Fig. 5

Effect of metformin on PTPRD-inactivated cancer cells. a Western blotting after treatment with metformin. Cancer cells were collected 15 min after treatment with metformin. b CXCL8 mRNA expression was assessed by RT−/qRT-PCR after treatment with metformin for 72 h. c The amount of secreted CXCL8 was assessed by ELISA after treatment with metformin for 72 h. d In vitro tube formation assay after treatment with metformin. Cancer cells were treated with metformin for 72 h and the media were changed to HUVEC media. After 24 h, HUVECs were incubated with these conditioned media for 6–10 h. e Cell viability was assessed by MTS assay 1, 3, and 5 days after 5 mM metformin treatment. These data are representative of three independent experiments. *p < 0.05; **p < 0.01; ***p < 0.001 by unpaired Student’s t-test. Scale bar = 200 μm