OBJECTIVETo explore the RCP protein expression and its clinicopathological significance in laryngeal squamous cell carcinoma (LSCC).

METHODSRCP protein expression in human head and neck squamous cell carcinoma cell lines (NP-69, Tu686, Tu212, M2 and M4) was analyzed by Western blotting. Besides, its expression in 87 cases of LSCC, 18 cases of adjacent epithelial mucosa and 16 cases of vocal cord leukoplakia was detected by immunohistochemistry, and their correlation with clinicopathological parameters and patients' outcome was analyzed.

RESULTSThe NP-69, Tu212 Tu686, M2 and M4 cells showed a gradual increase in the expression of RCP protein. The average relative expression levels of RCP protein in the NP-69, Tu212, Tu686, M2 and M4 cells were 0.05±0.01, 0.38±0.05, 0.63±0.02, 0.84±0.06 and 0.96±0.04, respectively. The same situation occurred in the adjacent mucosa, vocal cord leukoplakia and LSCC. Specifically, only 3 of 18 adjacent mucosa showed a low RCP expression (scored 0-2). Although the 16 cases of vocal cord leukoplakia had a low RCP expression, all their scores ranged from 0 to 3. While in the LSCC specimens, 59 (67.8%) cases demonstrated a high RCP expression (scored 8-15), 18 cases showed a lower RCP expression (scored 4-7), and only 10 cases were scored 2-3. Among the 87 LSCC cases, there were 28 cases (32.2%) of low RCP expression and 59 cases of high RCP expression. All the 18 cases of cancer-adjacent tissues and 16 cases of vocal cord leukoplakia were of low RCP expression. RCP overexpression was significantly associated with T classification, clinical staging, lymph node metastasis and recurrence (P<0.05 for all). Survival analysis revealed that the 5-year survival rate was 40.0% in the patients with high RCP expression and 75.0% in the patients with low RCP expression, the tumor-free 5-year survival rate was 30.7% and 64.0%, respectively, both showing a significant difference between the two subgroups (P<0.05). Univariate analysis revealed that alcohol history; smoking, T classification, clinical staging, lymph node metastasis and RCP expression were significantly associated with a poor prognosis (P<0.05 for all). The multivariate analysis showed that only recurrence and RCP expression were independent prognostic factors affecting the prognosis for patients with LSCC (P<0.05 for both).

CONCLUSIONSExpression of RCP protein may contribute to the malignant progression of LSCC, and may become a novel marker predicting tumor recurrence, cervical lymph node metastasis and prognosis for patients with laryngeal squamous cell carcinoma.