Therapeutic potential of antisense oligodeoxynucleotides to down-regulate thymidylate synthase in mesothelioma

Abstract

Malignant mesothelioma is an aggressive tumor of the serosal surfaces of the lungs, heart, and abdomen. Survival rates are poor and effective treatments are not available. However, recent therapeutic regimens targeting thymidylate synthase (TS) in malignant mesothelioma patients have shown promise. We have reported the use of an antisense oligodeoxynucleotide targeting TS mRNA (antisense TS ODN 83) to inhibit growth of human tumor cells. To test the potential for antisense targeting of TS mRNA in treatment of malignant mesothelioma, we assessed and compared the effects of antisense TS ODN 83 on three human malignant mesothelioma cell lines (211H, H2052, and H28) and human nonmalignant mesothelioma cells (HT29 colorectal adenocarcinoma, HeLa cervical carcinoma, and MCF7 breast tumor cell lines). We report that ODN 83 applied as a single agent effectively reduced TS mRNA and protein in malignant mesothelioma cell lines. Furthermore, it inhibited malignant mesothelioma growth significantly more effectively than it inhibited growth of nonmalignant mesothelioma human tumor cell lines: a difference in susceptibility was not observed in response to treatment with TS proteintargeting drugs. In malignant mesothelioma cells, antisense TS both induced apoptotic cell death and reduced proliferation. In nonmalignant mesothelioma cells, only reduced proliferation was observed. Thus, antisense TSmediated induction of apoptosis may be the basis for the high malignant mesothelioma sensitivity to antisense targeting of TS. Further preclinical and clinical study of TS antisense oligodeoxynucleotides, alone and in combination with TS-targeting chemotherapy drugs, in mesothelioma is warranted.

Combining Small Interfering RNAs Targeting Thymidylate Synthase and Thymidine Kinase 1 or 2 Sensitizes Human Tumor Cells to 5-Fluorodeoxyuridine and Pemetrexed

“…2A) as reported previously (Ferguson et al, 1999Berg et al, 2001Berg et al, , 2002Flynn et al, 2006;Pandyra et al, 2007). When TK2 siRNA was combined with TS siRNA, it increased sensitivity to 5FUdR by approximately 25% more than treatment with TS siRNA alone (Fig.…”

“…2A). siRNA knockdown of TS before 5FUdR treatment enhanced the antiproliferative effect of 5FUdR by approximately 50%, as reported previously (Ferguson et al, 1999Flynn et al, 2006;Pandyra et al, 2007). However, when both TS and TK2 mRNA were decreased by siRNA before 5FUdR treatment (see Figs.…”

“…at ASPET Journals on May 12, 2018 jpet.aspetjournals.org specifically to TS-targeting drugs but not to chemotherapeutics that do not target TS (Flynn et al, 2006;Pandyra et al, 2007) and supports the hypothesis that modulation of TK activity affects sensitivity only to anti-TS drugs.…”

Enhanced Anticancer Effect of the Combination of BIBW2992 and Thymidylate Synthase–Targeted Agents in Non–Small Cell Lung Cancer with the T790M Mutation of Epidermal Growth Factor Receptor

“…Pemetrexed sensitivity has also been suggested to correlate inversely with TS expression in human cancer (26,27). Several preclinical studies also support such an inverse relation between TS expression and sensitivity to TS-targeted agents, likely reflecting the role of TS as a target for these drugs (28)(29)(30)(31). These observations support the notion that BIBW2992-induced downregulation of TS underlies, at least in part, the enhanced antitumor effect of combination therapy with either S-1 or pemetrexed.…”

Combination Silencer RNA (siRNA) Targeting Bcl-2 Antagonizes siRNA against Thymidylate Synthase in Human Tumor Cell Lines

“…Total protein (10 -30 g) was separated using 12% SDS-polyacrylamide gel electrophoresis, followed by transfer onto nitrocellulose membranes (GE Healthcare, Baie-d'Urfé, QC, Canada). Membranes were blocked for 16 h at 4°C with 5% skim milk powder in Tris-buffered saline with 0.2% Tween 20, and then they were probed at 25°C using a rabbit anti-human TS polyclonal antibody (Flynn et al, 2006) at 0.0625 g/ml or a monoclonal mouse anti-human Bcl-2 oncoprotein antibody (clone 24, 1:800; Dako Denmark A/S, Glostrup, Denmark) and an anti-actin antibody (1:1000; Sigma-Aldrich). After incubation with primary antibodies, membranes were washed with Tris-buffered saline with 0.2% Tween 20 and incubated for 1 h with horseradish peroxidaseconjugated anti-rabbit or anti-mouse antibodies (1:2000 and 1:3000, respectively) (GE Healthcare).…”