Purpose: We examined a cohort of patients with alveolar soft part sarcoma (ASPS) treated at our institution and showed the characteristic ASPSCR1-TFE3 fusion transcript in their tumors. Investigation of potential angiogenesis-modulating molecular determinants provided mechanistic and potentially therapeutically relevant insight into the enhanced vascularity characteristic of this unusual tumor.
Experimental design: Medical records of 71 patients with ASPS presenting at the University of Texas M.D. Anderson Cancer Center (1986-2005) were reviewed to isolate 33 patients with formalin-fixed paraffin-embedded material available for study. RNA extracted from available fresh-frozen and formalin-fixed paraffin-embedded human ASPS tumors were analyzed for ASPSCR1-TFE3 fusion transcript expression using reverse transcription-PCR and by angiogenesis oligomicroarrays with immunohistochemical confirmation.
Results: Similar to previous studies, actuarial 5- and 10-year survival rates were 74% and 51%, respectively, despite frequent metastasis. ASPSCR1-TFE3 fusion transcripts were identified in 16 of 18 ASPS samples. In the three frozen samples subjected to an angiogenesis oligoarray, 18 angiogenesis-related genes were up-regulated in tumor over adjacent normal tissue. Immunohistochemistry for jag-1, midkine, and angiogenin in 33 human ASPS samples confirmed these results. Comparison with other sarcomas indicates that the ASPS angiogenic signature is unique.
Conclusion: ASPS is a highly vascular and metastatic tumor with a surprisingly favorable outcome; therapeutically resistant metastases drive mortality. Future molecular therapies targeting overexpressed angiogenesis-promoting proteins (such as those identified here) could benefit patients with ASPS.