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Hereditary Breast and Ovarian Cancer
Published in Dongyou Liu, Handbook of Tumor Syndromes, 2020
Moreover, tests (not usually recommended as part of a routine breast cancer workup) may be conducted for ploidy and cell proliferation rate. The cells containing normal amount of DNA are described as diploid, and the cells containing abnormal amount of DNA are described as aneuploid. The rate of cancer cell division can be estimated by the S-phase fraction or a Ki-67 test. Ki-67 is a nuclear protein of 359 kDa encoded by Ki-67 gene located on the long arm of chromosome 10 (10q26.2). Ki-67 expression increases with cell growth and is required for maintaining cell proliferation, DNA metabolic process, cellular response to heat, meiosis, and organ regeneration. The cancer cells with a high S-phase fraction or Ki-67 labeling index divide more rapidly, suggesting a more aggressive cancer [21]. Further, S100A14 and S100A16 are recently identified cancer biomarkers that play a potential role in tumor progression. Higher expression levels of S100A14 and S100A16 proteins in breast cancer appear to be significantly associated with a younger age (<60 years), ER-negative status, HER2-positive status, and a poorer prognosis (Figure 30.2) [22].
S100B protein: general characteristics and pathophysiological implications in the Central Nervous System
Published in International Journal of Neuroscience, 2022
Ana Cristina Arrais, Lívia Helena M. F. Melo, Bianca Norrara, Marina Abuquerque B. Almeida, Kalina Fernandes Freire, Acydalia Madruga M. F. Melo, Lucidio Clebeson de Oliveira, Francisca Overlânia Vieira Lima, Rovena Clara G. J. Engelberth, Jeferson de Souza Cavalcante, Dayane Pessoa de Araújo, Fausto Pierdoná Guzen, Marco Aurelio M. Freire, José Rodolfo L. P. Cavalcanti
Structurally, the S100 protein is a dimer composed by two subunits, described primarily as "α" and "β", named "A" and "B" respectively, constituting three isoforms: α-α, α-β and β-β, where the subunits α-β (S100A) and β-β (S100B) are the most common (5). Altogether there are more than 20 small acidic proteins, being 16 S100A (S100A1 - S100A16), besides S100B, S100G, S100P and S100Z (23).