Shallot and licorice constituent isoliquiritigenin arrests cell cycle progression and induces apoptosis through the induction of ATM/p53 and initiation of the mitochondrial system in human cervical carcinoma HeLa cells

Abstract

This study is the first to investigate the anticancer effect of isoliquiritigenin (ISL) in human cervical carcinoma HeLa cells. The results reveal that ISL inhibits HeLa cells by blocking cell cycle progression in the G2/M phase and inducing apoptosis. Blockade of cell cycle is associated with increased activation of ataxia telangiectasia-mutated (ATM). Activation of ATM by ISL phosphorylated p53 at Serine15, resulting in increased stability of p53 by decreasing p53 and murine double minute-2 (MDM2) interaction. In addition, ISL-mediated G2/M phase arrest was also associated with decreases in the amounts of cyclin B, cyclin A, cdc2, and cdc25C, and increases in the phosphorylation of Chk2, cdc25C, and cdc2. The specific ATM inhibitor caffeine significantly decreased ISL-mediated G2/M arrest by inhibiting the phosphorylation of p53 (Serine15) and Chk2. ISL induced apoptotic cell death is associated with changes in the expression of Bax and Bak, decreasing levels of Bcl-2 and Bcl-X(L), and subsequently triggering mitochondrial apoptotic pathway. In addition, pretreatment of cells with caspase-9 inhibitor blocked ISL-induced apoptosis, indicating that caspase-9 activation is involved in ISL-mediated HeLa cell apoptosis. These findings suggest that ISL may be a promising chemopreventive agent against human uterine cervical cancer.

Chemopreventive Effects of Licorice and Its Components

“…Notably, oral administration of ILQ attenuated the induction of preneoplastic aberrant crypt foci in the colon of male F344 rats [59]. This licorice compound abrogated G2/M cell cycle progression and effectively induced apoptosis in HeLa human uterine cervical cancer cells [62]. Investigators observed activation of ataxia telangiectasia-mutated (ATM), increased phosphorylation of p53 (Ser15) and changes in several cell cycle proteins, including cyclin B, cyclin A, cell division cycle protein (Cdc)2, cdc25C, and checkpoint kinase (Chk)2.…”

“…Investigators observed activation of ataxia telangiectasia-mutated (ATM), increased phosphorylation of p53 (Ser15) and changes in several cell cycle proteins, including cyclin B, cyclin A, cell division cycle protein (Cdc)2, cdc25C, and checkpoint kinase (Chk)2. Apoptosis corresponded with changes in pro-apoptotic Bax and Bak and decreased levels of antiapoptotic Bcl-2 and Bcl-XL in HeLa cells [62]. Interestingly, ILQ could inhibit in vivo lung metastasis of MDA-MB-231 breast cancer cells by preventing resistance to anoikis [63•], which is a type of apoptosis induced by anchorage-dependent cells detaching from the extracellular matrix around them [64].…”

Characteristic Features of Cytotoxic Activity of Flavonoids on Human Cervical Cancer Cells

“…Radical surgery or radiotherapy can be curative for the majority of patients with early-stage cervical cancer; however, chemotherapy is always the first choice for patients with the advanced disease for which the prognosis remains very poor (Zhang B et al, 2006;Li et al, 2009;Kim et al, 2010;Al-Hazzani and Alshatwi, 2011;Ju et al, 2012;Alshatwi et al, 2013;Ramesh and Alshatwi, 2013;Zhu et al, 2013;Jin et al, 2014). Although the platinumor taxane-based chemotherapy either neoadjuvant before surgery or combined with radiotherapy can significantly improve the survival of patients, the success of these treatment modalities is often hindered by emerging of chemoresistance and/or radioresistance as well as by severe lethality on normal cells resulting in serious toxicity (Hsu et al, 2009;Koppikas et al, 2010;Singh et al, 2010;Liu et al, 2012;Chen et al, 2013b;Chen et al, 2013a;Lo et al, 2013;Singh et al, 2013;Zhu et al, 2013). Therefore, the survival benefit of conventional therapies is limited, relapse can occur after treatment, and cervical cancer continues to have one of the lowest five-year survival rates being only about 52% (Hsu et al, 2009;Singh et al, 2010;Chen et al, 2011;Zeng et al, 2012a;Kim and Kim, 2013;Singh et al, 2013).…”

“…Although the platinumor taxane-based chemotherapy either neoadjuvant before surgery or combined with radiotherapy can significantly improve the survival of patients, the success of these treatment modalities is often hindered by emerging of chemoresistance and/or radioresistance as well as by severe lethality on normal cells resulting in serious toxicity (Hsu et al, 2009;Koppikas et al, 2010;Singh et al, 2010;Liu et al, 2012;Chen et al, 2013b;Chen et al, 2013a;Lo et al, 2013;Singh et al, 2013;Zhu et al, 2013). Therefore, the survival benefit of conventional therapies is limited, relapse can occur after treatment, and cervical cancer continues to have one of the lowest five-year survival rates being only about 52% (Hsu et al, 2009;Singh et al, 2010;Chen et al, 2011;Zeng et al, 2012a;Kim and Kim, 2013;Singh et al, 2013). Consequently, the development of more effective, highly selective and less toxic anticancer agents as well as novel therapeutic intervention strategies are needed to improve the treatment success and reduce the cervical cancer morbidity and mortality rate.…”

“…The common dietary licorice chalcone isoliquiritigenin has shown to reduce the cell viability by inducing cell cycle arrest and morphological and biochemical features of apoptosis in both HPV16-(CaSki, SiHa) and HPV18-positive (HeLa) cell lines as well as HPV-negative cervical cancer cells (C33A) (Li et al, 2008;Hsu et al, 2009;Park et al, 2009;Hirchaud et al, 2013). Increase in intracellular reactive oxygen species (ROS) and triggering oxidative stress may play a critical role in isoliquiritigenin induced HeLa cell apoptosis (Yuan X et al, 2012;Yuan et al, 2013).…”