Low claudin-6 expression correlates with poor prognosis in patients with non-small cell lung cancer.
OBJECTIVE
Claudins are found in junctional complexes mediating cell adhesion and are involved in the attachment of tight junctions to the underlying cytoskeleton. Abnormal claudin-6 expression has been observed for a variety of malignant solid tumors, but the expression of claudin-6 in non-small cell lung cancer (NSCLC) has not yet been characterized.


METHODS
Immunohistochemistry, reverse transcription-polymerase chain reaction (RT-PCR), and western blot analysis were used to quantify claudin-6 expression in 123 cases of NSCLC and non-cancerous adjacent tissue. We analyzed the relationship between claudin-6 expression and clinicopathological features of NSCLC. The Kaplan-Meier method was used to analyze postoperative survival rates, and the log-rank test was used to assess differences in survival rates. The Cox regression model was used to perform multivariate analysis.


RESULTS
Claudin-6 expression was low for 61 of 123 (49.6%) NSCLC tissue samples and for 33 of 123 (26.8%) normal adjacent tissue samples. RT-PCR and western blot analyses confirmed the immunohistochemistry results. Claudin-6 expression was associated with lymph node metastasis (P<0.001) and TNM stage (P=0.007). Kaplan-Meier analysis indicated that patients with low claudin-6 expression had significantly lower survival rates than those with high claudin-6 expression. Multivariate analysis suggested that low claudin-6 expression was an independent indicator of prognosis in NSCLC patients.


CONCLUSIONS
Low claudin-6 expression is an independent prognostic biomarker that indicates a worse prognosis in patients with NSCLC.
Department of Thoracic Oncology, The Affiliated Tumor Hospital of Xinjiang Medical University, Urumqi, Xinjiang Province, People's Republic of China.
Qiang
Q
Wang
Department of Thoracic Oncology, The Affiliated Tumor Hospital of Xinjiang Medical University, Urumqi, Xinjiang Province, People's Republic of China.
Yan
Y
Zhang
Department of Oncology, First Hospital of Lanzhou University, Lanzhou, Gansu Province, People's Republic of China.
Tao
T
Zhang
Department of Thoracic Oncology, The Affiliated Tumor Hospital of Xinjiang Medical University, Urumqi, Xinjiang Province, People's Republic of China.
Zhi-Gang
ZG
Han
Department of Thoracic Oncology, The Affiliated Tumor Hospital of Xinjiang Medical University, Urumqi, Xinjiang Province, People's Republic of China.
Li
L
Shan
NSCLC; RT-PCR; claudin-6; immunohistochemistry; western blot