# Antitumor Effects of _Cannabis sativa_ Bioactive Compounds on Colorectal Carcinogenesis
## 3 Bioactive Compounds in the Prevention and Treatment of Colorectal Cancer
### Effects of Cannabinoids in CRC-Associated Mechanisms
#### 3.1.1 Cbd  
Isolated CBD is the most extensively studied cannabinoid in cancer research due to its numerous health benefits and non-psychoactive nature. This cannabinoid was described as cytotoxic in different types of CRC cells, inhibiting their viability, namely in HCT116, SW480, SW620, CACO-2, HT-29, and DLD-1 [46; 50; 51; 52]. [PERSON] et al. found that CBD suppressed cell viability through a mechanism dependent on the CB2 receptor and not on CB1. Additionally, normal human colon cells resisted CBD, establishing its safety for noncancer cells [50]. Furthermore, several CRC cell lines (CACO-2, HT-29, DLD-1, SW620, SW480, COLO205, and HCT116) suffered significant reductions in proliferation after treatment with CBD at different concentrations (2.5-15 uM) [47; 50; 52; 53; 54; 55]. In this way, its beneficial effects have become a target of study in different anticancer mechanisms. Resistance to apoptosis (cell death) is a hallmark of all types of cancer, so several apoptosis-inducing drugs have been developed as cancer therapies, including for CRC [56]. [PERSON] et al. [54] corroborated that CACO-2 CRC cells, treated with CBD (10 uM for 24 h), significantly decreased the expression of phospho-protein kinase B (Akt) (\(p<\) 0.001) and upregulated caspase-3 expression in colonic tissues of azoxymethane (AOM)-induced mice (CBD, 1 mg/kg). These data suggest that CBD can induce apoptosis involving the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway, essential in the regulation of cell growth, migration, differentiation, and apoptosis. In other CRC cell lines, namely, HCT-116, SW480, and SW620, this mechanism occurred through the antagonism of several receptors, including CB1, TRPV1, and PPAR\(\gamma\)[50]. This study conducted by [PERSON] and coworkers revealed that CBD arrested the cell cycle by lowering levels of cyclin-dependent kinases (CDKs) and cyclins, specifically cyclin D1 and D3, CDK2, CDK4, and CDK6, showing antiproliferative and pro-apoptotic properties. Additionally, CBD increased  
Figure 4: Schematic representation of endocannabinoid system components. GPR55, G-protein-coupled receptor 55; PPARs, peroxisome proliferatorator-activated receptor; TRPM8, transient receptor potential cation channel subfamily M member 8; TRPV1, transient receptor potential cation channel subfamily V member 1. The figure was partly generated using Servier Medical Art, provided by Servier, licensed under a Creative Commons Attribution 3.0 unported license. caspase-3/7 activity in a dose-dependent manner (5 and 10 \(\upmu\)M). In the same study, authors also revealed that induced apoptosis was also mediated by the increased expression of endoplasmic reticulum (ER) stress proteins, including binding immunoglobulin protein, inositol-requiring enzyme 1\(\upalpha\), phosphorylated eukaryotic initiation factor 2\(\upalpha\), activating transcription factor 3 (ATF3), and ATF4. A similar trend was found in a study realized by [PERSON] et al. in HCT116 and DLD-1 cells [46]. In fact, they demonstrated that increased reactive oxygen species (ROS) production contributed to an increment in Noxa levels via ER stress. Thus, the authors concluded that the induced apoptosis was mediated by Noxa activation, which led to caspase activation and poly (ADP-ribose) polymerase (PARP) cleavage. Consistent with that, Noxa levels were also elevated in the tumor tissues of female BALB/c nude mice (xenograft: HCT116), validating the Noxa-mediated apoptosis in an in vivo model. Moreover, [PERSON] et al. [51] reported that CBD increased apoptosis induced by tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL), increasing the expression of death receptor 5 through ER stress in HCT116, HT29, and DLD-1 cells. In vivo results also confirmed the rise in DR5 and C/EBP homologous protein (CHOP) expression, an ER stress-related protein, in tumor tissues. Additionally, it was shown that the combination of CBD and TRAIL significantly reduced the cells' ability to form colonies compared to controls (\(p<0.001\)). [PERSON] et al.