SSX2

Overview

SSX2 (SSX Family Member 2) is a cancer-testis antigen gene located on chromosome Xp11, closely related to SSX1. It is a fusion partner with SS18 in the t(X;18)(p11;q11) translocation that defines synovial sarcoma. The SS18-SSX2 fusion protein, like SS18-SSX1, disrupts BAF (SWI/SNF) chromatin remodeling complex function. SSX2 is the less common fusion partner compared to SSX1 in synovial sarcoma.

Alterations observed in the corpus

  • t(X;18) SS18-SSX2 fusion present in a subset of synovial sarcoma (SS) cases in the TCGA pan-sarcoma cohort; SS18-SSX fusions (SSX1 or SSX2) present in 100% of SS PMID:29100075.

Cancer types (linked)

  • SS (Synovial Sarcoma) — SSX2 is a defining fusion partner in synovial sarcoma via t(X;18); the SS18-SSX2 fusion is pathognomonic for this tumor type PMID:29100075.

Co-occurrence and mutual exclusivity

  • Mutually exclusive with SSX1 as the SS18 fusion partner within a given tumor PMID:29100075.

Therapeutic relevance

  • SS18-SSX2 fusion disrupts BAF complex; EZH2 inhibitors and BET bromodomain inhibitors have preclinical rationale based on downstream epigenetic reprogramming PMID:29100075.

Open questions

  • Whether SS18-SSX1 vs SS18-SSX2 fusion confers differential prognosis or therapeutic sensitivity remains unresolved PMID:29100075.

Sources

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