SIRT6 and neoplasm: SIRT4 has been reported to function as a tumor suppressor in published studies, and reduced expression in OC was reported in a meta-analysis (Csibi et al., 2013).The mRNA expression of SIRT6 in 32 OC tissue samples was remarkably lower than that in paired normal ovarian tissues (Zhang et al., 2015), whereas there were higher SIRT7 mRNA levels in OC, although without statistical significant, which could have been due to the small sample sizes analyzed (Aljada et al., 2015).