Abstract 579: TAK1-regulated expression of BIRC3 is responsible for chemoradiotherapy (CRT) resistance in esophagogastric junction (EGJ) adenocarcinoma

Abstract

Abstract Introduction: Preoperative CRT followed by surgery is the most common approach for patients with resectable esophageal and EGJ cancers. Based on the histology, patients with adenocarcinoma consistently demonstrated significantly lower rate of pathological complete response if compared with patients with squamous cell carcinoma, thus the need for accurate biomarkers to select the patients with esophageal and EGJ adenocarcinoma most likely to benefit from preoperative CRT has become even more critical. We recently demonstrated that the MAP3K TGF-βeta-activated kinase-1 (TAK1) is responsible for the resistance to the proapoptotic effect of chemotherapeutic agents by increasing the transcription of the member of the inhibitor of apoptosis proteins family BIRC3 in preclinical models of pancreatic cancer. Here, we hypothesized that the TAK1-regulated expression of BIRC3 might be responsible for the resistance to CRT in EGJ adenocarcinoma. Materials and methods: TAK1 kinase activity was targeted in FLO-1 and KYAE-1 esophageal cells by using (5Z)-7oxozeaenol. To test the effect of reducing BIRC3 expression on the resistance to CRT, FLO-1 and KYAE-1 cells were treated with increasing doses of cisplatin, 5-fluorouracil, paclitaxel, or radiotherapy in combination with (5Z)-7oxozeaenol. Drug interactions were studied for synergism according to Chou and Talalay method. Apoptotic induction was studied by western blot analysis of PARP and caspase 3 cleavages as well as by AnnexinV staining. BIRC3 expression was measured in 33 pretreatment biopsies from patients with EGJ adenocarcinoma and 34 from patients with esophageal squamous cell carcinoma receiving neoadjuvant CRT by Real-Time PCR. Tumor response was evaluated by Tumour regression grade (TRG) and by Size-based Pathological Response (SPR) scores. Correlation between BIRC3 expression and treatment response was analysed by ROC curve analysis. Results: In vitro, (5Z)-7oxozeaenol significantly reduced BIRC3 expression in FLO-1 and KYAE-1 esophageal cells. Exposure to sublethal equitoxic doses of chemotherapeutic agents plus (5Z)-7oxozeaenol pretreatment resulted in a strong synergistic anti-proliferative effect. Baseline expression of BIRC3 was significantly higher in patients with EGJ adenocarcinoma if compared with the more sensitive squamous-cell carcinoma subtype. Moreover, patients with EGJ adenocarcinoma expressing higher pretreatment levels of BIRC3 had a significantly poorer treatment response than did those with lower expression, indicating that BIRC3 expression significantly correlates with response to preoperative CRT (AUC-ROC = 0.777 and 0.807 for SPR and TRG, respectively). Conclusions: TAK1-regulated expression of BIRC3 might be a valid biomarker to predict resistance to CRT in EGJ adenocarcinoma patients. Citation Format: Geny Piro, Simone Giacopuzzi, Maria Bencivenga, Carmine Carbone, Giuseppe Verlato, Melissa Frizziero, Maria Mihaela Mina, Marco Zanotto, Valeria Merz, Giovanni De Manzoni, Giampaolo Tortora, Davide Melisi. TAK1-regulated expression of BIRC3 is responsible for chemoradiotherapy (CRT) resistance in esophagogastric junction (EGJ) adenocarcinoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 579. doi:10.1158/1538-7445.AM2015-579