Expression of the Transient Receptor Potential Channel C3 Correlates with a Favorable Prognosis in Patients with Adenocarcinoma of the Lung

Background: The cation channels of the transient receptor potential (TRP) superfamily are implicated in cancer formation; in particular, TRPC3 has been shown to contribute to the progression of human ovarian cancer. However, the relationship between TRP expression and the clinicopathological characteristics of lung cancer and patient prognosis is not well understood. Therefore, we investigated the relationship between TRP expression and the prognosis of patients with adenocarcinoma of the lung.

Methods: We used semiquantitative real-time reverse transcription polymerase chain reaction to assess the expression of TRP mRNA in tumor samples from 95 patients with adenocarcinoma of the lung. We then correlated the TRP mRNA levels with clinicopathological factors. We also used immunohistochemical staining to determine the localization of expressed TRP.

Results: The 5-year overall and disease-free survival rates among patients expressing higher levels of TRPC3 mRNA were significantly better than the corresponding rates among patients expressing lower levels (P=0.004, P=0.002, respectively, by log-rank test). Multivariate Cox proportional hazard analyses revealed that tumor size (hazard ratio, 2.46; 95% confidence interval [CI], 1.06 to 5.79; P=0.036), n2 (hazard ratio, 3.81; 95% CI, 1.29 to 11.77; P=0.015) and TRPC3 (hazard ratio, 2.71; 95% CI, 1.33 to 5.59; P=0.006) were independent factors affecting the 5-year overall survival rate. Immunohistochemistry showed that the cytoplasm of tumor cells were stained positively for TRPC3.

Conclusions: Higher levels of TRPC3 expression in tumor cells are an independent predictor of a better prognosis in patients with adenocarcinoma of the lung.