bcl-2 overexpression in
synovial sarcomas has been recently reported. Although it is widely known that bcl-2 suppresses apoptosis in various cells, there are no studies that have examined the significance of apoptosis in
synovial sarcoma. In the present study, we visualized apoptotic
tumor cells by the
terminal deoxynucleotidyl transferase-mediated
deoxyuridine triphosphate in situ nick end-labeling (TUNEL) method in 49 cases of primary
synovial sarcoma. The degree of apoptosis was analyzed in relation to several clinicopathologic parameters, cell proliferative activity, and immunohistochemical expression of apoptosis-related
proteins, including bcl-2, bax, bcl-x, bak, p53, p21 (WAF1/CIP1), Fas, and
Fas ligand. TUNEL index (TUNEL-I) significantly correlated with the mitotic index (MI) (ñ = 0.60, P < .0001) and Ki-67 labeling index (MIB1-I) (ñ = 0.52, P = 0.0005). There was a highly significant association between high TUNEL-I value (>.8%) and poor prognosis (log-rank test; P < .0001). Many
synovial sarcomas were diffusely positive for bcl-2 family
proteins (bcl-2, bax, bcl-x, and bak) and were negative or only sporadically positive for Fas,
Fas ligand, p53, and p21 (WAF1/CIP1)
proteins. The results indicated that increased rate of apoptosis in primary
synovial sarcoma was considered to be an
indicator of poor prognosis. In addition, apoptosis in
synovial sarcoma may be controlled by multiple apoptosis-regulating mechanisms, including the bcl-2 family.