PIWIL1 and cancer: As a cancer hallmark discovered in recent years, the immunosuppressive microenvironment surrounding the tumor cells was composed of a series of immune and non-immune components.30 Tumor cells tend to foster an immunosuppressive microenvironment to facilitate its progression and metastasis, in which several types of immune cells such as TAMs and MDSCs, play a crucial role.31 As an increase in the MDSCs population was observed, we further depicted the detailed profile of MDSCs in PIWIL1-overexpressing HCC.