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Pregnancy‐associated alpha 2 glycoprotein (α 2 PAG) synthesis by human breast cancer tissue and cultured cell lines
Author(s) -
Sarcione Edward J.,
Delluomo Daniel,
Zloty Martin
Publication year - 1983
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.2910310203
Subject(s) - breast cancer , cancer , ca 15 3 , ca15 3 , in vitro , cancer research , cancer cell , glycoprotein , in vivo , mammary gland , immunology , biology , medicine , pathology , microbiology and biotechnology , biochemistry , genetics
Elevated α 2 PAG serum levels are found in pregnant women and patients with diverse types of neoplasms including breast cancer. Primary human breast cancer tissue, MCF‐7 and BT‐20 human breast cancer cultured cell lines were shown to synthesize α 2 PAG in vitro . BT‐20 breast cancer cells also released this pregnancy‐associated protein. Synthesis was demonstrated by l‐[ 14 C]‐leucine incorporation into immunochemically isolated protein and confirmed by radioimmunodiffusion and radioimmuno‐electrophoresis. These data (1) provide direct evidence for α 2 PAG synthesis by well‐characterized human breast cancer cells per se; (2) strongly suggest that at least part of the α 2 2PAG synthesis observed in primary human breast cancer tissue in vitro was due specifically to breast cancer cells rather than exclusively to monocytes/mac‐rophages known to infiltrate neoplastic tissues and to produce this protein during pregnancy; and (3) are consistent with the conclusion that serum α 2 PAG is a definite breast cancer “marker protein” which originates from and reflects breast cancer status. On the basis of the association of elevated serum α 2 PAG levels in breast cancer patients, its known immunosuppressive activity in vitro , and the direct evidence for α 2 PAG synthesis by human breast cancer cells perse , we postulate that this protein plays an important immunoregulatory role in vivo to prevent immune rejection and/or destruction of breast cancer cells.