Aminopeptidase A initiates tumorigenesis and enhances tumor cell stemness via TWIST1 upregulation in colorectal cancer

// Hui-Yu Chuang 1 , Jeng-Kae Jiang 3, 4 , Muh-Hwa Yang 5, 6, 8, 10, 11 , Hsei-Wei Wang 2, 8, 9 , Ming-Chun Li 12 , Chan-Yen Tsai 2 , Yau-Yun Jhang 1 , Jason C. Huang 1, 13 1 Department of Biotechnology and Laboratory Science in Medicine, National Yang-Ming University, Taipei, Taiwan 2 Institution of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan 3 Department of Surgery, School of Medicine, National Yang-Ming University, Taipei, Taiwan 4 Division of Colorectal Surgery, Department of Surgery, Taipei Veterans General Hospital, Taipei, Taiwan 5 Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan 6 Division of Hematology-Oncology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan 7 Institution of Biochemistry and Molecular Biology, National Yang-Ming University, Taipei, Taiwan 8 Cancer Research Center, National Yang-Ming University, Taipei, Taiwan 9 Department of Education and Research, Taipei City Hospital, Taipei, Taiwan 10 Immunity and Inflammation Research Center, National Yang-Ming University, Taipei, Taiwan 11 Genomic Research Center, Academia Sinica, Taipei, Taiwan 12 Division of Pediatrics, Taipei City Hospital, Yang-Ming Branch, Taipei, Taiwan 13 AIDS Prevention and Research Center, National Yang-Ming University, Taipei, Taiwan Correspondence to: Jason C. Huang, email: jchuang2@ym.edu.tw Keywords: colorectal cancer, aminopeptidase A, metastasis, TWIST1, cancer stem cell Received: October 26, 2016      Accepted: January 11, 2017      Published: February 03, 2017 ABSTRACT Metastasis accounts for the high mortality rate associated with colorectal cancer (CRC), but metastasis regulators are not fully understood. To identify a novel gene involved in tumor metastasis, we used oligonucleotide microarrays, transcriptome distance analyses, and machine learning algorithms to determine links between primary and metastatic colorectal cancers. Aminopeptidase A (APA; also known as ENPEP ) was selected as our focus because its relationship with colorectal cancer requires clarification. Higher APA mRNA levels were observed in patients in advanced stages of cancer, suggesting a correlation between ENPEP and degree of malignancy. Our data also indicate that APA overexpression in CRC cells induced cell migration, invasion, anchorage-independent capability, and mesenchyme-like characteristics (e.g., EMT markers). We also observed TWIST induction in APA-overexpressing SW480 cells and TWIST down-regulation in HT29 cells knocked down with APA. Both APA silencing and impaired APA activity were found to reduce migratory capacity, cancer anchorage, stemness properties, and drug resistance in vitro and in vivo . We therefore suggest that APA enzymatic activity affects tumor initiation and cancer malignancy in a TWIST-dependent manner. Results from RT-qPCR and the immunohistochemical staining of specimens taken from CRC patients indicate a significant correlation between APA and TWIST. According to data from SurvExpress analyses of TWIST1 and APA mRNA expression profiles, high APA and TWIST expression are positively correlated with poor CRC prognosis. APA may act as a prognostic factor and/or therapeutic target for CRC metastasis and recurrence.