Analysis of telomerase activity and RNA expression in a patient with acute promyelocytic leukemia treated with all-trans retinoic acid

Regulation of telomerase activity by apparently opposing elements

Telomeres, the ends of chromosomes, undergo frequent remodeling events that are important in cell development, proliferation and differentiation, and neoplastic immortalization. It is not known how the cellular environment influences telomere remodeling, stability, and lengthening or shortening. Telomerase is a ribonucleoprotein complex that maintains and lengthens telomeres in the majority of cancers. Recent studies indicate that a number of factors, including hormones, cytokines, ligands of nuclear receptor, vitamins and herbal extracts have significantly influence telomerase activity and, in some instances, the remodeling of telomeres. This review summarizes the advances in understanding of the positive and negative regulation by extracellular factors of telomerase activity in cancer, stem cells and other systems in mammals.

Down-regulation of wt1 expression in leukemia cell lines as part of apoptotic effect in arsenic treatment using two compounds

Arsenic trioxide (As2O3) induces remission in patients with acute promyelocytic leukemia (APL). To better understand molecular mechanisms of arsenic actions, this study investigated the effect of two different arsenic compounds on gene expression of apoptosis and cellular proliferation related genes. The Wilms' tumor gene (wt1) is up-regulated in acute myeloid leukemia (AML) and a variety of leukemia cell lines. The expression of wt1 in these cells is proposed to have an anti-apoptotic effect. HL-60 and K562 were treated with arsenic trioxide (As2O3) and sodium arsenite (NaAsO2) at concentrations between 0 - 10 microM for up to 48 h. The induction of apoptosis was accompanied by down-regulation of hTERT and wt1 mRNA and protein expression but up-regulation of par-4. Low concentrations of 0.1 microM arsenic induced expression of the anti-apoptotic bcl-2 gene in both cell lines HL-60 and K562. There were no major differences encountered between compounds. After arsenic treatment of the leukemia cell lines HL-60 and K562 the up-regulation of par-4 may contribute to the induction of apoptosis rather than down-regulation of bcl-2. The therapeutic effect of arsenic is the induction of apoptosis by modulating the gene expression profile of pro- and anti-apoptotic genes including the wt1 gene.

Fresh-frozen, optimal cutting temperature (OCT) compound-embedded bone marrow aspirates: a reliable resource for morphological, immunohistochemical and molecular examinations

The usefulness of fresh-frozen, optimal cutting temperature (OCT) compound-embedded (FFOE) bone marrow (BM) aspirates was evaluated as a reliable resource for morphological, immunohistochemical and molecular examinations. One hundred BM aspirates were collected in polypropylene tubes and immediately frozen for 2 h in a deep freezer. Frozen BM was transferred to a cryomold filled with OCT compound and the prepared samples were stored in a deep freezer. Histological examination and immunohistochemical staining, polymerase chain reaction (PCR), sequencing and reverse transcription (RT)-PCR were performed to evaluate the quality of the FFOE BM sections in 10% of randomly selected samples. FFOE BM sections revealed better morphologies than paraffin-embedded clot sections in haematoxylin and eosin staining because mature erythrocytes were removed during the staining process in frozen BM sections. Immunohistochemical staining for CD34 revealed excellent staining quality and oil red O staining showed that fat vacuoles in cells were well preserved. The quality of genomic DNA in FFOE BM sections was suitable for obtaining about 2000 bp PCR product for the human leucocyte antigen-A locus followed by direct sequencing of the sample, and the quality of total RNA was suitable for detection of BCR-ABL fusion transcript. FFOE BM aspirates are a reliable resource for various laboratory tests of diagnostic and research arenas.

JWA is required for the antiproliferative and pro-apoptotic effects of all-trans retinoic acid in Hela cells

1. All-trans retinoic acid (ATRA) is known to inhibit cellular proliferation and induce differentiation and apoptosis. It usually activates gene expression by binding to a nuclear receptor that interacts with retinoic acid-response elements (RARE) and then activates the mitogen-activated protein kinase signal pathway. JWA, a newly identified ATRA-responsive gene, has recently been proposed as an important molecule for cellular differentiation induced by some chemicals, including ATRA. 2. To investigate the possible involvement of JWA in the inhibition of cellular proliferation and induction of apoptosis by ATRA, HeLa cells were stably transfected with sense or antisense JWA to establish cell lines that overexpressed or were deficient in JWA; ATRA (0.05-10 micromol/L) was used to induce cellular differentiation and apoptosis. 3. Western blot analysis revealed that ATRA caused increased expression of JWA in HeLa cells in a dose- and time-dependent manner, accompanied by activation of extracellular signal-regulated kinase (ERK) 1/2 phosphorylation. However, ERK1/2 phosphorylation induced by ATRA was inhibited in JWA-deficient HeLa cells. In JWA-overexpressing HeLa cells, ATRA showed more significant antiproliferative effects and induced more apoptosis. 4. The reporter gene assay showed that ATRA (5 mmol/L) enhanced the transcriptional activity of JWA by interacting with its promoter in the region from -194 to +107 bp (P < 0.01). Bioinformatic analysis indicated that the JWA promoter did not contain RARE, but did contain two CCAAT boxes in this fragment spanning -194 to +107 bp, which may be responsive to the ATRA-activated nuclear transcription factor CCAAT/enhancer binding proteins (C/EBP) or interacting proteins. Therefore, ATRA-inhibited cellular proliferation and -induced apoptosis in HeLa cells may be dependent on JWA transactivation via its C/EBP-binding motifs. 5. These data indicate that the inhibition of proliferation and the induction of apoptosis by ATRA are dependent on JWA expression in HeLa cells. The findings may represent a novel mechanism by which the effects of ATRA in regulating cellular proliferation and apoptosis are mediated, at least in part, by JWA expression.