Fig. 6
E2-induced MCF-7 breast cancer cell proliferation is blocked by 2′,3′,4′-THC. A MCF-7 cells transfected with ERE-TK-Luc were treated with 5 μM 2′,3′,4′-THC and 10 nM E2 alone or in combination for 24 h and then luciferase activity was measured. B Growth curve in MCF-7 breast cancer cells was determined with a Coulter counter after the cells were treated with increasing concentrations of 2′,3′,4′-THC without or with 1 nM E2 for 7 days. C The percentage of S phase cells was determined by flow cytometry after MCF-7 cells were treated with increasing amounts of 2′,3′,4′-THC without or with 0.1 nM E2 for 24 h. D Percentage of S phase cells in the cells treated with increasing concentrations of 2′,3′,4′-THC in the presence of 0.1 nM E2 or 1 nM estrone, estriol, or equilin for 24 h. E Percentages of S and G1 phase cells in the cells treated with increasing amount of tamoxifen (Tam) or 2′,3′,4′-THC in the presence of 0.1 nM E2 for 24 h were determined by flow cytometry. The error bars are means ± SE. The differences among various treatments were analyzed with two-way ANOVA followed by Sidak’s multiple comparisons post hoc test. The asterisks over the bars indicate the significant difference between E2 alone and E2 in combination with increasing amounts of 2′,3′,4′-THC