RESUMEN
BACKGROUND: The SWI/SNF complex is an important chromatin remodeler, commonly dysregulated in cancer, with an estimated mutation frequency of 20%. ARID1A is the most frequently mutated subunit gene. Almost nothing is known about the other familiar members of the SWI/SNF complexes, SMARCA2 (BRM), SMARCA4 (BRG1) and SMARCB1 (INI1), in oesophageal adenocarcinoma (EAC). METHODS: We analysed a large cohort of 685 patients with EAC. We used four different antibodies to detect a loss-of-protein of ARID1A BRM, BRG1 and INI1 by immunohistochemistry and correlated these findings with molecular and clinical data. RESULTS: Loss of ARID1A, BRG1, BRM and INI1 was observed in 10.4, 3.4, 9.9 and 2% of EAC. We found a co-existing protein loss of ARID1A and BRM in 9.9% and of ARID1A and BRG1 in 2.2%. Patients with loss of ARID1A and TP53 wildtype EACs showed a shortened overall survival compared with AIRDA1A-positive tumours [median overall survival was 60.1 months (95%CI 1.2-139.9 months)] in patients with ARIDA-1A expression and 26.2 months (95%CI 3.7-19.1 months) in cases of ARIDA-1A loss (p = 0.044). Tumours with loss or expression of ARID1A and TP53 loss were not associated with a difference in survival. Only one tumour revealed high microsatellite instability (MSI-H) with concomitant ARID1A loss. All other ARID1A loss-EACs were microsatellite-stable (MSS). No predictive relevance was seen for SWI/SNF-complex alterations and simultaneous amplification of different genes (PIK3CA, KRAS, c-MYC, MET, GATA6, ERBB2). CONCLUSION: Our work describes, for the first time, loss of one of the SWI/SNF ATPase subunit proteins in a large number of adenocarcinomas of the oesophagus. Several papers discuss possible therapeutic interventions for tumours showing a loss of function of the SWI/SNF complex, such as PARP inhibitors or PI3K and AKT inhibitors. Future studies will be needed to show whether SWI/SNF complex-deficient EACs may benefit from personalized therapy.
Asunto(s)
Adenocarcinoma/metabolismo , Adenosina Trifosfatasas/genética , ADN Helicasas/metabolismo , Proteínas de Unión al ADN/metabolismo , Neoplasias Esofágicas/metabolismo , Proteínas Nucleares/metabolismo , Proteína SMARCB1/metabolismo , Factores de Transcripción/metabolismo , Adenocarcinoma/genética , Adenocarcinoma/mortalidad , Adenocarcinoma/patología , Adenosina Trifosfatasas/metabolismo , Anciano , Biomarcadores de Tumor/análisis , Ensamble y Desensamble de Cromatina , Estudios de Cohortes , ADN Helicasas/genética , Proteínas de Unión al ADN/genética , Neoplasias Esofágicas/genética , Neoplasias Esofágicas/mortalidad , Neoplasias Esofágicas/patología , Femenino , Humanos , Inmunohistoquímica , Estimación de Kaplan-Meier , Mutación con Pérdida de Función , Masculino , Persona de Mediana Edad , Análisis Multivariante , Proteínas Nucleares/genética , Pronóstico , Proteína SMARCB1/genética , Factores de Transcripción/genética , Proteína p53 Supresora de Tumor/genética , Proteína p53 Supresora de Tumor/metabolismoRESUMEN
Publications describe the relevance of the AT-rich interactive domain-containing protein 1A (ARID1a) mutation in gastric adenocarcinoma, which occurs predominantly in the microsatellite instable (MSI)- and Epstein-Barr virus (EBV)-associated subtypes. It is unclear whether potential therapeutic, prognostic or morphologic descriptions are not epiphenomena of MSI (or EBV). Since personalised therapeutics are largely lacking for oesophageal adenocarcinoma (EAC), clinical trials investigating the efficacy of these therapeutics specifically in this subgroup are useful. To the best of our knowledge, this was the first study analysing the relevant tumour subset of microsatellite-stable (MSS) EAC with loss of function of ARID1a. A total of 875 patients with EAC and data from The Cancer Genome Atlas (TCGA) were analysed. Statistical analyses associating previously known molecular characteristics of the present tumour cohort, overall survival, morphological growth patterns and tumour heterogeneity issues were considered. Subsequently, 10% of EAC were ARID1a-deficient, the majority of which were MSS (7.5%). There was no characteristic growth pattern. Approximately 60% of tumours were PD-L1 positive to varying degrees. TP53 mutations occurred together with ARID1a defective EAC in the present cohort and in the TCGA collective. The extent of 7.5% MSS-EAC with ARID1a loss was unaffected by neoadjuvant therapy. ARID1a loss was often detected to be homogeneous (92%). ARID1a loss is not an epiphenomenon of MSI in EAC. The high homogeneity of ARID1a loss tumour clones could be considered an argument for the effectiveness of potential therapeutics. Since the majority of genomic ARID1a alterations result in protein loss, immunohistochemistry is a useful screening technique, especially in the absence of morphological characteristics.