Fig 2: Expression of CD98hc in normal and TNBC tumoral tissue. A Immunohistochemical stainings of CD98hc showing tumor tissue scored as high (+++), intermediate (++) and low (+), and normal tissue with negative (-) staining. Magnification: 40X. B Immunohistochemical staining of CD98hc in a sample of a patient, showing staining of CD98hc only in tumor tissue and not in normal tissue. Magnification: 20 X. C Box plot showing SLC3A2 gene expression levels in normal and tumor tissue of breast cancer patients. Data were obtained from the TNMplot database. D Box plot showing SLC3A2 gene expression levels in different breast cancer subtypes from patients with breast cancer. The data were obtained using the Xena online tool

Fig 3: SCRIB targets SLC3A2 in ER+ breast cancer cells.a Detection of endogenous SCRIB-SLC3A2 interaction in MCF-7 cells. b Co-localization of SCRIB and SLC3A2 in MCF-7 cells. Scale bar, 10 µm. c Immunoprecipitants using the anti-SLC7A5 antibody in MCF-7 cells. d Immunoprecipitation of SLC7A5 in SLC3A2-KD cells. e Immunoprecipitation of Flag-LLGL2 using anti-Flag antibody in SLC3A2-KD MCF-7 cells. f Cartoon representation of wild-type SCRIB and SCRIB mutants. g Immunoprecipitation of SCRIB in HEK293T transfected with indicated vectors. h Immunoprecipitation of wild-type and mutant SCRIB in MCF-7 cells.

Fig 4: SLC3A2 promotes cell proliferation in ER+ breast cancer cells.a Kaplan–Meier plots of ER+/PR+ and ER−/PR− BC patients’ survival. b Overexpression of SLC3A2 in MCF-7 cells. c Cell viability assay of SLC3A2-OE MCF-7 cells. d Knockdown of SLC3A2 in MCF-7 cells. e Cell viability assay of SLC3A2-KD MCF-7 cells. f 2D growth of SLC3A2-KD MCF-7 cells. g Tumor growth of SLC3A2-KD MCF-7 cells in NSG mice. h Total protein levels of SLC7A5 in SLC3A2-KD MCF-7 cells. i Total protein levels of SLC3A2 in SLC7A5-KD MCF-7 cells. j Heatmap of metabolites in SLC3A2-KD MCF-7 cells. k Venn diagram representation of the number of intracellular metabolites downregulated by SLC3A2-KD in MCF-7 and T47D cells (left) and downregulated in both SLC3A2-KD and SCRIB-KD cells (right). l List of metabolites downregulated by SLC3A2-KD and SCRIB-KD. Data c, e, f, and g are shown as mean ± s.e.m.; c, and e; n = 9 from three biological replicates performed in triplicate, f; n = 3, g; n = 5 for control cells and n = 4 for SLC3A2-KD cells. Statistical analysis was conducted by t-test (c, e), and two-way ANOVA followed by Tukey’s posttest (f) or Sidak’s posttest (g).

Fig 5: SCRIB regulates intracellular localization of SLC3A2 in ER+ breast cancer cells.a Immunohistological images of SLC3A2 in ER+ and ER− breast cancer. The numbers of specimens were indicated in each image. b Total protein levels of SLC3A2 and SLC7A5 in breast cancer cell lines. Immunoblot images (left) and the relative ratio of signal intensities are shown (right). c Cellular surface protein levels of SLC3A2 and SLC7A5 in breast cancer cell lines. d Normalized intensity of surface protein levels of SLC7A5 and SLC3A2 in ER+ or ER− breast cancer cells. e Immunoprecipitation of HA-SCRIB using anti-HA antibody in HEK293T cells. f Total protein levels of SLC7A11 in breast cancer cell lines. Immunoblot image (left) and the relative ratio of signal intensities are shown (right).