RESUMO
The aim was to identify mutations in serum cell-free DNA (cfDNA) associated with disease progression on tamoxifen treatment in metastatic breast cancer (MBC). Sera available at start of therapy, during therapy and at disease progression were selected from 10 estrogen receptor (ER)-positive breast cancer patients. DNA from primary tumor and normal tissue and cfDNA from minute amounts of sera were analyzed by targeted next generation sequencing (NGS) of 45 genes (1,242 exons). At disease progression, stop-gain single nucleotide variants (SNVs) for CREBBP (1 patient) and SMAD4 (1 patient) and non-synonymous SNVs for AKAP9 (1 patient), PIK3CA (2 patients) and TP53 (2 patients) were found. Mutations in CREBBP and SMAD4 have only been occasionally reported in breast cancer. All mutations, except for AKAP9, were also present in the primary tumor but not detected in all blood specimens preceding progression. More sensitive detection by deeper re-sequencing and digital PCR confirmed the occurrence of circulating tumor DNA (ctDNA) and these biomarkers in blood specimens.
Assuntos
Antineoplásicos Hormonais/uso terapêutico , Neoplasias da Mama/genética , Ácidos Nucleicos Livres/genética , DNA de Neoplasias/genética , Tamoxifeno/uso terapêutico , Proteínas de Ancoragem à Quinase A/genética , Biomarcadores Tumorais/sangue , Biomarcadores Tumorais/genética , Mama/patologia , Neoplasias da Mama/sangue , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/patologia , Proteína de Ligação a CREB/genética , Ácidos Nucleicos Livres/sangue , Ácidos Nucleicos Livres/isolamento & purificação , Classe I de Fosfatidilinositol 3-Quinases/genética , Proteínas do Citoesqueleto/genética , DNA de Neoplasias/sangue , DNA de Neoplasias/isolamento & purificação , Progressão da Doença , Éxons/genética , Feminino , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Pessoa de Meia-Idade , Polimorfismo de Nucleotídeo Único , Análise de Sequência de DNA , Proteína Smad4/genética , Proteína Supressora de Tumor p53/genéticaRESUMO
Our previous study demonstrated that high mRNA levels for Seven in Absentia Homolog 2 (SIAH2) correlated with high Estrogen Receptor (ER) mRNA levels and with longer progression-free survival (PFS) after first-line tamoxifen. Others showed high SIAH2 protein levels in ER-negative breast cancer associated with an unfavorable relapse-free survival. In the current study, we investigated SIAH2 protein expression to clarify the discrepancy between protein and mRNA findings and to determine its diagnostic value in breast cancer patients. Tissue microarrays (TMAs) containing core specimens of primary breast tumors were immunohistochemically stained for SIAH2 protein. The TMAs analyzed a cohort of 746 patients with primary breast cancer (PBC) and a cohort of 245 patients with ER-positive metastatic breast cancer (MBC) treated with first-line tamoxifen. SIAH2 staining was scored for intensity and proportion of positive tumor cells and evaluated for its relationship with metastasis-free survival (MFS) and PFS. Multivariate survival analyses included traditional prognostic or predictive factors, respectively. The PBC-cohort had 263 patients with high SIAH2 protein expression and decreased expression of ER protein and mRNA levels (P = 0.005 and P = 0.003, respectively). High SIAH2 levels correlated with significant unfavorable MFS in lymph node negative, ER-positive breast cancer patients. The MBC-cohort had 86 patients with increased SIAH2 protein expression. High SIAH2 expression was associated with an unfavorable PFS after first-line tamoxifen in multivariate analyses (HR = 1.45; 95% CI, 1.07-1.96; P = 0.015). In conclusion, SIAH2 protein expression is especially observed in ER-negative tumors. Its prognostic value in breast cancer does not add to current prognostic markers. The proportion of SIAH2-positive cells can be used as biomarker to predict tamoxifen treatment failure in MBC patients.
