Abstract 2340: Ribonucleotide reductase subunit M2 promotes cell invasiveness and motility in lung and head and neck cancer cells

Abstract

Abstract Ribonucleotide reductase subunit M2 (RRM2) has been frequently observed to be aberrantly overexpressed in various tumors. RRM2 is a key enzyme involved in the production of 2′-deoxyribonucleoside 5′-triphosphates required for DNA synthesis. In addition to DNA synthesis, it has been reported that RRM2 modulates cellular invasiveness. However, the mechanisms through which RRM2 affects the invasive phenotype have not been elucidated. In our study, we examined the role of RRM2 in cell invasion and migration of different lung (A549, H460 and H1299) and head and neck (Tu686) cancer cell lines. To explore the mechanism underlying RRM2's activity, we applied small interference RNA (siRNA) to knockdown the RRM2 protein while pcDNA3/RRM2 plasmid was used to establish RRM2 overexpressing stable cell lines. Our results revealed varying degrees of RRM2 expression levels in lung and head and neck cancer cell lines, which were proportionally correlated with the invasive capability of cells. H1299, a cell line that features epithelial-mesenchymal transition (EMT) expressed the highest level of RRM2 protein among the cell lines studied, and exhibited the greatest invasive and migratory abilities as demonstrated by Boyden chamber invasion and wound healing assays. H1299 was 6-fold more invasive than A549, which has lower RRM2 expression. Moreover, gain of function analysis demonstrated that overexpression of RRM2 enhanced cell invasiveness and motility in low RRM2-expressing cell lines A549 and Tu686. Western blots revealed that markers associated with tumor cell invasion and migration such as phospho-Src, phospho-FAK, phospho-calveolin-1, phospho-Akt, phospho-Erk, and MMP-9 secretion were induced whereas E-cadherin protein expression was significantly inhibited in RRM2 overexpressing cell lines. In contrast, loss of function analysis showed that siRNA targeting RRM2 decreased RRM2 expression and attenuated cellular invasiveness and motility in both lung and head and cancer cell lines. Our study demonstrated that RRM2 substantially promoted cell invasion and migration abilities. An elevated RRM2 may serve as a potential biomarker for metastasis of head and neck and lung cancer. Thus, targeting RRM2 and its downstream signaling intermediaries represents a rational approach for developing novel anticancer therapeutics. (This work is supported by grants from NIH U54CA119338-04, P50CA128613 and DOD W81XWH-07-1-0306). Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2340. doi:10.1158/1538-7445.AM2011-2340