Disruption of the apoptotic pathways may account for resistance to chemotherapy and treatment failures in human neoplastic disease. To further evaluate this issue, we isolated a HL-60 cell clone highly resistant to several drugs inducing apoptosis and to the differ entiating chemical all-trans-retinoic acid (ATRA). The resistant clone displayed an activated phosphoinositide 3-kinase (PI3K)/AKT1 pathway, with levels of phospha tidylinositol (3,4,5) trisphosphate higher than the paren tal cells and increased levels of both Thr 308 and Ser 473 phosphorylated AKT1. In vitro AKT1 activity was elevated in resistant cells, whereas treatment of the resistant cell clone with two inhibitors of PI3K, wort mannin or Ly294002, strongly reduced phosphatidyli nositol (3,4,5) trisphosphate levels and AKT1 activity. The inhibitors reversed resistance to drugs. Resistant cells overexpressing either dominant negative PI3K or dominant negative AKT1 became sensitive to drugs and ATRA. Conversely, if parental HL-60 cells were forced to overexpress an activated AKT1, they became resistant to apoptotic inducers and ATRA. There was a tight relationship between the activation of the PI3K/AKT1 axis and the expression of c-IAP1 and c-IAP2 proteins. Activation of the PI3K/AKT1 axis in resistant cells was dependent on enhanced tyrosine phosphorylation of the p85 regulatory subunit of PI3K, conceivably due to an autocrine insulin-like growth factor-I production. Our findings suggest that an up-regulation of the PI3K/AKT1 Received 6/18/02; revised 12/2/02; accepted 12/3/02. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. Grant support: Italian Miur Cofin 2001 and FIRB 2001 (S.C. and A.M.M.); CARISBO Foundation and Selected Topics Research Fund from Bologna University (A.M.M.); University of Ferrara local funds (L.M.N.); and I.S.S. Progetto Finalizzato Alzheimer and Finanziamento Centro Interuniversitario Biotecnologie (CIB) (S.C.). Requests for reprints: Alberto M. Martelli, Dipartimento di Scienze Anatomiche Umane e Fisiopatologia dell’Apparato Locomotore, Universita` di Bologna, via Irnerio 48, 40126 Bologna, Italy. Phone: 39-051-243103; Fax: 39-051-2091695. E-mail: amartell@biocfarm.unibo.it Copyright D 2003 American Association for Cancer Research. pathway might be one of the survival mechanisms responsible for the onset of resistance to chemother apeutic and differentiating therapy in patients with acute leukemia.
Neri, L.M., Borgatti, P., Tazzari, P.L., Bortul, R., Cappellini, A., Tabellini, G., et al. (2003). The phosphoinositide 3-kinase/AKT1 pathway involvement in drug and all-trans-retinoic acid resistance of leukemia cells. MOLECULAR CANCER RESEARCH, 1(3), 234-246.
The phosphoinositide 3-kinase/AKT1 pathway involvement in drug and all-trans-retinoic acid resistance of leukemia cells
Neri L. M.;Borgatti P.;Bortul R.;Cappellini A.;Martelli A. M.
2003
Abstract
Disruption of the apoptotic pathways may account for resistance to chemotherapy and treatment failures in human neoplastic disease. To further evaluate this issue, we isolated a HL-60 cell clone highly resistant to several drugs inducing apoptosis and to the differ entiating chemical all-trans-retinoic acid (ATRA). The resistant clone displayed an activated phosphoinositide 3-kinase (PI3K)/AKT1 pathway, with levels of phospha tidylinositol (3,4,5) trisphosphate higher than the paren tal cells and increased levels of both Thr 308 and Ser 473 phosphorylated AKT1. In vitro AKT1 activity was elevated in resistant cells, whereas treatment of the resistant cell clone with two inhibitors of PI3K, wort mannin or Ly294002, strongly reduced phosphatidyli nositol (3,4,5) trisphosphate levels and AKT1 activity. The inhibitors reversed resistance to drugs. Resistant cells overexpressing either dominant negative PI3K or dominant negative AKT1 became sensitive to drugs and ATRA. Conversely, if parental HL-60 cells were forced to overexpress an activated AKT1, they became resistant to apoptotic inducers and ATRA. There was a tight relationship between the activation of the PI3K/AKT1 axis and the expression of c-IAP1 and c-IAP2 proteins. Activation of the PI3K/AKT1 axis in resistant cells was dependent on enhanced tyrosine phosphorylation of the p85 regulatory subunit of PI3K, conceivably due to an autocrine insulin-like growth factor-I production. Our findings suggest that an up-regulation of the PI3K/AKT1 Received 6/18/02; revised 12/2/02; accepted 12/3/02. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. Grant support: Italian Miur Cofin 2001 and FIRB 2001 (S.C. and A.M.M.); CARISBO Foundation and Selected Topics Research Fund from Bologna University (A.M.M.); University of Ferrara local funds (L.M.N.); and I.S.S. Progetto Finalizzato Alzheimer and Finanziamento Centro Interuniversitario Biotecnologie (CIB) (S.C.). Requests for reprints: Alberto M. Martelli, Dipartimento di Scienze Anatomiche Umane e Fisiopatologia dell’Apparato Locomotore, Universita` di Bologna, via Irnerio 48, 40126 Bologna, Italy. Phone: 39-051-243103; Fax: 39-051-2091695. E-mail: amartell@biocfarm.unibo.it Copyright D 2003 American Association for Cancer Research. pathway might be one of the survival mechanisms responsible for the onset of resistance to chemother apeutic and differentiating therapy in patients with acute leukemia.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
