Clinical prospects of long noncoding RNAs as novel biomarkers and therapeutic targets in prostate cancer.

BACKGROUND: The lack of sensitive and specific biomarkers for prostate cancer (PCa) has led to over-diagnosis and overtreatment with uncertain benefit. Therefore, biomarkers for early diagnosis that can distinguish aggressive from indolent tumors and that can detect metastatic or recurrent disease are needed. Long noncoding RNAs (lncRNAs) are non-protein-coding RNA species. lncRNAs are dysregulated in many diseases including PCa and are emerging as major players in cancer development. lncRNAs have several features that make then suitable as both biomarkers and therapeutics, and lncRNAs regulate critical cancer hallmarks in prostate epithelial cells including proliferation and survival. METHODS: The PubMed database was searched using the terms 'long noncoding RNA', 'biomarker' and 'prostate cancer'. Known lncRNAs implicated as biomarkers and potential therapeutic targets in PCa are reviewed. RESULTS: We comprehensively review several lncRNAs with potential as biomarkers for PCa. lncRNAs including PCA3, PCATs, SChLAP1, SPRY4-IT1 and TRPM2-AS are upregulated in PCa and are cancer specific; they are, therefore, attractive lead candidate biomarkers for clinical application. Several lncRNA therapeutics are currently being investigated by several companies for the treatment of various cancers including PCa. Small interfering RNAs, antisense oligonucleotides, ribozymes, deoxyribozymes and aptemers are few promising technologies for future lncRNA bases therapeutics. CONCLUSION: lncRNA expression is altered in cancer. Aberrant regulation promotes tumor formation, progression and metastasis. lncRNAs can use as tumor markers for PCa and may be attractive novel therapeutic targets for the diagnosis and treatment of PCa.

Grey Zones in the Field of Urinary Tract Infections.

Urinary tract infections are a very common clinical problem with various knowledge gaps requiring urgent attention in areas including pathophysiology, diagnosis, antibiotic resistance, and prophylaxis. These grey zones preclude optimal management of urologic patients.

Feasibility study of a randomised controlled trial to compare (deferred) androgen deprivation therapy and cryotherapy in men with localised radiation-recurrent prostate cancer.

BACKGROUND: Salvage therapeutic options for biochemical failure after primary radiation-based therapy include radical prostatectomy, cryoablation, high-intensity focused ultrasound (HIFU), brachytherapy (for post-EBRT patients) and androgen deprivation therapy (ADT). ADT and salvage prostate cryoablation (SPC) are two commonly considered treatment options for RRPC. However, there is an urgent need for high-quality clinical studies to support evidence-based decisions on treatment choice. Our study aims to determine the feasibility of randomising men with RRPC for treatment with ADT and SPC. METHODS: The randomised controlled trial (CROP) was developed, which incorporated protocols to assess parameters relating to cryotherapy procedures and provide training workshops for optimising patient recruitment. Analysis of data from the recruitment phase and patient questionnaires was performed. RESULTS: Over a period of 18 months, 39 patients were screened for eligibility. Overall 28 patients were offered entry into the trial, but only 7 agreed to randomisation. The majority reason for declining entry into the trial was an unwillingness to be randomised into the study. 'Having the chance of getting cryotherapy' was the major reason for accepting the trial. Despite difficulty in retrieving cryotherapy temperature parameters from prior cases, 9 of 11 cryotherapy centres progressed through the Cryotherapists Qualification Process (CQP) and were approved for recruiting into the CROP study. CONCLUSIONS: Conveying equipoise between the two study arms for a salvage therapy was challenging. The use of delayed androgen therapy may have been seen as an inferior option. Future cohort studies into available salvage options (including prostate cryotherapy) for RRPC may be more acceptable to patients than randomisation within an RCT.

Mechanisms of cryoablation: clinical consequences on malignant tumors.

While the destructive actions of a cryoablative freeze cycle are long recognized, more recent evidence has revealed a complex set of molecular responses that provides a path for optimization. The importance of optimization relates to the observation that the cryosurgical treatment of tumors yields success only equivalent to alternative therapies. This is also true of all existing therapies of cancer, which while applied with curative intent; provide only disease suppression for periods ranging from months to years. Recent research has led to an important new understanding of the nature of cancer, which has implications for primary therapies, including cryosurgical treatment. We now recognize that a cancer is a highly organized tissue dependent on other supporting cells for its establishment, growth and invasion. Further, cancer stem cells are now recognized as an origin of disease and prove resistant to many treatment modalities. Growth is dependent on endothelial cells essential to blood vessel formation, fibroblasts production of growth factors, and protective functions of cells of the immune system. This review discusses the biology of cancer, which has profound implications for the diverse therapies of the disease, including cryosurgery. We also describe the cryosurgical treatment of diverse cancers, citing results, types of adjunctive therapy intended to improve clinical outcomes, and comment briefly on other energy-based ablative therapies. With an expanded view of tumor complexity we identify those elements key to effective cryoablation and strategies designed to optimize cancer cell mortality with a consideration of the now recognized hallmarks of cancer.

[Antibiotic prophylaxis in urology]. / Antibiotikaprophylaxe in der Urologie.

The aim of perioperative antibiotic prophylaxis is the prevention of surgical site infections and urinary tract infections during urological procedures. The indication for antibiotic prophylaxis comprises several risk factors such as the degree of contamination of the operative site, duration of surgery, implantation of devices and comorbidities of the individual patient. In general this involves a single antibiotic administration before the operative procedure. The antibiotic prophylaxis is part of the total antibiotic consumption and thus a factor contributing to emergence of antibiotic resistance. It is not a substitute for hygiene measures or operative precision.

Cryoablation of the prostate: technical recommendations.

The European Association of Urology guidelines on prostate cancer state that cryotherapy is a true therapeutic alternative for patients with clinically localized prostate cancer. The aim of this paper is to establish a uniform practice for performing prostate cryoablation. A collaboration has been set up among five European centres with experience in almost 1000 prostate cancer patients on the use of cryotherapy. The present recommendations were developed through sharing of experience and thorough discussions within the group. This first paper from the group establishes the technical recommendations for use of prostate cryotherapy.

[Cryosurgical ablation as primary treatment in prostate cancer patients]. / Crioterapia prostática como tratamiento primario en pacientes con cáncer de próstata.

OBJECTIVE: Cryosurgical ablation (CSA) is one treatment option that has been developed and it is now recognised as a true therapeutic alternative in the treatment of localised disease. The aim of this paper is to present the preliminary experience with CSA in prostate cancer from the centre in Norway. MATERIALS AND METHODS: A total of 132 patients with prostate cancer have been treated with CSA since September 2003. In 90 patients, CSA was the primary therapy used and these patients included those with low (LR; n=27), intermediate (IR; n=37) and high risk (HR: n=26) disease. Low risk patients were defined as those with T1a-T2a, NO, MO, Gleason score < or = 6 and prostate-specific antigen (PSA) <10 ng/ml. Intermediate risk were patients with T2b tumours or a PSA level of 10-20 ng/ml or Gleason score 7. High risk were defined as those with T2c tumours or Gleason score >7 or PSA >20 ng/ml. The remaining 42 patients either had locally advanced disease or had received salvage treatment after previous external beam radiation (EBRT), cryotherapy or hormone treatment. Patients were evaluated at 3 and 6 months and thereafter at 6 month intervals. A voiding history was taken and the following tests conducted: uroflowmetry, residual urine. RESULTS: Results are presented for those patients receiving CSA as a primary therapy. Currently, the longest follow-up period is 42 months. The median observation period is 21 months and 39% of patients have been seen at the 24-month follow-up visit. No evidence of clinical progression has been observed in patients in the LR or HR group. Two patients in the IR group had clinical evidence of progression. The most common side effects seen during the first year post CSA were urinary tract obstruction and the need for removal of dead prostatic tissue or calcifications. Histological examination of the removed tissue did not shown evidence of prostate cancer. All patients in the LR and IR group that were sexually active before treatment were also sexually active on last follow-up, 37% using some kind of aid. 86% of patients in the LR and IR groups reported no bother as to sexual function. CONCLUSIONS: CSA is now recognised by the EAU as a true therapeutic alternative for the treatment of prostate cancer. Many institutions offer CSA only to older patients due to the lack of long-term data. If longer follow-up data confirm the short-term effect seen in my series, and if comparable side effects are reported in other studies, CSA might also be offered as primary treatment to younger patients.

Crioterapia prostática como tratamiento primario en pacientes con cáncer de próstata / Cryosurgical ablation as primary treatment in prostate cancer patients

Objetivos: La ablación crioterápica prostática (CSA) es una de las opciones de tratamiento que se han desarrollado, siendo considerada, actualmente, como una alternativa terapéutica en la enfermedad localizada. El objetivo de este trabajo es presentar la experiencia preliminar con CSA en cáncer de próstata en un centro de Noruega. Material y Métodos. Un total de 132 pacientes con cáncer de próstata han sido tratados con CSA desde Septiembre de 2003. En 90 pacientes, la CSA fue utilizada como tratamiento primario. Estos pacientes presentaban enfermedad de bajo riesgo LR (n=27), riesgo intermedio IR (n=37) y alto riesgo HR (n=26). Los pacientes de bajo riesgo se definieron con las siguientes características: T1a-T2a, N0, M0, una puntuación de Gleason ≤ 6 y antígeno prostático específico de (PSA)7 o un PSA>20ng/ml. Los restantes 42 pacientes tenían enfermedad localmente avanzada o habían recibido tratamiento de rescate después de radioterapia externa (RTE), crioterapia o tratamiento hormonal. Los pacientes fueron evaluados a 3 y 6 meses y posteriormente a intervalos de 6 meses. Se realizó una historia funcional mediante flujometría y volumen residual. Resultados: Los resultados se presentan en aquellos pacientes que han recibido CSA como tratamiento primario, el seguimiento más largo es 42 meses. La mediana de seguimiento es de 21 meses y un 39% de los pacientes han sido vistos en la revisión de los 24 meses. No hay evidencia de progresión clínica en los pacientes en el grupo de bajo y alto riesgo (LH-RH). En el grupo de riego intermedio (IR) 2 pacientes evidenciaron progresión clínica. Los efectos secundarios más comunes durante el primer año post CSA fueron la obstrucción del tracto urinario y la necesidad de extirpar el tejido prostático necrosado o calcificado. El análisis histopatológico del tejido extraído no evidenció la presencia de cáncer de próstata. Todos los pacientes en los grupos de riesgo bajo e intermedio que eran sexualmente activos antes del tratamiento presentaban buena actividad sexual en el último seguimiento, 37% utilizaba algún tipo de ayuda. 86% de los pacientes de los grupos de riesgo bajo e intermedio no presentaron molestias en la esfera sexual. Conclusiones: La CSA está reconocida por la EAU, actualmente, como una alternativa terapéutica verdadera para el tratamiento del cáncer de próstata. Muchas instituciones ofrecen CSA sólo a pacientes ancianos debido a la ausencia de resultados a largo plazo. Si los resultados a largo plazo confirman los resultados obtenidos a corto plazo por mi serie, y si otras series obtienen efectos secundarios comparables, CSA podría ser ofrecido como tratamiento primario a pacientes jóvenes

Objective: Cryosurgical ablation (CSA) is one treatment option that has been developed and it is now recognised as a true therapeutic alternative in the treatment of localised disease. The aim of this paper is to present the preliminary experience with CSA in prostate cancer from the centre in Norway. Materials and methods: A total of 132 patients with prostate cancer have been treated with CSA since September 2003. In 90 patients, CSA was the primary therapy used and these patients included those with low (LR; n = 27), intermediate (IR; n = 37) and high risk (HR; n = 26) disease. Low risk patients were defined as those with T1a-T2a, N0, M0, Gleason score ≤ 6 and prostate-specific antigen (PSA) 7 or PSA > 20 ng/ml. The remaining 42 patients either had locally advanced disease or had received salvage treatment after previous external beam radiation (EBRT), cryotherapy or hormone treatment. Patients were evaluated at 3 and 6 months and thereafter at 6 month intervals. A voiding history was taken and the following tests conducted: uroflowmetry, residual urine. Results: Results are presented for those patients receiving CSA as a primary therapy. Currently, the longest follow-up period is 42 months. The median observation period is 21 months and 39% of patients have been seen at the 24-month follow-up visit. No evidence of clinical progression has been observed in patients in the LR or HR group. Two patients in the IR group had clinical evidence of progression. The most common side effects seen during the first year post CSA were urinary tract obstruction and the need for removal of dead prostatic tissue or calcifications. Histological examination of the removed tissue did not shown evidence of prostate cancer. All patients in the LR and IR group that were sexually active before treatment were also sexually active on last follow-up, 37% using some kind of aid. 86% of patients in the LR and IR groups reported no bother as to sexual function. Conclusions: CSA is now recognised by the EAU as a true therapeutic alternative for the treatment of prostate cancer. Many institutions offer CSA only to older patients due to the lack of long-term data. If longer follow-up data confirm the short-term effect seen in my series, and if comparable side effects are reported in other studies, CSA might also be offered as primary treatment to younger patients

Acute renal failure following IVF: case report.

IVF is one of the most comprehensively registered interventions in clinical medicine. IVF is regarded as safe with very few complications. We report a woman who developed acute renal failure due to compression of both ureters from enlarged stimulated ovaries. The condition was diagnosed using ultrasound and magnetic resonance imaging (MRI). The condition was treated with insertion of double-J stents in both ureters and resolved without need of dialysis. Compression of the ureters due to enlarged ovaries should be considered if a patient develops acute renal failure following IVF.

Evaluation of Tet-on system to avoid transgene down-regulation in ex vivo gene transfer to the CNS.

Ex vivo gene transfer to the CNS has so far been hampered by instability of transgene expression. To avoid the phenomenon of transgene down-regulation, we have employed strong, constitutive promoters and compared this expression system with the inducible Tet expression system incorporated in a single plasmid vector or in lentiviral vectors. Plasmid-based transgene expression directed by the constitutive, human ubiquitin promoter, UbC, was stable in transfected HiB5 cells in vitro and comparable in strength to the CMV promoter. However, after transplantation of UbC and CMV HiB5 clones to the rat striatum, silencing of the transgene occurred in most cells soon after implantation of transfected cells. The Tet-on elements were incorporated in a single plasmid vector and inducible HiB5 clones were generated. Inducible clones displayed varying basal expression activity, which could not be ascribed to an effect of cis-elements in the vector, but rather was due, at least in part, to intrinsic activity of the minimal promoter. Basal expression activity could be blocked in a majority of cells by stable expressing the transrepressor tTS. Fully induced expression levels were comparable to CMV and UbC promoters. Similar to the constitutive promoters transgene expression was down-regulated soon after grafting of inducible HiB5 clones to the rat striatum. Lentiviral vectors can direct long-term stable in vivo transgene expression. To take advantage of this quality of the lentiviral vector, the Tet-on elements were incorporated in two lentiviral transfer vectors followed by transduction of Hib5 cells. Interestingly, all HiB5 clones established by lentiviral transduction showed very similar expression patterns and tight regulatability that apparently was independent of transgene copy number and integration site. Nevertheless, transgene expression in all lentiviral HiB5 clones was down-regulated shortly after transplantation to the rat striatum. These results confirm the general phenomenon of transgene down-regulation. Moreover, the results suggest that the considerable advantages offered by lentiviral vectors for direct gene delivery cannot necessarily be transferred directly to ex vivo gene delivery. This emphasizes the need for alternative vector strategies for ex vivo gene transfer.

EAU guidelines for the management of urinary and male genital tract infections. Urinary Tract Infection (UTI) Working Group of the Health Care Office (HCO) of the European Association of Urology (EAU).

A short version of the UTI Guidelines elaborated by the Urinary Tract Infection Working Group of the Health Care Office of the European Association of Urology is presented. The topics include classification, diagnosis, treatment and follow-up of uncomplicated UTI, UTI in children, UTI in diabetes mellitus, renal insufficiency, renal transplant recipients and immunosuppression, complicated UTI due to urological disorders, sepsis syndrome, urosepsis, urethritis, prostatitis, epididymitis, orchitis and principles of perioperative prophylaxis in urology.

Positive and negative interactions of GDNF, NTN and ART in developing sensory neuron subpopulations, and their collaboration with neurotrophins.

Glial cell line-derived neurotrophic factor (GDNF), neurturin (NTN) and neublastin/artemin (ART) are distant members of the transforming growth factor beta family, and have been shown to elicit neurotrophic effects upon several classes of peripheral and central neurons. Limited information from in vitro and expression studies has also substantiated a role for GDNF family ligands in mammalian somatosensory neuron development. Here, we show that although dorsal root ganglion (DRG) sensory neurons express GDNF family receptors embryonically, they do not survive in response to their ligands. The regulation of survival emerges postnatally for all GDNF family ligands. GDNF and NTN support distinct subpopulations that can be separated with respect to their expression of GDNF family receptors, whereas ART supports neurons in populations that are also responsive to GDNF or NTN. Sensory neurons that coexpress GDNF family receptors are medium sized, whereas small-caliber nociceptive cells preferentially express a single receptor. In contrast to brain-derived neurotrophic factor (BDNF)-dependent neurons, embryonic nerve growth factor (NGF)-dependent nociceptive neurons switch dependency to GDNF, NTN and ART postnatally. Neurons that survive in the presence of neurotrophin 3 (NT3) or neurotrophin 4 (NT4), including proprioceptive afferents, Merkel end organs and D-hair afferents, are also supported by GDNF family ligands neonatally, although at postnatal stages they lose their dependency on GDNF and NTN. At late postnatal stages, ART prevents survival elicited by GDNF and NTN. These data provide new insights on the roles of GDNF family ligands in sensory neuron development.

Improved survival of embryonic porcine dopaminergic neurons in coculture with a conditionally immortalized GDNF-producing hippocampal cell line.

Transplantation of embryonic nigral tissue is used as an experimental therapy for patients with Parkinson's disease but is hampered by a limited survival rate of dopaminergic neurons. Glial cell line-derived neurotrophic factor (GDNF) is a potent survival factor for nigrostriatal dopaminergic neurons, and the present in vitro study aimed at improving the survival of dopaminergic neurons in porcine mesencephalic brain slice cultures by adding transfected, immortalized, temperature-sensitive GDNF-releasing HiB5 cells (HiB5-GDNF). Embryonic (E27/28) porcine ventral mesencephalic brain slices were placed on membrane inserts in six-well plates with serum-containing medium, and HiB5-GDNF, nontransfected HiB5 cells (HiB5-control), or green fluorescent protein-producing HiB5 cells (HiB5-GFP) were seeded onto each tissue slice. The concentration of GDNF in the coculture medium was 0.49 +/- 0.13 ng/ml at day 9 and 0. 22 +/- 0.05 ng/ml at day 19 (mean +/- SEM) as measured by GDNF ELISA. The decrease in release of GDNF over time was paralleled by a gradual reduction in the number of HiB5-GFP cells expressing the reporter gene (EGFP). At day 12, HPLC analysis revealed that medium from HiB5-GDNF cocultures contained 2.0 times more dopamine than medium from HiB5-control cocultures. At day 21 there was 1.6 times more dopamine. Similar results were obtained for the dopamine metabolite 3,4-dihydroxyphenylacetic acid. At day 21, cell counts showed that HiB5-GDNF cocultures contained 1.5 times more tyrosine hydroxylase immunoreactive neurons than HiB5-control cocultures, which must be compared with a 1.8 fold increase after chronic treatment with rhGDNF (10 ng/ml). In conclusion, the better survival of HiB5-GDNF cocultures is promising for the generation of effective cell lines for local delivery of neurotrophic factors to intracerebral nigral grafts.

The DaNeX study of embryonic mesencephalic, dopaminergic tissue grafted to a minipig model of Parkinson's disease: preliminary findings of effect of MPTP poisoning on striatal dopaminergic markers.

A multicenter study is under way to investigate the efficacy of allografting of embryonic mesencephalic neurons in a pig model of Parkinson's disease. We have first established that a stable parkinsonian syndrome can be established by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) intoxication of adult male Göttingen minipigs. We are now using positron emission tomography (PET) methods for testing the physiological responses to MPTP intoxication and the time course of the response to several treatment strategies. We now report preliminary results obtained in 11 pigs employed in the initial phase of the study; the completed study shall ultimately include 30 pigs. Animals were randomly assigned to one of five groups: 1) Control, 2) MPTP intoxication, 3) MPTP intoxication followed by allograft, 4) MPTP intoxication followed by allograft with immunosuppression, and 5) MPTP intoxication followed by allograft with immunosuppression and co-grafting of immortalized HiB5 cells, which had been manipulated to secrete glia cell line-derived neurotrophic factor (GDNF) (approximately 2 ng GDNF/h/10(5) cells). MPTP was administered (1 mg/kg/day, SC) for 7-10 days until the pigs had developed mild parkinsonian symptoms of muscle rigidity, hypokinesia, and impaired coordination, especially of the hind limbs. Approximately 2 weeks after the last MPTP dose, animals received a T1-weighted magnetic resonance imaging (MRI) scan, and a series of dynamic PET recordings. After the first series of PET scans, four grafts of porcine embryonic mesencephalic tissue (E28 days) were placed in each striatum of some MPTP-intoxicated pigs, using MRI-based stereotactic techniques. Immunosuppression of some animals with cyclosporin and prednisolone began just prior to surgery. Two more series of PET scans were performed at 4-month intervals after surgery. After the last scans, pigs were killed and the brains were perfused for unbiased stereological examination of cytological and histochemical markers in striatum and substantial nigra. The behavioral impairment of the animals (the "Parkinson's score") had been evaluated throughout the 8-month period. Kinetic analysis of the first set of PET scans has indicated that the rate constant for the decarboxylation of FDOPA in catecholamine fibers was reduced by 33% in striatum of the mildly parkinsonian pigs. The rate of association of [11C]NS-2214 to catecholamine uptake sites was reduced by 62% in the same groups of pigs. No significant difference was found in the binding potential of [11C]raclopride to the dopamine D2-like receptors in striatum of the MPTP-intoxicated versus control pigs. These preliminary results are suggestive that the activity of DOPA decarboxylase may be upregulated in the partially denervated pig striatum.

In vivo protection of nigral dopamine neurons by lentiviral gene transfer of the novel GDNF-family member neublastin/artemin.

The glial cell line-derived neurotrophic factor (GDNF)-family of neurotrophic factors consisted until recently of three members, GDNF, neurturin, and persephin. We describe here the cloning of a new GDNF-family member, neublastin (NBN), identical to artemin (ART), recently published (Baloh et al., 1998). Addition of NBN/ART to cultures of fetal mesencephalic dopamine (DA) neurons increased the number of surviving tyrosine hydroxylase (TH)-immunoreactive neurons by approximately 70%, similar to the maximal effect obtained with GDNF. To investigate the neuroprotective effects in vivo, lentiviral vectors carrying the cDNA for NBN/ART or GDNF were injected into the striatum and ventral midbrain. Three weeks after an intrastriatal 6-hydroxydopamine lesion only about 20% of the nigral DA neurons were left in the control group, while 80-90% of the DA neurons remained in the NBN/ART and GDNF treatment groups, and the striatal TH-immunoreactive innervation was partly spared. We conclude that NBN/ART, similarly to GDNF, is a potent neuroprotective factor for the nigrostriatal DA neurons in vivo.

GDNF and neublastin protect against NMDA-induced excitotoxicity in hippocampal slice cultures.

The potential neuroprotective effects of glial cell line-derived neurotrophic factor (GDNF) and neublastin (NBN) against NMDA-induced excitotoxicity were examined in hippocampal brain slice cultures. Recombinant human GDNF (25-100 ng/ ml) or NBN, in medium conditioned by growth of transfected, NBN-producing HiB5 cells, were added to slice cultures I h before exposure to 10 microM NMDA for 48h. Neuronal cell death was monitored, before and during the NMDA exposure, by densitometric measurements of propidium iodide (PI) uptake and loss of Nissl staining. Both the addition of rhGDNF and NBN-containing medium significantly reduced the NMDA-induced PI uptake in the CA1 (p < 0.01), suggesting neuroprotective effects of these factors, beyond their well-known trophic effects on dopaminergic neurons.

Cellular processing of the amyloidogenic cystatin C variant of hereditary cerebral hemorrhage with amyloidosis, Icelandic type.

An important gap in our understanding of the pathogenesis of the amyloidoses is the identification of the cellular events that lead from synthesis of an amyloid precursor protein to its conversion to the amyloid fiber subunit. We address this question by characterizing the effects of an amyloidogenic mutation on the intracellular processing of its protein product. The protein, a mutant of the cysteine protease inhibitor cystatin C, is the amyloid precursor protein in Hereditary Cerebral Hemorrhage with Amyloidosis--Icelandic type (HCHWA-I). The amyloid fibers are composed of mutant cystatin C (L68Q) that lacks the first 10 amino acids. We have previously shown that processing of wild-type cystatin C entails formation of a transient intracellular dimer that dissociates prior to secretion, such that extracellular cystatin C is monomeric. We report here that the cystatin C mutation engenders several alterations in its intracellular trafficking. It forms a stable intracellular dimer that is partially retained in the endoplasmic reticulum and degraded. The bulk of mutant cystatin C that is secreted does not dissociate and is secreted as an inactive dimer. Thus, formation of the stable mutant cystatin C dimer is an early event in the pathogenesis of this disease.