ABSTRACT
Cancer progression is governed by multifaceted interactions of cancer cells with their microenvironment and one of these ways is through secreted compounds. Substances released by gastric cancer cells have not being profiled in a proteome-wide manner. ITRAQ-based tandem mass spectrometry was employed to quantify proteins secreted by HFE145 normal, MKN7 well-differentiated, and MKN45 poorly differentiated gastric cancer cell lines. The expression levels of 237 proteins were found to be significantly different between normal and cancer cells. Further examination of 16 gastric cell lines and 115 clinical samples validated the up-regulation of CTSS expression in gastric cancer. Silencing CTSS expression suppressed the migration and invasion of gastric cancer cells in vitro. Subsequent secretomics revealed that CTSS silencing resulted in changes in expression levels of 197 proteins, one-third of which are implicated in cellular movement. Proteome-wide comparative secretomes of normal and gastric cancer cells were produced that constitute a useful resource for gastric cancer research. CTSS was demonstrated to play novel roles in gastric cancer cell migration and invasion, putatively via a network of proteins associated with cell migration, invasion, or metastasis. Cathepsin S is member of a large group of extracellular proteases, which are attractive drug targets. The implicated role of CTSS in gastric cancer metastasis provides an opportunity to test existing compounds against CTSS for adjuvant therapy and/or treatment of metastatic gastric cancers.
Subject(s)
Cathepsins/metabolism , Cell Movement/physiology , Neoplasm Proteins/metabolism , Stomach Neoplasms/metabolism , Stomach Neoplasms/pathology , Cathepsins/chemistry , Cell Line, Tumor , Humans , Isotope Labeling , Neoplasm Invasiveness , Neoplasm Proteins/chemistry , Proteomics/methods , Reproducibility of Results , Signal Transduction , Tandem Mass SpectrometryABSTRACT
Aurora kinases have evolved as a new family of mitotic centrosome- and microtubule-associated kinases that regulate the structure and function of centrosomes and spindle. One of its members, Aurora-A, is a potential oncogene. Overexpression of Aurora-A is also implicated in defective centrosome duplication and segregation, leading to aneuploidy and tumorigenesis in various cancer cell types. However, the regulatory pathways for mammalian Aurora-A are not well understood. Exploiting the lethal phenotype associated with the overexpression of Aurora-A in yeast, we performed a dosage suppressor screen in yeast and report here the identification of a novel negative regulator of Aurora-A, named AIP (Aurora-A kinase Interacting Protein). AIP is a ubiquitously expressed nuclear protein that interacts specifically with human Aurora-A in vivo. Ectopic expression of AIP with Aurora-A in NIH 3T3 and COS cells results in the down-regulation of ectopically expressed Aurora-A protein levels, and this down-regulation is demonstrated to be the result of destabilization of Aurora-A through a proteasome-dependent protein degradation pathway. A noninteracting deletion mutant of AIP does not down-regulate Aurora-A protein, suggesting that the interaction is important for the protein degradation. AIP could therefore be a potential useful target gene for anti-tumor drugs.
