Comparative proteome analysis of gonadal and extragonadal germ cell tumors

Abstract

14530 Background: Germ cell tumors (GCTs) are the most common malignancy in young Caucasian males aged 20–40. Even though highly effective treatment strategies have been developed for the majority of patients (pts) with GCT, long term survival rate in pts with primary mediastinal non-seminomas nowadays remains below 50%. The molecular mechanism underlying the increased resistance to treatment remains elusive. Therefore, a systematic approach of global proteome analysis was used as a screening tool to compare GCT cell lines of gonadal and extragonadal origin. Methods: Comparative protein expression analysis of two GCT cell lines, NTERA2 (of gonadal origin) and NCCIT (of mediastinal origin) was performed using 2-dimensional gelelectrophoresis. Differentially expressed proteins were analyzed using matrix-assisted laser desorption/ionization - time of flight mass spectrometry (MALDI-TOF). Identification of proteins was performed using peptide mass-fingerprinting and NCBI/SwissProt database search. Results: On average, 761 spots on each gel were detected. Of these, 66 proteins were found to be differentially expressed in an at least in 2-fold manner. Expression of 47 proteins was found to be higher in NCCIT than in NTERA2, 19 proteins showed lower expression in NCCIT than in NTERA2. All 66 spots were analyzed, and 35 (51%) proteins were positively identified by peptid mass fingerprinting and database search. These proteins could be grouped into different categories: 9 are involved in metabolism, 5 each in protein folding and DNA-binding/transcription, 4 in cytoskeleton/cell movement, 3 in cell signaling/differentiation, and 1 each in ion transport and membrane/vesicle trafficking. Of 7 proteins, the function is currently unknown. Conclusions: This analysis demonstrates that proteomic tools are valuable in studying similarities and differences between gonadal and primary extragonadal GCTs. Further characterization and functional analysis of selected proteins is ongoing, with special emphasis on factors potentially involved in treatment resistance and sensitivity. Furthermore, the acquired proteome map of untreated cells will help to identify cellular changes occuring under different experimental conditions in vitro like induction of differentiation and response to cytotoxic treatment. No significant financial relationships to disclose.