CBD reduced breast cancer metastasis in advanced stages of the disease as the direct . CBD increases survival in a syngeneic mouse model of breast cancer. Meanwhile, in vivo study results revealed major increase in survival when . Syngeneic mouse models were created by subcutaneously (s.c.) Remarkably, 5 µg of CBD was found to achieve greater tumor cell killing than 4 Gy of RT. .. death in breast cancer cells by coordinating the cross-talk between. Many studies investigating the effects of cannabinoids on tumor progression . Colitisis induced colon cancer model (Azoxymethane, AOM+dextran sulfate .. that CBD inhibited tumor growth and increased the survival of animals .. and triple negative breast cancer (TNBC), a type of breast cancer which is.
a of CBD breast increases mouse model cancer in syngeneic survival
However, additional experimentation in animals is needed to define the pharmacokinetic properties of cannabinoids before large scale human studies are conducted. Such investigations may identify more clinically convenient routes of administration, establish the extent of drug stability and metabolism while providing clues about potential adverse effects of these agents.
Digestive system cancers include colon, stomach, liver, and pancreatic cancer. In the United States, these combined malignancies account for the highest incidence of cancer besides skin cancer and are the second leading cause of death for both sexes.
In , an estimated , new cases of digestive system cancer will be diagnosed in the US with , estimated deaths Siegel et al. Colorectal cancer CRC is the most lethal type of digestive cancer followed by pancreatic and then liver cancer.
Furthermore, there was a positive correlation between CB2 receptor expression and human colon cancer growth. Hence, the ECS may significantly impact colon tumor progression.
The anti-cancer activities of phyto- and synthetic cannabinoids in colon cancer animal models have also been reported. In chemically-induced azoxymethane AOM colon carcinogenesis, the phytocannabinoids, CBD and Cannabis sativa extract which contains high CBD content, one of the main components of the botanical drug, Nabiximols reduced aberrant crypt foci ACF formation and the number of precancerous polyps and tumors Aviello et al.
Synthetic cannabinoids also showed anti-cancer activity in different animal models. HU, a quinone compound synthesized from cannabidiol, reduced angiogenesis and tumor growth in a HT xenograft model Kogan et al. In nude mice xenografts with HT cells, HU also showed greater inhibition of tumor growth than the clinically utilized chemotherapeutic, doxorubicin Kogan et al.
Moreover, a comparative study utilizing multiple animal models showed that HU exhibited less cardiotoxicity than doxorubicin. This activity was accompanied by reduced inflammation, proliferation, and induction of apoptosis in the tumor tissue Kargl et al.
Although numerous studies tested the effect of cannabinoids and their derivatives in different CRC models, reports that utilize agents which bind selectively to CB1 or CB2 receptors are lacking. As such, the direct role of cannabinoid receptor activation in the context of CRC treatment has not been addressed in vivo.
Conversely, Mukhopadhyay et al. Hence, it is appropriate to investigate whether cannabinoid receptors are suitable targets for treatment of liver cancer. These studies provide strong support that phyto, synthetic, and endogenous cannabinoids confer anti-proliferative effects on liver tumor cells, however, in these reports xenografts are the primary model utilized.
Additional insight would be gained by assessing the effect of cannabinoids on HCC using chemical carcinogenesis models which evaluate tumor growth with clinically relevant carcinogens in their native microenvironment. The ECS plays an active role in pancreatic carcinogenesis. It was reported that CB1 and CB2 receptor expression was elevated in human pancreatic tumors when compared to normal pancreas Carracedo et al. Although the levels of endocannabinoids, AEA, 1-AG, and 2-AG were unchanged in pancreatic cancer compared to normal human pancreas, high levels of CB1 receptor expression and low levels of endocannabinoid degrading enzymes, FAAH and monoacyl glycerol lipase MAGL , were associated with shorter survival Michalski et al.
On the other hand, Carracedo et al. Additionally, WIN, reduced the growth of orthotopically implanted MiaPaCa2 pancreatic tumors and prevented the spread of tumor cells to distal organs Carracedo et al.
In vitro studies showed that the anti-proliferative activity of the cannabinoids was mediated by the activation of CB2 receptors followed by de novo synthesis of ceramide and the induction of ER-stress Carracedo et al. Collectively, the ECS plays an important role in the progression of digestive cancers including colon, liver, and pancreatic cancers. Cannabinoid receptor expression is elevated in tumors when compared to normal tissues, indicating that endogenous cannabinoids have cancer promoting activity.
However, preclinical studies revealed that exogenous synthetic, phyto-, and endo- cannabinoids reduced tumor incidence, growth, and angiogenesis. Although sufficient evidence is not available to explain this effect, these seemingly opposing events may be explained by the biphasic effect of cannabinoids. Further research is required to uncover potential in vivo biphasic effects and determine the optimum drug concentrations needed to prevent pancreatic cancer growth.
Moreover, since the number of pancreatic tumor studies with cannabinoids is extremely limited, more research is required to demonstrate cannabinoid efficacy. Breast cancer is the most commonly diagnosed cancer in women and the second leading cause of female cancer deaths in the United States Siegel et al. Risk factors for developing this type of cancer include: Recent research suggested that cannabinoids and the ECS played a role in breast cancer progression and may possess therapeutic potential Caffarel et al.
Breast cancer can be divided into three sub-types: Cannabinoid receptor expression differs between these breast cancer sub-types. Of interest, a correlation between CB2 receptor expression and breast cancer aggressiveness has been suggested Caffarel et al.
As such, the effects of cannabinoids on breast tumor growth and metastasis using in vivo models has helped elucidate their therapeutic and prognostic potential. CBD was shown to decrease tumor growth in multiple breast cancer models including: CBD significantly decreased the incidence of lung metastasis in TNBC xenograft metastatic and orthotopic mouse models. Furthermore, two of these studies which used genetically engineered and xenograft models proposed that CBD elicited these effects by inhibiting EGFR activation, cytokine secretion, and Akt expression McAllister et al.
In contrast, phytocannabinoids also promoted tumor development. Indeed, phytocannabinoid-induced immune suppression has been reported to be mediated by the CB2 receptor in similar tumor models Zhu et al. Synthetic cannabinoid receptor agonists have also been utilized to elucidate the role of CB1 and CB2 receptors in breast cancer growth.
Additionally, activation of CB2 receptors by a similar compound, JWH, was also found to decrease tumor growth and weight in both, ER- positive and ER- negative orthotopic models Elbaz et al. For the most part, in vivo studies indicate that phyto-, synthetic- and endo- cannabinoids suppress tumor development in hormone receptor positive, EGFR positive and triple negative breast cancer animal models.
However, additional animal studies are needed to understand how cannabinoid regulation of the immune system impacts breast tumor growth. Carcinoma of the prostate is the development of malignant cells within the male reproductive prostate gland.
It is the most commonly diagnosed cancer in all men with an estimated , new cases in Siegel et al. This cancer type is also the second leading cause of cancer deaths in men, which primarily appears to be a result of late detection. Risk factors for developing this disease are advanced age, family history, and race. Cannabinoids and their receptors have shown promise as potential therapeutics in prostate cancer. CB1 and CB2 receptor expression was shown to be elevated in prostate cancer compared to normal prostate tissue and are suggested to be positively correlated with poor disease outcome Sarfaraz et al.
Although numerous studies have evaluated the effect of cannabinoids on prostate cancer in cell culture studies, relatively few reports have determined if these effects occur in in vivo animal models. Di Marzo's group found that cannabis extracts enriched with CBD effectively decreased tumor growth in androgen receptor positive LNCaP xenografts but potentiated tumor growth of androgen receptor negative DU xenografts De et al.
These anti-proliferative effects were examined in vitro and were suggested to be mediated by CB2 induced synthesis of ceramide Olea-Herrero et al. While these studies show a promising role for cannabinoids in targeting prostate cancer, more research is needed to definitively establish cannabinoid efficacy in vivo and the importance of androgen receptor signaling in this system.
Lung cancer is the most deadly neoplasm in both males and females in the United States with a death toll anticipated to exceed , individuals in Siegel et al.
Risk factors for developing this disease are tobacco smoking, genetic predisposition, and exposure to radon gas. Survival figures from this disease powerfully demonstrate the need for novel interventions.
As such, cannabinoids have been evaluated in vivo for their efficacy against lung cancer. CBD administration to mice with A cell xenografts decreased tumor growth, invasion and metastasis Ramer et al. Follow up in vitro experiments using A, H, and H lung cancer cell lines suggested that the anti-metastatic effect of CBD was mediated by upregulation of intracellular adhesion molecule-1 ICAM-1 , an anti-metastatic protein which has been suggested to suppress tumor growth via an immuno-surveillance mechanism Wolfram et al.
In contrast, Zhu et al. Stable analogs of AEA also showed differential effects on lung cancer progression in vivo. The Dubinett group found that met-AEA increased tumor growth in a xenograft and allograft murine model and that COX-2 inhibition abrogated these effects Gardner et al. Conversely, Bifulco et al. These studies suggest that the ECS plays a role in both lung cancer progression and suppression.
Consequently, several of these studies indicate that anti-tumor immunity is suppressed by certain cannabinoids, exacerbating tumor growth in immune-competent animals.
As such, exploring the interplay between the immune system, the ECS and lung cancer development may be critical in determining whether cannabinoids are suitable for lung cancer treatment. Thyroid cancer is the most frequently diagnosed endocrine malignancy in the United States. It is estimated that more than 64, new cases will be identified and deaths will result from this disease Siegel et al.
Although the death rate is relatively low compared to other types of cancer, therapeutic options are needed for aggressive forms of this disease whose lethality is thought to be associated with the differentiation state of the tumor Lee et al. Relatively few studies have examined the effect of cannabinoids on thyroid tumor development in vivo , but these reports showed that the ECS was expressed and was capable of modulating tumor growth Portella et al.
For example, the activity of a variety of ECS modulators was examined in KiMol thyroid cells which generate undifferentiated tumors in xenograft models Bifulco et al. In this study, the endogenously synthesized cannabinoid, 2-AG reduced thyroid tumor development. Also, the metabolically stable molecules, arvanil and met-F-AEA also produced a significant reduction in tumor growth.
The results of this study suggested that manipulation of the EC system was a viable option to prevent propagation of thyroid tumor cells. Additional preclinical studies were conducted with met-F-AEA. Using the xenograft model with KiMol cells it was determined that met-F-AEA prevented thyroid tumor growth and this that effect was reversed by antagonism of the CB1 receptor Bifulco et al.
Other studies with KiMol cells confirmed the anti-tumor activity of met-F-AEA and also indicated that this agent regulated tumor angiogenesis Portella et al. The data collected thus far suggest that synthetic EC system modulators represent novel therapeutic targets for thyroid cancer. However, because of the scarcity of in vivo thyroid cancer studies with cannabinoids, more extensive evaluation is needed to confidently define the role of the ECS in this malignancy. The epidermis is comprised of different cell types including keratinocytes and melanocytes, which are the source of non-melanoma skin cancer NMSC and melanoma, respectively.
Skin cancer is the most common cancer in the United States with approximately 5. Melanoma is more deadly and aggressive than NMSC. It is estimated that over 10, patients will die from melanoma in Siegel et al.
Several in vitro and in vivo studies suggest that the ECS plays a vital role in melanoma and NMSC development and progression reviewed in Soliman et al. In addition, circulating levels of the endocannabinoid, 2-AG, increased in metastatic B16F10 mouse melanoma as well as in patients with metastatic melanoma suggesting a link between the ECS and melanoma progression Sailler et al. Furthermore, in human and murine normal keratinocytes and non-melanoma skin tumors e.
The anti-tumor activity of phyto- and synthetic-cannabinoids against melanoma was reported in different in vivo studies using xenograft tumor models. Synthetic cannabinoids, with different affinities for CB1 and CB2 receptors, have helped to shed light on the potential of targeting CB1 and CB2 receptors in melanoma.
Because the psychotropic effects of WIN,2 are primarily mediated by the CB1 receptor, the anti-tumor effects of the non-psychoactive, CB2 selective cannabinoid, JWH was examined.
JWH was as effective as WIN,2 in inhibiting melanoma tumor growth, suggesting that the anti-tumor activity of cannabinoids was mediated by CB2 receptor activation Naeem et al. Hence, the data generated thus far indicate that cannabinoid receptor agonists may be appropriate therapeutic targets for melanoma.
Newer clinical approaches to combat melanoma involve mobilization of cytotoxic T-cells with monoclonal antibodies such as ipilimumab and nivolumab. Since cannabinoids are known immunomodulators, the effects of cannabinoids on cancer immunosurvailence must be addressed in future studies to have a complete understanding of the therapeutic potential of these molecules.
Several studies report that cannabinoids and endocannabinoids have anti-cancer activity against NMSC via cannabinoid receptor dependent or independent pathways Van Dross et al.
Data from these two different studies indicate that the involvement of ECS in skin cancer development is dependent on the type of the stimulus Zheng et al. The in vivo anti-tumor activities of different synthetic cannabinoids have also been reported. WIN,—2 and JWH reduced the growth, impaired vascularization, and reduced the expression of various pro-angiogenic factors in the murine epidermal tumor cell PDV. C57 xenograft model Casanova et al. It will be important for future investigations to include human NMSC tissue models such as PDX in the examination of cannabinoid activity since many of the existing reports primarily utilize mouse tissue xenograft and carcinogen-induced cancer models.
Human studies that investigate the pharmacotherapeutic benefits associated with the use of cannabinoid ligands focus on reductions in pain, spasticity and cognitive deficits in a number of central and peripheral nervous system disorders Velasco et al. To date only a few cannabis-based pharmacological agents are licensed for clinical use.
The emergence of preclinical studies that demonstrate the anti-tumor effects of cannabinoids are growing in number and have formed the basis of limited clinical studies which are beginning to shed light on the translational value of the preclinical work. Secondary measures were the progression free survival at 6 months and overall survival. Additional study outcomes have not yet been reported. In a case report by Foroughi et al. The tumor regression occurred during the time that cannabis was inhaled by the patients Foroughi et al.
A clear limitation of the current human studies evaluating the anti-cancer effects of cannabinoid compounds is the small patient size. To date, no study findings have been replicated in multiple cohorts. Moreover, the measured outcomes and study designs are often variable across trials, making it difficult to compare their findings.
However, despite these challenges, the evidence generated in these human studies are still informative and, when taken together with the strong in vivo animal data demonstrating anti-tumor effects of cannabinoids, offer promise for a clinical role for cannabinoids in the eradication of tumors.
To gain an understanding regarding the translational and therapeutic potential of cannabinoids, this review focused on examining the overall efficacy of these molecules in animal and human studies. Furthermore, clinical studies evaluating cannabinoid efficacy in human subjects are limited, yet these studies showed that cannabinoids may be safe and effective anti-neoplastics. Because large scale clinical trials are lacking, examining the activity of cannabinoids in clinically translatable animal models such as PDX should be the goal of future research as this approach may provide a more accurate assessment of the therapeutic potential of cannabinoids.
This review also sought to couple in vivo animal studies with in vitro experiments in order to examine proposed cannabinoid mechanisms of action and to identify specific cellular targets. The studies reviewed herein indicate that cannabinoids elicit activity through cannabinoid receptor dependent and independent pathways.
Moreover, processes such as ceramide production, ER-stress, autophagy, angiogenesis and matrix remodeling also appear to regulate the anti-tumor activity of cannabinoids. Hence, these investigations shed light on the role of cannabinoids on tumor growth in vivo and may ultimately pave the way for the development of novel cannabinoid therapeutics for cancer treatment.
DL, ES, LG, and RV contributed to the conception and design of the study, the acquisition of data, and the analysis and interpretation of the data. All authors participated in drafting or revising the manuscript, and all authors approved the final version of the manuscript for submission. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
National Center for Biotechnology Information , U. Journal List Front Pharmacol v. Published online Oct 7. Author information Article notes Copyright and License information Disclaimer. Rukiyah Van Dross ude. This article was submitted to Experimental Pharmacology and Drug Discovery, a section of the journal Frontiers in Pharmacology. Received Jun 30; Accepted Sep The use, distribution or reproduction in other forums is permitted, provided the original author s or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice.
No use, distribution or reproduction is permitted which does not comply with these terms. This article has been cited by other articles in PMC. Abstract Cancer is the second leading cause of death in the United States with 1. Cannabinoids and cancer Cannabinoids are a class of hydrophobic molecules that typically bind to G-protein-coupled cannabinoid receptors, cannabinoid receptor type 1 CB1R or cannabinoid receptor type 2 CB2R. Table 1 Pre-clinical assessment of cannabinoids on tumor development.
Decreased tumor size Galve-Roperh et al. Decreased tumor size Gurley et al. Decreased tumor size Massi et al. Our results suggest that the use of a combination of strategies could allow for greater therapeutic efficacy when using CBDs for cancer treatment. The in vitro study results showing synergistic outcomes when using CBDs in combination with RT are in consonance with previous work highlighted in recent reviews 1 , 2.
In one such previous study, synergy was observed in vivo when using RT with CBDs in the treatment of brain tumors, in a glioma model Over the years, different reports have advocated for investigations of combination therapy approaches where such synergies could be established toward clinical translation 1 , A significant innovation in the approach to leverage CBDs for cancer treatment highlighted by our study is the use of smart biomaterials loaded with CBDs.
In general, smart materials 14 are designed to be sensitive to specific stimuli e. Once activated, they can respond in active ways including changing their structure to deliver payloads e. Advancing a smart CBD cancer therapy approach with smart biomaterials presents a number of advantages toward enhancing therapeutic efficacy. First, the sustained delivery of CBDs via this approach will allow for prolonged exposure of the tumor cells to CBDs with expected enhanced effectiveness in tumor cell kills as seen in our initial results.
Highlighting the viability of such a sustained delivery approach, the US Food and Drug Administration FDA has approved biodegradable disks infused with carmustine for the treatment of brain tumors 27 for greater effective treatment outcomes. Second, the in situ delivery afforded using smart biomaterials allows direct delivery of CBD payloads to the tumor subvolume while minimizing off-target toxicities, as seen with other delivery approaches like oral or intravenous administration.
This could allow for reducing the dose of CBDs used, to further minimize any potential toxicities or side effects which have so far limited clinical translation. CBD receptors are not located in the brainstem areas which control respiration and, therefore, lethal overdoses from CBDs are not common 8 , Nevertheless, there are CBD receptors in other tissues throughout the body, which may lead to toxicities or adverse effects such as tachycardia, hypotension, conjunctival injection, bronchodilation, and decreased gastrointestinal motility.
Site-targeted delivery via SRBs could minimize such adverse effects as well as the psychoactive effects that have limited clinical translation efforts. Ongoing work is focusing on demonstrating this expected toxicity advantage in a large cohort study.
A limitation of the current study is the short-term investigation on the survival. This is partly due to an initial focus to explore and demonstrate feasibility to inform further studies.
With view to clinical translation, further investigations will build on the current work for longer term survival studies employing CBD-loaded smart biomaterials with and without RT.
This will also include investigations of other CBDs besides CBD that have demonstrated potential as anticancer agents but have not been rigorously tested, or have been limited by off-target toxicities, which may be minimized with the use of SRBs. The multifunctional SRBs will be able to ensure geometric accuracy but also sustainably deliver potent CBD payloads directly to the tumor with the anticipated benefits of greater therapeutic efficacy and minimal toxicities.
In the previous clinical trial on brain tumors 3 , CBDs had to be repeatedly administered. Our approach could allow for sustained delivery, which will obviate the need for repeated administration and be more convenient for patients. Illustration of innovative approach with potential to significantly enhance therapeutic efficacy using cannabinoids CBDs.
A Currently used commercially available inert radiotherapy RT biomaterials, e. Such replacement would come at no additional inconvenience to cancer patients. Once in place the SRB can be activated to sustainably release its payload as the polymer coating degrades for greater effective tumor cell kill working in synergy with RT as highlighted by our study results.
The use of smart RT biomaterials for sustained delivery could also integrate the use of NP drones 12 loaded with CBDs that can bind specifically to tumor cells to deliver their potent payloads, enhancing tumor cell kill with minimal off-target distribution. The drone technology could also be designed to target CBDs to CB1-type receptors expressed on the peripheral terminals of nociceptors around the RT planning target volume for CBD-induced analgesia.
It has been shown 29 that CBDs mediate analgesia largely via peripheral type 1 CBD receptors in nociceptors, so such an approach with sustained delivery could also help in pain management for cancer patients. In the US, an increasing number of states have now legalized the use of medical cannabis. This trend has also spread internationally, with more countries recognizing the medicinal components of cannabis and legalizing medical use.
Unfortunately, medical cannabis research has been lagging in animal or human placebo-controlled studies addressing barriers to clinical translation. Viable pathways to clinical translation for cancer treatment should include combination approaches or smart CBD cancer therapy that leverages the antitumor effects of CBDs with high therapeutic efficacy and minimal side effects.
Altogether, our results offer an approach for leveraging the antineoplastic activity of CBDs to achieve enhanced therapeutic efficacy during cancer treatment with the possibility of addressing toxicity concerns that have hampered clinical translation efforts. The potential for using smart RT biomaterials, which integrate enhanced tumor cell killing when combining CBDs with RT, and delivery with smart biomaterials, provide a promising pathway for clinical translation.
To this end, ongoing work is investigating such SRBs loaded with CBDs, which could simply replace currently used inert RT biomaterials during image-guided RT, all at no additional inconvenience to cancer patients.
SY-K designed the work, acquired and analyzed data, and participated in writing the manuscript; MM acquired and analyzed data and revised the manuscript; RM and NS analyzed the CT image data and contributed in revision of the manuscript; RD and AH contributed to the concept and design of the work, reviewed and revised the manuscript; and WN contributed to the concept of the work, reviewed and revised the manuscript. All other authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
National Center for Biotechnology Information , U. Journal List Front Oncol v. Published online Apr Raymond Dabney 6 Cannabis Science, Inc.
Allen Herman 6 Cannabis Science, Inc. Author information Article notes Copyright and License information Disclaimer. This article was submitted to Radiation Oncology, a section of the journal Frontiers in Oncology. Received Jan 16; Accepted Mar The use, distribution or reproduction in other forums is permitted, provided the original author s and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice.
No use, distribution or reproduction is permitted which does not comply with these terms. This article has been cited by other articles in PMC. Abstract Over the years, many in vitro and in vivo studies have shown the antineoplastic effects of cannabinoids CBDs , with reports advocating for investigations of combination therapy approaches that could better leverage these effects in clinical translation.
Introduction Many in vitro and in vivo studies have reported on the antitumorigenic effects of plant-derived cannabinoids CBDs and their synthetic analogs, including effects in inducing apoptosis and inhibiting tumor cell growth and metastasis 1 , 2. Clonogenic Cell Survival Assay A cells from an actively growing monolayer were trypsinized and cells per well were seeded in well plates Corning.
Open in a separate window. Statistical Analysis Log-rank Mantel—Cox test and Gehan—Breslow—Wilcoxon test were performed to analyze statistical significance of the survival assay for in vivo lung cancer model with GraphPad prism software.
Author Contributions SY-K designed the work, acquired and analyzed data, and participated in writing the manuscript; MM acquired and analyzed data and revised the manuscript; RM and NS analyzed the CT image data and contributed in revision of the manuscript; RD and AH contributed to the concept and design of the work, reviewed and revised the manuscript; and WN contributed to the concept of the work, reviewed and revised the manuscript.
Based upon these findings, we expected that synthesis of more active analogues based upon CBD would result in the development of a compound that could produce more robust inhibition of advanced stages of metastasis.
CBD reduces the formation of metastatic foci and increases survival in advanced stages of metastatic progression. A The pictures are representative of tumour formation observed at days 5, 7 and 9. B Seven days after the injection of tumour cells, mice were injected i.
Our past studies McAllister et al. S4A and B suggested the unique activity inhibition of Id1 gene expression of CBD was related to the opened pyran ring, the possession of an extended alkyl side chain and was not due to interactions with the abnormal CBD receptor. While selective activation of CB 2 receptors leads to anti-tumour activity Blazquez et al. We reasoned however that a CB 2 selective cannabinoid agonist, having limited activity at CB 1 receptors psychoactivity , could be developed to target Id1, resulting in a single compound that could efficiently target multiple pathways associated with cannabinoid activity leading to enhanced anti-tumour activity.
Experiments were carried out as previously described McAllister et al. Data represent the mean with corresponding confidence limits for three to six independent determinations. O was previously synthesized in a series of bicyclic resorcinol derivatives that resembled CBD Supporting Information Fig. S4A Wiley et al. It has been previously shown to have lower affinity for CB 1 receptors compared with THC and produces little activity in the tetrad assay measure of psychoactivity in vivo Wiley et al.
In all studies, the drugs were co-administered. The antago nist alone had no significant effects on cell viability Supporting Information Fig.
The ability of the cells to migrate and invade in modified Boyden chambers was then determined. Id2 expression was also determined in 4T1 cells treated with vehicle control , 1. While no reversal of CBD activity was observed using the CB 2 receptor antagonist SR, it was able to partially reverse the inhibitory effects of O Id2 is a marker of good prognosis in breast cancer patients and is specifically up-regulated following inhibition of Id1 expression Itahana et al.
S5C is a primary mechanism that leads to the inhibition of Id1 expression, cell growth, invasion and survival across multiple cancers Ligresti et al.
D A representative example of the Western blot analysis for LC3 is shown. E The number of cells positive for annexin staining after 2 days treatment with 1. A primary mechanism for the anti-tumour activity of the mixed CB 1 and CB 2 receptor agonist THC and CB 2 selective agonists is the up-regulation of the autophagy pathway Velasco et al.
We found that O was 2. Moreover, no overt toxicity was noted with O in the mouse models of metastasis as assessed by weight, appearance and general activity data not shown. O is more potent than CBD at inhibiting breast cancer metastasis. One day after the injection, the tumour-bearing mice were i.
In agreement with our findings in the culture, the anti-metastatic activity of CBD was not affected by co-administration with SR SR2 , whereas the anti-metastatic activity of O was partially reversed by the antagonist. Seven days after i. O produces a significant inhibition of advanced stage breast metastasis. A, B One week after the injection of 4T1 cells, the tumour-bearing mice were injected i. Indicates where one animal responding well to treatment with O based on BLI was removed in order to stain and visualize lung metastatic foci.
We next utilized MDA-MBluc-D3H2LN cells in order to determine whether O would produce robust anti-metastatic activity against a human breast cancer cell line in advanced stages of disease progression. This variant is significantly more aggressive than the parental line with a rapid disease progression with a time course more closely resembling the 4T1 model. Additionally, the expression of luciferase allowed us to assess the activity of the drug treatments longitudinally in real time using BLI and to demonstrate that metastases were present in the lung when the treatment was initiated.
This cell line was therefore significantly less sensitive to the effects of CBD but not O While regression did occur beyond the initial size of the tumour in some mice, the tumour did adapt over time and began to progress again. One mouse, where the tumour was regressing in the lung, was removed from the study to confirm the imaging results by visualizing the lung using an India ink stain and a dissecting microscope Supporting Information Fig.
We therefore initiated treatment with CBD 2 days after mice were i. While CBD inhibited disease progression in a subset of the mice, overall survival was not significantly improved Supporting Information Fig. CBD has been reported to have a wide variety of therapeutic indications and has been shown to be non-toxic, safe and well-tolerated in clinical trials Zuardi, One of the most exciting recent areas of study for the therapeutic application of CBD resides in its ability to decrease cancer cell invasion and metastasis Ligresti et al.
In this investigation, we determined that CBD was effective at inhibiting metastatic progression, leading to prolonged survival in multiple preclinical models of breast cancer. Id1 has been shown to play a key role in mediating breast cancer tumourigenicity and metastasis to the lung Fong et al.
We previously reported that CBD could down-regulate Id1 gene expression in breast cancer cell lines in culture McAllister et al. Here, we demonstrated that treatment with CBD can also lead to the inhibition of Id1 gene expression and tumour cell proliferation in lung metastatic foci in a mouse model of breast cancer.
In addition, ectopic expression of Id1 in breast cancer cells reversed the anti-metastatic activity of CBD. Overall, these data suggest that the anti-metastatic activity of CBD is directly related to the down-regulation of Id1 gene expression; Id1 therefore represents a potential biomarker for predicting whether CBD will be effective at inhibiting tumour progression. Additional mechanisms in vivo that have been implicated in the anti-metastatic activities of CBD include the up-regulation of intercellular adhesion molecule-1 and tissue inhibitor of matrix metalloproteinases-1 in lung cancer Ramer et al.
In contrast to the moderate doses of CBD needed to inhibit metastatic progression, higher doses of CBD have been required to inhibit tumour growth after s. In our previous work, daily administration of CBD only produced a minor delay in primary tumour growth in a model where 4T1 cells where s.
In the present manuscript, we observed no inhibition of primary tumour growth in the orthotopic model where the cells where injected into the MFP and when the mice were treated three times a week with CBD. Taken together, the ability of CBD to inhibit primary tumour growth at the doses evaluated in our current investigation is limited. The differences in the potency of CBD for targeting processes involved in cancer cell growth and survival versus invasion and metastasis may explain why the cannabinoid is less efficient at inhibiting primary tumour growth.
We noted that, in both the orthotopic and the i. This led us to hypothesize that CBD could be effective at inhibiting the growth of secondary tumours even after their initial establishment in the lung.
While CBD was effective at inhibiting metastatic progression even in more advanced stages of the disease, it was not efficacious enough to produce substantial increases in survival at this stage. We therefore underwent a screening strategy of cannabinoid analogues focused on inhibition of Id1, cell proliferation and invasion. We therefore further envisioned a cannabinoid analogue that could target Id1 and activate cannabinoid receptors.
This effect can be reproduced using CB 2 selective agonists, which is an advantage since activation of CB 1 receptors leads to psychotropic effects Salazar et al. We hypothesized that targeting of Id1 expression and cannabinoids receptors with a single compound would result in an even more robust inhibition of advanced stages of metastasis.
Screening a library of resorcinol derivatives, we discovered a cannabinoid analogue O that could activate CB 2 receptors and was more potent at inducing the formation of ROS and inhibiting Id1 expression in comparison to CBD. This activity was not related to the activation of CB 1 , CB 2 or vanilloid receptor 1 similar to the results reported previously in human breast cancer cells Ligresti et al.
Taken together, these studies suggest the existence of a unique intracellular interaction site for CBD that regulates calcium homeostasis, leading to generation of ROS. This activity may be one of the initial events leading to the downstream anti-tumour activity of CBD. In addition to inhibiting Id1 expression, the resorcinol derivate O was also found to be an efficacious CB 2 selective agonist. The ability of O to inhibit breast cancer aggressiveness in the culture and in vivo was partially reversed by a CB 2 receptor antagonist.
CBD did not efficiently activate autophagy and did not induce apoptosis in cell culture at concentrations that produce ROS and target Id1 gene expression. A recent study showed CBD increased autophagy-mediated cell death in breast cancer cells in the culture Shrivastava et al.
However, the concentration of CBD used in the culture to produce this effect was significantly higher approximately three times than that needed to target Id1 gene expression in our investigations.
CBD was also shown to be ineffective at inducing autophagy in vivo when targeting glioblastoma Torres et al. O was significantly more potent and efficacious than CBD in multiple preclinical models of breast cancer. O also produced a significant increase in survival in advanced stages of mouse and human breast cancer metastasis, and in certain instances, O produced regression of established metastatic foci.
We propose that this is the result of efficiently targeting cannabinoid anti-tumour pathways that have been associated with the activity of both CBD and THC. In agreement with this hypothesis, the combined administration of CBD and THC produced a similar magnitude of anti-metastatic activity when compared with O alone.
Orthotopic and i.v. mouse models of breast cancer metastasis were used to test the activity of .. CBD increases survival in a syngeneic mouse. The endogenous cannabinoid anandamide inhibits human breast cancer cell Using a mouse model, we previously determined that metastatic breast cancer cells became Here, we report that cannabidiol (CBD), a cannabinoid with a low -toxicity .. Id1. However, this was associated with moderate increases in survival . Previously, it was showed that cannabinoids inhibit tumor growth and to the blockade of the G2 to mitosis transition and increased the number of cells in G2 that cannabidiol was the most potent inhibitor of breast cancer cell growth. .. (22 ) and (d) reduce bone pain in various preclinical models (22,23).