001) and PR (p = 0.002) (Table 2). Further statistical analysis revealed HBO1 protein level correlated positively with histology grade in ERα positive tumors (p = 0.016) rather than ERα negative tumors (Table 2). For benign breast tissues, low HBO1 immunoreactivity was observed and epithelial cells displayed a minimal

granular click here staining (Figure 1A). Moderately and poorly differentiated breast cancer tissues showed intense HBO1 staining (Figure 1B-C). To further study the relationship between HBO1 and ERα, we examined HBO1 expression level in several breast cancer cell lines by western blot, which showed that ERα positive breast cancer cell lines exhibited higher HBO1 protein than ERα negative breast cancer cell Selleck RG7420 lines (Figure 1D). Figure 1 Expression of HBO1 in human breast cancer. (A) Immunohistochemical A-1210477 clinical trial staining for HBO1 in benign breast epithelial tissues (magnification: A, 400×). (B) Moderately differentiated breast cancer tissues (brown staining) (magnification: B, 400×). (C) Poorly differentiated breast cancer tissues (brown staining) (magnification: C, 400×). (D) HBO1 protein level in several breast cancer cell lines based on the western blot results. Table 1 Clinical and pathological characteristics of patients characteristic value Tumor grade(n[%])   I 45 [40.2%] II/III 67 [59.8%] Ki67 status(n[%])   negative 50 [44.6%] positive 62 [55.4%] Estrogen

receptor α status(n[%])   negative 39 [34.8%] positive

73 [65.2%] Progesterone receptor status(n[%])   negative 60 [53.6%] positive 52 [46.4%] P53 status(n[%])   Negative 62 [55.4%] Positive 50 [44.6%] HBO1 status(n[%])   negative 48 [42.9%] positive 64 [57.1%] Histology Grade (n[%])   G1 32 [28.6%] G2/G3 80 [71.4%] Table 2 Expression of HBO1 in relation to the clinical and pathological characteristics of patients clinical feature total HBO1 expression P -value     negative positive   Tumor grade I 45 21 24 0.610 II/III 67 28 Florfenicol 39   Ki67 negative 50 23 27 0.550 positive 62 25 37   Estrogen receptor negative 39 26 13 < 0.001** positive 73 22 51   Progesterone receptor negative 60 34 26 0.002** positive 52 14 38   P53 negative 62 23 39 0.170 positive 50 25 25   Histology Grade G1 32 17 15 0.165 G2/G3 80 31 49   among ER positive tumors Histology Grade G1 25 12 13 0.016* G2/G3 48 10 38   among ER negative tumors Histology Grade G1 8 5 3 0.779 G2/G3 31 21 10   * P < 0.05 ** P < 0.01 E2 induces HBO1 expression in breast cancer cells In order to further investigate the relationship between ERα and HBO1, we treated breast cancer cells with 17β-estradiol (E2). Quantitative real-time PCR was used to determine the effect of E2 on the mRNA level of HBO1. With the dose of E2 increasing from 10-9 to 10-7 M, the mRNA level of HBO1 gradually increased and reached a plateau at 10-8 M in T47 D cells (Figure 2A). Hereby, 10-8 M of E2 was applied for all subsequent experiments.