Farnesylated RhoB inhibits radiation-induced mitotic cell death and controls radiation-induced centrosome overduplication

Our previous results demonstrated that expressing the GTPase ras homolog gene family, member B (RhoB) in radiosensitive NIH3T3 cells increases their survival following 2 Gy irradiation (SF2). We have first demonstrated here that RhoB expression inhibits radiation-induced mitotic cell death. RhoB is present in both a farnesylated and a geranylgeranylated form in vivo. By expressing RhoB mutants encoding for farnesylated (RhoB-F cells), geranylgeranylated or the CAAX deleted form of RhoB, we have then shown that only RhoB-F expression was able to increase the SF2 value by reducing the sensitivity of these cells to radiation-induced mitotic cell death. Moreover, RhoB-F cells showed an increased G2 arrest and an inhibition of centrosome overduplication following irradiation mediated by the Rho-kinase, strongly suggesting that RhoB-F may control centrosome overduplication during the G2 arrest after irradiation. Overall, our results for the first time clearly implicate farnesylated RhoB as a crucial protein in mediating cellular resistance to radiation-induced nonapoptotic cell death.

Geranylgeranyl transferase inhibition stimulates antimelanoma immune response through MHC class I and costimulatory molecule expression

Defective antitumor immune responses are frequent consequences of defects in the expression of major histocompatibility complex (MHC) class I and costimulatory molecules. We demonstrated that statins, inhibitors of HMGCoA reductase, enhance mIFN-gamma induced expression of MHC class I antigens on murine B16F10 melanoma. GGTI-298, a geranylgeranyl transferase I inhibitor, but not FTI-277, a farnesyl transferase inhibitor, mimics this effect of statins. This effect is related to peptide transporter protein TAP1 up-regulation. Simultaneously, GGTI-298 induces the expression of CD80 and CD86 costimulatory molecules. C3 exoenzyme, which selectively inactivates Rho proteins, phenocopies the effects of GGTI-298, indicating a role for Rho proteins in these events. Furthermore, the treatment of B16F10 cells with GGTI-298 or C3 exoenzyme associated with mIFN-gamma induces in vivo tumor growth slowing down in immunocompetent but not in nu/nu syngeneic mice. Both in vivo injections and in vitro restimulation of splenocytes with GGTI-298- and mIFN-gamma-treated B16F10 cells induces an enhancement of specific CD8 T lymphocytes labeled by TRP-2/H-2K(b) tetramers. Finally, these effects are not limited to mouse models since they were also reproduced in two human melanoma cell lines. These observations indicate that protein geranylgeranylation as well as Rho protein are critical for costimulatory and IFN-gamma-dependent MHC class I molecule expression in melanoma.

Chemical-Based Translational Induction of Luciferase Expression: An Efficient Tool for in Vivo Screening of Protein Farnesylation Inhibitors

We describe the development of a cell system for in vivo screening of inhibitors of the mevalonate pathway. To this aim, we have constructed a bicistronic mRNA, transcribed from a constitutive cytomegalovirus promoter, containing the Renilla reniformis luciferase RNA open reading frame sequence as first cistron and the Firefly luciferase RNA sequence as a second cistron. The intercistronic space is made of the R17 binding sequence of the bacteriophage R17 protein. A chimeric protein able to bind to a specific sequence in the hairpin and to induce internal ribosome entry in the RNA switches on translation of the second cistron. This chimeric protein is made up of the bacteriophage RNA binding domain (R17) fused to the ribosome recruitment core of the eIF-4G1 eukaryotic translation initiation factor and to the CAAX box of H-Ras addressing the protein to the plasma membrane where it is not efficient. Internal ribosome entry upstream of the Firefly cistron is therefore under the dependence of the mevalonate pathway inhibitors. Indeed, products that are able to inhibit protein farnesylation rescue the cytoplasmic location of the R17-eIF-4G-CAAX protein, which once more becomes a translation factor for the expression of the second cistron. To exemplify the system, the present work checks the ability of various antiestrogens to interfere with the mevalonate pathway. It seems that pure antiestrogen, able to selectively bind the estrogen receptor, is unable to switch on the second Firefly cistron although selective antiestrogen-binding-site ligands are able to do so.

Développement des inhibiteurs de farnésyl transférase comme agents anticancéreux

Ras proteins belong to the monomeric GTPases familly. They control cell growth, differentiation, proliferation, and survival. Ras mutations are frequently found in human cancers and play a fundamental role in tumorigenesis. Ras requires localization to the plasma membrane to exert its oncogenic effects. This subcelllular localization is dependent of protein farnesylation which is a post translational modification catalysed by the farnesyl transferase enzyme. Farnesyl transferase Inhibitors (FTI) were then designed ten to twelve years ago to inhibit ras processing and consequently the growth of ras mutated tumor. Preclinical data show that FTIs inhibit cell proliferation and survival in vitro and in vivo of a wide range of cancer cell lines, many of which contain wild type ras suggesting that mutated Ras is not the only target of the FTIs effects. Four FTIs went then through clinical trials and three of then are still developed in the clinic. Phase I et II clinical trials confirmed a relevant antitumor activity and a low toxicity. Phase III clinical trials are currently undergoing for both solid and hematologic tumors. The expected results should allow to define the position of FTIs as anticancer drugs, particularly in combination with conventional chemotherapy, hormone therapy, radiotherapy or any other new targeted compound.

Purified donor NK-lymphocyte infusion to consolidate engraftment after haploidentical stem cell transplantation

This pilot study tested feasibility of natural killer cell purification and infusion (NK-DLI) in patients after haploidentical hematopoietic stem cell transplantation (HSCT). The aim was to obtain >or=1.0 x 10(7)/kg CD56+/CD3- NK cells and <1.0 x 10(5)/kg CD3+ T cells. Mononuclear cells were collected by 10 l leukapheresis. A two-step ex vivo procedure was used to purify NK cells, using an immunomagnetic T-cell depletion, followed by NK-cell enrichment. Five patients with high-risk myeloid malignancies were included, presenting 3-12 months after a haploidentical HSCT with mixed chimerism (3), impending graft failure (1) or early relapse (1). The purified product contained a median of 1.61 x 10(7)/kg (range 0.21-2.2) NK cells and 0.29 x 10(5)/kg (0.11-1.1) T cells. A purity of NK cells of 97% (78-99), a recovery of 35.5% (13-75), and a T-cell depletion of 3.55 log (2.9-4.5) was achieved. Infusions were well tolerated and none of the patients developed graft-versus-host disease. We observed an increase in donor chimerism in 2/5, stable mixed chimerism, decreasing chimerism and relapse of AML in one patient each. Selection of NK-DLI is technically feasible. NK cells are well tolerated when used as adoptive immunotherapy in recipients of haploidentical HSCT.

Differences between graft product and donor side effects following bone marrow or stem cell donation

We report graft product stem cell yields and donor safety results of a randomized multicenter study comparing allogeneic peripheral blood stem cell (PBSC) PBSC transplantation with BM transplantation. Matched HLA-identical sibling donors (n=329) were randomized to filgrastim-mobilized PBSC or bone marrow (BM) donation groups. Median yields per kg recipient weight of CD34(+) cells, T cells, and natural killer (NK) cells, respectively, were approximately two-fold, eight-fold, and greater than eight-fold in the PBSC group than in the BM group (CD34(+) cells, 5.8 x 10(6)/kg vs 2.7 x 10(6)/kg; T cells, 300.1 x 10(6)/kg vs 35.7 x 10(6)/kg; NK cells, 28.2 x 10(6)/kg vs 3.6 x 10(6)/kg; P<0.001 for each). In connection with the cell collection procedures, PBSC donors spent a shorter median time in hospital than BM donors (0 vs 2 days; median difference -2 days, 95% CI -2 to 2) and had fewer median days of restricted activity (2 vs 6 days; median difference -3 days, 95% CI -4 to 2). Overall, 65% of PBSC donors and 57% of BM donors reported at least one adverse event (AE), most of which were transient, mild-moderate in severity, and without clinical sequelae. PBSC donors experienced predominantly filgrastim-related AEs, while BM donors experienced predominantly harvest-related AEs.

Kyste synovial articulaire postérieur lombaire révélé par un syndrome pluriradiculaire : à propos de deux cas

INTRODUCTION

Multiradicular nerve root compression, and long lasting radicular syndrome occur very often. They happen particularly on degenerative spine. Huge synovial cyst of the zygapophyseal joints may account for it, expand in the epidural area and cause radicular syndrome.

EXEGESIS

Two cases of huge synovial cysts spreading into the spinal channel are reported here. Diagnostic and therapeutic modalities are discussed. On degenerative spine, facet joints osteoarthritis may result in synovial cysts. Physical examination findings are radicular syndrome.

CONCLUSION

Huge synovial cysts may result in multiple nerve root compression syndrome, as reported in our two cases. Typically, there's no history of preceding trauma and symptoms appear progressively. Magnetic resonance imaging of the spine shows an intra-spinal round mass with typical signal intensity and capsular formation. Treatment consists either in facet joint steroid injection performed with radiologic guidance or in surgical excision.

Haematogenous brain abscess complicating a case of Austrian syndrome

Austrian syndrome includes pneumococcal endocarditis, meningitis and rupture of the aortic valve. This study reports a case with a haematogenous brain abscess. Physicians should be aware of the risk factors and dramatic evolution of this rare disease, to avoid delays in diagnosis, and to prevent embolic complications and rupture of the aortic valve.

[Pancytopenia after viral infection in St. n. malignant lymphoma]

Bei einer 44-jährigen Patientin wird eine Panzytopenie festgestellt, nachdem sie vor Jahren wegen eines malignen Lymphoms intensiv behandelt worden war. Die Abklärungen führten zu einem sekundären Myelodysplastischen Syndrom.

High stem cell dose will not compensate for T cell depletion in allogeneic non-myeloablative stem cell transplantation

The best strategies for non-myeloablative stem cell transplants (NST) are not known. We hypothesized that a high stem cell dose and post-transplant donor lymphocyte infusions (DLI) in a T cell-depleted NST setting may result in stable engraftment without severe GvHD. We used conditioning with 200 mg/kg cyclophosphamide, and ATG, a high peripheral stem cell dose of >10 x 10(6) CD34(+) cells/kg, T cell-depleted to <1 x 10(5) CD3(+) cells/kg followed by incremental DLI. Ten patients, 53 (42-61) years of age with hematological malignancy (CML in 3, MDS in 2, myeloma in 3 and CLL in 2) were included. All patients achieved initial engraftment, at a median 13.5 (10-20) days. Three patients achieved complete chimerism, four achieved a complete hematologic remission. In seven patients the graft ultimately failed. Acute GvHD grade II was seen in three patients after DLI. At a median follow-up of 28 months (range 15-35), eight patients are alive, none died of treatment-related complications. NST with T cell depletion to prevent GVHD results in a high graft failure rate. High stem cell dose (> or =10 x 10(6) CD34(+)cells/kg) and post-transplant DLI will not compensate for the lack of T cells to ensure stable engraftment.

Inhibition of human tumor cell growth in vivo by an orally bioavailable inhibitor of human farnesyltransferase, BIM-46228

Oncogenic mutations of the ras gene leading to constitutive activation of downstream effectors have been detected in a wide spectrum of human cancers (pancreas, thyroid, colon, non-small-cell lung cancer). Membrane anchorage of Ras, required for functional activity in signal transduction, is facilitated by post-translational modifications resulting in covalent attachment of a farnesyl group to the cysteine in the C-terminal CAAX motif. This attachment is mediated by farnesyltransferase (FTase). Here, we report a novel FTase inhibitor, BIM-46228, which showed (i) specific inhibition of purified human FTase enzyme, (ii) inhibition of proliferation in vitro in a large spectrum of human tumor cell lines, (iii) inhibition of growth of human tumor xenografts in athymic nude mice treated by per os administration and (iv) the benefits of in vitro combination of its activity with chemotherapy or radiotherapy.

The expression of CD70 and CD80 by gene-modified tumor cells induces an antitumor response depending on the MHC status

The expression of costimulatory molecules such as CD70 or CD80 by gene-modified tumor cells has been shown to enhance the antitumor immune response based mainly on T lymphocytes. However, most human tumors show defects of major histocompatibility complex (MHC) expression, preventing them from being recognized by MHC-restricted T cells. To investigate if coexpression of CD70 and CD80 costimulatory molecules induces comparable antitumor responses in low and high MHC-expressing tumor cells, we used two low immunogenic murine tumor models, the B16.F10 melanoma and the TS/A mammary adenocarcinoma cell lines expressing, respectively, low and high levels of MHC class I molecules. Transfection of both CD70 and CD80 genes resulted in an increased capacity of gene-modified tumor cells to costimulate in vitro the proliferation and cytokine production of optimally activated lymphoid cells. Coexpression of CD70 and CD80 by the two tumor cell lines, TS/A and B16.F10, resulted in both cases in partial regression of subcutaneous tumors. Immunochemical analysis and studies in nude mice showed that, even in the B16.F10 model, T cells had a significant role in the antitumor response induced by combining CD70 and CD80. However, rejection of the CD70/CD80-transfected tumor cells appeared more effective in the MHC class I high TS/A model, leading to a protection against parental tumor cells. B16.F10 and TS/A transfectants were then tested with fibroblasts genetically modified to secrete interleukin-12 (IL-12) as a therapeutic vaccine in mice bearing parental tumors. In the two models tested, the injections of irradiated IL-12 and CD70/CD80 gene-modified cells generated an antitumor response to established tumors leading to the slowing down of the tumor growth rate. Although the mechanisms remain to be defined, these findings suggest that the combination of several immuno-modulatory molecules could provide additional strategies for cancer immuno-gene therapy, even for MHC expression-deficient tumors.

[Adult celiac disease: importance of delay to diagnosis]

OBJECTIVE

Adult celiac disease is a genetically determined condition resulting from intolerance to gluten. This familial disease is associated with HLA B8 DR3 and is characterized by cytotoxic T-lymphocyte reaction in the digestive wall leading to a maladsorption syndrome. Adult celiac disease would be an expression of a silent disease already present in childhood.

PATIENTS AND METHODS

We conducted a retrospective study in 19 patients. Diagnosis was established in a department of internal medicine in adulthood. We analyzed histological findings and the clinical history and course.

RESULTS

The age curve at diagnosis peaked at 22 years and 67 years. Female sex predominated. Average delay to diagnosis was 3.1 years. The patients were admitted for reasons other than digestive disorders in 17 out of 19 cases. Careful history taking did however disclose subtle digestive signs. The principal manifestations were hematological disorders such as chronic anemia, abnormal liver function tests, and poor control of associated diseases. Type 1 diabetes mellitus was the main associated disease (4/19). Patients with prolonged nutritional deficiencies experienced serious situations.

CONCLUSION

Adult celiac disease is a clinical variant suggesting the presence of other non-digestive disorders. Specific antibodies should be assayed in patients with even minimal signs of deficiency in order to identify associated diseases. The principal cause of mortality is digestive T-cell lymphoma. A gluten-free diet is essential to control the course of this chronic disease.

Increased stem cell dose, as obtained using currently available technology, may not be sufficient for engraftment of haploidentical stem cell transplants

The best strategies for haploidentical stem cell transplants are not known. We used a standard myeloablative pretransplant conditioning regimen (30 mg/kg VP-16, 120 mg/kg cyclophosphamide, and 12 Gy of TBI in six fractions), an increased peripheral stem cell dose of > 10 x 10(6) CD34+ cells/kg, T cell depletion (with CD34+ cell selection and CD4/CD8 depletion steps) to < 1 x 10(5) CD3+ cells/kg and cyclosporine post transplant. Ten patients (7M/3F, median age 11 (3-33) years) with high-risk leukemia (AML in 4, MDS in 2, CML in 1 and T-ALL in 3) received a hemopoietic stem cell transplant (HSCT) from a haploidentical father or sibling. The median number of CD34+ cells was 12.9 (9.5-45.7) x 10(6) cells/kg; median number of CD3+ cells was 0.41 (0.09-1.89) x 10(5) CD3+ cells/kg. All patients initially achieved 0.5 x 10(9)/l neutrophils at a median 12 (10-21) days. Graft failure in two consecutive patients out of four on the original protocol led to a modification adding ATG pretransplant and OKT3 post transplant. Graft failure was observed in one out of six subsequent patients. Acute GVHD > or = grade II was observed in three patients. Three of 10 patients are alive in CR at > 24 and >3 (2) months after transplant. Seven patients died: four of transplant related complications and three of relapse. Increased stem cell dose (> or = 10 x 10(6) CD34+ cells/kg) as obtained using currently available technology may not be sufficient to ensure stable engraftment in patients with high-risk leukemia using standard myeloablative conditioning regimens.

RhoB prenylation is driven by the three carboxyl-terminal amino acids of the protein: evidenced in vivo by an anti-farnesyl cysteine antibody

Protein isoprenylation is a lipid posttranslational modification required for the function of many proteins that share a carboxyl-terminal CAAX motif. The X residue determines which isoprenoid will be added to the cysteine. When X is a methionine or serine, the farnesyl-transferase transfers a farnesyl, and when X is a leucine or isoleucine, the geranygeranyl-transferase I, a geranylgeranyl group. But despite its CKVL motif, RhoB was reported to be both geranylgeranylated and farnesylated. Thus, the determinants of RhoB prenylation appear more complex than initially thought. To determine the role of RhoB CAAX motif, we designed RhoB mutants with modified CAAX sequence expressed in baculovirus-infected insect cells. We demonstrated that RhoB was prenylated as a function of the three terminal amino acids, i.e., RhoB bearing the CAIM motif of lamin B or CLLL motif of Rap1A was farnesylated or geranylgeranylated, respectively. Next, we produced a specific polyclonal antibody against farnesyl cysteine methyl ester allowing prenylation analysis avoiding the metabolic labeling restrictions. We confirmed that the unique modification of the RhoB CAAX box was sufficient to direct the RhoB distinct prenylation in mammalian cells and, inversely, that a RhoA-CKVL chimera could be alternatively prenylated. Moreover, the immunoprecipitation of endogenous RhoB from cells with the anti-farnesyl cysteine antibody suggested that wild-type RhoB is farnesylated in vivo. Taken together, our results demonstrated that the three last carboxyl amino acids are the main determinants for RhoB prenylation and described an anti-farnesyl cysteine antibody as a useful tool for understanding the cellular control of protein farnesylation.

RhoA prenylation is required for promotion of cell growth and transformation and cytoskeleton organization but not for induction of serum response element transcription

The importance of post-translational geranylgeranylation of the GTPase RhoA for its ability to induce cellular proliferation and malignant transformation is not well understood. In this manuscript we demonstrate that geranylgeranylation is required for the proper cellular localization of V14RhoA and for its ability to induce actin stress fiber and focal adhesion formation. Furthermore, V14RhoA geranylgeranylation was also required for suppressing p21(WAF) transcription, promoting cell cycle progression and cellular proliferation. The ability of V14RhoA to induce focus formation and enhance plating efficiency and oncogenic Ras anchorage-dependent growth was also dependent on its geranylgeranylation. The only biological activity of V14RhoA that was not dependent on its prenylation was its ability to induce serum response element transcriptional activity. Furthermore, we demonstrate that a farnesylated form of V14RhoA was also able to bind RhoGDI-1, was able to induce cytoskeleton organization, proliferation, and transformation, and was just as potent as geranylgeranylated V14RhoA at suppressing p21(WAF) transcriptional activity. These results demonstrate that RhoA geranylgeranylation is required for its biological activity and that the nature of the lipid modification is not critical.

Natural killer-type receptors for HLA class I antigens are clonally expressed in lymphoproliferative disorders of natural killer and T-cell type

In recent years, natural killer (NK) cells, as well as subpopulations of T cells, have been found to express diverse NK receptors (NKRs) for HLA class I molecules. We have characterized NKR phenotypes in lymphoproliferative disorders of NK or T-cell type. Peripheral blood of patients with lymphoproliferative disorders (n = 9) was analysed by multiparametric immunofluorescence flow cytometry with eight different antibodies against NKRs. Abnormal neoplastic cell populations from different types of NK or T-cell lymphoproliferative disorders lacked diversity in their NKR repertoires, i.e. all or none of the abnormal cells expressed individual NKRs and this expression occurred at single levels of intensity. This pattern of expression was specific for lymphoproliferative disorders as these resticted NKR repertoires were not found either in healthy donors (n = 9) or in patients with viral or autoimmune disease (n = 5). We conclude that NKRs are clonally expressed in lymphoproliferative disorders of NK or T-cell origin. NKR repertoires may represent a novel tool in diagnosing clonal disorders of NK and T-cell type.