Nucleolar casein kinase 2 alpha as a prognostic factor in patients with surgically resected early-stage lung adenocarcinoma

Lung cancer remains a leading cause of global cancer-related deaths, therefore the identification of prognostic factors for lung cancer is critical. Casein kinase 2 alpha (CK2 alpha) is one of the driver kinases in various cancers, and it was previously demonstrated that CK2 alpha localization was associated with a poor prognosis in invasive breast cancer. In the present study, the importance of CK2 alpha in the nucleolus was explored as a potential prognostic marker for surgically resected early-stage lung adenocarcinoma. The present study included 118 patients who underwent pulmonary lobectomy between 2014 and 2018 in Fukushima Medical University Hospital (Fukushima, Japan), and in whom CK2 alpha localization in tumor samples was assessed by immunohistochemistry. Patient and tumor characteristics, including pathological stage, histological type and histological grade, were analyzed. Recurrence-free survival (RFS) and overall survival were evaluated in relation to nucleolar CK2 alpha staining. CK2 alpha staining in the nucleoli was observed in 50.8% of lung adenocarcinoma tumors. Positive nucleolar CK2 alpha staining was independent of pathological stage, histological type and histological grade. Patients with positive nucleolar CK2 alpha staining exhibited significantly worse RFS compared with patients with negative staining. Multivariate analysis identified nucleolar CK2 alpha staining and lymph node metastasis as independent poor prognostic factors. The results of the present study suggested that nucleolar CK2 alpha staining is a novel and independent prognostic factor in surgically resected early-stage lung adenocarcinoma. These findings indicated the potential of nucleolar CK2 alpha as a predictive biomarker for future recurrence, and a guide to treatment decisions. Further research is required, particularly in understanding the molecular mechanisms linking nucleolar CK2 alpha to recurrence.