Fig. 2: Hypoxia-induced LOX hyperactivates ITGA5/FN1/FAK/Src axis in TNBCs.

a Expression of a HIF-1α direct target gene, carbonic anhydrase 9 (CA9) in sensitive (n = 3) vs. resistant (n = 3) tumors at mRNA (left) and protein (right) levels, demonstrating predominantly membranous and mild cytoplasmic staining. b Genes upregulated upon hypoxia are enriched in patients with high DoxoR-GS score from GSE58812 (n = 106). c, d. % growth inhibition upon doxorubicin treatment of MDA-MB-231 (c) (n = 3) and MDA-MB-157 (d) (n = 4) cells grown under normoxic vs. hypoxic conditions. e Expression of LOX in sensitive (n = 12) vs. resistant (n = 9) tumors at mRNA (left) and protein (right) levels, demonstrating strong cytoplasmic and weak nuclear staining. f, g Representative images of Picrosirius red staining (f) and its quantification (g) (n = 6). h Heatmap summarizing the Pearson’s correlation coefficients between HIF1A and LOX, ITGA5 or FN1 and between LOX and ITGA5 or FN1 in breast cancer patients. An intense red color shows a stronger positive correlation. i qRT-PCR analysis of LOX, ITGA5, and FN1 under hypoxia (n = 3). j Western blot analyses of HIF-1α, LOX and integrin signaling members under hypoxia. k Relative LOX activity in MDA-MB-231 cells under hypoxia. BAPN was used as a negative control (n = 3). l qRT-PCR analysis of LOX, ITGA5, and FN1 after transfection with siAllStar or siLOX (n = 3). m, n Western blot analyses in MDA-MB-231 cells transfected with siAllStar or siLOX (m) and after shLOX induction with doxycycline (n). o Kaplan–Meier survival curve representing the percentage RFS in chemotherapy-treated basal breast cancer patients (n = 132) separated based on low vs. high (median) LOX mRNA. p IHC images of TNBC patient tissues with low and high LOX protein expression. q Kaplan–Meier survival curve representing DFS in chemotherapy-treated TNBC patients (n = 77) separated from median based on LOX protein expression. Data represents mean ± SD. Two-sided Student’s t-test was used to calculate statistical difference between two groups. Significance for survival analyses was calculated by log-rank (Mantel-Cox) test. NES Normalized enrichment score, HR hazard ratio. Scale bar = 100 µm for a, e, and p, and 400 µm for f. Source data are provided as a Source data file.