Occupational exposure to polycyclic aromatic hydrocarbons influenced neither the frequency nor the spectrum of FGFR3 mutations in bladder urothelial carcinoma

Occupational exposure to polycyclic aromatic hydrocarbons (PAH) is associated with an increased risk of urothelial carcinoma (UC). FGFR3 is found mutated in about 70% of Ta tumors, which represent the major group at diagnosis. The influence of PAH on FGFR3 mutations and whether it is related to the emergence or shaping of these mutations is not yet known. We investigated the influence of occupational PAH on the frequency and spectrum of FGFR3 mutations. We included on 170 primary urothelial tumors from five hospitals from France. Patients (median age, 64 yr) were interviewed to gather data on occupational exposure to PAH, revealing 104 non- and possibly PAH exposed patients, 66 probably and definitely exposed patients. Tumors were classified as follows: 75 pTa, 52 pT1, and 43 > or =pT2. Tumor grades were as follows: 6 low malignant potential neoplasms (LMPN) and 41 low-grade and 123 high-grade carcinomas. The SnaPshot method was used to screen for the following FGFR3 mutations: R248C, S249C, G372C, Y375C, A393E, K652E, K652Q, K652M, and K652T. Occupational PAH exposure was not associated with a particular stage or grade of tumors. Thirty-nine percent of the tumors harbored FGFR3 mutations. After adjustment for smoking, occupational exposure to PAH did not influence the frequency [OR, 1.10; 95% CI, 0.78-1.52], or spectrum of FGFR3 mutations. Occupational exposure to PAH influenced neither the frequency nor the spectrum of FGFR3 mutations and there was no direct relationship between these mutations and this occupational hazard.

Oncologic control obtained after exclusive flexible ureteroscopic management of upper urinary tract urothelial cell carcinoma

OBJECTIVE

To assess oncological outcome after first-line management of upper urinary tract urothelial cell carcinomas (UUT-UCCs) by exclusive flexible ureteroscopy.

MATERIALS AND METHODS

A retrospective review was performed for 35 patients treated between 2003 and 2007. All patients underwent retrograde flexible ureteroscopy for diagnosis, treatment (i.e., holmium:YAG vaporisation), and follow-up. The following data were reviewed: sex, age, ASA score, presence of a solitary kidney, unifocal or multifocal tumour, history of bladder cancer, tumour localisation, tumour size, stage and grade, outcome, recurrence, and progression.

RESULTS

The mean age was 67 + or - 13.1 years (range: 38-88). The tumour involved the renal pelvis and the caliceal system in 19 cases (54%), the ureter in 8 cases (23%), and both in 8 cases (23%). Twelve patients (34%) had a history of bladder carcinoma. Tumour stage was superficial in 63% (57% were pTa and 6% were pT1) and not available in 37%. Tumour grade was low, high, and unavailable in 49, 14, and 37%, respectively. The median follow-up was 30 months (range: 12-66), and 21 patients had a recurrence (60%). The median survival rate without recurrence was 10 months (95% CI [5-22]). Four patients underwent nephroureterectomy during follow-up. No patient died of disease progression. The main limitation was the limited length of follow-up.

CONCLUSIONS

Flexible endoscopic management can be advocated in selected cases of non-muscle invasive UUT-UCCs as an alternative to nephroureterectomy. Because of a high recurrence rate, long-term and stringent surveillance is needed, including iterative ureteroscopies at least every 3 months for 2 years.

Regional copy number–independent deregulation of transcription in cancer

Genetic and epigenetic alterations have been identified that lead to transcriptional deregulation in cancers. Genetic mechanisms may affect single genes or regions containing several neighboring genes, as has been shown for DNA copy number changes. It was recently reported that epigenetic suppression of gene expression can also extend to a whole region; this is known as long-range epigenetic silencing. Various techniques are available for identifying regional genetic alterations, but no large-scale analysis has yet been carried out to obtain an overview of regional epigenetic alterations. We carried out an exhaustive search for regions susceptible to such mechanisms using a combination of transcriptome correlation map analysis and array CGH data for a series of bladder carcinomas. We validated one candidate region experimentally, demonstrating histone methylation leading to the loss of expression of neighboring genes without DNA methylation.

Gefitinib Inhibits the Growth and Invasion of Urothelial Carcinoma Cell Lines in which Akt and MAPK Activation Is Dependent on Constitutive Epidermal Growth Factor Receptor Activation

PURPOSE

Abnormally high levels of epidermal growth factor receptor (EGFR) protein are associated with advanced tumor stage/grade. The objective of this study was to evaluate the effects of the specific EGFR tyrosine kinase inhibitor gefitinib on activation of the Akt and mitogen-activated protein kinase (MAPK) pathways in human urothelial cell carcinoma (UCC) cell lines and to identify potential markers of gefitinib responsiveness in biopsy samples of UCC.

EXPERIMENTAL DESIGN

Changes in markers of UCC growth and invasion after exposure to gefitinib were studied in six human UCC cell lines expressing various levels of EGFR. The findings were related to activation of Akt and MAPK. We studied the influence of gefitinib on intraepithelial expansion of the responsive 1207 cell line. EGFR, Akt, and MAPK activation was studied by Western blot analysis of a panel of 57 human UCC.

RESULTS

Gefitinib had a growth-inhibitory and anti-invasive effect in two of six UCC cell lines (i.e., 647V and 1207). Gefitinib was also able to block the expansion of 1207 at the expense of normal urothelial cells. These effects did not depend on the level of expression of EGFR but they were associated with the down-regulation of MAPK and Akt activity; in 1207 cells, gefitinib activity was associated with p27 up-regulation and p21 and matrix metalloproteinase-9 down-regulation. Similarly, the Akt and MAPK pathways were found to be strongly phosphorylated in association with EGFR activation in a subset of human UCC specimens.

CONCLUSIONS

Activation of EGFR, Akt, and MAPK defines a subset of UCC which might provide information for the identification of gefitinib responders.

Oncogenic properties of the mutated forms of fibroblast growth factor receptor 3b

Germinal activating mutations of FGFR3 are responsible for several forms of dwarfism due to the inhibitory effect of FGFR3 on bone growth. Surprisingly, identical somatic activating mutations have been found at the somatic level in tumours: at high frequency in benign epithelial tumours (seborrheic keratosis, urothelial papilloma) and in low-grade, low-stage urothelial carcinomas, and at a lower frequency in other types of urothelial carcinoma, in cervix carcinoma, and in haematological cancer, multiple myeloma. FGFR3 exists as two isoforms, FGFR3b and FGFR3c, differs in ligand specificity and tissue expression. FGFR3b is the main form in epithelial cells and derived tumours, whereas FGFR3c is the main form in mesenchyme-derived cells and multiple myeloma. Several lines of evidence suggest that mutated FGFR3c has transforming properties. Although mutated FGFR3b is mostly found in benign epithelial tumours or carcinomas of low malignant potential, we present evidence here that mutated FGFR3b is oncogenic. All bladder tumours presenting FGFR3 mutations expressed this receptor more strongly than normal urothelium or non-mutated tumours. NIH-3T3 cells transfected with a mutated form of FGFR3b--FGFR3b-S249C, the most common mutation in bladder tumours--presented a spindle-cell morphology, grew in soft agar and gave rise to tumours when xenografted into nude mice. We identified one line of 17 bladder cell lines tested (MGH-U3) that expressed a mutated form of FGFR3b, FGFR3b-Y375C. We showed using siRNA and SU5402, an FGFR inhibitor, that the tumour properties of MGH-U3 depended on mutated receptor activity. Thus, in two different models, mutated FGFR3b presents oncogenic properties.

Growth, differentiation and senescence of normal human urothelium in an organ-like culture

OBJECTIVE

To examine the kinetics of growth, differentiation and senescence of normal human urothelium in an organoid-like culture model.

MATERIALS AND METHODS

Micro-dissected normal human urothelium explants were grown on porous membranes pretreated with various matrix components. Between 5 and 30 days of culture, cell proliferation was assessed by BrdU incorporation. Differentiation was evaluated on the basis of cytokeratin (Ck) and uroplakin (UP) expression. Epidermal growth factor family mRNA expression was monitored during explant outgrowth. Senescence was assessed by measuring endogenous beta-galactosidase activity and p16(INK4a) mRNA expression.

RESULTS

Collagen IV was the most efficient matrix component for urothelial cell expansion. BrdU incorporation by urothelial cells was 5% between 15 and 30 days, corresponding to steady-state urothelium in vivo. Heparin-binding EGF (HB-EGF), Amphiregulin (AR) and Transforming Growth Factor alpha (TGF alpha) expression correlated with increased cell proliferation. UPII expression was stable throughout culture. P16(INK4a) mRNA expression and beta-galactosidase activity increased on day 25, giving signs of senescence.

CONCLUSIONS

This model retains many characteristics of the urothelium in vivo. It can be used for pharmacological studies between 15 to 25 days and to study mechanisms such as wound healing, proliferation and senescence.

Profiles of the 2 INK4a gene products, p16 and p14ARF, in human reference urothelium and bladder carcinomas, according to pRb and p53 protein status

The INK4a/ARF locus encodes 2 cell cycle regulatory proteins: p16 and p14(ARF). P16 inhibits the activities of cdks, which maintain the retinoblastoma protein (pRb) in its active hypophosphorylated state. P14(ARF) blocks MDM2-induced p53 degradation and transactivational silencing. In this study, we investigated the expression of p16 and p14(ARF) in reference human urothelium and in 51 urothelial carcinomas (UCs) of all stages and grades, by reverse transcription-polymerase chain reaction (RT-PCR). Patterns of p14(ARF) and p16 expression were compared with each other and then with patterns of p53 and pRb protein expression, respectively, as determined by immunohistochemistry. P14(ARF) and p16 mRNAs were present at low levels or were undetectable in reference urothelia and in most superficial tumors, whereas they were present at high levels in a subset of tumors of advanced stage and high grade. The expression profiles of these 2 mRNAs were correlated in all but 4 cases, indicating that the 2 INK4a products may have nonredundant functions. Forty-six of the 51 tumors (90%) presented changes to or a lack of activation of the p14(ARF)-p53 pathway and were p53 positive (n = 10), p14(ARF) negative (n = 23), or both p53 positive and p14(ARF) negative (n = 13), suggesting that these 2 components of the pathway may be altered or nonactivated. Markedly high levels of p16 mRNA (n = 5) were associated with the absence of pRb expression, with the exception of 1 case in which the p16 gene contained a deletion mutation. A lack of p16 mRNA or low levels of this mRNA were associated with pRb detection in all but 1 case. In invasive UCs, the p16-pRb pathway, the p14(ARF)-p53 pathway, or in many cases both pathways were altered or not activated, demonstrating the involvement of these pathways in invasive bladder tumorigenesis.

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.

Pretreatment p53 Nuclear Overexpression as a Prognostic Marker in Superficial Bladder Cancer Treated with Bacillus Calmette–Guérin (BCG)

INTRODUCTION

Altered p53 gene product correlates with the stage and grade of bladder tumor, but its value as a predictor of BCG response has been disappointing. In order to revisit the prognostic value of pretreatment p53 nuclear overexpression for the BCG response, we studied a large cohort of consecutive patients with superficial bladder cancer treated with BCG.

METHODS

From 1988 to 2001, 102 patients with a history of multifocal, recurrent, and/or high-risk papillary transitional cell carcinoma or carcinoma in situ, were treated for the first time with BCG. p53 immunostaining was performed on paraffin-embedded tissues using monoclonal antibody DO7 and an automated immunostainer. Special attention was paid to the conditions of tumor fixation. p53 overexpression was defined as more than 20% tumor cells with p53-stained nuclei.

RESULTS

Immunostaining was significantly higher for Ta/T1 G3 +/- Cis (p < 0.001), tumoral substage T1b (p = 0.001), grade 3 (p = 0.0001), and Cis (p = 0.002). Times to recurrence, progression and cancer death were shorter among patients with p53 overexpression (p = 0.03; p < 0.0001; p = 0.0003). In multivariate analysis, p53 overexpression was an independent predictor of recurrence (p = 0.0003) [RR = 0.15; 95%CI, 0.06 to 0.42].

CONCLUSION

Pretreatment p53 nuclear overexpression in superficial bladder tumors is associated with a high risk of disease recurrence, progression and cancer death after BCG therapy. Applying antibody DO7 with an automated immunostainer and stringent fixative conditions, p53 nuclear immunostaining yields clinically relevant information and may be a useful tool for selecting patients with superficial bladder cancer who might be resistant to BCG.

FGFR3 and TP53 gene mutations define two distinct pathways in urothelial cell carcinoma of the bladder

FGFR3 and TP53 mutations are frequent in superficial papillary and invasive disease, respectively. We used denaturing high-performance liquid chromatography and sequencing to screen for FGFR3 and TP53 mutations in 81 newly diagnosed urothelial cell carcinomas. Tumors were classified as follows: 31 pTa, 1 carcinoma in situ, 30 pT1, and 19 pT2-T4. Tumor grades were as follows: 10 G1, 29 G2, and 42 G3. FGFR3 mutations were associated with low-stage (P < 0.0001), low-grade (P < 0.008) tumors, whereas TP53 mutations were associated with high-stage (P < 0.003), high-grade (P < 0.02) tumors. Mutations in these two genes were almost mutually exclusive. Our results suggest that FGFR3 and TP53 mutations define separate pathways at initial diagnosis of urothelial cell carcinoma.