Modulation of IMPDH2, survivin, topoisomerase I and vimentin increases sensitivity to methotrexate in HT29 human colon cancer cells

Abstract

We determined differentially expressed genes in HT29 human colon cancer cells, both after short treatment with methotrexate (MTX) and after the resistance to MTX had been established. Screening was performed using Atlas Human Cancer 1.2K cDNA arrays. The analysis was carried out using Atlas image 2.01 and genespring 6.1 software. Among the differentially expressed genes we chose for further validation were inosine monophosphate dehydrogenase type II (IMPDH2), inosine monophosphate cyclohydrolase and survivin as up‐regulated genes, and topoisomerase I (TOP1) and vimentin as down‐regulated genes. Changes in mRNA levels were validated by quantitative RT‐PCR. Additionally, functional analyses were performed inhibiting the products of the selected genes or altering their expression to test if these genes could serve as targets to modify MTX cytotoxicity. Inhibition of IMPDH or TOP1 activity, antisense treatment against survivin, or overexpression of vimentin, sensitized resistant HT29 cells to MTX. Therefore, these proteins could constitute targets to develop modulators in MTX chemotherapy.

Interpopulation Variation Frequency of Human Inosine 5′-Monophosphate Dehydrogenase Type II (IMPDH2) Genetic Polymorphisms

“…IMPDH2 appears to have a greater role in patient response to mycophenolate therapy because it is five times more sensitive than IMPDH1 to inhibition by MPA. In addition to its role in immunosuppression therapy, studies have shown that IMPDH2 mRNA levels are elevated in tumor cells (Natsumeda and Carr, 1993) and are significantly associated with resistance to cancer chemotherapy (Penuelas et al, 2005;Hong et al, 2006;Fellenberg et al, 2007).…”

Quantitative evaluation of vimentin expression in tumour stroma of colorectal cancer

“…Recently, an association between vimentin and tumour development, progression, and chemosensitivity was suggested by various gene profiling studies (Zajchowski et al, 2001;Mellick et al, 2002;Penuelas et al, 2005). Vimentin was selectively overexpressed in highly aggressive breast cancer cells (Zajchowski et al, 2001).…”

A second target of benzamide riboside

“…One study reported that the DHFR amplified, MTX-resistant human adenocarcinoma cell line, HT29, is highly sensitive to BR and MTX combination treatment, but not sensitive to either BR or MTX alone. 21 It was suggested that concomitant inhibition of DHFR and IMPDH may account for the increased sensitivity observed. However our data suggests that downregulation of DHFR by BR may also contribute to drug synergism.…”