Takis S. Papas

Hemorrhage, impaired hematopoiesis, and lethality in mouse embryos carrying a targeted disruption of the Fli1 transcription factor.

ABSTRACT The Ets family of transcription factors have been suggested to function as key regulators of hematopoeisis. Here we describe aberrant hematopoeisis and hemorrhaging in mouse embryos homozygous for a targeted disruption in the Ets family member, Fli1. Mutant embryos are found to hemorrhage from the dorsal aorta to the lumen of the neural tube and ventricles of the brain (hematorrhachis) on embryonic day 11.0 (E11.0) and are dead by E12.5. Histological examinations and in situ hybridization reveal disorganization of columnar epithelium and the presence of hematomas within the neuroepithelium and disruption of the basement membrane lying between this and mesenchymal tissues, both of which express Fli1 at the time of hemorrhaging. Livers from mutant embryos contain few pronormoblasts and basophilic normoblasts and have drastically reduced numbers of colony forming cells. These defects occur with complete penetrance of phenotype regardless of the genetic background (inbred B6, hybrid 129/B6, or outbred CD1) or the targeted embryonic stem cell line used for the generation of knockout lines. Taken together, these results provide in vivo evidence for the role of Fli1 in the regulation of hematopoiesis and hemostasis.

Down-regulation of T1A12/mac25, a novel insulin-like growth factor binding protein related gene, is associated with disease progression in breast carcinomas.

To define genes that are essential to the initiation and progression of breast cancer we utilized subtractive hybridization and differential display cloning techniques and isolated over 950 cDNAs from breast cell-lines derived from matched normal and tumor tissue. Of these, 102 cDNAs were characterized by DNA sequencing and Northern blot analysis. GenBank searches showed that one of these genes, T1A12 is identical to mac25, an insulin-like growth factor-binding protein related gene. Antibodies generated against the C-terminal region of the T1A12/mac25 protein were used to investigate its expression in 60 primary breast tissues. Sections of 12 benign, 16 ductal carcinoma in situ and 32 infiltrating ductal carcinoma specimens were examined. Strong immunoperoxidase staining was observed in luminal epithelial cells of normal lobules and ducts, in apocrine cells of cysts and fibroadenomas. Moderate to weak protein expression was found in hyperplastic and DCIS cells, but no specific staining was detected in invasive carcinoma cells. FISH mapping using a PAC clone localized the T1A12/mac25 gene to 4q12-13. Microsatellite length polymorphism was studied using markers for 4q in paired normal and tumor breast tissues. Thirty-three per cent (10/30) of the samples were found to be polymorphic with D4S189 and D4S231 microsatellite markers and LOH was detected in 50% (5/10) of these informative samples. Our data indicate that T1A12/mac25 expression is abrogated during breast cancer progression concomitant with loss of heterozygosity on chromosome 4q. T1A12/mac25 may therefore have a tumor suppressor-like function and its expression could indicate a disease with a more favorable status, having a better prognosis.

A variant form of ETS1 induces apoptosis in human colon cancer cells

We have previously shown that the human ETS1 protein (p51-ETS1), when ectopically expressed in colon cancer cell lines, is able to reduce its tumorigenicity without affecting its growth properties. To understand the mechanism of tumor reduction, we have expressed two different forms of ETS1 in colon cancer cell lines. Data presented in this paper indicate that the naturally occurring spliced variant protein, p42-ETS1, lacking the region encoded by ETS1 exon VII, represses the tumorigenicity, while p51-ETS1 reduces the tumorigenicity. Repression of tumorigenicity mediated by p42-ETS1 appears to be caused by its ability to induce apoptosis in epithelial cancer cells. This work can have profound medical significance in that it may open up new insights into the potential role of the p42-ETS1 in the induction of apoptosis in epithelial cell cancers and may provide a rationale for its use for potential gene therapy experiments to initiate cell death in cancer cells.

Breast cancer genome anatomy: correlation of morphological changes in breast carcinomas with expression of the novel gene product Di12.

To determine which genes may be activated or inactivated during breast cancer development, we employed two cloning strategies (subtractive hybridization and differential display) using RNA samples from a human breast tumor and its matching normal breast cell line. Of 950 clones isolated, 102 cDNA inserts were analysed by DNA sequencing and database searching. We found 30 clones that were obviously unidentified, with no significant homology to any listed human gene. We focused upon one of the novel genes, Di12, that is differentially expressed as a 1.35u2009kb RNA in breast cancer tissues and cell-lines, and in several normal tissues. A full length cDNA of this gene was cloned, and its DNA sequence revealed an open reading frame of 339 amino acids. Antibodies to the ten N-terminal amino acids were developed to investigate the expression of Di12 in breast cancer cell-lines and tumors. The Di12 protein was found in tissue sections of infiltrating ductal carcinomas (IDCs), but not in benign or normal breast specimens. RTu2009–u2009PCR analysis confirmed expression of Di12 in 80% of infiltrating ductal carcinomas (IDCs). As IDC constitutes ∼70% of breast cancers seen clinically, the level of Di12 expression may be predictive of disease progression.

Phosphorylation of the ETS-2 protein: regulation by the T-cell antigen receptor-CD3 complex.

Phosphorylation of the human ets-2 protein in response to mitogenic signals to T lymphocytes was investigated in Jurkat cells. Activation of the cells by antibodies against the T-cell antigen receptor-CD3 complex or by concanavalin A was followed within 5 min by increased phosphorylation of the protein, as shown by a mobility shift of the protein from 54 to 56 kilodaltons in sodium dodecyl sulfate-polyacrylamide gel electrophoresis and increased incorporation of 32P. The Ca2+ ionophores A23187 and ionomycin were able to mimic this effect, suggesting that this phosphorylation is mediated by Ca2+.

c-myc can induce expression of G0/G1 transition genes.

The human c-myc oncogene was linked to the heat shock-inducible Drosophila hsp70 promoter and used to stably transfect mouse BALB/c 3T3 cells. Heat shock of the transfectants at 42 degrees C followed by recovery at 37 degrees C resulted in the appearance of the human c-myc protein which was appropriately localized to the nuclear fraction. Two-dimensional analysis of the proteins of density-arrested cells which had been heat shock treated revealed the induction of eight protein species and the repression of five protein species. All of the induced and repressed proteins were nonabundant. cDNA clones corresponding to genes induced during the G0/G1 transition were used as probes to assay for c-myc inducibility of these genes. Two anonymous sequences previously identified as serum inducible (3CH77 and 3CH92) were induced when c-myc was expressed. In response to serum stimulation, 3CH77 and 3CH92 were expressed before c-myc mRNA levels increased. However, in response to specific induction of c-myc by heat shock of serum arrested cells, 3CH77 and 3CH92 mRNA levels increased after the rise in c-myc mRNA. Therefore, we hypothesize that abnormal expression of c-myc can induce genes involved in the proliferative response.

The S29 ribosomal protein increases tumor suppressor activity of K rev-1 gene on v-K ras-transformed NIH3T3 cells☆

The human S29 ribosomal protein (S29 rp) cDNA has been isolated from differential hybridization screening of a colon carcinoma cDNA library. Northern blot analysis showed that the level of S29 rp mRNA was higher in undifferentiated HT29 human colon carcinoma cells than in a morphologically differentiated subclone under the same growth condition. Furthermore, the level of S29 rp mRNA was downregulated in rapidly proliferating HT29 cells, as compared to the contact inhibited cells. Interestingly, the amount of Krev-1 mRNA was inversely correlated with respect to the amount of S29 rp mRNA in these cells. To examine a functional link between S29 rp and Krev-1 protein, we co-transfected the expression vectors containing wild-type or mutant S29 rp and mutationally activated Krev-1(63E) cDNAs into the v-Ki-ras-transformed NIH3T3 (DT) cells, and observed the induction of flat revertants. Krev-1(63E) induced a certain amount of flat colonies, while S29 rp alone also induced flat colonies at low frequencies. Interestingly, revertant-inducing activity of Krev-1(63E) was significantly enhanced by S29 rp. We have also demonstrated that a zinc finger-like domain of S29 rp indeed has a zinc binding activity and a derivative, S29 rp(ms), which was unable to bind zinc ion but still retained revertant inducing activity by itself, could not functionally interact with Krev-1(63E) protein.

Isolation of differentially expressed genes in carcinoma of the esophagus.

AbstractBackground: The genetic alterations that occur in the transformation of normal esophageal mucosa (NEM) to carcinoma of the esophagus (CAE) are not well understood. Differential display of mRNA is a recently described technique that uses reverse transcription and PCR to compare cDNA from paired normal and malignant tissue to determine whether there is either genetic loss (putative tumor suppressor gene) or overexpression (putative oncogene) in malignant cells. Our goal was to identify some of these genes from patients with CAE.nMethods: Specimens of NEM and corresponding CAE were obtained from patients at endoscopy or surgical resection and immediately snap frozen. Total RNA was isolated, reverse transcribed to cDNA, and PCR amplified with a predefined 10-mer oligonucleotide. The products were displayed on a polyacrylamide gel. Differential bands were isolated and sequenced and/or used as probes for Northern analysis.nResults: Application of the differential display method resulted in the isolation of 49 cDNA clones from three patients with CAE. Sequencing of the clones has revealed five unique sequences not previously reported and one that has been identified as histone H3.3. Northern analysis of histone H3.3 has revealed overexpression in four of six CAEs but not the paired NEM. In addition, whereas only 5 of 13 normal human cell lines of various origins overexpressed this gene, 11 of 12 human cancer cell lines (9 of 9 adenocarcinomas) overexpressed it.nConclusions: Differential display can be used to isolate potential oncogenes and tumor suppressor genes. We have identified five unique sequences and one known gene that may contribute to the development of CAE.

Cloning and sequence analysis of Hsp89αΔN, a new member of the Hsp90 gene family

Abstract We have identified a novel member of the Hsp90 gene family. This new gene, Hsp89αΔN , is remarkable in that it appears to represent a recent evolutionary event. Hsp89αΔN is identical in nucleotide sequence to Hsp89α for codons 224 to 732 (end). However, Hsp89αΔN cDNA lacks the ATP/geldanamycin binding domain (codons 1–220), instead containing 544 nucleotides of unique DNA at its 5′ end including 30 novel codons.

Expression of ETS Family of Genes in Systemic Lupus Erythematosis

Publisher Summary Systemic lupus erythematosus (SLE) is a chronic autoimmune disease of unknown etiology. SLE is characterized by the involvement of multiple organ systems and the production of autoantibodies directed against nuclear components, including ssDNA, ds- DNA, and histones. The hallmark of autoimmunity is the activation and proliferation of lymphocytes directed against self-antigen. Defect in the signal transduction cascade mechanisms in lymphocytes from SLE patients result in the aberrant expression of many genes and some of which encode DNA sequence specific transcription factors. These in turn regulate the transcription of genes contributing towards disease process. The chapter briefly describes the ETS gene family, the expression pattern of ETSl, ETS2, and ERGB/FLIl genes in lymphocytes from SLE patients, and the possible role of ERGB/FLIl transcription factor in the autoimmune disease process. The ETS genes encode sequence-specific DNA-binding proteins and function as transcription factors. ETS family of proteins is involved in lymphoid cell development, differentiation, maturation, and activation and therefore, they are important regulators of lymphoid gene expression. Inappropriate expression of ETS family of genes may have a detrimental effect on lymphoid cell differentiation, activation, and function. The chapter discusses the role of ETS in cancer and disease. This can occur by by activation through retroviral transduction of cellular sequences, retroviral promoter integration, or by chromosomal translocation, dysregulation of ETS. The chapter describes the expression of ETSl, ETS2 AND FLI1 genes during normal development, in lymphocytes from SLE patients, and in lymphocytes from autoimmune prone mice.