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Int J Clin Exp Pathol 2010;3(6):600-607

Original Article
p16INK4a expression in basal-like breast carcinoma

Olga L. Bohn, Mariana Fuertes-Camilo, Leticia Navarro, Jesus Saldivar, Sergio Sanchez-Sosa

Departments of Pathology, MetroHealth Medical Center-Case Western Reserve University, Cleveland, OH, USA; Department of Pathology,
UPAEP University Hospital-Grupo Christus Muguerza, Puebla, Mexico.

Received June 7, 2010, accepted June, 2010, available online June, 2010

Abstract: BLBC represents a distinctive group of invasive breast carcinomas with specific genotype and immunoprofile. BLBC is usually
defined by gene expression profiling and is currently associated with poor outcome. BLBCs are estrogen receptor (ER) negative, progesterone
receptor (PgR) negative, HER2 negative, and usually show a variable expression of basal cytokeratins (CKs), EGFR and CD117. p16 INK4a is
a tumor suppressor protein, encoded by the CDKN2A gene, which regulates cell cycle.  The reported association of abnormalities in the
p16/Rb pathway with increased risk of malignancy prompted us to determine the expression of p16INK4a in a group of BLBC; the results were
compared with a group of high-grade invasive carcinoma (HG-IC) of breast. Tissue microarrays (TMA) were constructed in triplicate including
18 BLBC and 18 HG-IC. All BLBC cases were ER-/PgR-/HER2-. Seventeen (94%) BLBC were CK 5/6+/CK 14+; 14 (78%) BLCB showed EGFR
expression and 13 (72%) were CD117 positive. BLBCs showed a strong positive reaction with p16 INK4a antibody in 16 of 18 (89%) cases.
Although the significance of p16 INK4a expression in breast cancer is not fully understood, we have shown that p16INK4a is strongly
expressed in breast cancers with basal-like phenotype. Since it is known that p16INK4a is associated with aggressive behavior in human
carcinomas, these data suggest that p16INK4a play a role in the poor prognosis of BLBC. (IJCEP1006002).

Key words: Breast cancer, basal cancer, immunohistochemistry, HER2, estrogen receptor, progesterone receptor, p16 INK4a

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Address all correspondence to:
Olga L. Bohn, MD
Department of Pathology, MetroHealth Medical Center
Case Western Reserve University
2500 MetroHealth Drive,
Cleveland, OH 44109