Basic Study
Copyright ©The Author(s) 2019. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Jul 7, 2019; 25(25): 3196-3206
Published online Jul 7, 2019. doi: 10.3748/wjg.v25.i25.3196
Sporamin suppresses growth of xenografted colorectal carcinoma in athymic BALB/c mice by inhibiting liver β-catenin and vascular endothelial growth factor expression
Chun Yang, Jing-Jie Zhang, Xiao-Peng Zhang, Rong Xiao, Peng-Gao Li
Chun Yang, Jing-Jie Zhang, Xiao-Peng Zhang, Rong Xiao, Peng-Gao Li, School of Public Health, Capital Medical University, Beijing Key Laboratory of Clinical Epidemiology, Beijing 100069, China
Author contributions: Yang C and Zhang JJ contributed equally to the work and should be regarded as co-first authors; Li PG designed the research; Zhang JJ and Zhang XP performed the research; Yang C and Zhang JJ analyzed the data and wrote the paper; Xiao R revised the manuscript; Li PG has primary responsibility for the final content.
Supported by the National Natural Science Foundation of China, No. 81573128 and No. 81703216.
Institutional animal care and use committee statement: This study was approved by the institutional animal care and use committee of Capital Medical University.
Conflict-of-interest statement: The authors declare no conflicts of interest.
ARRIVE guidelines statement: The authors have read the ARRIVE guidelines, and the manuscript was prepared and revised according to the ARRIVE guidelines.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Corresponding author: Peng-Gao Li, PhD, Associate Professor, School of Public Health, Capital Medical University, Beijing Key Laboratory of Clinical Epidemiology, 10 Xitoutiao, You An Men Wai, Fengtai District, Beijing 100069, China. penggao@ccmu.edu.cn
Telephone: +86-10-83911651 Fax: +86-10-83911651
Received: February 23, 2019
Peer-review started: February 23, 2019
First decision: April 4, 2019
Revised: May 14, 2019
Accepted: May 31, 2019
Article in press: June 1, 2019
Published online: July 7, 2019
Processing time: 133 Days and 23.2 Hours
ARTICLE HIGHLIGHTS
Research background

Colorectal cancer (CRC) is the third most common malignancy of the digestive tract and the fifth leading cause of cancer-related mortality in China. Sporamin, a Kunitz-type trypsin inhibitor isolated from sweet potato, is a potential anti-cancer agent with activity against a number of malignant tumor cells in vitro. The liver secretes a myriad of endocrine factors that may facilitate the growth and transformation of tumors in the development of CRC.

Research motivation

Sporamin as a potential anti-cancer agent against a number of malignant tumor cells, including HT29, HCT116, and SW480 colorectal cancer cells, TCA8113 tongue carcinoma cells as well as PANC-1 and BxPC-3 pancreatic cancer cells. However, the effects of sporamin on the expression and secretion of tumor biomarkers in the liver are currently unknown. Therefore, in the present study, LoVo colorectal carcinoma cells were intraperitoneally xenografted into athymic BALB/c nude mice and sporamin was given orally to the mice to observe its effect on the growth of tumors, with a focus on changes in the structure and function of the liver, especially the expression and secretion of β-catenin and vascular endothelial growth factor (VEGF).

Research objectives

To investigate the effects of sporamin on liver morphology and biomarkers of xenografted CRC in the liver of BALB/c athymic mice.

Research methods

Twenty-seven male BALB/c nude mice were randomly divided into control, vehicle, and sporamin groups. Mice in the latter two groups were intraperitoneally xenografted with LoVo colorectal carcinoma cells and intragastrically infused with saline or sporamin (0.5 g/kg body weight/d), respectively, for 3 weeks. Hematoxylin and eosin (HE) staining of the sections was performed to observe morphological changes in hepatic tissue and real-time fluorescent quantitative PCR and enzyme-linked immunosorbent assays (ELISA) were used to measure the expression of β-catenin and VEGF in the liver.

Research results

Sporamin significantly reduced the number and weight of tumor nodules formed in the abdominal cavity. Compared with the vehicle group, the mean tumor weight (± SD) in the sporamin group was significantly reduced (0.26 ± 0.15 g vs 0.44 ± 0.10 g) and the total number of tumors decreased from 93 to 55. HE staining showed that enlargement of the nucleus and synthesis of proteins within hepatocytes, as well as infiltration of inflammatory cells into the liver, were attenuated by sporamin. Immunohistochemical staining and ELISA showed that the concentrations of β-catenin and VEGF in the liver were significantly reduced by sporamin. Compared with the vehicle group, the expression of β-catenin measured in integrated optical density units per area was reduced in the sporamin group (47.29 ± 9.10 vs 26.14 ± 1.72; P = 0.003). Expression of VEGF was also reduced after sporamin intervention from 20.78 ± 2.06 in the vehicle group to 15.80 ± 1.09 in the sporamin group (P = 0.021). The secretion of VEGF and β-catenin in the liver was also assessed by ELISA, which showed that the concentration of VEGF in liver tissue increased significantly from 132.05 ± 7.96 pg/mL in the control group to 158.73 ± 6.23 pg/mL in the sporamin-treated group (P = 0.00007). Compared with the vehicle group, the concentration of β-catenin decreased from 134.42 ± 22.04 pg/mL to 109.07 ± 9.65 pg/mL after sporamin intervention (P = 0.00002). Quantitative PCR (qPCR) indicated that compared to the vehicle group, relative mRNA expression of β-catenin and VEGF in the liver of the sporamin-treated group was significantly reduced to 71% ± 1% (P = 0.000001) and 23% ± 7% (P = 0.00002), respectively, of the vehicle group levels.

Research conclusions

Sporamin down-regulates the expression and secretion of β-catenin and VEGF in the liver, which subsequently inhibits the transcription of downstream genes involved in cancer progression and angiogenesis.

Research perspectives

Our study suggests that sporamin can suppress the growth of xenografted colorectal tumor nodules in mice by restoring the normal structure of the liver and downregulating the expression and secretion of β-catenin and VEGF in the liver. These anti-cancer effects of sporamin against CRC are closely associated with its inhibitory effect on these tumor biomarkers. Further studies are warranted to elucidate the corresponding signal transduction events mediating this process.