The farnesyl transferase inhibitor R115777 (Zarnestra) synergistically enhances growth inhibition and apoptosis induced on epidermoid cancer cells by Zoledronic acid (Zometa) and Pamidronate.
Pamidronate (PAM) and zoledronic acid (ZOL) are aminobisphosphonates (BPs) able to affect the isoprenylation of intracellular small G proteins. We have investigated the antitumor activity of BPs and R115777 farnesyl transferase inhibitor (FTI) against epidermoid cancer cells. In human epidermoid head and neck KB and lung H1355 cancer cells, 48 h exposure to PAM and ZOL induced growth inhibition (IC(50) 25 and 10 microM, respectively) and apoptosis and abolished the proliferative and antiapoptotic stimuli induced by epidermal growth factor (EGF). In these experimental conditions, ZOL induced apoptosis through the activation of caspase 3 and a clear fragmentation of PARP was also demonstrated. A strong decrease of basal ras activity and an antagonism on its stimulation by EGF was recorded in the tumor cells exposed to BPs. These effects were paralleled by impaired activation of the survival enzymes extracellular signal regulated kinase 1 and 2 (Erk-1/2) and Akt that were not restored by EGF. Conversely, farnesol induced a recovery of ras activity and antagonized the proapoptotic effects induced by BPs. The combined treatment with BPs and R115777 resulted in a strong synergism both in growth inhibition and apoptosis in KB and H1355 cells. The synergistic activity between the drugs allowed BPs to produce tumor cell growth inhibition and apoptosis at in vivo achievable concentrations (0.1 micromolar for both drugs). Moreover, the combination was highly effective in the inhibition of ras, Erk and Akt activity, while farnesol again antagonized these effects. In conclusion, the combination of BPs and FTI leads to enhanced antitumor activity at clinically achievable drug concentrations that resides in the inhibition of farnesylation-dependent survival pathways and warrants further studies for clinical translation.
Department of Biochemistry and Biophysics, II University of Naples, Via Costantinopoli no 16, 80138 Naples, Italy. Michele.Caraglia@unina2.it
Michele
M
Caraglia
Anna Maria
AM
D'Alessandro
Monica
M
Marra
Gaia
G
Giuberti
Giovanni
G
Vitale
Caterina
C
Viscomi
Annamaria
A
Colao
Salvatore Del
SD
Prete
Pierosandro
P
Tagliaferri
Pierfrancesco
P
Tassone
Alfredo
A
Budillon
Salvatore
S
Venuta
Alberto
A
Abbruzzese
D019883:Alkyl and Aryl Transferases / Q000037:antagonists & inhibitors*; D017209:Apoptosis / Q000187:drug effects*; D020169:Caspases / Q000502:physiology; D002455:Cell Division / Q000187:drug effects; D004164:Diphosphonates / Q000494:pharmacology*; D004357:Drug Synergism; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D004815:Epidermal Growth Factor / Q000494:pharmacology; D051231:Farnesyltranstransferase; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology*; D007624:KB Cells / Q000166:cytology / Q000187:drug effects*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D000077268:Pamidronate; D017368:Protein Prenylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D015363:Quinolones / Q000494:pharmacology*; D000077211:Zoledronic Acid
D004164:Diphosphonates; D004791:Enzyme Inhibitors; D007093:Imidazoles; D011518:Proto-Oncogene Proteins; D015363:Quinolones; D004815:Epidermal Growth Factor; D000077211:Zoledronic Acid; D019883:Alkyl and Aryl Transferases; D051231:Farnesyltranstransferase; C494918:AKT1 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D020928:Mitogen-Activated Protein Kinases; D020169:Caspases; C402769:tipifarnib; D000077268:Pamidronate