Cbx7, or Chromobox protein homolog 7, is a member of the Chromobox protein family and participates in the formation of the polycomb repressive complex 1(PRC1). It often acts as an epigenetic regulator to regulate gene expression in cells and is involved in various biological processes, such as the cell cycle, immune response, and DNA repair [1].

In cardiomyocytes, Cbx7 overexpression reduces neonatal cardiomyocyte proliferation and promotes multinucleation, while genetic inactivation of Cbx7 increases cardiomyocyte proliferation and promotes cardiac regeneration in neonatal and adult injured hearts. Mechanistically, Cbx7 interacts with TARDBP and positively regulates its downstream target, RBM38 [2]. In basal-like breast cancer, Cbx7 is down-regulated, and it suppresses cancer growth and metastasis through the Twist1/EphA2 pathway [3]. In urinary bladder cancer, down-regulation of Cbx7 due to promoter hypermethylation is correlated with poor prognosis, and its ectopic expression suppresses cancer cell proliferation, migration, invasion, and cancer stemness [4]. In meningioma, Cbx7 expression decreases with malignancy grade, and its restoration induces cell cycle arrest and inhibits cell proliferation by reprogramming metabolic flux [5]. In ovarian cancer, adipose-derived exosomal miR-421 targets Cbx7 and promotes metastatic potential [6]. In liver regeneration, silencing Cbx7 promotes hepatocyte proliferation, increases the liver/body weight ratio, and enhances the Ki67-positive cell count after hepatectomy [7].

In conclusion, Cbx7 plays crucial roles in various biological processes and disease conditions. Its functions in cell cycle regulation, cancer progression, and tissue regeneration are well-demonstrated through in vivo studies using gene knockout or conditional knockout mouse models. These models have provided valuable insights into the role of Cbx7 in specific disease areas such as cancer, cardiac and liver diseases, highlighting its potential as a therapeutic target.