Expression of neurotrophin receptors in surgically resected thymic epithelial tumors.
OBJECTIVE
Neurotrophins are known to exert a variety of pleiotropic responses in different target tissues, but little is known about their effect on thymic epithelial tumors. Therefore, we analyzed the expression of neurotrophin receptors in surgically resected thymic epithelial tumors and evaluated their clinical relevance.


METHODS
The expression of neurotrophin receptors (Trk-A, Trk-B, Trk-C and p75(NTR)) in thymic epithelial tumors was evaluated in 99 consecutive patients based on immunohistochemical staining. The pattern of expression was analyzed according to the WHO classification, and survival outcomes were estimated.


RESULTS
Thymic tumors were classified as type A (n=6), AB (n=21), B1 (n=15), B2 (n=24), B3 (n=22) or C (n=11). All tumors, except one type C thymoma, demonstrated cytoplasmic Trk-A immunostaining, and no thymic tumors showed Trk-B or Trk-C immunoreactivity. p75(NTR) immunostaining demonstrated characteristic patterns according to the WHO subtypes of thymomas. All type A and type AB thymomas showed p75(NTR) immunoreactivity, except one type A tumor. The expression of p75(NTR) was negative in 6 patients (40%) with type B1 thymomas, 19 patients (79.2%) with type B2 thymomas, 17 patients (77.3%) with type B3 thymomas and 10 patients (90.9%) with type C thymomas. Tumor-related survival at 5 and 10 years was 95.5 and 89.5%, respectively, in p75(NTR)-positive thymomas and 82.8 and 77.2%, respectively, in p75(NTR)-negative thymomas; however, the differences were not statistically significant (P=0.14).


CONCLUSIONS
Among the neurotrophin receptors examined, the pattern of p75(NTR) expression closely correlated with the WHO subtypes of thymomas. Further study of p75(NTR) expression may aid in understanding the biology of thymic epithelial tumors.
Kim
Dae Joon
DJ
Department of Thoracic and Cardiovascular Surgery, Yonsei University College of Medicine, CPO Box 8044, Seoul 120-752, South Korea.
Yang
Woo-Ick
WI
Kim
Se Hoon
SH
Park
In-Kyu
IK
Chung
Kyung Young
KY
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000032:analysis; D009419:Nerve Tissue Proteins / Q000032:analysis; D011379:Prognosis; D020917:Receptor, trkA / Q000032:analysis; D020813:Receptor, trkB / Q000032:analysis; D020812:Receptor, trkC / Q000032:analysis; D017978:Receptors, Growth Factor / Q000032:analysis; D017475:Receptors, Nerve Growth Factor / Q000032:analysis*; D016019:Survival Analysis; D013945:Thymoma / Q000737:chemistry* / Q000473:pathology / Q000601:surgery; D013950:Thymus Gland / Q000378:metabolism / Q000473:pathology; D013953:Thymus Neoplasms / Q000737:chemistry* / Q000473:pathology / Q000601:surgery
C484065:NGFR protein, human; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D017978:Receptors, Growth Factor; D017475:Receptors, Nerve Growth Factor; D020917:Receptor, trkA; D020813:Receptor, trkB; D020812:Receptor, trkC