Cellular $~all#tf Vol.5, No. 3, pp. 331-336, 1993. 0698--6568/93 $6.00 + 0.00 Printed in Great Britain. © 1993 Pergamon Press Lid INOSITOL LIPID-MEDIATED INTRANUCLEAR SIGNALLING: A COMPARATIVE ANALYSIS OF IN VIVO LABELLING IN INTERFERON ALPHA-SENSITIVE AND -RESISTANT DAUDI LYMPHOMA CELLS AMELIA CATALDI,* ROBERTO DI PRIMIO,* RENATO LISIO,* ROSA ALBA RANA,* IOLE ROBUFFO,'~ DOMENICO Boscot and S~ASTIANO MISCIA~ Istituto di Morfologia Umana Normale, Universit~ G, D'Annunzio, Chieti, Italy and tIstituto di Citomorfologia Normale e Patologica del CNR, Chiefti, Italy (Received 14 October 1992; and accepted 22 December 1992) Al~Jtract----Changes in inositol lipid and diacylglycerol metabolism have been analysed in Daudi lymphoma cells treated up to 24 h with human DNA recombinant interferon alpha. Results showing a different response of nuclear phosphoinositides and diacylglycerol, compared to whole cells, suggest that the intranuclear signalling system activated by interferon in Daudi cells involves nuclear inositol lipid metabolism. A well- characterized clone of Daudi cells selected for resistence to the antiprofiferative action of interferon provided controls for the specificity of results. Key words: Interferon, inositol lipids, Daudi cells, cell growth, nucleus. INTRODUCTION THE GROWTH inhibitory effect of type I inter- ferons (alpha and beta), as well as the capability of interfering with viral replication in infected cells through modulations on protein synthesis, identifies interferons as potential tumour suppressors [1-2]. Although much is known of the biological effects exerted by interferon on sensitive and resistant lines, less is known of the molecular mechanisms which occur upon inter- action between interferon and cell surface receptors finally leading to the modulation of tumour cell growth [3-4]. Among the metabolic pathways involved in cellular signalling, the hydrolysis of a membrane-bound phosphatidylinositol-4,5- bisphosphate (PIPz), producing two second messengers, diacylglycerol (DAG) and inositol- trisphosphate (IP3), has been largely evidenced :[:Author to whom correspondence should be addressed at: Sebastiano Miscia, lstituto di Morfoiogia Umana Normale, Universit~ G. D'Annunzio, Via dei Vestini, 6, 66100 Chieti, Italy. 331 with a key role in the control of several activi- ties such as secretion, contraction and prolifera- tion [5]. The presence of inositol lipids within the nucleus and changes in their metabolism in response to interferon-generated signals in different cell lines have hinted at an important role for inositol lipid metabolites in the trans- duction of the interferon-generated signals into the nucleus [6]. In this paper we report evidence that PIP 2 labelling in vivo is early and transiently modi- fied upon interferon treatment in sensitive Daudi cells derived from 16-year-old Negro males with Burkitt lymphoma (Flow Laboratories). These changes precede or are concomitant with other metabolic events occur- ring at the nucleus, such as changes in DAG mass. A characterized clone of Daudi cells selected for resistance to the antiproliferative effect of interferon [7] alpha does not show any of the above-mentioned changes. All in all, it is suggested that one of the molecular pathways which interferon uses in the nucleus for modu- lating metabolism of infected cells might be represented by inositol lipids.