RESUMO
【Objective】 To explore the expression of checkpoint kinase 2 (CHEK2) in clear cell renal cell carcinoma (ccRCC), its association with the clinicopathological features and prognosis, and to predict its relevant molecular signaling pathways and biological functions. 【Methods】 The gene expression data, phenotype data, and corresponding survival information of ccRCC patients were downloaded from TCGA database. The optimal cutoff value of CHEK2 was determined with the "survminer" package. The patients were divided into low and high expression groups, and the association between CHEK2 expression and clinicopathological features was analyzed. The correlation between CHEK2 expression and ccRCC prognosis was evaluated with univariate and multivariate Cox proportional hazard models. The changes of cell signaling pathways involved in different CHEK2 expression levels were explored with gene set variation analysis (GSVA). The correlation between CHEK2 and immune cell infiltration as well as immune checkpoint molecular expression was analyzed. 【Results】 CHEK2 expression was significantly higher in ccRCC tissues than in normal tissues (P<0.01). Higher level of CHEK2 was significantly associated with higher T stage of ccRCC (P<0.01). Kaplan-Meier analysis showed overall survival (OS) of patients with high CHEK2 expression were notably decreased (P<0.001). Univariate and multivariate analyses revealed CHEK2 expression as an independent risk factor of survival (HR=1.950, 95%CI: 1.490-2.570, P<0.001; HR=1.588, 95%CI: 1.185-2.127, P=0.002). GSVA showed that CHEK2 was involved in the following pathways: proximal tubule bicarbonate reclamation, propanoate metabolism, limonene and pinene degradation, fatty acid metabolism, primary immunodeficiency, systemic lupus erythematosus, p53 signaling pathway, homologous recombination, DNA replication and mismatch repair. Correlation analysis suggested that CHEK2 was associated with increased infiltration of multiple immune cells in ccRCC and upregulation of various immune checkpoint molecules. 【Conclusion】 The high level of CHEK2 in ccRCC is an independent predicting factor for poor prognosis. It is probably involved in regulating related events of tumor immune infiltration and may become a new target for ccRCC therapy.
RESUMO
Abstract: Tobacco smoking involves a high risk of human malignancies, including oral cancer, because it contains multiple carcinogens that cause genetic instability. Thus, a worse prognosis would be expected for cancer patients who are smokers. The aim of this study was to assess the DNA damage response through the expression of checkpoint kinase 2 (CHK2), H2A histone family member X (H2AX), and P53 among smokers and non-smokers with oral squamous cell carcinoma (OSCC). Associations between immunoexpression of proteins and clinicopathological data and histopathological grading were also analyzed. A total of 35 individuals (18 non-smokers and 17 smokers) with OSCC of the tongue and/or floor of the mouth were included. Immunohistochemistry for H2AX was conducted for the identification of double-strand breaks, CHK2, and P53 to evaluate the expression of this protein in cell cycle regulation. The sample consisted of 22 males and 13 females, with a mean age of 63.9±11.8 years. OSCC of non-smokers were well-differentiated tumors in 50% of the cases, and those of smokers were equally distributed into moderately differentiated and poorly differentiated tumors (35.3% each). Overall, 31 (88.6%) cases were CHK2-positive, 27 (77.1%) were H2AX-positive, and 23 (65.7%) were P53-positive, with no difference between smokers and non-smokers (p > 0.05). No association was found between proteins and clinicopathologic data (p > 0.05). Similarities in CHK2, H2AX, and P53 immunohistochemical staining patterns were observed between smokers and non-smokers, and immunoexpression was not associated with clinicopathological parameters. However, the findings indicated consistent expression of these proteins in OSCC.
RESUMO
Background: Oral squamous cell carcinoma (OSCC) is the most frequently occurring malignant tumor of the head and neck region. Chk2 (Checkpoint kinase 2) is considered a tumor suppressor gene that acts on the cellular response to DNA damage. However, the role of Chk2 in OSCC prognosis is not yet fully understood. The objective of this study was to evaluate Chk2 immunoexpression in OSCC and to elucidate the association between its expression and clinicopathological parameters of prognostic importance, including overall survival, disease-free survival, and metastasis-free survival. Methods: Chk2 expression was analyzed in 101 samples from patients with OSCC using immunohistochemistry. We stratified the patients into high expression (> 66% of cells positive for Chk2) and low expression (< 66%) groups. Results: Chk2 showed high expression in 57.43% of OSCC. In our study, the expression of Chk2 did not correlate with any of the prognostic parameters evaluated. There was no difference between overall survival, metastasis-free survival, and disease-free survival according to Chk2 expression. Conclusion: Despite the great importance of Chk2 in the development of different types of cancer, our findings do not favor Chk2 as a prognostic marker in oral squamous cell carcinoma.