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Ductal carcinoma in situ of the breast and heparanase-1 expression: a molecular explanation for more aggressive subtypes.
BACKGROUND: Ductal carcinoma in situ of the breast (DCIS) forms a heterogeneous group of lesions with varying invasive potential. This study tested whether heparanase-1 (HPR1), an endoglycosidase that specifically degrades the heparan sulfate (HS) proteoglycans in the breast extracellular matrix, was associated with the most aggressive DCIS subtypes.
STUDY DESIGN: Fifty-seven DCIS specimens and 10 normal breast specimens were examined for HPR1 expression using immunohistochemical staining. Twenty-seven arbitrarily selected specimens were also examined for HS deposition by immunofluorescence staining, confirming HPR1 activity. Patient medical records were obtained to explore a possible association between biologic potential using Van Nuys Prognostic Index (VNPI) and HPR1 expression.
RESULTS: Twenty-one (75%) of 28 comedo and microinvasive DCIS specimens stained HPR1 positive; 4 (14%) of 29 other subtypes (papillary, cribriform, and solid subtypes) stained HPR1 positive on immunohistochemistry (p = 0.003). Among 27 DCIS stained for HS, we found that 8 (67%) of 12 HPR1-negative DCIS had intact HS deposition in the extracellular basement membrane; none of the 15 HPR1-positive DCIS stained HS positive. Six (86%) of seven DCIS with VNPI scores 8 to 9 and 14 (50%) of 28 DCIS with VNPI scores 5 to 7 were HPR1 positive; only 3 (17%) of 18 DCIS with VNPI scores 3 to 4 were HPR1 positive. Median VNPI score in patients with HPR1-positive DCIS was 7 (range 3 to 9), compared with 4.5 (range 3 to 7) in patients with HPR1-negative DCIS (p < 0.001).
CONCLUSIONS: HPR1 was expressed at a significantly higher frequency in the invasive comedo and DCIS with microinvasion subtypes than in the noninvasive subtypes. HPR1 expression was inversely associated with HS deposition in the extracellular basement membrane of the DCIS. HPR1 expression was associated with a higher VNPI score. These observations suggest that HPR1 expression in DCIS can play an important role in development of DCIS into an invasive breast cancer.
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