Interference of transcriptional activation by the antineoplastic drug ecteinascidin-743

^*Dipartimento di Genetica e di Biologia dei Microrganismi, Università degli Studi di Milano, Via Celoria 26, 20133 Milano, Italy; ^†Dipartimento di Oncologia, Istituto di Ricerche Farmacologiche Mario Negri, Via Eritrea 62, 20157 Milano, Italy; ^‡PharmaMar USA, 320 Putnam Avenue, Cambridge, MA 02139; and ^§Dipartimento di Biologia Animale, Università di Modena e Reggio, Via Berengario 14, 41100 Modena Italy

Edited by Samuel J. Danishefsky, Memorial Sloan–Kettering Cancer Center, New York, NY, and approved April 3, 2000 (received for review November 29, 1999)

Abstract

Ecteinascidin-743 (ET-743) is a tetrahydroisoquinoline alkaloid isolated from the tunicate Ecteinascidia turbinata currently under phase II clinical trials for its potent anticancer activity. ET-743 binds DNA in the minor groove and forms covalent adducts with some sequence specificity. It selectively inhibits in vitro binding of the CCAAT box factor NF-Y. In this study, we assayed ET-743 function in vivo on the HSP70 promoter. On heat induction, the drug blocks transcription rapidly at pharmacological concentrations and in a CCAAT-dependent manner, whereas the activity of the CCAAT-less simian virus 40 promoter is not affected. The effect is exerted at the mRNA level. The distamycin-like alkylating tallimustine is inactive in these assays. Binding of NF-Y and of the heat-shock factor is normal in ET-743-treated cells. Run-on analysis of several endogenous genes further proves that the drug has rapid, profound, and selective negative effects on transcription. Thus, this marine-derived compound is a promoter-specific, transcription-interfering agent.

Footnotes

↵ ¶ To whom reprint requests should be addressed. E-mail: mantor{at}mailserver.unimi.it.
This paper was submitted directly (Track II) to the PNAS office.
Abbreviations:

ET-743,

ecteinascidin-743;

CAT,

chloramphenicol acetyltransferase;

HSE,

heat-shock element;

HSF,

heat-shock factor