OBJECTIVE: We investigated whether the expression of mammalian target of rapamycin (mTOR) pathway components is associated with clinicopathologic characteristics and patient outcome in lung adenocarcinoma (AC) and squamous cell carcinoma (SCC). METHODS: We used immunohistochemistry to evaluate the expression of phosphorylated Akt (pAkt), mTOR, p70 ribosomal protein S6 kinase (p70S6K) and phosphatase and tensin homolog deleted on chromosome 10 (PTEN) in 91 cases of AC and 154 cases of SCC. RESULTS: pAkt expression was positively correlated with the expression of mTOR (p < 0.001) and p70S6K (p < 0.001), and mTOR expression was positively correlated with p70S6K expression (p < 0.001). PTEN expression was inversely correlated with the expression of pAkt (p = 0.001), mTOR (p < 0.001) and p70S6K (p = 0.012). In addition, loss of PTEN expression, observed in 37.4% (34/91) of AC patients, was significantly associated with a higher histologic grade (p = 0.013), pathologic T stage (p = 0.016) and N stage (p < 0.001) and advanced TNM stage (p = 0.001), as well as a shorter overall survival of AC patients (p = 0.015). CONCLUSION: The high prevalence of PTEN loss and its association with aggressive tumor behavior and poor patient outcome in AC suggest that loss of PTEN expression is involved in AC progression and serves as a prognostic marker for patients with AC.
OBJECTIVE: We investigated whether the expression of mammalian target of rapamycin (mTOR) pathway components is associated with clinicopathologic characteristics and patient outcome in lung adenocarcinoma (AC) and squamous cell carcinoma (SCC). METHODS: We used immunohistochemistry to evaluate the expression of phosphorylated Akt (pAkt), mTOR, p70 ribosomal protein S6 kinase (p70S6K) and phosphatase and tensin homolog deleted on chromosome 10 (PTEN) in 91 cases of AC and 154 cases of SCC. RESULTS: pAkt expression was positively correlated with the expression of mTOR (p < 0.001) and p70S6K (p < 0.001), and mTOR expression was positively correlated with p70S6K expression (p < 0.001). PTEN expression was inversely correlated with the expression of pAkt (p = 0.001), mTOR (p < 0.001) and p70S6K (p = 0.012). In addition, loss of PTEN expression, observed in 37.4% (34/91) of AC patients, was significantly associated with a higher histologic grade (p = 0.013), pathologic T stage (p = 0.016) and N stage (p < 0.001) and advanced TNM stage (p = 0.001), as well as a shorter overall survival of AC patients (p = 0.015). CONCLUSION: The high prevalence of PTEN loss and its association with aggressive tumor behavior and poor patient outcome in AC suggest that loss of PTEN expression is involved in AC progression and serves as a prognostic marker for patients with AC.