Cucurbitacin B induces apoptosis in colorectal cells through reactive oxygen species generation and endoplasmic reticulum stress pathways

Abstract

Cucurbitacin B (CuB) is a member of the cucurbitacin family, which has shown potent anticancer pharmacological activity. Prolonged or severe endoplasmic reticulum stress (ERS) induces apoptosis; therefore, the present study investigated whether CuB may activate the ERS pathway to induce apoptosis. HT-29 and SW620 colorectal cancer (CRC) cells were treated with a range of concentrations of CuB for 48 h, and the viability and proliferation of cells were determined using Cell Counting Kit 8 (CCK8) and colony formation assays. Subsequently, the appropriate CuB concentration (5 µM) was selected for treatment of CRC cells for 48 h. Western blot analysis was used to measure the expression levels of ERS-related proteins, flow cytometry was used to evaluate apoptosis, the dichlorodihydrofluorescein diacetate fluorescent probe was used to detect reactive oxygen species (ROS) production, and the relationship between ROS and ERS was determined by western blot analysis. Furthermore, flow cytometry was used to evaluate apoptosis after treatment with the ERS inhibitor 4-phenylbutyric acid, the ROS inhibitor N-acetylcysteine and following knockdown of CHOP expression. In addition, western blot analysis was performed to measure Bax and Bcl2 protein expression levels, and a CCK8 assay was performed to evaluate the viability of cells following knockdown of CHOP. Notably, CuB treatment increased apoptosis and inhibited cell proliferation in CRC cell lines, and these effects were mediated by ROS and ROS-regulated activation of the PERK and XBP1 ERS pathways. In conclusion, CuB may induce apoptosis in HT-29 and SW620 CRC cells via ROS and ERS.

The dual effect of endoplasmic reticulum stress in digestive system tumors and intervention of Chinese botanical drug extracts: a review

“…Cucurbitacin, triterpenoid including cucurbitacin B and cucurbitacin E, are triterpenoids from the cucurbitaceae family Cucumis melo L., which have therapeutic effects on a wide range of tumors ( Hong T et al, 2023 ; Hsu HL et al, 2023 ; Yang Y et al, 2023 ). Huang JL et al (2023) found that cucurbitacin B (0.005, 0.01, 0.05, 1, 5, 10, 20, 40, 100 μM for 48 h) inhibited the proliferation and induced apoptosis of CRC cells HT-29 and SW620 by concentration-dependently increasing the protein expression of p-PERK, p-eIF2α, ATF4, IRE1α and XBP1. After CHOP knockdown, the apoptosis rate was significantly decreased.…”

“…Nobiletin, a flavonoid from the botanical drug Pericarpium Citri Reticulatae and its variants, has a variety of biological effects such as antithrombotic, anti-inflammatory and antioxidant ( Geng YZ et al, 2023 ; Huang L et al, 2023 ). Chen M et al (2023) found that nobiletin inhibited the proliferation of GC cells HGC-27 and MKN-28, which may be mediated through the activation of IRE-1α/GRP78/CHOP axis.…”

“…Oxymatrine from the root of the botanical drug Sophora flavescens Aiton has anti-inflammatory and antioxidant effects and is an alkaloid able to ameliorate a variety of diseases of the cardiovascular system and digestive system ( Huang X et al, 2023 ; Xu DR et al, 2023 ). Fang W et al (2019) observed that oxymatrine (30, 60, 90 μmol/L for 24, 48, 72 h) upregulated intracellular GRP78/Bip and Caspase-12 gene and protein expression levels, inhibited cancer cell growth, and induced Caspase-12-dependent ERS apoptosis and G2/M phase cell block in GC cells BGC-823 in a time- and concentration-dependent manner.…”

“…Furanocoumarin is one of the main coumarin components of the botanical drug Hansenia weberbaueriana (Fedde ex H. Wolff) Pimenov and Kljuykov, which has antiviral effect among others ( Zhao J, 2015 ). Cell experiments (12.5, 25, 50, 100 μmol/L for 24, 48, 72 h) and animal experiments (30 Μm/d for 4 weeks) in mice showed that furanocoumarins inhibit HepJ5 and Mahlavu cell viability and induce apoptosis in HCC cells in vitro and in vivo by upregulating PERK and CHOP ( Huang TY et al, 2023 ).…”