PYGO2 and breast cancer: Previous studies have shown that miR‐516a‐3p expression is down‐regulated and has a similar tumour suppressor role in gastric cancer and ovarian cancer.14, 15 With respect to Pygo2, it has been confirmed as a tumour promoter in breast cancer,22 colorectal cancer,33 ovarian cancer,34 advanced prostate cancer35 and glioma.36 Zhou SY et al37 reported that Pygo2 was overexpressed in human lung cancer tissue samples and cell lines and that the knockdown of Pygo2 suppressed the growth of lung cancer in vitro and in vivo.