Phenotype-dependent apoptosis signalling in mesothelioma cells after selenite exposure

<p>Abstract</p> <p>Background</p> <p>Selenite is a promising anticancer agent which has been shown to induce apoptosis in malignant mesothelioma cells in a phenotype-dependent manner, where cells of the chemoresistant sarcomatoid phenotype are more sensitive.</p> <p>Methods</p> <p>In this paper, we investigate the apoptosis signalling mechanisms in sarcomatoid and epithelioid mesothelioma cells after selenite treatment. Apoptosis was measured with the Annexin-PI assay. The mitochondrial membrane potential, the expression of Bax, Bcl-XL, and the activation of caspase-3 were assayed with flow cytometry and a cytokeratin 18 cleavage assay. Signalling through JNK, p38, p53, and cathepsins B, D, and E was investigated with chemical inhibitors. Furthermore, the expression, nuclear translocation and DNA-binding activity of p53 was investigated using ICC, EMSA and the monitoring of p21 expression as a downstream event. Levels of thioredoxin (Trx) were measured by ELISA.</p> <p>Results</p> <p>In both cell lines, 10 μM selenite caused apoptosis and a marked loss of mitochondrial membrane potential. Bax was up-regulated only in the sarcomatoid cell line, while the epithelioid cell line down-regulated Bcl-XL and showed greater caspase-3 activation. Nuclear translocation of p53 was seen in both cell lines, but very little p21 expression was induced. Chemical inhibition of p53 did not protect the cells from apoptosis. p53 lost its DNA binding ability after selenite treatment and was enriched in an inactive form. Levels of thioredoxin decreased after selenite treatment. Chemical inhibition of MAP kinases and cathepsins showed that p38 and cathepsin B had some mediatory effect while JNK had an anti-apoptotic role.</p> <p>Conclusion</p> <p>We delineate pathways of apoptosis signalling in response to selenite, showing differences between epithelioid and sarcomatoid mesothelioma cells. These differences may partly explain why sarcomatoid cells are more sensitive to selenite.</p

Early transcriptional response in the jejunum of germ-free piglets after oral infection with virulent rotavirus

Germ-free piglets were orally infected with virulent rotavirus to collect jejunal mucosal scrapings at 12 and 18 hours post infection (two piglets per time point). IFN-gamma mRNA expression was stimulated in the mucosa of all four infected piglets, indicating that they all responded to the rotavirus infection. RNA pools prepared from two infected piglets were used to compare whole mucosal gene expression at 12 and 18 hpi to expression in uninfected germ-free piglets (n = 3) using a porcine intestinal cDNA microarray. Microarray analysis identified 13 down-regulated and 17 up-regulated genes. Northern blot analysis of a selected group of genes confirmed the data of the microarray. Genes were functionally clustered in interferon-regulated genes, proliferation/differentiation genes, apoptosis genes, cytoskeleton genes, signal transduction genes, and enterocyte digestive, absorptive, and transport genes. Down-regulation of the transport gene cluster reflected in part the loss of rotavirus-infected enterocytes from the villous tips. Data mining suggested that several genes were regulated in lower- or mid-villus immature enterocytes and goblet cells, probably to support repair of the damaged epithelial cell layer at the villous tips. Furthermore, up-regulation was observed for IFN-γ induced guanylate binding protein 2, a protein that effectively inhibited VSV and EMCV replication in vitro (Arch Virol 150:1213–1220, 2005). This protein may play a role in the small intestine’s innate defense against enteric viruses like rotavirus

Platinum resistance in breast and ovarian cancer cell lines

Breast and ovarian cancers are among the 10 leading cancer types in females with mortalities of 15% and 6%, respectively. Despite tremendous efforts to conquer malignant diseases, the war on cancer declared by Richard Nixon four decades ago seems to be lost. Approximately 21,800 women in the US will be diagnosed with ovarian cancer in 2011. Therefore, its incidence is relatively low compared to breast cancer with 207.090 prognosed cases in 2011. However, overall survival unmasks ovarian cancer as the most deadly gynecological neoplasia. Platinum-based chemotherapy is emerging as an upcoming treatment modality especially in triple negative breast cancer. However, in ovarian cancer Platinum-complexes for a long time are established as first line treatment. Emergence of a resistant phenotype is a major hurdle in curative cancer therapy approaches and many scientists around the world are focussing on this issue. This review covers new findings in this field during the past decade

Molecular fingerprinting of radiation resistant tumors: Can we apprehend and rehabilitate the suspects?

Radiation therapy continues to be one of the more popular treatment options for localized prostate cancer. One major obstacle to radiation therapy is that there is a limit to the amount of radiation that can be safely delivered to the target organ. Emerging evidence suggests that therapeutic agents targeting specific molecules might be combined with radiation therapy for more effective treatment of tumors. Recent studies suggest that modulation of these molecules by a variety of mechanisms (e.g., gene therapy, antisense oligonucleotides, small interfering RNA) may enhance the efficacy of radiation therapy by modifying the activity of key cell proliferation and survival pathways such as those controlled by Bcl-2, p53, Akt/PTEN and cyclooxygenase-2. In this article, we summarize the findings of recent investigations of radiosensitizing agents in the treatment of prostate cancer

Changes in gene expression induced by thioredoxin-1 in MCF-7 human breast cancer cells

Thioredoxin-1 (Trx-1) is a small redox protein that is overexpressed in a number of human cancers. Elevated levels of Trx-1 in tumors is associated with increased cell proliferation, decreased apoptosis, and decreased patient survival. However, the mechanism(s) for the growth stimulating and anti-apoptosis effects of Trx-1 are unknown. We used DNA microarray technology to identify genes whose expression was altered in MCF-7 breast cancer cells stably transfected with wild-type Trx-1 (MCF-7/Trx 9) or a redox inactive mutant Trx-1 (MCF-7/SerB 4) compared to empty-vector transfected cells (MCF-7/neo). The expression of cytochrome P450 1B1 (CYP1B1) mRNA and protein is increased by Trx-1 transfection of MCF-7 human breast cancer cells and decreased by a redox inactive mutant Trx-1. CYP1B1 is a tumor specific CYP which converts 17β-estradiol (E₂) to the carcinogenic 4-hydroxyestradiol (4-OHE₂). The expression of peroxiredoxin 1 (PRDX1) mRNA is increased as a result of Trx-1 overexpression in MCF-7 cells. The peroxiredoxins belong to a conserved family of antioxidant proteins that use thiol groups as reducing equivalents to scavenge oxidants. Transfection of mouse WEHI7.2 thymoma cells with human PRDX1 protects cells from apoptosis induced by H₂O₂. Spermine/spermidine N'-acetyltransferase (SSAT) mRNA expression and enzyme activity is decreased by Trx-1 transfection of MCF-7 human breast cancer cells. SSAT is an important enzyme in the polyamine catabolic pathway. The inhibition of SSAT enzyme activity is associated with decreased putrescine levels in the Trx-1 transfected cells. Therefore, it appears as if the modification of cellular redox signaling brought about by the overexpression of Trx-1 in breast cancer cells induces changes in gene expression that contribute to the transformed phenotype. Trx-1 redirects estrogen metabolism in a more toxic pathway due to the induction of CYP1B1, provides resistance to apoptosis induced by reactive oxygen species via the upregulation of PRDX1, and alters polyamine metabolism by inhibiting the expression of SSAT

Relación entre los niveles plasmáticos de selenio y las diferentes enfermedades prostáticas

Diversos estudios han demostrado una relación inversa entre los niveles séricos de selenio (Se) y la detección de cáncer de próstata (CaP) avanzado. Objetivo: Determinar y comparar los niveles plasmáticos de Se en pacientes con diferentes enfermedades prostáticas. Materiales y métodos: El estudio fue transversal, descriptivo y comparativo. La población estuvo constituida por 64 hombres de entre 50-80 años, seleccionados luego de una consulta urológica de rutina durante el período 2007-2009. Se realizó una historia clínica detallada, tacto rectal, determinación de PSA y concentración plasmática de Se mediante una técnica espectrofotométrica para glutatión peroxidasa en sangre entera (Kit Ransel, Randox SRL, Crumlin, UK). Las afecciones prostáticas se establecieron por biopsia transrectal ecodirigida (12-14 tomas) y el grado tumoral por score de Gleason. El análisis estadístico se realizó mediante ANOVA I (p<0,05). Resultados: La concentración media de Se en los individuos controles (n=10) fue de 33,75±2,36mg/ml, en los pacientes con enfermedad benigna (n=41) de 23,08±1,57mg/ml y en los casos con CaP (n=13) de 12,281,03mg/ml (p<0,0001). Se observó una disminución del 31,6% en los pacientes con enfermedad prostática benigna y de un 63,6% en aquellos con CaP en relación con los controles. No se observaron diferencias estadísticamente significativas entre el score de Gleason y los valores de glutatión peroxidasa. Conclusión: Los sujetos con enfermedad prostática, tanto benigna como maligna, tienen niveles de Se en sangre menores que los individuos sanos