New Insights into the RNA-Based Mechanism of Action of the Anticancer Drug 5′-Fluorouracil in Eukaryotic Cells

Laura Mojardín,Margarita Salas,Sergio Moreno,Luis Quintales,Javier Botet,Heidar-Ali Tajmir-Riahi

doi:10.1371/journal.pone.0078172

Abstract

5-Fluorouracil (5FU) is a chemotherapeutic drug widely used in treating a range of advanced, solid tumours and, in particular, colorectal cancer. Here, we used high-density tiling DNA microarray technology to obtain the specific transcriptome-wide response induced by 5FU in the eukaryotic model Schizosaccharomyces pombe. This approach combined with real-time quantitative PCR analysis allowed us to detect splicing defects of a significant number of intron-containing mRNA, in addition to identify some rRNA and tRNA processing defects after 5FU treatment. Interestingly, our studies also revealed that 5FU specifically induced the expression of certain genes implicated in the processing of mRNA, tRNA and rRNA precursors, and in the post-transcriptional modification of uracil residues in RNA. The transcription of several tRNA genes was also significantly induced after drug exposure. These transcriptional changes might represent a cellular response mechanism to counteract 5FU damage since deletion strains for some of these up-regulated genes were hypersensitive to 5FU. Moreover, most of these RNA processing genes have human orthologs that participate in conserved pathways, suggesting that they could be novel targets to improve the efficacy of 5FU-based treatments.

Highlights

The antimetabolite 5-Fluorouracil (5FU) is an analogue of uracil widely used as a chemotherapeutic agent in the treatment of a variety of cancers. 5FU-based therapy has been shown to significantly increase both the response and survival rates for breast, neck and head cancer; its effectiveness is higher in advanced colorectal tumours [1]
Global Disruption of Pre-mRNA Splicing Caused by 5FU Despite increasing evidence that suggests that 5FU mainly exerts its cytotoxic effects through the inhibition of RNA metabolism, little is known about the global effects caused by 5FU in RNA processing and in mRNA splicing
A time-course and high-resolution survey of all differentially transcribed regions of the genome were obtained by comparing the transcriptional response of cells exposed to 500 mM of 5FU during 15, 60 or 240 minutes with respect to an untreated control

Summary

Introduction

The antimetabolite 5-Fluorouracil (5FU) is an analogue of uracil widely used as a chemotherapeutic agent in the treatment of a variety of cancers. 5FU-based therapy has been shown to significantly increase both the response and survival rates for breast, neck and head cancer; its effectiveness is higher in advanced colorectal tumours [1]. We selected three genes (rpc34, srp54 and SPAC1486.01) whose transcripts exhibited an increase in intron retention after 240 min of 5FU treatment, according to tiling microarray analysis (Table S3 and Figure 3A).

Results

Conclusion