NCI60 Cancer Cell Line Panel Data and RNAi Analysis Help Identify EAF2 as a Modulator of Simvastatin and Lovastatin Response in HCT-116 Cells

Sevtap Savas,Irma M Gonzales,Hamdi Jarjanazi,Yun Hee Choi,Shilpi Arora,Laurent Briollais,Irada Ibrahim-Zada,Hilmi Ozcelik,Meredith C Henderson,David O Azorsa,Sukru Tuzmen,Eric Bernhard

doi:10.1371/journal.pone.0018306

Abstract

Simvastatin and lovastatin are statins traditionally used for lowering serum cholesterol levels. However, there exists evidence indicating their potential chemotherapeutic characteristics in cancer. In this study, we used bioinformatic analysis of publicly available data in order to systematically identify the genes involved in resistance to cytotoxic effects of these two drugs in the NCI60 cell line panel. We used the pharmacological data available for all the NCI60 cell lines to classify simvastatin or lovastatin resistant and sensitive cell lines, respectively. Next, we performed whole-genome single marker case-control association tests for the lovastatin and simvastatin resistant and sensitive cells using their publicly available Affymetrix 125K SNP genomic data. The results were then evaluated using RNAi methodology. After correction of the p-values for multiple testing using False Discovery Rate, our results identified three genes (NRP1, COL13A1, MRPS31) and six genes (EAF2, ANK2, AKAP7, STEAP2, LPIN2, PARVB) associated with resistance to simvastatin and lovastatin, respectively. Functional validation using RNAi confirmed that silencing of EAF2 expression modulated the response of HCT-116 colon cancer cells to both statins. In summary, we have successfully utilized the publicly available data on the NCI60 cell lines to perform whole-genome association studies for simvastatin and lovastatin. Our results indicated genes involved in the cellular response to these statins and siRNA studies confirmed the role of the EAF2 in response to these drugs in HCT-116 colon cancer cells.

Highlights

Simvastatin and lovastatin are two statins traditionally used for lowering serum cholesterol levels
The results obtained from the whole-genome case-control association studies for simvastatin and lovastatin are summarized in Tables 1 and 2, respectively
Five of the single nucleotide polymorphisms (SNPs) were located in intergenic regions, whereas the remaining three SNPs were located in introns of known genes (Table 3), namely, intron 6 of NRP1, intron 37 of COL13A1, and intron 6 of MRPS31

Summary

Introduction

Simvastatin and lovastatin are two statins traditionally used for lowering serum cholesterol levels. The statins are reversible inhibitors of the microsomal enzyme HMG-CoA reductase, which converts HMG-CoA to mevalonate. This is an early rate-limiting step in cholesterol biosynthesis. Inhibition of HMGCoA reductase by statins decreases intracellular cholesterol biosynthesis, which leads to transcriptionally upregulated production of microsomal HMG-CoA reductase and cell surface LDL receptors. Simvastatin and lovastatin differ in some important aspects concerning the degree of metabolism and the number of active and inactive metabolites [1]. The role of statins in cholesterol metabolism can explain their potential cytotoxic characteristics

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Discussion

Conclusion