ISG15 as a novel tumor biomarker for drug sensitivity.

Journal Article (Journal Article)

Tumor cells are known to exhibit highly varied sensitivity to camptothecins (CPT; e.g., irinotecan and topotecan). However, the factors that determine CPT sensitivity/resistance are largely unknown. Recent studies have shown that the ubiquitin-like protein, IFN-stimulated gene 15 (ISG15), which is highly elevated in many human cancers and tumor cell lines, antagonizes the ubiquitin/proteasome pathway. In the present study, we show that ISG15 is a determinant for CPT sensitivity/resistance possibly through its effect on proteasome-mediated repair of topoisomerase I (TOP1)-DNA covalent complexes. First, short hairpin RNA-mediated knockdown of either ISG15 or UbcH8 (major E2 for ISG15) in breast cancer ZR-75-1 cells decreased CPT sensitivity, suggesting that ISG15 overexpression in tumors could be a factor affecting intrinsic CPT sensitivity in tumor cells. Second, the level of ISG15 was found to be significantly reduced in several tumor cells selected for resistance to CPT, suggesting that altered ISG15 regulation could be a significant determinant for acquired CPT resistance. Parallel to reduced CPT sensitivity, short hairpin RNA-mediated knockdown of either ISG15 or UbcH8 in ZR-75-1 cells resulted in increased proteasomal degradation of CPT-induced TOP1-DNA covalent complexes. Taken together, these results suggest that ISG15, which interferes with proteasome-mediated repair of TOP1-DNA covalent complexes, is a potential tumor biomarker for CPT sensitivity.

Full Text

Duke Authors

Cited Authors

  • Desai, SD; Wood, LM; Tsai, Y-C; Hsieh, T-S; Marks, JR; Scott, GL; Giovanella, BC; Liu, LF

Published Date

  • June 2008

Published In

Volume / Issue

  • 7 / 6

Start / End Page

  • 1430 - 1439

PubMed ID

  • 18566215

Pubmed Central ID

  • PMC2561335

International Standard Serial Number (ISSN)

  • 1535-7163

Digital Object Identifier (DOI)

  • 10.1158/1535-7163.MCT-07-2345


  • eng

Conference Location

  • United States