No Evidence of Microsatellite Instability and Loss of Mismatch-Repair-Protein Expression in Squamous Cell Carcinoma of the Penis.

OBJECTIVE: Microsatellite instability (MSI) and a defective mismatch repair (MMR) system were described as beneficial tumor features for response to immune checkpoint therapy (PD-1 blockade). Meanwhile, the FDA approved PD-1/PD-L1 inhibition treatment for any solid tumor showing MSI and/or defects in the MMR system. For squamous cell carcinoma (SCC) of the penis, no data on the frequency of MSI and altered MMR protein expression are available to date. Therefore, we investigated the MSI status and the expression of MMR proteins in a large cohort of penile SCCs. METHODS: The MSI status of 105 archival formalin-fixed, paraffin-embedded penile SCCs was analyzed using the 5 markers of the NCI consensus panel for MIS testing (BAT25, 26, D2S123, D17S250, and D5S346), or, in cases without representative nontumorous tissue using a validated panel of 5 quasimonomorphic mononucleotide repeat markers (BAT 25, 26 and NR21, 24, 27). The expression of the MMR proteins MLH1, MSH2, MSH6, and PMS2 was analyzed using immunohistochemistry and a tissue microarray of a subset of penile SCCs from our cohort (n = 75). RESULTS: Overall, in 96/105 cases, at least 4 microsatellite markers gave interpretable results. None of the cases showed MSI. Immunohistochemistry for MMR proteins was analyzable in 70/75 cases. All cases showed a regular expression of the MMR proteins. CONCLUSION: MSI and defects in MMR protein expression are not regular features of penile SCC and might not act as biomarkers for PD-1/PD-L1 blockade therapy in penile carcinoma.

Paediatric and adult soft tissue sarcomas with NTRK1 gene fusions: a subset of spindle cell sarcomas unified by a prominent myopericytic/haemangiopericytic pattern.

Neoplasms with a myopericytomatous pattern represent a morphological spectrum of lesions encompassing myopericytoma of the skin and soft tissue, angioleiomyoma, myofibromatosis/infantile haemangiopericytoma and putative neoplasms reported as malignant myopericytoma. Lack of reproducible phenotypic and genetic features of malignant myopericytic neoplasms have prevented the establishment of myopericytic sarcoma as an acceptable diagnostic category. Following detection of a LMNA-NTRK1 gene fusion in an index case of paediatric haemangiopericytoma-like sarcoma by combined whole-genome and RNA sequencing, we identified three additional sarcomas harbouring NTRK1 gene fusions, termed 'spindle cell sarcoma, NOS with myo/haemangiopericytic growth pattern'. The patients were two children aged 11 months and 2 years and two adults aged 51 and 80 years. While the tumours of the adults were strikingly myopericytoma-like, but with clear-cut atypical features, the paediatric cases were more akin to infantile myofibromatosis/haemangiopericytoma. All cases contained numerous thick-walled dysplastic-like vessels with segmental or diffuse nodular myxohyaline myo-intimal proliferations of smooth muscle actin-positive cells, occasionally associated with thrombosis. Immunohistochemistry showed variable expression of smooth muscle actin and CD34, but other mesenchymal markers, including STAT6, were negative. This study showed a novel variant of myo/haemangiopericytic sarcoma with recurrent NTRK1 gene fusions. Given the recent introduction of a novel therapeutic approach targeting NTRK fusion-positive neoplasms, recognition of this rare but likely under-reported sarcoma variant is strongly encouraged.

No evidence for human papillomavirus infection in focal cortical dysplasia IIb.

OBJECTIVE: The etiology of focal cortical dysplasia type IIb (FCDIIb) remains enigmatic in patients suffering from drug-resistant epilepsy, and an aberrant activation of the mammalian target of rapamycin complex 1 signaling pathway (mTORC1) was detected in this developmental brain malformation. Recently, the human papillomavirus (HPV) oncoprotein E6 has been identified as a potent activator of mTORC1, and HPV16 E6 has been described to persist in balloon cells obtained from surgical FCDIIb specimens. Although this observation was replicated by an independent second report, it contradicts current knowledge of HPV biology. HPV infects the squamous or mucocutaneous epithelium; hematogenic spread into other tissues has not been observed. In addition, brain carcinogenesis has never been reported in FCDIIb patients. Herein, we have tried to confirm 2 previous reports of HPV16 E6 infection using an independent series of 14 surgical specimens with histopathologically confirmed FCDIIb. METHODS: Snap-frozen FCDIIb specimens were tested for HPV DNA using the primer set for amplification of the complete E6 reading frame of HPV16 and 3 other sets of primers (2 consensus primer sets detecting multiple HPV genotypes, and another primer set specifically used for HPV16). Furthermore, formalin-fixed and paraffin-embedded histopathological preparations were immunohistochemically analyzed using previously described antibodies directed against the HPV E6 oncoprotein. RESULTS: All 14 FCDIIb specimens were negative for HPV DNA with all 4 primer sets. Antibodies directed against the HPV E6 epitope showed weak labeling of cytoplasm in balloon cells, as previously described in FCDIIb, but also in other cell populations. INTERPRETATION: Our data did not confirm previously reported evidence for HPV16 detection in FCDIIb.

Frequency of TERT Promoter Mutations in Prostate Cancer.

OBJECTIVE: Recently, recurrent mutations within the core promoter of the human telomerase reverse transcriptase (TERT) gene generating consensus binding sites for ETS transcription factor family members were described in melanomas and other malignancies (e.g. bladder cancer, hepatocellular carcinoma). These mutations were discussed as early drivers for malignant transformation. In prostate cancer (PrCa) TERT expression has been associated with a poor prognosis and higher risk for disease recurrence. The underlying mechanisms for high TERT expression in PrCa have still not been clarified. To date, data on TERT promoter mutation analysis in PrCa are sparse. Therefore, we performed sequence analysis of the core promoter region of the TERT gene in an unselected cohort of prostate tumors. METHODS: Sections from 167 formalin-fixed, paraffin-embedded and cryopreserved prostate tumors were microdissected and used for DNA isolation. The mutation hotspot region within the TERT core promoter (-260 to +60) was analyzed by direct Sanger sequencing or SNaPshot analysis. RESULTS: All cases were analyzed successfully. Mutations within the core promoter of the TERT gene were not detected in any of the cases with all tumors exhibiting a wild-type sequence. CONCLUSION: TERT core promoter mutations reported from several other malignancies were not detected in our unselected cohort of PrCa. These data indicate that alterations within the core promoter of the TERT gene do not play an important role in prostate carcinogenesis.

Loss of MTUS1/ATIP expression is associated with adverse outcome in advanced bladder carcinomas: data from a retrospective study.

BACKGROUND: Seventy percent of all bladder tumours tend to recur and need intensive surveillance, and a subset of tumours progress to muscle-invasive and metastatic disease. However, it is still difficult to find the adequate treatment for every individual patient as it is a very heterogeneous disease and reliable biomarkers are still missing. In our study we searched for new target genes in the critical chromosomal region 8p and investigated the potential tumour suppressor gene candidate MTUS1/ATIP in bladder cancer. METHODS: MTUS1 was identified to be the most promising deleted target gene at 8p in aCGH analysis with 19 papillary bladder tumours. A correlation with bladder cancer was further validated using immunohistochemistry of 85 papillary and 236 advanced bladder tumours and in functional experiments. Kaplan-Meier analysis and multivariate Cox-regression addressed overall survival (OS) and disease-specific survival (DSS) as a function of MTUS1/ATIP expression. Bivariate correlations investigated associations between MTUS1/ATIP expression, patient characteristics and histopathology. MTUS1 expression was analysed in cell lines and overexpressed in RT112, where impact on viability, proliferation and migration was measured. RESULTS: MTUS1 protein expression was lost in almost 50% of all papillary and advanced bladder cancers. Survival, however, was only influenced in advanced carcinomas, where loss of MTUS1 was associated with adverse OS and DSS. In this cohort, there was also a significant correlation of MTUS1 expression and histological subtype: positive expression was detected in all micropapillary tumours and aberrant nuclear staining was detected in a subset of plasmocytoid urothelial carcinomas. MTUS1 was expressed in all investigated bladder cell lines and overexpression in RT112 led to significantly decreased viability. CONCLUSIONS: MTUS1 is a tumour suppressor gene in cultured bladder cancer cells and in advanced bladder tumours. It might represent one new target gene at chromosome 8p and can be used as an independent prognostic factor for advanced bladder cancer patients. The limitation of the study is the retrospective data analysis. Thus, findings should be validated with a prospective advanced bladder tumour cohort.

Lack of evidence for frequent MED12 p.L1224F mutation in prostate tumours from Caucasian patients.

Recently mutations in the MED12 gene have been reported in 5.4% of prostate tumours from Caucasian patients analysed by exome sequencing (Barbieri CE, Baca SC, Lawrence MS, et al. Exome sequencing identifies recurrent SPOP, FOXA1 and MED12 mutations in prostate cancer. Nature Genet 2012; 44: 685-689). In more than 70% of prostate tumours with MED12 mutation, a recurrent p.L1224F mutation in exon 26 was found. In order to validate this MED12 p.L1224F mutation, an unselected cohort of prostate tumours from Caucasian patients was analysed by Sanger sequencing. Overall, 223 prostate tumours and three lymph node metastases were analysed. The MED12 p.L1224F mutation could not be detected in any of the cases. So far, the recently reported MED12 p.L1224F mutation could not be validated in our unselected cohort of prostate tumours. Contrary to the findings of Barbieri et al, our data indicate either that the p.L1224F mutation in the MED12 gene plays no role in prostate carcinogenesis or that this alteration is only relevant in a small subgroup of tumours.

Clinical course of plasmacytoid urothelial carcinoma of the upper urinary tract: a case report.

Plasmacytoid urothelial carcinoma of the bladder represents a rare and aggressive variant of urothelial carcinoma, which is usually diagnosed at an advanced pathologic stage. Until now, no reports exist on this rare tumor type in the upper urinary tract. Herein, we present the first report on the clinical course of a metastatic plasmacytoid urothelial carcinoma of the renal pelvis and show its unfavorable outcome despite multimodal therapy.

Risk of penile tumor development in Caucasian individuals is independent of the coding variant rs7208422 in the TMC8 (EVER2) gene.

Genetic variation in the transmembrane channel-like (TMC)6/TMC8 region has been linked to ß-type human papillomavirus (HPV) infection and squamous cell carcinoma (SCC) of the skin and the head and neck, α-type HPV persistence and progression to cervical cancer. The functional variant rs7208422 of the TMC8 gene was suggested to have a high impact on susceptibility to ß-papillomaviruses and their oncogenic potential and to also have an influence on α-type HPV-related disease. The aim of the present study was to evaluate a possible influence of rs7208422 on penile cancer risk, a known α-type HPV-related malignancy. Therefore, the distribution of rs7208422 was determined by direct Sanger sequencing of 104 Caucasian penile SCC cases and compared to data of 3,810 controls taken from the literature. HPV detection was performed by usage of GP5+/6+ primers and subtype-specific PCR. It was observed that the distribution of rs7208422 followed the Hardy-Weinberg equilibrium in both cases and controls. HPV DNA was detected in 39% of the penile SCC cases. Overall, there was no significant difference in the distribution of rs7208422 neither between cases and controls (P=0.726) nor between HPV-positive and -negative penile SCC cases (P=0.747). There was also no association between rs7208422 genotypes and age of disease onset (P=0.740). In conclusion, the present data argue against a significant impact of rs7208422 on the risk for the development of penile SCC in Caucasians. Even in combination with the HPV status, the SNP appears not to influence the risk of penile SCC in HPV-positive cases.

TERT Promoter Mutation Analysis of Whole-Organ Mapping Bladder Cancers.

BACKGROUND: Multifocal occurrence is a main characteristic of urothelial bladder cancer (UBC). Whether urothelial transformation is caused by monoclonal events within the urothelium, or by polyclonal unrelated events resulting in several tumor clones is still under debate. TERT promoter mutations are the most common somatic alteration identified in UBC. In this study, we analyzed different histological tissues from whole-organ mapping bladder cancer specimens to reveal TERT mutational status, as well as to discern how tumors develop. METHODS: Up to 23 tissues from nine whole-organ mapping bladder tumor specimens, were tested for TERT promoter mutations including tumor associated normal urothelium, non-invasive urothelial lesions (hyperplasia, dysplasia, metaplasia), carcinoma in situ (CIS) and different areas of muscle invasive bladder cancers (MIBC). The mutational DNA hotspot region within the TERT promoter was analyzed by SNaPshot analysis including three hot spot regions (-57, -124 or -146). Telomere length was measured by the Relative Human Telomere Length Quantification qPCR Assay Kit. RESULTS: TERT promoter mutations were identified in tumor associated normal urothelium as well as non-invasive urothelial lesions, CIS and MIBC. Analysis of separate regions of the MIBC showed 100% concordance of TERT promoter mutations within a respective whole-organ bladder specimen. Polyclonal events were observed in five out of nine whole-organ mapping bladder cancers housing tumor associated normal urothelium, non-invasive urothelial lesions and CIS where different TERT promoter mutations were found compared to MIBC. The remaining four whole-organ mapping bladders were monoclonal for TERT mutations. No significant differences of telomere length were observed. CONCLUSIONS: Examining multiple whole-organ mapping bladders we conclude that TERT promoter mutations may be an early step in bladder cancer carcinogenesis as supported by TERT mutations detected in tumor associated normal urothelium as well as non-invasive urothelial lesions. Since mutated TERT promoter regions within non-invasive urothelial lesions are not sufficient alone for the establishment of cancerous growth, this points to the contribution of other gene mutations as a requirement for tumor development.

Exploring the MIR143-UPAR Axis for the Inhibition of Human Prostate Cancer Cells In Vitro and In Vivo.

MIR143 is pathologically downregulated and may function as a tumor suppressor in prostate cancer. Likewise, the urokinase plasminogen activator receptor (UPAR) is overexpressed in prostate carcinoma, representing a negative prognostic marker and putative therapeutic target gene. In this paper, we establish UPAR as a new direct target of MIR143. Luciferase reporter gene constructs identify one of the two in silico-predicted binding sites as functionally relevant for direct MIR143 binding to the 3' UTR, and, concomitantly, transfection of MIR143 reduces UPAR protein levels in prostate carcinoma cells in vitro. Inhibitory effects on cell proliferation and colony formation, spheroid growth and integrity, and cell viability are extensively analyzed, and they are compared to direct small interfering RNA (siRNA)-mediated uPAR knockdown or combined microRNA (miRNA)-siRNA treatment. Switching to a therapeutically more relevant in vivo model, we demonstrate tumor-inhibitory effects of MIR143 replacement therapy by systemic treatment of mice bearing subcutaneous PC-3 tumor xenografts with MIR143 formulated in polymeric nanoparticles. This efficient, nanoparticle-mediated delivery of intact MIR143 mediates the marked downregulation of uPAR protein, but not mRNA levels, thus indicating translational inhibition rather than mRNA degradation. In summary, we identify UPAR as a direct target gene of MIR143, and we establish the therapeutic anti-tumor potential of nanoparticle-based MIR143 replacement in prostate cancer.

P53 Codon 72 Polymorphism and Risk for Squamous Cell Carcinoma of the Penis: A Caucasian Case-Control Study.

Squamous cell carcinoma of the penis is a rare but often aggressive disease. A large proportion of penile cancers are associated with HPV infection, mainly with HPV high-risk subtypes 16 and 18. From other HPV-related malignancies a link between a functional SNP in the p53 gene (rs1042522, p.Arg72Pro) and a higher disease risk in the presence of HPV is documented. The p53 p.Arg72 variant was described as a risk factor for developing a malignancy in combination with the presence of HPV as the p.72Arg variant is more prone to HPV E6 protein-mediated degradation than the p.72Pro variant. For penile carcinoma there are only sparse data available on this topic. We therefore analyzed the distribution of this p53 codon 72 SNP in a cohort of 107 penile cancer patients and a healthy control group (n=194) using Restriction Fragment Length Polymorphism (RFLP) analysis. After DNA isolation a PCR amplicon including the variant nucleotide was generated. Based on the variant nucleotide this amplicon can be cleaved into two parts or remain unaffected by a restriction enzyme. Subsequent electrophoresis allowed the discrimination of SNP alleles in the investigated sample. Comparison of the allelic variants revealed no significant differences in the distribution of this SNP between cases and controls (p=0,622). There was also no difference in SNP distribution between cases with/without HPV infection (p=0,558) or histologic variants (p=0.339). In order to strengthen the impact of our data we performed a combined analysis of all published data on this topic with our results. This ended up in SNP distribution data from 177 cases and 1149 controls. Overall, there were also no significant differences in the allelic distribution of the p53 codon 72 SNP between either cases and controls (p=0,914) or HPV-positive and HPV-negative cases (p=0,486). From this most comprehensive data available to date we conclude that there is no influence of the p53 codon 72 SNP on the risk of development of penile carcinoma in Caucasians even in the presence of HPV.

Superficial acral fibromyxoma: clinicopathological, immunohistochemical, and molecular study of 11 cases highlighting frequent Rb1 loss/deletions.

Superficial acral fibromyxoma (SAF) is an uncommon benign dermal mesenchymal lesion of adults with predilection for acral sites, in particular the nail region. To date, less than 300 cases have been reported. SAFs consistently express CD34, but other diagnostic markers or specific genetic alterations have not been established yet. We describe 11 SAFs occurring in 7 men and 4 women aged 37 to 86years (median, 48 years). Mean size was 6mm (range, 4-20mm). Affected sites were fingers (n=5), toes (n=3), heel (n=1), calf (n=1), and unspecified digit (n=1). None of 10 patients with available follow-up (2-60months; median, 24months) developed recurrence. Histology showed relatively hypocellular vaguely lobulated nodules composed of bland-looking spindled or stellate fibroblast-like cells arranged into storiform or loose fascicles within a variably myxoid, fibromyxoid, or collagenous vascularized stroma. Immunohistochemistry showed expression of CD34 (9/10) and focal weak reactivity for epithelial membrane antigen (2/11). None of the lesions expressed protein S100 (0/11), MUC4 (0/11), or STAT6 (0/11). Loss of Rb1 immunoexpression was observed in 9 (90%) of 10 cases. All 7 cases with successful RB1 fluorescence in situ hybridization testing showed RB1 gene deletions, which was variably associated with co-loss of the corresponding 13q12 signal (monosomy at the 13q region). To our knowledge, this is the first study investigating the expression status of the tumor suppressor Rb1 in SAF by immunohistochemistry and fluorescence in situ hybridization. Our results showed frequent Rb1 deficiency as a possible driver molecular event in SAF (seen in 90% of cases) indicating relationship of SAF to the RB1-deleted tumor family.

Immunohistochemiocal subtyping using CK20 and CK5 can identify urothelial carcinomas of the upper urinary tract with a poor prognosis.

PURPOSE: Genome-wide analyses revealed basal and luminal subtypes of urothelial carcinomas of the bladder. It is unknown if this subtyping can also be applied to upper tract urothelial carcinomas. MATERIALS AND METHODS: Tumor samples from 222 patients with upper tract urothelial carcinomas who were treated with radical nephroureterectomy were analyzed for the expression of seven basal/luminal immunohistochemical markers (CK5, EGFR, CD44, CK20, p63, GATA3, FOXA1). RESULTS: Hierarchical clustering revealed a basal-like subtype (enrichment of CK5, EGFR and CD44) in 23.9% and a luminal-like subtype (enrichment of CK20, GATA3, p63 and FOXA1) in 13.1% of the patients. In 60.8%, little to no markers were expressed, whereas markers of both subtypes were expressed in 2.2%. By using CK5 and CK20 as surrogate markers for the basal and luminal subtypes, we defined four subtypes of upper tract urothelial carcinomas: (i) exclusively CK20 positive and CK5 negative (CK20+/CK5-), (ii) exclusively CK5 positive and CK20 negative (CK20-/ CK5+), (iii) both markers positive (CK20+/CK5+) and (iv) both markers negative (CK20-/CK5-). A receiver-operator analysis provided the optimal cut-off values for this discrimination. An immunoreactive score >1 for CK5 and >6 for CK20 were defined as positive. In multivariate Cox's regression analysis, the CK20+/CK5- subtype was an independent negative prognostic marker with a 3.83-fold increased risk of cancer-specific death (p = 0.02) compared to the other three subtypes. CONCLUSIONS: Immunohistochemical subgrouping of upper tract urothelial carcinomas by analyzing CK5 and CK20 expression can be performed in a routine setting and can identify tumors with a significantly worse cancer-specific survival prognosis.

Immunohistochemical and molecular characterizations in urothelial carcinoma of bladder in patients less than 45 years.

Bladder tumours in early-onset patients are rare and seem to exhibit unique clinicopathological features. Only few studies have investigated somatic alterations in this specific age of onset group and evidence is accumulating of a distinct molecular behaviour of early-onset bladder tumours. We collected the largest cohort of early-onset tumours of patients 45 years old or younger and aimed to test genomic alterations typically found in bladder cancer. Tumours of 118 early-onset patients were compared with a consecutive group of 113 cases. Immunohistochemistry of TP53, CK20 and Ki-67 was carried out. Molecular analysis was conducted to test for loss of heterozygosity of chromosome 9 and 17, as well as TP53 and FGFR3 mutations. Fisher´s exact and chi-squared test were appropriately used. No differences in grade/stage characteristics were observed. Overexpressed TP53 was differentially distributed between the two groups. TP53 nuclear accumulation was significantly more frequent in early-onset papillomas, PUNLMPs and pTa low-grade tumours compared to the consecutive cohort (p=0.005). Moreover, chromosome 9 deletions (29.5% vs. 44.6%) and FGFR3 mutations (34.5% vs. 63.7%) were less often detected in early-onset patients (p=0.05 and p<0.0001). By comparing the largest cohort of early-onset bladder cancer patients with an unselected group, we demonstrated that the typical molecular features are not independent of age at diagnosis. Our study supports the hypothesis of a distinct biological behaviour in early-onset tumours.

Hepatocyte differentiation markers in adenocarcinoma of the prostate: hepatocyte paraffin 1 but not arginase-1 is specifically expressed in a subset of prostatic adenocarcinoma.

Prostate adenocarcinoma and hepatocellular carcinoma (HCC) are common cancer types. Both may present with bone metastases, and both are known to be CK7/CK20 negative. Thus, diagnosis of less well-differentiated tumors at metastatic sites essentially relies on immunohistochemical confirmation. However, insufficient data exist on the expression status of the main 2 hepatocyte markers hepatocyte paraffin 1 (HepPar-1) and arginase-1 (Arg-1) in prostatic adenocarcinoma. We screened 557 prostate carcinoma cases for expression of these 2 markers using tissue microarrays. Sixty-four of 557 (11.5%) cases showed highly variable expression of HepPar-1 in 1% to 75% of tumor cells with a characteristically strong granular "mitochondrial" pattern. Only 13 cases (2.3%) expressed HepPar-1 in greater than 10% of the tumor cells. No correlation was seen with Gleason grade. On the other hand, 19 (3.4%) of 557 cases showed variable nonspecific cytoplasmic expression of Arg-1 distinct from the specific combined nucleocytoplasmic staining seen in normal liver and in HCC. Specifically, this Arg-1 pattern was seen only using one antibody lot and not another suggesting cross-reactivity. Only a single case showed specific nucleocytoplasmic expression of Arg-1 in the tumor cells. In conclusion, specific granular cytoplasmic staining for HepPar-1 is frequent in prostatic adenocarcinomas (11.5%) but usually focal and limited to less than 5% of tumor cells. This should not be misinterpreted as evidence of HCC, particularly in solid-pattern neoplasms. On the other hand, specific Arg-1 expression is very rare (0.18%), highlighting the value of Arg-1 in distinguishing HepPar-1-positive prostatic carcinoma from HCC at metastatic sites or in cases of liver metastasis from prostate carcinoma.

TERT Core Promotor Mutations in Early-Onset Bladder Cancer.

Activating mutations in the core promoter of the TERT gene have been described in many different tumor entities. In vitro models showed a two- to fourfold increase in transcriptional activity of the TERT promoter through creation of a consensus binding motif for Ets/TCF transcription factors caused by these mutations. TERT core promoter mutations are the most common mutations in bladder cancer with a frequency between 55.6% and 82.8% described so far, and are independent of stage and grade. Since limited data on molecular alterations of early-onset bladder tumors exists, we assessed the frequency of TERT core promoter mutations in early-onset bladder cancer. Two cohorts of bladder tumors (early-onset patient group; n=144 (age of onset of disease ≤45 years); unselected, consecutive group; n=125) were examined for TERT core promoter mutations. After microdissection and extraction of DNA the corresponding hotspot regions in the TERT core promoter were examined by Sanger-sequencing or a SNaPshot approach. A significantly lower frequency of TERT core promoter mutations was found in tumors from the early-onset cohort compared to the consecutive cohort (57.6% vs. 84.8%, p<0.001). Among the early-onset cohort cases younger than the cohort's median age of 39 years at disease onset showed a significantly reduced number of TERT promoter mutations (31/67, 46,3%) than cases aged between 39 and 45 years (52/77, 67.5%; p=0.012). This association was not found in the consecutive cases. Mutation status was independent of tumor stage and grade. We conclude that in tumors from early-onset bladder cancer patients TERT core promoter mutations are not as frequent as in bladder tumors from consecutive cases, but seem to play an important role there as well. In patients below 39 years of age TERT core promoter mutations are a more infrequent event, suggesting different mechanisms of tumorigenesis in these young patients.

Inactivating Mutations of RB1 and TP53 Correlate With Sarcomatous Histomorphology and Metastasis/Recurrence in Gastrointestinal Stromal Tumors.

OBJECTIVES: Loss-of-function mutations in TP53 and CDKN2A have been found at varying frequencies in gastrointestinal stromal tumors (GISTs), while no mutations of RB1 have been reported to date. The aim of the current study was to determine the mutation frequency of TP53, RB1, and CDKN2A in GISTs. METHODS: A cohort of 83 primary untreated GISTs was analyzed for mutations in TP53, RB1, and CDKN2A by massive parallel sequencing. Tumors with mutations in TP53 and RB1 were analyzed by fluorescence in situ hybridization for the corresponding gene loci. RESULTS: Two GISTs harbored inactivating mutations in RB1, and two other GISTs displayed inactivating mutations in TP53 All four tumors were KIT mutant high-risk tumors with highly cellular sarcomatous histomorphology and variable combinations of plump spindle cells to epithelioid highly atypical cells and high mitotic activity. Three of these patients developed recurrent or metastatic disease, while the fourth patient showed tumor rupture intraoperatively. The combined overall frequency of TP53 and RB1 mutations was 13% considering high-risk or malignant GISTs. CONCLUSIONS: TP53 and RB1 mutations seem to be restricted to high-risk/malignant GISTs and occur at an equal although relatively low frequency.

Functional analyses and prognostic significance of SFRP1 expression in bladder cancer.

PURPOSE: We previously showed that the Wnt-signaling antagonist SFRP1 (secreted frizzled-related protein 1) is a promising marker in bladder cancer. The aim of this study was to validate the prognostic role and analyze the functional significance of SFRP1. METHODS: Four bladder cancer cell lines (RT112, RT4, J82 and BFTC905) and one urothelial cell line (UROtsa) were used for functional characterization of SFRP1 expression. Effects on viability, proliferation and wound healing were investigated, and canonical Wnt-pathway activity as well as Wnt-signaling target gene expression was analyzed. Additionally, tissue micro-arrays from two different bladder tumor cohorts were evaluated for SFRP1 expression, and associations with survival and histopathological parameters were analyzed. RESULTS: The cell lines RT112, RT4, J82 and UROtsa showed SFRP1 expression. In BFTC905, SFRP1 expression was inhibited by promoter hypermethylation. Wnt-pathway activity was absent in all cell lines and independent from SFRP1 expression. RT112 and BFTC905 were used for further functional characterization. SFRP1 overexpression resulted in decreased viability and migration in BFTC905 cells. Knockdown of SFRP1 expression in RT112 cells resulted only in marginal effects. In bladder tumors, SFRP1 expression was associated with lower tumor grade, but not with progression in patients with papillary bladder cancer. SFRP1 expressing papillary bladder cancer tumors also demonstrated a tendency to longer overall survival. CONCLUSIONS: SFRP1 is reducing malignant potential of BFTC905 cells, but not by regulation of canonical Wnt-signaling pathway. Other pathways, like non-canonical Wnt or the MAPK pathway, could be activated via SFRP1-expression loss. In bladder tumors, SFRP1 has the potential to predict outcome for a subset of papillary bladder tumors.

Low frequency of HNPCC-associated microsatellite instability and aberrant MMR protein expression in early-onset bladder cancer.

OBJECTIVES: Recently, it was shown that patients with Lynch syndrome due to an MSH2 mutation are at increased risk for the development of bladder cancer. To further this discussion, we screened the largest investigated cohort of patients with early-onset bladder cancer for microsatellite instability (MSI) and mismatch repair (MMR) deficiency to determine a possible role of Lynch syndrome in young patients with bladder cancer. METHODS: A total of 109 cases of bladder tumors from young patients (aged <45 years) were examined for MSI (Bethesda consensus panel). Expression of MMR proteins (hMLH1, hMSH2, and hMSH6) was evaluated by immunohistochemistry using a tissue microarray. Results were compared with a series of unselected consecutive bladder tumors (n = 95). RESULTS: Regarding the frequency of MSI high (1% vs 0%) or abnormal expression of MMR proteins (2% vs 6.5%), no significant difference between the early-onset and unselected patient group was found. CONCLUSIONS: In young patients with bladder tumors, MSI and defects in MMR protein expression were not more frequent than in a series of consecutive bladder tumors. Most bladder tumors in young patients are not to be attributed to Lynch syndrome.

Frequency of activating mutations in FGFR2 exon 7 in bladder tumors from patients with early-onset and regular-onset disease.

The FGF/FGFR-system plays an important role in embryogenesis, tissue homeostasis and carcinogenesis. Mutational activation of FGFR2 resulting in aberrant FGFR2 signaling activation is known from both hereditary germ line alterations and somatic mutations in various malignancies (e.g. breast, gastric or ovarian cancer). FGFR2 mutations are mainly located within the hinge between Ig-like domains (exon 7), around the 3rd Ig-like domains and within the kinase domain. For bladder cancer only sparse data on FGFR2 mutations are available. Most interestingly a case of early-onset papillary carcinoma of the bladder showing a FGFR2 p.Pro253Arg mutation in exon 7 in a patient with Apert Syndrome was reported recently. To further evaluate the importance of FGFR2 exon 7 alterations in bladder cancer a cohort of 254 bladder tumors (cohort 1: unselected cases: n=139; cohort 2: early-onset bladder cancer cases (age at time of diagnosis≤45 years): n=115) was analyzed. Sections from formalin-fixed, paraffin-embedded bladder tumors were used for DNA isolation. After precise microdissection exon 7 of the FGFR2 gene was analyzed by direct Sanger sequencing. All cases could be analyzed successfully. Mutations in exon 7 of FGFR2 could not be detected in any of the cases. All tumors showed wild type sequence. Our data demonstrate that the recently reported association between early-onset papillary carcinoma of the bladder with germ line FGFR2 p.Pro253Arg mutation could not be found in our cohorts of sporadic bladder tumors. These results indicate that FGFR2 gene mutations might only play a minor role in bladder carcinogenesis.