Panoply™ Human CNR1 Over-expressing Stable Cell Line

Cannabidiol (CBD), a major component of industrial hemp and cannabis, has a wide range of pharmacological effects on various diseases, including cancer. Furthermore, the potent multikinase inhibitor cabozantinib has been approved for the treatment of advanced hepatocellular carcinoma (HCC). In recent years, research has increasingly focused on the use of cabozantinib combination therapy to improve patient efficacy and safety. Here, researchers investigated the effects of cabozantinib and CBD combination therapy on HCC cells. CBD treatment enhanced the sensitivity of HCC cells to cabozantinib-mediated anticancer activity by increasing cytotoxicity and apoptosis. Phosphokinase array analysis revealed that the apoptotic effect of the combination therapy was primarily related to endoplasmic reticulum (ER) stress-regulated p53 phosphorylation, compared to other kinases. Notably, the effects of the combination therapy were independent of the cannabinoid receptor 1 (CNR1) and CNR2 signaling pathways. These findings suggest that cabozantinib and CBD combination therapy has therapeutic potential for HCC.

Studies have shown that CBD can bind to cannabinoid receptor 1 (CNR1) and CNR2 and modulate their downstream molecular pathways. Therefore, the researchers aimed to identify key downstream molecules involved in the synergistic apoptotic effects of CBD combined with cabozantinib. They first investigated whether expression of CNR1 and CNR2, the primary receptors coupled to CBD, influences these effects. To this end, the researchers established a CNR overexpression system in HepG2 cells, which exhibit low endogenous expression levels of CNR1 and CNR2 (Figure 1A). The results demonstrated that the synergistic effects observed after combined treatment with cabozantinib and CBD, including cell proliferation, were independent of CNR1 or CNR2 (Figure 1B, C). Next, the researchers performed flow cytometry (FACS) analysis to assess whether CNR1 and CNR2 expression modulates the apoptotic effects of combined treatment with cabozantinib and CBD. Notably, CNR1 and CNR2 overexpressing cells exhibited similar apoptotic cell populations, including both early and late apoptotic cells, compared with control cells treated with cabozantinib and CBD (Figure 1D). Furthermore, Western blot analysis confirmed that the expression levels of apoptotic proteins (such as cleaved PARP, cleaved caspase-9, cleaved caspase-8, and Bax) in control cells treated with cabozantinib and CBD were comparable to those in CNR1 and CNR2 overexpressing cells (Figure 1E). In summary, the synergistic apoptotic effect mediated by combined treatment with cabozantinib and CBD is independent of CNR1 or CNR2.

Figure 1. Synergistic effects of cabozantinib and CBD combined treatment are not associated with cannabinoid receptors. (Jeon Y, et al., 2023)