Plexin-B1 Mutation Drives Metastasis in Prostate Cancer Mouse Models

Metastatic prostate cancer is essentially incurable and is a leading cause of cancer-related morbidity and mortality in men, yet the underlying molecular mechanisms are poorly understood. Plexins are transmembrane receptors for semaphorins with divergent roles in many forms of cancer. We show here that prostate epithelial cell-specific expression of a mutant form of Plexin-B1 (P1597L) which was identified in metastatic deposits in patients with prostate cancer, significantly increases metastasis, in particular metastasis to distant sites, in two transgenic mouse models of prostate cancer (PbCre⁺Pten^{fl /fl}Kras^G12V and PbCre⁺Pten^{fl /fl}p53^{fl/ fl} ). In contrast, prostate epithelial cell-specific expression of wild-type (WT) Plexin-B1 in PbCre⁺Pten^{fl /fl}Kras^G12V mice significantly decreases metastasis, showing that a single clinically relevant Pro1597Leu amino-acid change converts Plexin-B1 from a metastasis-suppressor to a metastasis-promoter. Furthermore, PLXNB1^P1597L significantly increased invasion of tumor cells into the prostate stroma, while PLXNB1^WT reduced invasion, suggesting that Plexin-B1 has a role in the initial stages of metastasis. Deletion of RhoA/C or PDZRhoGEF in Pten^{fl /fl}Kras^G12VPLXNB1^P1597L mice suppressed metastasis, implicating the Rho/ROCK pathway in this phenotypic switch. Germline deletion of Plexin-B1, to model anti-Plexin-B1 therapy, significantly decreased invasion and metastasis in both models. Our results demonstrate that Plexin-B1 plays a complex yet significant role in metastasis in mouse models of prostate cancer and is a potential therapeutic target to block the lethal spread of the disease.

Significance

Few therapeutic targets have been identified specifically for preventing locally invasive/oligometastatic prostate cancer from becoming more widely disseminated. Our findings suggest Plexin-B1 signaling, particularly from the clinically relevant P1597L mutant, is such a target.

Focal segmental glomerulosclerosis and mild intellectual disability in a patient with a novel de novo truncating TRIM8 mutation

Mutations in the TRIM8 gene have been described in patients with severe developmental delay, intellectual disability and epilepsy. Only six patients have been described to date. All the previous mutations were truncating variants clustered in the C-terminus of the protein. A previous patient with TRIM8-related epileptic encephalopathy was reported to have nephrotic syndrome. Here we describe the clinical, radiological and histological features of an 8-year-old male patient with a TRIM8 mutation who, in contrast to previous patients, had only mild intellectual disability and well-controlled epilepsy. The patient was found to have proteinuria at 2 years of age. Renal biopsy findings were suggestive of focal segmental glomerulosclerosis. His kidney function declined and peritoneal dialysis was started at 5 years of age. He underwent renal transplant at 7 years of age. Trio-based whole genome sequencing identified a novel de novo heterozygous frameshift mutation in TRIM8 (NM_030912.2) c.1198_1220del, p.(Tyr400ArgfsTer2). This patient is further evidence that TRIM8 mutations cause a syndrome with both neurological and renal features. Our findings suggest the spectrum of TRIM8-related disease may be wider than previously thought with the possibility of milder neurodevelopmental problems and/or a more severe, progressive renal phenotype. We highlight the need for proteinuria screening in patients with TRIM8 mutations.

The ProtecT trial: analysis of the patient cohort, baseline risk stratification and disease progression

OBJECTIVE

To test the hypothesis that the baseline clinico-pathological features of the men with localized prostate cancer (PCa) included in the ProtecT (Prostate Testing for Cancer and Treatment) trial who progressed (n = 198) at a 10-year median follow-up were different from those of men with stable disease (n = 1409).

PATIENTS AND METHODS

We stratified the study participants at baseline according to risk of progression using clinical disease stage, pathological grade and PSA level, using Cox proportional hazard models.

RESULTS

The findings showed that 34% of participants (n = 505) had intermediate- or high-risk PCa, and 66% (n = 973) had low-risk PCa. Of 198 participants who progressed, 101 (51%) had baseline International Society of Urological Pathology Grade Group 1, 59 (30%) Grade Group 2, and 38 (19%) Grade Group 3 PCa, compared with 79%, 17% and 5%, respectively, for 1409 participants without progression (P < 0.001). In participants with progression, 38% and 62% had baseline low- and intermediate-/high-risk disease, compared with 69% and 31% of participants with stable disease (P < 0.001). Treatment received, age (65-69 vs 50-64 years), PSA level, Grade Group, clinical stage, risk group, number of positive cores, tumour length and perineural invasion were associated with time to progression (P ≤ 0.005). Men progressing after surgery (n = 19) were more likely to have a higher Grade Group and pathological stage at surgery, larger tumours, lymph node involvement and positive margins.

CONCLUSIONS

We demonstrate that one-third of the ProtecT cohort consists of people with intermediate-/high-risk disease, and the outcomes data at an average of 10 years' follow-up are generalizable beyond men with low-risk PCa.

Data set for the reporting of carcinoma of renal tubular origin: recommendations from the International Collaboration on Cancer Reporting (ICCR)

AIMS

The International Collaboration on Cancer Reporting (ICCR) has provided detailed data sets based upon the published reporting protocols of the Royal College of Pathologists, the Royal College of Pathologists of Australasia and the College of American Pathologists.

METHODS AND RESULTS

The data set for carcinomas of renal tubular origin treated by nephrectomy was developed to provide a minimum structured reporting template suitable for international use, and incorporated recommendations from the 2012 Vancouver Consensus Conference of the International Society of Urological Pathology (ISUP) and the fourth edition of the World Health Organisation Bluebook on tumours of the urinary and male genital systems published in 2016. Reporting elements were divided into those, which are required and recommended components of the report. Required elements are: specimen laterality, operative procedure, attached structures, tumour focality, tumour dimension, tumour type, WHO/ISUP grade, sarcomatoid/rhabdoid morphology, tumour necrosis, extent of invasion, lymph node status, surgical margin status, AJCC TNM staging and co-existing pathology. Recommended reporting elements are: pre-operative treatment, details of tissue removed for experimental purposes prior to submission, site of tumour(s) block identification key, extent of sarcomatoid and/or rhabdoid component, extent of necrosis, presence of tumour in renal vein wall, lymphovascular invasion and lymph node status (size of largest focus and extranodal extension).

CONCLUSIONS

It is anticipated that the implementation of this data set in routine clinical practice will inform patient treatment as well as provide standardised information relating to outcome prediction. The harmonisation of data reporting should also facilitate international research collaborations.

International Society of Urological Pathology (ISUP) Consensus Conference on Handling and Staging of Radical Prostatectomy Specimens. Working group 4: seminal vesicles and lymph nodes

The 2009 International Society of Urological Pathology Consensus Conference in Boston made recommendations regarding the standardization of pathology reporting of radical prostatectomy specimens. Issues relating to the infiltration of tumor into the seminal vesicles and regional lymph nodes were coordinated by working group 4. There was a consensus that complete blocking of the seminal vesicles was not necessary, although sampling of the junction of the seminal vesicles and prostate was mandatory. There was consensus that sampling of the vas deferens margins was not obligatory. There was also consensus that muscular wall invasion of the extraprostatic seminal vesicle only should be regarded as seminal vesicle invasion. Categorization into types of seminal vesicle spread was agreed by consensus to be not necessary. For examination of lymph nodes, there was consensus that special techniques such as frozen sectioning were of use only in high-risk cases. There was no consensus on the optimal sampling method for pelvic lymph node dissection specimens, although there was consensus that all lymph nodes should be completely blocked as a minimum. There was also a consensus that a count of the number of lymph nodes harvested should be attempted. In view of recent evidence, there was consensus that the diameter of the largest lymph node metastasis should be measured. These consensus decisions will hopefully clarify the difficult areas of pathological assessment in radical prostatectomy evaluation and improve the concordance of research series to allow more accurate assessment of patient prognosis.

Adult day-case renal biopsy: a single-centre experience

BACKGROUND

Despite improvements in safety seen over the last 20 years, percutaneous renal biopsy is still associated with haemorrhagic complications. Due to concerns over delayed bleeding, most nephrologists would advocate overnight observation. Recent evidence in both adult and paediatric populations suggest that in some groups, this is unnecessary. Since 1991, we have provided a day-case renal biopsy service performing 70 such procedures per year. In this study, we present a retrospective analysis of this practice.

METHODS

A total of 192 patients over a consecutive 3-year period were analysed retrospectively. Patients were selected according to standardized criteria, and biopsy was performed using a modern technique (automated biopsy needles under ultrasound guidance). Complications were identified by examination of case notes and local hospital admission databases, and by telephone interview. Our pathology database was examined for sample adequacy and diagnosis.

RESULTS

There were no delayed complications in the study group with 187 patients (97.4%) being discharged home on the same day. Major complications occurred in five patients (2.6%), all related to bleeding. Of these, two needed radiological intervention to achieve haemostasis. Sufficient tissue for diagnosis was achieved in 97% of cases, with a mean of 47 ± 23 glomeruli obtained per patient. Most biopsies were obtained with ≤ 2 passes (84%).

CONCLUSIONS

Our findings show that in selected adult patients, renal biopsy can be performed as a day-case procedure. Given the benefits of day-case strategies in terms of patient and healthcare costs, we advocate increased utilization of this technique.

The European Network of Uropathology: a novel mechanism for communication between pathologists

In pathology there is a need to rapidly disseminate professional information to the appropriate target groups. This is a surprisingly difficult task on an international level. Therefore, the European Network of Uropathology (ENUP) was recently organized by the Uropathology Working Group of the European Society of Pathology. The purposes were to establish a channel for distribution of information about uropathology, such as guidelines, consensus documents, meetings and courses; to organize research collaborations; and to set up mechanisms for survey studies. ENUP has recruited a total of 374 individual members from 338 pathology laboratories in 15 Western European countries. E-mail is used for all communication, and studies are carried out through interactive Web sites. Information e-mails are sent regularly, and 2 Web-based surveys on handling and reporting of urologic specimens have been conducted. Here we report on the methods used to organize this novel information network. We think that ENUP could serve as a model for other fields of pathology and other geographic regions.

Handling and reporting of radical prostatectomy specimens in Europe: a web-based survey by the European Network of Uropathology (ENUP)

AIMS

To survey current European practices in handling and reporting of radical prostatectomy (RP) specimens.

METHODS AND RESULTS

A European Network of Uropathology (ENUP) was organized for the dissemination of information, survey studies and research collaborations. Contact data of uropathologists were collected from 321 pathology laboratories in 15 West European countries. In the first ENUP survey, 67.6% (217/321) of the members replied to a web-based questionnaire. Some practices were adopted by a large majority, e.g. inking of the specimen (96.6%), Gleason grading (99.5%), stratifying extraprostatic extension (EPE) according to extent (88.2%), reporting TNM stage (88.6%) and reporting location of positive margins (98%). As many as 71.6% of respondents always embedded the entire prostate and only 10.8% always practised partial embedding. Whole mounts were routinely used by 37.5% and standard blocks by 55.5%. Among areas with variable routines were methods to define focal versus extensive EPE and methods to quantify margin positivity, probably reflecting that the optimal method has yet to be determined.

CONCLUSIONS

Some practices are almost universally adopted in Europe, whereas others still need to be standardized. The results of the study may be helpful when judging what recommendations are reasonable to issue.

Mcm2, Geminin, and KI67 define proliferative state and are prognostic markers in renal cell carcinoma

PURPOSE

The origin licensing factors minichromosome maintenance 2 (Mcm2) and Geminin have recently been identified as critical regulators of growth and differentiation. Here we have investigated the regulation of these licensing factors together with Ki67 to further elucidate the cell cycle kinetics of renal cell carcinoma (RCC). Furthermore, we have examined the role of Ki67, Mcm2, and Geminin in disease-free survival after nephrectomy in patients with localized RCC.

EXPERIMENTAL DESIGN

Tissue sections from 176 radical nephrectomy specimens were immunohistochemically stained with Mcm2, Geminin, and Ki67 antibodies. Labeling indices (LI) for these markers were compared with clinicopathologic parameters (median follow-up 44 months).

RESULTS

In RCC, Mcm2 is expressed at much higher levels than Ki-67 and Geminin, respectively [medians 41.6%, 7.3%, and 3.5% (P < 0.001)] and was most closely linked to tumor grade (P < 0.001). For each marker, Kaplan-Meier survival curves provided strong evidence that increased expression is associated with reduced disease-free survival time (P < 0.001). Additionally, an Mcm2-Ki67 LI identified a unique licensed but nonproliferating population of tumor cells that increased significantly with tumor grade (P = 0.004) and was also of prognostic value (P = 0.01). On multivariate analysis, grade, vascular invasion, capsular invasion, Ki67 LI >12%, and age were found to be independent prognostic markers.

CONCLUSIONS

Although Ki67 is identified as an independent prognostic marker, semiquantitative assessment is difficult due to the very low proliferative fraction identified by this marker. In contrast, Mcm2 identifies an increased growth fraction that is closely linked to grade, provides prognostic information, and is amenable to semiquantitative analysis in routine pathologic assessment.

Effects of a selective adenosine A1 receptor antagonist on the development of cyclosporin nephrotoxicity

1. The clinical application of cyclosporin as an immunosuppressive agent is limited by its nephrotoxicity. 2. The effect of FK453, a selective A1-receptor antagonist, administered twice daily to rats at a dose of 100 mg kg-1 was assessed on the development of nephrotoxicity induced by cyclosporin (10 mg kg-1 i.p. daily) administered for 14 days. The effects of nifedipine administered twice daily (0.3 mg kg-1 s.c.) for 14 days, on cyclosporin nephrotoxicity were also studied. 3. Cyclosporin induced a 46.58% and 35.78% decline in glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) respectively and a reduction of 16.69% in filtration fraction (FF). Co-administration of FK453 resulted in falls of 30.5%, 18.59% and 14.7% in GFR, ERPF and FF respectively, the former two significantly less than the falls seen with cyclosporin (CyA) alone (P < 0.05 vs CyA, ANOVA). 4. Nifedipine appeared to have a more pronounced protective effect resulting in a decline of only 20.91% in GFR, with no significant change in ERPF (increase of 0.93%) when co-administered with CyA. 5. These observations indicate adenosine plays a minor role in the pathophysiology of CyA nephrotoxicity.

Permselectivity in thin membrane nephropathy

The glomerular permselectivity to polydisperse neutral dextrans was compared in 6 patients with thin membrane nephropathy (TMN) and 10 healthy controls. Despite having normal renal hemodynamics and minimal proteinuria, the patients with TMN had significantly increased fractional clearance of neutral molecules with Stokes radius > 42 A. Conventional theories of glomerular barrier size selectivity cannot fully explain these data since they would predict that our patients would have had nephrotic range proteinuria.

Quantitative audit of the content of histopathology reports

An audit of histopathology reports presents the problem that the output is textual and difficult to quantify. This makes the definition of an adequate report subjective and susceptible to observer variation. A procedure has been developed which allows the quantitative analysis of reports and facilitates the development of local reporting guidelines. A topic is selected; the auditor then lists the possible details that may be included in the report and notes how many reports from a sample include each detail. The results are discussed at a departmental meeting with the aim of agreeing on reporting guidelines. At a later date another sample of reports can be analysed for compliance with the guidelines and compared with the previous reports. Problems with compliance can be discussed further and at the audit meeting the guidelines may be amended appropriately, thus completing the audit cycle. This method of audit has the advantage that the results are quantitative and that the group discussion and re-examination of the guidelines has educational value.

Renal transplant sonography: correlation of Doppler and biopsy results in cellular rejection

Seventy-one patients with allograft dysfunction had concomitant Doppler sonography and percutaneous biopsy. Forty-one had biopsy proven acute cellular rejection and eight had acute cellular rejection in combination with acute tubular necrosis. Real time ultrasonic appearance and various parameters of Doppler waveform were studied and compared with 30 controls who had a long period of stable function with no previous episodes of rejection or acute tubular necrosis (ATN). Morphological appearances were unhelpful in diagnosing rejection. A resistive index greater than 0.8 in the study group was highly specific for dysfunction but could not differentiate between acute rejection and ATN. However, two patients in the control group of normal transplants had a resistive index of 0.83. An early to mid diastolic notch was highly specific for acute rejection but of low sensitivity. It may be the only Doppler indication of cellular rejection and may be present when the resistive index is in the normal range.

Selective IgA deficiency associated with glomerulonephritis and oligoarthritis

A 59 year old woman with selective IgA deficiency associated with oligoarthritis and glomerulonephritis is described. She was seropositive for rheumatoid factor and renal histological examination showed a focal glomerulonephritis. High titre rheumatoid factor and a focal glomerulonephritis were also present in the only other well documented report of selective IgA deficiency and renal disease. Histological examination of the kidney suggested that the glomerulonephritis was mediated by immune complexes.

Rationalisation of follow-up in patients with non-invasive bladder tumours. A preliminary report

The risk of recurrence and progression in 170 patients presenting with pTa urothelial tumours of the bladder has been estimated so that follow-up can be rationalised. Patients were followed up for between 1 and 15 years, the original pathology reviewed and those with carcinoma in situ (CIS) or dysplasia of the background urothelium excluded. Only 5 patients progressed over the whole follow-up period, giving an overall progression rate of 3%. Solitary tumours had an annual initial recurrence risk (AIR) of 0.23 in the first year; after the first year the AIR fell to approximately 0.1 but did not fall significantly in subsequent years up to 8 years. Of the 45 patients with multiple tumours, 32 suffered recurrences within the first year (AIR 0.71). Tumour grade did not influence either recurrence or progression. The results indicate that for solitary pTa tumours, less frequent endoscopic follow-up is justified but some continued surveillance after 5 disease-free years is necessary. The estimated risk of recurrence is a useful factor to consider when planning follow-up.

Acute retention of urine and hypogonadism in a man

We report on a man with castrate levels of testosterone who had acute retention of urine secondary to prostatic obstruction.

Duplex Doppler ultrasound in the diagnosis of acute renal allograft rejection

As renal transplantation becomes more commonplace and successful, there is an increasing demand for non-invasive methods of studying possible complications. One hundred and fifty-four duplex Doppler sonography scans were performed in 38 patients within 52 days of receiving a renal allograft. Renal vascular impedance was estimated in the intrarenal arteries by calculating the resistive index ([peak systolic frequency shift--lowest diastolic frequency shift]/peak systolic frequency shift). A resistive index of greater than 0.80 was very suggestive of rejection (positive predictive value 82%); with a value of less than 0.70 rejection was unlikely (negative predictive value, 98%).

The morphological and immunohistochemical analysis of renal biopsies by light and electron microscopy using a single processing method

A methodology is described in which a number of well-established research techniques are brought together to enable the complete diagnostic analysis of a renal biopsy on a single piece of tissue. By embedding the biopsy in the acrylic resin LR White, unsupported sections of which are stable in the electron beam, light and electron microscopy and immunocytochemistry become feasible on sections from the same block. The biopsy is glutaraldehyde fixed but post-fixation in osmium tetroxide, which is often deleterious to antigen preservation, is omitted. Extraction in organic solvents and resin monomer is minimized by rapidly infiltrating the tissue from 70% ethanol and polymerizing the resin catalytically at 0 degrees C. Semithin sections can be stained with haematoxylin and eosin, Toluidine Blue or methenamine silver, giving results similar or superior to those obtained from paraffin sections. Thin sections show that the standard of morphological preservation is similar to that seen using epoxide sections even though the kidney is unosmicated. The tissue retains a high level of antigen reactivity, which, in the limited number of cases so far examined, has paralleled or exceeded that demonstrated by conventional immunofluorescence on frozen sections.

The clonal origin of experimental large bowel tumours

Images

Demonstration of somatic mutation and colonic crypt clonality by X-linked enzyme histochemistry

Cellular mosaicism resulting from X-chromosome inactivation in heterozygous females can be shown histochemically; using this approach we have demonstrated age-related gene reactivation and tumour clonality. We now show in female mice heterozygous for reduced expression of glucose-6-phosphate dehydrogenase (G6PD) activity that colonic epithelial cells express either normal or low enzyme activity, and form patches composed of multiple crypts of uniform phenotype. We also show that a low-enzyme colonic epithelial cell phenotype can be induced in normal mice by carcinogen treatment, these cells again occur in patches, but are restricted to scattered single crypts, the frequency of which is related to treatment. A small proportion of colonic tumours in carcinogen treated normal mice are also of low-enzyme phenotype. We conclude that we have visualized the effects of a sporadic carcinogen induced somatic mutation in the G6PD gene of crypt stem cells and that a single stem cell maintains each colonic crypt. This inducible defective activity of a ubiquitous 'housekeeping' enzyme provides a somatic clonal marker system of wide potential application.

Duodenal carcinoid tumours, phaeochromocytoma and neurofibromatosis: islet cell tumour, phaeochromocytoma and the von Hippel-Lindau complex: two distinctive neuroendocrine syndromes

To clarify neuroendocrine syndromes we have reviewed the association of neurofibromatosis with carcinoid tumours and of neurofibromatosis, phaeochromocytoma or von Hippel-Lindau complex with either carcinoid or islet cell tumours. In nine cases of neurofibromatosis with a carcinoid tumour studied all carcinoid tumours were in the duodenum, were distinctive histologically and had widespread somatostatin immunoreactivity. The duodenum was the primary site in 18 of 20 further published cases of carcinoid tumour and neurofibromatosis. Phaeochromocytoma was also present in six of these 27 cases with neurofibromatosis and duodenal carcinoid tumour. Six patients have been reported with Von Hippel-Lindau complex, phaeochromocytoma and islet cell tumour. A further 11 patients showed phaeochromocytoma and islet cell tumour. No cases of Von Hippel-Lindau complex had a carcinoid tumour, and no cases of neurofibromatosis had an islet cell tumour. We conclude that the association of neurofibromatosis, duodenal carcinoid tumour and phaeochromocytoma forms a distinctive neuroendocrine syndrome, sharply separated from the association of Von Hippel-Lindau complex with islet cell tumour and phaeochromocytoma. This separation is important in pathogenesis, diagnosis and clinical management.

Glandular duodenal carcinoid--a somatostatin rich tumour with neuroendocrine associations

The clinical and pathological features of four cases of duodenal carcinoid tumour are presented. All four tumours showed a glandular pattern, and in three cases this was associated with psammoma bodies. In three tumours somatostatin was identified by immunocytochemistry in most tumour cells. In two cases the duodenal tumours were associated with von Recklinghausen's disease and phaeochromocytoma. The importance of these unusual features is discussed, and it is suggested that these glandular carcinoids are a specific subgroup of endocrine cell tumours which appear to have potentially important clinical and pathological associations.

Multiple endocrine neoplasia associated with von Recklinghausen's disease

Details were studied of three patients with duodenal carcinoid tumour in association with neurofibromatosis and phaeochromocytoma, and of four patients with duodenal carcinoid and either von Recklinghausen's disease or phaeochromocytoma. The rarity of these endocrine tumours, together with the unusual morphological features and somatostatin content of the two duodenal carcinoids examined, suggest that this combination of tumours is not a chance association. It is suggested that this linkage of neurofibromatosis, phaeochromocytoma, and duodenal carcinoid is a specific multiple endocrine neoplasia syndrome.