ErbB-4 ribozymes abolish neuregulin-induced mitogenesis.

Abstract

The epidermal growth factor-like receptor tyrosine kinase (ErbB) family is frequently overexpressed in a variety of human carcinomas, including breast cancer. To assist in characterizing the role of ErbB-4 in breast cancer, we generated three specific hammerhead ribozymes targeted to the ErbB-4 mRNA. These ribozymes, Rz6, Rz21, and Rz29, efficiently catalyzed the specific cleavage of ErbB-4 message in a cell-free system. We demonstrated that the neuregulin-induced mitogenic effect was abolished in ribozyme Rz29- and Rz6-transfected 32D/ErbB-4 cells. Inhibition of mitogenesis was characterized by ribozyme-mediated down-regulation of ErbB-4 expression. In addition, we provide the first evidence that different threshold levels of ErbB-4 expression and activation correlate with different responses to neuregulin stimulation. High levels of ErbB-4 expression, phosphorylation, and homodimerization are necessary for neuregulin-stimulated, interleukin 3-independent cell proliferation in the 32D/E4 cells. In the case of Rz29-transfected 32D/E4 cells, low levels of ErbB-4 expression allowed neuregulin-induced phosphorylation but were insufficient to couple the activated receptor to cellular signaling. Furthermore, expression of the functional ErbB-4 ribozyme in T47D human breast carcinoma cells led to a down-regulation of endogenous ErbB-4 expression and a reduction of anchorage-independent colony formation. These studies support the use of ErbB-4 ribozymes to define the role of ErbB-4 receptors in human cancers.

• Authors: C K Tang, D J Goldstein, J Payne, F Czubayko, M Alimandi, L M Wang, J H Pierce, M E Lippman
• Journal: Cancer research (Cancer Res) Vol. 58 Issue 15 Pg. 3415-22 (Aug 01 1998) ISSN: 0008-5472 [Print] United States
• PMID: 9699674 (Publication Type: Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Glycoproteins
• Interleukin-3
• Neuregulins
• RNA, Catalytic
• RNA, Messenger
• DNA
• ERBB4 protein, human
• ErbB Receptors
• Erbb4 protein, mouse
• Receptor, ErbB-4

Topics

• Animals
• Breast Neoplasms (enzymology, metabolism, pathology)
• Cell Division (drug effects, physiology)
• Cell-Free System
• Cells, Cultured
• DNA (biosynthesis)
• Down-Regulation
• ErbB Receptors (biosynthesis, metabolism, physiology)
• Glycoproteins (pharmacology)
• Hematopoietic System (cytology, enzymology)
• Humans
• Interleukin-3 (pharmacology)
• Mice
• Neuregulins
• Phosphorylation
• RNA, Catalytic (metabolism, pharmacology)
• RNA, Messenger (metabolism)
• Receptor, ErbB-4
• Stimulation, Chemical
• Substrate Specificity