Common deleted region on the long arm of chromosome 5 in esophageal carcinoma

Roles of Interferon Regulatory Factor 1 in Tumor Progression and Regression: Two Sides of a Coin

IRF1 is a transcription factor well known for its role in IFN signaling. Although IRF1 was initially identified for its involvement in inflammatory processes, there is now evidence that it provides a function in carcinogenesis as well. IRF1 has been shown to affect several important antitumor mechanisms, such as induction of apoptosis, cell cycle arrest, remodeling of tumor immune microenvironment, suppression of telomerase activity, suppression of angiogenesis and others. Nevertheless, the opposite effects of IRF1 on tumor growth have also been demonstrated. In particular, the "immune checkpoint" molecule PD-L1, which is responsible for tumor immune evasion, has IRF1 as a major transcriptional regulator. These and several other properties of IRF1, including its proposed association with response and resistance to immunotherapy and several chemotherapeutic drugs, make it a promising object for further research. Numerous mechanisms of IRF1 regulation in cancer have been identified, including genetic, epigenetic, transcriptional, post-transcriptional, and post-translational mechanisms, although their significance for tumor progression remains to be explored. This review will focus on the established tumor-suppressive and tumor-promoting functions of IRF1, as well as the molecular mechanisms of IRF1 regulation identified in various cancers.

PANoptosis: Mechanisms, biology, and role in disease

Cell death can be executed through distinct subroutines. PANoptosis is a unique inflammatory cell death modality involving the interactions between pyroptosis, apoptosis, and necroptosis, which can be mediated by multifaceted PANoptosome complexes assembled via integrating components from other cell death modalities. There is growing interest in the process and function of PANoptosis. Accumulating evidence suggests that PANoptosis occurs under diverse stimuli, for example, viral or bacterial infection, cytokine storm, and cancer. Given the impact of PANoptosis across the disease spectrum, this review briefly describes the relationships between pyroptosis, apoptosis, and necroptosis, highlights the key molecules in PANoptosome formation and PANoptosis activation, and outlines the multifaceted roles of PANoptosis in diseases together with a potential for therapeutic targeting. We also discuss important concepts and pressing issues for future PANoptosis research. Improved understanding of PANoptosis and its mechanisms is crucial for identifying novel therapeutic targets and strategies.

Human inborn errors of immunity associated with IRF4

The transcription factor interferon regulatory factor 4 (IRF4) belongs to the IRF family and has several important functions for the adaptive immune response. Mutations affecting IRF family members IRF1, IRF3, IRF7, IRF8, or IRF9 have been described in patients presenting with inborn errors of immunity (IEI) highlighting the importance of these factors for the cellular host defense against mycobacterial and/or viral infections. IRF4 deficiency and haploinsufficiency have been associated with IEI. More recently, two novel IRF4 disease-causing mechanisms have been described due to the characterization of IEI patients presenting with cellular immunodeficiency associated with agammaglobulinemia. Here, we review the phenotypes and physiopathological mechanisms underlying IEI of IRF family members and, in particular, IRF4.

The IRF family of transcription factors: Inception, impact and implications in oncogenesis

Members of the interferon-regulatory factor (IRF) proteins family were originally identified as transcriptional regulators of the Type I interferon system. Thanks to consistent advances made in our understanding of the immunobiology of innate receptors, it is now clear that several IRFs are critical for the elicitation of innate pattern recognition receptors, and—as a consequence—for adaptive immunity. In addition, IRFs have attracted great attentions as they modulate cellular responses that are involved in tumorigenesis. The regulation of oncogenesis by IRFs has important implications for understanding the host susceptibility to several Types of cancers, their progression, as well as the potential for therapeutic interventions.

Interferon regulatory factor 1 regulates PANoptosis to prevent colorectal cancer

Interferon regulatory factor 1 (IRF1) regulates diverse biological functions, including modulation of cellular responses involved in tumorigenesis. Genetic mutations and altered IRF1 function are associated with several cancers. Although the function of IRF1 in the immunobiology of cancer is emerging, IRF1-specific mechanisms regulating tumorigenesis and tissue homeostasis in vivo are not clear. Here, we found that mice lacking IRF1 were hypersusceptible to colorectal tumorigenesis. IRF1 functions in both the myeloid and epithelial compartments to confer protection against AOM/DSS-induced colorectal tumorigenesis. We further found that IRF1 also prevents tumorigenesis in a spontaneous mouse model of colorectal cancer. The attenuated cell death in the colons of Irf1-/- mice was due to defective pyroptosis, apoptosis, and necroptosis (PANoptosis). IRF1 does not regulate inflammation and the inflammasome in the colon. Overall, our study identified IRF1 as an upstream regulator of PANoptosis to induce cell death during colitis-associated tumorigenesis.

Interferon regulatory factor 1 inactivation in human cancer

Interferon regulatory factors (IRFs) are a group of closely related proteins collectively referred to as the IRF family. Members of this family were originally recognized for their roles in inflammatory responses; however, recent research has suggested that they are also involved in tumor biology. This review focusses on current knowledge of the roles of IRF-1 and IRF-2 in human cancer, with particular attention paid to the impact of IRF-1 inactivation. The different mechanisms underlying IRF-1 inactivation and their implications for human cancers and the potential importance of IRF-1 in immunotherapy are also summarized.

The clinical significance and biological function of interferon regulatory factor 1 in cholangiocarcinoma

Interferon regulatory factor 1 (IRF1) has been suggested to act as a tumor suppressor in human cancers. However, the clinical significance and biological function of IRF1 in cholangiocarcinoma is poorly understood. In our results, IRF1 mRNA and protein expressions were decreased in cholangiocarcinoma tissues and cell lines compared with paired normal hepatic tissues and intrahepatic bile duct epithelial cell line. IRF1 protein low-expression was associated with tumor stage, tumor size, vascular invasion and metastasis and served as a poor independent prognostic parameter in cholangiocarcinoma patients. Up-regulation of IRF1 expression suppressed cholangiocarcinoma cells proliferation, migration and invasion, and blocked cell cycle progression, but has no effect on apoptosis. In conclusion, IRF1 is low-expressed in cholangiocarcinoma tissues and cell lines, and correlated with malignant status and prognosis in cholangiocarcinoma patients. IRF1 served as tumor suppressor in the regulation of cholangiocarcinoma cells proliferation, cell cycle, migration and invasion.

Identification of IRF1 as critical dual regulator of Smac mimetic-induced apoptosis and inflammatory cytokine response

Smac (second mitochondria-derived activator of caspase) mimetics are considered as promising anticancer therapeutics and used to induce apoptosis by antagonizing inhibitor of apoptosis proteins, which are often abundantly expressed in cancer cells. Here, we identify interferon regulatory factor 1 (IRF1) as a novel critical regulator of Smac mimetic BV6-induced apoptosis and proinflammatory cytokine secretion with impact on the immune response. IRF1 knockdown rescues cells from BV6-induced apoptosis and attenuates BV6-stimulated upregulation of tumor necrosis factor-α (TNFα), indicating that IRF1 mediates BV6-triggered cell death, at least in part, by inducing TNFα. This notion is supported by data showing that exogenous supply of TNFα restores BV6-induced cell death in IRF-knockdown cells. Interestingly, IRF1 selectively controls the induction of nuclear factor-κB (NF-κB) target genes, as IRF1 depletion attenuates BV6-stimulated upregulation of TNFα and interleukin-8 (IL-8) but not p100 and RelB. Concomitant knockdown of IRF1 and p65 cooperate to inhibit BV6-induced cell death, implying a cooperative interaction of IRF1 and NF-κB. In addition, IRF1 silencing hampers TNFα induction by TNFα itself as an another prototypical NF-κB stimulus. Importantly, IRF1 depletion impedes BV6-stimulated secretion of additional proinflammatory cytokines such as granulocyte–macrophage colony-stimulating factor (GM-CSF), IL-8, IL-6 and monocyte chemoattractant protein-1, and migration of primary monocytes to BV6-treated tumor cells. In conclusion, this identification of IRF1 as a dual regulator of BV6-induced apoptosis and inflammatory cytokine secretion provides novel insights into determinants of sensitivity towards Smac mimetic and possible implications of Smac mimetic treatment on tumor microenvironment and immune response.

Restoration of IRF1-dependent anticancer effects by MEK inhibition in human cancer cells

Interferon regulatory factor (IRF1) is a potent antiviral, antitumor and immune regulatory protein. Recently, we found that activated Ras/MEK inhibits antiviral response by downregulating IRF1 expression and renders cancer cells susceptible to oncolytic viruses. In this study, we sought to determine whether IRF1 downregulation underlies oncogenesis induced by Ras/MEK activation in human cancer cells. Treatment of the MEK inhibitor U0126 promoted IRF1 expression in 7 of 11 cancer cell lines we tested. IRF1 promotion was also observed in human cancer cell lines treated with different MEK inhibitors or with RNAi oligonucleotides against extracellular signal-regulated kinases (ERKs). Restoration of the expression of antitumor genes, p27 and p53 upregulated modulator of apoptosis (PUMA), by MEK inhibition was less in IRF1 shRNA knockdown cancer cells than in vector control cancer cells, suggesting that Ras/MEK targets IRF1 for the downregulation of the antitumor genes. Moreover, apoptosis induction by U0126 was significantly reduced in IRF1 shRNA knockdown cells than vector control cells. This study demonstrates that IRF1 expression is suppressed by activated Ras/MEK in human cancer cells and that IRF1 plays essential roles in apoptosis induced by Ras/MEK inhibition.

Function and mechanism by which interferon regulatory factor-1 inhibits oncogenesis

The present review focuses on recent advances in the understanding of the molecular mechnisms by which interferon regulatory factor (IRF)-1 inhibits oncogenesis. IRF-1 is associated with regulation of interferon α and β transcription. In addition, numerous clinical studies have indicated that IRF-1 gene deletion or rearrangement correlates with development of specific forms of human cancer. IRF-1 has been revealed to exhibit marked functional diversity in the regulation of oncogenesis. IRF-1 activates a set of target genes associated with regulation of the cell cycle, apoptosis and the immune response. The role of IRF-1 in the regulation of various types of human tumor has important implications for understanding the susceptibility and progression of cancer. In addition, an improved understanding of the role of IRF-1 in the pathological processes that lead to human malignant diseases may aid development of novel therapeutic strategies.

Global gene expression changes in human urothelial cells exposed to low-level monomethylarsonous acid

Bladder cancer has been associated with chronic arsenic exposure. Monomethylarsonous acid [MMA(III)] is a metabolite of inorganic arsenic and has been shown to transform an immortalized urothelial cell line (UROtsa) at concentrations 20-fold less than arsenite. MMA(III) was used as a model arsenical to examine the mechanisms of arsenical-induced transformation of urothelium. A microarray analysis was performed to assess the transcriptional changes in UROtsa during the critical window of chronic 50nM MMA(III) exposure that leads to transformation at 3 months of exposure. The analysis revealed only minor changes in gene expression at 1 and 2 months of exposure, contrasting with substantial changes observed at 3 months of exposure. The gene expression changes at 3 months were analyzed showing distinct alterations in biological processes and pathways such as a response to oxidative stress, enhanced cell proliferation, anti-apoptosis, MAPK signaling, as well as inflammation. Twelve genes selected as markers of these particular biological processes were used to validate the microarray and these genes showed a time-dependent changes at 1 and 2 months of exposure, with the most substantial changes occurring at 3 months of exposure. These results indicate that there is a strong association between the acquired phenotypic changes that occur with chronic MMA(III) exposure and the observed gene expression patterns that are indicative of a malignant transformation. Although the substantial changes that occur at 3 months of exposure may be a consequence of transformation, there are common occurrences of altered biological processes between the first 2 months of exposure and the third, which may be pivotal in driving transformation.

The Role of Interferon Regulatory Factor-1 (IRF1) in Overcoming Antiestrogen Resistance in the Treatment of Breast Cancer

Resistance to endocrine therapy is common among breast cancer patients with estrogen receptor alpha-positive (ER+) tumors and limits the success of this therapeutic strategy. While the mechanisms that regulate endocrine responsiveness and cell fate are not fully understood, interferon regulatory factor-1 (IRF1) is strongly implicated as a key regulatory node in the underlying signaling network. IRF1 is a tumor suppressor that mediates cell fate by facilitating apoptosis and can do so with or without functional p53. Expression of IRF1 is downregulated in endocrine-resistant breast cancer cells, protecting these cells from IRF1-induced inhibition of proliferation and/or induction of cell death. Nonetheless, when IRF1 expression is induced following IFNγ treatment, antiestrogen sensitivity is restored by a process that includes the inhibition of prosurvival BCL2 family members and caspase activation. These data suggest that a combination of endocrine therapy and compounds that effectively induce IRF1 expression may be useful for the treatment of many ER+ breast cancers. By understanding IRF1 signaling in the context of endocrine responsiveness, we may be able to develop novel therapeutic strategies and better predict how patients will respond to endocrine therapy.

Regulation of immunity and oncogenesis by the IRF transcription factor family

Nine interferon regulatory factors (IRFs) compose a family of transcription factors in mammals. Although this family was originally identified in the context of the type I interferon system, subsequent studies have revealed much broader functions performed by IRF members in host defense. In this review, we provide an update on the current knowledge of their roles in immune responses, immune cell development, and regulation of oncogenesis.

Progressive chromatin repression and promoter methylation of CTNNA1 associated with advanced myeloid malignancies

Complete loss or deletion of the long arm of chromosome 5 is frequent in myelodysplastic syndrome (MDS) and acute myelogenous leukemia (AML). The putative gene(s) deleted and responsible for the pathogenesis of these poor prognosis hematologic disorders remain controversial. This study is a comprehensive analysis of previously implicated and novel genes for epigenetic inactivation in AML and MDS. In 146 AML cases, methylation of CTNNA1 was frequent, and more common in AML patients with 5q deletion (31%) than those without 5q deletion (14%), whereas no methylation of other 5q genes was observed. In 31 MDS cases, CTNNA1 methylation was only found in high-risk MDS (>or=RAEB2), but not in low-risk MDS (<RAEB2), indicating that CTNNA1 methylation might be important in the transformation of MDS to AML. CTNNA1 expression was lowest in AML/MDS patients with CTNNA1 methylation, although reduced expression was found in some patients without promoter methylation. Repressive chromatin marks (H3K27me3) at the promoter were identified in CTNNA1-repressed AML cell lines and primary leukemias, with the most repressive state correlating with DNA methylation. These results suggest progressive, acquired epigenetic inactivation at CTNNA1, including histone modifications and promoter CpG methylation, as a component of leukemia progression in patients with both 5q- and non-5q- myeloid malignancies.

Frequent loss of heterozygosity at the interferon regulatory factor-1 gene locus in breast cancer

The interferon regulatory factor-1 (IRF1) gene, localized on chromosome 5q31.1, is mutated or rearranged in several cancers including some hematopoietic and gastric cancers. However, whether loss of IRF1 occurs in sporadic breast cancer is unknown. Loss of 5q12-31 is reported in 11% of sporadic breast cancers, and high-resolution array-CGH studies have shown loss at 5q31.1 in 50% of breast cancers with a mutated BRCA1 gene. Functionally, overexpression of IRF1 reduces, and a dominant negative IRF1 construct increases, tumorigenesis of human breast cancer xenografts. Taken together, these observations indicate that the IRF1 gene may play a potentially important role as a breast cancer tumor suppressor gene. In this study, we investigated allelic loss of the IRF1 gene in breast tumor specimens from 52 women with invasive breast cancer using an IRF1 intragenic dinucleotide polymorphic marker. Thirty-seven cases were informative. LOH at the IRF1 locus was detected in 32% of these informative cases (12/37). There was a significant association between IRF1 loss and both older age (P = 0.0167) and earlier stage (Stages 1 and 2) (P = 0.0165). To assess the association of IRF1 mRNA expression with clinical outcomes in breast cancer, we studied data from two published gene expression microarray datasets. In breast cancer patients, low IRF1 mRNA expression is strongly correlated with both risk of recurrence (OR = 3.00; P = 0.003; n = 273 cases) and risk of death (OR = 4.18; P = 0.004; n = 191 cases). Our findings strongly imply a tumor suppressor role for the IRF1 gene in breast cancer.

Loss of heterozygosities in Barrett esophagus, dysplasia, and adenocarcinoma detected by esophageal brushing cytology and gastroesophageal biopsy

BACKGROUND

Esophageal brushing cytology (EBC) and gastroesophageal biopsy (GEB) are complementary procedures for the evaluation of gastroesophageal lesions that help guide surveillance and treatment.

METHODS

The authors investigated loss of heterozygosity (LOH) of 17 microsatellite repeat markers near tumor suppressor genes in gastroesophageal lesions on 34 concomitant EBCs and GEBs.

RESULTS

The results indicated that there was progressive accumulation of LOHs toward malignant transformation. EBC samples a greater area than GEB, and more LOHs are detected by EBC than GEB. The combination of cytomorphology and detection of LOHs can improve diagnostic accuracy and is a more useful methodology with which to evaluate gastroesophageal lesions than either EBC or GEB alone. The authors also found that LOHs at 1p36, 9p21, and 17p13 may play an important role in Barrett esophagus (BE), LOHs at 10q23, 17p13, and 17q12 in low-grade dysplasia (LGD), LOHs at 5q23 and 17q21 in high-grade dysplasia (HGD), and LOHs at 5q23 and 21q22 in adenocarcinoma.

CONCLUSIONS

Detection of LOHs targeting tumor suppressor genes can be useful in evaluating gastroesophageal lesions, studying oncogenesis of gastroesophageal adenocarcinoma, and, in combination with EBC and GEB, determining surveillance for BE and LGD and/or treatment for HGD and adenocarcinoma.

The IRF family transcription factors in immunity and oncogenesis

The interferon regulatory factor (IRF) family, consisting of nine members in mammals, was identified in the late 1980s in the context of research into the type I interferon system. Subsequent studies over the past two decades have revealed the versatile and critical functions performed by this transcription factor family. Indeed, many IRF members play central roles in the cellular differentiation of hematopoietic cells and in the regulation of gene expression in response to pathogen-derived danger signals. In particular, the advances made in understanding the immunobiology of Toll-like and other pattern-recognition receptors have recently generated new momentum for the study of IRFs. Moreover, the role of several IRF family members in the regulation of the cell cycle and apoptosis has important implications for understanding susceptibility to and progression of several cancers.

Interferon regulatory factor family of transcription factors and regulation of oncogenesis

A family of transcription factors, the interferon regulatory factors (IRF), was identified originally in the context of the regulation of the type I interferon (IFN)-alpha/beta system. The IRF family has now expanded to nine members, and gene-disruption studies have revealed the critical involvement of these members in multiple facets of host defense systems, such as innate and adaptive immune responses and tumor suppression. In the present review article, we aim at summarizing our current knowledge of the roles of IRF in host defense, with special emphasis on their involvement in the regulation of oncogenesis.

Central role of interferon regulatory factor-1 (IRF-1) in controlling retinoic acid inducible gene-I (RIG-I) expression

Retinoic acid inducible gene-I (RIG-I) functions as the first line of defense against viral infection by sensing dsRNA and inducing type I interferon (IFN) production. The expression of RIG-I itself is induced by IFN-alpha/beta and dsRNA. To comprehend the molecular mechanism of expression regulation, we cloned the RIG-I promoter and analyzed its activity upon IFN-beta and dsRNA treatment. Under basal condition, RIG-I mRNA level and promoter activity were significantly higher in normal cells versus their tumor counterparts. In both normal and cancer cells, RIG-I expression was induced by IFN-beta and dsRNA. A single IRF-1 binding site in the proximal promoter functioned as a crucial regulator of basal, IFN-beta- and dsRNA-mediated induction of the RIG-I promoter. IFN-beta and dsRNA treatment increased IRF-1 binding to the RIG-I promoter. IRF-1 expression was also higher in normal cells than in cancer cells and it was induced by IFN-beta with similar kinetics as RIG-I. These results confirm that by controlling RIG-I expression, IRF-1 plays an essential role in anti-viral immunity. IRF-1 is a tumor suppressor and the expression profile of RIG-I together with its regulation by IRF-1 and the presence of a caspase-recruitment domain in RIG-I suggest that RIG-I might also possess tumor suppressor properties.

Considerations for targeting malignant stem cells in leukemia

BACKGROUND

Malignant stem cells have been identified in acute myelogenous leukemia, chronic myeloid leukemia, and some types of acute lymphoblastic leukemia. Like normal stem cells, these leukemic stem cells (LSCs) are able to self-renew, differentiate, and proliferate extensively. Evidence suggests that LSCs are critical for the initiation and perpetuation of leukemic disease.

METHODS

We reviewed the literature describing the characteristic features of LSCs in various leukemias and the novel molecular approaches being used to specifically ablate the LSC population.

RESULTS

Studies have demonstrated the potential importance of ablating LSCs when treating leukemia. The unique characteristics of LSCs that differentiate them from their normal counterparts can be exploited to specifically target the malignant population.

CONCLUSIONS

Current therapeutic strategies may not effectively ablate the LSC, leaving the potential for disease progression or relapse. A better understanding of LSC cell and molecular biology will allow the design of more effective therapies.

Short tandem repeat polymorphism in exon 4 of esophageal cancer-related gene 2 detected in genomic DNA is a prognostic marker for esophageal cancer

BACKGROUND

Short tandem repeat (STR) polymorphisms in exon 4 of the esophageal cancer-related gene 2 (ECRG2) are a risk marker for esophageal carcinoma. The aim of the present study was to correlate these STRs with clinical outcome.

METHODS

Genomic DNA of 86 patients who underwent complete surgical resection was analyzed for STRs TCA3/TCA3, TCA3/TCA4, and TCA4/TCA4 in exon 4 of ECRG2 by polymerase chain reaction and DNA sequencing.

RESULTS

ECRG2 STR TCA3/TCA3 and TCA3/TCA4 were found in 40 (47%) patients, respectively, and TCA4/TCA4 in 6 (7%) cases. TCA3/TCA3 genotype was significantly associated with reduced survival (P < .05, log-rank test). TCA3/TCA3 STR was the strongest prognostic factor determined by multivariate Cox regression analysis.

CONCLUSIONS

Genetically fixed STR polymorphism TCA3/TCA3 in exon 4 of ECRG2 is associated with poor clinical outcome in surgically treated esophageal cancer patients and might be a potential prognostic marker. The usefulness of these genetic markers to predict responsiveness toward neoadjuvant treatment of esophageal cancer patients would be of high clinical interest and should be examined in future studies.

Involvement of IFN regulatory factor (IRF)-1 and IRF-2 in the formation and progression of human esophageal cancers

IFN regulatory factor (IRF)-1 and IRF-2 are generally regarded as a tumor suppressor and an oncoprotein, respectively. However, little is known about their expression and function in esophageal squamous cell carcinomas (ESCC). In our present work, IRF-1 expression was decreased and IRF-2 expression was increased in ESCCs compared with matched normal esophageal tissues. Moreover, statistical data indicated that IRF-2 expression was tightly correlated with progression of ESCCs. As expected, overexpression of either IRF-1 or IRF-2 in an ESCC cell line resulted in either suppression or enhancement of cell growth, respectively. Also, proliferation- and apoptosis-related molecules (p21(WAF1/CIP1), cyclin-D1, Bcl-2, and histone H4) were regulated by IRF-1 and IRF-2. Additionally, high levels of IRF-2 blocked the function of IRF-1 by preventing the latter from translocating into the nucleus; in contrast, knock down of IRF-2 by small interfering RNA permitted nuclear localization and activity of IRF-1. In vivo assay using nude mice indicated that the tumorigenicity of ESCC cells was enhanced with IRF-2 overexpression but dramatically attenuated after forced expression of IRF-1. In conclusion, IRF-1 and IRF-2 are able to regulate tumorigenicity of ESCC cells as antioncoprotein and oncoprotein, respectively. Relative amounts of IRF-1 to IRF-2 are functionally very important for the development and progression of ESCCs, and reduction of the ratio of IRF-1/IRF-2 may lead to the enhancement of tumorigenicity of ESCC cells. Therefore, levels of IRF-1 and IRF-2 are useful indicators in diagnosis and prognosis for ESCCs, and these molecules are potential drug targets for ESCC therapy.

Short tandem repeat polymorphism in exon 4 of esophageal cancer related gene 2 predicts relapse of oral squamous cell carcinoma

Short tandem repeat (STR) polymorphisms in exon 4 of esophageal cancer related gene 2 (ECRG2) are a prognostic marker for squamous cell carcinoma (SCC) of the esophagus. The aim of the present study was to correlate these STRs with clinical outcome of the similar tumor type oral squamous cell carcinoma (OSCC). DNA of 81 patients that underwent complete surgical resection of OSCC was analyzed for STRs TCA3/TCA3, TCA3/TCA4 and TCA4/TCA4 in exon 4 of ECRG2 by PCR, capillary electrophoresis and DNA sequencing. ECRG2 STR TCA3/TCA3 were found in 45 (56%), TCA3/TCA4 in 33 (41%) and TCA4/TCA4 in 3 (3%) patients. TCA3/TCA3 was significantly associated with reduced relapse-free survival of OSCC, compared with TCA3/TCA4 and TCA4/TCA4 genotypes (P<0.05; log-rank test). TCA3/TCA3 STR was independent prognostic factor determined by multivariate Cox regression analysis (p<0.05). STR polymorphism TCA3/TCA3 in exon 4 of ECRG2 is associated with poor relapse-free survival in surgically completely resected OSCC patients and might be a potential prognostic marker.

A novel repressor domain is required for maximal growth inhibition by the IRF-1 tumor suppressor

Interferon regulatory factor-1 (IRF-1) is a transcription factor and tumor suppressor that can regulate gene expression in a manner requiring either its sequence specific DNA binding activity or its ability to bind the p300 coactivator. We show that IRF-1-mediated growth inhibition is dependent on the integrity of a C-terminal transcriptional enhancer domain. An enhancer subdomain (amino acids 301-325) that differentially regulates IRF-1 activity has been identified and this region mediates the repression of Cdk2. The repressor domain encompasses an LXXLL coregulator signature motif and mutations or deletions within this region completely uncouple transcriptional activation from repression. The loss of growth suppressor activity when the Cdk2-repressor domain of IRF-1 is mutated implicates repression as a determinant of its maximal growth inhibitory potential. The data link IRF-1 regulatory domains to its growth inhibitory activity and provide information about how differential gene regulation may contribute to IRF-1 tumor suppressor activity.

Microsatellite analysis of the APC gene and immunoexpression of E-cadherin, catenin, and tubulin in esophageal squamous cell carcinoma

The histological features that accompany the development and progression of solid tumors are known to be controlled by a distinct cascade of molecular events. One such event is the inactivation of tumor suppressor genes, such as the adenomatous polyposis coli (APC) gene. Disruption of the cadherin-catenin cell adhesion complex also plays a role in the initial steps of cancer invasion and metastasis whereas alterations in cell structural molecules, such as tubulin, may contribute to the cancer phenotype. The understanding of the status of these molecules in ESSC may provide novel markers that could impact on management of the disease. The present study examined alterations in the microsatellite sequence of the APC gene via fluorescent-based polymerase chain reaction in 100 cases of primary esophageal squamous cell carcinoma. In addition, the expression of E-cadherin, alpha- and beta-catenin, and alpha- and beta-tubulin was analyzed using immunohistochemistry. These data were then statistically compared with each other as well as the relevant clinicopathologic data. Although the APC markers (D5S210, D5S346, D5S299, and D5S82) tested did show an overall high frequency of allelic imbalance/loss of heterozygosity (62.48%) and microsatellite instability (41.27%), they did not show prognostic significance in the study cohort and were not correlated with the immunohistochemical data. The tubulin proteins showed no significant change in expression in the tumor tissue The decreased immunoreactivity of E-cadherin was statistically correlated with the presence of lymph node metastases (P = .0180). Although alpha- and beta-catenin as well as E-cadherin showed no direct prognostic value, E-cadherin may warrant further investigation as an indirect prognostic indicator by allowing more accurate prediction of lymph node metastases.

Identification of tumor suppressor loci on the long arm of chromosome 5 in pulmonary large cell neuroendocrine carcinoma

BACKGROUND

A recent cytogenetic analysis of non-small cell lung cancer revealed hot-spot regions for deletion on the long arm of chromosome 5 and suggested the existence of putative tumor suppressor genes in that region. However, similar studies on genetic alterations in large cell neuroendocrine carcinoma (LCNEC) have been very limited. To our knowledge, this is the first report to screen for the loss of heterozygosity (LOH) and to examine the location of putative tumor suppressor genes on chromosome 5q in LCNEC.

OBJECTIVES

To identify tumor suppressor loci on chromosome 5q in LCNEC by microsatellite analysis.

PATIENTS AND METHODS

Microsatellite instability and LOH in tumor and normal tissue samples from 13 patients with LCNEC, who had undergone surgical resections, were analyzed by polymerase chain reaction using a panel of 19 microsatellite DNA markers spanning chromosome 5q.

RESULTS

LOH was found in all of the 13 tumors (100%) in at least one informative marker tested. The following four common minimally deleted regions were noticed on chromosome 5q: 5q14.3-q21.1; 5q22.2-q23.1; 5q23.3-q33.2; and 5q35.1-q35.2. Three of 13 individual tumors (23.1%) exhibited shifted bands for at least one of the tested microsatellite markers. Shifted bands occurred in 6 of 224 loci (2.7%) tested.

CONCLUSION

These data suggest the presence of at least four tumor suppressor loci on chromosome 5q in LCNEC, and further investigations into cloning candidate tumor suppressor genes are warranted.

Microsatellite analysis of the adenomatous polyposis coli (APC) gene and immunoexpression of beta catenin in nephroblastoma: a study including 83 cases treated with preoperative chemotherapy

AIMS

To determine whether microsatellite mutations of the adenomatous polyposis coli (APC) gene have pathological or prognostic significance in nephroblastomas and to correlate APC alterations with beta catenin immunoexpression.

METHODS

One hundred nephroblastomas were analysed, 83 of which received preoperative chemotherapy. Normal and tumour DNA was isolated using standard proteinase K digestion and phenol/chloroform extraction from paraffin wax embedded tissue. Polymerase chain reaction using four APC microsatellite markers-D5S210, D5S299, D5S82, and D5S346-was performed and the products analysed. Immunohistochemistry was performed using the LSAB kit with diaminobenzidine as chromogen. Results were correlated with clinicopathological data using the chi(2) test.

RESULTS

Allelic imbalance/loss of heterozygosity was more frequent than microsatellite instability, with 30% of cases showing allelic imbalance/ loss of heterozygosity and 16% showing microsatellite instability. Although there was a significant correlation between the results for individual markers and the clinicopathological data, the overall results do not support a prognostic role for APC in nephroblastoma. Expression of beta catenin was seen in 93% of cases. Staining was predominantly membranous, with epithelium, blastema, and stroma being immunoreactive. Cytoplasmic redistribution was seen in 58% of cases, but no nuclear staining was detected. No significant associations between beta catenin expression and the clinicopathological parameters were found. Kaplan-Meier survival plots showed that patients with loss of membranous staining and pronounced cytoplasmic staining (score, 3) had a significantly shorter survival (p = 0.04; median survival, 5.87 months).

CONCLUSION

Microsatellite analysis of APC and immunoexpression of beta catenin did not provide significant pathological or prognostic information in this cohort of nephroblastomas.

The molecular biology of esophageal adenocarcinoma

BACKGROUND

Barrett's esophagus is an acquired metaplastic change that occurs in the distal esophagus secondary to chronic gastroesophageal reflux. This premalignant condition forms the most important risk factor for developing esophageal adenocarcinoma, which is an extremely aggressive tumor with a 5-year survival rate of less than 25%. Carcinomas that arise in the setting of Barrett's esophagus are thought to develop as part of the metaplasia-dysplasia-carcinoma sequence.

OBJECTIVE

To review the current knowledge on the genomic alterations involved in the development of Barrett's esophagus and its progression to dysplasia and/or cancer.

RESULTS

Several changes in gene structure, gene expression, and protein structure are associated with the progression of Barrett's esophagus to adenocarcinoma. Accumulation of these changes seems to be essential, rather than the exact sequence of these changes. Multiple molecular pathways are involved and interact with each other. Alterations in tumor suppressor genes, amongst which p53 and p16, are early events in the metaplasia-dysplasia-adenocarcinoma sequence, followed by loss of cell cycle checkpoints. Ongoing genomic instability leads to cumulative genetic errors and thereby the generation of multiple clones of transformed cells.

CONCLUSIONS

Within the multistep process of esophageal adenocarcinogenesis, to date no single molecular marker came forward able to predict who will and who will not develop cancer in the setting of Barrett's esophagus. Instead, panels of markers need to be developed in the future allowing to indicate disease progression. Identification of crucial molecular pathways involved in esophageal adenocarcinogenesis would ultimately improve therapy and facilitate development of new treatment strategies.

Identification of a minimal deletion region on chromosome 5q in Chinese esophageal squamous cell carcinomas

The existence of unknown tumor suppressor gene(s) other than the APC gene has been hinted on 5q for esophageal squamous cell carcinoma (ESCC). In order to define minimal deletion intervals on 5q in ESCC and investigate the potential tumor suppressor gene(s), 9 microsatellite markers scattering the region from 5q22 to 5q35 were chosen for loss of heterozygosity (LOH) analysis in 50 primary ESCC from northern China. The results showed that six cases presented coexistence of LOH for three consecutive adjacent chosen markers, suggesting a minimal deletion region covering approximately 272 kb located on 5q23 from D5S1384 to D5S1505. It was a novel deletion region that was so far never reported in ESCC. Significant higher frequencies of LOH were observed in tumors with lower pathological grade at the locus D5S820 and with lymph node metastasis at the locus D5S408. The data suggested the possibility that one or more putative candidate tumor suppressor gene(s) on 5q23 might play an important role in the development and/or progression of ESCC.

Interferon regulatory factor 1 binding to p300 stimulates DNA-dependent acetylation of p53

Interferon regulatory factor 1 (IRF-1) and p53 control distinct sets of downstream genes; however, these two antioncogenic transcription factors converge to regulate p21 gene expression and to inhibit tumor formation. Here we investigate the mechanism by which IRF-1 and p53 synergize at the p21 promoter and show that stimulation of p21 transcription by IRF-1 does not require its DNA-binding activity but relies on the ability of IRF-1 to bind the coactivator p300 and to stimulate p53-dependent transcription by an allosteric mechanism. Deletion of the p300-binding sites in IRF-1 eliminates the ability of IRF-1 to stimulate p53 acetylation and associated p53 activity. Complementing this, small peptides derived from the IRF-1-p300 interface can bind to p300, stabilize the binding of p300 to DNA-bound p53, stimulate p53 acetylation in trans, and up-regulate p53-dependent activity from the p21 promoter. The nonacetylatable p53 mutant (p53-6KR) cannot be stimulated by IRF-1, further suggesting that p53 acetylation is the mechanism whereby IRF-1 modifies p53 activity. These data expand the core p300-p53 protein LXXLL and PXXP interface by including an IRF-1-p300 interface as an allosteric modifier of DNA-dependent acetylation of p53 at the p21 promoter.

Frequent Loss of Heterozygosity but Rare Microsatellite Instability in Oesophageal Cancer in Japanese and Chinese Patients

Reported frequencies for microsatellite instability (MSI) in oesophageal cancer differ widely in the literature, perhaps due to the high incidence of loss of heterozygosity (LOH) in this cancer. Using high-resolution fluorescent microsatellite analysis (HRFMA), we analysed microsatellite alterations in detail in 50 Japanese and 50 Chinese patients with squamous cell carcinoma in the oesophagus. In HRFMA, several devices have been developed to improve the detection characteristics, reproducibility of polymerase chain reaction and the migration accuracy of electrophoresis. All the alterations observed were separable into MSI, LOH and alterations ambiguous for both. MSI was rare in these panels of oesophageal carcinomas. The frequencies of MSI in the Japanese and Chinese subjects were 8 and 4%, respectively. All the alterations were mild (within 2 base pairs) and were observed in a limited number of markers. More drastic types of MSI, such as those typical in colorectal cancer, were not observed. On the other hand, the incidence of LOH was high, reaching 50% for the Japanese and 70% for the Chinese subjects. In many of these cases, LOH was observed in multiple microsatellite markers. The frequency of LOH in each marker was not apparently biased. Although in many cases MSI and LOH were clearly distinguished with use of the sensitive and quantitative fluorescent assay, theoretically indistinguishable patterns were noted in some cases. In conclusion, MSI is rare and LOH predominates in squamous cell carcinoma in the oesophagus.

Marked allelic imbalance on chromosome 5q31 does not explain alpha-catenin expression in epithelial ovarian cancer

OBJECTIVE

Human alpha-catenin gene (CTNNA1) on chromosome 5q31 is aberrantly expressed in various types of cancer including epithelial ovarian tumors. Allelic imbalance on this region has also been described in several malignant diseases. In the present work, the role of CTNNA1 as a candidate tumor suppressor gene was studied by comparing protein expression with allelic imbalance in human epithelial ovarian tumors.

METHODS

Alpha-catenin protein expression was determined from two areas of 41 tumors, and tissues from these areas were microdissected. After DNA extraction, AI analysis was carried out with eight microsatellite markers.

RESULTS

Altogether, 93% of the tumors (38 of 41) showed allelic imbalance at one or more loci. Two distinct common regions of allelic imbalance were identified, one comprising markers D5S2002 and D5S1995 and the other markers D5S393 and D5S476. Loss of the CTNNA1 gene did not appear to be involved in down-regulation of alpha-catenin in ovarian tumors, since allelic imbalance with a variety of markers, including CTNNA1 associated marker D5S476, was found in tumor samples independently of alpha-catenin expression. Furthermore, allelic imbalance analyses of two different samples from the same tumor revealed genetic heterogeneity.

CONCLUSIONS

High allelic imbalance frequency indicates that chromosomal region 5q31 is functionally important in epithelial ovarian cancer. Allelic imbalance occurs at two distinct regions of which one includes the CTNNA1 gene. However, this gene is likely to be inactivated by mechanisms other than allelic imbalance. In addition, genetic heterogeneity observed in these tumors demonstrates the multiclonal nature of epithelial ovarian tumors.

Short tandem repeat polymorphism in a novel esophageal cancer-related gene (ECRG2) implicates susceptibility to esophageal cancer in Chinese population

We have previously cloned and identified a novel esophageal cancer related gene 2 (ECRG2; GenBank Accession Number AF268198), which is down-regulated in esophageal squamous cell carcinoma (ESCC) and involved in the induction of the apoptosis in esophageal cancer cell lines. In the present study, we have found a short tandem repeat (STR) polymorphism in the noncoding region of the exon 4 of the ECRG2 gene by using PCR-denaturing high-performance liquid chromatography (DHPLC). Three STR genotypes, TCA3/TCA3, TCA3/TCA4 and TCA4/TCA4 were revealed and confirmed by DNA sequencing analysis. A total of 661 objects including 228 patients with ESCC and 373 normal controls were analyzed to investigate the impact of this ECRG2 STR polymorphism on risk of ESCC in case-control studies. Genotypes were determined in 231 controls and 162 cases from Beijing, which is a low risk area of ESCC, and in 142 controls and 126 cases from Linxian, a well-known high-risk area of ESCC. In both of the Beijing and Linxian population, subjects who carried the TCA3/TCA3 genotype were at an increased risk of ESCC compared to those carrying the TCA4/TCA4 genotype, with the adjusted odds ratios (ORs) being 2.05 [95% confidence interval (CI), 1.02-4.06] for the subjects from Beijing and 4.40 (95% CI, 1.93-10.01) for the subjects from Linxian. Furthermore, comparison of the genotype distributions among other cancer sites might suggest that risk of the ECRG2 STR polymorphism might be specific to the esophagus. These findings indicate for the first time that the ECRG2 STR is a genetic susceptibility factor for ESCC and the TCA3/TCA3 allele might play a role in the development of this cancer.

Development of CD30+ lymphoproliferative disease in mice lacking interferon regulatory factor-1

Human lymphomas continue to represent a major challenge in oncology, and in particular occur at very high frequencies in AIDS patients. We report here the development of a CD30+ lymphoproliferative disease in mice lacking the proapoptotic transcription factor, interferon regulatory factor-1. These mice most closely represent a model of human anaplastic large-cell lymphoma (ALCL). This mouse model of lymphoma will likely be useful in understanding the development of ALCL and in understanding the development of other closely related CD30+ forms of lymphoma, such as CD30+ Hodgkin's disease and CD30+ cutaneous T-cell lymphoma. This mouse model will also be useful in testing therapies for different forms of CD30+ lymphoma, in particular anti-CD30-based therapies.

Mullerian inhibiting substance promotes interferon gamma-induced gene expression and apoptosis in breast cancer cells

This report demonstrates that in addition to interferons and cytokines, members of the TGF beta superfamily such as Mullerian inhibiting substance (MIS) and activin A also regulate IRF-1 expression. MIS induced IRF-1 expression in the mammary glands of mice in vivo and in breast cancer cells in vitro and stimulation of IRF-1 by MIS was dependent on activation of the NF kappa B pathway. In the rat mammary gland, IRF-1 expression gradually decreased during pregnancy and lactation but increased at involution. In breast cancer, the IRF-1 protein was absent in 13% of tumors tested compared with matched normal glands. Consistent with its growth suppressive activity, expression of IRF-1 in breast cancer cells induced apoptosis. Treatment of breast cancer cells with MIS and interferon gamma (IFN-gamma) co-stimulated IRF-1 and CEACAM1 expression and synergistic induction of CEACAM1 by a combination of MIS and IFN-gamma was impaired by antisense IRF-1 expression. Furthermore, a combination of IFN-gamma and MIS inhibited the growth of breast cancer cells to a greater extent than either one alone. Both reagents alone significantly decreased the fraction of cells in the S-phase of the cell cycle, an effect not enhanced when they were used in combination. However, MIS promoted IFN-gamma-induced apoptosis demonstrating a functional interaction between these two classes of signaling molecules in regulation of breast cancer cell growth.

The role of interferon regulatory factor-1 and interferon regulatory factor-2 in IFN-gamma growth inhibition of human breast carcinoma cell lines

Interferon (IFN) regulatory factor-1 (IRF-1) and IRF-2 play opposing roles in the regulation of many IFN-gamma-inducible genes. To investigate the signal transduction pathway in response to IFN-gamma in light of differences in growth effects, we selected four human breast carcinoma cell lines based on a spectrum of growth inhibition by IFN-gamma. MDA468 growth was markedly inhibited by IFN-gamma, and it showed substantial induction of IRF-1 mRNA but little IRF-2 induction. SKBR3 showed little growth inhibition and little induction of IRF-1 mRNA but significant induction of IRF-2 mRNA. HS578T and MDA436 growth inhibition and IRF-1/IRF-2 induction were intermediate. All four cell lines showed intact receptor at the cell surface and Stat1 translocation to the nucleus by immunostaining. By EMSA, there were marked differences in the induced ratio of IRF-1 and IRF-2 binding activity between the cell lines that correlated with growth inhibition. Finally, antisense oligonucleotides specific for IRF-1 attenuated IFN-gamma growth inhibition in MDA436 and MDA468, confirming the direct role of IRF-1 in IFN-gamma growth inhibition. Induction of IRF-1 causes growth inhibition in human breast cancer cell lines, and induction of IRF-2 can oppose this. The relative induction of IRF-1 to IRF-2 is a critical control point in IFN-gamma response.

Interferon regulatory factor-1 (IRF-1) is a mediator for interferon-gamma induced attenuation of telomerase activity and human telomerase reverse transcriptase (hTERT) expression

Constitutive activation of the telomerase is a key step in the development of human cancers. Interferon-gamma (IFN-gamma) signaling induces growth arrest in many tumors through multiple regulatory mechanisms. In this study, we show that IFN-gamma signaling represses telomerase activity and human telomerase reverse transcriptase (hTERT) transcription, and suggest that this signaling is mediated by IRF-1. Ectopic expression of IRF-1 attenuated hTERT promoter activity. Murine embryonic fibroblasts (MEFs) genetically deficient in IRF-1 (IRF-1(-/-)) showed an elevated level (>15 times) of hTERT promoter activity as compared to the hTERT promoter activity of wild-type MEFs. The telomerase activity and hTERT expression in IRF-1(-/-) MEFs were downregulated by IRF-1 transfection. Interestingly, less extent of telomerase repression was observed in HPV E6 and E7 negative, p53 mutant HT-3 cells than in HPV 18 E6 and E7 positive HeLa cells (intact p53). These findings provide evidence that IRF-1 is a potential mediator of IFN-gamma-induced attenuation of telomerase activity and hTERT expression.

Genome-wide analyses on loss of heterozygosity in head and neck squamous cell carcinomas

Head and neck squamous cell carcinoma (HNSCC) is a frequent malignancy with a poor survival rate. Identifying the tumor suppressor gene (TSG) loci by genomic studies is an important step to uncover the molecular mechanisms involved in HNSCC pathogenesis. We therefore performed comprehensive analyses on loss of heterozygosity (LOH) using a genome-wide panel of 191 microsatellite markers in 22 HNSCC samples. We found 53 markers with significantly high LOH (>30%) on 21 chromosomal arms; the highest values of those were observed on 3p, 9p, 13q, 15q, and 17p, corresponding to D3S2432 (67%), D9S921-D9S925 (67%) and GATA62F03 (86%), D13S1493 (60%), D15S211 (62%), and D17S1353 (88%), respectively. Fifteen hot spots of LOH were defined in 13 chromosomal arms: 2q22-23, 4p15.2, 4q24-25, 5q31, 8p23, 9p23-24, 9q31.3, 9q34.2, 10q21, 11q21-22.3, 14q11-13, 14q22.3, 17p13, 18q11, and 19q12 as loci reported previously in HNSCCs. Furthermore, we identified five novel hot spots of LOH on three chromosomal arms in HNSCC at 2q33 (D2S1384), 2q37 (D2S125), 8q12-13 (D8S1136), 8q24 (D8S1128), and 15q21 (D15S211). In conclusion, our comprehensive allelotype analyses have unveiled and confirmed a total of 20 possible TSG loci that could be involved in the development of HNSCC. These results provide useful clues for identification of putative TSGs involved in HNSCC by fine mapping of the suspected regions and subsequent analysis for functional genes.

Regulation of the IRF-1 tumour modifier during the response to genotoxic stress involves an ATM-dependent signalling pathway

The mechanism by which genotoxic stress induces IRF-1 and the signalling components upstream of this anti-oncogenic transcription factor during the response to DNA damage are not known. We demonstrate that IRF-1 and the tumour suppressor protein p53 are coordinately up-regulated during the response to DNA damage in an ATM-dependent manner. Induction of IRF-1 protein by either ionizing radiation (IR) or etoposide occurs through a concerted mechanism involving increased IRF-1 expression/synthesis and an increase in the half-life of the IRF-1 protein. A striking defect in the induction of both IRF-1 mRNA and IRF-1 protein was observed in ATM deficient cells. Although ATM deficient cells failed to increase IRF-1 in response to genotoxic stress, the induction of IRF-1 in response to viral mimetics remained intact. Re-expression of the ATM kinase in AT cells restored the DNA damage inducibility of IRF-1, whilst the PI-3 kinase inhibitor wortmannin inhibited IRF-1 induction by DNA damage in ATM-positive cells. The data highlight a role for the ATM kinase in orchestrating the coordinated induction and transcriptional cooperation of IRF-1 and p53 to regulate p21 expression. Thus, IRF-1 is controlled by two distinct signalling pathways; a JAK/STAT-signalling pathway in viral infected cells and an ATM-signalling pathway in DNA damaged cells.

Myeloid differentiation (MyD)/growth arrest DNA damage (GADD) genes in tumor suppression, immunity and inflammation

Myeloid differentiation (MyD) primary response and growth arrest DNA damage (Gadd) genes comprise a set of overlapping genes, including known (IRF-1, EGR-1, Jun) and novel (MyD88, Gadd45alpha, MyD118/Gadd45beta, GADD45gamma, MyD116/ Gadd34) genes, that have been cloned by virtue of being co-ordinately induced upon the onset of terminal myeloid differentiation and following exposure of cells to stress stimuli. In recent years it has become evident that MyD/Gadd play a role in blood cell development, where they function as positive regulators of terminal differentiation, lineage-specific blood cell development and control of blood cell homeostasis, including growth inhibition and apoptosis. MyD/Gadd are also involved in inflammatory responses to invading micro-organisms, and response to environmental stress and physiological stress, such as hypoxia, which results in ischemic tissue damage. An intricate network of interactions among MyD/GADD genes and gene products appears to control their diverse functions. Deregulated growth, increased cell survival, compromised differentiation and deficiencies in DNA repair are hallmarks of malignancy and its progression. Thus, the role MyD/Gadd play in negative growth control, including cell cycle arrest and apoptosis, and in DNA repair, make them attractive molecular targets for tumor suppression. The role MyD/Gadd play in innate immunity and host response to hypoxia also make these genes and gene products attractive molecular targets to treat immunity and inflammation disorders, such as septic shock and ischemic tissue damage.

Beta-catenin expression and its association with prognostic factors in adenocarcinoma developed in Barrett esophagus

The majority of the adenocarcinomas arising in Barrett esophagus manifest clinically at an advanced stage and have a poor prognosis. As a result of this poor prognosis, much attention has been directed toward the exploration of markers for neoplastic progression in Barrett esophagus. The objective of the present study was to determine the expression of beta-catenin by immunohistochemical analysis in 70 adenocarcinomas developed in Barrett esophagus and to examine its relationship to various prognostic factors currently in use. Abnormal beta-catenin expression, consisting of the loss of membranous staining and the appearance of the nuclear staining, was found in 43 cases (61%). Of patients with the 43 tumors showing abnormal beta-catenin expression, 25 (58%) survived more than 1 year. In contrast, only 7 (26%) of 27 patients with tumors showing normal beta-catenin expression survived longer than 1 year. Most of the superficial (Tis-T1) tumors (83% [10/12]) exhibited abnormal beta-catenin expression compared with only 53% (31/58) in the T2-T3 group. These results suggest a possible correlation among beta-catenin expression, tumor stage, and length of survival as prognostic factors in patients with adenocarcinoma in Barrett esophagus.

Role of molecular biology in the follow-up of patients who have Barrett's esophagus

At present, the follow-up of patients who have Barrett's esophagus (BE) should occur within the setting of an endoscopic biopsy surveillance program and with the frequency of surveillance as proposed by the American College of Gastroenterology. In the future, patients who have BE will be further stratified according to their risk for progression to invasive carcinoma. This stratification will permit the development of more rational surveillance programs. Models that incorporate epidemiologic risk factors, reflux symptoms, and endoscopic and histologic findings will likely include panels of biomarkers for further stratification of patients as low, intermediate, or high risk. Therefore, the challenge over the next decade will be to define the role of molecular markers in endoscopic surveillance strategies and to identify additional clinically relevant molecular markers for prognosis as intermediate markers for chemoprevention and as molecular targets for novel gene therapies.

IRF-1 as a negative regulator of cell proliferation

Numerous evidence has demonstrated the involvement in growth control of interferon (IFN) regulatory factor-1 (IRF-1), which shows tumor suppressor activity. IRF-1 is a well-studied member of the IRF transcription factors that reveals functional diversity in the regulation of cellular response by activating expression of a diverse set of target genes, depending on the cell type and on the specific stimuli. IRF-1 gene rearrangements may be a crucial point in the pathogenesis of some cancer types. Furthermore, different aspects of the tumor suppressor function of IRF-1 may be explained, at least in part, by the observations that IRF-1 is a regulator of cell cycle and apoptosis and that its inactivation accelerates cell transformation. Studies on gene knockout mice contributed greatly to the clarification of these multiple IRF-1 functions. We summarize our current knowledge of the antigrowth effect of IRF-1, focusing also on a more general involvement of IRF-1 in mediating negative regulation of cell growth induced by numerous cytokines and other biologic response modifiers.

Comparative genomic hybridization of esophageal squamous cell carcinoma: correlations between chromosomal aberrations and disease progression/prognosis

BACKGROUND

Esophageal carcinoma is a major cause of cancer-related deaths among males in Taiwan. However, to date, the genetic alterations that accompany this lethal disease are not understood.

METHODS

Chromosomal aberrations of 46 samples of esophageal squamous cell carcinoma (EC-SCC) were analyzed by comparative genomic hybridization (CGH), and their correlations with pathologic staging and prognosis were analyzed statistically.

RESULTS

In total, 321 gains and 252 losses were found in 46 tumor samples; thus, the average gains and losses per patient were 6.98 and 5.47, respectively. Frequent gain abnormalities were found on chromosome arms 1q, 2q, 3q, 5p, 7p, 7q, 8q, 11q, 12p, 12q, 14q, 17q, 20q, and Xq. Frequent deletions were found on chromosome arms 1p, 3p, 4p, 5q, 8p, 9p, 9q, 11q, 13q, 16p, 17p, 18q, 19p, and 19q. It was found that deletions of 4p and 13q12-q14 and gain of 5p were significantly correlated with pathologic staging. Losses of 8p22-pter and 9p also were found more frequently in patients with advanced disease. Gain of 8q24-qter was seen more frequently in patients with Grade 3 tumors. A univariate analysis found that pathologic staging; gains of 5p and 7q; and deletions of 4p, 9p, and 11q were significant prognostic factors. However, pathologic staging became the only significant factor in a multivariate analysis.

CONCLUSIONS

CGH not only revealed novel chromosomal aberrations in EC-SCC, but also found possible genotypic changes associated with disease progression. Despite all of the possible associations of chromosomal aberrations with disease progression, the most important prognostic factor for patients with EC-SCC was pathologic staging.

IRF family of transcription factors as regulators of host defense

Interferon regulatory factors (IRFs) constitute a family of transcription factors that commonly possess a novel helix-turn-helix DNA-binding motif. Following the initial identification of two structurally related members, IRF-1 and IRF-2, seven additional members have now been reported. In addition, virally encoded IRFs, which may interfere with cellular IRFs, have also been identified. Thus far, intensive functional analyses have been done on IRF-1, revealing a remarkable functional diversity of this transcription factor in the regulation of cellular response in host defense. Indeed, IRF-1 selectively modulates different sets of genes, depending on the cell type and/or the nature of cellular stimuli, in order to evoke appropriate responses in each. More recently, much attention has also been focused on other IRF family members. Their functional roles, through interactions with their own or other members of the family of transcription factors, are becoming clearer in the regulation of host defense, such as innate and adaptive immune responses and oncogenesis.

Molecular biology of Barrett's adenocarcinoma

OBJECTIVE

To review the current knowledge on the genetic alterations involved in the development and progression of Barrett's esophagus-associated neoplastic lesions.

SUMMARY BACKGROUND DATA

Barrett's esophagus (BE) is a premalignant condition in which the normal squamous epithelium of the esophagus is replaced by metaplastic columnar epithelium. BE predisposes patients to the development of esophageal adenocarcinoma. Endoscopic surveillance can detect esophageal adenocarcinomas when they are early and curable, but most of the adenocarcinomas are detected at an advanced stage. Despite advances in multimodal therapy, the prognosis for invasive esophageal adenocarcinoma is poor. A better understanding of the molecular evolution of the Barrett's metaplasia to dysplasia to adenocarcinoma sequence may allow improved diagnosis, therapy, and prognosis.

METHODS

The authors reviewed data from the published literature to address what is known about the molecular changes thought to be important in the pathogenesis of BE-associated neoplastic lesions.

RESULTS

The progression of Barrett's metaplasia to adenocarcinoma is associated with several changes in gene structure, gene expression, and protein structure. Some of the molecular alterations already showed promise as markers for early cancer detection or prognostication. Among these, alterations in the p53 and p16 genes and cell cycle abnormalities or aneuploidy appear to be the most important and well-characterized molecular changes. However, the exact sequence of events is not known, and probably multiple molecular pathways interact and are involved in the progression of BE to adenocarcinoma.

CONCLUSIONS

Further research into the molecular biology of BE-associated adenocarcinoma will enhance our understanding of the genetic events critical for the initiation and progression of Barrett's adenocarcinoma, leading to more effective surveillance and treatment.

Frequent loss of heterozygosity on chromosome 5 in non-small cell lung carcinoma

AIMS

Loss of heterozygosity (LOH) at specific chromosomal regions strongly suggests the existence of tumour suppressor genes at the relevant segment. Frequent LOH on chromosome 5q has been reported in a wide variety of human tumours, including those of the lung. The aim of this study was to screen for LOH and to clarify the location of putative tumour suppressor genes on chromosome 5 implicated in the genesis and/or development of non-small cell lung carcinoma.

METHODS

Thirty three patients with advanced non-small cell lung carcinoma were screened for LOH with a panel of 21 microsatellite DNA markers spanning the entire chromosome 5, using semi-automated fluorochrome based methodology.

RESULTS

Twenty of the non-small cell lung carcinoma samples displayed LOH for one or more informative locus. LOH involving only 5q was found in 10 of 14 of the informative samples. Deletions involving 5p only were not present in the samples under study. There was no evidence of microsatellite instability in any of the analysed loci. These results indicate the presence of five distinct segments displaying high frequencies of deletion on chromosome 5, namely: 5q11.2-q12.2, 5q15 (D5S644 locus), 5q22.3-q23.1, 5q31.1, and 5q35.3. Eight of 14 samples had simultaneous interstitial deletions in at least two different regions. Moreover, concomitant deletion of three and four distinct regions was displayed in three of 14 and two of 14, respectively, of the informative samples.

CONCLUSION

Allelic deletion on chromosome 5 is a frequent event in patients with non-small cell lung carcinoma. These results suggest the involvement of these five regions, either independently or simultaneously, in both lung squamous cell carcinoma and lung adenocarcinoma.