Choline Kinase Down-regulation Increases the Effect of 5-Fluorouracil in Breast Cancer Cells

Abstract

Identifying strategies to increase cancer cell kill while sparing normal tissue is critically important in cancer chemotherapy. Choline kinase (Chk), the enzyme that converts choline to phosphocholine (PC), is elevated in cancer cells and presents a novel target for increasing cell kill. Here, we have examined the effects of transiently down-regulating Chk by small interfering RNA against Chk (siRNA-chk) on PC and total choline-containing compound (tCho) levels and on the viability/proliferation of estrogen receptor-negative and estrogen receptor-positive breast cancer cell lines and a nonmalignant mammary epithelial cell line. We investigated the effects of combination treatment with transient siRNAchk transfection and the anticancer drug 5-fluorouracil (5-FU) in those cell lines. Microarray analysis of the invasive estrogen receptor-negative MDA-MB-231 cell line was done to characterize molecular changes associated with Chk downregulation. Chk down-regulation decreased PC and tCho levels in the malignant cell lines, whereas the cell viability/ proliferation assays detected a decrease in proliferation in these cells. In contrast, Chk down-regulation had an almost negligible effect on PC and tCho levels as well as cell viability/proliferation in the nonmalignant cell line. A combination of siRNA-chk with 5-FU treatment resulted in a larger reduction of cell viability/proliferation in the breast cancer cell lines; this reduction was evident to a much lesser degree in the nonmalignant cells. Microarray analysis showed that Chk down-regulation affected 33 proliferation-related genes and 9 DNA repair-related genes. Chk down-regulation with siRNA-chk may provide a novel alternative to enhance the effect of anticancer drugs in malignant cells. [Cancer Res 2007;67(23):11284-90]

1H HR‐MAS and genomic analysis of human tumor biopsies discriminate between high and low grade astrocytomas

“…Several authors have described increases in the expression of the genes of choline transport (33) and choline kinase (34,35). Choline kinase activity is coded by the a and b genes which give rise to three homodimeric (aa, bb) or heterodimeric (ab) isoforms of the enzyme (34,35). Present results parallel previous observations, suggesting that the genes coding for the choline transporter b or the b isoforms of choline kinase, are the ones responsible for the increase in PC in human gliomas.…”

Preclinical Characterization of RSM-932A, a Novel Anticancer Drug Targeting the Human Choline Kinase Alpha, an Enzyme Involved in Increased Lipid Metabolism of Cancer Cells

“…Combination of standard chemotherapy with newtargeted drugs represents a new strategy to efficiently and specifically target cancer cells to overcome resistance in some cases, reducing conventional schedules or dosage of the standard therapy (42). In vivo combination studies using ChoKa inhibitors with standard antineoplastic agents such as 5-fluorouracil (5-FU) have proven to be a promising strategy to increase efficacy in colorectal tumors (37) in keeping with previous treatments including ChoKa siRNA downregulation and 5-FU (43). Furthermore, resistance to ChoKa inhibitors is related to an increase of acid ceramidase (ASAH1) expression in lung primary tumors and derived cancer cell lines, making the combination of ChoKa and ASAH1 inhibitors a promising strategy to improve clinical outcome (44).…”

Direct Inhibition of Choline Kinase by a Near-Infrared Fluorescent Carbocyanine

“…Silencing ChoK via RNAi has been shown to reduce cell proliferation (21), enhance the sensitivity of aggressive cell lines to 5-fluorouracil (22), and reduce tumor growth rates (23) in breast cancer models. The choline mimetic, hemicholinium-3 (HC-3), has long been known to inhibit ChoK, but also interrupts neuronal choline transport and acetylcholinesterase activity (24).…”