C A NC ER LETTERS Cancer Letters 77 (1994) 25-32 Detection of insulin-like growth factor binding proteins (IGFBPs) by ligand blotting in breast cancer tissues Sean E. McGuire, Susan G. Hilsenbeck, Jos& A. Figueroa, James G. Jackson, Douglas Yee* zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPO Depcrrrmenr zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA of Medicine, Division of Medial Oncology. Unisersiiy of Texas Heullil Science Center at San Antonio. Sun Antonio. TX 78284-7884. LISA (Received 12 November 1993; revision received 18 November 1993; accepted 19 November 1993) zyxwvutsrqponmlkjihgfed Abstract Eighty breast cancer specimens were examined for insulin-like growth factor binding protein (IGFBP) expression by ligand blotting. Five distinct IGFBP species were found: a doublet at 48 and 44 kDa was IGFBP-3, the 34-kDa band was IGFBP-2, and a band at 24 kDa was IGFBP-4. A 32-kDa band was compatible with the migration position reported for IGFBP-5. IGFBP-3 was inversely correlated with ER expression, while IGFBP-4 was positively correlated with both ER and PgR. IGFBP-4 was also inversely correlated with S-phase fraction, Thus, IGFBP expression cor- relates with other parameters of breast cancer biology and may play a role in regulating tumor growth. Kqv words: Breast cancer; Insulin-like growth factor binding proteins; Estrogen receptor; Progesterone receptor; S-phase fraction 1. Introduction The insulin-like growth factors (IGFs) have been implicated in the autocrine and paracrine growth regulation of human breast cancer [ 1,2]. Involved in this pathway is a family of six distinct high affinity binding proteins (IGFBPs) that mediate the interaction of the IGFs with their receptor [3.4]. Although the precise biological function of each IGFBP species remains unclear. some species have been shown to both potentiate and inhibit the cellular actions of IGFs in different experimental systems [5-71. * Corresponding author. Recently, we and others have shown that all six IGFBPs are produced by breast cancer cell lines, and their pattern of expression correlates with the cellular estrogen receptor (ER) status [8- 131. We have also shown that IGFBP RNA expression in breast tumor specimens correlates with ER status [14]. The heterogeneous pattern of expression of IGFBPs, their correlation with ER status and their induction by estrogen suggest that some of these binding proteins may be under hormonal regula- tion [8,14,15]. To determine if we could detect IGFBPs in breast cancer tissue extracts, we examined the expression of IGFBPs in 80 breast tumors by ligand blotting and correlated their levels with 0304-3835/94/$06.00 0 1994 Elsevier Scientific Publishers Ireland Ltd. All rights reserved SSDI 0304-3835(93)03241-V