Expression levels of apoptosis-related proteins and Ki-67 in nasal NK / T-cell lymphoma.
OBJECTIVE
Nasal natural killer (NK)/T-cell lymphoma is characterized by chemo-resistance, angiodestruction, and aggressive tumor progression. Few studies exist on molecular characteristics of this disease entity.


METHODS
Expression levels of major apoptosis-related proteins Bcl-2, Bcl-x, Mcl-1, Bax, and a proliferative marker Ki-67 were analyzed in 11 nasal NK/T-cell lymphoma cases by immunohistochemical methods. Nine cases were of NK-cell lineage and two cases were of T-cell lineage. For comparison, 12 follicular lymphoma (FL) cases and 16 diffuse large B-cell lymphoma (DLBCL) cases were also studied.


CONCLUSIONS
Bax expression was low in all nasal NK-cell lymphoma cases, which constitute the major population of nasal NK/T-cell lymphoma. Bax expression in nasal NK-cell lymphoma was similar to FL and significantly lower compared with DLBCL. Bcl-2 expression was significantly lower in nasal NK/T-cell lymphoma compared with that of FL and DLBCL. Bcl-x expression was high in all three lymphomas. Two distinct Mcl-1 expression groups existed for nasal NK/T-cell lymphoma (6.2 +/- 5.2% and 59.1 +/- 12.3%, 95% CI). Ki-67 expression was high in nasal NK/T-cell lymphoma, and worse prognostic groups tended to express higher levels of Ki-67. The results suggest a combination of impaired apoptosis and aggressive proliferation in nasal NK/T-cell lymphoma, and may provide explanations for its poor prognosis.
Yasuda
Hajime
H
Division of Hematology, Department of Medicine, Juntendo University School of Medicine, Tokyo.
Sugimoto
Koichi
K
Imai
Hidenori
H
Isobe
Yasushi
Y
Sasaki
Makoto
M
Kojima
Yuko
Y
Nakamura
Shinji
S
Oshimi
Kazuo
K
D000328:Adult; D000368:Aged; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D019394:Ki-67 Antigen / Q000378:metabolism*; D054391:Lymphoma, Extranodal NK-T-Cell / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009669:Nose Neoplasms / Q000378:metabolism*
D051017:Apoptosis Regulatory Proteins; D019394:Ki-67 Antigen