Plumbagin Exhibits Genotoxicity and Induces G2/M Cell Cycle Arrest via ROS-Mediated Oxidative Stress and Activation of ATM-p53 Signaling Pathway in Hepatocellular Cells

Abstract

Plumbagin (5-hydroxy-2-methyl-1,4-naphthoquinone, PLB), a naturally occurring naphthoquinone mainly isolated from the plant Plumbago zeylanica L., has been proven to possess anticancer activities towards multiple types of cancer. Although there has been an increasing amount of research regarding its anticancer effects, the association between oxidative stress, genotoxicity and the cell cycle arrest induced by PLB still remains unclear. Therefore, it is important to investigate their potential connections and the involvement of DNA damage and the ataxia telangiectasia mutated protein (ATM)-p53 signaling pathway in PLB’s anticancer mechanism. The present study showed that PLB exposure significantly reduced HCC cell viability and colony formation. In addition, PLB-induced G2/M cell cycle arrest, oxidative stress, and DNA damage was detected, which could be almost blocked by NAC pretreatment. PLB could trigger a DNA damage response by activating cell cycle checkpoints such as ATM, checkpoint kinase 1 (Chk1), checkpoint kinase 2 (Chk2) and p53. Meanwhile, the key modulator of the G2/M transition factor, Cell Division Cycle 25C (cdc25C), was significantly downregulated in an ROS-dependent manner. Furthermore, pretreatment with ATM and p53 inhibitors (KU55933 and Pifithrin-α) could reduce the occurrence of G2/M cell cycle arrest by inhibiting the activation of the ATM-p53 pathway. Taken together, these results indicate that ROS-mediated oxidative stress plays a key role in PLB-induced G2/M cell cycle arrest mediated by the ATM-p53 pathway.

Quercetin suppresses ROS production and migration by specifically targeting Rac1 activation in gliomas

“…Although the human body has an innate antioxidant defense mechanism to counter oxidative species in cells, it may not function once ROS exceeds a threshold level leading to cellular stress. The overproduction of ROS, particularly peroxides, tends to alter cell cycle phases, eventually leading to cancer ( Mehraj et al, 2022a ; Mehraj et al, 2022b ; Chen J-S. et al, 2023 ; Liu et al, 2023 ). The situation becomes more vulnerable in metabolically active tissues such as the brain which, apart from being less equipped with innate antioxidant defense, also tend to resist the delivery of drugs due to the blood–brain barrier ( Rinaldi et al, 2016 ).…”

Use of antioxidant nanoliposomes for co-delivery of PTEN plasmids and plumbagin to induce apoptosis in hepatic cancer cells

“…In order to unravel the fundamental mechanisms contributing to the inhibition of cell proliferation, cell cycle progression of exposed HepG2 cells was studied using flow cytometer. Plumbagin is well-known to arrest the cells in G2/M phase and inhibit cancer cell proliferation [24]. Lipo-Plum (2.5 µg ml −1 , figure 7(C)) and Lipo-PTEN-Plum (PTEN-0.05 µg ml −1 & Plum-2.5 µg ml −1 , figure 7(E)) exposure to HepG2 cells resulted in 39.49%-42.56% cell population in G2/M phase compared to control (∼33%, figure 7(A)).…”

An integrated in vitro carcinogenicity test that distinguishes between genotoxic carcinogens, non-genotoxic carcinogens, and non-carcinogens

“…The relatively high number of endpoints altered by GCs supported the use of the chosen endpoints for identifying chemicals with genotoxic cellular effects. It is well established that alterations in p53, p21, and cell cycle dynamics (which influence cell and nuclear area) occur in response to genotoxic stress [ 21 , 22 ], and even non-genotoxic stress [ 23 ].…”