Exosomal SPINT1-AS1 Promotes the Development of Colorectal Cancer and Serves as a Non-Invasive Biomarker

Abstract

Background: The contribution of natural antisense transcripts (NATs) to tumorigenesis is an area of intensive investigation. Previously, we demonstrated highly expressed SPINT1-AS1 in colorectal cancer (CRC) was linked to poor clinical outcome. In this study, we investigated the regulatory role of SPINT1-AS1 on CRC cell phenotypes and determined the expression pattern of exosomal SPINT1-AS1. Methods: Loss- and gain-of-function assays were used to evaluate the regulation ability of SPINT1-AS1 on CRC cell phenotypes. Strand-specific RT-qPCR was used to detected exosomal SPINT1-AS1 expression in a cohort of serum samples including 100 normal colonoscopy (NC), 93 hyperplastic polyp (HP), 104 inflammatory bowel disease (IBD), 113 adenoma (Ad) and 240 CRC. Findings: SPINT1-AS1 overexpression significantly promoted CRC cell proliferation and autophagy while inhibited apoptosis in vitro. SPINT1-AS1 overexpression also drove tumorigenesis in vivo. Consistently, SPINT1-AS1 knockdown abolished CRC tumorigenesis manifested as inhibited cell proliferation and autophagy, as well as promoted apoptosis. Interestingly, SPINT1 mRNA overexpression led to the same phenotypes as SPINT1-AS1 knockdown in CRC cells. In addition, exosome-mediated SPINT1-AS1 transfer promoted CRC cells malignant behaviors. High expression of exosomal SPINT1-AS1 was observed in CRC which could distinguish between CRC from NC and benign colorectal diseases. Patients with high expression of exosomal SPINT1-AS1 had adverse clinical manifestation and shorter Disease-free survival (DFS). Interpretation: SPINT1-AS1 plays a carcinogenic role in CRC via regulating SPINT1 mRNA expression. SPINT1-AS1 can be secreted into exosomes, which suggests that SPINT1-AS1 has potential to act as a non-invasive diagnostic and prognostic biomarker for CRC. Funding: This work was supported by grant from the Natural Science Foundation of China (81472025, 81772271, 81301506 and 81601846), Shandong Technological Development Project (2018YFJH0505), Shandong Medical and Health Technology Development Project (2018WSB20002), Jinan Science and Technology Development Plan (201805003), Natural Science Foundation of Shandong Province (ZR2015CM030) and Taishan Scholar Program of Shandong Province. Declaration of Interest: The authors declare no conflict of interest. Ethical Approval: This study was approved by the Ethics Committee of Qilu Hospital of Shandong University, and written informed consent was signed by each patients.