Reduction of SCUBE3 by a new marine-derived asterosaponin leads to arrest of glioma cells in G1/S

Peng-Cheng Qiu,Shan Zhang,Yun-Yang Lu,Hua Li,Yu-Qiang Ji,Hai-Feng Tang,Han Bao,Guang Cheng,Fei Fang

doi:10.1038/s41389-020-00252-4

Peng-Cheng Qiu, Shan Zhang + Show 7 more

Open Access

https://doi.org/10.1038/s41389-020-00252-4

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Abstract

Many saponins are characterized as exhibiting a wide spectrum of antitumor activities at low concentrations. Most of the previous studies that aimed to understand the mechanisms underlying anticancer saponins have focused on numerous classical signaling pathways. However, at the oncogene level, little is known about the action of saponins, especially asterosaponin. In this study, CN-3, a new asterosaponin isolated from the starfish Culcita novaeguineae, decreased the proliferation of U87 and U251 cells at low doses in a dose- and time-dependent manner. Microarray analysis revealed CN-3 significantly induced the differential expression of 661 genes that are related to its antiglioma effect in U251. Nine downregulated genes (SCUBE3, PSD4, PGM2L1, ACSL3, PRICKLE1, ABI3BP, STON1, EDIL3, and KCTD12) were selected, for further verification of their low expression. Then, shRNA transfection and high-content screening were performed and significantly decreased U251 cell proliferation rate was only observed for the SCUBE3 knockdown. qPCR confirmed SCUBE3 was highly expressed in U251 and U87 cells, and had medium expression levels in U373 cells. Real-time cellular analysis using iCELLigence demonstrated that SCUBE3 is an oncogene in U251 and U87 cells, with knockdown of SCUBE3 inhibiting U251 and U87 cell proliferation while, conversely, SCUBE3 overexpression promoted their proliferation. Afterward, SCUBE3 protein was found to have high expression in primary glioma specimens from patients examined by immunohistochemistry but low expression in normal brain. PathScan ELISA analysis in conjunction with TEM observation demonstrated that the effect of SCUBE3 knockdown in U251 does not appear to be related to the induction of apoptosis. Employing CCK-8, iCELLigence, flow cytometry, western blotting, and shRNA transfection (knockdown and overexpression) experiments, we reveal that the reduction of SCUBE3 expression, induced by CN-3, mediated both inhibition and G1/S arrest of U251 via the Akt/p-Akt/p53/p21/p27/E2F1 pathway.

Highlights

IntroductionGliomas are the most common primary intracranial tumor, representing ~24.7% of all primary brain and other
Gliomas are the most common primary intracranial tumor, representing ~24.7% of all primary brain and otherCNS tumors[1]
IC40 was used as a low dose and IC70 was used as a high dose of CN-3 for treating U251 and U87 cells

Summary

Introduction

Gliomas are the most common primary intracranial tumor, representing ~24.7% of all primary brain and other. Glioblastoma is the most common and malignant type of glioma (~45% of all gliomas), and it is associated with a median overall survival of 15 months after resection and combined radiochemotherapy[2], and the 5-year relative survival rate is ~5%3,4. There is an urgent need to find new antiglioma drugs. Natural product-derived compounds have displayed potent antitumor activities. Saponins, characterized by a wide spectrum of antitumor activities, are derived from some higher plants and animal sources[5,6]. Including our previous work in some cases, anticancer saponins have been isolated from Anemone tomentosa[7], Clematis

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