What does SMARCB1 encode that is relevant in cancer development?

SMARCB1 encodes a protein known as INI1 (also referred to as BAF47), which is a key component of the SWI/SNF chromatin remodeling complex. This complex plays a vital role in regulating gene expression by modifying chromatin structure, thus influencing DNA accessibility and transcription.

Mutations or deletions in the SMARCB1 gene are linked to various cancers, including atypical teratoid rhabdoid tumors (ATRT) and other malignant tumors, particularly in pediatric populations. The loss of INI1 function can lead to uncontrolled cellular proliferation and a failure of differentiation, which are hallmark processes in cancer development. This makes INI1 a significant factor in tumorigenesis when SMARCB1 is altered.

The other options mentioned do not directly relate to SMARCB1. EZH2 is a key component of the polycomb repressive complex and is involved in histone methylation, while the Hedgehog pathway and apoptosis are related to cellular signaling and programmed cell death, respectively, but do not directly involve the gene or protein product encoded by SMARCB1. Thus, the significance of INI1 in cancer development clearly highlights the relevance of SMARCB1's function in tumor biology