Silencing Survivin Research Articles

The effect of survivin siRNA on apoptosis, proliferation and invasion by a colon carcinoma cell line

OBJECTIVE To study the efficiency of silencing survivin gene expression by an anti-survivin small RNA expression plasmid and to examine its impact on apoptosis, proliferation and invasive ability of the SW480 colorectal cancer cell line.

Effects of small interfering RNA magnetic nanoparticles combination with external magnetic fields on survivin gene expression of bladder cancer cells and apoptosis

To investigate the effects of the small interfering RNA plasmid-dextran magnetic nanoparticles (siRNA-DMN) combination with external magnetic fields on silencing survivin gene expression of bladder cancer cells and apoptosis when DMN used as gene carrier to transfer siRNA-survivin recombinant plasmid in vivo. The siRNA-survivin recombinant plasmid specific targeted survivin was synthesized in previous experiment. DMN were prepared by chemical coprecipitation method and used as gene carrier. The siRNA-DMN were constructed by static electricity of polylysine and transferred into human bladder cancer BIU-87 cells with the help of external magnetic fields. The growth inhibiting rate (IR) of BIU-87 cells was observed by 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyl tetrazolium bromide's test and the apoptosis index (AI) was detected by transferase-mediated dUTP nick end labeling method. The relatively transcription levels of survivin mRNA and protein expression were respectively detected by semi-quantitive reverse transcription polymerase chain reaction and Western Blotting techniques. The diameter, effective diameter and saturation magnetization of DMN-siRNA were about 10 - 12 nm, 94.8 nm and 0.19 emu/g, respectively. The IR (39.60%) and AI (28.72%), the relative expression of survivin mRNA and protein of siRNA-DMN combination with external magnetic fields on BIU-87 cells were significantly higher and lower than those in the control group and single siRNA-DMN group, respectively (P < 0.05). The siRNA-survivin plasmid-DMN combination with external magnetic fields could effectively inhibit survivin expression and induce BIU-87 cells apoptosis which provided experimental basis for the magnetic targeting gene therapy of bladder tumor.

Survivin stable knockdown by siRNA inhibits tumor cell growth and angiogenesis in breast and cervical cancers

Increased resistance to apoptosis is a hallmark of many tumor cells. Survivin, a member of IAP family protein, is expressed in many human cancers and plays an important role in protecting cells from apoptosis. Here we show that vector-based small interfering RNAs (siRNA) stably knockdown survivin expression in several cancer cell lines, leading to increased apoptotic rate in response to different proapoptotic stimuli, such as doxorubicin or TNF-α. The apoptotic susceptibility was dependent on divergent levels of survivin expression. The stable transfectants exhibited abnormal morphology, suppressed cell growth, enhanced spontaneous apoptosis and cell cycle hindrance. Furthermore, in nude mice xenografts of survivin-positive tumors, cells expressing survivin-targeted siRNAs exhibited decreased tumor formation and reduced angiogenesis. Results from these studies: (1) provide direct evidence that intracellular silencing of survivin by siRNA sensitizes human tumor cells to apoptosis; (2) define survivin as a promising molecular target for cancer therapy; and (3) suggest the potential applicability of survivin-targeted siRNA for treating human tumors, probably in combination with chemotherapy.

Survivin silencing sensitizes imatinib-resistant CML cells to the cytotoxic effect of hydroxyurea

13119 Background: Imatinib Mesylate (IM), a semi-specific inhibitor of the BCR-ABL tyrosine kinase, is currently the treatment of choice for Chronic Myeloid Leukemia (CML). However, about one third of CML patients treated with IM develop resistance to the drug because of reactivation of BCR-ABL kinase activity. This phenomenon is usually ascribed to the amplification of the BCR-ABL gene or to the selection of leukemic clones harboring point mutations that abrogate IM binding. To identify novel anti-apoptotic signaling pathways employed by BCR-ABL and devise strategies capable of killing IM-resistant CML cells, we investigated the interplay between BCR-ABL and the Inhibitor of Apoptosis Protein Survivin. Methods: Murine hematopoietic cells (32D) transduced with p210 BCR-ABL and human cell lines either positive (K562, KCL22, KYO1 and LAMA84) or negative (HL60) for the BCR-ABL oncoprotein, were analyzed for Survivin expression by western blot before and after IM treatment. Three different pathways (MAPK, PI3K and JAK2/STA3) potentially involved in BCR-ABL-mediated induction of Survivin were studied using inhibitors specific for each signaling cascade. The effect of Survivin on the proliferation and viability of IM-sensitive and IM-resistant CML cells was investigated after silencing Survivin expression with small interfering RNAs. Results: BCR-ABL tyrosine kinase activity induced an over-expression of Survivin in both human and murine hematopoietic cell lines. This over-expression was both at the transcriptional and the translational level and required the JAK2/STAT3 pathway. Survivin silencing by siRNA increased IM cytotoxicity in IM-sensitive cells but failed to restore IM efficacy in IM-resistant cells. However, Survivin silencing sensitized CML cells to the cytotoxic effect of hydroxyurea and enhanced the efficacy of this compound on three different murine cell lines are insensitive to IM because of point mutations in the BCR-ABL kinase domain (Ba/F3p210Y253F, Ba/F3p210D276G and Ba/F3p210T315I). Conclusions: Reduction of Survivin expression improves the efficacy of IM and increases the sensitivity of IM-resistant CML cells to hydroxyurea. Survivin may represent an attractive therapeutic target for both IM-sensitive and IM-resistant CML patients. No significant financial relationships to disclose.

Correlation of hMLH1 and HPP1 hypermethylation in gastric, but not in esophageal and cardiac adenocarcinoma

Deregulated epigenetic mechanisms are likely involved in the pathogenesis of myelodysplastic syndromes (MDSs). Which genes are silenced by aberrant promotor methylation during MDS hematopoiesis has not been equivalently investigated. Using an in vitro differentiation model of human hematopoiesis, we generated defined differentiation stages (day 0, day 4, day 7, day 11) of erythro-, thrombo- and granulopoiesis from 13 MDS patients and seven healthy donors. Promotor methylation analysis of key regulatory genes involved in cell cycle control (p14, p15, p16, CHK2), DNA repair (hMLH1), apoptosis (p73, survivin, DAPK), and differentiation (RARb, WT1) was performed by methylation-specific polymerase chain reaction. Corresponding gene expression was analyzed by microarray (Affymetrix, HG-U133A). We provide evidence that p16, survivin, CHK2, and WT1 are affected by promotor hypermethylation in MDSs displaying a selective International Prognostic Scoring System risk association. A methylation-associated mRNA downregulation for specific hematopoietic lineages and differentiation stages is demonstrated for survivin, CHK2, and WT1. We identified a suppressed survivin mRNA expression in methylated samples during erythropoiesis, whereas WT1 and CHK2 methylation-related reduction of mRNA expression was found during granulopoiesis in all MDS risk types. Our data suggest that lineage-specific methylation-associated gene silencing of survivin, CHK2, and WT1 in MDS hematopoietic precursor cells may contribute to the MDS-specific phenotype.