Predicting dedifferentiation in liposarcoma: a proteomic approach.

[dedifferentiated liposarcoma]

There are no known morphologic characteristics , cytogenetic aberrations , or molecular alterations predictive of dedifferentiation in liposarcomas . Identification of such a prognostic marker could potentially affect surgical and adjuvant therapy and /or follow-up surveillance for these patients . Two -dimensional difference gel electrophoresis was utilized to characterize protein expression patterns in lipoma , atypical lipomatous tumor (ALT ), and the well-differentiated components of dedifferentiated liposarcoma (DDL ). Protein spots were identified by peptide mapping /fingerprinting using matrix-assisted laser desorption ionization time-of-flight mass spectrometry . No significant differences in protein expression were identified between lipoma and ALT or DDL . Proteins that were significantly down-regulated in the well-differentiated component of DDL compared to ALT included mitochondrial aldehyde dehydrogenase 2 (ALDH 2 , >3 -fold reduction ) and selenium-binding protein-1 (SELENBP 1 , >4 -fold reduction ). Subsequent validation studies were performed by immunohistochemistry (IHC ) on a separate series of ALT (n = 30 ) and the well-differentiated components of DDL (n = 28 ). IHC stains were evaluated in a semi-quantitative manner , and the results were analyzed using the Mann-Whitney test and receiver-operator curve analysis . Decreased IHC staining for SELENBP 1 in the well-differentiated component of DDL was confirmed . Cytoplasmic ALDH 2 levels determined by IHC were not significantly different in ALT and DDL ; no nuclear staining for ALDH 2 was observed . Expression of SELENBP 1 is decreased in the well-differentiated component of DDL compared to ALT . However , variability in the staining patterns in liposarcoma precludes its use as a predictive marker for dedifferentiation .