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. 2022 Mar 2;13(3):199. doi: 10.1038/s41419-022-04647-6

Fig. 1. Extracellular ATP promotes breast cancer chemoresistance via HIF-1α.

Fig. 1

A CCK-8 assay measured by absorbance OD450 illustrated that ATP enhanced the chemotherapy resistance of cisplatin, doxorubicin, paclitaxel, and gemcitabine in MDA-MB-231 (upper) and MCF-7 cells (lower). B Western blotting showed expressions of HIF-1α in MCF-10A, MCF-7, and MDA-MB-231 cell lines. C Western blotting demonstrated expression of HIF-1α was knocked down in MDA-MB-231 and MCF-7 cells. D MDA-MB-231 and MCF-7 cells were transfected with NC-siRNA or HIF-1α-siRNA for 48 h, followed by cisplatin/doxorubicin treatment alone or in combination with ATP for a further 4 days. CCK-8 assay proved that ATP-promoted cisplatin/doxorubicin resistance was attenuated by HIF-1α-siRNA. E, F MDA-MB-231 and MCF-7 cells were transfected with NC-siRNA or HIF-1α-siRNA for 48 h, followed by cisplatin treatment alone or in combination with ATP for a further 2 days. Cell counting via trypan blue dye exclusion assay (E) and annexin V/PI dual staining assays (F) proved that ATP-promoted cisplatin resistance was attenuated by HIF-1α-siRNA. G MDA-MB-231 and MCF-7 cells were transfected with NC-siRNA or HIF-1α-siRNA or treated with cisplatin or ATP twice a week. Clonogenic assay (3 weeks) in 6-well plate showed that HIF-1α-siRNA attenuated ATP-enhanced cisplatin resistance of MDA-MB-231 and MCF-7 cells. Data are representative of at least three independent experiments. Error bars represent means ± SD from triplicate experiments. *p < 0.05; **p < 0.01; ***p < 0.001; ns, not significant.