Erratum to: Pathways mediating the effects of cannabidiol on the reduction of breast cancer cell proliferation, invasion, and metastasis

Erratum to: Breast Cancer Res Treat (2011) 129:37–47 DOI 10.1007/s10549-010-1177-4

The original publication of the article includes figures of lower resolution. The author would like to correct this with the publication of higher resolution figures that are reproduced below.

Fig. 1

CBD up-regulates ERK phosphorylation and Id-2 expression. (A) Proteins from MDA-MB231 cells treated with 1.5 μM CBD (as previously described [21]) for 1 or 2 days were extracted and analyzed for Id-1, total ERK, pERK, or p38 by Western blot analysis. (B) Proteins from MDA-MB231 cells treated with CBD for 3 days were extracted and analyzed for Id-1, Id-2, or NFkappaB by Western blot analysis

Fig. 2

ERK partly mediates the inhibitory activity of CBD on cell growth and invasion. MDA-MB231 cells were treated for 3 days with vehicle (Control) or 1.5 μM CBD in the presence and absence of 0.1–0.5 μM U0126. Cell proliferation (A) and invasion (B) were measured using the MTT and Boyden chamber assays, respectively. Data are presented as relative proliferation or invasiveness of the cells, where the respective controls are set as 100%. (C) Proteins from MDA-MB231 cells treated with vehicle (control) or 1.5 μM of CBD for 3 days in the absence or presence of U0126 were extracted and analyzed for Id-1 by Western blot analysis. (*) indicates statistically significant difference from control (P < 0.05). (#) indicates statistically significant difference from CBD (P < 0.05)

Fig. 3

Production of ROS represents another factor involved in the inhibitory activity of CBD. MDA-MB231 cells were treated for 3 days with vehicle (Control) or 1.5 μM CBD in the presence and absence of 20 μM TOC. Cell proliferation (A) and invasion (B) were measured using the MTT and Boyden chamber assay, respectively. (C) Proteins from cells treated with vehicle (control) or 1.5 μM of CBD for 3 days in the absence or presence of TOC were extracted and analyzed for Id-1 by Western blot analysis. (D) The production of ROS was measured using 2′-7′ Dichloro-dihydrofluorescein (Sigma-Aldrich). (*) indicates statistically significant differences from control (P < 0.05)

Fig. 4

CBD inhibits the expression of Id-1 and corresponding breast cancer proliferation and invasion in mouse 4T1 cells. (A) 4T1 cells were treated for 3 days with 1.5 μM CBD, proteins were extracted and analyzed for Id-1 expression. (B) 4T1 cells were collected and cell cycle analyzed using a desktop FACS Calibur with Cell Quest Pro software (BD Bioscience, CA). The distribution of cells in different cell cycle stages was determined according to their DNA content. (C) Invasion assays were carried out using the Boyden chamber assay. (*) indicates statistically significant differences from control (P < 0.05)

Fig. 5

CBD reduces primary tumor growth and metastasis of 4T1 cancer cells in an orthotopic mouse model. Primary tumors and subsequent secondary tumors (metastases) were generated in BALB/c mice by subcutaneous injection of 1 × 10⁵ 4T1 cells under the fourth major nipple. Treatment with CBD was initiated upon detection of the first palpable tumor (approximately 7 days). (A) The primary tumor volume was calculated by measuring the perpendicular largest diameters of the tumor with a caliper. (B) The weight of the tumors was also measured. (C) The visible lung metastases were measured using a dissecting microscope. (D) The average volume per metastatic foci was calculated as described in the methods. (*) indicates statistically significant differences from vehicle (P < 0.05)

Fig. 6

CBD reduces the number of metastatic foci in the syngeneic model of tail vein injection. Lung metastases were generated in BALB/c mice after tail vein injection of 5 × 10⁵ 4T1 cells. One day after the injection, the tumor-bearing mice were injected i.p. once a day with vehicle or 1 mg/kg CBD for 15 days. Visible lung metastases were counted and measured by using a dissecting microscope (A). Lung metastases measured included those (B) <1 mm, (C) 1–2 mm, and (D) >2 mm