Antisense Inhibition of Methylenetetrahydrofolate Reductase Reduces Cancer Cell Survival In vitro and Tumor Growth In vivo

Abstract

Purpose: Many cancer lines are methionine dependent and decrease proliferation when methionine supply is limited. Methylenetetrahydrofolate reductase (MTHFR) generates the folate derivative for homocysteine remethylation to methionine. We investigated the effect of antisensemediated inhibition of MTHFR on survival of human cancer cells.Experimental Design: We examined the in vitro and in vivo anticancer effects of a combination of MTHFR antisense and standard cytotoxic drugs.Results: Specific antisense against MTHFR (EX5) showed significant inhibitory effects on growth of human colon, lung, breast, prostate, and neuroblastoma tumor cells in vitro compared with that of the control oligonucleotide. Cytotoxic drugs (5-fluorouracil, cisplatin, or paclitaxel) potentiated the effect of EX5. In vivo, antisense alone or in combination with cytotoxic drugs inhibited the growth of human colon and lung carcinoma xenografts. In comparison with control oligonucleotide, treatment with EX5 inhibited growth of colon tumors and lung tumors by 60% and 45%, respectively. EX5 with 5-fluorouracil decreased growth of colon tumors by an additional 30% compared with EX5 alone, and EX5 with cisplatin decreased growth of lung tumors by an additional 40% compared with cisplatin alone. Growth inhibition by EX5 was associated with decreased amounts of MTHFR protein and with increased amounts of an apoptosis marker.Conclusions: Our results confirm that MTHFR inhibition decreases tumor growth and suggest that inhibition of MTHFR by antisense or small molecules may be a novel anticancer approach.

The MTHFR C677T Polymorphism and Prostate Cancer Risk: New Findings from a Meta-analysis of 7306 Cases and 8062 Controls

“…Such protective role of the polymorphism was what we observed from Asian studies. Moreover, Stankova suggested antisense inhibition of MTHFR could reduce cancer cell survival in vitro and tumor growth in vivo (Stankova et al, 2005), and such inhibition produced similar effect as the polymorphism. But why did opposite effect exist in studies from Europe.…”

Folate restriction and methylenetetrahydrofolate reductase 677T polymorphism decreases adoMet synthesis via folate-dependent remethylation in human-transformed lymphoblasts

“…25 Antisense against MTHFR showed significant inhibitory effects in growth of human colon, lung, breast, prostate and neuroblastoma tumor cells in vitro and it was suggested that inhibition of MTHFR may be a novel anticancer approach. 26 Global genomic hypomethylation is associated with malignant lymphoproliferative diseases. 27 Aberrant DNA methylation of promoter-associated CpG islands is very common in hematological malignancies 28 including adult acute lymphoblastic leukemia 29,30 and cutaneous T-cell lymphoma, 31 the profile of CpG island hypermethylation in hematologic malignancies could be an epigenetic signature unique for each subtype of leukemia or lymphoma.…”

Methylenetetrahydrofolate Reductase C677T is Not Associated with Expression of Pyrimidine Metabolic Enzyme Genes in Colorectal Cancer

“…Similarly, an antisense sequence against MTHFR mediated the downregulation of gene expression and inhibited tumour growth in vivo and in vitro. 4,17 Backus et al 18 reported that cancer cell lines cultured with high concentrations of folate showed higher expression and catalytic activity of TS protein than those grown at low folate levels. The findings of the present investigation, however, suggest that MTHFR polymorphism does not increase TS gene expression.…”