Cannabinoids attenuate cancer pain and proliferation in a mouse model

Abstract

We investigated the effects of cannabinoid receptor agonists on (1) oral cancer cell viability in vitro and (2) oral cancer pain and tumor growth in a mouse cancer model. We utilized immunohistochemistry and Western blot to show that human oral cancer cells express CBr1 and CBr2. When treated with WIN55,212-2 (non-selective), ACEA (CBr1-selective) or AM1241 (CBr2-selective) agonists in vitro, oral cancer cell proliferation was significantly attenuated in a dose-dependent manner. In vivo, systemic administration (0.013M) of WIN55,212-2, ACEA, or AM1241 significantly attenuated cancer-induced mechanical allodynia. Tumor growth was also significantly attenuated with systemic AM1241 administration. Our findings suggest a direct role for cannabinoid mechanisms in oral cancer pain and proliferation. The systemic administration of cannabinoid receptor agonists may have important therapeutic implications wherein cannabinoid receptor agonists may reduce morbidity and mortality of oral cancer.

Figure 1

CBr1 and CBr2 are present in human head and neck cancer cells (a). Immunofluorescence of human squamous cell carcinoma (SCC) cells revealed homogeneous cytoplasmic and membrane staining for CBr1 and CBr2. Representative bright field (left panel) and corresponding immunofluorescence images for CBr1 (green, middle) and CBr2 (red, right panel). Scale bar=20μm. Western blot analysis of cannabinoid receptor expression in NOK, HCS3 and SCC9 cells revealed that all three cell lines express CBr1 and CBr2 (b). The expression of Actin was also demonstrated as control. Image analysis of the results of western blot indicates that the cancer cell lines express a higher level of cannabinoid receptors compared to NOK.

Figure 1

CBr1 and CBr2 are present in human head and neck cancer cells (a). Immunofluorescence of human squamous cell carcinoma (SCC) cells revealed homogeneous cytoplasmic and membrane staining for CBr1 and CBr2. Representative bright field (left panel) and corresponding immunofluorescence images for CBr1 (green, middle) and CBr2 (red, right panel). Scale bar=20μm. Western blot analysis of cannabinoid receptor expression in NOK, HCS3 and SCC9 cells revealed that all three cell lines express CBr1 and CBr2 (b). The expression of Actin was also demonstrated as control. Image analysis of the results of western blot indicates that the cancer cell lines express a higher level of cannabinoid receptors compared to NOK.

Figure 2

Cannabinoid agonists decrease oral cancer cell viability in vitro. Mean percent change in cell viability relative to control in oral cancer cells treated with WIN55,212-2(a), ACEA (b), or AM1241(c), as measured by MTS assay. WIN55,212-2, ACEA and AM1241 caused a dose-dependant decrease in HSC3 viability (n=7/group, * p<0.05 ANOVA).

Figure 2

Cannabinoid agonists decrease oral cancer cell viability in vitro. Mean percent change in cell viability relative to control in oral cancer cells treated with WIN55,212-2(a), ACEA (b), or AM1241(c), as measured by MTS assay. WIN55,212-2, ACEA and AM1241 caused a dose-dependant decrease in HSC3 viability (n=7/group, * p<0.05 ANOVA).

Figure 2

Cannabinoid agonists decrease oral cancer cell viability in vitro. Mean percent change in cell viability relative to control in oral cancer cells treated with WIN55,212-2(a), ACEA (b), or AM1241(c), as measured by MTS assay. WIN55,212-2, ACEA and AM1241 caused a dose-dependant decrease in HSC3 viability (n=7/group, * p<0.05 ANOVA).

Figure 3

Cannabinoid agonists attenuate oral carcinoma-induced pain. WIN55,212-2, significantly increased mean paw withdrawal threshold on days 7, 15 and 18 relative to control. ACEA, showed a significant increase in paw withdrawal threshold on day 18. AM1241, showed significantly increased mean paw withdrawal threshold on day 15 and 18. (n=6/group, *p<0.05, ** p<0.01 ANOVA).

Figure 4

Cannabinoid agonists attenuate oral cancer growth. WIN55,212-2, significantly reduced tumor volume compared to control on day 9 (ANOVA). AM1241, significantly reduced tumor volume compared to control on days 7, 9, 11 and 18. (n=6/group, *p<0.05, **p<0.01, ***p<0.001 ANOVA). There was a trend for ACEA to reduce tumor volume.