immune responses are enriched for genes involved in apoptosis and cancer biology, as well as with genes previously associated with susceptibility to infectious diseases or immune-related disorders. Finally, we find that chimpanzee-specific immune signaling pathways are enriched for HIV–interacting genes. Our observations may therefore help explain known inter-species differences in susceptibility to infectious diseases.

The paradox of caspase 8 in human villous trophoblast fusion

Differentiation and subsequent fusion of villous cytotrophoblasts with the overlying syncytiotrophoblast is an essential process for growth and maintenance of the villous trophoblast layer in the human placenta. The understanding of intrinsic mechanisms behind this process is in its infancy, while the list of suggested factors, involved in intercellular fusion of trophoblasts, rapidly increased in the recent past and promises progress on this issue. The early stages of the apoptosis cascade, in particular caspase 8, was suggested to trigger differentiation of cytotrophoblasts, priming them for upcoming fusion. This may sound paradoxical, especially for those who still associate caspase activity with apoptosis only. Here, we summarize data on caspase 8 in the villous trophoblast layer, with a specific focus on localization of pro- and active forms, the sites of its activation and deactivation, and its role and regulation during fusion. Moreover, we revisit the knowledge on fusogens in the villous trophoblast, compare in vitro models for trophoblast fusion and discuss methods to quantify fusion.

Trophoblastic neoplasms express fatty acid synthase, which may be a therapeutic target via its inhibitor C93

Fatty acid synthase (FASN) is an emerging tumor-associated marker and a promising antitumor therapeutic target. In this study, we analyzed the expression of FASN in normal and molar placentas, as well as gestational trophoblastic neoplasia, and assessed the effects of a new FASN inhibitor, C93, on cellular proliferation and apoptosis in choriocarcinoma cells. Using a FASN-specific monoclonal antibody, we found that FASN immunoreactivity was detected in the cytotrophoblast and intermediate (extravillous) trophoblast of normal and molar placentas, as well as in placental site nodules. All choriocarcinomas (n = 33), 90% of epithelioid trophoblastic tumors (n = 20), and 60% of placental site trophoblastic tumors (n = 10) exhibited FASN positivity. FASN expression was further confirmed in vitro by Western blot and real-time PCR. Treatment of JEG3 and JAR cells with C93 induced significant apoptosis through the caspase-3/caspase-9/poly(ADP)ribose polymerase pathway. Cell cycle progression was not affected by the inhibitor. In summary, the data indicate that FASN is expressed in the majority of gestational trophoblastic neoplasias, and is essential for choriocarcinoma cells to survive and escape from apoptosis. FASN inhibitors such as C93 warrant further investigation as targeted therapeutic agents for metastatic and chemoresistant gestational trophoblastic neoplasia.

Pathogenesis of choriocarcinoma: clinical, genetic and stem cell perspectives

Choriocarcinoma is a unique malignant neoplasm composed of mononuclear cytotrophoblasts and multinucleated syncytiotrophoblasts that produce human chorionic gonadotrophin. Choriocarcinoma can occur after a pregnancy, as a component of germ cell tumors, or in association with a poorly differentiated somatic carcinoma, each with distinct clinical features. Cytogenetic and molecular studies, predominantly on gestational choriocarcinoma, revealed the impact of oncogenes, tumor suppressor genes and imprinting genes on its pathogenesis. The role of stem cells in various types of choriocarcinoma has been studied recently. This review will discuss how such knowledge can enhance our understanding of the pathogenesis of choriocarcinoma, enable exploration of novel anti-choriocarcinoma targeted therapy and possibly improve our insight on embryological and placental development.

Genomic biomarkers of pulmonary exposure to tobacco smoke components

BACKGROUND

Associations between smoking and the development of tobacco-related diseases in humans have historically been assessed by epidemiological studies. These studies are further complicated by the number of chemicals used in tobacco and individual smoking habits. An alternative approach is required to assess the biological responses.

OBJECTIVE

Toxicogenomics was carried out to identify early molecular markers for events in pulmonary injury resulting from tobacco smoke components (TSC) exposure.

MATERIALS AND METHODS

EpiAirway-100 cells were exposed at the air/liquid interface to representative particle (nicotine; cadmium) and vapour phase [formaldehyde (FA) and ethyl carbamate] components of cigarette smoke. Microarray technology was used to compare expression profiles of human genes associated with toxicity and drug resistance, from control and TSC-treated respiratory epithelium (n=5/dose).

RESULTS

Using the GEArray 'toxicology and drug resistance' microarray followed by significance analysis of microarray analysis, 42 mRNA transcripts were found to be significantly altered by the TSC exposure. The vapour [ethyl carbamate, FA and particle (nicotine, cadmium)] phase TSC exhibited differential transcriptional responses that could not be attributed to their chemical phase. The transcriptional changes could be classified according to a functional family, where ethyl carbamate, FA and cadmium classified as carcinogens, demonstrated the highest gene homology when compared with the noncarcinogen, nicotine.

DISCUSSION

Analysis of the microarray data and further confirmation (reverse transcriptase-PCR) identified three potential biomarkers for TSC-induced injury. These three genes (CYP7A1, HMOX1 and PTGS1) are highly upregulated and have been linked with mechanistic pathways of disease.

Induction of drug resistance and transformation in human cancer cells by the noncoding RNA CUDR

Refractory to apoptosis induced by anticancer drugs is one of the major causes of drug resistance in human cancers. The involvement of noncoding RNA (ncRNA) in cancer cell drug resistance has not yet been reported. By using the technique of RT-PCR-based differential display, a novel gene, cancer up-regulated drug resistant (CUDR) gene, was found to be overexpressed in a doxorubicin-resistant subline of human squamous carcinoma A431 and A10A cells, which were also more resistant to drug-induced apoptosis. The full-length CUDR mRNA transcript is approximately 2.2 kb as detected by Northern blot analysis and has no sequence homology with other genes identified so far. Interestingly, no distinct open reading frame was found throughout the CUDR cDNA sequence, and no recombinant protein was detected from in vitro translation or from a protein lysate of human cancer cells after CUDR transfection. Therefore, CUDR is likely to exert its function as a noncoding RNA. Stable transfection with the CUDR gene was found to induce resistance to doxorubicin and etoposide as well as drug-induced apoptosis in A431 cells. By Western blot analysis, down-regulations of caspase 3 were observed in CUDR transfectants. On the other hand, overexpression of CUDR promoted anchorage-independent growth in A431 cells. Results from the present study suggest that CUDR may likely regulate the drug sensitivity and promote cellular transformation at least through caspase 3-dependent apoptosis.

Experimental methods to study human transplacental exposure to genotoxic agents

Human placenta differs more than any other organ between species. This is the primary reason to develop models utilizing human tissue to study placental functions. There are no major ethical restrictions using human placenta for scientific studies. Also, the size of human placenta enables a great number of different parameters to be studied in one placenta. The most important cell types considering transplacental transfer, are the trophoblasts differentiating into syncytiotrophoblasts facing maternal circulation, and endothelial cells of fetal vessels. Primary trophoblasts are difficult to culture and do not grow in monolayer thus inhibiting studies on the polarized functions of transport. Several cell lines originating from trophoblasts have been developed, of which BeWo cells seem most useful for transport studies, because they grow in a tight monolayer. Placental tissue can also be retained as explant cultures, although the trophoblast viability is very restricted despite of culture conditions. Cotyledons of human placenta can be retained viable in an isolated organ perfusion. Perfused placental tissue stays viable longer than placental tissue in tissue culture. Although human placental perfusion is the most tedious experimental method to study placental functions, there are several good reasons to develop it further: transplacental transfer and molecular mechanisms of genotoxic compounds can be studied. Placental perfusion is the only experimental method that retains fully the structure of placenta for polarized transport. Furthermore, perfusion of placentas from mothers, who smoke, use illegal drugs or have a disease, allows studies on the impact of such factors on fetal exposure to genotoxic agents.

Differential expression profiling of genes in a complete hydatidiform mole using cDNA microarray analysis

OBJECTIVES

To gain a better understanding of the genes involved in the pathogenesis of gestational trophoblastic diseases, we evaluated the genome-wide expression levels of genes in complete hydatidiform mole (H-mole) as compared to normal placenta using cDNA microarray technique.

METHODS

The expression profiles of complete H-mole tissues were compared with those of normal placenta using cDNA microarray technique. The data obtained from 10,305 human genes were normalized by the print-tip-based LOWESS method. Significance analysis of microarray (SAM) was used to identify genes with statistically significant changes in expression. The expression levels of genes which showed significant differences between normal early placenta and complete H-mole tissues were further confirmed by RT-PCR.

RESULTS

A cDNA microarray analysis consisting of 10,305 human genes revealed significant changes in the expression of 213 genes, with 91 genes being upregulated and 122 being downregulated. SAM revealed significant changes in gene expression, including those associated with signal transduction, cell structure, transcription, and apoptosis. Further RT-PCR analysis of altered gene expression in mole tissues supported the microarray analysis results. We confirmed the upregulation of TLE4, CAPZA1, PRSS25, RNF130, and USP1 in complete H-mole tissues. Moreover, our study provides the first evidence that ELK3, LAMA3, LNK, STAT2, and TNFRSF25 are downregulated in complete H-mole compared to normal early placenta tissues.

CONCLUSIONS

These findings provide a large body of information regarding gene expression profiles associated with complete H-mole tumorigenesis and allow the identification of potential targets for tumor prevention or therapy.