β-D-glucan inhibits endocrine-resistant breast cancer cell proliferation and alters gene expression

Abstract

Endocrine therapies have been successfully used for breast cancer patients with estrogen receptor α (ERα) positive tumors, but ∼40% of patients relapse due to endocrine resistance. β-glucans are components of plant cell walls that have immunomodulatory and anticancer activity. The objective of this study was to examine the activity of β-D-glucan, purified from barley, in endocrine-sensitive MCF-7 versus endocrine-resistant LCC9 and LY2 breast cancer cells. β-D-glucan dissolved in DMSO but not water inhibited MCF-7 cell proliferation in a concentration-dependent manner as measured by BrdU incorporation with an IC50 of ∼164±12 μg/ml. β-D-glucan dissolved in DMSO inhibited tamoxifen/endocrine-resistant LCC9 and LY2 cell proliferation with IC50 values of 4.6±0.3 and 24.2±1.4 μg/ml, respectively. MCF-10A normal breast epithelial cells showed a higher IC50 ∼464 μg/ml and the proliferation of MDA-MB-231 triple negative breast cancer cells was not inhibited by β-D-glucan. Concentration-dependent increases in the BAX/BCL2 ratio and cell death with β-D-glucan were observed in MCF-7 and LCC9 cells. PCR array analysis revealed changes in gene expression in response to 24-h treatment with 10 or 50 μg/ml β-D-glucan that were different between MCF-7 and LCC9 cells as well as differences in basal gene expression between the two cell lines. Select results were confirmed by quantitative real-time PCR demonstrating that β-D-glucan increased RASSF1 expression in MCF-7 cells and IGFBP3, CTNNB1 and ERβ transcript expression in LCC9 cells. Our data indicate that β-D-glucan regulates breast cancer-relevant gene expression and may be useful for inhibiting endocrine-resistant breast cancer cell proliferation.

Regulation of Gene Expression by β-Glucans

“…We examined the effect of two concentrations of β-Dglucan on the expression of a set of genes implicated in breast cancer in MCF-7 and LCC9 cells using a PCR array. We reported that β-D-glucan inhibited the expression of cell proliferation and differentiation markers in MCF-7 cells, e.g., CDKN1C, CTNNB1, ERBB2, MUC1 and RARB (Jafaar et al, 2014). These changes in gene expression correspond to the observation that β-D-glucan dissolved in DMSO, but not water, inhibits MCF-7 cell proliferation (Jafaar et al, 2014).…”

“…(1->6) D glucan 100 µg mL glucan; mice were fed beta glucan daily for 12 days β-D-glucan increased the expression of 9 genes in MCF-7 human breast cancer cells and 5 genes in LCC9 breast cancer cells (Jafaar et al, 2014). These genes are summarized in Table 1.…”

“…A water-soluble β-glucan extract from the mycelia of Poriacocos inhibited the viability (MTT assay) of MCF-7 human breast cancer cells with an IC 50 of 400 µg mL −1 and decreased cyclin D1 and cyclin E protein expression (Zhang et al, 2006). We reported that a purified preparation of β-D-glucan (from barley) dissolved in DMSO -but not water-inhibited the growth of estrogen receptor α (ERα)+ MCF-7 cells with an IC 50 of ~164±12 µg mL −1 compared to normal breast epithelial (ERα-) MCF-10A cells, IC 50~4 64 µg mL −1 (Jafaar et al, 2014). β-glucan inhibited the estradiol (E 2 )-independent, tamoxifen (TAM) and fulvestrant-resistant, ERα + LCC9 and LY2 cells (derived from MCF-7 cells) with IC 50 values of 4.6±0.3 and 24.2±1.4 µg mL −1 , respectively (Jafaar et al, 2014).…”

“…We reported that a purified preparation of β-D-glucan (from barley) dissolved in DMSO -but not water-inhibited the growth of estrogen receptor α (ERα)+ MCF-7 cells with an IC 50 of ~164±12 µg mL −1 compared to normal breast epithelial (ERα-) MCF-10A cells, IC 50~4 64 µg mL −1 (Jafaar et al, 2014). β-glucan inhibited the estradiol (E 2 )-independent, tamoxifen (TAM) and fulvestrant-resistant, ERα + LCC9 and LY2 cells (derived from MCF-7 cells) with IC 50 values of 4.6±0.3 and 24.2±1.4 µg mL −1 , respectively (Jafaar et al, 2014). In contrast, the "triple negative/basal-like" MDA-MB-231 breast cancer cells were not growth inhibited by β-glucan (Jafaar et al, 2014).…”

“…β-glucan inhibited the estradiol (E 2 )-independent, tamoxifen (TAM) and fulvestrant-resistant, ERα + LCC9 and LY2 cells (derived from MCF-7 cells) with IC 50 values of 4.6±0.3 and 24.2±1.4 µg mL −1 , respectively (Jafaar et al, 2014). In contrast, the "triple negative/basal-like" MDA-MB-231 breast cancer cells were not growth inhibited by β-glucan (Jafaar et al, 2014). Conversely, aqueous-soluble β-glucans reportedly had no direct cytotoxic effects on a panel of common cancer cell lines including blastoma, carcinoma and sarcoma cells (Chan et al, 2009).…”