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Hans-Jürg Leisinger

Publications and source records attributed to Hans-Jürg Leisinger.

16 recordsLinked to original sources
PubMed2006

Peptabody-EGF: a novel apoptosis inducer targeting ErbB1 receptor overexpressing cancer cells.

The epidermal growth factor receptor (EGFR) plays a central role in cell life by controlling processes such as growth or proliferation. This receptor is commonly overexpressed in a number of epithelial malignancies and its upregulation is often associated with an aggressive phenotype of the tumor. Thus, targeting of EGFR represents a very promising challenge in oncology, and antibodies raised against this receptor have been investigated as potential antitumor agents. Various putative mechanisms of action were proposed for such antibodies, including decreased proliferation, induction of apoptosis, stimulation of the immunological response against targeted cancer cells or combinations thereof. We report here the development of an alternative high affinity molecule that is directed against EGFR. Production of this pentameric protein, named peptabody-EGF, includes expression in a bacterial expression system and subsequent refolding and multimerization of peptabody monomers. The protein complex contains 5 human EGF ligand domains, which confer specific binding towards the extracellular portion of EGFR. Receptor binding of the peptabody-EGF had a strong antiproliferative effect on different cancer cell lines overexpressing EGFR. However, cells expressing constitutive levels of the target receptor were barely affected. Peptabody-EGF treated cancer cells exhibited typical characteristics of apoptosis, which was found to be induced within 30 min after the addition of the peptabody-EGF. In vitro experiments demonstrated a significantly higher binding activity for peptabody-EGF than for the therapeutic monoclonal EGFR antibody Mab-425. Furthermore, the antitumor action provoked by the peptabody-EGF was greatly superior than antibody mediated effects when tested on EGFR overexpressing cancer cell lines. These findings suggest a potential application of this high affinity molecule as a novel tool for anti-EGFR therapy.

Amino Acid Sequence↗
PubMed2006

Mutant recombinant serpins as highly specific inhibitors of human kallikrein 14.

The reactive center loop (RCL) of serpins plays an essential role in the inhibition mechanism acting as a substrate for their target proteases. Changes within the RCL sequence modulate the specificity and reactivity of the serpin molecule. Recently, we reported the construction of alpha1-antichymotrypsin (ACT) variants with high specificity towards human kallikrein 2 (hK2) [Cloutier SM, Kündig C, Felber LM, Fattah OM, Chagas JR, Gygi CM, Jichlinski P, Leisinger HJ & Deperthes D (2004) Eur J Biochem271, 607-613] by changing amino acids surrounding the scissile bond of the RCL and obtained specific inhibitors towards hK2. Based on this approach, we developed highly specific recombinant inhibitors of human kallikrein 14 (hK14), a protease correlated with increased aggressiveness of prostate and breast cancers. In addition to the RCL permutation with hK14 phage display-selected substrates E8 (LQRAI) and G9 (TVDYA) [Felber LM, Borgoño CA, Cloutier SM, Kündig C, Kishi T, Chagas JR, Jichlinski P, Gygi CM, Leisinger HJ, Diamandis EP & Deperthes D (2005) Biol Chem386, 291-298], we studied the importance of the scaffold, serpins alpha1-antitrypsin (AAT) or ACT, to confer inhibitory specificity. All four resulting serpin variants ACT(E8), ACT(G9), AAT(E8) and AAT(G9) showed hK14 inhibitory activity and were able to form covalent complex with hK14. ACT inhibitors formed more stable complexes with hK14 than AAT variants. Whereas E8-based inhibitors demonstrated a rather relaxed specificity reacting with various proteases with trypsin-like activity including several human kallikreins, the two serpins variants containing the G9 sequence showed a very high selectivity for hK14. Such specific inhibitors might prove useful to elucidate the biological role of hK14 and/or its implication in cancer.

Base Sequence↗
PubMed2005

[Screening of the prostate cancer. "lnstantaneous" of a daily practice among 300 general practitioners of the canton of Vaud].

This investigation brings information on the practice of 300 general practitioners of the canton of Vaud as for the use of the prostate-specific antigen (PSA) and the digital rectal examination (DRE) in the prostate cancer screening. The high rate of answer shows their interest for this problem which they deal with in adequacy with the international recommendations published by the societies of urology.

Adult↗
PubMed2005

[Prostatitis].

Prostatitis, and particulary chronic pelvic pain syndrome, is a very challenging field in urology. Large randomized placebo treatment trials are necessary for a better evaluation of the different therapeutic options. This article is a review of the evolution in prostatitis diagnostic and actual treatments.

Diagnosis, Differential↗
PubMed2005

[Benign prostatic hyperplasia and sexual dysfunction].

Lower urinary tract symptoms of benign prostatic hyperplasia, erectile dysfunction and ejaculatory disorders are often associated. The severity of sexual dysfunction is positively associated with increasing severity of urinary tract symptoms. Current treatment of BHP produce some effects, positive as well as negative, on the sexual function. It is important to remember this, when you choose a treatment for a patient who report regular sexual activity.

Humans↗
PubMed2005

IB1/JIP-1 controls JNK activation and increased during prostatic LNCaP cells neuroendocrine differentiation.

The scaffold protein Islet-Brain1/c-Jun amino-terminal kinase Interacting Protein-1 (IB1/JIP-1) is a modulator of the c-Jun N-terminal kinase (JNK) activity, which has been implicated in pleiotrophic cellular functions including cell differentiation, division, and death. In this study, we described the presence of IB1/JIP-1 in epithelium of the rat prostate as well as in the human prostatic LNCaP cells. We investigated the functional role of IB1/JIP-1 in LNCaP cells exposed to the proapoptotic agent N-(4-hydroxyphenyl)retinamide (4-HPR) which induced a reduction of IB1/JIP-1 content and a concomittant increase in JNK activity. Conversely, IB1/JIP-1 overexpression using a viral gene transfer prevented the JNK activation and the 4-HPR-induced apoptosis was blunted. In prostatic adenocarcinoma cells, the neuroendocrine (NE) phenotype acquisition is associated with tumor progression and androgen independence. During NE transdifferentiation of LNCaP cells, IB1/JIP-1 levels were increased. This regulated expression of IB1/JIP-1 is secondary to a loss of the neuronal transcriptional repressor neuron restrictive silencing factor (NRSF/REST) function which is known to repress IB1/JIP-1. Together, these results indicated that IB1/JIP-1 participates to the neuronal phenotype of the human LNCaP cells and is a regulator of JNK signaling pathway.

Adaptor Proteins, Signal Transducing↗
PubMed2005

Enzymatic profiling of human kallikrein 14 using phage-display substrate technology.

The human KLK14 gene is one of the newly identified serine protease genes belonging to the human kallikrein family, which contains 15 members. KLK14 , like all other members of the human kallikrein family, is predicted to encode for a secreted serine protease already found in various biological fluids. This new kallikrein is mainly expressed in prostate and endocrine tissues, but its function is still unknown. Recent studies have demonstrated that KLK14 gene expression is up-regulated in prostate and breast cancer tissues, and that higher expression levels correlate with more aggressive tumors. In this work, we used phage-display substrate technology to study the substrate specificity of hK14. A phage-displayed random pentapeptide library with exhaustive diversity was screened with purified recombinant hK14. Highly specific and sensitive substrates were selected from the library. We show that hK14 has dual activity, trypsin- and chymotrypsin-like, with a preference for cleavage after arginine residues. A SwissProt database search with selected sequences identified six potential human protein substrates for hK14. Two of them, laminin alpha-5 and collagen IV, which are major components of the extracellular matrix, have been demonstrated to be hydrolyzed efficiently by hK14.

Bacteriophages↗
PubMed2004

Immediate versus deferred hormonal treatment for patients with prostate cancer who are not suitable for curative local treatment: results of the randomized trial SAKK 08/88.

PURPOSE: To determine if immediate hormonal therapy is advantageous compared with deferred treatment in newly diagnosed asymptomatic prostate cancer patients who, for any reason, were not candidates for curative local treatment. PATIENTS AND METHODS: Between February 1988 and February 1992, 197 patients with a median age of 76 years (range, 56 to 86 years) were randomly assigned to receive either immediate or deferred orchiectomy on symptomatic progression. The two groups did not differ significantly in clinical or laboratory parameters; 67% had T3-4 tumors and 20% had lymph node metastases. Patient accrual was stopped prematurely because of a similar competing trial. Therefore, observation time was prolonged to achieve the desired number of events and statistical power. RESULTS: Deferred orchiectomy was necessary in 58% of the patients. Median time to disease progression was 2.8 years less than for patients with immediate orchiectomy. However, overall pain-free time from random assignment to symptomatic progression after immediate or deferred orchiectomy, and performance status, were identical in both groups. Cancer-specific survival tended to be longer in the immediate group (P = .09) but there was no difference in overall survival between the two groups (P = .96). The median hemoglobin value decreased significantly after immediate orchiectomy (P < .001). CONCLUSION: For elderly, asymptomatic patients not undergoing curative local treatment, we were unable to show any major advantage of immediate compared with deferred hormonal treatment regarding quality of life or overall survival in our limited number of patients. Disabling complications were prevented in the deferred-treatment arm by careful follow-up; 42% of these patients never required any tumor-specific treatment.

Aged↗
PubMed2004

Development of recombinant inhibitors specific to human kallikrein 2 using phage-display selected substrates.

The reactive site loop of serpins undoubtedly defines in part their ability to inhibit a particular enzyme. Exchanges in the reactive loop of serpins might reassign the targets and modify the serpin-protease interaction kinetics. Based on this concept, we have developed a procedure to change the specificity of known serpins. First, reactive loops are very good substrates for the target enzymes. Therefore, we have used the phage-display technology to select from a pentapeptide phage library the best substrates for the human prostate kallikrein hK2 [Cloutier, S.M., Chagas, J.R., Mach, J.P., Gygi, C.M., Leisinger, H.J. & Deperthes, D. (2002) Eur. J. Biochem. 269, 2747-2754]. Selected substrates were then transplanted into the reactive site loop of alpha1-antichymotrypsin to generate new variants of this serpin, able to inhibit the serine protease. Thus, we have developed some highly specific alpha1-antichymotrypsin variants toward human kallikrein 2 which also show high reactivity. These inhibitors might be useful to help elucidate the importance of hK2 in prostate cancer progression.

Bacteriophages↗
PubMed2004

Evaluation of the CFP-substrate-YFP system for protease studies: advantages and limitations.

A protease can be defined as an enzyme capable of hydrolyzing peptide bonds. Thus, characterization of a protease involves identification of target peptide sequences, measurement of activities toward these sequences, and determination of kinetic parameters. Biological protease substrates based on fluorescent protein pairs, which allow for use of fluorescence resonance energy transfer (FRET), have been recently developed for in vivo protease activity detection and represent a very interesting alternative to chemical substrates for in vitro protease characterization. Here, we analyze a FRET system consisting of cyan and yellow fluorescent proteins (CFP and YFP, respectively), which are fused by a peptide linker serving as protease substrate. Conditions for CFP-YFP fusion protein production in Escherichia coli and purification of proteins were optimized. FRET between CFP and YFP was found to be optimum at a pH between 5.5 and 10.0, at low concentrations of salt and a temperature superior to 25 degrees C. For efficient FRET to occur, the peptide linker between CFP and YFP can measure up to 25 amino acids. The CFP-substrate-YFP system demonstrated a high degree of resistance to nonspecific proteolysis, making it suitable for enzyme kinetic analysis. As with chemical substrates, substrate specificity of CFP-substrate-YFP proteins was tested towards different proteases and kcat/Km values were calculated.

Enzyme Activation↗
PubMed2003

Hexyl aminolevulinate fluorescence cystoscopy: new diagnostic tool for photodiagnosis of superficial bladder cancer--a multicenter study.

PURPOSE: We examined the sensitivity and specificity of Hexvix (PhotoCure ASA, Oslo, Norway) hexyl aminolevulinate (HAL) fluorescence cystoscopy in patients with superficial bladder cancer. MATERIALS AND METHODS: A total of 52 patients (38 men and 14 women) with a mean age of 72 years were investigated. HAL hydrochloride (100 mg dissolved in 50 ml phosphate buffer solution) (8 mM) was instilled into the bladder 1 hour prior to the endoscopic procedure. Cystoscopy was performed with the Storz D-light (Karl Storz, Tuttlingen, Germany) system, allowing inspection of the bladder wall under white and blue light (380 to 450 nm). RESULTS: A total of 422 biopsies obtained in fluorescing (165) and nonfluorescing (257) areas, including 5 random biopsies per patient, were analyzed to provide the best reference for the calculation of sensitivity and specificity. There were a total of 143 histologically verified tumors in 45 patients, including carcinoma in situ (CIS), Ta or T1 lesions. A total of 43 patients were diagnosed by fluorescence cystoscopy compared with 33 diagnosed by white light for 96% and 73% per-patient sensitivity, respectively. HAL cystoscopy was found particularly useful for finding CIS tumors. Of 13 patients with CIS tumors all except 1 were diagnosed or confirmed by HAL cystoscopy. HAL cystoscopy was well tolerated with no definite drug related adverse events reported, including effects on standard blood parameters. CONCLUSIONS: HAL fluorescence cystoscopy is a new, sensitive, promising diagnostic procedure that showed improved detection of bladder tumors, in particular CIS. The procedure is well tolerated and can easily be implemented in current clinical practice.

Aged↗
PubMed2002

The scaffold protein IB1/JIP-1 controls the activation of JNK in rat stressed urothelium.

The c-Jun N-terminal kinase (JNK) is critical for cell survival, differentiation, apoptosis and tumorigenesis. This signalling pathway requires the presence of the scaffold protein Islet-Brain1/c-Jun N-terminal kinase interacting protein-1 (IB1/JIP-1). Immunolabeling and in situ hybridisation of bladder sections showed that IB1/JIP-1 is expressed in urothelial cells. The functional role of IB1/JIP-1 in the urothelium was therefore studied in vivo in a model of complete rat bladder outlet obstruction. This parietal stress, which is due to urine retention, reduced the content of IB1/JIP-1 in urothelial cells and consequently induced a drastic increase in JNK activity and AP-1 binding activity. Using a viral gene transfer approach, the stress-induced activation of JNK was prevented by overexpressing IB1/JIP-1. Conversely, the JNK activity was increased in urothelial cells where the IB1/JIP-1 content was experimentally reduced using an antisense RNA strategy. Furthermore, JNK activation was found to be increased in non-stressed urothelial cells of heterozygous mice carrying a selective disruption of the IB1/JIP-1 gene. These data established that mechanical stress in urothelial cells in vivo induces a robust JNK activation as a consequence of regulated expression of the scaffold protein IB1/JIP-1. This result highlights a critical role for that scaffold protein in the homeostasis of the urothelium and unravels a new potential target to regulate the JNK pathway in this tissue.

Adaptor Proteins, Signal Transducing↗
PubMed2002

The role of retroperitoneal surgery in testis cancer.

Testis cancer is today a curable malignancy. But controversy remains about the appropriate management of patients presenting different stages. There is an increasing interest in surveillance rather than in primary retroperitoneal lymph node dissection (RPLND) for stage I non-seminomatous germ cell tumors (NSGCT). Adjuvant chemotherapy has become an efficient treatment option for high risk non-seminomatous germ cell testis cancer, however, biological and histologic risk factors of the primary tumor are not yet precisely defined. To determine the appropriate management of patients with testicular cancer, postoperative morbidity after RPLND and risk of chemotherapy-induced morbidity must be balanced. Whoever reviews the literature must take into consideration that the excellent postoperative results after RPLND depend on high volume and large experience with testis cancer. As treatment morbidity and its intensity have a major impact on testis cancer patient quality of life, the choice of management must be based on the patient's social situation, his personal needs, and the doctor's experience and resources.

Antineoplastic Agents↗
PubMedDate not supplied

Profiling of proteolytic activities secreted by cancer cells using phage display substrate technology.

Although the cellular steps required for metastasis are similar for all cancer cells, proteases involved in this process and their expression levels vary greatly between different cancer types. Thus, the identification of these proteolytic activities represents a crucial issue in the understanding of cancer development. Until now, phage display substrate technology has been successfully employed for the characterization of purified proteases but was never used with a mix of proteases. In the present work, we report an easy protocol to identify multiple proteolytic activities secreted by cancer cells. We selected substrates from a phage display library of high diversity using secreted media of three established prostate cancer cell lines (DU-145, LNCaP and PC-3) with variable degrees of invasive capability. Some of these selected peptide substrates were hydrolyzed by the secreted proteins of all three prostatic cancer cell lines, demonstrating similarities in their proteolytic activities. On the other hand, a few substrates were cancer cell specific, indicating differences in the phenotypes of protease expression in prostate cancer. This work reports for the first time the selection of substrates from a mix of proteases using phage display technology and opens a new avenue for the direct identification of proteolytic activities for tumor extracts.

Endopeptidases↗