Significance of Karyopherin-α 2 (KPNA2) Expression in Esophageal Squamous Cell Carcinoma

Background: Karyopherin-alpha 2 (KPNA2) is a member of the importin a family and has recently been reported to play an important role in tumorigenesis and tumor progression. The aim of the current study was to elucidate the clinicopathological significance of immunohistochemical expression of KPNA2 in esophageal squamous cell carcinoma (ESCC). Patients and Methods: KPNA2 expression was investigated by immunohistochemistry in 116 surgically resected ESCC, and the association of KPNA2 expression with clinicopathologic features was also examined. Results: Sixty (51.7%) ESCCs demonstrated positive expression of KPNA2. Positive expression of KPNA2 showed a significant association with poor differentiation (p=0.015), tumor depth (p=0.001), lymphatic invasion (p<0.001), venous invasion (p<0.001), and tumor stage (p=0.008). Positive expression of KPNA2 was also significantly associated with Ki-67 labeling index (p=0.039). Univariate analysis revealed that the prognosis of the ESCC patients whose tumors demonstrated positive expression of KPNA2 was significantly poorer than that of those that did not (p=0.009). Multivariate analysis revealed that only tumor depth and the presence of lymph node metastasis, which are strong prognostic factors in ESCC, were independently associated with poor prognosis in this study. Conclusion: KPNA2 expression is associated with poor differentiation, tumor invasiveness, and tumor proliferation in ESCC.