Carlo M. Croce

Bio: Carlo M. Croce is an academic researcher from Ohio State University. The author has contributed to research in topics: microRNA & Cancer. The author has an hindex of 198, co-authored 1135 publications receiving 189007 citations. Previous affiliations of Carlo M. Croce include University of Nebraska Medical Center & University of California, Los Angeles.

Reactivation of silent rRNA genes by simian virus 40 in human-mouse hybrid cells

Abstract: Mouse-human hybrid cells were used to study the ability of simian virus 40 to regulate the expression of rRNA genes in vivo. In these hybrid cells, only the rRNA genes of the dominant species are expressed; the genes for the rRNA of the recessive species are silent. Simian virus 40 infection of these hybrids led to the production of two distinct 28S rRNA species as analyzed by agarose/2.4% polyacrylamide gel electrophoresis. These species were identified as human and mouse rRNAs. This result was confirmed by histochemical studies which indicated that the nucleolus organizer regions of both mouse and human chromosomes were actively synthesizing rRNA in the virus-infected hybrid cells. These results indicate that simian virus 40 infection can induce the expression of otherwise silent rRNA genes.

Aberrant FHIT Transcripts in Merkel Cell Carcinoma

Abstract: Merkel cell carcinoma is a rare neuroendocrine carcinoma of the skin which shares several features with small cell lung carcinoma. In a previous study, we reported a high frequency of abnormalities of the FHIT gene, located at 3p14.2, in small cell lung tumors. To determine the role of the FHIT gene in small cell neuroendocrine malignancies, 14 cases of Merkel cell carcinoma were analyzed by reverse transcription of FHIT mRNA followed by PCR amplification and sequencing of products. Eight of 14 tumors (57%) displayed abnormal FHIT products that lacked three or more exons of the FHIT gene. The pattern of abnormal transcripts was similar to that observed in small cell lung tumors, suggesting that FHIT abnormalities might be a common genetic marker of these two types of neuroendocrine tumors.

Sequence conservation at human and mouse orthologous common fragile regions, FRA3B/FHIT and Fra14A2/Fhit

Abstract: It has been suggested that delayed DNA replication underlies fragility at common human fragile sites, but specific sequences responsible for expression of these inducible fragile sites have not been identified. One approach to identify such cis-acting sequences within the large nonexonic regions of fragile sites would be to identify conserved functional elements within orthologous fragile sites by interspecies sequence comparison. This study describes a comparison of orthologous fragile regions, the human FRA3B / FHIT and the murine Fra14A2 / Fhit locus. We sequenced over 600 kbp of the mouse Fra14A2 , covering the region orthologous to the fragile epicenter of FRA3B , and determined the Fhit deletion break points in a mouse kidney cancer cell line (RENCA). The murine Fra14A2 locus, like the human FRA3B , was characterized by a high AT content. Alignment of the two sequences showed that this fragile region was stable in evolution despite its susceptibility to mitotic recombination on inhibition of DNA replication. There were also several unusual highly conserved regions (HCRs). The positions of predicted matrix attachment regions (MARs), possibly related to replication origins, were not conserved. Of known fragile region landmarks, five cancer cell break points, one viral integration site, and one aphidicolin break cluster were located within or near HCRs. Thus, comparison of orthologous fragile regions has identified highly conserved sequences with possible functional roles in maintenance of fragility.

Cytogenetic and Interphase Cytogenetic Characterization of Atypical Chronic Lymphocytic Leukemia Carrying BCL1 Translocation

Abstract: Conventional chromosome analysis (CCA) and fluorescent in situ hybridization (FISH) studies, using a 390-kb yeast artificial chromosome probe spanning the area of multiple breakpoints of the BCL1 locus at 11q13, were performed on 57 patients fulfilling the French-American-British criteria for the diagnosis of atypical B-cell chronic lymphocytic leukemia (CLL). To better define the incidence of 13q deletions and trisomy 12, FISH analysis was also performed using a cosmid probe that recognized a DNA sequence between the Rb gene and the D13S25 locus at band 13q14 and a chromosome 12-specific pericentromeric probe. All patients were characterized by cytoimmunological and hematological studies. Fourteen cases displayed three fluorescent signals in 41–98% interphase cells when hybridized to the BCL1 yeast artificial chromosome probe, documenting the presence of BCL1 translocation (BCL1-positive cases). The presence of t(11;14)(q13;q32) was ascertained in 12 cases using CCA and by dual color interphase FISH using the BCL1 probe and a 14q telomere probe in 2 karyotypically normal cases. The remaining 43 cases had two signals in more than 95% interphase cells (BCL1-negative) and did not have the t(11;14) at CCA. Although 13q14 deletions were seen by means of CCA in only 5 of 14 BCL1-positive cases, hemizygous or homozygous deletions at band 13q14 were detected by FISH in 11 of 14 BCL1-positive cases, as compared with 17 of 43 BCL1-negative cases (P = 0.01). A subclone with trisomy 12 in addition to BCL1 translocation and del(13q14) was present in four BCL1-positive cases. We arrived at the following conclusions: (a) FISH with this BCL1 YAC probe is an efficient method for the detection of the t(11;14) and of the corresponding involvement of the BCL1 locus in this lymphoproliferative disorder; (b) the majority of BCL1-positive atypical CLLs by French-American-British criteria may carry 13q14 deletions; (c) the recognition of this cytogenetic subset of atypical CLL, sharing some immunological and cytogenetic features with mantle cell lymphoma, may be important, because these patients usually present isolated peripheral blood and marrow lymphocytosis, with or without mild to moderate spleen involvement, and may require early cytotoxic treatment.

Pharmacological targeting of miR-155 via the NEDD8-activating enzyme inhibitor MLN4924 (Pevonedistat) in FLT3 -ITD acute myeloid leukemia

Abstract: High levels of microRNA-155 (miR-155) are associated with poor outcome in acute myeloid leukemia (AML). In AML, miR-155 is regulated by NF-κB, the activity of which is, in part, controlled by the NEDD8-dependent ubiquitin ligases. We demonstrate that MLN4924, an inhibitor of NEDD8-activating enzyme presently being evaluated in clinical trials, decreases binding of NF-κB to the miR-155 promoter and downregulates miR-155 in AML cells. This results in the upregulation of the miR-155 targets SHIP1, an inhibitor of the PI3K/Akt pathway, and PU.1, a transcription factor important for myeloid differentiation, leading to monocytic differentiation and apoptosis. Consistent with these results, overexpression of miR-155 diminishes MLN4924-induced antileukemic effects. In vivo, MLN4924 reduces miR-155 expression and prolongs the survival of mice engrafted with leukemic cells. Our study demonstrates the potential of miR-155 as a novel therapeutic target in AML via pharmacologic interference with NF-κB-dependent regulatory mechanisms. We show the targeting of this oncogenic microRNA with MLN4924, a compound presently being evaluated in clinical trials in AML. As high miR-155 levels have been consistently associated with aggressive clinical phenotypes, our work opens new avenues for microRNA-targeting therapeutic approaches to leukemia and cancer patients.

Gapped BLAST and PSI-BLAST: a new generation of protein database search programs.

Abstract: The BLAST programs are widely used tools for searching protein and DNA databases for sequence similarities. For protein comparisons, a variety of definitional, algorithmic and statistical refinements described here permits the execution time of the BLAST programs to be decreased substantially while enhancing their sensitivity to weak similarities. A new criterion for triggering the extension of word hits, combined with a new heuristic for generating gapped alignments, yields a gapped BLAST program that runs at approximately three times the speed of the original. In addition, a method is introduced for automatically combining statistically significant alignments produced by BLAST into a position-specific score matrix, and searching the database using this matrix. The resulting Position-Specific Iterated BLAST (PSIBLAST) program runs at approximately the same speed per iteration as gapped BLAST, but in many cases is much more sensitive to weak but biologically relevant sequence similarities. PSI-BLAST is used to uncover several new and interesting members of the BRCT superfamily.

Analyzing real-time PCR data by the comparative C(T) method.

Abstract: Two different methods of presenting quantitative gene expression exist: absolute and relative quantification. Absolute quantification calculates the copy number of the gene usually by relating the PCR signal to a standard curve. Relative gene expression presents the data of the gene of interest relative to some calibrator or internal control gene. A widely used method to present relative gene expression is the comparative C(T) method also referred to as the 2 (-DeltaDeltaC(T)) method. This protocol provides an overview of the comparative C(T) method for quantitative gene expression studies. Also presented here are various examples to present quantitative gene expression data using this method.

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。