TIMP‑1 Increases Expression and Phosphorylation of Proteins Associated with Drug Resistance in Breast Cancer Cells

Tissue inhibitor of metalloproteinase
1 (TIMP-1) is a protein with
a potential biological role in drug resistance. To elucidate the unknown
molecular mechanisms underlying the association between high TIMP-1
levels and increased chemotherapy resistance, we employed SILAC-based
quantitative mass spectrometry to analyze global proteome and phosphoproteome
differences of MCF-7 breast cancer cells expressing high or low levels
of TIMP-1. In TIMP-1 high expressing cells, 312 proteins and 452 phosphorylation
sites were up-regulated. Among these were the cancer drug targets
topoisomerase 1, 2A, and 2B, which may explain the resistance phenotype
to topoisomerase inhibitors that was observed in cells with high TIMP-1
levels. Pathway analysis showed an enrichment of proteins from functional
categories such as apoptosis, cell cycle, DNA repair, transcription
factors, drug targets and proteins associated with drug resistance
or sensitivity, and drug transportation. The NetworKIN algorithm predicted
the protein kinases CK2a, CDK1, PLK1, and ATM as likely candidates
involved in the hyperphosphorylation of the topoisomerases. Up-regulation
of protein and/or phosphorylation levels of topoisomerases in TIMP-1
high expressing cells may be part of the mechanisms by which TIMP-1
confers resistance to treatment with the widely used topoisomerase
inhibitors in breast and colorectal cancer.