Expression of metastasis-associated protein 1 (MTA1) is significantly associated with the progression of oral squamous cell carcinoma in Taiwan
Overexpression of metastasis-associated protein 1 (MTA1) has been found to be significantly associated with the progression or prognosis of some human cancers. The purpose of this study was to assess whether expression of MTA1 protein is associated with the progression, recurrence, and prognosis of oral squamous cell carcinoma (OSCC) in Taiwan. We used an immunohistochemical technique to examine the expression of MTA1 protein in 74 specimens of OSCC, 100 specimens of oral epithelial dysplasia (OED; 33 mild, 44 moderate, and 23 severe OED cases), and 21 specimens of normal oral mucosa (NOM). The cytoplasmic and nuclear MTA1 labeling indices (LIs) in OSCC, OED, and NOM samples were calculated and compared between groups. The correlation between the cytoplasmic or nuclear MTA1 LI in OSCCs and clinicopathological parameters or survival of OSCC patients was analyzed statistically. The mean cytoplasmic MTA1 LIs were all over 95% for NOM, OED and OSCC samples. There was no significant association of the cytoplasmic MTA1 LI with any of the clinicopathological parameters of OSCC patients. The mean nuclear MTA1 LIs decreased significantly from NOM (73±13%) through mild OED (71±16%), moderate OED (60±22%), and severe OED (46±25%) to OSCC samples (30±30%, P=0.000). A significant correlation was found between the lower mean nuclear MTA1 LIs and OSCCs located at the buccal mucosa and tongue (P=0.001), with larger tumor sizes (T3 and T4, P=0.020), with regional lymph node metastases (N1, N2 and N3, P=0.024), or with more advanced clinical stages (stages 3 and 4, P=0.045). Our results suggest that the MTA1 is universally expressed in the cytoplasm of normal, dysplastic and malignant oral epithelial cells. The nuclear expression of MTA1 significantly reduced from NOM through OED to OSCC samples, and is inversely related to T status, N status, and clinical staging of OSCCs. Therefore, the nuclear MTA1 LI can be used to predict the progression of OSCCs in Taiwan.