However, other studies reported a decrease in the expression of TUG1 by metformin in vascular wall cells (You et al., 2020), a decrease in the expression of HOTAIR by metformin in MDA-MB-231 breast cancer cells (Golshan et al., 2021), and a decrease in the expression of MALAT1 by metformin in cervical cancer cells (Xia et al., 2018). This evidence concerns the gene TUG1 and breast cancer.