Checkpoint Kinase 1 Expression Predicts Poor Prognosis in Nigerian Breast Cancer Patients.

BACKGROUND: Checkpoint kinase 1 (CHEK1), a DNA damage sensor and cell death pathway stimulator, is regarded as an oncogene in tumours, where its activities are considered essential for tumourigenesis and the survival of cancer cells treated with chemotherapy and radiotherapy. In breast cancer, CHEK1 expression has been associated with an aggressive tumour phenotype, the triple-negative breast cancer subtype, an aberrant response to tamoxifen, and poor prognosis. However, the relevance of CHEK1 expression has, hitherto, not been investigated in an indigenous African population. We therefore aimed to investigate the clinicopathological, biological, and prognostic significance of CHEK1 expression in a cohort of Nigerian breast cancer cases. MATERIAL AND METHODS: Tissue microarrays of 207 Nigerian breast cancer cases were tested for CHEK1 expression using immunohistochemistry. The clinicopathological, molecular, and prognostic characteristics of CHEK1-positive tumours were determined using the Chi-squared test and Kaplan-Meier and Cox regression analyses in SPSS Version 16. RESULTS: Nuclear expression of CHEK1 was present in 61% of breast tumours and was associated with tumour size, triple-negative cancer, basal-like phenotype, the epithelial-mesenchymal transition, p53 over-expression, DNA homologous repair pathway dysfunction, and poor prognosis. CONCLUSIONS: The rate expression of CHEK1 is high in Nigerian breast cancer cases and is associated with an aggressive phenotype and poor prognosis.

Clinicopathological and molecular characteristics of Ku 70/80 expression in Nigerian breast cancer and its potential therapeutic implications.

Ku 70/80 is a regulator of the Non-Homologous End Joining (NHEJ) roles in clinicopathological features, and has prognostic significance in breast cancer (BC) in Caucasian populations. However, its significance in the Nigerian BC population, which is characterized by a higher rate of the triple-negative and basal phenotype, p53 mutation rate and BRCA1 deficiency, still needs to be investigated. We hypothesize that Ku70/80 expression shows adverse expression in Nigerian BC and, furthermore, that it is likely to have a therapeutic implication for Black BC management. This study investigated the biological, clinicopathological and prognostic significance of Ku 70/80 expression in a BC cohort from a Nigerian population. Ku 70/80 expression was determined in 188 well-characterized formalin-fixed, paraffin-embedded (FFPE) BC samples using tissue microarray and immunohistochemistry. Ku 70/80 expression was correlated with clinicopathological, molecular and prognostic characteristics of patients. Ku 70/80 was expressed in 113 (60.1%) tumors, and was positively associated with metastatic disease, triple-negative and basal phenotype, BRCA1 down regulators (MTA-1 and ID4), p-cadherin, PI3KCA and p53 expression. It inversely correlated with BRCA1, BRCA2, BARD1 and p27. Ku 70/80 was predictive of breast cancer-specific survival in multivariate analysis, but not of disease-free interval. This study demonstrated that Ku 70/80 expression is associated with triple negativity and down-regulation of the homologous recombination pathway of DNA repair. Therefore, the development of novel drugs to target KU70/80 may improve the patients' outcome in the treatment of Black BC.