Therapeutic targeting of HER2-CB2R heteromers in HER2-positive breast cancer.

 Proceedings of the National Academy of Sciences: 116 (6)

“Although human epidermal growth factor receptor 2 (HER2)-targeted therapies have dramatically improved the clinical outcome of HER2-positive breast cancer patients, innate and acquired resistance remains an important clinical challenge. New therapeutic approaches and diagnostic tools for identification, stratification, and treatment of patients at higher risk of resistance and recurrence are therefore warranted.

Here, we unveil a mechanism controlling the oncogenic activity of HER2: heteromerization with the cannabinoid receptor CB2R. We show that HER2 physically interacts with CB2R in breast cancer cells, and that the expression of these heteromers correlates with poor patient prognosis.

The cannabinoid Δ9-tetrahydrocannabinol (THC) disrupts HER2-CB2R complexes by selectively binding to CB2R, which leads to (i) the inactivation of HER2 through disruption of HER2-HER2 homodimers, and (ii) the subsequent degradation of HER2 by the proteasome via the E3 ligase c-CBL. This in turn triggers antitumor responses in vitro and in vivo. Selective targeting of CB2R transmembrane region 5 mimicked THC effects.

Together, these findings define HER2-CB2R heteromers as new potential targets for antitumor therapies and biomarkers with prognostic value in HER2-positive breast cancer.”

https://www.ncbi.nlm.nih.gov/pubmed/30733293

https://www.pnas.org/content/early/2019/02/06/1815034116

“Pharmacological activation of cannabinoid receptors elicits antitumoral responses in different cancer models. Our findings reveal an unprecedented role of CB2 as a pivotal regulator of HER2 pro-oncogenic signaling in breast cancer” http://www.ncbi.nlm.nih.gov/pubmed/25855725
“Extensive preclinical research has demonstrated that cannabinoids, the active ingredients of Cannabis sativa, trigger antitumor responses in different models of cancer. Together, our results suggest that standardized cannabis drug preparations, rather than pure cannabinoids, could be considered as part of the therapeutic armamentarium to manage breast cancer.” https://www.ncbi.nlm.nih.gov/pubmed/29940172
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