Abstract
Sporamin, a proteinase inhibitor isolated from the sweet potato (Ipomoea batatas), has shown promising anticancer effect against colorectal cancer (CRC) in vitro and in vivo but its mechanisms of action are poorly understood. In the present study, high throughput RNA sequencing (RNA-seq) technology was applied to explore the transcriptomic changes induced by sporamin in the presence of thapsigargin (TG), a non-12-O-tetradecanolphorbol-13-acetate type cancer promoter, in the LoVo human CRC cells. Cellular total RNA was extracted from the cells after they were treated with vehicle (CTL), 1 μM of thapsigargin (TG), or 1 μM of TG plus 30 μM of sporamin (TGSP) for 24 h. The migratory capacity of the cells was determined by wound healing assay. The gene expression profiles of the cells were determined by RNA-seq on an Illumina platform. GO enrichment analysis, KEGG pathway analysis, protein-protein interaction (PPI) network construction, and transcription factors (TF) prediction were all performed based on the differentially expressed genes (DEGs) across groups with a series of bioinformatics tools. Finally, the effect and potential molecular targets of the sporamin at the transcriptome level were evaluated. Sporamin significantly inhibited the migration of cells induced by TG. Among the 17915 genes detected in RNA-seq, 46 DEGs were attributable to the effect of sporamin. RT-PCR experiment validated that the expression of RGPD2, SULT1A3, and BIVM-ERCC5 were up-regulated while NYP4R, FOXN1, PAK6, and CEACAM20 were down-regulated. Sporamin enhanced the mineral absorption pathway, worm longevity regulating pathway, and pyrimidine metabolism pathway. Two TFs (SMIM11A and ATOH8) were down-regulated by sporamin. HMOX1 (up-regulated) and NME1-NME2 (down-regulated) were the main nodes in a PPI network consisting of 16 DEGs that were modulated by sporamin in the presence of TG. Sporamin could favorably alter the gene expression profile of CRC cells, up-regulating the genes that contribute to the homeostasis of intracellular metal ions and the activities of essential enzymes and DNA damage repairment. More studies are warranted to verify its effect on specific genes and delineate the mechanism of action implicated in the process.
Highlights
Colorectal cancer (CRC) is the world’s fourth deadliest cancer that kills approximately 700,000 people annually
To investigate the anti-metastasis effect of sporamin in CRC, in the present study, the human LoVo CRC cells were stimulated with thapsigargin (TG), a non-12-O-tetradecanolphorbol-13acetate (TPA) type [13] cell migration promoter [14]
Dulbecco’s Modified Eagle Medium (DMEM)-high glucose, fetal bovine serum (FBS), and phosphate balanced solution were from Corning (New York, USA)
Summary
Colorectal cancer (CRC) is the world’s fourth deadliest cancer that kills approximately 700,000 people annually. Sporamin is a serine proteinase inhibitor found in the dicotyledonous plant sweet potato (Ipomoea batatas) [6], and has a potent antioxidant [7], anti-obesity [8], and anticancer effect. It can suppress proliferation and induce apoptosis of many malignant cells such as HT29, HCT116, and SW480 CRC cells [9], the EC9706 and EC109 human esophageal squamous cancer cells [10], the Tca8113 human tongue carcinoma cells [11], and the PANC-1 human pancreatic cancer cells [12]. The results were analyzed with a series of bioinformatics tools to elucidate the potential molecular targets of sporamin in the cells
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