Dimitrios Iliopoulos

E2F1-Regulated MicroRNAs Impair TGFβ-Dependent Cell-Cycle Arrest and Apoptosis in Gastric Cancer

Deregulation of E2F1 activity and resistance to TGFbeta are hallmarks of gastric cancer. MicroRNAs (miRNAs) are small noncoding RNAs frequently misregulated in human malignancies. Here we provide evidence that the miR-106b-25 cluster, upregulated in a subset of human gastric tumors, is activated by E2F1 in parallel with its host gene, Mcm7. In turn, miR-106b and miR-93 regulate E2F1 expression, establishing a miRNA-directed negative feedback loop. Furthermore, upregulation of these miRNAs impairs the TGFbeta tumor suppressor pathway, interfering with the expression of CDKN1A (p21(Waf1/Cip1)) and BCL2L11 (Bim). Together, these results suggest that the miR-106b-25 cluster is involved in E2F1 posttranscriptional regulation and may play a key role in the development of TGFbeta resistance in gastric cancer.

Fragile genes as biomarkers: epigenetic control of WWOX and FHIT in lung, breast and bladder cancer.

This study aimed to (a) determine if DNA methylation is a mechanism of WWOX (WW domain containing oxidoreductase) and FHIT (fragile histidine triad) inactivation in lung, breast and bladder cancers; (b) examine distinct methylation patterns in neoplastic and adjacent tissues and (c) seek correlation of methylation patterns with disease status. Protein expression was detected by immunohistochemistry, and methylation status by methylation-specific PCR (MSP) and sequencing, in lung squamous cell carcinomas and adjacent tissues, invasive breast carcinomas, adjacent tissues and normal mammary tissues and bladder transitional cell carcinomas. Wwox and Fhit expression was reduced in cancers in association with hypermethylation. Differential patterns of WWOX and FHIT methylation were observed in neoplastic vs adjacent non-neoplastic tissues, suggesting that targeted MSP amplification could be useful in following treatment or prevention protocols. WWOX promoter MSP differentiates DNA of lung cancer from DNA of adjacent lung tissue. WWOX and FHIT promoter methylation is detected in tissue adjacent to breast cancer and WWOX exon 1 MSP distinguishes breast cancer DNA from DNA of adjacent and normal tissue. Differential methylation in cancerous vs adjacent tissues suggests that WWOX and FHIT hypermethylation analyses could enrich a panel of DNA methylation markers.

WWOX gene restoration prevents lung cancer growth in vitro and in vivo

The WWOX (WW domain containing oxidoreductase) gene at the common fragile site, FRA16D, is altered in many types of cancer, including lung cancer. We have examined the tumor suppressor function of WWOX in preclinical lung cancer models. The WWOX gene was expressed in lung cancer cell lines through recombinant adenovirus (Ad) infection (Ad-WWOX), and through a drug [ponasterone A, (ponA)]-inducible system. After WWOX restoration in vitro, endogenous Wwox protein-negative cell lines (A549, H460, and H1299) underwent apoptosis through activation of the intrinsic apoptotic caspase cascade in A549 and H460 cells. Ectopic expression of Wwox caused dramatic suppression of tumorigenicity of A549, H460, and H1299 cells in nude mice after Ad-WWOX infection and after ponA induction of Wwox expression in H1299 lung cancer cells. Tumorigenicity and in vitro growth of U2020 (Wwox-positive) lung cancer cells was unaffected by Wwox overexpression. This study confirms that WWOX is a tumor suppressor gene and is highly effective in preventing growth of lung cancer xenografts, whether introduced through viral infection or by induction of a silent WWOX transgene.

Concordant loss of fragile gene expression early in breast cancer development

The FHIT and WWOX genes encompass the FRA3B and FRA16D fragile sites at chromosomes 3p14.2 and 16q23.3, respectively. Reduced Fhit and Wwox expression has been reported in approximately two‐thirds of invasive breast tumors. Expression of these fragile gene products, as well as ErbB2 and p53, were evaluated immunohistochemically in 44 pure and 31 adjacent‐to‐invasive ductal carcinoma in‐situ (DCIS) cases. Reduced Fhit and Wwox expression were observed in (i) 70% and 68% of pure DCIS; (ii) 52% and 55% of DCIS adjacent‐to‐invasive tumor cases; and (iii) 20% and 50% of adjacent normal tissue in pure DCIS cases. Reduced Wwox expression in adjacent normal tissue was observed in 30% of cases in the DCIS adjacent‐to‐invasive group. Reduced Fhit and Wwox expression was observed in 61% of adjoining invasive tumors. In all normal, pure DCIS, and DCIS adjacent‐to‐invasive lesions, Fhit and Wwox expression was positively associated (Pu2003=u20030.034, Pu2003=u20030.042, Pu2003=u20030.004, respectively) and in the invasive component there was a positive trend toward association (Pu2003=u20030.075). Fhit and Wwox were more frequently reduced in high‐grade lesions in the DCIS adjacent‐to‐invasive (Pu2003=u20030.025, Pu2003=u20030.004, respectively). In the pure DCIS group, there was a statistically significant negative association between Fhit and ErbB2 expression in DCIS (Pu2003=u20030.035). In summary, reduced Fhit and Wwox expression in in‐situ breast cancer was associated, which may contribute to the high‐grade DCIS–invasive tumor pathway.

Epigenetic modulation of endogenous tumor suppressor expression in lung cancer xenografts suppresses tumorigenicity

Epigenetic changes involved in cancer development, unlike genetic changes, are reversible. DNA methyltransferase and histone deacetylase inhibitors show antiproliferative effects in vitro, through tumor suppressor reactivation and induction of apoptosis. Such inhibitors have shown activity in the treatment of hematologic disorders but there is little data concerning their effectiveness in treatment of solid tumors. FHIT, WWOX and other tumor suppressor genes are frequently epigenetically inactivated in lung cancers. Lung cancer cell clones carrying conditional FHIT or WWOX transgenes showed significant suppression of xenograft tumor growth after induction of expression of the FHIT or WWOX transgene, suggesting that treatments to restore endogenous Fhit and Wwox expression in lung cancers would result in decreased tumorigenicity. H1299 lung cancer cells, lacking Fhit, Wwox, p16INK4a and Rassf1a expression due to epigenetic modifications, were used to assess efficacy of epigenetically targeted protocols in suppressing growth of lung tumors, by injection of 5‐aza‐2‐deoxycytidine (AZA) and trichostatin A (TSA) in nude mice with established H1299 tumors. High doses of intraperitoneal AZA/TSA suppressed growth of small tumors but did not affect large tumors (200 mm3); lower AZA doses, administered intraperitoneally or intratumorally, suppressed growth of small tumors without apparent toxicity. Responding tumors showed restoration of Fhit, Wwox, p16INKa, Rassf1a expression, low mitotic activity, high apoptotic fraction and activation of caspase 3. These preclinical studies show the therapeutic potential of restoration of tumor suppressor expression through epigenetic modulation and the promise of re‐expressed tumor suppressors as markers and effectors of the responses.

Wwox and Ap2γ Expression Levels Predict Tamoxifen Response

Purpose: Assessment of expression levels of Wwox, Wwox-interacting proteins Ap2α, Ap2γ, and ErbB4, the Ap2γ transcriptional target protein Her2, and the possible Ap2α transcriptional target PrkaRIα, in breast cancers, to determine their roles in tamoxifen resistance. The hypothesis was that sequestration of Wwox interactors in the cytoplasm might control tamoxifen response. Experimental Design: Tissue sections from 51 tamoxifen-sensitive and 38 tamoxifen-resistant, estrogen receptor α–positive breast cancers were stained for the above proteins, as well as progesterone receptor (PR). The relation of tamoxifen resistance and other clinical features, with level of expression of these proteins, and pairwise correlations among various immunohistochemical markers were determined. Results: Menopausal status, tumor, node, and stage, loss of PR, lost or reduced expression of Wwox, and high level of expression of PrkaRIα, Ap2γ, and Her2 were significantly correlated with tamoxifen resistance. In multivariate analysis, Wwox, PrkaRIα, Ap2γ, and ErbB4 were found to be independent markers of tamoxifen resistance. Reduced Wwox expression was better than PR in prediction of resistance, especially in high-risk patients, and nuclear Ap2γ expression was better than Her2, especially in low-risk patients. Conclusion: The results illustrate the complex relationships among the marker proteins assessed in this in vivo study and suggest new markers for prediction of response to tamoxifen treatment as well as possible new targets for treatment of breast cancer. Wwox and Ap2γ emerge as new biomarkers that may be superior to PR and Her2 in predicting tamoxifen response.

Alterations of the tumor suppressor gene ARLTS1 in ovarian cancer.

ARLTS1 is a tumor suppressor gene initially described as a low-penetrance cancer gene: a truncated Trp149Stop (MUT) polymorphism is associated with general familial cancer aggregation and, particularly, high-risk familial breast cancer. DNA hypermethylation has been identified as a mechanism of ARLTS1 expression down-regulation in lung carcinomas and B-cell chronic lymphocytic leukemia. We found that, in the majority of ovarian carcinomas (61.5%) and in a significant proportion of ovarian and breast cancer cell lines (45%), ARLTS1 is strongly down-regulated due to DNA methylation in its promoter region. After ARLTS1 restoration by adenoviral transduction, only the negative TOV-112 and the homozygously mutated (MUT) MCF7 cells, but not the OV-90 cells expressing a normal ARLTS1 product, underwent apoptosis and inhibition of cell growth. Furthermore, ARLTS1 reexpression significantly reduced the tumorigenic potential of TOV-112 in nude mice. On the contrary, the ARLTS1-MUT induced significantly lower levels of apoptosis in infected cells and reduced in vivo tumorigenesis only partially, supporting the hypothesis that Trp149Stop polymorphism is retained in the general population and predisposes to cancer because of a reduction, but not full loss, of normal ARLTS1 function.

CpG methylation in the Fhit regulatory region: relation to Fhit expression in murine tumors.

To determine if: (1) 5′ CpG island methylation is related to Fhit inactivation; (2) there are tumor or carcinogen-specific methylation patterns, we examined 35 CpG sites in the promoter, exon and intron 1 of the mouse Fhit gene. In primary tumors of lung, urinary bladder and tongue, induced by different carcinogens, 15–35% of sites were methylated, with specific methylation patterns associated with each cancer type, suggesting cancer- or tissue-specific methylation patterns. The methylation patterns were associated with reduced Fhit expression, as determined by immunohistochemical analyses. Methylation of rat Fhit 5′ CpGs in mammary adenocarcinomas, detected by methylation specific PCR amplification, also correlated with reduced gene expression. Thus, there was an overall association between promoter/exon 1 methylation and decreased Fhit expression. In contrast, in cancer-derived cell lines 70–95% of the CpG sites were methylated. This is the first detailed study of the relationship between Fhit 5′ CpG island methylation and Fhit expression in murine tumors, our main models for preclinical cancer studies, and provides evidence that loss of Fhit expression and methylation are correlated in these mouse models and these models will be useful to examine the complex relationships among gene expression, methylation patterns and organ specificity.

Patau syndrome with a long survival (146 months): a clinical report and review of literature.

Trisomy 13 is a clinically severe condition first described by Patau in 1960 [Smith et al., 1960]. The frequency of this syndrome is 1:3,000 live births [Tunca et al., 2001]. It is the third most frequent trisomy among live births [Phatak et al., 2004] after trisomy 21 (Down syndrome) and trisomy 18 (Edwards syndrome). Eighty-five percent of liveborns do not survive beyond 1 year of life, and most die before the age of 6 months [Duarte et al., 2004]. Trisomy 13 is characterized by multiple malformations of the cardiac, central nervous, and urogenital systems [Phatak et al., 2004]. There have only been five cases of patients with trisomy 13 previously reported, who had survived past the first decade [Redheendran et al., 1981; Singh, 1990; Zoll et al., 1993; Tunca et al., 2001]. In this report, we present a newborn with trisomy 13, the fourth longest described in the literature and the longest survival (146 months) reported in Greece. A girl, 2.5 years old (birthday: 12/19/1990) was admitted to the 2nd Department of Pediatrics at A.H.E.P.A University Hospital due to multiple anomalies. It was the first child of healthy parents. The mother was 25 years old and unrelated to the father who was 31 years old. The gestation was normal and birth weight was 2,540 g. The patient had microphthalmia, colobomata, cataracts, and ocular hypertelorism. Other findings included abnormal low-set ears, dysplastic auricles, small chin, protruding lower lip, omphalocele, and malformation of the legs. It is interesting that characteristics such as cleft lip or palate, polydactyly or cutis aplasia were absent although they are present in 80% of patients with the syndrome [Redheendran et al., 1981]. In addition she did not have congenital heart defects, renal malformations, but had limb and genital anomalies. Furthermore, the absence in our patient, of common cardiac defects, such as ventricular or atrial septal defects and dextrocardia, were likely related to the long survival. The patient could hardly sit without support and was not able to maintain herself in a sitting position. She was not able to hold objects or speak but sometimes fixed her sight toward objects or sounds that interested her. During clinical examination, pneumonia of the right lobe was diagnosed and treatment with antibiotics was started. Due to multiple malformations, karyotype analysis was performed. Specifically, chromosomal analysis was performed from peripheral blood samples using standard procedures [Iliopoulos et al., 2004]. Twenty GTG (Giemsa)banded metaphases from PHA (phytohemagglutinin)-stimulated peripheral blood lymphocytes demonstrated a karyotype of 47,XX,þ13. After 10 days, she was discharged after improvement of respiratory problems. The infant was re-admitted in our clinic after 9 years, due to initiationof hermenstrual cycle. Clinical examination revealed multiple fractures, chronic respiratory problems, early puberty (8.5 years old), and psychomotor retardation. Due to the very long survival, we decided to repeat the karyotype analysis. Magenis et al. [1968] proposed longer survival of patientswithmosaicism or a Robertsonian translocation in comparison to those with typical trisomy 13, and for this reason we studied 120 metaphases in order to exclude the possibility of mosaicism. However, the chromosomal analysis revealed the same karyotype as previously. The child died in February 2003 at the age of 12 years and 2 months (146 months). It iswell known that trisomy13 and trisomy18have increased infant mortality, but there are very few

Hypermethylation patterns in the Fhit regulatory region are tissue specific

DNA hypermethylation is associated with decreased expression of tumor suppressor genes. We previously observed decreased Fhit expression and Fhit promoter region hypermethylation in rodent tumors induced by various carcinogens, and noted that the 5′ regulatory regions in the promoter, exon 1, and intron 1 were differentially methylated, depending on the tissue of origin. Because different carcinogens were used for induction of tumors of the different organs, we could not conclude that the methylation patterns were tissue‐specific. To determine if in rat tissues: (1) Fhit methylation status is related to expression levels and (2) Fhit methylation patterns were tissue‐ or carcinogen‐specific, we examined Fhit methylation status and expression levels in DMBA‐ and MNU‐induced benign and malignant mammary tumors. Fhit intron 1 was methylated in 3/9 DMBA and all of MNU‐induced benign mammary tumors, in association with reduced Fhit expression levels; Fhit promoter and intron 1 were methylated in all DMBA and MNU‐induced carcinomas in association with highly reduced Fhit expression levels. Treatment of rat cancer cells in vitro with the DNA methyltransferase inhibitor, 5′‐Aza‐2′deoxycytidine, for 4 d, increased Fhit expression and altered the methylation status. Before treatment, both promoter and intron 1 regions were methylated; after treatment, only intron 1 remained methylated. Thus, in carcinogen‐exposed rat tissues there is an overall association of Fhit expression with regulatory region methylation, and hypermethylation patterns did not vary with carcinogen. The specific patterns of hypermethylated CpGs in the Fhit regulatory regions thus appear to be tissue‐specific. Published 2005 Wiley‐Liss, Inc.