OBJECTIVETo evaluate the expression pattern of PH20 in primary and metastatic breast cancer and its relationship to tumor metastatic potential.

METHODSAnti-PH20 antibody was synthesized by injection of conjugated human PH20 peptides into rabbits. Immunohistochemical study was performed on 53 cases of human breast cancer. Western blot was used to detect PH20 expression in 5 cases of breast cancer with available fresh tissue. Two oligonucleotide probes were prepared for in-situ hybridization using breast tissue microarray.

RESULTSNormal breast tissue did not express PH20 (0/3), while 58.4% (31/53) of breast cancer cases did. The highest expression rate was found in metastatic foci in regional lymph nodes (83.3%), followed by primary breast cancer tissue in cases with lymph node secondaries (70.8%). The breast cancer cases with no any metastasis had an expression rate of 48.2%. The immunohistochemical staining results were further confirmed by Western blotting. In-situ hybridization showed PH20 RNA in 75% of the breast cancer tissue (21/28). Two of the 17 cases of normal breast tissue showed weak expression in some ductolobular units.

CONCLUSIONSThe expression of PH20 has a positive correlation with metastatic potential in breast cancer. It is possible that PH20 may play an important role in the invasive growth and metastasis of breast cancer cells, via mechanisms such as digestion of surrounding stromal tissue and release of FGF-2.