Silencing of survivin gene by small interfering RNAs produces supra-additive growth suppression in combination with 17-allylamino-17-demethoxygeldanamycin in human prostate cancer cells

Abstract

Survivin is an antiapoptotic gene, which is overexpressed in most human tumors and involved in mitotic checkpoint control. Recent evidence points to an essential role for heat shock protein 90 (Hsp90) in survivin function regulation. Although the survivin-Hsp90 association may promote tumor cell proliferation, it may also suggest new opportunities for the design of novel anticancer approaches. We evaluated the effect of small interfering RNA (siRNA) -mediated inhibition of survivin on the proliferative potential of prostate cancer cells and their sensitivity to the Hsp90 inhibitor 17-allylamino-17-demethoxygeldanamycin (17-AAG). Human androgenindependent prostate cancer cell lines (DU145 and PC-3) were transfected with four 21-mer double-stranded siRNAs (100 nmol/L) directed against different portions of survivin mRNA. After transfection, cells were collected and analyzed for survivin mRNA and protein expression, cell proliferation rate, ability to undergo apoptosis, and sensitivity to 17-AAG. Transfection of prostate cancer cells with siRNAs induced a variable extent of inhibition of survivin mRNA expression (39 -60% compared with controls), which was paralleled by a 38% to 75% reduction in survivin protein abundance. The three siRNAs able to induce the greatest inhibition of survivin expression also significantly reduced cell proliferation and enhanced the rate of apoptosis, with a concomitant increase in caspase-9 activity. Sequential treatment with siRNA and 17-AAG induced supra-additive antiproliferative effects in all cell lines, with an enhanced caspase-9-dependent apoptotic response. These findings suggest that combined strategies aimed at interfering with the survivin-Hsp90 connection may provide novel approaches for treatment of androgen-independent prostate cancer. [Mol Cancer Ther 2006;5(1):179 -86]

siRNA-mediated Silencing of Survivin Inhibits Proliferation and Enhances Etoposide Chemosensitivity in Acute Myeloid Leukemia Cells

“…In contrast, NC siRNA or lipofectamine treatments did not alter the survivin gene expression, cell proliferation and cell toxicity of etoposide, illustrating the specific impact of survivin siRNA. However, these observations are in agreement with the findings of similar studies on a variety of tumor cells, which further confirm the critical role of survivin in the survival, proliferation and chemoresistance of tumor cells (Nakao et al, 2006;Paduano et al, 2006;Miao et al, 2007;Song et al, 2008). The above-mentioned subjects show that the presence of survivin is necessary for the survival and drug resistance of leukemic cells.…”

Inhibition of the heat shock protein 90 molecular chaperone in vitro and in vivo by novel, synthetic, potent resorcinylic pyrazole/isoxazole amide analogues

“…This confirms the crucial network of hydrogen bonding interactions involving the resorcinol residue and pyrazole ring with Asp 93 , Thr 184 and a cluster of structurally conserved and highly ordered water molecules, as reported for CCT018159 (26,29). In addition, the C-5 ethylamide residue adds further hydrogen bond interactions with the protein backbone via Lys 58 and Gly 97 , the latter in particular contributing to the enhanced potency of VER-49009 over previous compounds lacking the amide group (29). Replacement of the central pyrazole in VER-49009 with an isoxazole gave VER-50589 ( Fig.…”

“…X-ray co-crystal structures showed a virtually identical binding mode for VER-49009 and VER-50589, involving key hydrogen bond interactions and water molecules. When compared with the equivalent structure for CCT018159 (26,29), further hydrogen bond interactions with Lys 58 and Gly 97 in the protein backbone of human HSP90a were achieved with the ethylamide residue of VER-49009 and VER-50589, the latter interaction in particular contributing to enhanced target and cellular potencies. All of the resorcinylic pyrazole/isoxazoles exhibit the same essential anchoring mechanism in which critical hydrogen bond interactions are formed between the ligand and Asp 93 , Thr 184 , and key water molecules at the base of the nucleotide binding pocket.…”

Induction of apoptosis of non-small cell lung cancer by a methylated oligonucleotide targeting survivin gene

“…As NSCLC cells express the highest level of survivin found in humor tumor, 4 inhibition of survivin would block the anti-apoptosis and mitotic progression in NSCLC. The molecular antagonists of survivin, including antisense, ribozymes, siRNA or dominant negative mutants have been successfully utilized to inhibit survivin expression or to interfere with its functions, inducing apoptosis and inhibiting tumor growth in vitro and in vivo, [21][22][23][24][25][26][27][28][29] As there are only two survivin alleles in each cell compared with hundreds of thousands of survivin mRNA molecules, an antigene strategy at the transcriptional level probably possesses advantage over antisense, RNAi or ribozyme-based techniques. Recently, Yao et al 20 have devised a method to inhibit transcriptional initiation by constructing short methylated oligonucleotides which induce DNA methylation at specific loci.…”