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Expression of insulin‐like growth factor binding proteins in human breast cancer correlates with estrogen receptor status
Author(s) -
Figueroa Jose A.,
Jackson James G.,
McGuire William L.,
Krywicki Robert F.,
Yee Douglas
Publication year - 1993
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/jcb.240520211
Subject(s) - estrogen receptor , breast cancer , insulin like growth factor binding protein , endocrinology , biology , medicine , estrogen , growth factor , messenger rna , insulin like growth factor , cancer research , insulin like growth factor 2 , receptor , cancer , gene , genetics
The insulin‐like growth factors (IGFs) have been implicated in the growth regulation of human breast cancer. Since the IGFs are associated with specific binding proteins (IGFBPs) which may modulate receptor/ligand interactions, production of IGFBPs by breast cancer cells could alter their IGF‐dependent growth. This study examined the expression of IGFBPs 4, 5, and 6 in eight breast cancer cell lines (BCCLs) using ribonuclease (RNase) protection assays. IGFBP‐4 mRNA was detected in all BCCLs studied. IGFBP‐5 expression was higher in estrogen receptor (ER) positive cells, while IGFBP‐6 mRNA was detected in only two ER negative BCCLs. We also found that E 2 treatment enhanced the expression of IGFBPs 2, 4, and 5 in T47‐D cells. We next studied IGFBP mRNA expression in 40 primary breast tumors. All tumors expressed mRNA for IGFBPs 2–6 but none expressed IGFBP‐1 message. IGFBP‐3 expression was higher in ER negative tumors, while that of IGFBP‐4 and ‐5 was higher in ER positive specimens. These differences were statistically significant ( P < .05). Ligand blot analysis of tumor extracts confirmed the presence of IGFBPs in breast cancer tissues. Thus, differential IGFBP expression in ER positive and negative tumors suggests an important role for this protein in breast cancer biology.