[Lani]

a study showing her2+ breast cancer has positive feedback loop joining her2,beta-adrenergic receptor

again, a beta blocker here would probably inhibit her2+ breast cancer if things are not more complicated...

Breast Cancer Res Treat. 2010 Mar 17. [Epub ahead of print]
The beta2-adrenergic receptor and Her2 comprise a positive feedback loop in human breast cancer cells.
Shi M, Liu D, Duan H, Qian L, Wang L, Niu L, Zhang H, Yong Z, Gong Z, Song L, Yu M, Hu M, Xia Q, Shen B, Guo N.

Department of Molecular Immunology, Institute of Basic Medical Sciences, Taiping Road 27, 100850, Beijing, People's Republic of China.
In this study, beta2-AR level was found to be up-regulated in MCF-7 cells overexpressing Her2 (MCF-7/Her2). Correlation of beta2-AR level with Her2 status was demonstrated in breast cancer tissue samples. Constitutive phosphorylation of ERK, mRNA expression up-regulation of catecholamine-synthesis enzymes, and increased epinephrine release were detected in MCF-7/Her2 cells. beta2-AR expression induced by epinephrine and involvement of ERK signaling were validated. The data indicate that Her2 overexpression and excessive phosphorylation of ERK cause epinephrine autocrine release from breast cancer cells, resulting in up-regulation of beta2-AR expression. The data also showed that catecholamine prominently stimulated Her2 mRNA expression and promoter activity. The activation and nuclear translocation of STAT3 triggered by isoproterenol were observed. Enhanced binding activities of STAT3 to the Her2 promoter after isoproterenol stimulation were verified. Using STAT3 shRNA and dominant negative STAT3 mutant, the role of STAT3 in isoproterenol-induced Her2 expression was further confirmed. The data support a model where beta2-AR and Her2 comprise a positive feedback loop in human breast cancer cells.

PMID: 20237834