Keywords

1 Introduction

Cannabinoids are terpenophenolic compounds which are classified as plant-derived phytocannabinoids, endocannabinoids produced by humans and animals and synthetic forms produced in laboratory. These compounds have been extensively studied for their biological roles in physiological and pathological processes (Shah et al. 2021) including cell proliferation (Braile et al. 2021; Daris et al. 2019), migration (Daris et al. 2019; Kovalchuk and Kovalchuk 2020), invasion (Sledzinski et al. 2021; Tomko et al. 2020), angiogenesis (Lee et al. 2021; Wang and Multhoff 2021), autophagy (Hinz and Ramer 2019; Lee et al. 2021), and apoptosis (Leo and Abood 2021; Vecera et al. 2020). In recent years, many clinical studies concerning the cannabinoid management have been conducted on their relieving effect on chemotherapy-related nausea and vomiting, spasms, neuropathic pain, insomnia, and seizures (Mücke et al. 2018; Pauli et al. 2020; Sawtelle and Holle 2021). Therefore, this chapter focuses on the recent preclinical and clinical advances in the fields of cannabinoids and their effects on cellular mechanisms in healthy and cancerous cells.

2 Focus on Cannabinoids

2.1 Phytocannabinoids

Cannabis sativa L. (marijuana) plant comprises more than 100 psychoactive terpenophenolic compounds known as cannabinoids (Abrams and Guzman 2015; Bogdanovic et al. 2017; McAllister et al. 2015). Delta-9-tetrahydracannabinol (Δ9-THC), cannabidiol (CBD) and cannabigerol (CBG) are known as the major compounds among all phytocannabinoids (Pagano et al. 2021). Cannabinol (CBN), cannabichromene (CBC), cannabidiolic acid (CBDA), cannabinodiol (CBND), cannabielsoin (CBE), cannabicyclol (CBL), cannabitriol (CBT), and cannabidivarin (CBDV) are the other well-known minor phytocannabinoids (Walsh and Holmes 2022). Plasma concentration of Δ9-THC reaches its highest level at 1–6 h after the cannabis ingestion, and its half-life is approximately 20–30 h (Abrams and Guzman 2015). Maximum concentration of Δ9-THC reaches in 2–10 min after the cannabis inhalation and the levels decrease rapidly within 30 min (Abrams and Guzman 2015; Baglot et al. 2021).

2.2 The Endocannabinoid System (ECS)

The endocannabinoid system (ECS) comprises endogenous agonists called “endocannabinoids”, enzymes responsible for synthesizing and degrading endocannabinoids, and cannabinoid (CB) receptors (Lu and Mackie 2021; Pertwee 2012). Endocannabinoids are known as natural lipid mediators found in human body (Lu and Mackie 2021), and best characterized endocannabinoids anandamide (N-arachidonoylethanolamine, AEA) and 2-arachidonoyl glycerol (2-AG) generally act through classical CB1 and CB2 receptors (K. A. Johnson and Lovinger 2016; Martinez-Pena et al. 2021; Wu 2019). Besides CB1/2 receptors, both endogenous and exogenous cannabinoids may interact with other G-protein-coupled receptors, GPCR55, GPCR18, GPCR92 or GPCR12 (Biringer 2021; Irving et al. 2017; Pacher et al. 2020; Starowicz et al. 2007); transient receptor potential vanilloid (TRPV) channels TRPV1 or TRPV2 (Martinez-Pena et al. 2021; Petrosino et al. 2016), and nuclear peroxisome proliferator–activated receptor α (PPARα) (P. Morales and Jagerovic 2020; Muller et al. 2018) to regulate various physiological processes involving hemostasis and energy balance (Bellocchio et al. 2008; Martinez-Pena et al. 2021), appetite (Jager and Witkamp 2014; Wu 2019), memory and learning (Wu 2019), and control in nausea and vomiting (Parker et al. 2011; Sharkey et al. 2014). Anandamide is produced with the catalysis of N-acyl phosphatidylethanolamine (NAPE) by N-acyl phosphatidylethanolamine phospholipase D (NAPE-PLD) (De Petrocellis and Di Marzo 2009; Lu and Mackie 2021; Pyszniak et al. 2016). 2-AG is synthesized by conversion to diacylglycerol by diacylglycerol lipase (DAGL) enzyme, depending on the activation of phospholipase C (PLC) (Battista et al. 2012; De Petrocellis and Di Marzo 2009; Martinez-Pena et al. 2021). Diacylglycerol is generally hydrolyzed with monoacylglycerol lipase (MAGL) or alpha/beta-hydrolase domain containing 6/12 (ABDH6/12) (Grabner et al. 2017; Lu and Mackie 2021; Moreno et al. 2019), and AEA is hydrolyzed by fatty acid amide hydrolase (FAAH) (De Petrocellis and Di Marzo 2009; Massi et al. 2013; Pyszniak et al. 2016). AEA and 2-AG are also hydrolyzed by cyclooxygenases (COX, e.g. COX-2) (Egmond et al. 2021; Lu and Mackie 2021; Maccarrone 2017; Urquhart et al. 2015), lipoxygenases (LOX, e.g. ALOX isoforms) (Egmond et al. 2021; Maccarrone 2017), cytochrome P450 (CYP-450) or monooxygenases as well (Lu and Mackie 2021; Pyszniak et al. 2016; Zelasko et al. 2015) (Fig. 1). AEA, oleoylethanolamide (OEA), and palmitoylethanolamide (PEA) are also hydrolyzed by N-acylethanolamide-hydrolyzing acid amidase (NAAA) (Lu and Mackie 2021; Pagano et al. 2021; Ramer et al. 2019).

Fig. 1
figure 1

Schematic representation of endocannabinoid synthesis and breakdown. ABHD6/12 α/β-hydrolase domain containing protein 6 or 12, COX-2 Cyclooxygenase 2, DAG 1,2 Diacylglycerol, DAGL Diacylglycerol lipase, FAAH Fatty acid amide hydrolase, MAGL Monoacylglycerol lipase, NAAA N-Acylethanolamide-hydrolysing acid amidase, NAPE N-Arachidonoyl phosphatidylethanolamine, NAPE-PLD NAPE phospholipase D, NAT N-Acyltransferase, PLC Phospholipase C

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CB1 receptor is predominantly located in synaptic terminals in hippocampus, basal ganglia, cerebellum, and cerebral cortex in central nervous system (Egmond et al. 2021; Lu and Mackie 2021; Pacher et al. 2020; Smiarowska et al. 2022; Wu 2019), bronchial and bronchiolar epithelia in respiratory system (Boyacıoğlu et al. 2021; Smiarowska et al. 2022), uterus, ovary, follicular fluid, embryo and placenta in female reproductive system (Bilgic et al. 2017; Fonseca et al. 2018; Martinez-Pena et al. 2021; Scotchie et al. 2015), testis, vas deferens and prostate in male reproductive system (du Plessis et al. 2015; Walker et al. 2019), and duodenal subepithelial region in digestive system (Health Canada 2018; Lee et al. 2016; Smiarowska et al. 2022), whereas lymphocytes, monocytes, macrophages, mast cells, and natural killer cells carry CB2 receptor in immune system (Chakravarti et al. 2014; Compagnucci et al. 2013; Lu and Mackie 2021; Martinez-Pena et al. 2021). Our group previously revealed that CB1 and 2 receptors are present in bone marrow mononuclear cells and hematopoietic stem cells (Kose et al. 2018).

CB ligands interact with Gαi/o coupled receptors (Nogueras-Ortiz and Yudowski 2016) that in turn inhibit adenylyl cyclase enzyme, decrease cyclic adenosine monophosphate (cAMP) production, and activate the downstream mitogen-activating protein kinase (MAPK)/phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) pathway, respectively (Abrams and Guzman 2015; Turgeman and Bar-Sela 2019). Those signaling cascades are directly related with cell proliferation, migration, and death balance (Egmond et al. 2021; Howlett 2005). CB1/2 receptor and MAGL gene deletions have been reported to cause a deceleration in the progression of various cancer types, and an increase in their expression might also trigger carcinogenesis (Hinz and Ramer 2019; Moreno et al. 2019) and other pathological conditions such as traumatic brain injury, stroke or drug addiction (D.-j. Chen et al. 2017; Gallego-Landin et al. 2021). CB2 receptor level increases in various neurological diseases such as Alzheimer’s disease (Aso and Ferrer 2016), depression (Onaivi et al. 2008), and Parkinson’s disease (Concannon et al. 2016) when compared to CB1.

2.3 Synthetic Cannabinoids

Synthetic cannabinoids are manufactured as functional analogues of phytocannabinoids and endocannabinoids not only binding to CB1 or CB2 receptors (Egmond et al. 2021; Lim et al. 2021; Mangal et al. 2021; Smiarowska et al. 2022) but also interacting with intracellular survival or apoptotic molecules (Pyszniak et al. 2016). Synthetic cannabinoids are also known as bioactive compounds when compared to natural cannabinoids (Mangal et al. 2021; Morales and Reggio 2019). Synthetic cannabinoid agonists cannot cross the blood–brain barrier despite Δ9-THC (Smiarowska et al. 2022). Non-specific CB1/2 agonists such as WIN55–212-2, HU-210, CP55–940, JWH-018 or KM-233; CB1 agonists like arachidonoylcyclopropylamide (ACPA), arachidonyl-2′chloroethylamide (ACEA) and methanandamide; CB1 antagonists such as SR141716 (also known as Rimonabant), and CB2 agonists such as CB65, JWH-133, and JWH-015 (K. A. Johnson and Lovinger 2016; Khan et al. 2016; Ladin et al. 2016; Pyszniak et al. 2016; Sledzinski et al. 2021; Velasco et al. 2016) have been developed to stimulate CB1/2 receptors pharmacologically. Synthetic cannabinoids have been substantially researched in preclinical studies for their antitumor properties involving suppression of proliferation, angiogenesis, invasion, migration and metastasis and stimulation of autophagy and apoptosis, through binding CB1 or CB2 receptors with a higher affinity (Pyszniak et al. 2016; Sledzinski et al. 2021; Velasco et al. 2016).

2.4 Cannabinoids in Healthy Vs Cancer Cell Behavior

Both endogenous and exogenous cannabinoids have crucial biological roles in many physiological and pathological processes (Shah et al. 2021). Cannabinoid agonists provide intracellular Ca2+ release for vascular (Howlett and Abood 2017), gastric (Mahavadi et al. 2014), and myometrial (Brighton et al. 2009) smooth muscle contraction via Gi/o-dependent PI3K, Src kinase, and extracellular signal-regulated kinase 1/2 (ERK1/2) activation under the regulation of CB1/2 receptors. Those agonists also regulate the reorganization of actin cytoskeleton through focal adhesion kinase (FAK) phosphorylation and Ras-Raf-MEK-ERK1/2 cascade (Dalton et al. 2013). There have been studies revealing their involvement in learning and memory (Smiarowska et al. 2022), circadian rhythm (Vaseghi et al. 2021), regulation of food intake (Silvestri and Di Marzo 2013; Silvestri et al. 2011), and homeostasis (Klumpers and Thacker 2018) and on-going large-scale studies including the use of cannabinoids for their antinociceptive (Good et al. 2019; Häuser et al. 2018; Lichtman et al. 2018), anti-inflammatory (Turcotte et al. 2015), neuroprotective (Minerbi et al. 2019), immunomodulatory (Das et al. 2019), and antiepileptic (Das et al. 2019; Moreno et al. 2019) properties.

The ECS ligands, AEA and 2-AG, or their metabolites may reach detectable picomolar plasma levels providing an equilibrium between the tissues and the circulation (Röhrig et al. 2019). However, they are known to be unstable in circulating system as being catalyzed by ECS enzymes in plasma under physiological conditions (Lanz et al. 2018). Our group also previously showed the presence and concentration of AEA and 2-AG metabolites in healthy rat plasma samples (Ozdurak et al. 2010). On the contrary, altered ECS components including enzymes and receptors are positively correlated with tumorigenesis (Daris et al. 2019; Drozd et al. 2022; Laezza et al. 2020; Pagano et al. 2021). Elevated CB1/2 receptor levels were demonstrated in breast (Caffarel et al. 2010; Pérez-Gómez et al. 2015), endometrial (Thangesweran Ayakannu et al. 2015; Guida et al. 2010), ovarian (Messalli et al. 2014), prostate (Chung et al. 2009; Cipriano et al. 2013; Singh et al. 2020) and non–small cell lung (NSCLC) cancers (Boyacıoğlu et al. 2021; Preet et al. 2011; Xu et al. 2019), melanoma (Carpi et al. 2017; Zhao et al. 2012), and hepatocellular carcinoma (Mukhopadhyay et al. 2015). Reduced protein expressions of NAPE-PLD, FAAH, and/or MAGL (Ramer et al. 2021) were positively correlated with AEA or 2-AG synthesis in colorectal (Chen et al. 2015; Sun et al. 2013), endometrial (Ayakannu et al. 2019), hepatocellular (Zhu et al. 2016) carcinoma, and glioma (Wu et al. 2012). The effect of cannabinoids on cell proliferation, migration, invasion, angiogenesis, autophagy, and death is schematized in Fig. 2 and will be discussed in detail below.

Fig. 2
figure 2

An overview of downstream signaling pathways in a cancer cell by various exogenous and endogenous cannabinoids via CB1, CB2, and TRPV1 receptors. Activation of those cannabinoid and non-cannabinoid receptors stimulates de novo ceramide synthesis which induces endoplasmic reticulum (ER) stress, p8, TRIB3, CHOP, and ATF-4. Activation of TRIB3 and mTORC-2 and inhibition of p-PI3K lead to prevention of Akt phosphorylation and, therefore, cell proliferation. Inhibited p-Akt also decreases mTORC-1 level and induces autophagy in cancer cell. Cannabinoids induce ERK1/2 which triggers p27 and p21 leading to cyclin D and E, cdc2, and cdk2 reduction and cell cycle arrest. Release of Ca2+ stimulates ROS production, activates ER stress, induces NOXA and Bax and mitochondrial cytochrome c release, which activates caspase 9 and 3 leading to apoptosis. Stimulated CB1/2 receptors inhibit invasion and migration by enhancing TIMPs, metastasis by reducing MMP2 and 9, and angiogenesis by inhibiting VEGF and Ang-2. Δ9-THC Delta-9-tetrahydracannabinol, 2-AG 2-Arachidonoylglycerol, ACPA Arachidonoyl cyclopropilamide, AEA Anandamide, Akt Protein kinase B, Ang-2 Angiotensin II, ATF-4 Activating transcription factor-4, Bax Bcl-2-associated X protein, Bcl-2 B-cell lymphoma 2, CaMKKβ Calcium ions/calmodulin-stimulated protein kinase kinase β, cAMP Cyclic adenosine monophosphate, CB1 Cannabinoid receptor 1, CB2 Cannabinoid receptor 2, CHOP C/EBP homologous protein, ERK1/2 Extracellular signal-regulated kinase 1/2, JNK c-Jun N-terminal kinase, MAPK Mitogen-activated protein kinase, MMP-2/9 Matrix metalloproteinase 2/9, mTORC-1/2 Mammalian target of rapamycin C-1/2, NOXA Phorbol-12-myristate-13-acetate-induced protein 1, p21 Cyclin-dependent kinase inhibitor 1, p27 Cyclin-dependent kinase inhibitor 1B, PI3K Phosphoinositide 3-kinase, PKA Protein kinase A, ROS Reactive oxygen species, SMAC Second mitochondria-derived activator of caspase, TIMP Tissue inhibitor of metalloproteinase, TRIB3 Tribbles pseudokinase 3, TRPV1 Transient receptor potential cation channel subfamily V member 1, VEGF Vascular endothelial growth factor, XIAP X-linked inhibitor of apoptosis

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2.4.1 Cannabinoids in Cell Proliferation

Cannabinoids reduce proliferation of various cancer cells through cannabinoid or non-cannabinoid receptor mechanisms. Δ9-THC exerts anti-proliferative effect (Fowler 2015) on A549, H460, H1792, and SW-1573 NSCLC (Baram et al. 2019; Milian et al. 2020; Preet et al. 2008; Sarafian et al. 2008), LNCaP, 22RV1, DU-145, and PC-3 prostate cancer (De Petrocellis et al. 2013), Panc1, Capan2, BxPc3, and MiaPaCa2 pancreatic cancer (Carracedo et al. 2006), HeLa cervical cancer (Ramer and Hinz 2008), U266 and RPMI multiple myeloma (Nabissi et al. 2016), MDA-MB231 breast cancer (Hirao-Suzuki et al. 2019), HL60 acute myeloid leukemia (Katherine A. Scott et al. 2017), T98G, U87MG, and GL261 glioma (López-Valero et al. 2018; Scott et al. 2014), D283, D425, and PER547 medulloblastoma (Andradas et al. 2021), IC-1425EPN and DKFZ-EP1NS ependymoma (Andradas et al. 2021), and SF126, U251, and U87 glioblastoma (Marcu et al. 2010; Torres et al. 2011) cell lines through ERK1/2 activation, PI3K/Akt inhibition and Raf-1 translocation. Non-psychoactive natural CBD inhibits the proliferation of A549, H460, and primary NSCLC (Ramer et al. 2013), SKOV-3 ovarian cancer (Fraguas-Sánchez et al. 2020), MDA-MB231 breast cancer (McAllister et al. 2007; Nallathambi et al. 2018), U878MG, U373MG, SF126, U251, and U87 glioblastoma (Marcu et al. 2010; Singer et al. 2015; Torres et al. 2011), T acute lymphoblastic leukemia and Jurkat (Kalenderoglou et al. 2017), SUM159 triple negative breast cancer (Mohamad Elbaz et al. 2015), SK-N-SH neuroblastoma (Fisher et al. 2016), LNCaP and DU-145 prostate cancer (De Petrocellis et al. 2013), D283, D425, and PER547 medulloblastoma (Andradas et al. 2021), IC-1425EPN and DKFZ-EP1NS ependymoma (Andradas et al. 2021), and CaCo-2 and HCT116 colon adenocarcinoma (Aviello et al. 2012) cells by elevating p53, EGFR, ERK1/2, Akt, and C/EBP homologous protein (CHOP) and/or inhibiting transient receptor potential cation channel subfamily M (melastatin) member 8 (TRPM8). 2-AG and methanandamide reduce viability of PC-3 and primary prostate cancer cells by activating caspase-3 and ERK1/2 levels and by reducing Bcl-2 and Akt levels (Orellana-Serradell et al. 2015). CB1 inverse agonist Rimonabant (SR141716) inhibits proliferation of HCT116 and SW48 colon cancer cells by inducing cytochrome C release and TRAILR-1, −2, and −3 expressions and downregulating Bcl-2 and XIAP (Proto et al. 2017). Rimonabant also shows Wnt/β-catenin-mediated anti-proliferative effect on primary colon cancer stem cells in vitro (Fiore et al. 2018). Non-selective pan CB agonist WIN55,212–2 or JWH-133 has anti-proliferative effect on T98G, LN18, LN229, U251MG, and U87MG glioma cell lines by inducing intrinsic apoptotic pathway and DNA fragmentation (Ellert-Miklaszewska et al. 2021), LNCaP and PC-3 prostate cancer cells by downregulating PI3K/Akt/mTOR cascade (Morell et al. 2016), A549, SW-1573, A459, CALU1, H460 and H1299 NSCLC cells through PI3K/Akt and JNK pathways (Boyacıoğlu et al. 2021; Preet et al. 2011; Ravi et al. 2014; Vidinsky et al. 2012), and 786-O, SMKTR2, SMKT-R3, Caki-2, RCC-6, 769-P, Caki-1, and ACHN human renal carcinoma lines by stimulating cell cycle arrest at G0/G1 phase (Khan et al. 2018). WIN55,212–2 inhibits BEL7402 hepatocellular carcinoma cell line by inducing p27, downregulating cyclin D1 and, therefore, promoting cell cycle arrest at G0/G1 phase and reducing ERK1/2 protein expression (D. Xu et al. 2015). WIN55,212–2 diminishes the viability of A549 NSCLC cells by increasing DNA fragments in nucleus (Müller et al. 2017). Cannflavin A, a compound of Cannabis sativa, reduces the proliferation of T24 and TCCSUP bladder transitional cell carcinoma lines (Andrea M. Tomko et al. 2022). Our group also demonstrated that AEA and 2-AG decrease HEp-2 human laryngeal squamous cancer cell proliferation in vitro (Önay et al. 2022).

2.4.2 Cannabinoids in Cell Migration, Invasion, and Angiogenesis

Tumor growth and expansion are highly dependent on neovascularization, cancer cell migration, and metastasis (Laezza et al. 2020; Wang and Multhoff 2021). Anti-angiogenic, anti-invasive, and anti-metastatic activities of cannabinoids have been extensively tested to block the induction and expansion of tumor growth (Pagano et al. 2021; Ramer et al. 2021; Vecera et al. 2020). Those effects have been associated with various metalloproteinases, inhibitors, and adhesive molecules (Braile et al. 2021; Sledzinski et al. 2018; Wang and Multhoff 2021). JWH-133 prevents angiogenesis and migration of human umbilical vein endothelial cells (HUVECs) by activating tissue inhibitor of matrix metalloproteinases-1 (TIMP-1) besides inducing DNA fragmentation in A549, H460, and/or H358 NSCLC cells (Ramer et al. 2014; Vidinsky et al. 2012). CBD inhibits angiogenesis of HUVECs through vascular endothelial growth factor 1 or 2 (VEGF1/2), angiopoietin-2, urokinase-type plasminogen activator (uPA), and matrix metalloproteinase 2 or − 9 (MMP-2/9) blockage (Solinas et al. 2012). Selective CB1 agonist ACEA and JWH-133 inhibit invasion of U138 glioma cells (Tim Hohmann et al. 2017). Coincubation of selective CB1 receptor antagonist AM281 with ACEA significantly diminishes the invasion of LN229 glioblastoma cell line in vitro (T. Hohmann et al. 2019). CBD inhibits A549, H358, and/or H460 NSCLC cell invasion by decreasing plasminogen activator inhibitor-1 (PAI-1) expression (Ramer et al. 2010b) or by upregulating TIMP-1 (Ramer et al. 2012; Ramer et al. 2010a) or intercellular adhesion molecule-1 (ICAM-1) (Haustein et al. 2014; Ramer et al. 2012) levels. CBD also prevents epithelial growth factor (EGF)-induced migratory ability of 4 T1.2 and SUM159 triple-negative breast cancer by inhibiting MMP-2 and -9 expressions in addition to phosphorylated Akt (p-Akt) and ERK (Elbaz et al. 2015) or Ishikawa, PCEM004a and PCEM004b endometrial cancer lines (Marinelli et al. 2020) in vitro. Anti-invasive and anti-migratory effects of AEA have been revealed in U251 glioma cells in vitro (Ma et al. 2016). FAAH inhibitors arachidonoyl serotonin (AA-5HT) and URB597 diminish A549 cell metastasis and invasion via upregulation of TIMP-1 (Winkler et al. 2016). CB2 receptor agonist JWH-015 reduces migratory and invasive properties of M2-polarized macrophages when co-cultured with A549 NSCLC cells through inhibition of FAK, vascular cell adhesion molecule 1 (VCAM1) and MMP-2 expressions (Ravi et al. 2016). Anti-metastatic property of CBD, Δ9-THC, SR141716A, and/or SR144528 (CB2 receptor antagonist) has been established in MDA-MB231 breast cancer cells via Id1 downregulation (McAllister et al. 2011; Murase et al. 2014) and p-ERK and p38/MAPK upregulation (McAllister et al. 2011). WIN-55, 212–2 inhibits migration and metastasis of SGC7901 and AGS gastric cancer cell lines via COX-2, vimentin, and p-Akt downregulation and E-cadherin upregulation (Xian et al. 2016). Δ9-THC decreases motility of HEC-1B and AN3 CA endometrial cancer cells by inhibiting MMP-9 expression (Zhang et al. 2018) and U266 and RPMI multiple myeloma cells by reducing CXCR4 and CD147 (Nabissi et al. 2016).

2.4.3 Cannabinoids in Cell Autophagy and Death

Cannabinoids activate autophagy and apoptosis through CB1/2 or other non-cannabinoid receptors. Δ9-THC, WIN-55,212–2, and/or JWH-015 stimulate A549 and SW-1573 NSCLC cell apoptosis by inhibiting EGF-induced p-ERK, p-JNK, and p-Akt (Preet et al. 2008; Preet et al. 2011). Δ9-THC, JWH-015, CBD, AEA, and/or Met-F-AEA (combined with URB597) induce apoptosis of U87MG, U118MG, and T98G glioblastoma (Ivanov et al. 2020; Ivanov et al. 2017), A549 NSCLC (Ramer et al. 2013; Ravi et al. 2014), Ishikawa, Hec50co, MFE-280, and/or HEC-1a endometrial cancer (Fonseca et al. 2018; Marinelli et al. 2020), and HepG2 and HuH-7 hepatocellular liver carcinoma (Vara et al. 2011) cell lines through JNK, p38-MAPK phosphorylation, p-Akt inhibition, NF-κB phospho-p65 reduction, caspase-3/−7 activation or COX-2, and PPAR-γ upregulation. Cannflavin A promoted apoptosis of T24 bladder transitional cell carcinoma lines through caspase-3 cleavage in vitro (Tomko et al. 2022). We also previously demonstrated that specific CB1 receptor agonist ACPA induces A549, H1299, H358, and H838 NSCLC cell line apoptosis by inhibiting Akt/PI3K pathway, glycolysis, TCA cycle, amino acid synthesis, and urea cycle and by activating JNK cascade (Boyacıoğlu et al. 2021). LV50, a compound having high affinity to CB2 receptor, promotes apoptosis of Jurkat leukemia cells by inducing cleavage of caspase-3/−8 and PARP (Capozzi et al. 2018). CBD induces apoptosis of HCT116 and DLD-1 colorectal cancer cell lines through ROS-dependent Noxa activation (Jeong et al. 2019).

Autophagy is a self-degradative process involving packaging of cytoplasmic organelles called autophagosome (Chang 2020; Pagano et al. 2021). Cannabinoids are known to stimulate autophagy through various cellular mechanisms including ceramide accumulation by hydrolysis of sphingomyelin or de novo ceramide synthesis (Gómez del Pulgar et al. 2002; Lee et al. 2021; Pagano et al. 2021). Newly synthesized ceramide induces expressions of p38, CHOP, ATF-4, and TRIB3 (see Fig. 2), thus inhibiting PI3K/Akt cascade or activating Ca2+/calmodulin-dependent kinase kinase (CaCMKK) through ER stress (Das et al. 2019; Kabir et al. 2019; Ramer et al. 2021). Δ9-THC stimulates sphingolipid synthesis, dihydroceramide accumulation, and autophagosome and autolysosome production in U87MG glioma cell line (Hernández-Tiedra et al. 2016). CBD activates autophagy in Jurkat, MOLT-3, CCFR-CEM, K562, Reh, and RS4;11 leukemia cell lines via increasing LC3-II expression, damaging permeability of mitochondria and releasing cytochrome c (Olivas-Aguirre et al. 2019). Combined Δ9-THC, CBD, CBG, and CBN treatment induces autophagy of MCF-10A non-cancerous breast cell line by activating lipid synthesis, lysosomal vacuoles, and ER-stress-related chaperone protein glucose-regulated protein 78 (GRP78) expression (Schoeman et al. 2020). ACPA and CB2 receptor agonist GW405833 stimulates autophagy of Panc1 pancreatic cancer cells through AMPK activation and Akt/c-Myc inhibition (Dando et al. 2013). Δ9-THC treatment activates autophagy of CHL-1, A375, and SK-MEL-28 melanoma cells by elevating LC3-positive autophagosome and cytochrome-c levels (Armstrong et al. 2015).

2.5 Preclinical In Vivo Studies and Clinical Status of Cannabinoids

Preclinical in vivo studies show that cannabinoid administration leads to decrease in proliferation, migration, invasion, angiogenesis, autophagy, and death in pancreatic (Aizikovich 2020; Carracedo et al. 2006; Donadelli et al. 2011; Sharafi et al. 2019; Yang et al. 2020), lung (Ramer et al. 2012; Ramer et al. 2013; Ravi et al. 2016; Ravi et al. 2014; Winkler et al. 2016; Yasmin-Karim et al. 2018), breast (Elbaz et al. 2017; McAllister et al. 2011; Murase et al. 2014; Nasser et al. 2011), prostate (De Petrocellis et al. 2013; Morales et al. 2013; Morell et al. 2016; Qiu et al. 2019; Roberto et al. 2019), colorectal (Aviello et al. 2012; Borrelli et al. 2014; Deng et al. 2022; Kargl et al. 2013; Martínez-Martínez et al. 2016; Proto et al. 2017; Romano et al. 2014), brain (Gurley et al. 2012; López-Valero et al. 2018; Scott et al. 2014; Singer et al. 2015) and liver (Vara et al. 2013; Vara et al. 2011) cancers, melanoma (Armstrong et al. 2015; Glodde et al. 2015; Kenessey et al. 2012; Simmerman et al. 2019), multiple myeloma (Barbado et al. 2017), and neuroblastoma (Fisher et al. 2016) through PI3K/AKT/mTOR, ERK/MAPK and/or PAI-1 signaling pathways. Recent reports relating to the cannabinoids in various in vivo cancer models are presented in detail (Table 1).

Table 1 Review of in vivo findings regarding the effects of cannabinoids on different cancer models
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2-AG: 2-Arachidonoyl glycerol; AA-5HT: Arachidonoyl serotonin; ACEA: Arachidonyl-2′chloroethylamide; ACF: Aberrant crypt foci; Akt: Protein kinase B; AM281: CB1-specific antagonist; AMPK: 5’ AMP-activated protein kinase; Bax: Bcl-2-associated X protein; BDS: Botanical cannabinoid extraction; CBD: Cannabidiol; CBG: Cannabigerol; Cyc D1: Cyclin D1; COX-2: Cyclooxygenase-2; CXCR4: C-X-C chemokine receptor type 4; DC: Dendritic cell; EGFR: Epidermal growth factor receptor; ERK: Extracellular signal-regulated kinase; GEM: Gemcitabin; GW9662: PPARγ antagonist; IGF-IR: Type 1 insulin-like growth factor receptor; IL6/10: Interleukin 6/10; iNOS: Inducible nitric oxide synthase; i.p.: intraperitoneal; i.t.: intratumoral; JWH-015: CB2-specific agonist; JWH-133: CB2-specific agonist; KM-233: Synthetic analogue of THC; MDSC: myeloid-derived suppressor cell; Met-F-AEA: Stable analogue of anandamide; MMP2/9: Matrix metalloproteinase 2/9; NFκB: Nuclear factor kappa B; O-1602: Cannabidiol analogue; O-1663: Resorcinol derivative; PAI-1: Plasminogen activator inhibitor-1; PAK1: P21-activated kinase-1; PM49: Synthetic cannabinoid quinone; p.o.: per oral; PPARγ: Peroxisome proliferator-activated receptor γ; p.t.: peritumoral; s.c.: subcutaneous; SR1 (or SR141716): CB1-specific antagonist (Rimonabant), SR144528: CB2-specific antagonist; STAT3: Signal transducer and activator of transcription 3; TIMP-1: Tissue inhibitor of matrix metalloproteinases-1; TNF-α: Tumor necrosis factor-alpha; URB597: FAAH inhibitor; βIII Tub: βIII Tubulin; Δ9-THC: Delta-9-tetrahydracannabinol.

Cannabinoid agonists are currently used in the treatment of obesity (Bi et al. 2020; McClements 2020) and as neuroprotective agents for various diseases (Gado et al. 2019) involving Parkinson’s (Celorrio et al. 2016; Cristino et al. 2020) and Alzheimer’s diseases and multiple sclerosis (Black et al. 2019; Novotna et al. 2011) in the clinic. An attention to the use of cannabinoids for medical applications has grown due to their antinociceptive (Brunetti et al. 2020; Bruni et al. 2018; Good et al. 2019; VanDolah et al. 2019) and antiepileptic (Billakota et al. 2019; Brunetti et al. 2020; VanDolah et al. 2019) effects and the modulatory roles in appetite, nausea, and vomiting (Strouse 2016; VanDolah et al. 2019; White 2019). Dronabinol (Abrams and Guzman 2015; Shah et al. 2020) and nabilone oral capsules (Abuhasira et al. 2018; Shah et al. 2020) have equal potency to cure chemotherapy-related nausea and vomiting when compared to the US Food and Drug Administration (FDA)-approved other antiemetic drugs. Clinical studies reveal the relieving effect of nabiximols, oromucosal spray with THC and CBD as active ingredients, on spasms and neuropathic pain in multiple sclerosis (Abuhasira et al. 2018; Lowe et al. 2021) and improvement in sleep disorders in patients with insomnia (Klumpers and Thacker 2018). FDA-approved Epidiolex, as CBD active ingredient, is currently used for seizures related to Lennox-Gastaut and Dravet syndromes (Abu-Sawwa and Stehling 2020; Levinsohn and Hill 2020; Steele et al. 2019). A phase I/II trial exploring the immune-modulatory and anti-inflammatory potency of CBD showed that it avoids graft versus host disease (GVHD) incidence when administered in addition to standard GVHD prophylaxis (Yeshurun et al. 2014). It is worth noting that SR141716 as an anorectic agent used for the obesity treatment was banned by the FDA due to its severe side effects (Khan et al. 2016; Shah et al. 2019). Studies consisting of the analgesic and anti-epileptic properties of cannabinoids on various diseases are shown in Table 2.

Table 2 Completed clinical cannabinoid trials with their effects on various diseases and related symptoms
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3 Future Perspectives for Cannabinoids as Prospective Agents for Cancer

Phytocannabinoids and endogenous and synthetic cannabinoids have been examined in preclinical research works and clinical trials to assess the therapeutic potential for various diseases including cancers. One of the key pitfalls occurs in the short half-lives and psychotropicity of cannabinoids. Therefore, it is crucial to use anti-cancer cannabinoids effective in triggering intrinsic apoptotic mechanisms at low doses without reaching central nervous system. Natural cannabis derivatives are clinically used for pain relief but the horizon should be expanded on their application as anti-tumor agents. Still, a major gap remains which needs to be filled by new research works to clarify the effects of cannabinoids on the tumor microenvironment. Moreover, outputs of in vitro molecular tests should be translated to in vivo models, since in vitro data does not precise the possible problems within the diseased animal as a whole. Preclinical randomized studies convey the therapeutic performance of cannabinoids on cellular mechanisms. Clinical trials including phase trials provide the assessment of personalized performance of different cannabinoid system agents before translation to clinic. A literature search of clinicaltrials.gov by September 2022 found 77 completed clinical studies about cannabis/cannabinoid use in mental disorders, psychotic disorders, pain, immune system diseases, gastrointestinal diseases, central nervous system diseases and various syndromes including Dravet, Tourette, and Lennox-Gastaut syndromes. In 31 out of 77 (40.26%) studies, cannabinoids were tested for their pain-relieving capability; 24 out of 31 searches have been confirmed in phase II/III clinical trials. Epidiolex, CBD oral solution, was approved by FDA on June 25, 2018, to alleviate the seizures observed in Lennox-Gastaut and Dravet syndromes. On the other hand, depression and suicide in patients caused withdrawal of CB1 antagonist rimonabant from the market. No clinical trial or approval has been reported for cannabinoids as anti-cancer therapeutics. As to future prospects, cannabinoids might be evaluated as potential chemotherapeutic drugs or effective adjunctive therapeutics to be used with chemotherapeutics or other targeted agents. However, further investigations are necessary to clarify the safety and potency of cannabinoids.