Phytochemicals in some foods are a potential source of bioactive safe compounds for cancer chemoprevention and suppression of tumor initiation, promotion, and metastasis. In the present study, we evaluated hot water (HWE), microwaved 50% ethanol (MWE), acidic (ACE), and alkaline (AKE) extracts of the fruitbody (sporocarp) of Hericium erinaceus (Yamabushitake, Lion's Mane) mushrooms for their ability to induce apoptosis (programmed cell death) in U937 human monocytic leukemia cells. Cell culture, cell viability, cytotoxicity, flow cytometry, chromosomal DNA integrity, mitochondrial membrane potential, expression of pro- and anti-apoptotic proteins, and activation and inhibition of caspase assays were carried out to help define the mechanism of observed apoptosis. The aqueous and aqueous/ethanolic extracts were active in all assays, whereas the acidic and alkaline extracts with the similar proximate compositions were both inactive. The results of the bioassays with the active extracts are consistent with an apoptosis mechanism governing suppression of the cell proliferation pathway that involves activation of mitochondria-mediated caspase-3 and caspase-9 but not caspase-8. Proximate analysis of the freeze-dried mushroom powder showed that it contains high amounts of proteins, carbohydrates, and minerals. The results indicate that H. erinaceus mushrooms may have therapeutic potential against human leukemia.

BACKGROUND:Endothelial dysfunction is a fundamental step in the atherosclerotic disease process. Activation or injury of the endothelium leads to a variety of inflammatory disorders, including the release of microparticles. Endothelial progenitor cells may contribute to the maintenance of the endothelium by replacing injured mature endothelial cells.

OBJECTIVE:We studied the influence of dietary fat on the release of endothelial microparticles (EMPs) and endothelial progenitor cells (EPCs) in elderly subjects.

DESIGN:Twenty healthy, elderly subjects (10 men and 10 women) consumed 3 diets following a randomized crossover design, each for 4 wk: a saturated fatty acid diet; a low-fat, high-carbohydrate diet; and a Mediterranean diet (MedDiet) enriched in monounsaturated fatty acids. We investigated total microparticles, EMPs from activated endothelial cells (activated EMPs), EMPs from apoptotic endothelial cells (apoptotic EMPs), EPCs, oxidative stress variables, and ischemic reactive hyperemia (IRH).

RESULTS:The MedDiet led to lower total microparticle, activated EMP, and apoptotic EMP concentrations and higher EPC numbers than did the other diets (P<0.001). We detected lower superoxide dismutase activity (P<0.001), a higher plasmaβ-carotene concentration (P<0.001), and lower urinary isoprostane and plasma nitrotyrosine concentrations after consumption of the MedDiet than after consumption of the other 2 diets (P<0.05). Furthermore, the occurrence of IRH was higher after consumption of the MedDiet than after consumption of the other 2 diets (P<0.05).

CONCLUSION:Consumption of the MedDiet induces a reduction in endothelial damage and dysfunction, which is associated with an improvement in the regenerative capacity of the endothelium, in comparison with 2 other diets.

BACKGROUND:Functional foods are extensively studied for their cancer preventive effects. In the present study, we compared the anti-cancer activity of aqueous extracts of three species of mushrooms including: Pleurotus ostreatus (PAE), Auricularia polytricha (AAE) and Macrolepiota procera (MAE) on COLO-205 cells.

METHODS:Various in vitro approaches were performed to investigate the most potential mushroom variety that possesses maximum cytotoxic, anti-proliferative and apoptosis inducing properties. MTT assay was used to assess cytotoxicity. IC50 values were obtained and further used to perform clonogenic survival, wound scratch and apoptosis assays. Gene expression studies of apoptosis and cell cycle related studies were performed by reverse transcriptase PCR, followed by estimation of DNA content by flow cytometric analysis.

RESULTS:Our study showed that PAE acts as the most prominent inducer of cancer cell death as compared to other species. Therefore, we performed expression studies for apoptosis and cell cycle to understand the genes which are responsible for their profound activities. Expression studies illustrated increased levels of caspase-9 (1 to 2.1, P<0.01), caspase-3 (1 to 1.7, P<0.01) and Bax (1 to 1.4, P<0.05) genes followed by decreased levels of Bcl-2 (1 to 0.44, P<0.05) gene with PAE treatment and this was attributed to the activation of intrinsic pathway. Along with apoptosis, an arrest at Go/G1 phase was observed through flow cytometric analysis followed by increased expression of inhibitors of cyclin dependent kinases (CKIs), p16 (1 to 1.5, P<0.05) and p21 (1 to 2.4, P<0.01).

CONCLUSION:This study exemplifies the effectiveness of PAE and may serve as a potential therapeutic agent.

A novel hemolysin was isolated from the edible mushroom Pleurotus nebrodensis by ion exchange and gel filtration chromatography on DEAE-Sepharose and Sephacryl S-100. The hemolysin from Pleurotus nebrodensis hemolysin (nebrodeolysin) is a monomeric protein with a molecular weight of approximately 27 kDa as determined by gel filtration and SDS-PAGE. Nebrodeolysin exhibited remarkable hemolytic activity towards rabbit erythrocytes and caused efflux of potassium ions from erythrocytes. Subsequently, this hemolysin showed strong cytotoxicity against Lu-04, Bre-04, HepG2, L929, and HeLa cells. It was also found that this hemolysin induced apoptosis in L929 and HeLa cells as evidenced by microscopic observations and DNA ladder, respectively. Moreover, this hemolysin was shown to possess anti-HIV-1 activity in CEM cell culture.

Studies have emphasized an antineoplastic effect of the non-psychoactive, phyto-cannabinoid, Cannabidiol (CBD). However, the molecular mechanism underlying its antitumor activity is not fully elucidated. Herein, we have examined the effect of CBD on two different human breast cancer cell lines: the ER-positive, well differentiated, T-47D and the triple negative, poor differentiated, MDA-MB-231 cells. In both cell lines, CBD inhibited cell survival and induced apoptosis in a dose dependent manner as observed by MTT assay, morphological changes, DNA fragmentation and ELISA apoptosis assay. CBD-induced apoptosis was accompanied by down-regulation of mTOR, cyclin D1 and up-regulation and localization of PPARγ protein expression in the nuclei and cytoplasmic of the tested cells. The results suggest that CBD treatment induces an interplay among PPARγ, mTOR and cyclin D1 in favor of apoptosis induction in both ER-positive and triple negative breast cancer cells, proposing CBD as a useful treatment for different breast cancer subtypes.

Oxidative stress in the central nervous system (CNS) may cause oxidation of lipoprotein particles. The oxidized lipoproteins may damage cellular and subcellular membranes, leading to tissue injury and cell death. Human low-density lipoprotein (LDL) and very low-density lipoprotein (VLDL) are oxidized by transition metal ions, such as Cu2+. Using PC 12 cells, we tested the cytotoxicity of oxidized LDL and VLDL. Cell death was increased in a dose-dependent manner. Antioxidants added to the incubation medium, such as vitamins E or C, or resveratrol showed some protection. Results indicated that oxidized lipoproteins may serve as an oxidative stressor, which may initiate the neuronal cell death leading to the manifestation of Alzheimer disease (AD).

This research examined the antioxidant abilities of peptides derived from the Hericium erinaceus mushroom produced via three microbial proteases (Alcalase®, Neutrase®, and Flavourzyme®) at varying concentrations of 10, 25, and 50 mg mL-1. The H. erinaceus mushroom hydrolysate produced from 10 mg mL-1 Alcalase® with 4 hours' digestion resulted in the highest levels of 2,2'-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS), 2,2-diphenyl-1-picrylhydrazl (DPPH), and nitric oxide (NO) radical scavenging activities. Fractionation of this particular hydrolysate was then performed by ultrafiltration (10, 5, 3, and 0.65 kDa molecular weight cut-off membranes). The MW<0.65 kDa fraction demonstrated the highest level of radical scavenging activity in the context of ABTS, DPPH, and NO. Therefore, the fraction MW<0.65 kDa was performed with RP-HPLC to obtain the four principal fractions termed F1-4. The results reveal that the F4 sub-fraction demonstrated the best radical scavenging ability. Additionally, the F4 sub-fraction was able to reduce the potential for DNA damage caused by hydroxyl radicals. This was revealed by testing using the Fenton reaction and the pUC19, pKS, and pBR322 plasmids. This outcome was demonstrated through in vitro antiproliferative activity in human lung carcinoma cell lines (Chago-K1) using MTT assay. The F4 sub-fraction was also demonstrated to induce apoptosis, as indicated using the FITC Annexin V apoptosis detection kit with PI. Furthermore, it was also found that the activity of caspase-3, -8, and -9 in Chago-K1 cells was enhanced after exposure periods of 24 and 48 hours. Finally, this sub-fraction was selected for peptide sequencing via quadrupole-time-of-flight-electron spin induction-mass spectrometry-based de novo peptide sequencing.

Curcuma longa has long been used in China and India as anti-inflammatory agent to treat a wide variety of conditions and also as a spice for varied curry preparations. The chemoprofile of the Curcuma species exhibits the presence of varied phytochemicals with curcumin being present in all three species but AA only being shown in C. longa. This study explored the effect of a curcumin/AA combination on human cancer cell lines. The curcumin/AA combination was assessed by isobologram analysis using the Loewe additivity drug interaction model. The drug combination showed additive cytotoxicity toward CCRF-CEM and CEM/ADR5000 leukemia cell lines and HCT116p53(+/+) and HCT116p53(-/-) colon cancer cell line, while the glioblastoma cell lines U87MG and U87MG.ΔEGFR showed additive to supra-additive cytotoxicity. Gene expression profiles predicting sensitivity and resistance of tumor cells to induction by curcumin and AA were determined by microarray-based mRNA expressions, COMPARE, and hierarchical cluster analyses. Numerous genes involved in transcription (TFAM, TCERG1, RGS13, C11orf31), apoptosis-regulation (CRADD, CDK7, CDK19, CD81, TOM1) signal transduction (NR1D2, HMGN1, ABCA1, DE4ND4B, TRIM27) DNA repair (TOPBP1, RPA2), mRNA metabolism (RBBP4, HNRNPR, SRSF4, NR2F2, PDK1, TGM2), and transporter genes (ABCA1) correlated with cellular responsiveness to curcumin and ascorbic acid. In conclusion, this study shows the effect of the curcumin/AA combination and identifies several candidate genes that may regulate the response of varied cancer cells to curcumin and AA.

BACKGROUND/AIM:Curcumin (CUM) is a promising agent in complementary oncology. The present study analyzed the photoactive properties of curcumin on pediatric epithelial liver tumor cell lines.

MATERIALS AND METHODS:Hepatoblastoma cell lines (HuH6, HepT1) and hepatocellular carcinoma cell lines (HepG2, HC-AFW1) were treated with curcumin and exposed to blue light (phototherapy, 480 nm, 300 W). Cell viability (MTT tests), cellular oxidative stress (production of reactive oxygen species (ROS)) and cellular uptake/degradation of curcumin were analyzed.

RESULTS:Significant loss of viability resulted from 24-48 h incubation with curcumin. With photodynamic therapy (PDT), even short time incubation (1 h) with curcumin resulted in significantly lower half maximal inhibitory concentration (IC50) (p<0.001, two-way ANOVA). Significant ROS production was observed with PDT and curcumin.

CONCLUSION:Phototherapy strongly enhances the anticancer properties of curcumin in pediatric solid liver tumors in vitro.

BACKGROUND/AIM:Curcumin (CUM) is a promising agent in complementary oncology. The present study analyzed the photoactive properties of curcumin on pediatric epithelial liver tumor cell lines.

MATERIALS AND METHODS:Hepatoblastoma cell lines (HuH6, HepT1) and hepatocellular carcinoma cell lines (HepG2, HC-AFW1) were treated with curcumin and exposed to blue light (phototherapy, 480 nm, 300 W). Cell viability (MTT tests), cellular oxidative stress (production of reactive oxygen species (ROS)) and cellular uptake/degradation of curcumin were analyzed.

RESULTS:Significant loss of viability resulted from 24-48 h incubation with curcumin. With photodynamic therapy (PDT), even short time incubation (1 h) with curcumin resulted in significantly lower half maximal inhibitory concentration (IC50) (p<0.001, two-way ANOVA). Significant ROS production was observed with PDT and curcumin.

CONCLUSION:Phototherapy strongly enhances the anticancer properties of curcumin in pediatric solid liver tumors in vitro.

BACKGROUND AND OBJECTIVES:Our group recently synthesized a new, low-cost photosensitizer, chlorophyllin f. In this study, the effects of chlorophyllin f-mediated photodynamic therapy (PDT) and its potential mechanisms were examined in human bladder cancer cells.

MATERIALS AND METHODS:MitoTracker® Green probe and LysoTracker® Green probe were used to label mitochondria and lysosomes, revealing the intracellular localization of chlorophyllin f in 5637 and T24 cells by confocal laser scanning microscopy (CLSM). The cells were treated with chlorophyllin f-mediated PDT; the photo-cytotoxicityof chlorophyllin f was monitored using the Cell Counting Kit-8 assay, and apoptosis was measured by Annexin V-FITC/PI dual staining. Western blotting, transmission electron microscopy (TEM), and staining with Cyto-ID® Autophagy Detection dye, monodansylcadaverine (MDC) and acridine orange were performed to assess autophagy. The role of autophagy was examined by measuring cell viability and apoptosis in both cell lines pretreated with the autophagy inhibitor 3-methyladenine (3-MA).

RESULTS:Chlorophyllin f showed affinity for mitochondria and lysosomes. It exhibited significant photocytotoxicity, resulting in a maximum of 86.51% and 84.88% cell death in 5637 and T24 cells, respectively. Additionally, chlorophyllin f-mediated PDT (f-PDT) also induced a significantly higher percentage of apoptosis in treated cells compared to the control groups (P < 0.05). Moreover, the expression of Beclin1 protein and the proportion of LC3-II:LC3-I in both cell lines significantly increased after f-PDT. Autophagy, characterized by an increase in the formation of Cyto-ID® Autophagy Detection dye-labeled autophagosomes, MDC fluorescent dye-labeled autophagic vacuoles and acridine orange-labeled acidic vesicular organelles (AVOs), was observed in f-PDT-treated cells. TEM also revealed double-membrane autophagosome structures 1 hour after f-PDT. Most importantly, when pretreated with 3-MA, the two cell lines showed more significant photo-cytotoxicityand apoptotic cell death compared to those exposed to f-PDT alone (P < 0.05).

CONCLUSION:Chlorophyllin f-mediated PDT exerts anti-tumor activity by inducing apoptosis and autophagy, and most importantly, autophagy inhibition enhances f-PDT-mediated apoptotic cell death. These results suggest that chlorophyllin f is a new, effective photosensitizer and that the combination of f-PDT with autophagy inhibitors may be an attractive therapeutic strategy against human non-muscle invasive bladder cancer.

Breast cancer (BC) is the foremost cause of cancer-related mortality in women worldwide. Polyporus umbellatus is a polysaccharide preparation of the Chinese traditional herb medicine, which has been explored as an inhibitory compounds in suppressing many cancers. And AKT has been known as an essential signaling pathway to regulate cell proliferation and apoptosis via Mdm2/p53 and Caspase-3 signaling pathways respectively. In our study, western blot, RT-PCR, immunochemical assay, immunofluorescence as well as flow cytometry were performed in vitro or in vivo to determine the effects of Polyporus umbellatus on the progression of human laryngeal cancer. First, the breast cancer cell growth, invasion and migration were inhibited, as well as the tumor volume in nude mice was down-regulated for Polyporus umbellatus use. Additionally, our data also showed that Polyporus umbellatus suppressed breast cancer cells proliferation, which was linked with the down-regulation of AKT activation by Polyporus umbellatus treatment. Mdm was inactivated while p53 was stimulated for Polyporus umbellatus administration, displaying inhibitory role in tumor growth. Furthermore, Polyporus umbellatus could up-regulate breast cancer cells in G0/G1 phase during cell cycle, and at the same time reducing cells in S phase. Also, flow cytometry and western blot assays suggested that apoptosis was induced by the administration of Polyporus umbellatus, which enhanced Caspase-3 expressions by AKT-regulated anti-apoptotic and pro-apoptotic signals. In conclusion, our data indicated that Polyporus umbellatus had a potential role in controlling human breast cancer through inhibiting tumor cell proliferation, inducing apoptosis regulated by AKT, which might provide a therapeutic strategy for breast cancer suppression in the future.

polysaccharide (GLP) is a well-known traditional Chinese medicine, known for its anti-cancer and immunomodulatory properties. The present study aims to investigate whether GLP has a therapeutic effect on hepatocellular carcinoma (HCC) cells exposed to radiation. Immunofluorescence was used to detect the nuclei, the protein expression was measured by western blot analysis and flow cytometry was used to detect the rate of cell apoptosis. GLP treatment was demonstrated to enhance radiation-induced growth inhibition and apoptotic death of HCC cells. At a molecular level, GLP suppressed the activities of DNA repair-associated proteins including ataxia-telangiectasia mutated (ATM) and DNA dependent-protein kinase (DNA-PK) in liver cancer cells under radiation conditions. Furthermore, the addition of an Akt inhibitor elevated the activities of DNA-PK and ATM and attenuated the GLP-induced HepG2 cell injury under the radiation condition. In conclusion, the present study demonstrates that GLP enhances the radiosensitivity of HCC cells via the regulation of Akt signaling pathways, implying a potential therapeutic effect of GLP as a radiation sensitizer in HCC treatment.

is a popular traditional Chinese medicine used in China to improve health. Previous researches have revealed that the polysaccharide fromcould exert diversity activities, including immunomodulation, antioxidant, and antitumor effects. However, the effect of enzymatically hydrolyzedpolysaccharide (EGLP) in colorectal cancer (CRC) progression remains unknown. The present research aimed to investigate the antitumor mechanism of EGLP in human colon cancer cells. For this purpose, the cytotoxic effects of EGLP were measured by the (3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di-phenytetrazoliumromide (MTT) method. The apoptosis was evoked upon EGLP treatment, which was assayed using flow cytometry. The results indicated that EGLP may induce apoptosis in human colon cancer cell (HCT-116) cells via the upregulation of BCL-2 associated X protein (Bax), phospho-extracellular regulated protein kinases (P-ERK), and cleaved caspase-3 expression and downregulation of B-cell lymphoma-2 (Bcl-2), phospho-serine/threonine kinase 1 (p-Akt1), and cyclo-oxygen-ase (COX-2) expression. The obtained findings indicated EGLP as a new therapeutic agent in fighting CRC.

The() mushroom is one of the most extensively studied functional foods, known for its numerous health benefits, including the inhibition of tumor cell growth. The present study assessed the anti-proliferative and pro-apoptotic activity of a novelpolysaccharide peptide (GL-PP) in human glioma U251 cells, which was purified from grass-cultured. GL-PP is a glycopeptide with an average molecular weight of 42,635 Da and a polysaccharide-to-peptide ratio of 88.70:11.30. The polysaccharides were composed of l-arabinose, d-mannose and d-glucose at a molar ratio of 1.329:0.372:2.953 and a total of 17 amino acids were detected. The results of the current study demonstrated that GL-PP significantly inhibited U251 cellular proliferation. The proportion of G/Gphase cells and sub-Gphase cells significantly increased as the concentration of GL-PP increased, as did the activity of caspase-3. These results indicate that GL-PP directly inhibited human glioma U251 proliferation by inducing cell cycle arrest and promoting apoptosis.

No Abstract Available

Ascorbic acid (A) has been demonstrated to exhibit anti-cancer activity in association with chemotherapeutic agents. Potassium (K) is a regulator of cellular proliferation. In the present study, the biological effects of A and K bicarbonate, alone or in combination (A+K), on breast cancer cell lines were evaluated. The survival of cancer cells was determined by sulforhodamine B cell proliferation assay, while analysis of the cell cycle distribution was conducted via fluorescence-activated cell sorting. In addition, the expression of signaling proteins was analyzed upon treatment. The results indicated that there was a heterogeneous response of the different cell lines to A and K, and the best effects were achieved by A+K and A treatment. The interaction between A+K indicated an additive or synergistic effect. In addition, A+K increased the percentage of cells in the sub-G1 phase of the cell cycle, and was the most effective treatment in activating the degradation of poly(adenosine diphosphate-ribose) polymerase-1. In the breast cancer cell line MCF-7, A+K induced the appearance of the 18 kDa isoform of B-cell lymphoma-2-associated X protein (Bax), which is a more potent inducer of apoptosis than the full-length Bax-p21. The effects of A and K on the phosphorylation of extracellular signal-regulated kinase (ERK)1 and ERK2 were heterogeneous. In addition, treatment with K, A and A+K inhibited the expression of nuclear factor-κB. Overall, the results of the present study indicated that K potentiated the anti-tumoral effects of A in breast cancer cells in vitro.

We have previously shown that broccoli sprouts are a rich source of chemopreventive isothiocyanates, which potently induce carcinogen-detoxifying enzymes and inhibit the development of mammary and skin tumors in rodents. However, the principal isothiocyanate present in broccoli sprout extracts, sulforaphane, not only induces carcinogen-detoxifying enzymes but also activates apoptosis and blocks cell cycle progression. In this article, we show that an aqueous extract of broccoli sprouts potently inhibits the growth of human bladder carcinoma cells in culture and that this inhibition is almost exclusively due to the isothiocyanates. Isothiocyanates are present in broccoli sprouts as their glucosinolate precursors and blocking their conversion to isothiocyanates abolishes the antiproliferative activity of the extract. Moreover, the potency of isothiocyanates in the extract in inhibiting cancer cell growth was almost identical to that of synthetic sulforaphane, as judged by their IC50 values (6.6 versus 6.8 micromol/L), suggesting that other isothiocyanates in the extract may be biologically similar to sulforaphane and that nonisothiocyanate substances in the extract may not interfere with the antiproliferative activity of the isothiocyanates. Further study showed that the isothiocyanate extract of broccoli sprouts activated the mitochondria-mediated apoptosis pathway and halted cells in S and M phases. Cell cycle arrest was associated with down-regulation of Cdc25C and disruption of mitotic spindles. These data show that broccoli sprout isothiocyanate extract is a highly promising substance for cancer prevention/treatment and that its antiproliferative activity is exclusively derived from isothiocyanates.

BACKGROUND:Although several therapeutic options are currently available for patients with various cancers, the outcomes are often disappointing and a more effective modality needs to be promptly established. We have been exploring an alternative approach using natural agents and two bioactive mushroom extracts isolated from Phellinus linteus (PL), namely PL-ES and PL-I-ES, were of our interest. As anticancer effects of similar extracts have been reported in several cancers, we investigated whether PL-ES and PL-I-ES might have such anticancer activities on a variety of human cancer cells in vitro.

METHODS:Ten different types of human cancer cell lines, including three metastatic prostate, bladder, kidney, lung, breast, stomach, liver, and brain cancer cells, were employed and tested with PL-ES or PL-I-ES. Cell growth/viability, exertion of oxidative stress, and induction of apoptosis were assessed by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide) assay, lipid peroxidation (LPO) assay, and specific enzymatic assay, respectively.

RESULTS:PL-ES (100µg/mL) exhibited potent anticancer activity, resulting in a significant (40-80%) growth reduction in all 10 cancer cells at 72 hours. PL-I-ES (100 µg/mL) was effective on only four cancer cells but its higher concentration at 250 µg/mL led to a significant (25-90%) growth reduction in seven cancer cells. LPO assays indicated that such a significant growth reduction by PL-ES (100 µg/mL) or PL-I-ES (100 or 250 µg/mL) could result from cell death due to a cytotoxic effect of oxidative stress (through free radicals). Moreover, enzymatic assays for caspase-3 (Csp-3) and caspase-9 (Csp-9), thepro-apoptotic regulators, showed that both enzymes were significantly activated by PL-ES or PL-I-ES, indicating that cell death due to oxidative stress was more likely associated with apoptosis.

CONCLUSIONS:The present study shows that both PL-ES and PL-I-ES indeed have anticancer effects on a variety of cancer cells, although PL-ES appears to be more potent than PL-I-ES. Such an anticancer effect is presumably attributed to oxidative stress, which will ultimately lead to apoptosis. Therefore, these two bioactive mushroom extracts may have clinical implications in a more effective therapeutic option for a variety of human malignancies.

Cancer is the second leading cause of death in the United States with 1.7 million new cases estimated to be diagnosed in 2016. This disease remains a formidable clinical challenge and represents a substantial financial burden to the US health care system. Therefore, research and development of novel therapeutics for the treatment of cancer is of high priority. Cannabinoids and their derivatives have been utilized for their medicinal and therapeutic properties throughout history. Cannabinoid activity is regulated by the endocannabinoid system (ECS), which is comprised of cannabinoid receptors, transporters, and enzymes involved in cannabinoid synthesis and breakdown. More recently, cannabinoids have gained special attention for their role in cancer cell proliferation and death. However, many studies investigated these effects using in vitro models which may not adequately mimic tumor growth and metastasis. As such, this article aims to review study results which evaluated effects of cannabinoids from plant, synthetic and endogenous origins on cancer development in preclinical animal models and to examine the current standing of cannabinoids that are being tested in human cancer patients.