[Expression of Smac in Stage I-II non-small cell lung cancer and its clinical significance].
OBJECTIVE
Second mitochondrial activator of caspase (Smac) was recently identified as a new apoptogenic factor that is released from mitochondria. It promotes apoptosis by antagonizing inhibitor of apoptosis proteins, and shows in vitro antitumor effect. However, little is known about its role in non-small cell lung cancer (NSCLC). This study was to investigate the expression of Smac in stage I-II NSCLC, and explore its correlations to clinicopathologic features and prognosis.


METHODS
Immunohistochemistry and tissue microarray were used to detect the expression of Smac in 213 specimens of stage I-II NSCLC. Its correlations to clinicopathologic features and prognosis of NSCLC were analyzed.


RESULTS
The 5-year survival rate of the patients with stage I NSCLC was 61.9%, and that of the patients with stage II NSCLC was 30.0%. Smac protein was mainly localized in cytoplasm. When the positive cells percentage of 75% was used as a cutoff point, 129 (39.4%) samples showed high Smac expression, and 84 (60.6%) showed low Smac expression. Smac expression was not correlated to sex, age, histological type, blood type and prognosis of the patients, whereas the positive rate of Smac was significantly higher in the patients with lymph node metastasis than in the patients without lymph node metastasis (58.3% vs. 37.0%, P<0.05).


CONCLUSIONS
Smac protein might be correlated to lymph node metastasis of NSCLC.
Zhao
Jin-Ming
JM
State Key Laboratory of Oncology in South China, Guangzhou, Guangdong, 510060, P. R. China.
Zhu
Zhi-Hua
ZH
Wu
Qiu-Liang
QL
Hou
Jing-Hui
JH
Huang
Xiao-Ping
XP
Zhang
Peng-Yuan
PY
Rong
Tie-Hua
TH