Esophageal squamous cell carcinoma transcriptome reveals the effect of FOXM1 on patient outcome through novel PIK3R3 mediated activation of PI3K signaling pathway

// Pedro Nicolau-Neto 1 , Nathalia Meireles Da Costa 1 , Paulo Thiago de Souza Santos 1 , Isabela Martins Gonzaga 1 , Maria Aparecida Ferreira 2 , Simone Guaraldi 2 , Miguel Angelo Moreira 3 , Hector N. Seuanez 3 , Lilian Brewer 4 , Anke Bergmann 1 , Mariana Boroni 3 , Andre Luiz Mencalha 5 , Cleber Dario Pinto Kruel 6 , Sheila Coelho Soares Lima 1 , Dominic Esposito 7 , Tatiana Almeida Simao 4 and Luis Felipe Ribeiro Pinto 1, 4 1 Molecular Carcinogenesis Program, Instituto Nacional de Câncer (INCA), Rio de Janeiro, 20231-050 RJ, Brasil 2 Endoscopy Section, Instituto Nacional de Câncer (INCA), Praca Cruz Vermelha, 20230-130 RJ, Brasil 3 Genetic Program, Instituto Nacional de Câncer (INCA), Rio de Janeiro, 20231-050 RJ, Brasil 4 Biochemistry Department, Instituto de Biologia Roberto Alcântara Gomes, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, 20551-030 RJ, Brasil 5 Biophysics and Biometry Department, Instituto de Biologia Roberto Alcântara Gomes, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, 20551-030 RJ, Brasil 6 Surgery Department, Faculty of Medical Sciences, Universidade Federal do Rio Grande do Sul, Porto Alegre, 90035-003 RS, Brasil 7 Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, 21701 MD, USA Correspondence to: Luis Felipe Ribeiro Pinto, email: lfrpinto@inca.gov.br Keywords: esophageal squamous cell carcinoma; FOXM1; PIK3R3; PI3K/AKT pathway; target therapy Received: August 15, 2017     Accepted: February 22, 2018     Published: March 30, 2018 ABSTRACT Esophageal squamous cell carcinoma (ESCC) presents poor prognosis, and patients diagnosed with this tumor currently lack target treatments. Therefore, in order to identify potential targets for ESCC treatment, we carried out a transcriptome analysis with ESCC and paired nonmalignant surrounding mucosa samples, followed by a master regulator analysis, and further explored the role of the identified central regulatory genes through in vivo and in vitro assays. Among the transcription factors deregulated/enriched in ESCC, we focused on FOXM1 because of its involvement in the regulation of critical biological processes. A new transcriptome analysis performed with ESCC cell lineage TE-1 showed that the modulation of FOXM1 expression resulted in PIK3R3 expression changes, whereas chromatin immunoprecipitation assay revealed that FOXM1 was capable of binding onto PIK3R3 promoter, thus demonstrating that PIK3R3 is a new FOXM1 target. Furthermore, FOXM1 overexpression resulted in the activation of PIK3/AKT signaling pathway through PIK3R3-mediated AKT phosphorylation. Finally, the analysis of the clinic-pathological data of ESCC patients revealed that overexpression of both FOXM1 and PIK3R3 was associated with poor prognosis, but only the latter was an independent prognosis factor for ESCC patients. In conclusion, our results show that FOXM1 seems to play a central role in ESCC carcinogenesis by upregulating many oncogenes found overexpressed in this tumor. Furthermore, PIK3R3 is a novel FOXM1 target that triggers the activation of the PI3K/AKT pathway in ESCC cells.