Biomedical subjects

E Parganas

Publications and source records attributed to E Parganas.

22 records · Page 2Linked to original sources

PubMed1990

The human Evi-1 gene is located on chromosome 3q24-q28 but is not rearranged in three cases of acute nonlymphocytic leukemias containing t(3;5)(q25;q34) translocations.

The murine Evi-1 gene encodes a protein that has multiple 28-amino acid repeats containing the consensus sequence found in the zinc finger domains of many transcriptional regulatory proteins. Activation of the expression of the Evi-1 gene is frequently found in murine myeloid leukemias and leukemia cell lines and is due to retroviral insertions in the 5' region of the gene in either the Evi-1 or the CB-1/FIM3 common sites of viral integrations. To examine the role of the Evi-1 gene in human leukemias we have cloned regions of the human locus corresponding to the coding region of the gene and regions corresponding to the Evi-1 and CB-1/FIM3 common sites of integrations. Using these probes we demonstrate that the human Evi-1 gene maps to chromosome 3q24-q28 in a region that is translocated in acute nonlymphocytic leukemias with a t(3;5)(q25;q34). By in situ hybridization with metaphase chromosomes from one patient with a 3;5 translocation, the Evi-1 gene was found to be translocated to the derivative 5 chromosome. However, no rearrangements were detected by Southern blot analysis with DNAs from three patients with a t(3;5) using probes from the Evi-1 or CB-1/FIM3 loci. No Evi-1 transcripts were detected with RNA from leukemic blasts of one patient with a t(3;5).

Blotting, Northern↗

PubMed1990

Unique expression of the human Evi-1 gene in an endometrial carcinoma cell line: sequence of cDNAs and structure of alternatively spliced transcripts.

Retroviral insertional activation of the expression of the Evi-1 is one of the most common events associated with transformation in murine myeloid leukemia. The murine Evi-1 gene encodes a 145 kDa nuclear, DNA binding protein that contains two domains containing seven and three sets of repeats of the zinc finger motif. During studies to determine the role of the Evi-1 gene in the transformation of human cells, we have found that the Evi-1 gene is uniquely expressed at low levels in HEC-1-A cells and at high levels in HEC-1-B cells, two related human endometrial carcinoma cell lines. cDNA clones were isolated and sequenced from the HEC-1-B cell line. The human gene is highly homologous to the murine gene and shows 91% and 94% homology in nucleotide or amino acid sequence respectively. In addition an alternatively spliced form of the gene was identified that encodes a protein with an internal deletion 315 amino acids including two of the zinc finger repeats. The possible basis for the unique expression of the Evi-1 gene by HEC-1 cells could not be determined by karyotype or Southern blot analysis.

Amino Acid Sequence↗

PubMed1989

Reduced formation of lesions in the DNA of a multidrug-resistant L1210 subline selected for teniposide resistance.

Earlier studies have suggested that higher cellular levels of teniposide (VM-26) are required for the inhibition of growth in L1210/VM-26 sublines than in parental L1210 cells. On the basis of this observation, we hypothesized that resistance to VM-26, which is partly attributed to multidrug resistance, also resulted in reduced formation of DNA lesions by the drug. In confirmation of this hypothesis, equitoxic concentrations of VM-26 produced fewer breaks in the DNA of LIa5 microM cells, the prototype L1210/VM-26 subline, than in that of L1210 cells. Previously, potassium cyanide (KCN) and verapamil were shown to increase the levels of VM-26 in LIa5 microM but not L1210 cells. These agents also selectively increased the formation of breaks in the DNA of LIa5 microM but not L1210 cells. The DNA unknotting assay with phage P4 DNA indicated equivalent DNA type II topoisomerase activity in nuclear extracts of LIa5 microM and L1210 cells. The factor that reduced the formation of breaks in cellular LIa5 microM DNA by VM-26 provided less protection against equitoxic levels of doxorubicin, to which LIa5 microM cells are cross-resistant.

Animals↗

PubMed1987

Expressions of resistance and cross-resistance in teniposide-resistant L1210 cells.

Resistance to teniposide (VM-26) by VM-26 selected resistant L1210 cells in culture was attributed to alterations in the flux of VM-26 across the plasma membrane and to functions of homogeneously staining regions that appeared on one or more chromosomes. In the present study, electrophoresis of membrane-cytosol fractions of these resistant sublines demonstrated a protein band, Mr 22 kd, that was not evident in similar fractions of drug-sensitive L1210 cells or three revertant sublines. The distribution of this protein among various cellular fractions could be altered by manipulation of the concentration of calcium ions. A representative subline, LIa5 microM, was observed to have vesicles that reacted with Sudan black B stain, an indication of altered lipid metabolism. The LIa5 microM subline was cross-resistant to etoposide, vincristine, doxorubicin, amsacrine, and actinomycin D. Concentrations of VM-26 that inhibited cell division to the same extent caused an accumulation of fewer cells in the G2 stage of cell division in LIa5 microM cultures than in L1210 cultures. These observations indicate that the LIa5 microM subline expressed multiple drug resistance, as well as changes in the expression of cytotoxicity to VM-26.

Animals↗