Aberration of epidermal growth factor receptor expression in bone and soft-tissue tumors: protein overexpression, gene amplification and activation of downstream molecules

Abstract

In order to evaluate the involvement of epidermal growth factor receptor, and to analyze the correlation between gene aberration and protein expression in mesenchymal tumors, we examined protein expression by immunohistochemistry in 125 cases of bone and soft-tissue tumors. Furthermore, amplification of epidermal growth factor receptor gene was determined by fluorescence in situ hybridization. Positive immunostaining was found in 23 cases (18.4%). Among these 23 cases, one of malignant fibrous histiocytoma showed the highest degree (3 þ ) of protein overexpression and gene amplification as clusters of hybridization signals, indicating homogeneously staining regions. The second case of malignant fibrous histiocytoma also showed a higher degree (2 þ ) of overexpression and coamplification of the epidermal growth factor receptor gene with the centromeric regions, indicating polysomy of chromosome 7. The levels of expression observed in immunohistochemistry were confirmed by immunoblotting and found to be comparable. Moreover, although expression of phosphorylated epidermal growth factor receptor was detected in those two cases of malignant fibrous histiocytoma, constitutive activation of extracellular signal-related protein kinase 1/2 was not observed, suggesting that activation of epidermal growth factor receptor does not necessarily and constantly lead to signal transduction to the downstream molecules. In the remaining 123 cases, including 21 cases exhibiting weak (1 þ ) immunoreactivity, no gene amplification nor polysomy was found. Collectively, expression of epidermal growth factor receptor was observed not infrequently in mesenchymal tumors, but 'overexpression' is rare and can be attributed to an increase in gene copy number, resulting from amplification or polysomy. Although cases that scored positive for protein expression and/or gene amplification could be qualified candidates for antiepidermal growth factor receptor therapies, further examination of the status of downstream molecules in the signal cascade, such as phosphorylated epidermal growth factor receptor and extracellular signal-related protein kinase 1/2, may be required as the process of therapeutic strategy.

Epithelioid sarcoma expresses epidermal growth factor receptor but gene amplification and kinase domain mutations are rare

“…[14][15][16][17] In two recent studies of bone and soft tissue neoplasms, EGFR expression was noted in approximately 20% of malignant tumors, with no expression documented in benign lesions, suggesting that EGFR is preferentially expressed in sarcomas. 14,15 However, in general, kinase domain mutations in sarcomas are rare. 26,27 Synovial sarcoma, like epithelioid sarcoma, shows morphologic and immunophenotypic features of epithelial differentiation.…”

“…11,12 Interestingly, recent evidence suggests that EGFR expression is not unique to carcinomas but may be present in malignant bone and soft tissue tumors, with a small subset showing aberrant EGFR gene copy number and/or mutations in the tyrosine kinase domain. [13][14][15][16][17][18] However, the expression, amplification and mutation status of epithelioid sarcoma remains to be characterized.…”

EGFR-dependent and independent activation of Akt/mTOR cascade in bone and soft tissue tumors

“…4 There are a growing number of reports describing protein over-expression, gene amplification, and mutation of EGFR in bone and soft tissue tumors. Immunohistochemical analyses by us and others have shown the expression of EGFR in approximately 60% [5][6][7] and the EGFR phosphorylation (activation) in 27%. 7 Furthermore, point mutations in the tyrosine kinase domain, a critical determinant of Gefitinib sensitivity, were found in 13% of the cases.…”

“…PI3-K, phosphatidylinositol 3-kinase (PI3-K); TSC, tuberous sclerosis complex proteins 1 and 2; mTOR, mammalian target of rapamycin; 4E-BP1, eukaryotic initiation factor 4E-binding protein 1. amplification by fluorescence in situ hybridization analysis, as described earlier. 5,7 Therefore, the 12 newly obtained samples were also evaluated for their EGFR status by exactly identical methods and further used for other additional experiments performed in this study.…”

EGFR and gastrointestinal stromal tumor: an immunohistochemical and FISH study of 82 cases

“…The role of EGFR has been studied in several types of human sarcomas, [22][23][24][25][26][27][28][29][30] mainly in synovial sarcomas. 14,23,29 On the other hand, very few reports about the relationship between GIST and EGFR have been published so far.…”