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Figure 6 | Breast Cancer Research

Figure 6

From: Buthionine sulfoximine sensitizes antihormone-resistant human breast cancer cells to estrogen-induced apoptosis

Figure 6

Buthionine sulfoximine (BSO) inhibits the growth of MCF-7:2A tumors in vivo. Athymic nude mice (4 to 5 weeks old, n = 20) were injected with MCF-7:2A breast cancer cells and after 20 days when tumors had reached a mean cross-sectional area of 0.3 cm2, animals were randomized into 4 groups and were treated with placebo (saline), 17β-estradiol (E2), BSO, or BSO plus E2 for 7 days as described in Materials and methods. BSO (4 mmol/kg weight) was diluted in saline and was injected intraperitoneally daily. (a) Tumor size was measured everyday and cross-sectional area was calculated by multiplying the length (l) by the width (w) by π and dividing the product by 4 (lwπ/4). Data is shown as mean ± standard error of the mean (SEM). *, p < 0.05, control group compared with the E2 group; †, p < 0.002 control group compared with BSO group; § p < 0.001 control group compared with BSO + E2 group. (b) Microscopy of hematoxylin and eosin (H&E)-stained histological sections of MCF-7:2A tumors treated with placebo, E2, BSO, or BSO plus E2. (c) Immunohistochemical analysis of the proliferation marker Ki-67 in MCF-7:2A tumors treated with placebo, E2, BSO, or BSO plus E2. (d) Paraffin-embedded tumor sections of mice treated with E2, BSO, or BSO plus E2 were immunostained for proteolytically cleaved poly(ADP-ribose) polymerase (PARP), which exists only when cells undergo apoptosis. Three to four tumors per treatment group were analyzed.

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