Fig. 2: ASS1 expression is inversely correlated with PHGDH protein expression in TNBC.

A Immunoblotting (IB) of PHGDH and ASS1 protein in MCF-10A and 11 breast cancer cell lines, with GAPDH serving as a loading control. B RT-qPCR analysis of PHGDH mRNA levels in 11 breast cancer cell lines relative to the MCF-10A cell line. GAPDH was used as an internal control. Three independent experiments were performed, and the data are shown as the mean ± SD with p-values based on one-way ANOVA (n = 3, *p < 0.05, **p < 0.01, ***p < 0.001, n.s., not significant). C, D Immunoblotting assays assessing the expression levels of PHGDH in MDA-MB-468 cells with ASS1 knockout (C) or ASS1 overexpression (D). E, F Immunoblotting assays assessing the expression levels of PHGDH in Hs578T cells with ASS1 knockdown (E) or overexpression (F). G Analysis of ASS1 and PHGDH protein levels in 91 tissues from recurrent TNBC patients and 70 tissues from nonrecurrent TNBC patients by IHC assays. The images shown are from three representative experiments. Scale bars: 200 μm. H-I ASS1 (H) and PHGDH (I) protein expression levels in recurrent (n = 91) and no recurrence (n = 70) human TNBC patients. Data are shown as mean ± SD with p-values based on unpaired T-test, **p < 0.01. J Correlation analysis of ASS1 and PHGDH protein expression in human recurrent triple-negative breast cancer tissues (n = 91) revealed a significant correlation (Pearson’s correlation, r = −0.799; p < 0.01).