Key peptide processing enzymes are expressed by breast cancer cells

The expression of the three key peptide processing enzyme families, represe nted by CPE, PAM, and PC1/3 plus PC2, were examined in MCF-7 and ZR-75-1 br east cancer cell lines. Both of these cell lines express vasopressin recept ors as well as the vasopressin gene, but the processing of vasopressin gene -related proteins appears to be Limited. Products of the expected size for, CPE, PAM and PC1/PC3 could be amplified by reverse transcription-polymeras e chain reaction (RT-PCR) from both cell lines. Cloning and sequencing of t hese RT-PCR products revealed that each enzyme mRNA had a structure identic al to that published for the human form of the respective enzyme. Western a nalysis provided evidence that mRNAs for these enzymes are translated into proteins. Alternatively, PC2 mRNA was identified to be present in MCF-7 cel ls both by RT-PCR and Western blot analysis, but could not be demonstrated for ZR-75-1 cells. Our findings suggest that the key processing enzymes nee ded to generate active vasopressin and other neuropeptide growth factors ar e present in breast cancer cells. (C) 2001 Elsevier Science Ireland Ltd. Al l rights reserved.