Laminin 332 expression in mammary cell lines

Abstract

Laminin 332 (LN332), produced by normal mammary epithelium, can induce motility and invasion in breast cancer cells. Although down regulated in most breast carcinomas, LN332 is present in triple negative (TN) carcinomas, those without estrogen (ER) and progesterone receptors (PR) and no HER2 gene amplification. Thus, we sought to determine LN332 expression patterns in breast carcinoma lines, including the ER positive (MCF‐7), HER2 gene amplified (SKBR3), and TN (BT‐20, MDA‐MB‐231) carcinomas, and immortalized normal breast epithelium (184A1). By immunoperoxidase and Western blotting, 184A1, MDA‐MB‐231 and to a lesser extent, BT‐20 showed LN332 β3 chain staining. No expression was detected for SKBR3 or MCF‐7. By RT‐PCR, MDA‐MB‐231 expression of all LN332 chains was higher than in MCF‐7 and BT‐20, but less than the values for 184A1. Finally, to determine if the cell lines' LN332 was sufficient to induce motility, serum‐free conditioned medium (CM) from all lines was incubated with MCF‐7, and scattering was measured. Only 184‐A1 and MDA‐MB‐231 CM induced motility, but antibodies against α3 integrin, which mediates LN332 motility in MCF‐7, only inhibited 184‐A1 induced motility, indicating that other motility factors may be produced by MDA‐MB‐231. In summary, LN332 protein was only measurable in BT‐20 and MDA‐MB‐231, both of which are TN tumors, and thus may prove useful for the study of LN332 in breast cancer.