Differential Effects of Antofine N-Oxide on Solid Tumor and Leukemia Cells

Abstract

We have studied the anti-cancer activities of antofine N-oxide isolated and purified from the medicinal plant Cynanchum vincetoxicum. Antofine N-oxide displayed a strong inhibitory effect on several solid tumor cell lines (glioblastoma, breast carcinoma and lung carcinoma) and on a T-cell leukemia cell line. Remarkably, its cytotoxic effect was considerably weaker in non-cancer cells. Antofine N-oxide was found to inhibit proliferation of the solid tumor cells whereas it caused apoptotic cell death in the leukemia cells. A microarray analysis after a short treatment revealed that the number of differentially expressed genes was considerably higher in solid tumor than in leukemia cells. Up-regulated genes in the three solid tumor cell lines include genes related to TNFα signaling, of which TNFα was among the most significantly induced. A functional analysis revealed that TNFR1 signaling was most likely activated in the solid tumor cells. The increased mRNA levels of several genes of this pathway (namely TNFα, TNFAIP3 and BIRC3) were confirmed by real-time quantitative PCR after different treatment durations. Finally a slight inhibition of NFκB-mediated transcription was observed in the same cells. Together our results suggest that inhibition of cell proliferation in solid tumor cells essentially occurs through TNFα signaling whereas this pathway is not activated in leukemia cells. Apoptotic cell death in the latter is induced by a distinct yet unknown pathway.

Medicinal Chemistry of Drugs with N-Oxide Functionalities

“…It inhibits the proliferation of brain, breast, and lung cancer cells and induces apoptosis in T-cell leukemia cells via TNFα signaling. An approximately 10-fold lower cytotoxicity of the compound in noncancerous fibroblasts suggests potential as an antitumor drug . A range of antofine derivatives (including many N -oxides) has been investigated with respect to their cytotoxicity.…”

“…An approximately 10-fold lower cytotoxicity of the compound in noncancerous fibroblasts suggests potential as an antitumor drug. 83 A range of antofine derivatives (including many N -oxides) has been investigated with respect to their cytotoxicity. However, a clear trend in the SAR of these compounds can hardly be derived from these studies.…”