Objective: To study the expression of stomatin like protein-2 (SLP-2) at mRNA and protein levels in two kinds of malignant epithelial tumors, including laryngeal squamous cell carcinoma (LSCC) and invasive breast cancer, and to study the relations of SLP-2 expression and clinicopathologic parameters with the prognosis.
Methods: RT-PCR and Western blot were used to detect the expression of SLP-2 mRNA and protein in LSCC and their normal counterparts (46 and 10 pair, respectively). Immunohistochemistry was carried on tissue array constructed from LSCC (104 cases) and breast cancer (263 cases), respectively. The association between SLP-2 expression and clinicopathologic parameters was analyzed.
Results: LSCC showed a higher expression of SLP-2 than that of their normal counterparts (negative expression) at mRNA (83%, 38/46) and protein (7/10) level. Immunohistochemical analysis of LSCC showed that compared with negative expression in normal laryngeal epithelium (0/20), a higher SLP-2 expression was detected in LSCC (36/104, P=0.000) and associated with the advanced clinical stage (P<0.01) and lymph node metastasis (P=0.003). Immunohistochemical study of invasive breast cancer demonstrated that compared with negative expression in normal breast tissue (0/10), more than one half of the cases showed a high SLP-2 expression (52.5%, 138/263, P=0.000) in breast cancer, which correlated with the tumor size (P=0.020), lymph node metastasis (P<0.01), advanced clinical stage (P<0.01), distant metastasis (P=0.002) and HER2/neu protein expression (P=0.037). Survival analysis showed a shorter overall survival probability in patients with a high SLP-2 expression. It was considered that lymph node metastasis, positive HER2/neu expression, and high-level SLP-2 expression may act as the independent prognostic factors for those tumors.
Conclusions: A high expression level of SLP-2 may be associating with the development of invasion and metastasis in LSCC and breast cancer, and SLP-2 is also considered working as an independent factor indicating a poor prognosis clinically in breast cancer.