Farnesyltransferase Inhibitors Induce DNA Damage via Reactive Oxygen Species in Human Cancer Cells

Abstract

Farnesyltransferase inhibitors (FTIs) possess antitumor activity. Based on recent findings, we hypothesized that FTIs induce reactive oxygen species (ROS) that damage DNA, leading to DNA damage responses. To test this hypothesis, we investigated the effects of FTIs on the generation of ROS, DNA double-strand breaks (DSB), DNA damage responses, and RhoB, and the effects of quenching ROS on these FTI effects. We evaluated four FTIs in human cancer cell lines of different tissue origins. We found that FTIs induced ROS and DSBs. Suppressing expression of the B-subunit of farnesyltransferase with siRNA did not induce ROS, but slightly attenuated the ROS induced by FTIs. N-acetyl-L-cysteine (NAC), but not caspase inhibitors, blocked FTI-induced DSBs, suggesting that the DSBs were caused by ROS and did not result from apoptosis. The DSBs led to DNA damage responses. H2AX became phosphorylated and formed nuclear foci. The DNAdamage-sensing molecules involved were probably ataxiatelangiectasia mutated protein (ATM) and DNA-dependent protein kinase (DNA-PK) but not ATM-and Rad3-related protein (ATR). Key components of the homologous recombination and nonhomologous end joining repair pathways (DNA-PK, BRCA1, and NBS1) underwent phosphorylation and formed nuclear foci. RhoB, a mediator of the antineoplastic effect of FTIs and a protein inducible by DNA damage, was increased by FTIs. This increase was blocked by NAC. We concluded that FTIs induced oxidative DNA damage by inducing ROS and initiated DNA damage responses, including RhoB induction, and there was a complex relationship among FTIs, farnesyltransferase, ROS, and RhoB. Our data also imply that inhibitors of DNA repair may accentuate the clinical efficacy of FTIs. (Cancer Res 2005; 65(9): 3671-81)

Farnesyltransferase and geranylgeranyltransferase I inhibitors upregulate RhoB expression by HDAC1 dissociation, HAT association and histone acetylation of the RhoB promoter

“…The induction of RhoB by FTI-277 and GGTI-298 was observed in different types of human cancer-derived cell lines, suggesting that RhoB induction is not tumor type specific. Our results are consistent with those of Pan et al (2005), who showed that FTIs induce reactive oxygen species that damage DNA and upregulate RhoB levels. The results are also consistent with a report showing that lovastatin (HMGCoA reductase inhibitor), which inhibits protein farnesylation and geranylgeranylation by depleting FPP and GGPP, also upregulated RhoB expression (Holstein et al, 2002a).…”

Reactive oxygen species‐dependent destruction of MEK and Akt in Manumycin stimulated death of lymphoid tumor and myeloma cell lines

“…16 However, we found that not only were lymphoma cells exquisitely sensitive to Man-A, at 4 lM, the compound induced ROS and caused oligosomal DNA banding, a caspase-dependent process. 37 On the other hand, the exogenous addition of concentrations of H 2 O 2 to achieve intracellular H 2 O 2 and AEO 2 2 levels equal to those stimulated by Man-A resulted in DNA degradation, an indicator of necrosis-related DNA damage.…”

“…16 We examined the effect of Man-A on WEHI-231, an extensively characterized B lymphoma model, [22][23][24] and found that these cells underwent apoptosis and were 10 times more sensitive to Man-A than anaplastic thyroid-and breast-cancer cells. 16 The IC 50 for Man-A-mediated apoptosis, as determined by the appearance of <2N nuclei, was 2 lM (Fig. 1a).…”

Activity of tyrosine kinase inhibitors against human NUP214-ABL1-positive T cell malignancies

“…Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting were previously described. 19 NUP214-ABL1-positive leukemia xenograft murine model ALL-SIL cells or HPB-ALL were suspended (2 Â 10 8 cells ml À1 ) in RPMI-1640 medium. In all 0.1 ml of the suspension was injected subcutaneously into the ventral axillary region of female NOD/ SCID mice (Harlan, IN, USA).…”