Extended Data Figure 10: Role of XBP1 in luminal breast cancer.
From: XBP1 promotes triple-negative breast cancer by controlling the HIF1α pathway
a, XBP1 splicing is induced by hypoxia and glucose deprivation in luminal cancer cells. RT–PCR of XBP1 splicing in T47D and SKBR3 cells under different treatments for 24 h. XBP1u, unspliced XBP1; XBP1s, spliced XBP1. Hypoxia: 0.1% O2. b, Left panel: quantification of soft agar colony formation in untreated and control shRNA or XBP1 shRNA infected breast cancer cells. Experiments were performed in triplicate and data are shown as mean ± s.d. **P < 0.01. Right panel: effect of XBP1 depletion on soft agar colony formation in luminal versus basal cell lines. Percentages of soft agar colonies formed from cells infected with XBP1 shRNA lentivirus relative to the same cell line infected with shCtrl lentivirus (set as 100%) are presented. 5 cell lines in each group (as in left panel) and data are shown as mean ± s.d. c, Tumour growth (mean ± s.d.) of ZR-75-1 cells treated with control shRNA (n = 4), paclitaxel (20 mg kg−1) + control shRNA (n = 4), XBP1 shRNA (n = 4) or paclitaxel + XBP1 shRNA (n = 3) in nude mice. TX, treatment with shRNA or paclitaxel + shRNA. Asterisk denotes shXBP1-treated tumours significantly different from shCtrl-treated tumours; P < 0.05. d, Number of mammospheres per 1,000 cells generated by control shRNA or XBP1 shRNA-encoding lentivirus infected T47D or SKBR3 breast cancer cell lines cultured under normoxia or hypoxia and glucose deprivation conditions (treated). Experiments were performed in triplicate and data are shown as mean ± s.d. e, Venn diagram showing the overlap between XBP1 targets in MDA-MB-231, Hs578T cells and T47D cells cultured under hypoxia and glucose deprivation conditions. f, XBP1s overexpression is not capable of converting a luminal phenotype to basal phenotype. RT–PCR analysis of luminal marker (CK8, CK18, CK19 and E-cadherin) and basal marker (CK5, CK14, p63, fibronectin and vimentin) expression in luminal breast cancer cells (MCF7 or T47D) infected with lentivirus encoding empty vector or XBP1s. Data are shown as mean ± s.d. of technical triplicates.
