Background: This study was designed to determine the pattern and correlation between expression of the HIF-1α transcriptional targets TGM2 and BNIP3 in laryngeal cancer, and investigate the association of BNIP3 and TGM2 with clinical outcome in laryngeal squamous cell carcinoma (SCC) patients receiving postoperative radiotherapy.
Methods: Immunostaining with antibodies specific to BNIP3 and TGM2 was performed in formalin-fixed, paraffin-embedded specimens from 148 laryngeal SCC patients. BNIP3 and TGM2 expression was scored as high or low, based on the number of tumor cells stained and the staining intensity. All patients received postoperative radiotherapy. Patient follow up and clinicopathological data were compared using the Chi-squared test, univariate and multivariate analyses, and survival curves were generated using the Kaplan-Meier method and log-rank test.
Results: The 3, 5 and 10-year overall survival rates (OS) for all patients were 77.7%, 71.6%, 56.4%, respectively. Primary tumor site, T stage, overall stage, lymph-node metastasis, BNIP3 expression and TGM2 expression were significant prognostic factors for OS in univariate analysis. Negative cervical lymph nodes, high BNIP3 expression and low TGM2 expression were independent prognostic factors of improved OS in multivariate analysis. BNIP3 expression correlates with TGM2 expression in laryngeal SCC (P = 0.012).
Conclusions: This study indicates that lymph-node metastasis, BNIP3 expression and TGM2 expression are independent prognostic factors in laryngeal SCC patients receiving postoperative radiotherapy. Further studies are required to investigate how BNIP3 and/or TGM2 influence the prognosis of laryngeal SCC patients treated with postoperative radiotherapy, and to determine how TGM2 and BNIP3 expression are regulated.