We have observed many patients treated with levothyroxine sodium who have elevated serum thyroxine (T4) levels but appear clinically euthyroid. Such patients generally have normal serum triiodothyronine (T3) values. A retrospective review at The Johns Hopkins Hospital, Baltimore, comparing the correlation of T3 and T4 values in levothyroxine-treated patients with that in patients not so treated was carried out from 1977 to 1979. Mean free thyroxine index (FTI) value in 104 levothyroxine-treated patients was 4.70 +/- 0.2 and mean T3 value was 177 +/- 9 ng/dL. In a group of 50 hyperthyroid patients, mean FTI value was 7.26. +/- 0.5, with a mean T3 value of 389 +/- 26 ng/dL. In 71 euthyroid patients, mean FTI value was 2.36 +/- 0.1, with a T3 value of 137 +/- 3 ng/dL. Computed ratios of T3 to FTI and T3 to T4 were significantly lower in the group treated with levothyroxine than in either the hyperthyroid or euthyroid nontreated groups. Levothyroxine-treated patients with high T4 levels but normal T3 levels were clinically euthyroid. Patients not treated with levothyroxine with similarly elevated T4 levels had elevated T3 levels and were clinically hyperthyroid. It is concluded that lower relative T3 levels in levothyroxine-treated patients may explain why these patients appear clinically euthyroid despite elevated T4 values. Serum T3 determination is the procedure of choice for evaluation of levothyroxine-treated individuals. Furthermore, an elevated FTI value in such an individual does not, in itself, dictate need to reduce dosage.

Farnesyltransferase inhibitors (FTIs) have mainly been used in cancer therapy. However, more recently, investigations on these inhibitors revealed that FTIs can be used for the treatment of other diseases such as Progeria, P. falciparum resistant malaria, Trypnosomatid, etc. Hence the development of novel FTIs is an important task for the drug discovery program. Initially, numerous peptidomimetic FTIs were developed from the template of CAAX (CVIM was the first pharmacophore model used as a peptidomimetic). Later, many non-peptidomimetic FTIs have been discovered with the structural modification of the peptidomimetics. The structural analysis of those developed FTIs by various researchers suggested that the presence of a heterocycle or a polar group in place of the thiol group is required for interaction with the Zn(2+) ion. The bulky naphthyl, quinolinyl, phenyl, phenothazine, etc in this position provide better hydrophobicity to the molecules which interact with the aromatic amino acid moieties in the hydrophobic pocket. A hydrophilic region with polar groups is necessary for the polar or hydrogen bonding interactions with the amino acids or water molecules in the active site. Many FTIs have been isolated from natural products, which possessed inhibitory activity against farnesyltransferase (FTase). Among them, pepticinnamin E (9R), fusidienol (9T), gliotoxin (9V), cylindrol A (9X), etc possessed potential FTase inhibitory activities and their structural features are comparable to those of the synthetic molecules. The clinical studies progressing on FTIs showed that tipifarnib in combination with bortezomib is used for the treatment of patients with advanced acute leukemias. Successful phase I and II studies are undergoing for tipifarnib alone or in combination with other drugs/radiation for the treatment of multiple myeloma, AML, breast cancer, mantle cell lymphoma, solid tumors, non-small cell lung cancer (NSCLC), pancreatic cancer, glioblastoma, etc. Phase I pharmacokinetic (maximum tolerated dose, toxicity) and pharmacodynamic studies of AZD3409 (an orally active double prodrug) is progressing on patients with solid malignancies taking 500 mg once a day. A phase II study is undergoing on lonafarnib alone and in combination with zoledronic acid and pravastatin for the treatment of Hutchinson-Gilford Progeria syndrome (HGPS) and progeroid laminopathies. Lonafarnib therapy improved cardiovascular status of children with HGPS, by improved peripheral arterial stiffness, bone structure and audiological status in the patients. Other important FTIs such as BMS-214662, LB42908, LB42708, etc are under clinical studies for the treatment of various cancers. This review concluded that the quantitative structural analysis report with an elaborative study on the natural product compounds provides ideas for development of novel molecules for the FTase inhibitory activity. The fragment based analysis is also needed to select the substituents, which provides significant inhibitory activities and can also have good pharmacokinetic properties in the clinical studies.

Statins are used to treat hypercholesterolemia and seem to have a preventive effect against cancer through pleiotropic effects including prenylation-inhibition. So far nothing is known about the activity of statins or more specific prenylation-inhibitors in Hodgkin's lymphoma (HL). We, therefore, evaluated the anti-HL activity of simvastatin and specific prenylation-inhibitors. 2 microM Simvastatin induced caspase-related apoptosis via depletion of prenylation-substrates in several HL-cell lines. Furthermore, it effectively impaired tumor growth in a mouse model for HL. Since the prenylation-inhibitors FTI-277 and GGTI-298 were also effective against HL-cells, we conclude that statins and specific prenylation-inhibitors should be evaluated in HL patients.

OBJECTIVE

The inhibition of activated Ras combined with radiotherapy was identified as a potential method for radiosensitization.

METHODS

Immunoblotting was used to control for prenylation inhibition of the respective Ras isoforms and for changes in activity of downstream proteins. Clonogenic assays with human and rodent tumour cell lines and transfected cell lines served for the testing of radiosensitivity. Xenograft tumours were treated with farnesyl transferase inhibitors and radiation and assayed for ex vivo plating efficiency, regrowth of tumours and EF5 staining for detection of hypoxia. Concurrent treatment with L-778,123 and radiotherapy was performed in non-small cell lung cancer (NSCLC) and head and neck cancer (HNC) patients.

RESULTS

Blocking the prenylation of Ras proteins in cell lines with Ras activated by mutations or receptor signalling resulted in radiation sensitization in in vitro and in vivo. The PI3 kinase downstream pathway was identified as a contributor to Ras-mediated radiation resistance. Additionally, increased oxygenation of xenograft tumours was observed after FTI treatment. Combined treatment in a phase I study was safe and effective in NSCLC and HNC.

CONCLUSIONS

Tumour cells with activated Ras were sensitized to radiation. Unravelling the underlying mechanisms promises to lead to even more specific drugs with higher potency and safety.

Laminin-1 (LN) is expressed along the route of neural growth from spiral ganglion (SG) neurons towards the developing organ of Corti, and has been shown to enhance neurite outgrowth from SG neurons in vitro. Signal transduction pathways linking LN signaling at the cell membrane to the cell nucleus can involve a variety of signaling molecules. Data from other systems suggest the potential involvement of the small G protein Ras, and the mitogen-activated protein kinases (MAPKs) Erk and/or p38. To assess these possibilities, the length and number of processes extending from SG explants cultured on LN-coated surfaces were evaluated after treatment with the Ras inhibitor FTI-277, the p38 inhibitor SB203580 and MAPK kinase (MEK) inhibitor U0126, which operates immediately upstream of the Erk MAPK. Treatment with the Ras inhibitor at levels known to inhibit the H- and N-Ras isoforms had no effect, while FTI-277 levels known to inhibit K-Ras reduced only neurite length. Suppression of MEK resulted in a decrease of both parameters, while incubation with the p38 inhibitor had no effect. The results of this study suggest that MEK plays a central role in LN signaling in SG neurites. While K-Ras signaling may participate in MEK-dependent increases in neurite length, the MEK-dependent increase in neurite number appears to be activated by a different intracellular pathway.

Advanced head and neck squamous cell cancer (HNSCC) is currently treated with taxane-based chemotherapy. We have previously shown that docetaxel (DTX) induces a ras-dependent survival signal that can be antagonized by farnesyl transferase inhibitors (FTI) such as tipifarnib (TIP). Here we show that the synergistic TIP/DTX combination determines synergistic apoptotic conditions but, at the same time, it modulates the expression of the components of the multichaperone complex that is, in turn, involved in the regulation of the stability of members of the ras-mediated pathway. Therefore, we have stably transfected HNSCC KB and Hep-2 cells with a plasmid encoding for HSP90. The expression of the protein was increased in both transfected cell lines but its activation status was increased in Hep-2 clones and decreased in KB clones. On the basis of these results, we have treated both parental and HSP90-transfected cells with a HSP90 inhibitor geldanamycin (GA). We have found that the antiproliferative activity of GA is dependent upon the activation status of HSP90 and that it is strongly synergistic when added in combination with TIP but not with DTX in cells overexpressing HSP90 and even more in cells with increased HSP90 activity. These data were paralleled by the decreased expression and activity of the components belonging to the ras→mediated signal transduction pathway. The present results suggest that multichaperone complex activation could be a resistance mechanism to the anti-proliferative and apoptotic effects induced by TIP and that the combination of FTIs such as TIP with GA could be a suitable therapeutic strategy in the treatment of HSP90-overexpressing HNSCC.

Hutchinson-Gilford progeria syndrome (HGPS) is a rare and fatal premature ageing disease in children. HGPS is one of several progeroid syndromes caused by mutations in the LMNA gene encoding the nuclear structural proteins lamins A and C. In classic HGPS the mutation G608G leads to the formation of a toxic lamin A protein called progerin. During post-translational processing progerin remains farnesylated owing to the mutation interfering with a step whereby the farnesyl moiety is removed by the enzyme ZMPSTE24. Permanent farnesylation of progerin is thought to be responsible for the proteins toxicity. Farnesyl is generated through the mevalonate pathway and three drugs that interfere with this pathway and hence the farnesylation of proteins have been administered to HGPS children in clinical trials. These are a farnesyltransferase inhibitor (FTI), statin and a bisphosphonate. Further experimental studies have revealed that other drugs such as N-acetyl cysteine, rapamycin and IGF-1 may be of use in treating HGPS through other pathways. We have shown previously that FTIs restore chromosome positioning in interphase HGPS nuclei. Mis-localisation of chromosomes could affect the cells ability to regulate proper genome function. Using nine different drug treatments representing drug regimes in the clinic we have shown that combinatorial treatments containing FTIs are most effective in restoring specific chromosome positioning towards the nuclear periphery and in tethering telomeres to the nucleoskeleton. On the other hand, rapamycin was found to be detrimental to telomere tethering, it was, nonetheless, the most effective at inducing DNA damage repair, as revealed by COMET analyses.

Hutchinson-Gilford progeria syndrome (HGPS) is a rare genetic condition associated with mutations in the LMNA gene. This disease recapitulates some aspects of normal aging, such as hair loss, thin skin, joint stiffness, and atherosclerosis. The latter leads to heart attack or stroke that causes death at an average age of 14.6 years in children with HGPS. The typical LMNA mutation results in the production of a truncated prelamin A protein, progerin, that remains permanently farnesylated and abnormally associated with the nuclear envelope. Farnesyltransferase inhibitors (FTIs) reverse nuclear structure abnormalities that are characteristic of HGPS cells. The first clinical trial using the FTI, Ionafarnib, demonstrated some improvements in HGPS children and, in particular, showed a decrease in arterial stiffness. Recently, we reported that sulforaphane, an antioxidant derived from cruciferous vegetables, efficiently stimulates autophagy and enhances progerin clearance in HGPS fibroblasts. In the present study, we investigated the effect of combined lonafarnib and sulforaphane treartment in HGPS fibroblast cultures. We report that co-administration of both drugs exerts a synergistic and additive positive effect on autophagy activity but was cytotoxic to HGPS cells. In contrast, intermittent treatment with lonafarnib followed by sulforaphane separately and in repeated cycles rescued the HGPS cellular phenotype. We propose that intermittent treatment with FTI and SFN separately might be a promising therapeutic avenue for children with HGPS.

We studied interrelationships between maternal and neonatal thyroid function, TSH receptor binding inhibiting immunoglobulins (TBII), and dose of thionamide antithyroid drugs in 44 women with active Graves' disease presenting during 46 pregnancies, and their 48 infants. The women were treated with propylthiouracil (PTU) or carbimazole (CBZ). In 30 pregnancies (30 infants) treatment was withdrawn from 3 to 18 weeks before delivery (Group A). Drug treatment (PTU, n = 10, dose 50-400 mg/day or CBZ, n = 6, dose 5-45 mg/day) was continued throughout pregnancy and delivery in 16 pregnancies producing 18 infants (Group B). The maternal TBII at delivery was well correlated with maternal free thyroxine index (FTI) averaged over the third trimester (r = 0.603, P less than 0.001) and umbilical venous serum TBII (r = 0.940, P less than 0.001). Neonatal FTI was independently related to umbilical vein TBII (t = 2.29, P = 0.03) and maternal dose of antithyroid drug (t = -2.21, P = 0.03). Neonatal thyrotoxicosis was seen in all four infants (8% of births) of women whose TBII levels at delivery exceeded 70%. No child was born with a subnormal FTI but 7/18 infants in group B had raised TSH at birth. This was more likely to occur (P = 0.05) if maternal TBII was less than 30% (6/10) than if maternal TBII was greater than 30% (1/8). Four Group B women with FTI in the lower half of the reference range delivered infants with raised TSH compared with 3/14 (21%) women whose FTI was in the upper half of the reference range or above (P = 0.05). In pregnant women with active Graves' disease TBII levels reflect stimulatory TSH receptor antibody activity. TBII measurements are of use in the prediction of neonatal thyrotoxicosis and impaired neonatal thyroid function in infants of women treated with antithyroid drugs.

Thyroidectomy (TX) is no longer the preferred choice for the therapy of hyperthyroid Graves' disease but is an alternative in patients who are noncompliant with or have reactions to antithyroid drugs, have moderate to severe ophthalmopathy, have large goiters, or who refuse (131)I therapy and/or long-term antithyroid drug therapy. Seventeen clinically and biochemically severely thyrotoxic patients (16 female, mean age of 35 yr), all but one with large goiters, underwent TX after rapid preparation. The potent inhibitors of the deiodination of T(4) to T(3), iopanoic acid (IOP) (500 mg twice a day) and dexamethasone (DEX) (1 mg twice a day), were given with propylthiouracil or methimazole, when possible, and beta-blockers. Thyroid function tests were obtained before treatment and at TX. All patients were thyrotoxic (mean +/- SE: T(4), 21.6 +/- 1.2 micro g/dl; free T(4) index (FTI), 10.3 +/- 0.8; total T(3), 510 +/- 48 ng/dl). IOP and DEX rapidly lowered T(3) values (P < 0.0001; total T(3), 147 +/- 13 ng/dl) with a smaller but significant (P < 0.05) decrease in T(4)/FTI (T(4), 17.9 +/- 1.3 micro g/dl; FTI, 7.9 +/- 0.6). All patients were clinically euthyroid before surgery. None developed hypoparathyroidism, laryngeal nerve damage, or worsening of ophthalmopathy after surgery. The restoration of hyperthyroid Graves' disease to euthyroidism is rapidly accomplished with IOP and DEX, beta-blockers, and, when possible, antithyroid drugs. This is especially relevant in noncompliant patients with large goiters.

Eight children with cystinosis (3 with renal transplants, 2 on maintenance haemodialysis, 2 with chronic renal failure, and one with normal renal function) were studied for evidence of hypothyroidism, and compared with a control group of children with chronic renal failure due to other causes. Abnormal thyroid function was present in all the cystinotic patients: thyroxine (T4) low in 1, free thyroxine index (FTI) low in 2, thyroid-stimulating hormone (TSH) raised in 6; all had a supranormal TSH response to thyrotrophin-releasing hormone (TRH) stimulation, indicating impaired thyroid reserve compared with patients in the control group who had a depressed or normal TSH response. Increased growth velocity with thyroid supplementation occurred in only 2 patients, and the onset of puberty may have contributed to this improvement. Hypothyroidism is a common finding in cystinosis, and it is suggested that thyroxine treatment be started when the TSH concentration becomes raised.

BACKGROUND

Farnesyltransferase inhibitors (FTIs) are anticancer agents developed to inhibit Ras oncoprotein activities. FTIs of different chemical structure act via a conserved mechanism in eukaryotic cells. They have low toxicity and are active on a wide range of tumors in cellular and animal models, independently of the Ras activation state. Their ultimate mechanism of action, however, remains undetermined. FTase has hundred of substrates in human cells, many of which play a pivotal role in either tumorigenesis or in pro-survival pathways. This lack of knowledge probably accounts for the failure of FTIs at clinical stage III for most of the malignancies treated, with the notable exception of haematological malignancies. Understanding which cellular pathways are the ultimate targets of FTIs in different tumor types and the basis of FTI resistance is required to improve the efficacy of FTIs in cancer treatment.

RESULTS

Here we used a yeast-based cellular assay to define the transcriptional changes consequent to FTI peptidomimetic administration in conditions that do not substantially change Ras membrane/cytosol distribution. Yeast and cancer cell lines were used to validate the results of the network analysis. The transcriptome of yeast cells treated with FTase inhibitor I was compared with that of untreated cells and with an isogenic strain genetically inhibited for FTase activity (Deltaram1). Cells treated with GGTI-298 were analyzed in a parallel study to validate the specificity of the FTI response. Network analysis, based on gene ontology criteria, identified a cell cycle gene cluster up-regulated by FTI treatment that has the Aurora A kinase IPL1 and the checkpoint protein MAD2 as hubs. Moreover, TORC1-S6K-downstream effectors were found to be down-regulated in yeast and mammalian FTI-treated cells. Notably only FTIs, but not genetic inhibition of FTase, elicited up-regulation of ABC/transporters.

CONCLUSIONS

This work provides a view of how FTIs globally affect cell activity. It suggests that the chromosome segregation machinery and Aurora A association with the kinetochore as well as TORC1-S6K downstream effectors are among the ultimate targets affected by the transcriptional deregulation caused by FTI peptidomimetics. Moreover, it stresses the importance of monitoring the MDR response in patients treated with FTIs.

Neoplastic transformation sensitizes many cells to apoptosis. This phenomenon may underlie the therapeutic benefit of many anticancer drugs, but its molecular basis is poorly understood. We have used a selective and potent farnesyltransferase inhibitor (FTI) to probe a mechanism of apoptosis that is peculiarly linked to neoplastic transformation. While nontoxic to untransformed mouse cells, FTI triggers a massive RhoB-dependent, p53-independent apoptosis in mouse cells that are neoplastically transformed. Here we offer evidence that the BAR adapter-encoding tumor suppressor gene Bin1 is required for this transformation-selective death program. Targeted deletion of Bin1 in primary mouse embyro fibroblasts (MEFs) transformed by E1A+Ras did not affect FTI-induced reversion, actin fiber formation, or growth inhibition, but it abolished FTI-induced apoptosis. The previously defined requirement for RhoB in these effects suggests that Bin1 adapter proteins act downstream or in parallel to RhoB in cell death signaling. The death defect in Bin1 null cells was significant insofar as it abolished FTI efficacy in tumor xenograft assays. p53 deletion did not phenocopy the effects of Bin1 deletion. However, MEFs transformed by SV40 large T antigen+Ras were also resistant to apoptosis by FTI, consistent with other evidence that large T inhibits Bin1-dependent cell death by a p53-independent mechanism. Taken together, the results define a function for Bin1 in apoptosis that is conditional on transformation stress. This study advances understanding of the functions of BAR adapter proteins, which are poorly understood, by revealing genetic interactions with an Rho small GTPase that functions in stress signaling. The frequent losses of Bin1 expression that occur in human breast and prostate cancers may promote tumor progression and limit susceptibility to FTI or other therapeutic agents that exploit the heightened sensitivity of neoplastic cells to apoptosis.

The effects of farnesyl:protein transferase inhibitors (FTIs) were evaluated against hormone-dependent and hormone-independent prostate cancer cell lines harboring mutant and wild type Ras. The combinations of the FTI with hormones and chemotherapy were explored. The effect of FTI on the growth of human prostate cancer lines was examined under anchorage-dependent and -independent conditions. Changes in Ras processing and cellular localization were examined by immunoblotting and immunocytochemistry. Hormone-dependent (LNCaP) and -independent (TSU-Pr1, PC3 and DU145) human prostate cancer cell lines were growth-inhibited by the FTI L-744,832 at concentrations ranging from 100 nM to 20 &mgr;M. The inhibition was accompanied by loss of protein farnesylation and with the accumulation of Ha-Ras as its unprocessed, cytosolic form. No effect on N- and Ki-Ras processing was observed. The transformed phenotype of TSU-Pr1 cells, which possess a Ha-Ras Gly-12-Val activating mutation, reverted following FTI treatment. Enhanced antitumor effects were observed when the FTI was combined with gamma-radiation, etoposide, doxorubicin, cisplatin, estramustine and the antihormone bicalutamide. In particular, the combination of taxol and FTI was synergistic for DU145 cells, a cell line that is only marginally sensitive to the FTI alone. The sensitivity of human prostate cancer cell lines to the FTI is independent of the presence of mutations of tumor suppressors, cell cycle regulators and of the activation of a variety of oncogenes, including Ras. A cell line expressing mutated Ha-Ras is particularly sensitive. Enhanced antitumor effects were observed with an anti-androgen, gamma-irradiation, and several chemotherapeutic agents. These findings support the clinical evaluation of FTIs alone or in combination as treatment for this disease. Prostate Cancer and Prostatic Diseases (2001) 4, 33-43

The relative loss of peak force from electrical stimulation protocols has provided inconsistent results when used to compare muscle fatigability between young and old adults. In addition to the effect of task on these comparisons, age-related alterations in the development and relaxation of force are possible factors that have not been considered. The purposes of this study were to compare the fatigability of the quadriceps of young (26.7 +/- 1.0 years) and old men (78.3 +/- 1.3 years), as assessed by changes in peak force, force time integral (FTI), and half-relaxation time (HRT), during intermittent electrical stimulation protocols, and to determine whether manipulation of the activation frequency affected the comparisons. Fatigue was caused by constant-frequency (CF), and catchlike-inducing (CI) train protocols, both of which consisted of intermittent trains (6 pulses on: 650 ms off) of stimulation. After each protocol, the force-generating capacity of the fatigued muscle was assessed with three trains of stimuli: a CF train, a CI train and a 1-s 50-HZ train. There was no effect of age on the loss of peak force or the development of low-frequency fatigue induced by either protocol. Conversely, irrespective of the protocol, the FTI was better maintained by approximately 9% in the old than young men. Because peak force did not differ between groups during fatigue, it is likely that the FTI was preserved by the exacerbated slowing of HRT in the quadriceps of the old men. The results confirm an apparent paradox between muscle fatigue and stimulation with CI trains: a single CI train produces greater force than a CF train in a fatigued muscle, but there is greater fatigue induced by repetitive CI than CF train stimulation. Old age did not affect this fatigue paradox.

Farnesyltransferase inhibitors (FTIs) represent a new class of anticancer agents that specifically target post-translational farnesylation of various proteins that mediate several cellular processes such as signal transduction, growth, differentiation, angiogenesis and apoptosis. These compounds were originally designed to block oncogenic RAS-induced tumor growth by impeding RAS localization to the membrane, but it is now evident that FTIs also affect processing of several other proteins. The need for novel therapies in myeloid leukemia is underscored by the high rate of treatment failure due to high incidences of relapse- and treatment-related toxicities. As RAS deregulation is important in the pathogenesis of myeloid leukemias, targeting of RAS signaling may provide a new therapeutic strategy. Several FTIs (eg BMS-214662, L-778,123, R-115777 and SCH66336) have entered phase I and phase II clinical trials in myeloid leukemias. This review discusses recent clinical results, potential combination therapies, mechanisms of resistance and the clinical challenges of toxicities associated with prenylation inhibitors.

New targets for drug discovery have been identified rapidly as a result of the many recent and rapid advances in the understanding of signal transduction pathways that contribute to oncogenesis. In particular, oncogenic Ras proteins have been seen as an important target for novel anti-cancer drugs. Since the decade-old identification and cloning of farnesyltransferase (FTase), a critical enzyme that post-translationally modifies Ras and other farnesylated proteins, FTase inhibitors (FTIs) have been under intense investigation designed to bring them to clinical practice for cancer therapy. FTIs can inhibit the growth of tumour cells in culture and in animal models, and are now in clinical trials. Interestingly, their mechanism of action is not as simple as originally envisioned, and Ras is probably not the most important farnesylated protein whose modification is inhibited as a result of FTI treatment. Although K-Ras can escape inhibition of processing by FTIs, tumours with oncogenically mutated K-Ras proteins can still be inhibited by FTI treatment. Indeed, Ras mutation status does not correlate with FTI sensitivity or resistance. Instead, it now appears likely that inhibition of the processing of other farnesylated proteins such as RhoB and the centromere-binding proteins CENP-E and CENP-F can explain the ability of FTIs to cause cell cycle arrest and apoptosis in preclinical studies, and even to cause regression in animal tumour models. Preclinical studies suggest the likelihood that FTIs will be useful in combination therapies with conventional treatment modalities including cytotoxics (especially paclitaxel) and radiation. Phase I combination trials are underway, and early phase II/III trials using FTIs as monotherapy are open for patients with a wide variety of cancers. Early preclinical results also suggest the possibility of using FTIs as chemopreventive agents. Studies to be completed over the next 2 or 3 years should define the appropriate patient populations, administration and scheduling necessary to optimise the use of these novel anticancer agents.

Farnesylation of Ras, a protooncogene that is frequently mutated in a number of malignancies, is critical for its biologic function. This observation has led to the development of several agents that inhibit farnesyltransferase, known as farnesyltransferase inhibitors (FTIs). The antiproliferative and antitumor effects of these agents have been demonstrated in preclinical and clinical studies. Interestingly, FTI activity does not necessarily rely on ras mutational status, indicating that Ras is not the only FTI target. Clinical data suggest that FTIs, alone and in combination with other agents, have antitumor activity. Further study is needed to determine the precise mechanism of FTI antitumor activity as well as how and where FTIs will be best used clinically.

Since farnesylation by farnesyltransferase (FTase) is the first obligatory step in the signaling transduction pathway of ras p21, FTase has been the target of new anticancer treatment modalities. Famesyl transferase inhibitors (FTIs), a novel class of antitumor drugs that blocks the oncogenic activity of ras, were first developed as therapy for ras-mutated human tumors. FTIs are also capable of inhibiting tumors without ras mutations, while different mechanisms of cell growth inhibition by FTI have been proposed. In cell culture and in animal models, FTIs have been shown to be potent inhibitors of cancer cell growth. We showed that manumycin, a farnesyl pyrophosphate competitive inhibitor, inhibits ovarian and mesothelioma cancer cell growth. To examine the molecular changes after exposure to manumycin, total proteins from treated and untreated 2774 cell line were extracted and separated by two dimensional gel electrophoresis (2-DE) and detected by colloidal coomassie blue staining. The 2-DE was found reliable for comparison of protein profiles before and after manumycin treatment. Two protein spots (spot 1 and 2) appeared after manumycin treatment. Generated peptide peaks were matched by database query (prowl.rockefeller.edu/cgi-bin/ProFound) to a heat shock protein (HSP) and a modified HSP, both with MW 70 KD. The expression status of HSP 70 was confirmed by Western blot and HSP 70 ELISA using an antibody against HSP 70. The expression of HSP70 increased with the length of exposure to, and the dose of manumycin as demonstrated by ELISA. Increase in HSP70 expression was also observed by Western blot after a 48-hour treatment with manumycin in ovarian cancer cell line OVCAR3 and three other cell cultures derived from samples of patients diagnosed with ovarian cancer and mesothelioma. Our study is the first report demonstrating an up-regulation of HSP 70 in ovarian cancer cell lines and mesothelioma cell cultures after treatment with the FTI, manumycin. This up-regulation of HSP 70 may be a cellular mechanism of cell self-protection against the apoptotic process and cell death, and it may enhance resistance and account for the altered sensitivity of certain cancers to FTIs agents. HSPs may therefore be an important molecular target for drug intervention strategies.

In insect walking systems, nonspiking interneurons (NSIs) play an important role in the control of posture and movement. As such NSIs are known to contribute to state-dependent modifications in processing of proprioceptive signals from the legs. For example, NSIs process a flexion of the femur-tibia (FTi) joint signaled by the femoral chordotonal organ (fCO) such that the stance phase motor output is reinforced in the active locomotor system. This phenomenon representing a reflex reversal is the first part of the "active reaction" (AR) and was hypothesized to functionally represent a major control feature by which sensory feedback supports stance generation. As NSIs are known to contribute to the AR, the question arises, whether they serve similar functions during stepping and whether the AR is generally part of the control system for walking. We studied these issues in vivo, in a single leg preparation of Carausius morosus with the leg kinematics being confined to changes in one plane, along the coxa-trochanteral and the FTi-joint. Following kinematic analysis, identified NSIs (E1-E8, I1, I2, and I4) were recorded intracellularly during single leg stepping at different velocities. We detected clear similarities between the activity pattern of NSIs during single leg stepping and their responses to fCO-stimulation during the generation of the AR. This strongly supports the notion that the motor output generated during the AR reflects part of the control regime for stepping. Furthermore, our experiments revealed that alterations in stepping velocity result from modifications in the activity of the premotor NSIs involved in stance phase generation.

BACKGROUND

One of the most common endocrine problems in major beta-thalassemia is hypothyroidism (HT). The aim of this study was to evaluate thyroid function status in major β-thalassemia patients older than 10 years old.

METHODS

This cross sectional study was carried out on thalassemia major patients registered on Thalassemia Center of Amirkola Children Hospital in Babol. A questionnaire was filled out by the patients to evaluate the demographic information, quality of their last transfusions and chelation therapy. Growth parameters were evaluated. We assessed serum T4, TSH, T3RU and FTI in all patients and those with hypothyroidism, anti-thyroglobulin and anti-thyroid proxidase antibodies were checked Results: One hundred-thirty patients (56 males and 74 females) were enrolled in this study. The mean age was 20.95±7.8 years. Short stature was seen in 41(31.3%) patients. In 53(40.8%) patients, weight was under normal range. HT was found in 19 patients (14.6%); 2 primary overt HT, 3 secondary HT and 14 subclinical HT were detected. No patient with HT had significant serum level of anti-thyroid antibodies. Correlation between HT and serum ferritin level was not significant (p=0.584) but it was significant for HT and short statures (p=0.002), also regular transfusion and chelation therapy were correlated with ferritin level.

CONCLUSIONS

High prevalence of HT among thalassemic patients signifies the importance of regular screening for evaluation of endocrine function in these patients; especially when short stature is present.

Our purpose was to evaluate effects of cadence manipulation on plantar loading during running. Participants (n=38) ran on a treadmill at their preferred speed in 3 conditions: preferred, 5% increased, and 5% decreased while measured using in-shoe sensors. Data (contact time [CT], peak force [PF], force time integral [FTI], pressure time integral [PTI] and peak pressure [PP]) were recorded for 30 right footfalls. Multivariate analysis was performed to detect differences in loading between cadences in the total foot and 4 plantar regions. Differences in plantar loading occurred between cadence conditions. Total foot CT and PF were lower with a faster cadence, but no total foot PP differences were observed. Faster cadence reduced CT, pressure and force variables in both the heel and metatarsal regions. Increasing cadence did not elevate metatarsal loads; rather, total foot and all regions were reduced when healthy runners increased their cadence. If a 5% increase in cadence from preferred were maintained over each mile run the impulse at the heel would be reduced by an estimated 565 body weights*s (BW*s) and the metatarsals 140-170 BW*s per mile run despite the increased steps taken. Increasing cadence may benefit overuse injuries associated with elevated plantar loading.

High-frequency electrical stimulation (HFES) leads to muscle hypertrophy, and attention has been drawn to the high forces involved. However, both mechanical and metabolic stresses occur simultaneously, and both stimuli influence signaling cascades related to protein synthesis. This study aimed to identify the immediate signaling correlates of contraction-induced force and metabolic stresses under the hypothesis that HFES induces growth-related signaling through mechanical stimulation. Force-time integral (FTI) signaling in mouse tibialis anterior muscle was examined by separately manipulating the time of contraction to emphasize the metabolic aspect or the force of contraction to emphasize the mechanical aspect. When FTI was manipulated by changing the total time of activation, phosphorylation of p54 JNK, ERK and p70S6k(T421/S424) was independent of FTI, while phosphorylation of acetyl-CoA carboxylase and p38 correlated with FTI. When FTI was manipulated by changing the force of contraction, p54 JNK, ERK and p70S6k(T421/S424) were again independent of FTI, while phosphorylation of p38 and FAK correlated with FTI. Factor analysis identified a p38-mTOR signaling module that correlated with FTI in both experiments. The consistent link among p38, mTOR and FTI suggests that they form a connected signaling module sensitive to the mechanical aspects of FTI, separate from markers of metabolic load.

Farnesyltransferase inhibitors (FTIs) are a new class of biologically active anticancer drugs. The exact anti-tumorigenic mechanism is currently unknown. FTIs inhibit farnesylation of a wide range of target proteins. In preclinical models, tipifarnib (R115777, Zarnestra(R)), a non-peptidomimetic competitive FTI, showed great potency against leukemic cells. Although it has recently demonstrated clinical responses in adults with refractory and relapsed acute myeloid leukemia (AML), and in older adults with newly diagnosed poor-risk AML, its activity was far less than anticipated. However, it appears that tipifarnib as a single agent may be important in selected groups of patients. Much remains to be learned to optimize such therapy in patients with AML. To this end, trials that combine tipifarnib with cytotoxics are ongoing.