STAR

Overview

STAR (Steroidogenic Acute Regulatory Protein) encodes a mitochondrial transport protein that facilitates the rate-limiting step of steroidogenesis: cholesterol delivery to the inner mitochondrial membrane for conversion by CYP11A1. STAR is a marker of adrenal cortical identity. In the context of pheochromocytoma/paraganglioma, STAR overexpression identifies a molecular subtype characterized by contaminating adrenal cortical tissue.

Alterations observed in the corpus

  • STAR is overexpressed (along with CYP11B1 and CYP21A2) in the cortical admixture mRNA subtype of pheochromocytoma/paraganglioma (PCC/PGL) in the TCGA cohort (pcpg_tcga_pub, n=173). These markers reflect histologically interspersed adrenal cortical cells rather than a tumor-intrinsic transcriptional program. PMID:28162975

Cancer types (linked)

  • PHC / PGNG: STAR overexpression is a marker of the cortical admixture mRNA subtype; this subtype has reduced tumor purity, elevated leukocyte infiltration, and an association with histologically interspersed cortical cells (p < 5e-5). Both germline MAX mutations in the cohort occurred in this subtype (p < 0.032). PMID:28162975

Co-occurrence and mutual exclusivity

Therapeutic relevance

  • No direct therapeutic implications for STAR expression in PCC/PGL described in the corpus.

Open questions

  • Whether the cortical admixture subtype (marked by STAR overexpression) reflects a tissue-sampling artifact from interspersed cortical cells versus a genuine tumor-biology subtype remains unresolved; the authors hypothesize a multifocal MAX-mutant context but note this cannot be confirmed. PMID:28162975

Sources

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