Down-regulation of RIα subunit of cAMP-dependent protein kinase induces growth inhibition of human mammary epithelial cells transformed by c-Ha-ras and c-erbB-2 proto-oncogenes

F. Ciardiello, S. Pepe, C. Bianco, G. Baldassarre, A. Ruggiero, C. Bianco, M. P. Selvam, A. R. Bianco, G. Tortora

Research output: Contribution to journalArticle

Abstract

MCF-10A is a spontaneously immortalized, non-transformed human mammary epithelial cell line. We have recently obtained MCF-10A clones (MCF-10A HE cells) that are transformed following over-expression of both a human point-mutated c-Ha-ras and the c-erbB-2 proto-oncogenes. Two isoforms of the cAMP-dependent protein kinase (cAK) have been described in mammalian cells. Enhanced levels of type-I cAK (cAKI) are generally found in tumor cells. To determine whether inhibition of cAKI expression may interfere with ras and erbB-2 oncogene-induced transformation of human mammary epithelial cells, we have tested the effects of 2 agents that specifically down-regulate cAKI, such as 8-chloro-cAMP and an anti-sense oligodeoxynucleotide targeted against the RIα regulatory subunit of cAKI on MCF-10A HE cells. Treatment of MCF-10A HE cells with 8-chloro-cAMP induces a dose-dependent growth inhibition under both monolayer and soft-agar growth conditions, that is correlated with an accumulation of MCF-10A HE cells in G0/G1 phases of the cell cycle and a reduction of the number of cells in S phase. In contrast, 8-chloro-cAMP has no effect on MCF-10A cell growth. Furthermore, 8-chloro-cAMP treatment of MCF-10A HE cells induces a 4- to 6-fold reduction in p185erbB-2 expression and brings p21 ras expression to levels comparable to those found in MCF-10A cells. Treatment of MCF-10A HE cells with an RIα anti-sense oligodeoxynucleotide determines acomparable inhibition of both anchorage-dependent and anchorage-independent cell growth. Our results suggest that cAKI may act as a mediator of ras and erbB-2 oncogene action in human breast cells and that interference with cAKI action provides a potential tool for inhibiting the growth-promoting effects of these oncogenes.

Original languageEnglish
Pages (from-to)438-443
Number of pages6
JournalInternational Journal of Cancer
Volume53
Issue number3
DOIs
Publication statusPublished - 1993

ASJC Scopus subject areas

  • Cancer Research
  • Oncology

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