Cal 51

TNBC cell line CAL-51 was grown in DMEM (Gibco) supplemented with 20% fetal bovine serum (FBS, Serana), 1% penicillin-streptomycin (P/S, Gibco) and 2mM L-glutamine (Gibco). TNBC cell line CAL-120 was grown in DMEM supplemented with 10% FBS, 1% P/S and 2 mM L-glutamine. TNBC cell line HCC1806, lung cancer cell lines A549 and H2122, colon cancer cell lines DLD-1 and RKO were grown in RPMI (Gibco) supplemented with 10% FBS, 1% P/S and 2 mM L-glutamine. TNBC cell line SUM159 was grown in DMEM/F12 (Gibco) supplemented with 10% FBS, 1% P/S, 5 μg/ml insulin (Sigma-Aldrich) and 1μg/ml hydrocortisone (Sigma-Aldrich).
HCC1806, A549, RKO, H2122 and DLD-1 were purchased from ATCC. SUM159 was a gift from Metello Innocenti (NKI, Amsterdam). CAL-51 and CAL-120 were obtained from DSMZ. All cell lines were regularly tested for mycoplasma contamination using a PCR assay and STR profiled (Eurofins).

Normal breast epithelial cell line MCF-10A, breast cancer cell lines MDA-MB-231, MCF-7, SK-BR3, T47D, and Cal51 were obtained from ATCC (American Type Culture Collection, Manassas, USA). MCF-10A was cultured in MCF-10A cell-specific medium (Procell, China). MCF-7, T47D and MDA-MB-231 were cultured in DMEM (Gibco, USA), while Cal51 in 1640 (Gibco, USA). All medium included 10% fetal bovine serum (FBS, NEWZERUM, Australia) and 1% penicillin/streptomycin (Gibco, USA). The cells were kept at 37 °C in a humidified 5% CO₂ atmosphere cell incubator.
The CMTM7 and TCF3 plasmids and their corresponding vectors, as well as miR-182-5p mimic, inhibitor, and the siRNA kits of CMTM7, were obtained from RiboBio (Guangzhou, China). The miRNAs and siRNAs oligonucleotides are listed in Additional file 1: Table S1. The CMTM7 3′UTR region, the miR-182-5p promoter region, and their mutants were cloned into the pGL4.17-basic vector (Promega, USA). The transfection was conducted utilizing Lipofectamine 3000 (Invitrogen, USA) in accordance with the manufacturer’s recommendations. Lentiviruses (RiboBio, China) were utilized to infect MCF-7 cells and generate stable CMTM7 overexpressed cells by the manufacturer’s protocol.

Cell lines maintained in DMEM supplemented with 10% FBS were available from ATCC (HCC-1806, MDA-MB-231) and Creative Bioarray (CAL-51, SUM-159pt). Cell lines were authenticated by STR analyses and mycoplasma tested (MycoAlert^TM, Lonza) at regular intervals. Cells were maintained in a humidified incubator at 5% CO₂ and 37°C and hypoxic exposure was at either 1% or 0.5% (BakerRuskinn, InvivO₂). Normoxia was defined as 21% O₂ 5% CO₂. Acidosis media was prepared as previously [16] (link). Spheroid aggregation was initiated with 10,000 cells in ultra-low–adherent round-bottom 96-well plates followed by centrifugation at 2000 × g. Clonogenic assays were performed as previously [16] (link). To knockdown SLC4A4 or SLC4A5 in HCC-1806, CAL-51, and MDA-MB-231, shRNA lentivirus was purchased from Sigma-Aldrich (Supplementary Table 2). Cells were grown under Puromycin (Gibco) selection (HCC-1806 and MDA-MB-231 2 μg/mL; CAL-51, 10 μg/mL) to select shRNA expressing cells. Experiments were optimised and normalised by cell number at the end of experiments.