Archive for the ‘Breast Cancer’ Category

It has been recently shown that cannabinoids, the active components of marijuana and their derivatives, inhibit cell cycle progression of human breast cancer cells. Here we studied the mechanism of Delta(9)-tetrahydrocannabinol (THC) antiproliferative action in these cells, and show that it involves the modulation of JunD, a member of the AP-1 transcription factor family. THC activates JunD both by upregulating gene expression and by translocating the protein to the nuclear compartment, and these events are accompanied by a decrease in cell proliferation. Of interest, neither JunD activation nor proliferation inhibition was observed in human non-tumour mammary epithelial cells exposed to THC. We confirmed the importance of JunD in THC action by RNA interference and genetic ablation. Thus, in both JunD-silenced human breast cancer cells and JunD knockout mice-derived immortalized fibroblasts, the antiproliferative effect exerted by THC was significantly diminished. Gene array and siRNA experiments support that the cyclin-dependent kinase inhibitor p27 and the tumour suppressor gene testin are candidate JunD targets in cannabinoid action. In addition, our data suggest that the stress-regulated protein p8 participates in THC antiproliferative action in a JunD-independent manner. In summary, this is the first report showing not only that cannabinoids regulate JunD but, more generally, that JunD activation reduces the proliferation of cancer cells, which points to a new target to inhibit breast cancer progression.Oncogene advance online publication, 5 May 2008; doi:10.1038/onc.2008.145.

Initial Award Abstract (2006)
An anti-cancer agent with a low toxicity profile that can both inhibit cancer cell growth and metastasis would be extremely valuable clinically. We have discovered that cannabidiol (CBD), a non-psychotropic cannabinoid constituent of the plant Cannabis sativa, can inhibit the growth, migration and invasion of aggressive breast cancer cells in culture. Cannabinoid compounds, in general, have low toxicity profiles. Furthermore, our preliminary research demonstrated that CBD is a novel inhibitor of a protein whose activity has been closely linked to the aggressiveness of human breast cancers; called inhibitor of DNA binding-1 (Id-1). Whether CBD can inhibit the spread of metastatic breast cancer in vivo (in the body), compared to cell culture conditions, has not been determined. However, CBD has been demonstrated to inhibit aggressive human brain cancers in vivo. Understanding the mechanisms behind the anti-cancer activity of CBD may lead to the validation of new biological targets for diagnostics and therapies for breast cancer. To study the effects of CBD on the growth and spread of aggressive breast cancer, we will use time lapse microscopy to capture detailed changes in cell growth/death, migration, and morphology. Classical biochemical measures of cell growth/death and invasion will also be used in combination with novel compounds to identify receptors that CBD interacts with to produce its anti- breast cancer effects. A mouse model of breast cancer metastasis will be used to determine whether CBD effectively reduces the spread of aggressive breast cancer in vivo. At the intracellular level, we will study whether CBD, (1) regulates Id-1 in an extracellular signal-regulated kinase-dependent manner, and (2) serves to activate a pro-apoptotic (cell death) pathway in a caspase-dependent manner. Novel and effective non-toxic therapies for aggressive breast cancers are urgently required. Plant cannabinoids are compounds that are well tolerated during chronic (long-term) administration. CBD, and compounds based on its structure, may be the basis for the treatment of metastatic breast cancer. If successful, our studies will set the stage for additional translational work to develop CBD’s eligibility for clinical trials.

Final Report (2008)
We discovered that cannabidiol (CBD), a non-psychotropic compound from the plant Cannabis sativa, can inhibit the process of breast cancer cells that allow them to grow and spread (metastasis). CBD can also inhibit breast cancer metastasis in a mouse model. The research carried out in our CBCRP proposal demonstrated that CBD is a novel inhibitor of a gene whose activity is intimately linked to the aggressiveness of human breast cancers; this gene has been termed Id-1. Notably, our findings also indicated that Id-1 was a key gene whose expression needed to be reduced in order for CBD to inhibit aggressive breast cancer. One of the most significant high risk components of the initial application was to determine if CBD had appreciable efficacy against breast cancer in vivo (i.e., animal models). This high risk component was not pursued, since an independent group showed CBD was able to inhibit metastasis of MDA-MB231 cells to the lung of nude mice. Building of the previous findings, we made small structural changes to CBD that are expected to produce drugs that are much more active than CBD at inhibiting Id-1 and corresponding aggressive breast cancers. CBD has a low toxicity profile. An anticancer agent with a low toxicity profile that can both inhibit cancer cell growth and metastasis would be extremely valuable clinically. Understanding the mechanisms behind the anticancer activity of CBD may also lead to the discovery of new biological targets for the development of diagnostic tools and additional therapies for the treatment of cancer. In this project we found portions of the CBD structure essential to its biological activity for breast cancer cell growth inhibition. We are in the process of filing a patent on these discoveries. In addition, we studies the moleculr mechanisms that underlie CBD activity, and found that sustained upregulation of Erk (extracellular signal-regulated kinases, a type of protein kinase intracellular signaling molecules) is key to the ability of CBD to regulate the metastasis-specific inhibition of the Id-1 transcription factor.

Symposium Abstract (2007)
The spread (metastasis) of aggressive breast cancer cells to other parts of the body is the final and fatal step during cancer progression. Clinically, there are still limited therapeutic interventions for aggressive breast cancers available. Clearly, effective and non-toxic therapies are urgently required. The Id-1 gene, a helix-loop-helix type transcription factor, has recently been shown to be a key regulator of the metastatic potential of breast and additional cancers. We previously determined that aggressive breast cancer cells became significantly less invasive in vitro (in culture) and less metastatic in vivo (in mice) when Id-1 expression was reduced using a technique called gene antisense therapy. It is not possible at this point, however, to use this technology to reduce Id-1 expression in patients with metastatic breast cancer. In our search for a non-toxic drug that could inhibit Id-1 expression, a potential candidate agent was discovered. Here we report that cannabidiol (CBD), a compound extracted from cannabis and with a low toxicity profile, can down-regulate Id-1 expression in aggressive human breast cancer cells. The CBD concentrations effective at inhibiting Id-1 expression correlated with those used to inhibit the proliferative and invasive characteristics of aggressive breast cancer cells. CBD was able to inhibit Id-1 expression at the mRNA and protein level in a concentration-dependent fashion. Most importantly, constitutive expression of Id-1 in breast cancer cells abolished the effects of CBD on cell invasiveness. This suggests that Id-1 is indeed a key factor whose expression needs to be down-regulated in order to observe the effects of CBD on the reduction of breast cancer cell aggressiveness. In conclusion, CBD represents the first non-toxic drug that can significantly decrease Id-1 expression in metastatic breast cancer cells leading to reduction of tumor aggressiveness. CBD and additional analogs based off its structure could be used as inhibitors of Id-1 and might be of benefit for patients with breast cancers. Cannabinoids are already being used in clinical trials for purposes unrelated to their anticancer activity and these compounds have been reported to be well tolerated. We expect that using CBD as a template will lead to the discovery of more potent and efficacious drugs. This research could lead to a new area of investigation in the treatment of aggressive forms of breast cancer with novel cannabinoid compounds.

Cannabinoids have been reported to possess antitumorogenic activity. Not much is known, however, about the effects and mechanism of action of synthetic nonpsychotic cannabinoids on breast cancer growth and metastasis. We have shown that the cannabinoid receptors CB1 and CB2 are overexpressed in primary human breast tumors compared with normal breast tissue. We have also observed that the breast cancer cell lines MDA-MB231, MDA-MB231-luc, and MDA-MB468 express CB1 and CB2 receptors. Furthermore, we have shown that the CB2 synthetic agonist JWH-133 and the CB1 and CB2 agonist WIN-55,212-2 inhibit cell proliferation and migration under in vitro conditions. These results were confirmed in vivo in various mouse model systems. Mice treated with JWH-133 or WIN-55,212-2 showed a 40% to 50% reduction in tumor growth and a 65% to 80% reduction in lung metastasis. These effects were reversed by CB1 and CB2 antagonists AM 251 and SR144528, respectively, suggesting involvement of CB1 and CB2 receptors. In addition, the CB2 agonist JWH-133 was shown to delay and reduce mammary gland tumors in the polyoma middle T oncoprotein (PyMT) transgenic mouse model system. Upon further elucidation, we observed that JWH-133 and WIN-55,212-2 mediate the breast tumor-suppressive effects via a coordinated regulation of cyclooxygenase-2/prostaglandin E2 signaling pathways and induction of apoptosis. These results indicate that CB1 and CB2 receptors could be used to develop novel therapeutic strategies against breast cancer growth and metastasis. [Mol Cancer Ther 2009;8(11):3117–29]