br Introduction br Colorectal cancer
Colorectal cancer (CRC) represents one of the most common ma-lignant tumors of digestive system worldwide, posing serious threats to human health (Schwingshackl et al., 2018). In China, CRC is the third most common cancer and the fifth most common causes of cancer death (Chen et al., 2016). More than that, the incidence and mortality of CRC are increasing day by day and there are still approximately one million new CRC cases and over 500,000 mortalities occur annually (Casagrande et al., 2013). Thus, there is an urgent need to identify novel anticancer agents that are nontoxic and highly eﬀective in in-ducing inhibition proliferation preferentially in colorectal cancer cells.
Natural products have been well recognized as sources of drugs in cancer treatment (Jeong et al., 2011). Some medicinal plants contain the constituents with potent anti-angiogenic and anti-cancer eﬀects, which have oﬀered great hopes of being used as drugs for treating various cancers. Cell cycle arrest, induction of apoptosis and inhibition of angiogenic factors in cancer cells are important eﬀects which are
associated with these plant-based drugs (Cragg and Newman, 2013; Gamet-Payrastre et al., 2000; Li et al., 2014; Torres and Horwitz, 1998). The roots of Toddalia asiatica, an important traditional Chinese medi-cine, have long history to be used for the treatment of cold, rheumatoid arthritis, blood stasis, as well as for its general analgesic properties (Santhi and Jegadeesan, 2000; Zhang, 1982). Currently, our studies indicated that the compound 8-Acetonyldihydronitidine (8-AHN), ex-tracted from Toddalia asiatica, has anti-proliferative eﬀect in colorectal cancer cell lines. What's more, our studies showed that it was involved in induction of G2/M MIK665 (S-64315) arrest and apoptosis in colorectal cancer cells for anticancer activity.
The TP53 gene encodes the tumor suppressor protein p53, known as ‘the guardian of the genome’, which ensures the fidelity of DNA re-plication and controls cell division, thereby preventing the formation and abnormal growth of cancerous cells (Moonen et al., 2018). p53 becomes stimulated upon genotoxic and other cellular stress signals including DNA damage, loss of cell adhesion, spindle damage, oncogene activation, nutrient deprivation, ribonucleoti depletion, and hypoxia
∗ Corresponding author. Department of Microbial and Biochemical Pharmacy, School of Pharmaceutical Sciences, Sun Yat-sen University, No. 132 Waihuan East Road, University Town, Guangzhou, 510006, China.
E-mail address: [email protected] (J. Du).
(Mello and Attardi, 2018). Ultimately, such stresses lead to p53-medi-ated transcriptional activation of genes involved in DNA repair, cell cycle arrest, cellular senescence, and apoptosis (Aubrey et al., 2018; Engeland, 2018). Among established p53 targets that participate in cell cycle and apoptosis are p21, BAX, FAS and so on (Sullivan et al., 2018). We found that the p53 played a central role in 8-AHN-induced cell proliferation inhibition.
This study revealed that 8-AHN induced cell cycle arrest and apoptosis though activation of p53 and transduced by p21, BAX, FAS and then activated caspase-3 and inhibited cyclin B and cyclin A. Furthermore, in vivo studies showed that 8-AHN significantly sup-pressed the growth of HCT116 colorectal cancer xenograft tumors, as-sociated with proliferation suppression and apoptosis induction in tumor tissues, without inducing any notable major organ-related toxi-city. Our results in vitro and in vivo suggested that 8-AHN could be used for the eﬀectively prevention and treatment of human colorectal cancer.
2. Materials and methods
8-AHN and other compounds (Fig. 1A) were extracted from the root of Toddalia asiatica and kindly donated by Professor Sheng Yin (Sun Yat-sen University, Guangzhou, China) (Li et al., 2017), dissolved in dimethyl sulfoxide (DMSO) to prepare a 40 mM stock solution, and