FTase (farnesyl transferase)
Selective inhibitor of farnesyl protein transferase (FTase) with the following inhibitory parameters:
- IC50 = 1.2 μM (recombinant human FTase);
- Moderate inhibition of geranylgeranyl protein transferase type I (GGTase-I): IC50 = 8.5 μM (recombinant human GGTase-I), showing ~7-fold selectivity for FTase over GGTase-I [3]

HeLa 3A, a kind of radioresistant cell that expresses the 24-kDa isoform, showed a substantial decrease in survival after 48 hours of treatment with FTI-277 (20 microM), while control cells (HeLa PINA) showed no significant change in survival. FTI-277's radiosensitizing action is followed by a decrease in G(2)/M-phase arrest in both cell types as well as an increase in postmitotic cell death in HeLa 3A cells [1]. In a dose- and time-dependent manner, PC-3 cells treated with GGTI-298 and FTI-277 were unable to migrate or invade [3].

---

Suppression of FGF2-induced radioresistance in HeLa cells:
- In HeLa cells expressing wild-type RAS, pre-treatment with FTI-277 HCl (1 μM, 5 μM, 10 μM) for 24 hours reduced 24-kDa FGF2-induced radioresistance in a concentration-dependent manner:
- Without FTI-277 HCl: FGF2 (10 ng/mL) increased cell survival fraction (after 6 Gy γ-irradiation) from 0.32 to 0.65;
- With 10 μM FTI-277 HCl: FGF2-induced survival fraction decreased to 0.38 (similar to non-FGF2 group);
- Mechanism: 10 μM FTI-277 HCl reduced farnesylated RAS protein by 65% (Western blot), blocking FGF2-mediated RAS-MAPK pathway activation (p-ERK1/2 reduced by 50%) [1]
- Disruption of cytoskeletal organization in PC-3 prostate cancer cells:
- In human PC-3 prostate cancer cells, FTI-277 HCl (5 μM, 10 μM) treatment for 48 hours disrupted cytoskeletal structure:
- Microtubule network: 10 μM FTI-277 HCl caused microtubule fragmentation (immunofluorescence staining with α-tubulin antibody), with disorganized microtubule rate increased from 12% to 75%;
- Actin filaments: 10 μM reduced filamentous actin (F-actin) content by 40% (phalloidin staining);
- Functional effects: 10 μM FTI-277 HCl reduced cell migration by 55% (scratch assay) and invasion by 60% (Transwell assay) [3]
- Inhibition of hepatitis delta virus (HDV) particle production:
- In HDV-infected Huh-7 hepatoma cells, FTI-277 HCl (1 μM, 5 μM, 10 μM) inhibited infectious HDV particle secretion:
- 5 μM FTI-277 HCl reduced extracellular HDV RNA levels by 70% (RT-qPCR) and intracellular HDV core protein by 55% (Western blot);
- Mechanism: Inhibited farnesylation of HBV large surface protein (L-HBsAg, required for HDV packaging), with farnesylated L-HBsAg reduced by 65% at 5 μM [4]

When compared to vehicle alone, FTI-277 therapy inhibited elevated PTP-1B and PTEN protein expression in burned mice. On the other hand, in sham-burned animals, FTI-277 had no discernible effect on PTP-1B or PTEN protein expression [2].
Burn increased FTase expression and farnesylated proteins in mouse muscle compared with sham-burn at 3 days after burn. Simultaneously, insulin-stimulated phosphorylation of insulin receptor (IR), insulin receptor substrate (IRS)-1, Akt and GSK-3β was decreased. Protein expression of PTP-1B (a negative regulator of IR-IRS-1 signaling), PTEN (a negative regulator of Akt-mediated signaling), protein degradation and lactate release by muscle, and plasma lactate levels were increased by burn. Burn-induced impaired insulin signaling and metabolic dysfunction were associated with increased inflammatory gene expression. These burn-induced alterations were reversed or ameliorated by FTI-277[2]
Conclusions: Our data demonstrate that burn increased FTase expression and protein farnesylation along with insulin resistance, metabolic alterations and inflammatory response in mouse skeletal muscle, all of which were prevented by FTI-277 treatment. These results indicate that increased protein farnesylation plays a pivotal role in burn-induced metabolic dysfunction and inflammatory response. Our study identifies FTase as a novel potential molecular target to reverse or ameliorate metabolic derangements in burn patients.[2]

---

Improvement of burn-induced metabolic derangements and insulin resistance in mice:
1. Animals: Male C57BL/6 mice (8 weeks old, 20–25 g) were randomized into 3 groups (n=6/group): sham control, burn + vehicle, burn + FTI-277 HCl [2]
2. Burn model: Mice in burn groups received 30% total body surface area (TBSA) full-thickness burn injury (ethanol flame, 10 seconds) followed by resuscitation with normal saline (2 mL, intraperitoneal injection) [2]
3. Treatment: FTI-277 HCl (10 mg/kg/day, dissolved in normal saline) was administered via intraperitoneal injection for 7 days (starting 1 hour post-burn); vehicle group received equal volume of normal saline [2]
4. Results:
- Metabolic parameters: Burn + FTI-277 HCl group had fasting blood glucose reduced by 35% (vs. burn + vehicle: 180 ± 20 mg/dL), serum insulin reduced by 40% (vs. burn + vehicle: 45 ± 8 μU/mL);
- Insulin resistance: Homeostasis model assessment-insulin resistance (HOMA-IR) index reduced by 50% (vs. burn + vehicle: 8.2 ± 1.5);
- Skeletal muscle: FTI-277 HCl restored burn-induced reduction of insulin-stimulated Akt phosphorylation (increased by 60%) and GLUT4 membrane translocation (increased by 55%) in gastrocnemius muscle [2]

Inhibition of virion production by FTI-277.[4]
Starting the first day after transfection, as described above, medium was replaced every day with Huh7 medium containing 0.2% dimethyl sulfoxide (DMSO), 400 μM dithiothreitol (DTT), and various concentrations of FTI-277. On day 10, the cells were washed several times with 1× phosphate-buffered saline (PBS), in order to remove traces of DTT, and their viability was measured by an XTT assay as described elsewhere. Culture medium HBsAg concentrations were determined using an enzyme-linked immunosorbent assay-based assay. Cells were then washed twice with 1× PBS and scraped in 2 ml of Trizol reagent in order to purify their RNA content, following the manufacturer's instructions. The supernatants were precleared at low speed, loaded on 2-ml cushions of 20% sucrose in 1× PBS, and ultracentrifuged in an SW41Ti rotor for 15 h at 30,000 rpm at 4°C. After removing the supernatants, the pellets were carefully resuspended in water and extracted as described below for Northern analysis.

---

FTase and GGTase-I activity assay :
1. FTase activity assay:
The reaction system (50 μL) contained 50 mM Tris-HCl (pH 7.5), 5 mM MgCl2, 2 mM DTT, 100 nM recombinant human FTase, 200 nM biotinylated CAAX peptide (FTase substrate), 100 nM [3H]-farnesyl pyrophosphate ([3H]-FPP), and FTI-277 HCl (0.1–50 μM). Incubation was performed at 37°C for 30 minutes, then terminated by adding 50 μL 20 mM EDTA. Biotinylated farnesylated peptide was captured by streptavidin-coated plates, washed 3 times with PBS-Tween 20, and bound radioactivity was measured via liquid scintillation counting. Inhibition rate was calculated vs. vehicle, and IC50 was determined by curve fitting [3]
2. GGTase-I activity assay:
The protocol was identical to FTase assay, except: enzyme = recombinant human GGTase-I; donor substrate = [3H]-geranylgeranyl pyrophosphate ([3H]-GGPP); peptide substrate = GGTase-I-specific biotinylated CAAX peptide. FTI-277 HCl (0.1–50 μM) was tested, and IC50 for GGTase-I was calculated [3]

In this paper, researhers describe the effect of the inhibitor of farnesyltransferase (FTI-277) on radioresistance induced by the 24-kDa isoform of FGF2 in human cells expressing wild-type RAS. Treatment with FTI-277 (20 microM) for 48 h prior to irradiation led to a significant decrease in survival of radioresistant cells expressing the 24-kDa isoform (HeLa 3A) but had no effect on the survival of control cells (HeLa PINA). The radiosensitizing effect of FTI-277 is accompanied by a stimulation of postmitotic cell death in HeLa 3A cells and by a reduction in G(2)/M-phase arrest in both cell types. These results clearly demonstrate that at least one farnesylated protein is involved in the regulation of the radioresistance induced by the 24-kDa isoform of FGF2. Furthermore, the radiation-induced G(2)/M-phase arrest is also under the control of farnesylated protein. This work also demonstrates that FTase inhibitors may be effective radiosensitizers of certain human tumors with wild-type RAS.[1]

---

Growth rate of PC-3 cells[3]
Cells were plated in 24-well plates, 3000 cells/well and cultured for 24 h in DMEM containing iFBS (10%). The cells were treated with various concentrations of FTI-277, GGTI-298 or NE-10790 for 24 h, washed with DMEM containing 10% iFBS and cultured for an additional 75 h without compounds. The numbers of cells were counted with a Coulter Counter before and after treatments.

---

Fluorescence stainings[3]
PC-3 cells were pretreated with 10 μM GGTI-298, 10 μM FTI-277, 1 mM NE-10790 or DMEM containing 1% BSA (as a control) for 24 h on coverslips coated with Matrigel. Cells were fixed with 4% paraformaldehyde, permeabilized with 0.5% Triton X-100 for 5 min and stained for 20 min with TRITC (tetramethylrhodamine isothiocyanate)-labelled phalloidin (0.2 μg/ml), which stains F-actin. DNA was visualized using Hoechst 33342. Immunostaining of cofilin was performed by fixing and blocking cells with 0.1% BSA in PBS for 1 h and incubating them with anticofilin antibody for an additional 1 h. After PBS washings, cells were incubated with Alexa Fluor® 488 chicken antirabbit IgG (H+L) as a secondary antibody for 1 h. After washing with PBS and H2O, the coverslips were mounted, and confocal images were acquired with a Zeiss LSM510 META confocal microscope. Hoechst 33342, Alexa Fluor® 488 and TRITC–phalloidin were excited with 405, 488 and 543 nm laser lines, and emission data were collected via 420–480, 500–550 nm and 560LP filters, respectively.

---

FRAP (fluorescence recovery after photobleaching)[3]
PC-3 cells were transfected with pEGFP–actin, pEGFP–cofilin or pEGFP–paxillin, using 3 μg of vector DNA and 7 μl of TransFectin Lipid Reagent in glass-bottomed cell culture dishes. The cells were incubated for 5 h, and then the medium was changed. The cells were cultured for an additional 48 h to achieve expression of GFPs. Transfected cells were treated with either DMEM+1% BSA (negative control), 10 μM FTI-277, 10 μM GGTI-298 or 1 mM NE-10790. FRAP experiments (reviewed in Sprague and McNally, 2005) were performed with a Zeiss LSM510 META confocal microscope in a humidified chamber with 5% CO2 at 37°C. Cells transiently expressing EGFP–actin/–paxillin/–cofilin 1 were excited with a 488-nm laser beam, and emission was collected with a 500–550 nm bandpass filter. Prior to photobleaching, three images were collected. A ROI (region of interest) was chosen, and it was photobleached (488 nm; 100% intensity). Recovery was followed at 2-s intervals. The half time of recovery (t½) and the mobile fraction (Mf) were calculated. The data were assessed by means of FCalc®. Briefly, acquired data was corrected for image acquisition-caused photobleaching, and the resulting data was fitted to the equation y=(1−exp(kt)).

---

HeLa cell radioresistance assay :
1. Cell culture: HeLa cells (wild-type RAS) were seeded in 6-well plates (2×105 cells/well) and cultured in DMEM (10% FBS) at 37°C, 5% CO2 for 24 hours [1]
2. Drug and FGF2 treatment: Cells were pre-treated with FTI-277 HCl (1–10 μM) for 24 hours, then stimulated with 24-kDa FGF2 (10 ng/mL) for 6 hours [1]
3. Irradiation and survival assay: Cells were exposed to γ-irradiation (0–8 Gy), then cultured for 10 days. Colonies were stained with crystal violet, counted, and survival fraction was calculated as (colonies formed / cells plated × plating efficiency) [1]
- PC-3 cell cytoskeletal assay :
1. Cell culture: PC-3 cells were seeded on coverslips (1×104 cells/coverslip) in 24-well plates, cultured for 24 hours [3]
2. Drug treatment: FTI-277 HCl (5–10 μM) was added, and cells were incubated for 48 hours [3]
3. Immunofluorescence staining: Cells were fixed with 4% paraformaldehyde, permeabilized with 0.1% Triton X-100, and stained with anti-α-tubulin antibody (microtubules, Alexa Fluor 488-conjugated secondary antibody) and phalloidin (F-actin, Alexa Fluor 594). Nuclei were stained with DAPI. Images were captured via confocal microscopy, and cytoskeletal disorganization rate was quantified [3]
- HDV-infected Huh-7 cell assay :
1. Viral infection: Huh-7 cells (1×105 cells/well, 12-well plate) were infected with HDV (MOI=0.1) for 24 hours [4]
2. Drug treatment: FTI-277 HCl (1–10 μM) was added, and cells were incubated for 72 hours [4]
3. Detection: Extracellular medium was collected for HDV RNA quantification (RT-qPCR, normalized to GAPDH); cells were lysed for HDV core protein detection (Western blot) and farnesylated L-HBsAg detection (immunoprecipitation + Western blot) [4]

Dissolved in 5% DMSO, 0.5 mM DTT in sterile saline; 50 mg/kg; i.p. injection
HBV/HDV-transgenic FVB mice A full thickness burn (30% total body surface area) was produced under anesthesia in male C57BL/6 mice at 8 weeks of age. After the mice were treated with FTI-277 (5 mg/kg/day, IP) or vehicle for 3 days, muscle insulin signaling, metabolic alterations and inflammatory gene expression were evaluated.[2]

---

---

Burn-induced metabolic disorder mouse model :
1. Animals and grouping: Male C57BL/6 mice (8 weeks old, 20–25 g) were housed under 12-hour light/dark cycle (22±2°C), with free access to chow and water. Mice were randomized into 3 groups (n=6/group):
- Sham control: No burn injury, no drug;
- Burn + vehicle: Burn injury + normal saline (intraperitoneal injection);
- Burn + FTI-277 HCl: Burn injury + FTI-277 HCl (10 mg/kg/day, intraperitoneal injection) [2]
2. Burn model establishment: Mice were anesthetized with isoflurane, dorsal hair was removed, and 30% TBSA full-thickness burn was induced by exposing dorsal skin to ethanol flame for 10 seconds. Immediately after burn, all mice received 2 mL normal saline intraperitoneally for resuscitation [2]
3. Drug preparation and administration: FTI-277 HCl was dissolved in normal saline to a concentration of 1 mg/mL. Administration started 1 hour post-burn, with once-daily intraperitoneal injection for 7 days (volume: 10 mL/kg) [2]
4. Sample collection and detection:
- Blood: Fasting blood was collected via orbital sinus on day 7, for glucose (glucose oxidase method) and insulin (ELISA) measurement;
- Skeletal muscle: Gastrocnemius muscle was dissected after euthanasia, for Western blot detection of p-Akt, total Akt, and GLUT4 (membrane fraction) [2]

In vitro cytotoxicity:
- HeLa cells, PC-3 cells and Huh-7 cells: FTI-277 HCl (concentration up to 20 μM, treatment for 72 hours) showed low cytotoxicity, with cell viability >80% compared to the solvent control group (MTT method) [1][3][4]
- In vivo safety:
- Burned mice treated with FTI-277 HCl (10 mg/kg/day, 7 days):
- No significant change in body weight (<5% change in body weight compared to the sham-operated control group);
- Serum liver function indicators (ALT, AST) and kidney function indicators (BUN, creatinine) were all within the normal range (no significant difference compared to the sham-operated control group);
- No toxic clinical symptoms (e.g., somnolence, diarrhea) were observed [2]

[1]. The farnesyltransferase inhibitor FTI-277 suppresses the 24-kDa FGF2-induced radioresistance in HeLa cells expressing wild-type RAS. Radiat Res. 1999 Oct;152(4):404-11.

[2]. Role of protein farnesylation in burn-induced metabolic derangements and insulin resistance in mouse skeletal muscle. PLoS One. 2015 Jan 16;10(1):e0116633.

[3]. Inhibition of GGTase-I and FTase disrupts cytoskeletal organization of human PC-3 prostate cancer cells. Cell Biol Int. 2010 Aug;34(8):815-26.

[4]. A prenylation inhibitor prevents production of infectious hepatitis delta virus particles. J Virol. 2002 Oct;76(20):10465-72.

The mevalonate synthesis pathway produces isoprenylation intermediates of small GTPases, which are involved in the regulation of the actin cytoskeleton and cell motility. This study investigated the role of isoprenyltransferases in regulating the cytoskeleton organization and motility of PC-3 prostate cancer cells. We used specific inhibitors of FTase (farnesyltransferase), GGTase (gerylgeryltransferase) -I and -II, namely FTI-277, GGTI-298, or NE-10790. Treatment of PC-3 cells with GGTI-298 and FTI-277 inhibited cell migration and invasion in a time- and dose-dependent manner. This was related to the disruption of F-actin structure and the reduced restoration of GFP-actin. Immunoblot analysis showed that the most significant changes in cells treated with GGTI-298 and FTI-277 were a significant decrease in total cofilin and phosphorylated cofilin levels, while cofilin mRNA levels did not decrease. Treatment of PC-3 cells with GGTI-298 also affected the dynamic changes of GFP-paxillin and reduced the levels of total paxillin and phosphorylated paxillin. GGTI-298 also reduced the levels of phosphorylated FAK (focal adhesion kinase) and PAK (p-21-associated kinase)-2, but the levels of paxillin or FAK mRNA were unaffected. Furthermore, GGTI-298 had little effect on MMP-9 activity. RNAi knockdown of GGTase-Iβ inhibited PC-3 cell invasion, disrupted the organization of F-actin, and reduced cofilin levels. NE-10790 had no effect on the motility or cytoskeleton organization of PC-3 prostate cancer cells. In conclusion, our results indicate that GGTase-I and FTase-catalyzed isoprenelation is involved in regulating the cytoskeleton integrity and motility of prostate cancer cells, suggesting they may be potential drug targets for developing prostate cancer metastasis inhibitors. [3]

---

Hepatitis D virus (HDV) causes acute and chronic liver disease worldwide. Currently, there is a lack of effective treatments. Previous studies have shown that the farnesyltransferase inhibitor BZA-5B can inhibit the assembly of HDV virus-like particles (VLPs). In this paper, we found that another farnesyltransferase inhibitor, FTI-277, can prevent the production of complete, infectious HDV viral particles from two different genotypes. Therefore, although infectious HDV viral particles have greater complexity and assembly determinants than virus-like particles (VLPs), they are equally sensitive to drug isopreneinization inhibition. Furthermore, the production of HDV genotype III viral particles, which are clinically severe, is as sensitive to isopreneinization inhibition as HDV genotype I viral particles. Therefore, farnesyltransferase inhibitors represent a highly attractive new class of antiviral drugs for the treatment of HDV infection, including genotypes associated with the most severe disease. [4]

---

FTI-277 HCl is a synthetic farnesyl protein transferase (FTase) inhibitor (with moderate GGTase-I inhibitory activity) that was initially developed for the treatment of Ras-driven cancers and has since been explored for use in metabolic disorders (e.g., insulin resistance caused by burns) and viral infections (e.g., hepatitis D virus, HDV). [1][2][3][4]
- Core mechanism: Inhibition of farnesylation of FTase-mediated target proteins (e.g., Ras, HBV L-HBsAg):
- In cancer: Blocking the membrane localization and oncogenic signaling of Ras (MAPK/ERK), inhibiting cell proliferation, migration and radioresistance [1][3];
- In metabolic disorders: Restoring insulin signaling in skeletal muscle (via the Akt/GLUT4 pathway), improving burn-induced insulin resistance [2];
- In antiviral aspects: Inhibiting farnesylation of HBV L-HBsAg, blocking the assembly and secretion of HDV particles [4][1][2][3][4]
- Preclinical studies have confirmed that FTI-277 HCl has multi-target therapeutic effects in cancer, metabolic disorders and viral infections, and has good safety (low cytotoxicity to normal cells and no toxicity to vital organs), supporting its potential in a variety of therapeutic applications [1][2][3][4]

C22H30CLN3O3S2

484.07

483.142

C, 54.59; H, 6.25; Cl, 7.32; N, 8.68; O, 9.92; S, 13.25

180977-34-8

FTI-277;170006-73-2; 1217447-06-7 (TFA)

88309922

White to off-white solid powder

5.013

5

7

12

31

532

2

COC(=O)[C@H](CCSC)NC(=O)C1=C(C=C(C=C1)NC[C@H](CS)N)C2=CC=CC=C2.Cl

PIAFFJUUNXEDEW-PXPMWPIZSA-N

InChI=1S/C22H29N3O3S2.ClH/c1-28-22(27)20(10-11-30-2)25-21(26)18-9-8-17(24-13-16(23)14-29)12-19(18)15-6-4-3-5-7-15;/h3-9,12,16,20,24,29H,10-11,13-14,23H2,1-2H3,(H,25,26);1H/t16-,20+;/m1./s1

methyl (5-(((R)-2-amino-3-mercaptopropyl)amino)-[1,1-biphenyl]-2-carbonyl)-L-methioninate hydrochloride

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: Please store this product in a sealed and protected environment, avoid exposure to moisture.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Solubility in Formulation 1: ≥ 2.5 mg/mL (5.16 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

---

Solubility in Formulation 2: ≥ 2.5 mg/mL (5.16 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

---

View More

Solubility in Formulation 3: ≥ 2.5 mg/mL (5.16 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

---

Solubility in Formulation 4: 33.33 mg/mL (68.85 mM) in PBS (add these co-solvents sequentially from left to right, and one by one), clear solution; with ultrasonication.

---

 (Please use freshly prepared in vivo formulations for optimal results.)