Altered expression of mir-21 and PTEN in human laryngeal and hypopharyngeal squamous cell carcinomas

Purpose: The purpose of this study was to examine the expression of mir-21 and phosphatase and tensin homologue (PTEN) in laryngeal squamous cell carcinomas (LSCCs) and hypopharyngeal squamous cell carcinomas (HSCCs), and assess correlations between the two as well as with clinical characteristics of patients. Methods: The expression of mir-21 in tumor and adjacent non-tumor tissues was investigated by real-time RT-PCR. Immunohistochemistry (IHC) was carried out to analyze PTEN protein levels. Results: Mir-21 was up-regulated in LSCCs and HSCCs compared to adjacent non-tumor tissues (P < 0.05), and the up-regulated expression of mir-21 was associated with clinical stage (P = 0.001), T classification (P = 0.007), pathologic differentiation (P = 0.025), and lymph node positivity (P = 0.002). In contrast, PTEN IHC staining was notably weaker in tumor tissues than in matched non-tumor tissues (P < 0.05), and the down-regulated expression of PTEN was correlated with tumor staging (P = 0.025), the extent of tumor (P = 0.017), and lymph node positivity (P = 0.040). Furthermore, the level of mir-21 was reversely correlated with PTEN expression (P = 0.006). Conclusion: mir-21 and PTEN might play important roles in the progression of LSCC and HSCC, the two fcators demonstrating a negative correlation.