BMI1

BMI1 Full Name

BMI1 proto-oncogene, polycomb ring finger

BMI1 Introduction

BMI1, located on the short arm of human chromosome 10 (10p12.2), encodes a highly conserved RING finger domain-containing transcriptional repressor and serves as a core component of Polycomb repressive complex 1 (PRC1). With a molecular weight of approximately 41 kDa, BMI1 primarily functions as an E3 ubiquitin ligase through its N-terminal RING domain, catalyzing monoubiquitination of histone H2A at lysine 119 (H2AK119ub1) to mediate transcriptional silencing of target genes. BMI1 plays a critical role in embryonic development, somatic stem cell self-renewal, and the regulation of cellular senescence. While its expression remains relatively low in most normal tissues, BMI1 is frequently upregulated in a wide range of malignancies.

Figure 1. Gene and protein structure of BMI1. (Source: Sahasrabuddhe AA. 2016)

As an epigenetic regulator, BMI1 modulates gene expression networks through both PRC1-dependent and independent mechanisms. A central function is the repression of the INK4A/ARF locus thereby alleviating constraints imposed by the Rb and p53 pathways and promoting cellular immortalization. In stem cell biology, BMI1 helps sustain cancer stem cell (CSC) self-renewal and stemness by regulating key signaling pathways such as Notch, Wnt/β-catenin, and PTEN/PI3K/Akt, thereby driving tumor initiation, recurrence, and chemotherapy resistance. Additionally, BMI1 is involved in DNA damage repair, evasion of cellular senescence, and the maintenance of mitochondrial function during neural development. Dysregulation of BMI1 can lead to disrupted cell fate determination and genomic instability.

BMI1 acts as an oncogenic driver in numerous cancers. Its overexpression is strongly associated with aggressive phenotypes, poor prognosis, and therapy resistance in breast cancer, colorectal cancer, glioblastoma, lung cancer, hepatocellular carcinoma, and leukemia, among others. Clinical studies indicate that BMI1 is not only a potential diagnostic biomarker but also a promising therapeutic target, with small-molecule inhibitors targeting its E3 ligase activity and protein degradation strategies currently under development.

Alternate Names for BMI1

BMI1; BMI1 proto-oncogene, polycomb ring finger; PCGF4; RNF51; FLVI2/BMI1; polycomb complex protein BMI-1; flvi-2/bmi-1; ring finger protein 51; polycomb group protein Bmi1; BMI1 polycomb ring finger oncogene

• 1. Yang D, et al. BMI1 in the heart: Novel functions beyond tumorigenesis. EBioMedicine. 2021 Jan;63:103193.
  2. Sahasrabuddhe AA. BMI1: A Biomarker of Hematologic Malignancies. Biomark Cancer. 2016 May 5;8:65-75.