PIK3CA mutations are an early genetic alteration associated with FGFR3 mutations in superficial papillary bladder tumors

Bladder tumors constitute a very heterogeneous disease. Superficial tumors are characterized by a high prevalence of FGFR3 mutations and chromosome 9 alterations. High-grade and muscle-invasive tumors are characterized by Tp53 mutations and aneuploidy. We have analyzed the sequence of exons 9 and 20 of PIK3CA in a panel of bladder tumors covering the whole spectrum of the disease. DNA from formalin-fixed, paraffin-embedded tumor sections was amplified by PCR and products were sequenced. In an unselected panel of tumors representative of the disease, the PIK3CA mutation prevalence was 13% (11 of 87). Mutations occurred mainly at the previously identified hotspots (codons 542, 545, 1007, and 1047). The distribution according to stage was as follows: papillary urothelial neoplasms of uncertain malignant potential (PUNLMP; 11 of 43, 25.6%), T(a) (9 of 57, 16%), T(1) (2 of 10, 20%), and muscle-invasive tumors (0 of 20, 0%; P = 0.019). Mutations were associated with low-grade tumors: grade 1 (6 of 27, 22.2%), grade 2 (3 of 23, 13%), and grade 3 (2 of 37, 5.4%; P = 0.047). Overall, PIK3CA mutations were strongly associated with FGFR3 mutations: 18 of 69 (26%) FGFR3(mut) tumors were PIK3CA(mut), versus 4 of 58 (6.9%) FGFR3(wt) tumors (P = 0.005). Our findings indicate that PIK3CA mutations are a common event that can occur early in bladder carcinogenesis and support the notion that papillary and muscle-invasive tumors arise through different molecular pathways. PIK3CA may constitute a novel diagnostic and prognostic tool, as well as a therapeutic target, in bladder cancer.     

FGFR3 and P53 characterize alternative genetic pathways in the pathogenesis of urothelial cell carcinoma

Fibroblast growth factor receptor 3 (FGFR3) and P53 mutations are frequently observed in bladder cancer. We here describe the distribution of FGFR3 mutations and P53 overexpression in 260 primary urothelial cell carcinomas. FGFR3 mutations were observed in 59% and P53 overexpression in 25%. Interestingly, FGFR3 and P53 alterations were mutually exclusive, because they coincided in only 5.7% of tumors. Consequently, we propose that they characterize two alternative genetic pathways in urothelial cell carcinoma pathogenesis. The genetic alterations were reflected in the pathology and the clinical outcome, i.e., FGFR3 mutations were found in low-stage/-grade tumors and were associated with a favorable disease course, whereas P53 alterations were tied to adverse disease parameters.     

Mutations in TP53, but not FGFR3, in urothelial cell carcinoma of the bladder are influenced by smoking: contribution of exogenous versus endogenous carcinogens

Smoking is a major risk factor for urothelial cell carcinoma of the bladder (UCC). Mutations in the FGFR3 and TP53 genes have been shown to define two distinct pathways in superficial papillary and invasive UCC disease, respectively. We investigated the relationship between smoking and these mutations by means of denaturing high performance liquid chromatography and sequencing for 110 primary UCC of the bladder. This study included 48 current smokers, 31 ex-smokers and 31 non-smokers. Thirty-five of the tumors were stage pTa, 40 pT1 and 35 > or =pT2. Fourteen of the tumors were grade 1, 37 were grade 2 and 59 grade 3. Smoking was associated with high stage (P = 0.03) and high grade tumors (P = 0.006). Twenty-two of the 110 tumors studied harbored TP53 mutations (20%) and 43 harbored FGFR3 mutations (39%). Odds ratios (OR) were higher for TP53 mutations in current smokers [OR, 2.25; 95% confidence interval (95% CI), 0.65-7.75] and ex-smokers (OR, 1.62; 95% CI, 0.41-6.42) than in non-smokers. Double TP53 mutations and the A:T-->G:C TP53 mutation pattern was found only in current smokers. Patients with the FGFR3(wild-type)/TP53(mutated) genotype had significantly higher levels of tobacco consumption, as measured in pack-years (P = 0.01). Smoking influenced neither the frequency nor the pattern of FGFR3 mutations. Our results suggest that smoking is associated with invasive and high grade UCCs, at initial presentation, and influenced TP53 or the molecular pathway defined by these mutations. In contrast, FGFR3 mutations are not affected by smoking and probably result from endogenous alterations. These data have potential implications for clinical management and prevention strategies.     

Role of activating fibroblast growth factor receptor 3 mutations in the development of bladder tumors.

PURPOSE: Bladder tumors develop through different molecular pathways. Recent reports suggest activating mutations of the fibroblast growth factor receptor 3 (FGFR3) gene as marker for the "papillary" pathway with good prognosis, in contrast to the more malignant "carcinoma in situ" (CIS) pathway. The aim of this clinical follow-up study was to investigate the role of FGFR3 mutations in bladder cancer development in a longitudinal study. EXPERIMENTAL DESIGN: We selected 85 patients with superficial bladder tumors, stratified into early (stage T(a)/grade 1-2, n = 35) and more advanced (either stage T(1) or grade 3, n = 50) developmental stages. The patients were followed prospectively, and metachronous tumors were included. We did screening for FGFR3 and TP53 mutations by direct bidirectional sequencing and for genome-wide molecular changes with microarray technology. RESULTS: A total of 43 of 85 cases (51%) showed activating mutations of FGFR3. The mutations were associated with papillary tumors of early developmental stage. However, after stratifying for developmental stage, FGFR3-mutated tumors showed the same malignant potential as wild-type tumors. Tumors with concomitant CIS were generally FGFR3 wild type. They were characterized by different patterns of chromosomal changes and gene expression signatures compared with FGFR3-mutated tumors, indicating different molecular pathways. CONCLUSIONS: FGFR3 mutations seem to have a central role in the early development of papillary bladder tumors. These tumors follow a common molecular pathway, which is different from tumors with concomitant CIS. FGFR3 mutations do not seem to play a role in bladder cancer progression.     

Fibroblast growth factor receptor 3 protein expression in urothelial carcinoma of the urinary bladder, exhibiting no association with low-grade and/or non-invasive lesions

Activating mutations of fibroblast growth factor receptor 3 (FGFR3), found in autosomal dominant human skeletal dysplasia, were reported to be involved in tumorigenesis and correlate with low-grade and superficial lesions of urothelial carcinoma. FGFR3 protein expression was immunohistochemically investigated in 126 cases of urothelial carcinoma of the urinary bladder to evaluate the role of this receptor in tumor behavior. p53 expression and the proliferating activity of tumor cells, assessed by Ki-67 expression, were also analyzed in parallel. Cytoplasmic and/or membrane immunostaining for FGFR3 was observed in 62 (49.2%) cases, including 20 (15.9%) cases of intense staining and 42 (33.3%) of moderate staining. p53 expression and Ki-67 labeling index (LI) were significantly correlated with high tumor grade (p=0.0093 and <0.0001, respectively) and invasion (p=0.0041 and <0.0001, respectively). Although there were two groups of interesting cases: low-grade and non-invasive tumors negative for p53 but positive for FGFR3, and high-grade and invasive tumors positive for p53 but negative for FGFR3, no statistically significant relationship was found between FGFR3 expression and tumor grade, invasion, p53 expression or Ki-67 LI. These results suggest that FGFR3 protein expression in bladder cancer is unlikely to affect tumor behavior as a unique single factor.     

Fibroblast growth factor receptor 3 mutation in voided urine is a useful diagnostic marker and significant indicator of tumor recurrence in non-muscle invasive bladder cancer

The fibroblast growth factor receptor (FGFR)-3 gene encodes a receptor tyrosine kinase that is frequently mutated in non-muscle invasive bladder cancer (NMIBC). A sensitive and quantitative assay using peptide nucleic acid-mediated real-time PCR was developed for detecting FGFR 3 mutations in the urine samples and evaluated as a molecular marker for detecting intravesical recurrence of NMIBC in patients undergoing transurethral resection of bladder tumor. FGFR 3 mutation was examined in tumor tissues and serially taken pre- and postoperative urine sediments in 45 NMIBC patients with a median follow up of 32 months. FGFR 3 mutations were detected in 53.3% (24/45) of primary tumor tissues, among which intravesical recurrence developed in 37.5% (9/24) of cases. FGFR 3 mutation in the primary tumor was not a significant prognostic indicator for recurrence, while the proportion of FGFR 3 mutation (i.e. tumor cellularity was ≥11%) in the preoperative urine sediments was a significant indicator for recurrence in patients with FGFR 3 mutations in the primary tumors. FGFR 3 mutations were detected in 78% (7/9) of postoperative urine samples from recurrent cases with FGFR 3 mutations in the tumor, while no mutations were detected in the urine of 15 non-recurrent cases. Urine cytology was negative in all cases with FGFR 3 mutations in the primary tumors, while the sensitivity of cytological examination was as high as 56% (5/9) in cases showing wild-type FGFR 3 in the primary tumors. Urine FGFR 3 mutation assay and cytological examination may be available in the future as complementary diagnostic modalities in postoperative management of NMIBC. ( Cancer Sci 2009)     

Progression in transitional cell carcinoma of the urinary bladder--analysis of Tp53 gene mutations by temperature gradients and sequence in tumor tissues and in cellular urine sediments

The relationship between expression of p53 protein in bladder cancer and tumor progression is known. In this paper, we attempt to study this phenomenon by molecular-genetic techniques. One hundred thirty-seven bladder tumor tissues were obtained from transurethral resection (TURB). Urine sediments were collected from 72 patients suffering from transitional cell carcinoma and tumor recurrence. These patients were followed up for at least three months. Separate polymerase chain reactions (PCR) were carried out for exons 5, 6, 7, and 8 of the Tp53 gene. Temperature gradient gel electrophoresis (TGGE) was used to screen mutations in the PCR products. Sequencing from reamplified mutant and wildtype bands was excised from the TGGE. Tp53 mutation frequency is 43.1% in 137 bladder cancer specimens, but already 32.7% of Ta-tumors (16/49) were Tp53 mutated. Four of 25 patients with Tp53 wild-type tumors suffered from progression. In the group of patients with Tp53 mutated cancer, seven of 12 had a tumor progression. In 11 of 14 patients with Tp53 mutation in cancer tissue, the same mutation was also found in urine sediments. In such patients, successful tumor treatment by TURB results in loss of their Tp53 mutation in urine sediment, and tumor recurrency resulted in reappearance.     

Identification of fibroblast growth factor receptor 3 mutations in urine sediment DNA samples complements cytology in bladder tumor detection

BACKGROUND: Mutations in fibroblast growth factor 3 receptor (FGFR3) are frequent events in low-grade bladder tumors. To assess the potential utility of the detection of FGFR3 mutations in a screening modality, the authors analyzed urine sediment DNA samples from 192 patients in a retrospective study. METHODS: Urine sediment DNA samples from 192 patients were prepared. Seventy-two patients had undergone transurethral resection (TURBT group) of mainly Ta lesions and 120 patients had undergone cystectomy (cystectomy group). The majority of patients in the cystectomy group had more advanced tumors compared with patients in the TURBT group. DNA preparations were screened for FGFR3 mutations in exons 7, 10, and 15 using single-strand conformation polymorphism (SSCP) and DNA sequencing. RESULTS: Using SSCP, 67% of patients in the TURBT group and 28% in the cystectomy group displayed FGFR3 mutations. Comparative analysis of cytology results and FGFR3 mutational analysis were performed in 122 cases. Within the TURBT group, FGFR3 mutation analysis outperformed cytology. FGFR3 mutation analysis identified change in 68% of urine sediment DNA samples whereas cytology recorded the presence of tumor cells in 32% of the DNA samples. In the cystectomy group, cytology outperformed FGFR3 mutation analysis. Cytology recorded tumor detection in 90% of patients, while SSCP identified mutational change in 24%. CONCLUSIONS: Combining FGFR3 mutation results with cytology in both groups correctly identified tumor presence in 105 of 122 (86%) of patients. The greater sensitivity of FGFR3 mutation detection over cytology in identifying the presence of low-grade, superficial bladder tumors represents a potential new tool to complement standard cytology in screening patients for bladder tumors and recurrent disease.     

Molecular characterization of early-stage bladder carcinomas by expression profiles, FGFR3 mutation status, and loss of 9q

We used gene expression profiling, mutation analyses of FGFR3 and TP53, and LOH analyses of chromosome 9 and the TP53 region on chromosome arm 17p, to molecularly characterize 75 Ta and T1 bladder carcinomas. We identified four major cellular processes related to cell cycle, protein synthesis, immune response, and extra cellular components that contribute to the expressional heterogeneity of early-stage urothelial cell carcinoma (UCC). Activating FGFR3 mutations were found at the highest frequency in G1 tumors (80%), and showed a strong correlation with FGFR3 expression. In contrast, G3 tumors displayed mutations in less than 10% of the cases and a low level of FGFR3 expression. Even though LOH on chromosome 9 was not associated with any specific expression pattern, our data indicate that loss of chromosome 9 is associated with tumor development rather than initiation. The combined analyses suggest the existence of two types of UCC tumors, one which is characterized by FGFR3 mutation or expression, high expression of protein synthesis genes, and low expression of cell cycle genes. Furthermore, the presented data underscore FGFR3 receptor involvement in urothelial cell transformation as the presence of FGFR3 mutations has a major impact on the global gene expression profile of bladder carcinomas.     

LOH and mutational analysis of p53 alleles in mouse urinary bladder carcinomas induced by N-butyl-N-(4-hydroxybutyl) nitrosamine

In human urinary bladder carcinogenesis, alterations in the p53 tumor suppressor gene are common events. We have previously reported that they are also frequent in invasive urinary bladder carcinomas induced by N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) in NON/Shi mice. To further investigate the significance of the p53 gene status for mouse urinary bladder carcinogenesis, we examined both allele loss and mutational alterations in urinary bladder cancers of (NON/Shi x C3H/He/Shi) F1 hybrid mice exposed to the carcinogen for 12 weeks and then maintained for a further 9 weeks without treatment. An intragenic silent polymorphism within exon 7 of the p53 gene between NON/Shi and C3H/He/Shi mice allows assessment of allele loss of the p53 gene and determination of the parental origin of mutated and/or lost alleles. A tissue microdissection method was employed to obtain carcinoma samples without excessive contamination with normal tissue. Allele losses were detected in one of 14 tumors (7.1%) and nine mutations in eight of 14 (57%) tumors were found in exons 5-8 by polymerase chain reaction-single strand conformation polymorphism followed by DNA direct sequencing analysis. All mutations involved one base substitution with an amino acid change, although the types of base substitution were random. In conclusion, the high incidence of p53 alterations suggests a significant role in the genesis of invasive urinary bladder tumors in BBN-treated mice.     

Combined microsatellite and FGFR3 mutation analysis enables a highly sensitive detection of urothelial cell carcinoma in voided urine.

PURPOSE: Fibroblast growth factor receptor 3 (FGFR3) mutations were reported recently at a high frequency in low-grade urothelial cell carcinoma (UCC). We investigated the feasibility of combining microsatellite analysis (MA) and the FGFR3 status for the detection of UCC in voided urine. EXPERIMENTAL DESIGN: In a prospective setting, 59 UCC tissues and matched urine samples were obtained, and subjected to MA (23 markers) and FGFR3 mutation analysis (exons 7, 10, and 15). In each case, a clinical record with tumor and urine features was provided. Fifteen patients with a negative cystoscopy during follow-up served as controls. RESULTS: A mutation in the FGFR3 gene was found in 26 (44%) UCCs of which 22 concerned solitary pTaG1/2 lesions. These mutations were absent in the 15 G3 tumors. For the 6 cases with leukocyturia, 46 microsatellite alterations were found in the tumor. Only 1 of these was also detected in the urine. This was 125 of 357 for the 53 cases without leukocyte contamination. The sensitivity of MA on voided urine was lower for FGFR3-positive UCC (15 of 21; 71%) as compared with FGFR3 wild-type UCC (29 of 32; 91%). By including the FGFR3 mutation, the sensitivity of molecular cytology increased to 89% and was superior to the sensitivity of morphological cytology (25%) for every clinical subdivision. The specificity was 14 of 15 (93%) for the two (molecular and morphological) cytological approaches. CONCLUSIONS: Molecular urine cytology by MA and FGFR3 mutation analysis enables a highly sensitive and specific detection of UCC. The similarity of molecular profiles in tumor and urine corroborate their clonal relation.     

FGFR3和PIK3CA基因突变影响膀胱癌的预后

背景与目的：成纤维细胞生长因子受体3（fibroblast growth factor receptor 3,FGFR3）和磷脂酰肌醇3-激酶催化亚基ɑ（phosphoinositide 3 kinase catalytic alpha polypeptide,PIK3CA）基因突变与多种肿瘤的发生、发展密切相关。然而,其临床病理意义尚未明确。探讨FGFR3和PIK3CA基因突变对膀胱癌预后的影响。方法：采用Sanger基因测序技术分析于南京中医药大学张家港附属医院行手术治疗的63例膀胱癌患者中FGFR3（外显子7、10、15）和PIK3CA（外显子9、20）基因突变,同时采用免疫组织化学方法检测FGFR3和PIK3CA蛋白水平。分析FGFR3和PIK3CA基因突变与各临床参数的关系,应用Kaplan-Meier方法进行生存分析,通过多因素COX模型回归分析方法对影响膀胱癌预后的因素进行分析。结果：FGFR3基因突变率为17.46%（11/63）,蛋白表达率为33.33%（21/63）,PIK3CA基因突变率为7.93%（5/63）,蛋白表达率为55.56%（35/63）。FGFR3基因突变与年龄、肿瘤是否复发显著相关（P<0.05）,PIK3CA基因突变与各临床参数均无显著相关性（P>0.05）;11例FGFR3 ^mut 中2例PIK3CA ^mut ,52例FGFR3 ^wt 中3例PIK3CA ^mut ,两者比较,差异有统计学意义（χ ² =4.61,P=0.03）。FGFR3基因突变型和野生型的无进展生存期（progression-free survival,PFS）分别为29.13和46.25个月,差异有统计学意义（P=0.021）,而两组的总生存期（overall survival,OS）差异无统计学意义（P>0.05）;PIK3CA基因突变型和野生型比较OS和PFS,差异均无统计学意义（P>0.05）。多参数COX回归分析影响膀胱癌的因素中,FGFR3和PIK3CA基因突变和蛋白表达均不是影响OS的主要因素,病理学分级是影响OS的主要因素,吸烟史和FGFR3基因突变则是影响PFS的主要因素。结论：FGFR3基因突变是膀胱癌预后的不利因素,PIK3CA更易在FGFR3突变的膀胱癌中突变,可能促进FGFR3突变型膀胱癌的恶性行为。     

Multiple detection of genetic alterations in tumors and stool.

Detection of genetic alterations in exfoliated intestinal cells in stool could represent an alternative, noninvasive tool for the screening of colorectal tumors. To verify this, we analyzed p53 and K-ras mutations and microsatellite instability on 46 cases of colorectal cancer and compared the presence of molecular alterations in tumor tissue and stool samples from individual patients. p53 exons 5-8 and K-ras exons 1-2 were analyzed by denaturing gradient gel electrophoresis. For the microsatellite instability, a set of 5 microsatellite markers (D2S123, D5S346, D17S250, BAT25, and BAT26) was evaluated. In the 18 healthy individuals, no genetic alterations in either tissue or stool were detected. p53 mutations were detected in 17 (37%), K-ras alterations in 15 (33%), and microsatellite instabilities in 5 (11%) of the 46 tumors analyzed. In a side study, we analyzed the correlation in genetic alteration profiles between tumors and macroscopically normal or healthy tissue from the same patient. The presence of at least one molecular alteration in tumor was observed in 31 (67%) of the cases. p53, K-ras mutations, and microsatellite instabilities were detected in stool samples in 18, 40, and 60% of patients with tumors harboring the same alterations. Due to the largely complementary presence of p53 and K-ras mutations in tumors, the use of highly sensitive procedures for stool analysis could offer a means competitive with colonoscopy and the fecal occult blood test.     

The fibroblast growth factor receptor 3 (FGFR3) mutation is a strong indicator of superficial bladder cancer with low recurrence rate

We analyzed the possible prognostic value of the recently discovered fibroblast growth factor receptor 3 (FGFR3) mutations in bladder cancer. A FGFR3 mutation was found in 34 of 53 pTaG1-2 bladder cancers, whereas none of the 19 higher-staged tumors had a mutation (P < 0.0001). In 57 patients with superficial disease followed prospectively by cystoscopy for 12 months, 14 of 23 patients in the wild-type FGFR3 group developed recurrent bladder cancer compared with only 7 of 34 patients in the mutant group (P = 0.004). The recurrence rate per year was 0.24 for the FGFR3 mutant tumors and 1.12 for tumors with a wild-type FGFR3 gene. In addition, FGFR3 mutation status was the strongest predictor of recurrence when compared with stage and grade (P = 0.008). This is the first mutation in bladder cancer that selectively identifies patients with favorable disease characteristics. Our results suggest that the frequency of cystoscopic examinations can be reduced considerably in patients with FGFR3-positive tumors.     

Somatic mutations of fibroblast growth factor receptor 3 (FGFR3) are uncommon in carcinomas of the uterine cervix

Germline mutations of the gene encoding human fibroblast growth factor receptor 3 (FGFR3) have been shown to be responsible for several related autosomal dominant forms of syndromic craniosynostosis and short limb dwarfism. Somatic activating mutations of FGFR3 were recently reported to occur in three of 12 (25%) uterine cervical carcinomas and nine of 26 (35%) bladder carcinomas, suggesting that constitutive activation of FGFR3 may be an important mechanism underlying the development and/or progression of these common epithelial malignancies. In order to investigate further a possible role for FGFR3 mutations in cervical carcinogenesis, we performed sequence-based mutational analysis of FGFR3 in 51 primary cervical carcinomas and seven cervical carcinoma-derived cell lines. The regions analysed (exons 7, 10, 13, 15, and 19) encompassed all previously described FGFR3 mutations. A single nucleotide substitution at codon 249, predicting a serine to cysteine amino acid substitution (S249C) in the FGFR3 extracellular domain, was identified in one primary tumor. Only wild type FGFR3 alleles were identified in the remaining tumors and cell lines. The S249C mutation is the only FGFR3 mutation described to date in cervical carcinomas. These findings suggest that while activating mutations of FGFR3 occur in cervical cancer, they may not be as common as initially reported.     

Fibroblast Growth Factor Receptor 3 Mutations in Bladder Tumors Correlate with Low Frequency of Chromosome Alterations

The aim of this study was to analyze the distribution of FGFR3 mutations in bladder tumors of different grade and stage and determine the relation of mutations to chromosomal alterations detected by comparative genomic hybridization (CGH). One hundred bladder cancer samples served as templates for manual microdissection. DNA was isolated from dissected samples containing at least 80% tumor cells. Mutations in FGFR3 were analyzed by SNaPshot analysis. CGH was carried out according to standard protocols. FGFR3 mutations were detected in 45 of 92 samples (48.9%). Concerning T-category, the following mutation frequencies occurred: pTa, 69%; pT1, 38%; and pT2-3, 0%. The mutation frequency was significantly associated with tumor grade: G1, 72%; G2, 56%; and G3, 4%. In pTaG1 tumors, mutations were found in 74%. A significantly lower number of genetic alterations per tumor detected by CGH was associated with FGFR3 mutations (2 vs 8). This association was also seen in pTaG1 tumors: 2.5 (with mutation) vs 7.5 (without mutation). FGFR3 mutations characterize noninvasive low-risk tumors of low malignancy. The low malignant potential of these tumors is underlined by a low number of genetic alterations per tumor. Therefore, FGFR3 represents a valuable prognostic marker of tumors with low malignant potential and can be used as surrogate marker for the detection of genetically stable bladder tumors.     

Correlations between p53-protein accumulation, serum antibodies and gene mutation in colorectal cancer.

Only half of colorectal-cancer patients elicit serum antibodies in response to intratumoral p53-gene mutations. Our study was designed to compare cellular events (p53-protein accumulation and gene mutations) with the presence of circulating anti-p53 antibodies (p53-Ab). Thirty-five colorectal-cancer patients were studied for their intratumoral p53-protein accumulation and circulating p53-Ab. Tumour DNA was analyzed for genomic mutations in a sub-set of 28 patients. In all, 18 tumours (51.4%) were positive by immunohistochemistry, and 17 tumour extracts were shown to contain "mutant" conformation p53 protein, 16 of them being were concordant by both methods. Of the 28 tumours tested by DGGE, 16 contained alterations in p53 exons 5 to 8 (57.1%). Of 12 tumours without detectable mutations, 10 were "mutant"-conformation-negative by immunohistochemistry and ELISA. Paradiploid tumors presented more frequently wild-type p53 genes and were significantly less frequently immunohistochemistry- or p53-Ab-positive than polyploid tumors. Circulating p53-Ab were detected in the serum of 11 patients (31%). In 9/11 cases, a gene mutation was found in the corresponding tumour. Three of four mutations in exon 8 and 3/3 mutations in exons 5-6 were associated with p53-Ab, in contrast with only 3/9 mutations in exon 7. We found good agreement in the detection of p53-gene alterations by different methods. However, our data suggest that all gene mutations may not be equivalent in term of immunogenicity.     

Frequency of fibroblast growth factor receptor 3 mutations in sporadic tumours

Mutations in FGFR3 have been identified in several tumour types including bladder carcinoma, cervical carcinoma, and multiple myeloma. In bladder carcinoma, we recently identified FGFR3 mutations in 41% of tumours, making this the most frequently mutated putative oncogene identified in bladder cancer to date. We have now investigated the frequency of FGFR3 mutation in a panel of 125 tumours and 13 cell lines from various other organs. We analysed the mutation hotspots in exons 7, 10 and 15 by direct DNA sequencing, and found one mutation in exon 7 (S249C) in 1/28 (3.5%) cervical tumours. Mutations were not detected in stomach, rectum, colon, prostate, ovarian, breast, brain, or renal tumours, nor were they found in any of the cell lines included in this study. We conclude that FGFR3 is commonly mutated in bladder carcinoma and only rarely in cervical carcinoma. Several tumour types appear not to possess any mutations in FGFR3, suggesting that these mutations are important only in the development of certain types of tumour.     

P53 gene alterations in differentiated thyroid cancers

Analysis of 22 human thyroid cancers including papillary, follicular and medullary subtypes (PTC, FTC, MTC) by PCR-SSCP, and immunohistochemistry detected 4 deletions and 3 mutations. Deletions involved exons 1, 2-3 and 5-6 in 3 PTCs, mutations exons 2-3 in 2 MTCs and exons 8-9 in PTC4. p53 alterations occurred in 2/5 recurrent tumors and 2/3 tumors developing to cell lines. Immuno-histochemistry detected p53 mutations in differentiated areas of papillary thyroid cancers as frequent events occurring at stage T1 to T4 in contrast to prior findings by other authors which restrict p53 alterations to undifferentiated stages.