Molecular Analysis of Upper Tract and Bladder Urothelial Carcinoma: Results from a Microarray Comparison

Introduction

Prior studies have shown genetic similarities between upper tract and bladder urothelial carcinoma. However, upper tract urothelial carcinoma tends to be higher grade than bladder urothelial carcinoma and tends to form in patients with certain familial conditions (e.g. Lynch Syndrome), indicating there may be unique biologic processes in these tumors. The purpose of this study was to evaluate the differences in gene expression between upper tract and bladder urothelial carcinoma using microarray data.

Design, Setting, Participants

A search of publicly available microarray datasets identified a clinically annotated dataset of 12 upper tract and 20 bladder urothelial carcinoma specimens. Gene expression analysis of data derived from the Affymetrix HGU133Plus2 chip was performed. Bioconductor packages were used to evaluate clustering, differential gene expression, pathways relevant to oncology, and a basal/luminal signature in upper tract versus bladder urothelial carcinoma.

Results

When separated by pathologic T stage, there was evidence of differential clustering among pT3 tumors and significant gene expression differences in 81 genes. Pathway analysis revealed differences in HGF and TNF signaling pathways. Upper tract tumors tended to have high expression of genes associated with a luminal subtype. One of the genes most highly expressed in upper tract tumors, SLITRK6, is the target of an antibody drug conjugate (AGS15E) currently in phase I clinical trials.

Conclusions

This study provides evidence for molecular differences between upper tract and bladder urothelial carcinoma, some of which contribute to oncologic-relevant pathways. Upper tract tumors tended to express genes consistent with a luminal subtype. We also identify a marker, SLITRK6, as a potential target for patients with advanced upper tract urothelial carcinoma.     

Ureteroscopic management of upper urinary tract urothelial malignancies

The endoscope has made the transition from diagnostic tool to therapeutic aid in the upper urinary tract in recent years. Because of success using the ureteropyeloscope in the treatment of patients with upper tract stones and strictures, investigators are now looking at endoscopic management of urothelial malignancies above the bladder.     

Plenary Symposia

Studies of the urothelium, the specialized epithelial lining of the urinary bladder, are critical for understanding diseases affecting the lower urinary tract, including interstitial cystitis, urinary tract infections and cancer. However, our understanding of urothelial pathophysiology has been hampered by a lack of appropriate model systems. Here, we describe the isolation and characterization of a non-transformed urothelial cell line (TRT-HU1), originally explanted from normal tissue and immortalized with hTERT, the catalytic subunit of telomerase. We demonstrate responsiveness of the cells to anti-proliferative factor (APF), a glycopeptide implicated in the pathogenesis of interstitial cystitis. TRT-HU1 carries a deletion on the short arm of chromosome 9, an early genetic lesion in development of bladder cancer. TRT-HU1 urothelial cells displayed growth and migration characteristics similar to the low-grade papilloma cell line RT4. In contrast, we observed marked differences in both phenotype and gene expression profiles between TRT-HU1 and the highly malignant T24 cell line. Together, these findings provide the first demonstration of a non-transformed, continuous urothelial cell line that responds to APF. This cell line will be valuable for studies of both benign and malignant urothelial cell biology.     

Intracavitary Immunotherapy and Chemotherapy for Upper Urinary Tract Cancer: Current Evidence

A review of the literature was performed to summarize current evidence regarding the efficacy of topical immunotherapy and chemotherapy for upper urinary tract urothelial cell carcinoma (UUT-UCC) in terms of post-treatment recurrence rates. A Medline database literature search was performed in March 2012 using the terms upper urinary tract, urothelial cancer, bacillus Calmette-Guérin (BCG), and mitomycin C. A total of 22 full-text articles were assessed for eligibility, and 19 studies reporting the outcomes of patients who underwent immunotherapy or chemotherapy with curative or adjuvant intent for UUT-UCC were chosen for quantitative analysis. Overall, the role of immunotherapy and chemotherapy for UUT-UCC is not firmly established. The most established practice is the treatment of carcinoma in situ (CIS) with BCG, even if a significant advantage has not yet been proven. The use of BCG as adjuvant therapy after complete resection of papillary UUT-UCC has been studied less extensively, even if recurrence rates are not significantly different than after the treatment of CIS. Only a few reports describe the use of mitomycin C, making it difficult to obtain significant evidence.Key words: Upper urinary tract, Urothelial cell carcinoma, Bacillus Calmette-Guérin, Mitomycin C, Chemotherapy, ImmunotherapyAccording to the 2011 update of the European Guidelines for the diagnosis and management of upper urinary tract urothelial cell carcinoma (UUT-UCC),¹ urothelial carcinomas are the fourth most common tumors after prostate and breast cancer, lung cancer, and colorectal cancer. Bladder tumors account for 90% to 95% of urothelial carcinomas; UUT-UCC are relatively uncommon and account for only 5% to 10% of urothelial carcinomas. The annual incidence of UUT-UCC in Western countries is approximately one or two new cases per 100,000 inhabitants. Pyelocaliceal tumors are approximately twice as common as ureteral tumors. In 8% to 13% of cases, concurrent bladder cancer is present, and 60% of UUT-UCC are invasive at diagnosis, compared with only 15% of bladder tumors. This kind of carcinoma has a peak incidence in people in their 70s and 80s, with a higher prevalence in men.Radical nephroureterectomy (RNU) with excision of the bladder cuff represents the gold standard treatment for UUT-UCC, regardless of the location of the tumor in the upper urinary tract.¹ Lymph node dissection associated with RNU is of therapeutic interest and allows for optimal staging of the disease.Conservative surgery for low-risk UUT-UCC allows for preservation of the upper urinary renal unit; conservative management can be considered in imperative cases (renal insufficiency, solitary functional kidney) or in elective cases (ie, when the contralateral kidney is functional) for low-grade, low-stage tumors. Endoscopic ablation can be considered if a flexible ureteroscope, laser generator, and pliers (pluck) for biopsies are available, if the patient is informed of the need for closer follow-up, and if a complete resection is advocated.Segmental ureteral resection with wide margins provides adequate pathologic specimens for definitive staging and grade analysis while also preserving the ipsilateral kidney. Segmental resection is possible for the treatment of low- and high-risk tumors of the distal ureter, whereas segmental resection of the iliac and lumbar ureter is associated with a greater failure rate. Open resection of tumors of the renal pelvis or calices has almost disappeared.Percutaneous management can be considered for low-grade or noninvasive UUT-UCC that are inaccessible or difficult to manage by ureteroscopy, even if a theoretical risk of seeding exits in the puncture tract and if perforations occur during the procedure.After conservative treatment of UUT-UCC or for the treatment of carcinoma in situ (CIS), the instillation of bacillus Calmette-Guérin (BCG) or mitomycin C (MMC) is technically feasible by means of a percutaneous nephrostomy or even through a ureteric stent.Different agents have been used for topical therapy, including BCG, MMC, epirubicine, and thiotepa. Topical chemotherapeutic agents can be administered after endoscopic management, whereas instillations of BCG need to be postponed until the urothelium heals to avoid systemic side effects.According to a recent review,² topical therapy appears to be safe, although its efficacy is debatable. Complications from the administration of topical immunotherapy or chemotherapy can be avoided by maintaining low intracavitary pressures during administration. Renal function does not seem to be impaired after instillation of BCG or MMC.³ No systemic side effects result from perfusion with MMC, and persistent fever was reported in 5% of patients in combined major series after BCG administration; therefore, this side effect was resolved with appropriate antimicrobial therapy in all cases. Furthermore, up to 25% of patients may have granulomatous involvement of the urinary tract after BCG.This review summarizes current evidence about the efficacy of topical immunotherapy and chemotherapy in terms of post-treatment recurrence rates.     

Potential role of CCND1 G870A genotype as a predictor for urothelial carcinoma susceptibility and muscle-invasiveness in Taiwan

The cell cycle regulator cyclin D1 (CCND1) is thought to play a major role in the transition of cell cycle from G1 to S phase. It is known that a common CCND1 G870A genotype is associated with bladder cancer in Japan and China, but not in the Western World. There is neither a report about its role in Taiwan's population, nor its genetic role of CCND1 G870A in another worldwide urothelial cancer, upper tract urothelial cancer (UTUC). Therefore, we aimed at investigating the role of CCND1 G870A in both bladder cancer and UTUC in Taiwanese cohorts. The CCND1 G870A genotypes of 171 (101 bladder cancer and 70 UTUC) patients and 243 control subjects were determined by PCR-RFLP and their correlation with clinical and histopathological data was evaluated. The genotype analysis results showed that CCND1 GG genotype was associated with a lower risk overall in urothelial (P = 0.008, OR = 0.44, 95% CI = 0.24-0.81) and bladder cancer patients (P = 0.008, OR = 0.34, 95% CI = 0.15-0.76) than those of the AA genotype. In addition, patients carrying the AG genotype had a 0.29-fold lower odds ratio of muscle-invasive cancer procession (95% CI = 0.12-0.70) compared with those carrying the AA genotype in bladder cancer patients. Surprisingly, the GG genotype had a 5.88-fold higher odds ratio of muscle-invasive cancer procession (95% CI = 1.08-32.01) compared with those carrying the AA genotype in UTUC. No association between any CCND1 G870A genotype and higher-grade risk was found. Our results suggest that the G allele of the CCND1 G870A polymorphism may be a potential predictive and prognostic biomarker to distinguish between bladder cancer and UTUC in Taiwan.     

Endometrial Cancer as a Familial Tumor: Pathology and Molecular Carcinogenesis (Review)

Some cases of endometrial cancer are associated with a familial tumor and are referred to as hereditary nonpolyposis colorectal cancer (HNPCC or Lynch syndrome). Such tumors are thought to be induced by germline mutation of the DNA mismatch repair (MMR) gene, but many aspects of the pathology of familial endometrial cancer are unclear and no effective screening method has been established. However, the pathology of endometrial cancer with familial tumor has been progressively clarified in recent studies. At present, about 0.5% of all cases of endometrial cancers meet the clinical diagnostic criteria for HNPCC. A recent analysis of the three MMR genes (hMLH1, hMSH2 and hMSH6) revealed germline mutations in 18 of 120 cases (15.0%) of endometrial cancer with familial accumulation of cancer or double cancer, with a frameshift mutation of the hMSH6 gene being the most common. Many cases with mutation did not meet the current clinical diagnostic criteria for HNPCC, indicating that familial endometrial cancer is often not diagnosed as HNPCC. The results suggest that the hMSH6 gene mutation may be important in carcinogenesis in endometrial cancer and germline mutations of the MMR gene may be more prevalent in cases associated with familial accumulation of cancer. An international large-scale muticenter study is required to obtain further information about the pathology of endometrial cancer as a familial tumor.Key Words: HNPCC, Endometrial cancer, DNA mismatch repair gene, hMLH1, hMSH6.     

Missense mutations in hMLH1 associated with colorectal cancer

One of the most prevalent hereditary syndromes associated with colorectal cancer is hereditary nonpolyposis colorectal cancer (HNPCC). The inherited gene defects in HNPCC have been shown to reside in DNA mismatch repair genes, mostly hMSH2 or hMLH1. Most HNPCC patients are heterozygous with regard to the relevant mismatch repair gene; they have one normal and one mutated allele, and mismatch repair in normal somatic cells is functional. Cancer predisposition in HNPCC is believed to be associated with the loss of the wild-type allele in somatic cells, resulting in defective DNA mismatch repair. This gives rise to DNA microsatellite instability (MSI), an increased somatic mutation rate, and eventually, to the accumulation of mutations in genes involved in colorectal carcinogenesis. In support of this theory, colorectal tumors in HNPCC patients and in mice deficient for hMSH2 or hMLH1 show MSI. Here, we describe two missense mutations in hMLH1 exon 16 associated with colorectal cancer. Interestingly, the tumors do not show MSI. This raises some potentially important issues. First, even microsatellite-negative colorectal tumors can be associated with germline mutations and these will be missed if an MSI test is used to select patients for mutation screening. Second, the lack of MSI in these cases suggests that the mechanism involved in carcinogenesis could be different from that generally hypothesized.     

Hereditary Nonpolyposis Colon Cancer: Analysis of Linkage to 2p15-16 Places the COCA1 Locus Telomeric to D2S123 and Reveals Genetic Heterogeneity in Seven Canadian Families

Hereditary nonpolyposis colon cancer (HNPCC) is an autosomal dominant trait responsible for approximately 6% of colorectal cancers. Linkage of the HNPCC trait to the D2S123 locus on 2p15-16 has previously been reported in two families. This HNPCC locus is now designated “COCA1.” We have tested seven Canadian HNPCC families, who have a variety of clinical presentations, for linkage to a panel of microsatellite polymorphisms in the vicinity of D2S123. One family was clearly linked to the COCA1 locus (LOD = 4.21), and a second family is likely to be linked (LOD = 0.92). In three families linkage was excluded. In the remaining two families the data were inconclusive. In the linked family, individuals with cancer of the endometrium or ureter share a common haplotype with 12 family members with colorectal cancer. This supports the suspected association between these extracolonic neoplasms and the HNPCC syndrome. In addition, five of the six individuals with adenomatous polyps (but no colorectal cancer) have the same haplotype as the affected individuals, while the sixth carries a recombination. One individual with colorectal cancer carries a recombination that places the COCA1 locus telomeric to D2S123. This study localizes the COCA1 gene to an 8-cM region that is consistent with the location of the hMSH2 gene. We also confirm that families presently classified as HNPCC are genetically heterogeneous.     

Concurrent Preoperative Presence of Hydronephrosis and Flank Pain Independently Predicts Worse Outcome of Upper Tract Urothelial Carcinoma

Objectives

To investigate the impact of preoperative hydronephrosis and flank pain on prognosis of patients with upper tract urothelial carcinoma.

Methods

In total, 472 patients with upper tract urothelial carcinoma managed by radical nephroureterectomy were included from Kaohsiung Medical University Hospital Healthcare System. Clinicopathological data were collected retrospectively for analysis. The significance of hydronephrosis, especially when combined with flank pain, and other relevant factors on overall and cancer-specific survival were evaluated.

Results

Of the 472 patients, 292 (62%) had preoperative hydronephrosis and 121 (26%) presented with flank pain. Preoperative hydronephrosis was significantly associated with age, hematuria, flank pain, tumor location, and pathological tumor stage. Concurrent presence of hydronephrosis and flank pain was a significant predictor of non-organ-confined disease (multivariate-adjusted hazard ratio = 2.10, P = 0.025). Kaplan-Meier analysis showed significantly poorer overall and cancer-specific survival in patients with preoperative hydronephrosis (P = 0.005 and P = 0.026, respectively) and in patients with flank pain (P < 0.001 and P = 0.001, respectively) than those without. However, only simultaneous hydronephrosis and flank pain independently predicted adverse outcome (hazard ratio = 1.98, P = 0.016 for overall survival and hazard ratio = 1.87, P = 0.036 for and cancer-specific survival, respectively) in multivariate Cox proportional hazards models. In addition, concurrent presence of hydronephrosis and flank pain was also significantly predictive of worse survival in patient with high grade or muscle-invasive disease. Notably, there was no difference in survival between patients with hydronephrosis but devoid of flank pain and those without hydronephrosis.

Conclusion

Concurrent preoperative presence of hydronephrosis and flank pain predicted non-organ-confined status of upper tract urothelial carcinoma. When accompanied with flank pain, hydronephrosis represented an independent predictor for worse outcome in patients with upper tract urothelial carcinoma.     

Ultrasonography compared with intravenous urography in the investigation of adults with haematuria.

OBJECTIVE--To compare ultrasonography with intravenous urography in the investigation of adults with haematuria. DESIGN--Prospective study entailing the examination of all patients with both investigations concurrently. The investigations were performed independently on routine lists by different duty radiologists. Each was aware of the details of the request form but not of the findings of the other investigation. SETTING--Radiology department of a teaching hospital. PATIENTS--155 Consecutive adult patients (aged 18-93) referred from general practitioners and hospital outpatient clinics with a history of haematuria. FOLLOW UP--When results of both examinations proved normal no clinical or radiological follow up was sought. All abnormal findings of either investigation were correlated with results of subsequent imaging studies or operative findings. RESULTS--81 Patients (52%) had normal findings on urography and ultrasonography. Overall, the findings of ultrasonography concurred with those of urography in 144 cases (93%). Among the discrepant findings of the two investigations ultrasonography missed two ureteric calculi; one was in a non-dilated ureter, and in the other case ultrasonography detected the secondary ureteric dilatation. Ultrasound examination alone detected four bladder tumours not visible on urography with sizes ranging from 5 to 21 mm, representing one fifth of the 20 cystoscopically proved bladder tumours detected in the series. Ultrasonography detected all the 22 neoplastic lesions discovered in the study (20 bladder, two renal). Ultrasonography clarified the nature of renal masses evident in three urograms (simple cysts). CONCLUSIONS--Ultrasonography is a safe and accurate method of investigating the urinary tract in adults with haematuria. When combined with a single plain abdominal radiograph it proved to be superior to urography as the primary imaging study in this series. Ultrasonography should certainly be preferred to urography if cystoscopy is not planned. No urothelial tumours of the upper urinary tract were found in the series, reflecting their rarity. For those patients in whom ultrasonography and plain radiography have shown no abnormality and in whom cystoscopic appearances are normal urography would be advisable to exclude urothelial tumours of the upper urinary tract.     

Screening for an inherited susceptibility to colorectal cancer

The principal Mendelian disorders predisposing to colorectal cancer are familial adenomatous polyposis (FAP) and hereditary nonpolyposis colorectal cancer (HNPCC). FAP is caused by mutations in the adenomatous polyposis coli (APC) gene. HNPCC is caused by a mutation in one of at least five mismatch repair genes. It is important to identify individuals with these conditions because colon cancer will occur in at least 80% and onset is earlier than in the general population. Potential benefits of identification include improved compliance with recommended surveillance, early detection of polyps, reduction in cancer mortality, and reassurance for relatives found to be negative with attendant savings in the time and expense of surveillance. For classic FAP, the large number of polyps readily identifies affected persons. For HNPCC, identification of individuals meriting DNA sequencing requires either recognition of a suspect family history or finding high microsatellite instability in a tumor. Individuals accepting the offer of genetic counseling and DNA testing often have more cancers in their family, are motivated to inform relatives, have a larger social network, and have more confidence in their coping ability. Individuals who decline are often concerned about their own or their family's emotional reaction or fear discrimination.     

Soft tissue sarcoma and the hereditary non-polyposis colorectal cancer (HNPCC) syndrome: formulation of an hypothesis

Hereditary non-polyposis colorectal cancer (HNPCC) is a genetic disorder caused by mutation in one of the mismatch repair (MMR) genes (MLH1, MSH2, MSH6, PMS2) which predisposes to colorectal cancer and other malignances, that not yet include sarcomas. For sustaining that soft tissue sarcomas could be HNPCC related malignances, we report on a HNPCC patient with leiomyosarcoma and review the English literature. Overall, we report on eleven cases of soft tissue malignant tumors involving HNPCC patients, with a mean age of 34 years at diagnosis of sarcomas. In the majority of these tumors loss of MSH2 expression can be found at immunohistochemistry (IHC) and in 10 patients a germline mutation in one of the MMR genes was found (7 cases were MSH2 defective and 3 cases MLH1 defective). Data for supporting our hypothesis are also experimental, epidemiologic, histopathological: excess of sarcomas in PMS2 defective mice; sporadic soft tissue sarcomas are rare, with mean age at onset of 56 years and normal IHC for MMR proteins. In conclusion, the data collected support the hypothesis that soft tissue sarcomas could be included in the spectrum of tumors that, even if rarely, depend on MMR genes deficiency.     

Hereditary nonpolyposis colorectal cancer: causative role of a germline missense mutation in the hMLH1 gene confirmed by the independent occurrence of the same somatic mutation in tumour tissue

Evaluation of the causative role of germline mutations in DNA mismatch repair genes in hereditary nonpolyposis colorectal cancer (HNPCC) families can be difficult. Whereas nonsense, frameshift or splice-site mutations are presumed to lead to dysfunctional gene products and thus are generally considered to be causative, the evaluation of missense mutations often remains uncertain. We observed a novel germline mutation in the hMLH1 gene (His→Pro at codon 329) in an HNPCC family. The same missense mutation also occurred as a somatic event in the colonic tumours of two other HNPCC patients who had germline mutations at different sites of the hMLH1gene. Thus, the H329P mutation present in the germline can be considered as having an aetiological role in this HNPCC family. Received: 1 April 1997 / Accepted: 13 May 1997     

Tumorigenesis in colorectal tumors from patients with hereditary non-polyposis colorectal cancer

Tumorigenesis of colorectal cancer in patients with hereditary non-polyposis colorectal cancer (HNPCC) has been postulated to follow a different pathway from that of sporadic colorectal tumors. A characteristic of HNPCC-associated tumors is the replication error phenotype. We studied tumorigenesis in 8 fresh-frozen and 67 paraffin-embedded colorectal tumors derived from 29 families with HNPCC or a familial aggregation of colorectal cancer. By using intragenic markers, inactivation of the wild-type allele of hMLH1 was shown to occur through loss of heterozygosity and not through a somatic point mutation. Microsatellite instability is very common and occurs early in almost all colorectal tumors from HNPCC patients. Transforming growth factor β type II receptor (TβRII) mutations occur in these tumors at a high frequency. Of colorectal cancers from families with HNPCC, 63% have frameshift mutations in TβRII, compared with 10% of sporadic colorectal cancers. APC and K-RAS mutations appear to be as frequent in the HNPCC tumors as in the sporadic counterpart. Received: 3 March 1997 / Accepted: 23 June 1997     

Analysis of Tissue and Serum MicroRNA Expression in Patients with Upper Urinary Tract Urothelial Cancer

Introduction

MicroRNAs play an important role in many human malignancies; so far, their expression remains to be studied in upper urinary tract urothelial cancer (UUTUC).

Materials and Methods

The expression of eleven microRNAs (miR-10a, miR-21, miR-96, miR-135, miR-141, miR-182, miR-200b, miR-205, miR-429, miR-520b, miR-1244) formerly shown to be upregulated in urothelial bladder cancer were studied in corresponding normal and cancerous tissue samples of patients undergoing nephroureterectomy for UUTUC. Upregulated microRNAs were then measured in serum samples of patients with UUTUC and patients with non-malignant urological diseases to evaluate their potential as non-invasive biomarkers for UUTUC.

Results

MicroRNA expression allowed differentiation of normal and cancerous tissue: miR-21, miR-96, miR-135, miR-141, miR-182, miR-205, miR-429 and miR-520b were significantly overexpressed. Furthermore, miR-205 was upregulated in poorly differentiated UUTUC. The analysis of circulating RNA in serum demonstrated an increase of miR-141 in patients with UUTUC; receiver operator characteristic analysis demonstrated an area under the curve of 0.726 for miR-141 as a diagnostic biomarker. Furthermore, we observed lower levels of miR-10a and miR-135 in UUTUC patients.

Conclusions

MicroRNA expression is altered in UUTUC. The analysis of circulating miR-141 may be useful to identify patients with UUTUC.     

Role of alcoholism in the development of upper gastrointestinal tumors

A preliminary report on the results of studies on the relationship between alcohol abuse and upper gastrointestinal tumours is presented. Alcohol abuse was measured with the aid of a questionnaire. GGTP and mean MCV were determined. Within the 1st September, 1986--30th September, 1987, 75 patients with the cancer of the upper gastrointestinal tract and 107 patients with benign lesions to this area were examined. Alcohol abuse was found in 33% of patients with the cancer and 19% of patients with benign lesions to the upper gastrointestinal tract. This difference is statistically significant (p greater than 0.05). The results of GGTP and MCV values were statistically insignificant in both groups. The authors have found more marked correlation of alcohol abuse with the cancer of the upper gastrointestinal tract in relation to the oral cavity and pharynx than the stomach. Further studies including larger groups of patients are recommended.     

Purinergic signalling in the urinary tract in health and disease

Purinergic signalling is involved in a number of physiological and pathophysiological activities in the lower urinary tract. In the bladder of laboratory animals there is parasympathetic excitatory cotransmission with the purinergic and cholinergic components being approximately equal, acting via P2X1 and muscarinic receptors, respectively. Purinergic mechanosensory transduction occurs where ATP, released from urothelial cells during distension of bladder and ureter, acts on P2X3 and P2X2/3 receptors on suburothelial sensory nerves to initiate the voiding reflex, via low threshold fibres, and nociception, via high threshold fibres. In human bladder the purinergic component of parasympathetic cotransmission is less than 3 %, but in pathological conditions, such as interstitial cystitis, obstructed and neuropathic bladder, the purinergic component is increased to 40 %. Other pathological conditions of the bladder have been shown to involve purinoceptor-mediated activities, including multiple sclerosis, ischaemia, diabetes, cancer and bacterial infections. In the ureter, P2X7 receptors have been implicated in inflammation and fibrosis. Purinergic therapeutic strategies are being explored that hopefully will be developed and bring benefit and relief to many patients with urinary tract disorders.     

Collecting Duct Carcinomas Represent a Unique Tumor Entity Based on Genetic Alterations

Collecting duct carcinoma (CDC) is a rare renal neoplasm that is associated with poor prognosis due to its highly aggressive course and limited response to immuno- or chemotherapy. Histologically, CDC is defined as a subtype of renal cell carcinomas, but in some cases, it is difficult to differentiate from urothelial carcinomas (UC). Therefore the aim of this study was to determine genetic alterations of CDC in comparison to that of urothelial carcinomas of the upper urinary tract (UUT-UC) to clarify the histological origin of this rare tumor entity. Twenty-nine CDC samples were obtained from seven different German centers and compared with twenty-six urothelial carcinomas of the upper urinary tract. Comparative genomic hybridization (CGH) was used to investigate the genetic composition of patients’ tumors and allowed the detection of losses and gains of DNA copy numbers throughout the entire genome. The clinical data were correlated with CGH results. CGH analysis of CDC revealed DNA aberrations in many chromosomes. DNA losses were more frequently observed than gains, while high-level amplifications were not detected. The mean frequency of CDC chromosomal aberrations (4.9/case) was slightly lower than that in UUT-UC (5.4/case). Recurrent CDC DNA losses occurred at 8p (n=9/29), 16p (9/29), 1p (n=7/29) and 9p (n=7/29), and gains occurred in 13q (n=9/29). In contrast to CDC, the most frequently detected UUT-UC DNA aberration was a loss at 9q (n=13/26). DNA losses at 9q, 13q and 8q as well as gains at 8p showed significant variations in UUT-UC compared to CDC. There was no correlation between the patients’ clinical course and the presence or absence of these recurrent genetic alterations. CDCs are characterized by a different genetic pattern compared to UUT-UC. Regarding the published data on renal cell carcinoma, we conclude that CDC appears to be a unique entity among kidney carcinomas.     

A large MSH2 Alu insertion mutation causes HNPCC in a German kindred

Hereditary non-polyposis colorectal cancer (HNPCC) syndrome is an autosomal, dominantly inherited disease accounting for about 1%–5% of all colorectal cancer cases. HNPCC predisposition is caused by germline mutations in at least five genes coding for DNA mismatch repair (MMR) proteins. More than 400 MMR gene mutations have been identified in HNPCC patients. About 90% of mutations affect the MLH1 and MSH2 genes. The mutational spectrum mainly includes point mutations and small deletions or insertions. Here, we report a large 184 base-pair Alu insertion mutation in exon 6 of the MSH2 gene in a German HNPCC family. The inserted sequence contains repetitive Alu sequence elements that present the highest homology with the old Alu J subfamily. The Alu J insertion was most likely derived from Alu-mediated recombination, since Alu J elements have been found close to the insertion site in adjacent introns, and since elements pivotal for Alu retrotransposition are missing. Our results suggest that the recombination event occurred at least one generation ago. This is the first report of an Alu insertion in the coding sequence of a MMR gene as the cause of HNPCC. Our data thus further extend the spectrum of MMR gene mutations causative for HNPCC.M. Kloor and C. Sutter contributed equally to this work     

Two mismatch repair gene mutations found in a colon cancer patient – which one is pathogenic?

Hereditary nonpolyposis colorectal cancer (HNPCC) is a dominantly inherited cancer syndrome. Germline mutations in five different mismatch repair (MMR) genes, MSH2, MSH6, MLH1, MLH3, and PMS2 are linked to HNPCC. Here, we describe two colon cancer families in which the index patients carry missense mutations in both MSH2 and MSH6. The MSH2 mutation, I145M, is the same in both families, whereas the MSH6 mutations are different (R1095H and L1354Q). The families do not fulfil the international criteria for HNPCC, one family comprising two and the other family four colon cancer patients, all in one generation, resembling a recessive rather than dominant inheritance characteristic of HNPCC. The tumors of the index patients showed microsatellite instability. Functional analysis was performed to determine which one of the mutations could primarily underlie the cancer susceptibility in the families. MSH2 and MSH6 are known to form a heterodimeric complex (MutSalpha) responsible for mismatch recognition. The interaction of each mutated protein with its wild-type partner and with its mutated partner present in the colon cancer patient, and the MMR function of the mutated MutSalpha complexes were determined. Since none of the three mutations affected the MSH2-MSH6 interaction or the function of MutSalpha in an in-vitro MMR assay, our results suggest that alone the mutations do not cause MMR deficiency typical of HNPCC. However, our results do not exclude the possible compound pathogenicity of the two mutations.