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Dive into the research topics where Alexandru Olaru is active.

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Featured researches published by Alexandru Olaru.


Hepatology | 2009

MicroRNA-21 is overexpressed in human cholangiocarcinoma and regulates programmed cell death 4 and tissue inhibitor of metalloproteinase 3†

Florin M. Selaru; Alexandru Olaru; Takatsugu Kan; Stefan David; Yulan Cheng; Yuriko Mori; Jian Yang; Bogdan C. Paun; Zhe Jin; Rachana Agarwal; James P. Hamilton; John A. Abraham; Christos S. Georgiades; Hector Alvarez; Perumal Vivekanandan; Wayne Yu; Anirban Maitra; Michael Torbenson; Paul J. Thuluvath; Gregory J. Gores; Nicholas F. LaRusso; Ralph H. Hruban; Stephen J. Meltzer

Cholangiocarcinomas (CCAs) are aggressive cancers, with high mortality and poor survival rates. Only radical surgery offers patients some hope of cure; however, most patients are not surgical candidates because of late diagnosis secondary to relatively poor accuracy of diagnostic means. MicroRNAs (miRs) are involved in every cancer examined, but they have not been evaluated in primary CCA. In this study, miR arrays were performed on five primary CCAs and five normal bile duct specimens (NBDs). Several miRs were dysregulated and miR‐21 was overexpressed in CCAs. miR‐21 differential expression in these 10 specimens was verified by quantitative reverse transcriptase polymerase chain reaction (qRT‐PCR). To validate these findings, qRT‐PCR for miR‐21 was then performed on 18 additional primary CCAs and 12 normal liver specimens. MiR‐21 was 95% sensitive and 100% specific in distinguishing between CCA and normal tissues, with an area under the receiver operating characteristic curve of 0.995. Inhibitors of miR‐21 increased protein levels of programmed cell death 4 (PDCD4) and tissue inhibitor of metalloproteinases 3 (TIMP3). Notably, messenger RNA levels of TIMP3 were significantly lower in CCAs than in normals. Conclusions: MiR‐21 is overexpressed in human CCAs. Furthermore, miR‐21 may be oncogenic, at least in part, by inhibiting PDCD4 and TIMP3. Finally, these data suggest that TIMP3 is a candidate tumor suppressor gene in the biliary tree. (HEPATOLOGY 2009.)


Cancer Research | 2009

A multicenter, double-blinded validation study of methylation biomarkers for progression prediction in Barrett’s esophagus

Zhe Jin; Yulan Cheng; Wen Gu; Yingye Zheng; Fumiaki Sato; Yuriko Mori; Alexandru Olaru; Bogdan C. Paun; Jian Yang; Takatsugu Kan; Tetsuo Ito; James P. Hamilton; Florin M. Selaru; Rachana Agarwal; Stefan David; John M. Abraham; Herbert C. Wolfsen; Michael B. Wallace; Nicholas J. Shaheen; Kay Washington; Jean Q Wang; Marcia I. Canto; Achyut K. Bhattacharyya; Mark A. Nelson; Paul A. Wagner; Yvonne Romero; Kenneth K. Wang; Ziding Feng; Richard E. Sampliner; Stephen J. Meltzer

Esophageal adenocarcinoma risk in Barretts esophagus (BE) is increased 30- to 125-fold versus the general population. Among all BE patients, however, neoplastic progression occurs only once per 200 patient-years. Molecular biomarkers are therefore needed to risk-stratify patients for more efficient surveillance endoscopy and to improve the early detection of progression. We therefore performed a retrospective, multicenter, double-blinded validation study of eight BE progression prediction methylation biomarkers. Progression or nonprogression were determined at 2 years (tier 1) and 4 years (tier 2). Methylation was assayed in 145 nonprogressors and 50 progressors using real-time quantitative methylation-specific PCR. Progressors were significantly older than nonprogressors (70.6 versus 62.5 years; P < 0.001). We evaluated a linear combination of the eight markers, using coefficients from a multivariate logistic regression analysis. Areas under the ROC curve (AUC) were high in the 2-year, 4-year, and combined data models (0.843, 0.829, and 0.840; P < 0.001, <0.001, and <0.001, respectively). In addition, even after rigorous overfitting correction, the incremental AUCs contributed by panels based on the 8 markers plus age versus age alone were substantial (Delta-AUC = 0.152, 0.114, and 0.118, respectively) in all 3 models. A methylation biomarker-based panel to predict neoplastic progression in BE has potential clinical value in improving both the efficiency of surveillance endoscopy and the early detection of neoplasia.


Inflammatory Bowel Diseases | 2011

Dynamic changes in the expression of microRNA-31 during inflammatory bowel disease-associated neoplastic transformation

Alexandru Olaru; Florin M. Selaru; Yuriko Mori; Christine Vazquez; Stefan David; Bogdan C. Paun; Yulan Cheng; Zhe Jin; Jian Yang; Rachana Agarwal; John M. Abraham; Themistocles Dassopoulos; Mary L. Harris; Theodore M. Bayless; John H. Kwon; Noam Harpaz; Ferenc Livak; Stephen J. Meltzer

Background: Patients with inflammatory bowel disease (IBD) are at increased risk of developing colorectal cancer. Aberrant microRNA (miR) expression has been linked to carcinogenesis; however, no reports document a relationship between IBD‐related neoplasia (IBDN) and altered miR expression. In the current study we sought to identify specific miR dysregulation along the normal–inflammation–cancer axis. Methods: miR microarrays and quantitative reverse‐transcriptase polymerase chain reaction (RT‐PCR) were used to detect dysregulated miRs. Receiver operating characteristic curve analysis was employed to test for potential usefulness of miR‐31 as a disease marker of IBDNs. In silico prediction analysis, Western blot, and luciferase activity measurement were employed for target identification. Results: Several dysregulated miRs were identified between chronically inflamed mucosae and dysplasia arising in IBD. MiR‐31 expression increases in a stepwise fashion during progression from normal to IBD to IBDN and accurately discriminated IBDNs from normal or chronically inflamed tissues in IBD patients. Finally, we identified factor inhibiting hypoxia inducible factor 1 as a direct target of miR‐31. Conclusions: Our study reveals specific miR dysregulation as chronic inflammation progresses to dysplasia. MiR‐31 expression levels increase with disease progression and accurately discriminates between distinct pathological entities that coexist in IBD patients. The novel effect of miR‐31 on regulating factor inhibiting hypoxia inducible factor 1 expression provides a new insight on the pathogenesis of IBDN. (Inflamm Bowel Dis 2011;)


Oncogene | 2011

MicroRNA-192 and -215 are upregulated in human gastric cancer in vivo and suppress ALCAM expression in vitro.

Zhe Jin; Florin M. Selaru; Yulan Cheng; Takatsugu Kan; Rachana Agarwal; Yuriko Mori; Alexandru Olaru; Jr Ming Yang; Stefan David; James P. Hamilton; John M. Abraham; J Harmon; M Duncan; Elizabeth A. Montgomery; Stephen J. Meltzer

The dismal outcome of gastric cancer patients highlights the need for diagnostic biomarkers and effective therapeutic targets, such as microRNAs. We sought to discover microRNAs involved in gastric cancer, and to elucidate their downstream target mechanisms. Both cultured gastric epithelial cells (HFE145 and NCI-N87) and primary human gastric tissues (31 non-neoplastic stomach (NS) and 25 gastric carcinomas (GC)) were studied. MicroRNA microarrays and quantitative RT–PCR were applied to discover and verify differentially expressed microRNAs. in vitro cell migration and invasion, cell proliferation, cell cycle and apoptosis assays were executed to elucidate biological effects of microRNA-192 and -215. Western blotting and luciferase assays were performed to confirm direct messenger RNA targeting by microRNA-192 and -215. MicroRNA microarray analyses revealed that 25 and 20 microRNAs were upregulated and downregulated in GC vs NS, respectively. Expression levels of both microRNA-192 and -215 were significantly higher in GC than in NS (P<0.05). Luciferase assays suggested that microRNA-215 inhibits activated leukocyte cell adhesion molecule (ALCAM) expression at the posttranscriptional level. In addition, expression levels of ALCAM were significantly lower in GC than in NS. Mimics and inhibitors, respectively, of microRNA-192 or -215 exerted no effect on cell cycle or apoptosis in the immortalized normal gastric cell line HFE145 or the gastric cancer cell line NCI-N87. However, mimics of microRNA-192 or -215 significantly increased growth rates in HFE145 cells, whereas inhibitors of microRNA-192 or -215 caused significant decreases in growth rates in NCI-N87 cells. ALCAM knockdown by an ALCAM-specific siRNA significantly increased cell growth in HFE145 cells. Both transfection of mimics of microRNA-192 or -215 and ALCAM knockdown by an ALCAM-specific siRNA significantly increased the migration of HFE145 cells. In conclusion, in gastric cancer, both microRNA-192 and -215 are overexpressed in vivo and exert cell growth and migration-promoting effects in vitro, thus representing potential microRNAs with a role in cancer in the human stomach.


Hepatology | 2011

MicroRNA down-regulated in human cholangiocarcinoma control cell cycle through multiple targets involved in the G1/S checkpoint

Alexandru Olaru; Gabriel Ghiaur; Sumitaka Yamanaka; Delgermaa Luvsanjav; Fangmei An; Irinel Popescu; Sorin Alexandrescu; Sarah E Allen; Timothy M. Pawlik; Michael Torbenson; Christos S. Georgiades; Lewis R. Roberts; Gregory J. Gores; Anne C. Ferguson-Smith; Maria Inês Almeida; George A. Calin; Esteban Mezey; Florin M. Selaru

MicroRNAs (miRs) recently emerged as prominent regulators of cancer processes. In the current study we aimed at elucidating regulatory pathways and mechanisms through which miR‐494, one of the miR species found to be down‐regulated in cholangiocarcinoma (CCA), participates in cancer homeostasis. miR‐494 was identified as down‐regulated in CCA based on miR arrays. Its expression was verified with quantitative real‐time reverse‐transcription polymerase chain reaction (qRT‐PCR). To enforce miR expression, we employed both transfection methods, as well as a retroviral construct to stably overexpress miR‐494. Up‐regulation of miR‐494 in cancer cells decreased growth, consistent with a functional role. mRNA arrays of cells treated with miR‐494, followed by pathway analysis, suggested that miR‐494 impacts cell cycle regulation. Cell cycle analyses demonstrated that miR‐494 induces a significant G1/S checkpoint reinforcement. Further analyses demonstrated that miR‐494 down‐regulates multiple molecules involved in this transition checkpoint. Luciferase reporter assays demonstrated a direct interaction between miR‐494 and the 3′‐untranslated region of cyclin‐dependent kinase 6 (CDK6). Last, xenograft experiments demonstrated that miR‐494 induces a significant cancer growth retardation in vivo. Conclusion: Our findings demonstrate that miR‐494 is down‐regulated in CCA and that its up‐regulation induces cancer cell growth retardation through multiple targets involved in the G1‐S transition. These findings support the paradigm that miRs are salient cellular signaling pathway modulators, and thus represent attractive therapeutic targets. miR‐494 emerges as an important regulator of CCA growth and its further study may lead to the development of novel therapeutics. (HEPATOLOGY 2011)


Clinical Cancer Research | 2007

Hypermethylation of tachykinin-1 is a potential biomarker in human esophageal cancer.

Zhe Jin; Alexandru Olaru; Jian Yang; Fumiaki Sato; Yulan Cheng; Takatsugu Kan; Yuriko Mori; Carmit Mantzur; Bogdan C. Paun; James P. Hamilton; Tetsuo Ito; Suna Wang; Stefan David; Rachana Agarwal; David G. Beer; John M. Abraham; Stephen J. Meltzer

Purpose: Our aim was to investigate whether and at what stage hypermethylation of the tachykinin-1 (TAC1) gene is associated with human esophageal neoplastic transformation. Experimental Design:TAC1 promoter hypermethylation was examined by real-time methylation-specific PCR in 258 human esophageal specimens and 126 plasma samples from patients or tissues at various stages of neoplastic evolution. Results:TAC1 hypermethylation in tissue samples showed highly discriminative receiver-operator characteristic curve profiles, clearly distinguishing esophageal squamous cell carcinoma (ESCC) and esophageal adenocarcinoma (EAC) from normal esophagus (P < 0.0001). Both frequencies and normalized methylation values of TAC1 tissue methylation were significantly higher in Barretts metaplasia (BE), dysplastic Barretts esophagus, EAC, and ESCC than in normal esophagus (P < 0.01). The frequency of TAC1 hypermethylation increased dramatically and early during neoplastic progression, from 7.5% in normal esophagus to 55.6% in BE from patients with Barretts metaplasia alone, 57.5% in dysplastic Barretts esophagus, and 61.2% in EAC. There was a significant relationship between TAC1 hypermethylation and BE segment length, a known clinical risk factor for neoplastic progression. Twelve (50%) of 24 ESCC exhibited TAC1 hypermethylation. Overall patient survival correlated significantly with TAC1 methylation status in ESCC patients (mean survival, 22 versus 110 months; P = 0.0102, log-rank test), but not in EAC patients. Both mean normalized methylation values and frequency of TAC1 hypermethylation in plasma samples were significantly higher in EAC patients than in control subjects. Treatment of KYSE220 ESCC and BIC EAC cells with 5-aza-2′-deoxycytidine reduced TAC1 methylation and increased TAC1 mRNA expression. Conclusions:TAC1 promoter hypermethylation is a common event in both major histologic types of human esophageal carcinoma, occurs early, correlates with other progression risk factors in esophageal adenocarcinogenesis, and is a tissue biomarker of a poor prognosis in ESCC. Circulating methylated TAC1 promoter DNA also offers potential as a biomarker for the diagnosis of EAC.


PLOS ONE | 2009

Silencing of Claudin-11 Is Associated with Increased Invasiveness of Gastric Cancer Cells

Rachana Agarwal; Yuriko Mori; Yulan Cheng; Zhe Jin; Alexandru Olaru; James P. Hamilton; Stefan David; Florin M. Selaru; Jian Yang; John M. Abraham; Elizabeth A. Montgomery; Patrice J. Morin; Stephen J. Meltzer

Background Claudins are membrane proteins that play critical roles in tight junction (TJ) formation and function. Members of the claudin gene family have been demonstrated to be aberrantly regulated, and to participate in the pathogenesis of various human cancers. In the present study, we report that claudin-11 (CLDN11) is silenced in gastric cancer via hypermethylation of its promoter region. Methodology/Principal Findings Levels of CLDN11 methylation and mRNA expression were measured in primary gastric cancer tissues, noncancerous gastric mucosae, and cell lines of gastric origin using quantitative methylation-specific PCR (qMSP) and quantitative reverse transcriptase-PCR (qRT-PCR), respectively. Analyses of paired gastric cancers and adjacent normal gastric tissues revealed hypermethylation of the CLDN11 promoter region in gastric cancers, and this hypermethylation was significantly correlated with downregulation of CLDN11 expression vs. normal tissues. The CLDN11 promoter region was also hypermethylated in all gastric cancer cell lines tested relative to immortalized normal gastric epithelial cells. Moreover, CLDN11 mRNA expression was inversely correlated with its methylation level. Treatment of CLDN11-nonexpressing gastric cancer cells with 5-aza-2′-deoxycytidine restored CLDN11 expression. Moreover, siRNA-mediated knockdown of CLDN11 expression in normal gastric epithelial cells increased their motility and invasiveness. Conclusions/Significance These data suggest that hypermethylation of CLDN11, leading to downregulated expression, contributes to gastric carcinogenesis by increasing cellular motility and invasiveness. A further understanding of the mechanisms underlying the role of claudin proteins in gastric carcinogenesis will likely help in the identification of novel approaches for diagnosis and therapy of gastric cancer.


PLOS ONE | 2008

Three-tiered risk stratification model to predict progression in Barrett's esophagus using epigenetic and clinical features

Fumiaki Sato; Zhe Jin; Karsten Schulmann; Jean Wang; Bruce D. Greenwald; Tetsuo Ito; Takatsugu Kan; James P. Hamilton; Jian Yang; Bogdan C. Paun; Stefan David; Alexandru Olaru; Yulan Cheng; Yuriko Mori; John M. Abraham; Harris G. Yfantis; Tsung Teh Wu; Mary Fredericksen; Kenneth K. Wang; Marcia I. Canto; Yvonne Romero; Ziding Feng; Stephen J. Meltzer

Background Barretts esophagus predisposes to esophageal adenocarcinoma. However, the value of endoscopic surveillance in Barretts esophagus has been debated because of the low incidence of esophageal adenocarcinoma in Barretts esophagus. Moreover, high inter-observer and sampling-dependent variation in the histologic staging of dysplasia make clinical risk assessment problematic. In this study, we developed a 3-tiered risk stratification strategy, based on systematically selected epigenetic and clinical parameters, to improve Barretts esophagus surveillance efficiency. Methods and Findings We defined high-grade dysplasia as endpoint of progression, and Barretts esophagus progressor patients as Barretts esophagus patients with either no dysplasia or low-grade dysplasia who later developed high-grade dysplasia or esophageal adenocarcinoma. We analyzed 4 epigenetic and 3 clinical parameters in 118 Barretts esophagus tissues obtained from 35 progressor and 27 non-progressor Barretts esophagus patients from Baltimore Veterans Affairs Maryland Health Care Systems and Mayo Clinic. Based on 2-year and 4-year prediction models using linear discriminant analysis (area under the receiver-operator characteristic (ROC) curve: 0.8386 and 0.7910, respectively), Barretts esophagus specimens were stratified into high-risk (HR), intermediate-risk (IR), or low-risk (LR) groups. This 3-tiered stratification method retained both the high specificity of the 2-year model and the high sensitivity of the 4-year model. Progression-free survivals differed significantly among the 3 risk groups, with p = 0.0022 (HR vs. IR) and p<0.0001 (HR or IR vs. LR). Incremental value analyses demonstrated that the number of methylated genes contributed most influentially to prediction accuracy. Conclusions This 3-tiered risk stratification strategy has the potential to exert a profound impact on Barretts esophagus surveillance accuracy and efficiency.


Oncogene | 2007

Hypermethylation of the nel-like 1 gene is a common and early event and is associated with poor prognosis in early-stage esophageal adenocarcinoma

Zhe Jin; Yuriko Mori; Jr Ming Yang; Fumiaki Sato; Tetsuo Ito; Yulan Cheng; Bogdan C. Paun; James P. Hamilton; Takatsugu Kan; Alexandru Olaru; Stefan David; Rachana Agarwal; John M. Abraham; David G. Beer; Elizabeth A. Montgomery; Stephen J. Meltzer

The nel-like1 (NELL1) gene maps to chromosome 11p15, which frequently undergoes loss of heterozygosity in esophageal adenocarcinoma (EAC). NELL1 promoter hypermethylation was examined by real-time methylation-specific polymerase chain reaction in 259 human esophageal tissues. Hypermethylation of this promoter showed highly discriminative receiver–operator characteristic curve profiles, clearly distinguishing esophageal squamous cell carcinoma (ESCC) and EAC from normal esophagus (NE) (P<0.001). NELL1 normalized methylation values were significantly higher in Barretts metaplasia (BE), dysplastic Barretts (D) and EAC than in NE (P<0.0000001). NELL1 hypermethylation frequency was zero in NE but increased early during neoplastic progression, to 41.7% in BE from patients with Barretts alone, 52.5% in D and 47.8% in EAC. There was a significant correlation between NELL1 hypermethylation and BE segment length. Three (11.5%) of 26 ESCCs exhibited NELL1 hypermethylation. Survival correlated inversely with NELL1 hypermethylation in patients with stages I–II (P=0.0264) but not in stages III–IV (P=0.68) EAC. Treatment of KYSE220 ESCC and BIC EAC cells with 5-aza-2′-deoxycytidine reduced NELL1 methylation and increased NELL1 mRNA expression. NELL1 mRNA levels in EACs with an unmethylated NELL1 promoter were significantly higher than those in EACs with a methylated promoter (P=0.02). Promoter hypermethylation of NELL1 is a common, tissue-specific event in human EAC, occurs early during Barretts-associated esophageal neoplastic progression, and is a potential biomarker of poor prognosis in early-stage EAC.


Endocrine-related Cancer | 2011

Novel Candidate Colorectal Cancer Biomarkers Identified by Methylation Microarray-Based Scanning

Yuriko Mori; Alexandru Olaru; Yulan Cheng; Rachana Agarwal; Jian Yang; Delgermaa Luvsanjav; Wayne Yu; Florin M. Selaru; Susan Hutfless; Mark Lazarev; John H. Kwon; Steven R. Brant; Michael R Marohn; David F. Hutcheon; Mark D. Duncan; Ajay Goel; Stephen J. Meltzer

DNA hypermethylation is a common epigenetic abnormality in colorectal cancers (CRCs) and a promising class of CRC screening biomarkers. We conducted a genome-wide search for novel neoplasia-specific hypermethylation events in the colon. We applied methylation microarray analysis to identify loci hypermethylated in 17 primary CRCs relative to eight non-neoplastic colonic mucosae (NCs) from neoplasia-free subjects. These CRC-associated hypermethylation events were then individually evaluated for their ability to discriminate neoplastic from non-neoplastic cases, based on real-time quantitative methylation-specific PCR (qMSP) assays in 113 colonic tissues: 51 CRCs, nine adenomas, 19 NCs from CRC patients (CRC-NCs), and 34 NCs from neoplasia-free subjects (control NCs). A strict microarray data filtering identified 169 candidate CRC-associated hypermethylation events. Fourteen of these 169 loci were evaluated using qMSP assays. Ten of these 14 methylation events significantly distinguished CRCs from age-matched control NCs (P<0.05 by receiver operator characteristic curve analysis); methylation of visual system homeobox 2 (VSX2) achieved the highest discriminative accuracy (83.3% sensitivity and 92.3% specificity, P<1×10(-6)), followed by BEN domain containing 4 (BEND4), neuronal pentraxin I (NPTX1), ALX homeobox 3 (ALX3), miR-34b, glucagon-like peptide 1 receptor (GLP1R), BTG4, homer homolog 2 (HOMER2), zinc finger protein 583 (ZNF583), and gap junction protein, gamma 1 (GJC1). Adenomas were significantly discriminated from control NCs by hypermethylation of VSX2, BEND4, NPTX1, miR-34b, GLP1R, and HOMER2 (P<0.05). CRC-NCs were significantly distinguished from control NCs by methylation of ALX3 (P<1×10(-4)). In conclusion, systematic methylome-wide analysis has identified ten novel methylation events in neoplastic and non-neoplastic colonic mucosae from CRC patients. These potential biomarkers significantly discriminate CRC patients from controls. Thus, they merit further evaluation in stool- and circulating DNA-based CRC detection studies.

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Stephen J. Meltzer

Johns Hopkins University School of Medicine

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Yuriko Mori

Johns Hopkins University

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Yulan Cheng

Johns Hopkins University School of Medicine

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Stefan David

Johns Hopkins University

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Zhe Jin

Johns Hopkins University

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John M. Abraham

Johns Hopkins University School of Medicine

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Jian Yang

Johns Hopkins University

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James P. Hamilton

Johns Hopkins University School of Medicine

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