Antisense down-regulation of thymidylate synthase to suppress growth and enhance cytotoxicity of 5-FUdR, 5-FU and Tomudex in HeLa cells.

摘要: Thymidylate synthase (TS), the key enzyme in de novo synthesis of thymidine, is an important target for antitumour chemotherapy. It was hypothesized that antisense oligonucleotide down-regulation TS mRNA would decrease levels and enhance cytotoxicity inhibitors TS, including pyrimidine analogues 5-fluorouracil (5-FU) 5-fluorodeoxyuridine (5-FUdR), folate analogue Tomudex (ICI D1694; N-(5-[N-(3,4-dihydro-2-methyl-4-oxoquinazolin-6-ylmethyl)-N-methylamino]-2-theonyl-L-glutamic acid). 2′-Methoxyethoxylated, phosphorothioated 20-mer oligodeoxynucleotides (ODNs), complementary to various sequences mRNA, were synthesized, along with control oligomers consisting same, respective bases randomized order, against which all biological effects compared. Following a 6-h transfection HeLa cells using polycationic liposome at 3 μg ml−1, ODN 83 (50 nM), region 3′-untranslated decreased by approximately 70% within 24 h. also activity, as measured binding radiolabelled monophosphate. In addition inhibiting proliferation up 40%, enhanced or 5-FU, added 1 day following transfection, 50–60%. sensitivity 5-FUdR 70%, but did not affect toxicity cisplatin, chlorambucil, melphalan, doxorubicin, ionizing radiation, paclitaxel, irinotecan. These data indicate can inhibit human tumour cell efficacy TS-targeted drugs. British Journal Pharmacology (1999) 127, 1777–1786; doi:10.1038/sj.bjp.0702728