Proteomics of uveal melanomas suggests HSP-27 as a possible surrogate marker of chromosome 3 loss.
OBJECTIVE
To compare the proteomic profiles of primary uveal melanomas, with and without loss of chromosome 3.


METHODS
Frozen specimens from three uveal melanomas with disomy 3 and from four tumors with monosomy 3, according to fluorescence in situ hybridization (FISH) analysis, were subjected to high-resolution, two-dimensional (2-D) gel electrophoresis. The protein expression profiles of the two uveal melanoma cytogenetic groups were compared: Proteins that differed significantly were excised and analyzed by tandem mass spectrometry. Differentially expressed proteins were further analyzed with Western blot analysis. An independent cohort of 41 formalin-fixed, paraffin-embedded (FFPE) uveal melanomas, whose chromosome 3 status had been determined by multiplex ligation-dependent probe amplification (MLPA), was examined for the appropriate antigens by immunohistochemistry.


RESULTS
Four protein spots were 1.5-fold (Student's t-test, P < 0.05) differentially expressed in the two uveal melanoma types: two spots were overexpressed in the disomy 3 group compared with the monosomy 3 group, whereas two spots were underexpressed. Identification of the four spots yielded nine proteins. Western blot analysis confirmed the results for heat shock protein (HSP)-27, vimentin, and pyruvate dehydrogenase beta (PDHB), with a statistical significance for the first two proteins. HSP-27 was significantly downregulated, whereas vimentin was upregulated in the monosomy 3 tumors (Student's t-test, P = 0.003 and P = 0.005, respectively). Immunohistochemistry confirmed low-to-negative HSP-27 protein expression in monosomy 3 uveal melanomas (Student's t-test; P = 0.011).


CONCLUSIONS
Low-to-negative HSP-27 protein expression in uveal melanoma correlates strongly with monosomy 3. Further validation is necessary to determine whether immunohistochemical assessment of HSP-27 expression correlates with metastatic mortality.
Coupland
Sarah E
SE
Department of Pathology, School of Cancer Studies, University of Liverpool, Liverpool, United Kingdom. s.e.coupland@liverpool.ac.uk
Vorum
Henrik
H
Mandal
Nakul
N
Kalirai
Helen
H
Honoré
Bent
B
Urbak
Steen Fiil
SF
Lake
Sarah L
SL
Dopierala
Justyna
J
Damato
Bertil
B
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000378:metabolism*; D015153:Blotting, Western; D002893:Chromosomes, Human, Pair 3 / Q000235:genetics*; D015180:Electrophoresis, Gel, Two-Dimensional; D005260:Female; D055551:HSP27 Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D007124:Immunoenzyme Techniques; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D008545:Melanoma / Q000235:genetics* / Q000378:metabolism*; D008875:Middle Aged; D009006:Monosomy; D040901:Proteomics; D014604:Uveal Neoplasms / Q000235:genetics / Q000378:metabolism*; D014746:Vimentin / Q000378:metabolism
D014408:Biomarkers, Tumor; D055551:HSP27 Heat-Shock Proteins; D014746:Vimentin