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Abstract Background Topoisomerase I (TOP1) is a nuclear enzyme that catalyzes the relaxation of supercoiled DNA during DNA replication and transcription. TOP1 is the molecular target of camptothecin and related drugs such as irinotecan and SN38 (irinotecan's active metabolite). Irinotecan is widely used as an anti-cancer agent in the treatment of metastatic colon cancer. However, its efficacy is often limited by the development of resistance. Methods We previously established several SN38 resistant HCT116-derived clones to study the mechanisms underlying resistance to SN38. Here, we investigated whether resistance to SN38 in these cell lines could be linked to the presence of TOP1 mutations and changes in its expression and activity. Functional analyses were performed on these cell lines challenged with SN38 and we specifically monitored the double strands breaks with γH2AX staining and replication activity with molecular combing. Results In SN38 resistant HCT116 clones we identified three new TOP1 mutations, which are located in the core subdomain III (p.R621H and p.L617I) and in the linker domain (p.E710G) and are packed together at the interface between these two domains. The presence of these TOP1 mutations in SN38 resistant HCT116 cells did not modify TOP1 expression or intrinsic activity. Conversely, following challenge with SN38, we observed a decrease of TOP1-DNA cleavage complexes and a reduction in double-stranded break formation). In addition, we showed that SN38 resistant HCT116 cells present a strong decrease in the SN38-dependent asymmetry of replication forks that is characteristic of SN38 sensitive HCT116 cells. Conclusions These results indicate that the TOP1 mutations are involved in the development of SN38 resistance. We hypothesize that p.L617, p.R621 and p.E710 TOP1 residues are important for the functionality of the linker and that mutation of one of these residues is sufficient to alter or modulate its flexibility. Consequently, linker fluctuations could have an impact on SN38 binding by reducing the enzyme affinity for the drug.

Background: Regorafenib has shown substantial clinical activity in patients with advanced biliary tract cancers (BTCs). Preclinical data suggested that this drug modulates antitumour immunity and is synergistic with immune checkpoint inhibition., Patients and Methods: This is a single-arm, multicentric phase II trial. Regorafenib was given 3 weeks/4, 160 mg quaque die (once a day) (QD); avelumab 10 mg/kg IV was given every two weeks, beginning at C1D15 until progression or unacceptable toxicity. The primary end-point was the confirmed objective response rate under treatment, as per Response Evaluation Criteria in Solid Tumours 1.1. The secondary end-points included the following: 1-year non-progression rate; progression-free survival (PFS) and overall survival; safety and biomarkers studies performed on sequential tumour samples obtained at baseline and at cycle 2 day 1., Results: Thirty-four patients were enrolled in four centres. Twenty-nine patients were assessable for efficacy after central radiological review. The best response was partial response for four patients (13.8%), stable disease for 11 patients (37.9%) and progressive disease for 14 patients (48.3%). The median PFS and overall survival were 2.5 months (95% confidence interval [CI] [1.9-5.5]) and 11.9 months (95%CI [6.2-NA]) respectively. The most common grade 3 or 4 clinical adverse events related to treatment were hypertension (17.6%), fatigue (14.7%) and maculopapular rash (11.8%). High baseline levels of programmed cell death ligand 1 and of indoleamine 2, 3-dioxygénase expression were associated with improved outcomes., Conclusions: Regorafenib combined with avelumab has antitumour activity in a subset of heavily pretreated biliary tract cancer population. Further investigations are needed in patients selected based on tumour microenvironment features., Clinical Trial Registration: NCT03475953., Competing Interests: Conflict of interest statement AB, CR and JPG: employees from Immusmol/Explicyte. AI: research grants MSD, BMS, ROCHE and personal fees: Epizyme, Bayer, Lilly, Roche, Springworks; non-financial support: Merck. All remaining authors have declared no conflicts of interest., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Background: Soft-tissue sarcomas (STS) represent a heterogeneous group of rare tumors including more than 70 different histological subtypes. High throughput molecular analysis (next generation sequencing exome [NGS]) is a unique opportunity to identify driver mutations that can change the usual one-size-fits-all treatment paradigm to a patient-driven therapeutic strategy. The primary objective of the MULTISARC trial is to assess whether NGS can be conducted for a large proportion of metastatic STS participants within a reasonable time, and, secondarily to determine whether a NGS-guided therapeutic strategy improves participant's outcome., Methods: This is a randomized, multicentre, phase II/III trial inspired by the design of umbrella and biomarker-driven trials. The setting plans up to 17 investigational centres across France and the recruitment of 960 participants. Participants aged at least 18 years, with unresectable locally advanced and/or metastatic STS confirmed by the French sarcoma pathological reference network, are randomized according to 1:1 allocation ratio between the experimental arm "NGS" and the standard "No NGS". NGS will be considered feasible if (i) NGS results are available and interpretable, and (ii) a report of exome sequencing including a clinical recommendation from a multidisciplinary tumor board is provided to investigators within 7 weeks from reception of the samples on the biopathological platform. A feasibility rate of more than 70% is expected (null hypothesis: 70% versus alternative hypothesis: 80%). In terms of care, participants randomized in "No NGS" arm and who fail treatment will be able to switch to the NGS arm at the request of the investigator., Discussion: The MULTISARC trial is a prospective study designed to provide high-level evidence to support the implementation of NGS in routine clinical practice for advanced STS participants, on a large scale., Trial Registration: clinicaltrial.gov NCT03784014 ., (© 2021. The Author(s).)

Purpose: Regorafenib is synergistic with immune checkpoint inhibition in colorectal cancer preclinical models., Patients and Methods: This was a single-arm, multicentric phase II trial. Regorafenib was given 3 weeks on/1 week off, 160 mg every day; avelumab 10 mg/kg i.v. was given every 2 weeks, beginning at cycle 1, day 15 until progression or unacceptable toxicity. The primary endpoint was the confirmed objective response rate under treatment, as per RECIST 1.1. The secondary endpoints included a 1-year nonprogression rate, progression-free survival (PFS), and overall survival (OS), safety and biomarkers studies performed on sequential tumor samples obtained at baseline and at cycle 2 day 1., Results: Forty-eight patients were enrolled in four centers. Forty-three were assessable for efficacy after central radiological review. Best response was stable disease for 23 patients (53.5%) and progressive disease for 17 patients (39.5%). The median PFS and OS were 3.6 months [95% confidence interval (CI), 1.8-5.4] and 10.8 months (95% CI, 5.9-NA), respectively. The most common grade 3 or 4 adverse events were palmar-plantar erythrodysesthesia syndrome ( n = 14, 30%), hypertension ( n = 11, 23%), and diarrhea ( n = 6, 13%). High baseline infiltration by tumor-associated macrophages was significantly associated with adverse PFS (1.8 vs. 3.7 months; P = 0.002) and OS (3.7 months vs. not reached; P = 0.002). Increased tumor infiltration by CD8 + T cells at cycle 2, day 1 as compared with baseline was significantly associated with better outcome., Conclusions: The combination of regorafenib + avelumab mobilizes antitumor immunity in a subset of patients with microsatellite stable colorectal cancer. Computational pathology through quantification of immune cell infiltration may improve patient selection for further studies investigating this approach., (©2021 American Association for Cancer Research.)

Background: Cytochrome P450 1B1 (CYP1B1) is mostly expressed in tumours and displays unusual properties. Its two polymorphic forms were differently associated with anticancer drug sensitivity. We decipher here the role of this polymorphism in anticancer drug efficacy in vitro, in vivo and in the clinical setting., Methods: From head-and-neck squamous cell carcinoma cell lines not expressing CYP1B1, we generated isogenic derivatives expressing the two forms. Proliferation, invasiveness, stem cell characteristics, sensitivity to anticancer agents and transcriptome were analysed. Tumour growth and chemosensitivity were studied in vivo. A prospective clinical trial on 121 patients with advanced head-and-neck cancers was conducted, and a validation-retrospective study was conducted., Results: Cell lines expressing the variant form displayed high rates of in vitro proliferation and invasiveness, stemness features and resistance to DNA-damaging agents. In vivo, tumours expressing the variant CYP1B1 had higher growth rates and were markedly drug-resistant. In the clinical study, overall survival was significantly associated with the genotypes, wild-type patients presenting a longer median survival (13.5 months) than the variant patients (6.3 months) (p = 0.0166)., Conclusions: This frequent CYP1B1 polymorphism is crucial for cancer cell proliferation, migration, resistance to chemotherapy and stemness properties, and strongly influences head-and-neck cancer patients' survival.

Background: Whole exome sequencing and RNA sequencing (WES/RNASeq) should now be implemented in the clinical practice in order to increase access to optimal care for cancer patients. Providing results to Tumour Boards in a relevant time frame-that is, compatible with the clinical pathway-is crucial. Assessing the feasibility of this implementation in the French care system is the primary objective of the Multipli study, as one of the four pilot projects of the national France Genomic Medicine 2025 (FGM 2025) plan. The Multipli study encompasses two innovative trials which will be driven in around 2400 patients suffering from a soft-tissue sarcoma (Multisarc) or a metastatic colorectal carcinoma (Acompli)., Methods: Prior to launching the FGM 2025 cancer pilot study itself, the performance of the Multipli genomic workflow has been evaluated through each step, from the samples collection to the Molecular Tumour Board (MTB) report. Two Multipli-assigned INCa-labelled molecular genetics centres, the CEA-CNRGH sequencing platform and the Institut Bergonié's Bioinformatics Platform were involved in a multicentric study. The duration of each step of the genomic workflow was monitored and bottlenecks were identified., Results: Thirty barriers which could affect the quality of the samples, sequencing results and the duration of each step of the genomic pathway were identified and mastered. The global turnaround time from the sample reception to the MTB report was of 44 calendar days., Conclusion: Our results demonstrate the feasibility of tumour genomic analysis by WES/RNASeq within a time frame compatible with the current cancer patient care. Lessons learnt from the Multipli WES/RNASeq Platforms Workflow Study will constitute guidelines for the forthcoming Multipli study and more broadly for the future clinical routine practice in the first two France Genomic Medicine 2025 platforms., Competing Interests: Competing interests: None declared., (© Author (s) (or their employer(s)) 2020. Re-use permitted under CC BY. Published by BMJ on behalf of the European Society for Medical Oncology.)

We recently synthesized from aconitine a series of drugs with in vitro and in vivo antitumor properties, among which bis[O-(14-benzoylaconine-8-yl)]suberate (BBAS) was the most active (Eur J Med Chem 2012; 54: 343). In the present work, we used the NCI panel of 60 human tumor cell lines to identify the most sensitive cell lines and drugs with comparable cytotoxicity profiles. GI50 values of BBAS ranged between 0.12 and 6.5 μM. Activity was higher than average for leukemia and melanoma cell lines, especially SK-MEL-5 and SK-MEL-28, for the COLO-205 and HT-29 (colorectal) and MDA-MB-468 (breast) cancer cell lines. We evaluated the correlation between the GI50 of BBAS and those of 125 antiproliferative compounds with various mechanisms of action, using Bonferroni correction for multiple testing, and we observed a highly significant correlation with the GI50s of nitrosoureas. Interestingly, BBAS cytotoxicity was inversely correlated with the expression levels of MGMT (p = 0.009), an enzyme involved in the repair of nitrosourea-induced DNA damage. However, no correlation was found with the expression of 102 other genes involved in DNA repair. Antitumor activity was tested on immunodeficient mice with subcutaneously xenografted COLO-205, HT-29, MDA-MB-468, SK-MEL-5 and SK-MEL-28 cell lines. At 10 mg/kg, there was a significant reduction in tumor size with T/C values of 41 % and 43 % for COLO-205 and SK-MEL-28 cell lines, respectively. The drug was less active on HT-29 and SK-MEL-5 and inactive on MDA-MB-468 xenografts. Cell cycle studies showed an accumulation of BBAS-treated cells in G2/M phase after treatment at 20 μM. Together, our results allowed the identification of a potentially new class of anticancer agent displaying a mechanism of action related to that of nitrosoureas.

A novel bimodal fluorescent/radiolabelled probe based on a pyridyltriazole scaffold (known as pyta) is reported here. The final dual imaging agent combines carboxylate functionalization, for biomolecule conjugation, with two distinct metal chelating sites: a pyta-based tricarbonylrhenium moiety as a fluorescent probe and a (99m)Tc(CO3)(+) core through the tridentate chelating iminodiacetic acid (IDA) clamp as a SPECT reporter. The heterodinuclear (99m)Tc/Re complex , as well as its non-radioactive dirhenium analog , was prepared in six steps. The (99m)Tc/Re agent is water-soluble and stable against histidine challenge. Its structural characterization was achieved by HPLC comparison with the non-radioactive complex . Upon excitation in the MLCT band at 321 nm, the compound exhibits a bright green luminescence centered at 496 nm, with a quantum yield of 0.86% in Tris buffer, pH 7.4. Additionally, the influence of this compound on cell viability was tested on malignant cell lines (A549, HT29 and MCF-7 human lung, colon and breast carcinomas, respectively). Cell viability after 72 h incubation at 37 °C with 300 μmol of complex was >60% for all cell lines. Finally, cellular uptake studies of compound were performed by fluorescent microscopy, showing that the complex was clearly detected at the cellular level in A549 cells and to a lesser extent in HT29 cells. Taking into consideration the luminescent properties, the good radiochemical purity and the promising biological data (in vitro stability, non-toxicity, and cell tracking in two cell lines), the functionalized (99m)Tc/Re dinuclear compound can be considered a potential pre- and intraoperative diagnostic probe.

Polyphenolic ellagitannins are natural compounds that are often associated with the therapeutic activity of plant extracts used in traditional medicine. They display cancer-preventing activity in animal models by a mechanism that remains unclear. Potential targets have been proposed, including DNA topoisomerases II (Top2). Top2α and Top2β, the two isoforms of the human Top2, play a crucial role in the regulation of replication, transcription, and chromosome segregation. They are the target of anticancer agents used in the clinic such as anthracyclines (e.g., doxorubicin) or the epipodophyllotoxin etoposide. It was recently shown that the antitumor activity of etoposide was due primarily to the inhibition of Top2α, whereas inhibition of Top2β was responsible for the development of secondary malignancies, pointing to the need for more selective Top2α inhibitors. Here, we show that the polyphenolic ellagitannin vescalagin preferentially inhibits the decatenation activity of Top2α in vitro, by a redox-independent mechanism. In CEM cells, we also show that transient small interfering RNA-mediated down-regulation of Top2α but not of Top2β conferred a resistance to vescalagin, indicating that the α isoform is a preferential target. We further confirmed that Top2α inhibition was due to a catalytic inhibition of the enzyme because it did not induce DNA double-strand breaks in CEM-treated cells but prevented the formation of Top2α- rather than Top2β-DNA covalent complexes induced by etoposide. To our knowledge, vescalagin is the first example of a catalytic inhibitor for which cytotoxicity is due, at least in part, to the preferential inhibition of Top2α.

Background: Topoisomerase I (TOP1) is a nuclear enzyme that catalyzes the relaxation of supercoiled DNA during DNA replication and transcription. TOP1 is the molecular target of camptothecin and related drugs such as irinotecan and SN38 (irinotecan's active metabolite). Irinotecan is widely used as an anti-cancer agent in the treatment of metastatic colon cancer. However, its efficacy is often limited by the development of resistance., Methods: We previously established several SN38 resistant HCT116-derived clones to study the mechanisms underlying resistance to SN38. Here, we investigated whether resistance to SN38 in these cell lines could be linked to the presence of TOP1 mutations and changes in its expression and activity. Functional analyses were performed on these cell lines challenged with SN38 and we specifically monitored the double strands breaks with γH2AX staining and replication activity with molecular combing., Results: In SN38 resistant HCT116 clones we identified three new TOP1 mutations, which are located in the core subdomain III (p.R621H and p.L617I) and in the linker domain (p.E710G) and are packed together at the interface between these two domains. The presence of these TOP1 mutations in SN38 resistant HCT116 cells did not modify TOP1 expression or intrinsic activity. Conversely, following challenge with SN38, we observed a decrease of TOP1-DNA cleavage complexes and a reduction in double-stranded break formation). In addition, we showed that SN38 resistant HCT116 cells present a strong decrease in the SN38-dependent asymmetry of replication forks that is characteristic of SN38 sensitive HCT116 cells., Conclusions: These results indicate that the TOP1 mutations are involved in the development of SN38 resistance. We hypothesize that p.L617, p.R621 and p.E710 TOP1 residues are important for the functionality of the linker and that mutation of one of these residues is sufficient to alter or modulate its flexibility. Consequently, linker fluctuations could have an impact on SN38 binding by reducing the enzyme affinity for the drug.

Sertoli cells provide a controlled microenvironment for regulation and maintenance of spermatogenesis for which an acidic milieu is crucial for male fertility. Sertoli cells also contribute to protection of spermatogenetic cells. Here, we showed that TRPV1 is expressed in rat Sertoli cells and regulates an acid sensing Cl(-) channel (ASCC). The expression of TRPV1 in rat Sertoli cells was demonstrated by RT-PCR, immunostaining and calcium measurement experiments. ASCC activity was inhibited by capsaicin (IC(50)=214.3+/-1.6 nM), olvanil (IC(50)=400+/-1.7 pM) and resiniferatoxin (IC(50)=9.3+/-1.5 nM) but potentiated by capsazepine (EC(50)=5.3+/-1.3 microM) and ruthenium red (EC(50)=2.3+/-1.5 microM). In the human airway epithelial cell line Calu-3 in which ASCC can be detected but not TRPV1, capsaicin and capsazepine were without any effect. Finally the application of the non-steroidal anti-inflammatory drug ibuprofen prevented the control of ASCC by TRPV1. Our study provides the first evidence for a regulation by TRPV1 of an acid sensing chloride channel in rat Sertoli cells. TRPV1 and ASCC may thus be considered as new potential physiological regulators of spermatogenesis and targets for pharmacological treatments of reproductive disorders as cryptorchidism, Sertoli cell tumors or torsion of the spermatic cord.

Sertoli cells from mammalian testis are key cells involved in the development and maintenance of stem cell spermatogonia as well as in the secretion of a Cl(-) and K(+)-rich fluid into the lumen of seminiferous tubules. The pharmacology and contribution of Cl(-) channels to the physiology of Sertoli cells were investigated using whole-cell patch clamp and iodide efflux experiments applied to cultured rat Sertoli cells. We characterized an outwardly rectifying Cl(-) current stimulated by various acid species including the physiologically relevant lactic acid. Using the iodide efflux technique, the pharmacological properties of this Cl(-) current, noted ICl(acid), revealed Ca(2+)-independent inhibition by DIDS (IC(50) = 27 microM), glibenclamide (IC(50) = 31 microM) and DPC (IC(50) = 86 microM). ICl(acid) was neither affected by calix[4]arene nor by 9-AC. The order of potency for inhibition of ICl(acid) is DIDS approximately glibenclamide > DPC >> calix[4]arene, 9-AC. For comparison, the inhibitory profile of the swelling- and ATP-activated Cl(-) currents in Sertoli cells is DPC = DIDS >> glibenclamide = 9-AC for ICl(swell) and DPC = 9-AC = DIDS >> glibenclamide for ICl(ATP). This description provides new insights into the physiology and pharmacology of the endogenous Cl(-) channels expressed and potentially involved in fluid secretion in Sertoli cells.

The vacuolar H(+)-ATPase (V-ATPase) is a ubiquitous multisubunit pump that is responsible for acidification of intracellular organelles. In the kidney, a particular form of V-ATPase, made of specific subunits isoforms, has been located at the plasma membrane of intercalated cells (IC). Mutations in genes encoding IC-specific subunits cause infant distal renal tubular acidosis (dRTA), suggesting that the segmental distribution of these subunits is acquired at birth or during early infancy. However, the comparative ontogeny of the IC-specific versus the ubiquitous subunits of V-ATPase and the mechanisms involved in their segmental expression remain unknown. Real-time reverse transcription-PCR, in situ hybridization, immunoblotting, immunostaining, and subcellular fractionation analyses characterized the expression and distribution of V-ATPase subunits, transcription factors, and differentiation markers during mouse nephrogenesis. Ubiquitous A, E1, B2, G1, and C1 subunits showed an early (embryonic day 13.5 [E13.5]) and stable expression throughout nephrogenesis, followed by a slight increase around birth. The developmental pattern of a1 was bimodal, with early induction, gradual decrease during organogenesis, and neonatal increase. These patterns contrasted with the later (from E15.5) and progressive expression of IC-specific a4, B1, G3, and C2 subunits, after the induction of the forkhead transcription factor Foxi1. From E15.5, Foxi1 mRNA was detected in IC, where it co-distributed with B1 in late nephrogenesis. Immunostaining showed that the distribution of ubiquitous E1 and B2 was acquired from E15.5, whereas a4 was located in IC during late nephrogenesis. Subcellular fractionation showed that in both fetal and mature (cortex and medulla) kidneys, E1 and a4 were located in endosomes. These data demonstrate a differential expression and a coordinate regulation of IC-specific versus ubiquitous V-ATPase subunits during nephrogenesis. They provide new insights into the complex regulation of V-ATPase subunits, the maturation of IC along the nephron, and the pathophysiology of hereditary dRTA.

Objectives: To evaluate the current diagnostic and therapeutic management of acute prostatitis., Material and Methods: The authors report a series of 100 consecutive patients with a diagnosis of acute prostatitis managed between January 1999 and December 2003. They analysed the clinical and laboratory data and imaging findings leading to the diagnosis of acute prostatitis and then the modalities of treatment and follow-up of these patients., Results: The median age was 56.5 years (range: 19-86 years). In 77% of cases, the initial septic syndrome was considered to be severe. Prostatic tenderness was detected on digital rectal examination in 68% of cases. In 76% of cases, the micro-organism responsible was Escherichia coli. 8% of patients had positive blood cultures. All patients presented laboratory signs of inflammatory syndrome, with elevated C Reactive Protein (CRP) in most cases. Renal and bladder ultrasound was performed in 49% of cases and CT was performed in 16% of cases. 92% of patients were treated with fluoroquinolones, as monotherapy in 34% of cases. The duration of prescription ranged from 2 weeks to 6 weeks. No aetiology was detected in 48% of cases, 8% were considered to be iatrogenic and 44% were associated with incomplete bladder emptying., Conclusion: Acute prostatitis, rapidly treated by aggressive and adapted antibiotics has a rapidly favourable outcome. Elevation of CRP and the presence of leukocyturia on urine dipsticks are almost constant and, when they are normal, the diagnosis of acute prostatitis should be questioned. Imaging is not required in the absence of diagnostic doubt and any suspicion of progression to abscess. The duration of antibiotic therapy varies from prescriber to prescriber reflecting the various guidelines. Guidelines on this subject are contradictory and further effort is required to achieve homogenization and application of these guidelines.

Dent's disease is a hereditary renal tubular disorder characterized by low-molecular weight (LMW) proteinuria, hypercalciuria and nephrolithiasis. The disease is due to mutations of ClC-5, a member of the family of voltage-gated CLC chloride channels. ClC-5 is expressed in part in cells lining the proximal tubule (PT) of the kidney, where it colocalizes with albumin-containing endocytic vesicles belonging to the receptor-mediated endocytic pathway that ensures efficient reabsorption of ultrafiltrated LMW proteins. Since progression along the endocytic apparatus requires endosomal acidification, it has been suggested that dysfunction of ClC-5 in endosomes may lead to inefficient reabsorption of LMW proteins and dysfunction of PT cells. Analysis of a ClC-5 knockout (KO) mouse model, displaying all the characteristic renal tubular defects of Dent's disease, showed evidence of a severe LMW proteinuria. Cytochemical studies with the endocytic tracer, peroxidase, showed poor transfer into early endocytic vesicles, suggesting that impairment of receptor-mediated endocytosis in PT cells is the basis for the defective uptake of LMW proteins in patients with Dent's disease. Endocytosis and processing of LMW proteins involve the multiligand tandem receptors, megalin and cubilin, that are abundantly expressed at the brush border of PT cells. Characterization of the endocytic defect in ClC-5 KO mice revealed that ligands of both megalin and cubilin were affected. The total kidney content of megalin and especially cubilin at the protein level was decreased but, more importantly, using analytical subcellular fractionation and quantitative immunogold labelling we demonstrated a selective disappearance of megalin and cubilin at the brush border of PT cells. These observations allowed us to conclude that defective protein endocytosis linked to ClC-5 inactivation is due at least in part to a major and selective loss of megalin and cubilin at the brush border, reflecting a trafficking defect in renal PT cells. These results improve our understanding of Dent's disease, taken as a paradigm for renal Fanconi syndrome and nephrolithiasis, and demonstrate multiple roles for ClC-5 in the kidney. These studies also provided insights into important functions such as apical endocytosis, handling of proteins by renal tubular cells, calcium metabolism, and urinary acidification., (Copyright (c) 2005 S. Karger AG, Basel.)

Flux studies using either radioisotopes or ion-selective electrodes are a convenient method to assay the function of the cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel. Here, we described three different protocols to study the properties, regulation and pharmacology of the CFTR Cl- channel in populations of cells and artificial vesicles. These techniques are widely used to evaluate the function of wild-type and mutant CFTR prior to detailed analyses using the patch-clamp technique. Moreover, they have proved especially valuable in the search for new drugs to treat cystic fibrosis.

Sertoli cells from mammalian testis are key cells involved in development and maintenance of stem cell spermatogonia as well as secretion of a chloride- and potassium-rich fluid into the lumen of seminiferous tubules. Using whole-cell patch clamp experiments, a novel chloride current was identified. It is activated only in the presence of an extracellular acidic pH, with an estimated half-maximal activation at pH 5.5. The current is strongly outwardly rectifying, activated with a fast time-dependent onset of activation but a slow time-dependent kinetic at depolarization pulses. The pH-activated chloride current was not detected at physiological or basic pH and is not sensitive to intracellular or extracellular Ca2+ variation. Diphenylamine-2-carboxylic acid and 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid blocked the induced currents, and its anionic selectivity sequence was Cl- > Br- > I-> gluconate. We have performed a reverse transcription-PCR analysis to search for voltage-dependent chloride rClC channels in cultured rat Sertoli cells. Among the nine members of the family only rClC-2, rClC-3, rClC-6, and rClC-7 have been identified. The inwardly rectifying rClC-2 chloride current was activated by hyperpolarization but not by pH variation. A different depolarization-activated outwardly rectifying chloride current was activated only by hypotonic challenge and may correspond either to rClC-3 or rClC-6. Immunolocalization experiments demonstrate that rClC-7 resides in the intracellular compartment of Sertoli cells. This study provides the first functional identification of a native acid-activated chloride current. Based on our molecular analysis of rClC proteins, this new chloride current does not correspond to rClC-2, rClC-3, rClC-6, or rClC-7 channels. The potential physiological role of this native current in an epithelial cell from the reproductive system is discussed.

Introduction: Endocrine therapy is the standard first-line treatment for metastatic prostate cancer. The use of this treatment modality for a number of years in a large population has demonstrated some of its iatrogenic complications, especially bone complications. Hypogonadism induced by chemical castration can be responsible for osteoporosis that may be complicated by fractures., Objective: Evaluation of the prevalence of fractures in nonmetastatic sites., Patients and Method: Retrospective study of 49 patients treated for more than 5 years by endocrine therapy with determination of the fracture rate, mechanisms and fracture sites., Results: Eight patients developed fractures after antiandrogen treatment. Three patients with a traumatic or metastatic fracture were excluded. Five patients (10.2%) were considered to present osteoporotic fractures on the basis of their site (vertebra and neck of femur) or their mechanism (minor trauma). The mean duration of treatment in these patients was 8.1 years. The prevalence of osteoporotic fractures in the general population is estimated to be 2.2 per 1,000 men between the ages of 65 and 80 years and 6.4 per 1,000 men after the age of 80 years., Conclusion: The prevalence of osteoporosis induced by endocrine therapy is increasing due to longer patient survival and early introduction of treatment. No prophylactic treatment is currently proposed when starting endocrine therapy.