title: Activation of nuclear factor-kappa B pathway by simvastatin and RhoA silencing increases doxorubicin cytotoxicity in human colon cancer HT29 cells.
abstract: Doxorubicin efficacy in cancer therapy is hampered by the dose-dependent side effects, which may be overcome by reducing the drug's dose and increasing its efficacy. In the present work, we suggest that the activation of the nuclear factor-kappaB (NF-kappaB) pathway and of nitric-oxide (NO) synthase increases the doxorubicin efficacy in human colon cancer HT29 cells. To induce NF-kappaB, we took into account the effect of doxorubicin itself and of the 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor simvastatin; as NF-kappaB inhibitors, we chose the sesquiterpene lactones parthenolide and artemisinin. Simvastatin increased the NF-kappaB activity and NO synthesis, elicited the tyrosine nitration of the multidrug resistance-related protein 3, and enhanced the doxorubicin intracellular accumulation and cytotoxicity. Simvastatin potentiated the effect of doxorubicin on the NF-kappaB pathway and the inducible NO synthase expression. The effects of simvastatin were due to the inhibition of the small G-protein RhoA and of its effector Rho kinase. Parthenolide and artemisinin prevented all of the statin effects by inducing RhoA/Rho kinase activation. On the other hand, they did not reduce the NF-kappaB translocation and doxorubicin intracellular content when RhoA was silenced by small interfering RNA (siRNA). It is interesting that RhoA siRNA was sufficient to increase NF-kappaB translocation, NO synthase activity, doxorubicin accumulation, and cytotoxicity also in non-stimulated cells. Our results suggest that artemisinin, a widely used antimalarial drug, may impair the response to doxorubicin in colon cancer cells; on the contrary, simvastatin and RhoA siRNA may represent future therapeutic approaches to improve doxorubicin efficacy, reducing the risk of doxorubicin-dependent adverse effects.
authors.affiliation: Department of Genetics, Biology and Biochemistry, University of Torino, Italy. chiara.riganti@unito.it
authors.forename: Chiara
authors.initials: C
authors.lastname: Riganti
authors.forename: Sophie
authors.initials: S
authors.lastname: Doublier
authors.forename: Costanzo
authors.initials: C
authors.lastname: Costamagna
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Aldieri
authors.forename: Gianpiero
authors.initials: G
authors.lastname: Pescarmona
authors.forename: Dario
authors.initials: D
authors.lastname: Ghigo
authors.forename: Amalia
authors.initials: A
authors.lastname: Bosia
mesh_terms: D003110:Colonic Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism*; D004317:Doxorubicin / Q000494:pharmacology* / Q000627:therapeutic use; D004357:Drug Synergism; D020868:Gene Silencing / Q000187:drug effects* / Q000502:physiology; D019073:HT29 Cells; D006801:Humans; D016328:NF-kappa B / Q000378:metabolism* / Q000502:physiology; D034741:RNA, Small Interfering / Q000037:antagonists & inhibitors / Q000627:therapeutic use; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology; D019821:Simvastatin / Q000494:pharmacology* / Q000627:therapeutic use; D020742:rhoA GTP-Binding Protein / Q000037:antagonists & inhibitors* / Q000235:genetics* / Q000502:physiology
chemical_list: D016328:NF-kappa B; D034741:RNA, Small Interfering; D004317:Doxorubicin; D019821:Simvastatin; D020742:rhoA GTP-Binding Protein