Molecular characteristics and prognostic features of breast cancer in Nigerian compared with UK women.

Although breast cancer (BC) incidence is lower in African-American women compared with White-American, in African countries such as Nigeria, BC is a common disease. Nigerian women have a higher risk for early-onset, with a high mortality rate from BC, prompting speculation that risk factors could be genetic and the molecular portrait of these tumours are different to those of western women. In this study, 308 BC samples from Nigerian women with complete clinical history and tumour characteristics were included and compared with a large series of BC from the UK as a control group. Immunoprofile of these tumours was characterised using a panel of 11 biomarkers of known relevance to BC. The immunoprofile and patients' outcome were compared with tumour grade-matched UK control group. Nigerian women presenting with BC were more frequently premenopausal, and their tumours were characterised by large primary tumour size, high tumour grade, advanced lymph node stage, and a higher rate of vascular invasion compared with UK women. In the grade-matched groups, Nigerian BC showed over representation of triple-negative and basal phenotypes and BRCA1 deficiency BC compared with UK women, but no difference was found regarding HER2 expression between the two series. Nigerian women showed significantly poorer outcome after development of BC compared with UK women. This study demonstrates that there are possible genetic and molecular differences between an indigenous Black population and a UK-based series. The basal-like, triple negative and BRCA1 dysfunction groups of tumours identified in this study may have implications in the development of screening programs and therapies for African patients and families that are likely to have a BRCA1 dysfunction, basal like and triple negative.

Clinicopathological and molecular significance of Sumolyation marker (ubiquitin conjugating enzyme 9 (UBC9)) expression in breast cancer of black women.

The majority of breast cancers (BC) in Nigerian women are triple negative and show breast cancer-associated gene 1 (BRCA1) deficiency as well as the basal like phenotype, with a high mortality rate. In contrast to the well-defined predictive factors for the hormonal therapy, there is a paucity of information on the BRCA1 deficiency breast tumor biology, particularly among African women. BRCA1 Sumoylation (UBC9) has been speculated to be involved in the ER transcription activity, BRCA1 deficiency and triple negative BC. We therefore hypothesized that UBC9, a SUMOylation marker, may have contributed to the aggressive nature of BRCA1 tumor phenotype observed in Nigerian women. This study investigated the immunoprofiles of UBC9 in tissue microarray (TMA) of 199 Nigerian women and correlated their protein expression with clinical outcome, pathological responses and the expression of other biomarkers to demonstrate the functional significance in Nigerian women. The protein expression of UBC9, as compared with other biomarkers, showed an inverse correlation with steroid hormones (ER, progesterone (PgR)), BRCA1, p27, p21 and MDM4, and a positive correlation with triple negative, basal cytokeratins (CK14 and CK5/6), epidermal growth factor receptor (EGFR), basal-like breast cancer phenotype, p53, phosphoinositide-3-kinases (PI3KCA), placental cadherin, (P-cadherin) and BRCA1 regulators (metastasis tumor antigen-1 (MTA1). Survival analysis showed that those tumors positive for UBC9 expression had a significantly poorer breast cancer-specific survival (BCSS) as compared with those showing negative expression. UBC9 remained an independent predictor of outcome for BCSS. This study demonstrates that UBC9 appears to play an important role in the tumor biology of Nigerian women. Therefore, a novel UBC9 targeted therapy in black women with BC could enhance a better patient outcome.