1. p16 Immunohistochemical Patterns in Triple-Negative Breast Cancer: Clinical and Genomic Similarities of the p16 Diffuse Pattern to pRB Deficiency.
- Author
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Lee, Miseon, Lee, Ahwon, Choi, Byung-Ock, Park, Woo-Chan, Lee, Jieun, and Kang, Jun
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TRIPLE-negative breast cancer , *HOMOLOGOUS recombination , *RETINOBLASTOMA protein , *MOSAICS (Art) , *CELL cycle - Abstract
Triple-negative breast cancer (TNBC) is associated with alterations in the retinoblastoma pathway. As a consequence of retinoblastoma protein (pRB) loss, compensatory upregulation of p16 occurs due to the loss of phosphorylated pRB-mediated negative feedback on p16 expression. The aim of this study is to investigate the clinicopathological and genomic characteristics associated with the diffuse pattern of p16 immunohistochemistry (IHC) in TNBC.Introduction: The study analyzed surgically resected TNBC for whole-exome sequencing in 113 cases and for cDNA microarray in 144 cases. The p16 IHC results were classified into two patterns: diffuse and negative/mosaic.Methods: In the entire cohort (Results: n = 257), the diffuse pattern of p16 IHC was observed in 123 (47.9%) patients and the negative/mosaic pattern in 134 (52.1%). Biallelic RB1 inactivation was observed in 14.3% of patients with the diffuse pattern. The diffuse pattern of p16 IHC showed more frequent RB1 alterations and cell cycle progression signatures, a higher Ki-67 labeling index, more frequent chromosome segment copy number changes, a higher frequency of homologous recombination deficiency high, and immune-related signatures.PIK3CA mutations were more frequent in the negative/mosaic pattern.CCND1 amplification was identified in 5 cases, all with the negative/mosaic pattern. In TNBC, the diffuse p16 pattern shows clinical and genomic similarities to pRB-deficient tumors, suggesting shared characteristics. This suggests that p16 IHC testing may provide new therapeutic approaches, underscoring its potential clinical importance. [ABSTRACT FROM AUTHOR]Conclusion: - Published
- 2024
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