Chromosome changes in bladder cancer: clinical and other correlations

Bladder cancer

Bladder cancer is a global health issue with sex differences in incidence and prognosis. Bladder cancer has distinct molecular subtypes with multiple pathogenic pathways depending on whether the disease is non-muscle invasive or muscle invasive. The mutational burden is higher in muscle-invasive than in non-muscle-invasive disease. Commonly mutated genes include TERT, FGFR3, TP53, PIK3CA, STAG2 and genes involved in chromatin modification. Subtyping of both forms of bladder cancer is likely to change considerably with the advent of single-cell analysis methods. Early detection signifies a better disease prognosis; thus, minimally invasive diagnostic options are needed to improve patient outcomes. Urine-based tests are available for disease diagnosis and surveillance, and analysis of blood-based cell-free DNA is a promising tool for the detection of minimal residual disease and metastatic relapse. Transurethral resection is the cornerstone treatment for non-muscle-invasive bladder cancer and intravesical therapy can further improve oncological outcomes. For muscle-invasive bladder cancer, radical cystectomy with neoadjuvant chemotherapy is the standard of care with evidence supporting trimodality therapy. Immune-checkpoint inhibitors have demonstrated benefit in non-muscle-invasive, muscle-invasive and metastatic bladder cancer. Effective management requires a multidisciplinary approach that considers patient characteristics and molecular disease characteristics.

Radical Cystectomy for Bladder Cancer: The Case for Early Intervention

There are no prospective studies comparing early cystectomy versus cystectomy after failed conservative management in patients with high-risk superficial bladder cancer. In the absence of clinically proven biomarkers for predicting tumor biology and the response to therapy, the treatment decision must be individualized based on the high-risk features outlined herein. Assuming that all patients can be treated effectively with bladder-sparing regimens and safely salvaged at the time of failure or progression is dangerous. Data support the negative impact of a delay in cystectomy and argue for improvements in the timing of cystectomy despite the clinical absence of muscle invasion. Accordingly, high-risk patients with non-muscle invasive disease require vigilant follow-up and should be informed from the onset of the risk for progression and the possible need for cystectomy. Repeat resection before intravesical therapy in the patient with T1 tumor is advised and should help to improve, but will not completely eliminate, the problem of clinical under-staging. Among patients with CIS and recurrent high-grade non-muscle invasive tumors, repeat biopsies following intravesical therapy are encouraged to ensure treatment response. Although there is debate regarding the timing of early cystectomy for patients with high-risk non-muscle invasive bladder cancer, there is little doubt that, for muscle invasive disease, prompt cystectomy influences the effectiveness of this therapy choice. An unnecessary delay in the performance of radical cystectomy in patients with organ-confined bladder cancer compromises outcomes and risks potentially avoidable deaths from disease.

Detection of genetic alterations in primary bladder carcinoma with dual-color and multiplex fluorescence in situ hybridization

Cytogenetic studies of bladder cancer have shown several nonrandom aberrations. Numerical aberrations of both sex chromosomes were investigated in 32 primary bladder tumors with bicolor fluorescence in situ hybridization (FISH). Loss of chromosome Y and overrepresentation of chromosome X were observed in subgroups of male patients. Chromosome X was represented normally in female patients. Two of the above primary bladder tumors, a transitional cell carcinoma (TCC) and an adenocarcinoma, were further analyzed with both multiplex FISH (24-color M-FISH) and G-banding. Both cases exhibited 1) common breakpoints on 5q11 approximately q12 and 15q24; 2) involvement of the pericentromeric area of chromosome 13; 3) structural abnormalities of chromosomes 8 and 17, with loss of material on the short arm; 4) structural abnormalities involving chromosome 11; and 5) loss of chromosome Y. The TCC case also exhibited structural abnormalities of chromosome 9, resulting in loss of 9q. The combined G-banding and M-FISH findings could help reveal regions potentially involved in bladder tumorigenesis.

Evaluation of chromosome 8 and 11 aneuploidies in washings and biopsy materials of bladder transitional cell carcinoma

We compared chromosome 8 and 11 aneuploidies on bladder biopsy tumor tissues and bladder washing samples of transitional cell carcinoma (TCC) and their relationship to tumor malignancy. Interphase fluorescence in situ hybridization (FISH) was applied to nuclei of washing material and biopsy samples of 17 patients with TCC. Incidence of cells having aneuploidy was clearly nonrandom from patient to patient. There was no significant difference in the incidence of aneuploid frequency for chromosomes 8 and 11 between biopsies of bladder tumors and bladder washing samples (P > 0.05). For chromosome 8, incidence of disomic cells (having two signals) in grade III tumors was significantly lower than in grade II tumors of both washing samples (P = 0.004) and biopsy materials (P = 0.005), indicating a high frequency of aneuploidy. The incidence of nuclei with four or more than four signals of chromosome 8 was significantly higher in grade III tumors than in grade II tumors in washing samples (P = 0.031 and 0.003, respectively). Similarly, in biopsy material, the incidence of nuclei with more than four signals of chromosome 8 was significantly higher in grade III tumors than in grade II tumors (P = 0.004). For chromosome 11, in both washing samples and biopsy materials, the incidence of disomic cells (having two signals) in grade III tumors was significantly lower than that detected in grade II tumors (P = 0.031 and 0.014, respectively), indicating a high frequency of aneuploidy. In biopsy materials, the incidence of nuclei with three or four signals was significantly higher than that in grade II tumors (P = 0.014 and 0.012, respectively). These findings suggest that FISH analysis of bladder washing samples can be effectively detected as genetic changes of bladder tumors. It might predict genetic progression of these tumors, which might be related to tumor stage, because higher stages of tumors showed a higher incidence of aneuploidies of chromosomes 8 and 11.

Cytogenetics and molecular genetics of bladder cancer: a personal view

The cytogenetic and molecular genetic aspects that may be involved in the pathogenesis of bladder cancer are presented. Although anomalies of chromosome 9 may play an initial causative role in this cancer, the subsequent events, involving a succession of genetic changes, are less established or understood. This presentation is a distillation of what generally are considered to be the cytogenetic and molecular genetic events that constitute the array of changes underlying bladder cancer.

[Flow cytometric DNA analysis and cytology in diagnosis and prognosis of bladder tumors: preliminary results of a comparative study of bladder lavage]

OBJECTIVE

To compare flow cytometric data (ploidy and proliferative activity or percentage SG2M-phase cells) to cytologic and histologic data of the bladder carcinomas.

MATERIALS AND METHODS

Cytologic and flow cytometric analysis of DNA content were performed on 48 bladder washings: 28 bladder washings from patients being followed for urothelial carcinomas and 20 control washings from individuals undergoing cytoscopy for other reasons.

RESULTS

Cytological sensitivity and specificity of bladder washing were 75% and 91% respectively. Specificity was increased to 94% using flow cytometric DNA analysis whereas sensibility was moderately decreased to 68%. Combination of flow cytometry and cytology increased the diagnostic yield to 100%. The study of the patient group showed an increased abnormalities (aneuploidy and/or proliferate activity SG2M > 10%) according to the tumor grading and tumor staging. A cytometric test was positive in 80% for G3 tumours and in 68% for G2 tumours. The staging tumor was positive in 46%, 89% and 100% of the pTa-pT1, pT2 and pT4 tumours respectively. Otherwise the comparison of control group with patients showed a statistical correlation between cytometric test, staging tumour and tumoral grading as showed in the following groups: control/G1-G2 (p < 0.05), control/G3 (p < 0.001), control/pTa-pT (p < 0.05), control/pT2-pT4 (p < 0.001).

CONCLUSION

We confirmed through this study the interest of the flow cytometric DNA analysis in the diagnosis and prognosis of bladder carcinomas, and we showed the importance of the histogram classification in order to facilitate their interpretation and to avoid the trap of false aneuploidy.

Lower incidence of urothelial cell carcinoma due to the concept of a clonal origin

Synchronous and metachronous tumours are frequently observed in the urinary tract and may be explained by the concept of field cancerisation, i.e. exposure to carcinogens leads to independent transformation of many urothelial cells resulting in genetically unrelated tumours. However, increasing evidence supports the concept of clonality, i.e. the progeny of a single transformed cell spreads through the urinary system resulting in genetically related tumours. The aim of this study was to review the molecular biological evidence for both concepts and to assess the consequences of a clonality assumption on the incidence of urothelial cell carcinoma (UCC). In total 1198 non-invasive and 1113 invasive (> or = T1) UCCs of the bladder were registered as incident tumours in 1996-1997 by three Dutch cancer registries following the current registration rules of the International Association of Cancer Registries (IACR). Assuming clonality, the number of non-invasive and invasive bladder UCCs decreased by 10.9% and 11.5% respectively. A decline of 8.5% and 9.5% was found for UCCs of the ureter and renal pelvis, respectively. Current registration rules have substantial impact on the incidence estimates of UCC. New insights into the molecular biology of UCC should be translated into registration rules.

Chromosomal abnormalities in two bladder carcinomas with secondary squamous cell differentiation

Two secondary squamous cell carcinomas of the bladder (i.e., tumors that originated from primary transitional cell carcinomas) were examined cytogenetically. Both tumors showed complex karyotypes with many of the same aberrations that have formerly been described in transitional cell carcinomas. Monosomy 9, trisomy 7, and rearrangements of chromosomes 3, 8, 10, 13, and 17 were common to both tumors. Among other changes that have been implicated in bladder carcinogenesis, an isochromosome for 5p was seen in one tumor and loss of 11p material in the other. Our findings indicate that secondary squamous cell carcinomas of the bladder are karyotypically indistinguishable from advanced transitional cell carcinomas of the same organ. The putative genetic changes that steer the differentiation of the neoplastic epithelium in the direction of squamous cells thus remain unknown.

Nonrandom gain of chromosome 7 in central neurocytoma: a chromosomal analysis and fluorescence in situ hybridization study

Central neurocytoma is a benign, slow-growing neoplasm with favourable prognosis. Biomolecular analysis has failed to demonstrate significant alterations, and no cytogenetic alterations have been reported. In this study we demonstrate chromosome 7 gain in three of nine neurocytomas (33%). Traditional cytogenetic analysis performed in four of the nine cases identified trisomy 7 as the sole chromosomal abnormality in one case. Interphase cytogenetics utilizing fluorescent in situ hybridization (FISH) on cell suspensions from formalin-fixed paraffin-embedded tumour tissue performed in all nine cases detected trisomy 7 in two more cases and tetrasomy in another. Our results suggest that chromosome 7 gain is a feature of neuroectodermal tumorigenesis, possibly conferring growth advantage on the neoplastic cells. FISH on interphase nuclei is a valuable adjunct in the genetic evaluation of rare central nervous system neoplasms with low baseline proliferative activity.

Loss of chromosome 9 in tissue sections of transitional cell carcinomas as detected by interphase cytogenetics. A comparison with RFLP analysis

Interphase cytogenetics by in situ hybridization (ISH) using a panel of centromere-associated DNA probes for chromosomes 1, 7, 9, 10, 11, 16, 17, and 18 was performed on 5 microns thick frozen tissue sections of transitional cell carcinomas (TCCs) of the urinary bladder. By this approach, chromosome ploidy, numerical chromosome aberrations, imbalance between chromosomes, and heterogeneity of aberrations within individual tumours were determined. In 15 of 24 TCCs, loss or underrepresentation of chromosome 9, compared with the ISH copy numbers of at least five other chromosomes, was demonstrated. Independently, RFLP analysis were performed on the same cases to detect loss of heterozygosity (LOH) of chromosome loci 9q34, 11p15, 16q22-24, 17p13, and 18q21. LOH was found in 9 of 19 informative cases for chromosome locus 9q34. Comparison of the ISH and RFLP results showed no correlation between numerical aberration and LOH for the loci on chromosomes 11, 16, 17, and 18. However, numerical loss of chromosome 9 was found in 89 per cent (eight of nine cases) with LOH for 9q34. Conversely, LOH at 9q34 was observed in only 67 per cent (eight of 12 cases) with underrepresentation of chromosome 9. Moreover, in 60 per cent of the non-informative cases (three of five cases), underrepresentation for chromosome 9 was observed. These results indicate that the heterochromatin probe for chromosome 9 can be reliably used in TCC tissue sections for the detection of chromosomal loss. In aneuploid TCCs, this DNA probe can be used for the detection of chromosomal underrepresentation only in combination with other centromere-associated DNA probes.

Molecular detection of primary bladder cancer by microsatellite analysis

Microsatellite DNA markers have been widely used as a tool for the detection of loss of heterozygosity and genomic instability in primary tumors. In a blinded study, urine samples from 25 patients with suspicious bladder lesions that had been identified cystoscopically were analyzed by this molecular method and by conventional cytology. Microsatellite changes matching those in the tumor were detected in the urine sediment of 19 of the 20 patients (95 percent) who were diagnosed with bladder cancer, whereas urine cytology detected cancer cells in 9 of 18 (50 percent) of the samples. These results suggest that microsatellite analysis, which in principle can be performed at about one-third the cost of cytology, may be a useful addition to current screening methods for detecting bladder cancer.

La citogenetica e la genetica molecolare nella prognosi del carcinoma della vescica: Cytogenetics and molecular genetics in bladder carcinoma prognosis

The use of cytogenetics in the characterization of bladder tumours has made it possible to demonstrate that chromosomal alterations are correlated with stage and grade of the tumour and have a predictive value as regards both tumour recurrences and progression. In the last decade the chromosomes involved in the main aberrations have been identified, and a negative prognostic significance has been suggested for some chromosomal aberrations. The knowledge of cytogenetics has been deepened by the sophisticated methods of molecular genetics, that have discovered many oncogenes and suppressor genes probably involved in the development of bladder tumours. The most characteristic molecular alterations of these tumours are losses of genetic information on chromosomes 9, 11 and 17, as a consequence of deletions and/or mutations. Such alterations probably cause the loss and/or the inactivation of suppressor genes (partly hypothetic still) and could represent important predictive factors of tumour progression.

Near-diploid karyotypes with recurrent chromosome abnormalities characterize early-stage endometrial cancer

Cytogenetic investigation was attempted on 15 endometrial tumors. Whenever possible, a combination of direct harvesting and short-term culture (with or without prior methotrexate synchronization) was used. The analysis was successful in 13 cases: 12 carcinomas of stage I and one atypical hyperplasia. Clonal abnormalities were found in 10 tumors, whereas the remaining three showed a normal karyotype. The modal chromosome number was near-diploid. The abnormal karyotypes contained relatively simple numerical or structural aberrations in all but one tumor, a serous papillary carcinoma with multiple complex changes as well as cytogenetic evidence of intratumor heterogeneity. Gain of 1q, trisomy for chromosomes 2, 7, 10 (this trisomy was shown by in situ hybridization to be present also in a large number of interphase cells), and 12, and loss of chromosome 22 were recurrent aberrations; these are also the cytogenetic anomalies that have been consistently associated with endometrial carcinomas in previous studies. The utilization of both direct harvesting and short-term culture in several cases increased the frequency with which abnormal karyotypes were found; sometimes aberrations were found by the first method but not by the other, and vice versa. Never were different clonal anomalies found by the two approaches in the same case. Synchronization of the cultures generally led to chromosome preparations with more mitoses and of better quality. Again, no different anomalies were found in synchronized and standard cultures from the same tumor.

A new approach in the diagnosis and follow-up of bladder cancer. FISH analysis of urine, bladder washings, and tumors

The aim of the present study was to ascertain whether fluorescence in situ hybridization (FISH) of urine could be a useful approach in bladder cancer. Herein, we present the cytogenetic and FISH findings in patients with and without bladder cancer. The samples examined with FISH consisted of urine, bladder washings, and tumor tissue, when available. The results obtained show that the FISH technique, particularly when used on urine, is a very useful tool in the diagnosis, early detection, and management of bladder cancer.

The numerical aberrations of chromosome 7 detected by fluorescence in situ hybridization in human breast cancers

The relationship between the numerical aberrations of chromosome 7 in interphase cells and the clinicopathological behavior of breast tumors was investigated in 51 touch imprinted preparations of breast tumors. Using fluorescence in situ hybridization with a chromosome 7-specific DNA probe, the fluorescein-isothiocyanate (FITC) spots mean and the representative copy number of each breast tumor were examined. The FITC spots mean (2.34) of 40 breast cancers increased compared with that of 11 benign lesions (1.98) (P < 0.02). The FITC spots mean tended to increase with the advancing stage and tumor size of the breast cancer. The FITC spots mean in the case with metastasis was also of a higher value than that without metastasis (P < 0.01). Furthermore, the existence of trisomy or over-trisomy of the copy number was related to the advancing stage and tumor size (P < 0.05 and P < 0.01, respectively). These findings suggest that the FITC spots mean and polysomy of the number of chromosome 7 may be highly predictive for breast tumor aggressiveness.

Cytogenetic analysis of a benzpyrene induced osteosarcoma in the rat (Rattus norvegicus)

A cytogenetic comparison of primary and transplant tumor cell-lines, both originating from a benzpyrene induced osteosarcoma, with normal rat cell-lines (Rattus norvegicus) is presented here. In all tumor cell-lines tested, the number of chromosomes was increased by one or two. Using Giemsa-banding, structural chromosomal changes, i.e. a Robertsonian translocation t(4;4)(q10;q10) and an interstitial deletion del(6)(q11q16) could be recorded. Furthermore, staining of nucleolus organizer regions (NORs) revealed a shift in NOR activity from chromosome number 11 to 12 and a decrease in NOR activity at chromosome number 3.

Concordance between karyotyping and in situ hybridization procedures in the detection of monosomy 9 in bladder cancer

Twenty-three cases of transitional cell carcinoma (TCC) with a diploid model chromosome count as selected after karyotyping were analyzed by fluorescence in situ hybridization (FISH), using a probe for the heterochromatic region of chromosome 9. A monosomy for chromosome 9 was detected in 50% by karyotyping and after FISH in 52% of the cases. A full concordance between FISH and conventional karyotyping was found. We concluded that FISH can be reliably applied to interphase nuclei of TCC for the detection of numerical chromosome 9 aberrations.

Identification of numerical chromosome aberrations in archival tumours by in situ hybridization to routine paraffin sections: evaluation of 23 phaeochromocytomas

We have applied non-isotopic in situ hybridization (ISH) to interphase cell nuclei of 23 phaeochromocytomas (18 primary and 5 metastatic tumours) within routine paraffin-embedded tissue sections. Each tumour was screened for numerical aberrations with a defined alphoid repetitive DNA probe set containing DNA probes specific for chromosomes 1, 7, 15, and Y. Normal adrenal medullas and other normal human cell types served as cytogenetic controls. Preservation of tissue morphology enabled targeted analysis of tumour cells. The presence of numerical chromosome changes in the tumour cells could easily be evaluated by comparing the ISH results of the DNA probes. Numerical abnormalities not previously reported in this neoplasm included overrepresentation of chromosomes 1 and 7, loss of chromosome 15, and both gain and loss of chromosome Y (P values < 0.01). The percentage of aneuploid cell nuclei in a tumour correlated well with the percentage of cells in the 4C peak of flow cytometric DNA histograms from these neoplasms. We conclude that interphase ISH can be used for the identification of new and reported cytogenetic changes in tumour cell nuclei within archival tissue sections. This novel procedure also allows for retrospective analysis of previously not karyotyped material.

Heterogeneity in bladder cancer as detected by conventional chromosome analysis and interphase cytogenetics

Thirty transitional cell carcinomas (TCCs) of the bladder were examined by classical chromosome counting to establish range, modal number, and percentage of metaphases with 2n, 3n, 4n, and > or = 5n chromosomes. In addition, fluorescence in situ hybridization (FISH) was applied to interphase nuclei to detect the percentage of tumor cells showing polyploidization and chromosome imbalance. In FISH, centromere-specific DNA probes for chromosomes 1, 7, 9, and 11 were used. The tumors were analyzed flow cytometrically to determine the DNA index (DI). Fourteen of 21 cases (67%) having a DI = 1 showed, after classical chromosome counting, in addition to a diploid model number, some cells with a 3n and 4n chromosome count. With FISH, eight cases (38%) showed a low percentage of cells with multiple signals for each of the probes, thus indicating polyploidization. In 13 (62%) cases, an imbalance between different chromosomes was detected. In nine tumors having a DI of 1.6 to 1.9, classical chromosome counting showed low percentages of > or = 5n cells in four cases, in addition to a triploid modal number. With FISH in six cases, a low percentage of cells showed five or more signals for each of the chromosomes, indicating polyploidization. In all cases, a chromosome imbalance was detected. With classical chromosome counting not all tumors can be analyzed. With FISH, small percentages of polyploid cells are not recognized. Both methods complement each other in that chromosome counting allows readier detection of heterogeneity in DNA-diploid tumors after polyploidization, whereas FISH allows efficient recognition of the chromosomes involved in the process of imbalance.

Cytogenetic findings in pituitary adenoma: results of a pilot study

Pituitary adenomas are the most common tumors of the sellar region and are, with rare exception, benign neoplasms. The natural history of these lesions is only poorly understood and, although histologic, immunocytologic, and ultrastructural characteristics have been well established, predicting the natural history of individual tumors is, at best, unreliable. In an effort to better characterize pituitary adenomas, we have analyzed the karyotypes of 18 surgical specimens and attempted to correlate with the morphologic appearance and the clinical data, for example, endocrinologic subtypes, histology, and tumor invasiveness. Most hormonal subtypes were studied including seven growth hormone-prolactin (GH-PRL), two Prolactin (PRL), two Adrenocorticotrophin (ACTH), seven nonsecretory (NULL). No correlations with morphology or invasiveness could be made. Of 7 null cell adenomas, five (71%) had normal karyotypes, whereas of 11 hormone-secreting adenomas three (28%) were normal. Of seven tumors with mixed GH-PRL activity, six had abnormal karyotypes. At least three chromosomes harbored abnormalities shared by more than two tumors. The results demonstrate that chromosome abnormalities are also found in benign tumors. These findings, however, suggest that hormone-secreting adenomas may be more likely to be associated with karyotypic abnormalities especially those of the GH-PRL variety. Genetic abnormalities associated with chromosomes 1, 4, 7, and 19 were common and warrant further investigation.

Significance of trisomy 7 in thyroid tumors

Standard cytogenetic studies of a multifocal metastasizing papillary thyroid carcinoma revealed two clonal chromosome aberrations: rearranged 10q and trisomy 7. Trisomy 7 seemed to be restricted to tumor nodule A, whereas era (10q) was detected in tumor nodule B and in a metastatic lymph node. We applied fluorescent in situ hybridization to ask whether trisomy 7 was a feature of the original tumor nodule or an in vitro phenomenon changing quantitatively during early passages and to see whether trisomy 7 was restricted to tumor nodule A. We used the biotinylated chromosome 7 alpha-satellite probe D7Z1 on freshly dropped slides from metaphase harvests from tumor nodule A,B, and the lymph node and on touch preparations from the frozen specimen of tumor nodule A. Trisomy 7 was present in the original tumor nodule (6% of cells), as well as in early passages (P1-3) from both tumor nodules and the metastatic lymph node with a frequency of 10.7-13.2%. The detection of trisomy 7 as a stable component in short-term cell culture and its presence in the original tumor material indicates that this common numerical aberration is an in vivo phenomenon.

Chromosome number correlates with survival in patients with malignant pleural mesothelioma

Modal (MO) and mean (ME) chromosome numbers determined by cytogenetic analysis were compared with survival in 34 patients with diffuse malignant pleural mesothelioma. The patients with normal chromosome number and no clonal abnormalities (MO = 46) survived longer (median survival 17 months) than patients with clonal abnormalities. MO greater than 46 correlated with shorter survival (median 12 months) (p = 0.0186). The correlation was more clear between mean chromosome number (ME) and survival: the median survival of patients with ME greater than 46 was 13 months whereas that of the patients with ME less than 46 was 26 months and ME = 46 (normal chromosome number and no clonal abnormalities) 31 months (p = 0.0007). Furthermore, there was a tendency of an association between ME = 46, ME less than 46 and epithelial subtype reported to be associated with a favorable prognosis in mesothelioma. The addition of chromosome material may present a mechanism to enhance expression of genes important in the pathogenesis of mesothelioma and lead to more aggressive behavior of the tumor.

Cytogenetic studies in 45 pediatric brain tumors

Brain tumors are the most frequent childhood tumors. There have been few cytogenetic studies published on these tumors in children compared to the numerous studies on adult brain tumors. We examined chromosomes from 45 primary pediatric brain neoplasms including 14 medulloblastomas, 12 astrocytomas, 4 glioblastomas, 7 ependymomas, 5 craniopharyngiomas, 2 meningiomas, and 1 ganglioglioma. Chromosomal abnormalities were found in 10 medulloblastomas out of the 14 analyzed. The most frequently observed abnormalities were the total or partial loss of one chromosome 17: monosomy 17, i(17q), and a monosomy 22 in 4 cases of desmoplastic medulloblastoma. In glioblastoma, we observed the gain of chromosome 7, chromosome 3, a monosomy 10, and hyperdiploidy. The loss of chromosome X was observed in 2 cases of ependymoma as was a monosomy 22. Our observations show that from the cytogenetic point of view childhood brain tumors differ from adult brain tumors.

Detection of DNA alterations in human bladder tumors by DNA fingerprint analyses

DNA fingerprint analyses were used to examine the constitutional and tumor DNA from 22 bladder tumor patients. DNA alterations, such as loss of bands, new bands, and intensity shifts were observed in 10 of the 22 patients. The most frequent DNA alteration, occurring in 80% of the patients, was a complete loss of one or several bands. Fingerprint abnormalities were present both in low-malignant superficial tumors and in high-malignant invasive tumors, but were also lacking in the latter group. Apparently no relationship exists between fingerprint abnormalities and gross chromosomal aberrations or the proportion of S-phase cells as measured by flow cytometry or development of recurrent tumors during a limited observation period. Thus, whether fingerprint aberrations express genetic alterations directly involved in the malignancy potential of bladder carcinoma remains an open question.

Chromosome losses in tumorigenic revertants of EJ/ras-expressing somatic cell hybrids

Tumorigenic transformation of SV40-immortalized human uroepithelial cells (SV-HUC) after transfection with EJ/ras was previously reported to be a rare event. To test the hypothesis that ras transformation requires loss of suppressor genes, somatic cell hybrids were generated between a rare tumorigenic transformant and an isogeneic nontumorigenic EJ/ras transfectant obtained in the same experiment. Both parental cell lines, as well as all hybrid progeny, expressed mutant p21 ras protein, but injections of three such independent hybrids into athymic nude mice at passage (P) 4 demonstrated that tumorigenicity was suppressed at 20 of 22 sites. Two tumors developed, after a relatively long 17-week latent period, as compared with a 4-week latent period for the tumorigenic parent. All three hybrids produced tumors at P8, but these showed different latent periods (3-14 weeks). Revertant hybrid tumors were high-grade carcinomas. Cell lines derived from these tumors expressed mutant p21 ras and retained at least 1 EJ/ras integration site. Karyotypic analysis of six independent hybrid tumor revertants showed that each had a unique clonal karyotype. Losses of two or more homologues of 1p, 3p, 4, 8, 10p, 11p, 13q, and 18 were identified in one or more tumorigenic revertants. Losses of all these chromosomes were previously associated with transformation of SV-HUC by EJ/ras, but were also associated with chemical transformation of SV-HUC in tumors that did not express mutant ras. Genetic losses involving most of these chromosomes have also been identified in clinical bladder cancers (i.e., 1p, 3p, 8, 11p, 13 and 18q). These data show that expression of EJ/ras does not negate or significantly alter requirements for multiple genetic losses in HUC tumorigenesis.

Clonal origin of bladder cancer

BACKGROUND

Patients with cancer of the urinary bladder often present with metachronous tumors, appearing at different times and at different sites in the bladder. This observation has been attributed to a "field defect" in the bladder that allows the independent transformation of epithelial cells at a number of sites. We tested this hypothesis using molecular genetic techniques.

METHODS

We examined 13 tumors from cystectomy specimens from four women, using a method that analyzes the pattern of X-chromosome inactivation to determine whether the tumors were derived from the same precursor cell. In addition, we analyzed allelic loss on autosomes to determine whether different tumors had the same genetic alterations. The alterations evaluated included the loss of chromosome 9q sequences (commonly found in superficial bladder tumors) and the loss of 17p and 18q sequences (usually found only in advanced tumors).

RESULTS

For each patient studied, all the tumors had inactivation of the same X chromosome, whereas normal bladder mucosa cells had random patterns of inactivation. Moreover, each tumor that could be evaluated from a given patient had lost the same allele on chromosome 9q, suggesting that the loss of this allele preceded the spread of neoplastic cells elsewhere in the bladder. The losses of chromosome 17p and 18q alleles, which are late events in tumor progression, were not common to different tumors from the same patient.

CONCLUSIONS

A number of bladder tumors can arise from the uncontrolled spread of a single transformed cell. These tumors can then grow independently with variable subsequent genetic alterations.

Nonrandom chromosome losses in tumorigenic revertants of hybrids between isogeneic immortal and neoplastic human uroepithelial cells

Somatic cell hybrid analysis was used to examine the role of recessive cancer genes in tumorigenic transformation in vitro of human uroepithelial cells (HUC). Hybrids between nontumorigenic pseudodiploid SV40-immortalized HUC (SV-HUC) and two aggressive grade III transitional cell carcinomas (TCC) produced in nude mice after in vitro exposure of SV-HUC to 3-methylcholanthrene (MC) were completely suppressed for tumorigenicity at early passage. Tumorigenic reversion occurred after five or more passages in culture and was always accompanied by chromosome losses. Overall, the tumorigenic revertants showed statistically significant losses of chromosomes 1, 4, 5, 9q, 12, 14q, and 17 (all P less than or equal to 0.05) as compared to losses in suppressed hybrids. In addition, hybrid reversion was accompanied by losses that left specific tumors with a single remaining homolog of certain chromosomes (i.e., 3, 5q, 11p, 17p, and 18q). These losses were also considered significant because of the likelihood that genes on these chromosomes were reduced to homozygosity. Many of the significant losses (i.e., 5q, 9q, 11p, and 17p) were of chromosomes that are frequently lost in clinical TCC. Thus, these results support the hypothesis that these chromosomes contain genes whose loss leads to HUC tumorigenesis.

Subgroups of uterine leiomyomas based on cytogenetic analysis

Chromosomes from 39 cases of benign uterine leiomyomas were studied. Consistent chromosomal abnormalities were detected in 15 cases (38.5%). Abnormalities involving chromosomes 12 and 14 with or without additional chromosomal changes were found in five cases (12.8%). Deletion of chromosome 7 was detected in five cases; in three cases (7.6%), this was the only abnormality present. Complex translocations involving X, 5, and 14 as well as X, 3, and 14 were observed in one case each. Insertion of a portion of chromosome 4 to chromosome 1, deletion involving chromosome 3, and nonreciprocal translocation between chromosomes 14 and 15 were observed in one case each. Monosomy 22, with a derived chromosome 14, was observed in one case. Trisomy 7 was also identified in one case. The structural and numeric abnormalities involved chromosomes X, 1, 2, 3, 4, 5, 6, 7, 9, 10, 12, 13, 14, 15, and 22. A normal 46,XX stem line with one or two abnormal cells was observed in 20 cases. Only normal karyotypes were obtained in the remaining four cases. A review of the literature and the results of our study indicate that uterine leiomyomas may be divided into eight groups based on cytogenetic analysis.

Unstable chromosome aberrations in bladder and renal cell carcinoma

Structural chromosome aberrations were investigated in 18 bladder carcinoma and 14 renal cell carcinoma patients. Unstable chromosome aberrations, such as breaks, gaps, minutes, and fragments, appeared in varying proportion. Double minutes (dmin) were also observed. In bladder carcinoma, 10 kinds of aberration were observed in 38.8% of the metaphase analyzed, and, in renal cell carcinoma, 7 kinds of aberrations were observed in 15.0%. The frequency of chromosome aberrations observed, and the occurrence of dmin and of aneuploidy, were correlated positively with histopathological grade and stage. From the results obtained here, we conclude that study of chromosome aberrations should be added as one of investigations for evaluating the malignant potential of the tumors.

Allelic 3p deletions in high-grade carcinomas after transformation in vitro of human uroepithelial cells

Restriction fragment length polymorphism (RFLP) analysis for allelic losses on the chromosome arm 3p were performed on independent carcinomas produced in athymic nude mice after transformation in vitro of a pseudodiploid clonal SV40-immortalized human uroepithelial cell line (SV-HUC). We analyzed ten primary carcinomas with heterogeneous phenotypes for deletions on 3p by using three informative probes, D3S30, D3S2, and D3F15S2, which map to the 3p11-p14, 3p21.1, and 3p21 regions, respectively. Five of the ten primary cancers showed reduction to homozygosity with at least one of the probes, and all five cancers were high-grade and poorly differentiated. We also analyzed six carcinomas that arose after progression of low-grade cancers, either spontaneously or after exposure to a human bladder carcinogen, to higher grades (progressed carcinomas). Four of the six exhibited 3p allelic loss. No preferential loss of a specific 3p allele was observed in any of the carcinomas. In addition, whereas most of the carcinomas showed allelic loss for all three of the probes, indicating a large-scale deletion, several of the carcinomas exhibited losses for only one or two of the probes, thus making it possible, along with the cytogenetic data, to define the least common region of deletion to 3p13----p14.2. These results support the hypothesis that nonrandom loss of a gene or genes on 3p leads to the development of cancer. Furthermore, these findings associate deletion of a putative 3p13----p14.2 tumor suppressor gene region with the development of high-grade uroepithelial carcinomas.

Specific chromosome change associated with acquisition in vivo of tumorigenicity in carcinogen-induced rat urinary bladder carcinoma cells

The correlation between chromosomal changes and tumorigenic potential of rat bladder epithelial cells was investigated. Seven cell lines were established from neoplastic urothelial cells derived from heterotopically transplanted rat bladders treated with topical application of one of two carcinogens, N-methyl-N-nitrosourea (MNU) or N-hydroxy-N-glucuronosyl-2-aminofluorene. Loss of the short arm of chromosome 3 was demonstrated in three of four lines tumorigenic in the nude mouse, but in none of three nontumorigenic lines. One of the three nontumorigenic cell lines (D44c) was treated further in vitro with MNU. All six tumorigenic, but none of the four nontumorigenic, morphologically altered cell lines derived from D44c demonstrated loss of the short arm of chromosome 3. These results suggest that chromosome 3 alterations may be associated with the tumorigenicity of carcinogen-induced rat bladder epithelial cells.

Chromosomal changes in thyroid tumors. Relation with DNA content, karyotypic features, and clinical data

A cytogenetic study was performed in 63 thyroid tumors after a monolayer short-term culture. Clonal chromosomal changes were found in 47% of carcinomas and 31% of adenomas. Chromosome 7 was altered in 40% of cytogenetically abnormal tumors. The modal DNA index measured in 26 tumors was consistent with the chromosomal mode in 88% of cases. A quantitative morphometric analysis of nuclear features differentiated between diploid thyroid adenomas with or without a single translocation, which suggests that they have different biological properties. Clonal chromosomal changes were observed in 78% of carcinomas with an aggressive behavior, but only 28% of those had no risk factors. The two patients who died early had abnormalities of chromosome 7.

Apparent correlation of sex chromosome loss and disease course in urothelial cancer

In recent years, interest in the genetics of various solid tumours has increased dramatically. Over the last several years, our laboratory has pursued genetic studies of transitional cell carcinoma of the bladder. We have studied the cytogenetics and disease course of more than 100 patients, achieving successful cultures in more than 75%. In these patients, we observed the loss of a sex chromosome (either X or Y) with a frequency of 40%. We stratified patients with loss of sex chromosomes into three groups: 1) presence of markers or chromosome rearrangements, 2) aneuploidy without marker chromosomes, and 3) loss of a sex chromosome only. The relevancy of both the natural history and potential impact of sex chromosome loss to the disease course, including invasive potential, will be discussed in detail for each of the three groups.

Trisomy 7 may be a primary change in noninvasive transitional cell carcinoma of the bladder

We describe two cases of transitional cell carcinoma of the bladder associated with trisomy 7. In one of them, trisomy 7 was the only chromosome abnormality observed. In the second case, trisomy 7 was found in 25 (80.6%) of the metaphases; in two of them this was the only anomaly, while in three metaphases trisomy 8 was also present, and in other two trisomy 10 was also observed. Our results suggest that trisomy 7 could be a primary change in TCC, and a review of the literature indicates that when it is present as the sole karyotypic abnormality is may be associated with a non-invasive behavior of the tumor.

Molecular genetics of human bladder carcinomas

Bladder cancer corresponds to a tumor type whose clinical behavior is difficult to predict. A better understanding of this pathology is expected from molecular genetics, which brings together cytogenetics and molecular biology. Therefore, we have tried to overview correlations between chromosome abnormalities and the presence, in the vicinity of the altered loci, of genes (oncogenes and others) that could be involved in bladder oncogenesis and/or tumor progression. In addition to oncogene activation by point mutations, gene amplification, or deregulation of gene expression, several cytogenetic as well as molecular evidences point to genetic deletions (existence of "tumor suppressor genes") being involved in those processes.

Absence of structural alterations of the multidrug resistance genes in transitional cell carcinoma

Tumor DNA from 27 patients with treated or untreated transitional cell carcinomas of the urinary tract was screened for genomic alterations of the multidrug resistance genes in order to determine whether structural changes of these genes are important in primary urothelial tumors. None of the tumors showed evidence of amplification or rearrangements of either mdr1 or mdr2. The lack of amplification or rearrangements observed in these tumors suggests that structural alterations of the mdr1 and mdr2 genes are not important mediators of drug resistance in TCC.

Chromosomal changes in renal cell carcinoma. No evidence for correlation with clinical stage

A cytogenetic study was performed in 18 renal cell carcinomas using a culture method previously described. The significance of chromosome involvement in clonal aberrations was evaluated according to the mean + 1 SD objective criterion. Chromosomes 3, 7, 9, and 17 were preferentially involved in both numerical and structural changes. The cytogenetic data have been correlated with the clinical staging, but in contrast to a previous study, abnormalities of chromosome 3 were not associated with a higher clinical stage.

Frequent clonal chromosomal changes in human non-malignant tumors

A cytogenetic analysis has been performed on 109 non-malignant human solid tumors of various histological types after short-term culture. These tumors were derived from epithelial, mesenchymal, embryonal and neurogenic tissues. The chromosome count was in the diploid range in virtually all specimens. Clonal chromosomal changes were found in 37% of tumors: 20% had numerical deviations, 12% structural rearrangements, and 5% both karyotypic alterations. Chromosome 7 was most frequently involved in 25% of abnormal specimens. Our results suggest that chromosomal changes contribute to non-malignant tumorigenesis and that their analysis may provide information about the genetic events which shift benign tumor cells to malignant behavior.

The cytogenetics of renal tumors. Where do we stand, where do we go?

In this review an attempt is made to give an overview of the present status of cytogenetic research in tumors of the kidney. The results of numerous studies in renal cell carcinoma and adenoma, transitional cell carcinoma, and renal oncocytoma are presented, and the findings from the literature, together with 52 current observations, are analyzed and evaluated with respect to their significance for the understanding of renal malignancies.