Role of overexpression of myeloid cell leukemia-1-long in prognosis of malignant pleomorphic adenoma

Abstract

Objective: To evaluate the clinicopathological significance of the expression of the two myeloid cell leukemia-1 isoforms, myeloid cell leukemia-1-long (Mcl-1L) and myeloid cell leukemia-1-short (Mcl-1S) in malignant pleomorphic adenoma (MPA). Methods: A total of 56 patients with MPA treated with surgery, the expression of Mcl-1L and Mcl-1S were detected by quantitative real-time PCR (qPCR) in mRNA level, and by Western blotting in protein level, respectively. The correlation between clinicopathological parameters (gender, age, site, habits, size, node, metastasis, recurrence) was done using the chi-square test. Kaplan-Merier curve was used to analyze the survival in all patients, Log Rank test was performed to observe the difference between groups. Cox's proportional hazard test was used to identify the factors that were independent predictors of survival. Results: qPCR showed overexpression of Mcl-1L in 66.1%MPA patients (37/56), with significant difference in terms of tumor site, significantly higher expression of Mcl-1L in MPA (parotid gland: 2.21±1.07, sublingual gland: 2.12±1.08, other sites: 1.83±0.81) than benign pleomorphic adenoma tissue (1.00±0.19) (P<0.01). Western blotting analysis showed significantly higher expression of Mcl-1L in MPA (parotid gland: 1.02±0.43, sublingual gland: 0.71±0.29, other sites: 0.70±0.30) than benign pleomorphic adenoma tissue (0.39±0.08) (P<0.01). In malignant pleomorphic adenoma patients, high Mcl-1L expression was significantly associated with node positivity (P=0.045), advanced tumor size (P=0.002). Kaplan-Meier survival line analysis indicated a significantly lower survival time in Mcl-1L higher-expression patients (24.79±9.71) than lower-expression patients (30.59±9.01) (P=0.017). Multivariate analysis indicated Mcl-1L to be an independent prognostic factor for MPA (P=0.002). Conclusions: The studies suggest that overexpression of Mcl-1L is associated with poor prognosis in MPA. Mcl-1L is an independent prognostic factor in malignant pleomorphic adenoma.