The cellular features of developing carcinoma in murine urinary bladder

[Karyometry of BBN-induced precancerosis of the urothelium : An experimental analysis]

BACKGROUND

The morphology of experimental precancerous lesions of the urinary bladder has been interpreted quite differently by various authors.

OBJECTIVES

The aim of this investigation was to quantify these lesions by karyometry and, thus, to gain a more reliable understanding of the process.

MATERIALS AND METHODS

A total of 60 Wistar rats were fed with N‑butyl-N-(4-hydroxybutyl)nitrosamine (BBN) at a concentration of 0.05 % in their drinking water to induce preneoplastic changes of the urothelium. After the second week of BBN exposition, 6 animals were killed every 2 weeks up to week 20. Smears of the scraped off urothelium of 3 urinary bladders of each group were analyzed cytologically and karyometrically.

RESULTS

BBN exposition led to statistically significant changes of the karyometric values using the χ² test to differentiate the control animals from the ones that had ingested BBN and the 2‑week groups from each other. These changes consisted mainly in significant deviations of the size of the nuclear area within the different groups.

CONCLUSION

Morphological and karyometrical analysis showed that biologically relevant stages in the development of chemically induced urothelial precancerous lesions could be realized much earlier than had been assumed in recent publications. Karyometric analysis offered a valid basis to describe the early morphologic alterations of carcinogenesis.

DNA cytophotometric and histological analysis of N-butyl-N-(4-hydroxybutyl)nitrosamine-induced precancerous lesions of the bladder urothelium

Purpose

The morphology of experimentally induced urinary bladder precancerous lesions has been differentially interpreted in the literature. Here, we aimed to describe the development of precancerous lesions of the urothelium histologically and by DNA cytophotometric analysis.

Methods

We induced precancerous lesions of the urothelium in 60 Wistar rats with 0.05 % N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) solution as drinking water. After exposure for 2–20 weeks, each animal received tap water for 2 weeks. Subsequently, six animals were killed every 2 weeks, and urothelia of three urinary bladders per time point were examined by DNA cytophotometry of smear preparations. An additional three urinary bladders were processed for histological analysis.

Results

Over 20 weeks, BBN exposure led to a significant difference between the control group and most of the BBN-exposed 2-week groups and to differences between most of these time point groups. After week 4, this difference included a higher proportion of cells with increased nuclear DNA content. At the end of the experiment, DNA cytophotometric values of the urothelium in experimental rats corresponded to those of poorly differentiated urothelial carcinomas.

Conclusions

Biologically significant stages of precancerous lesions were already detectable after 4 weeks of BBN exposure, considerably earlier than previously described in the literature.

Presence of CSE1L protein in urine of patients with urinary bladder urothelial carcinomas

The chromosome segregation 1-like (CSE1L) protein is highly expressed in most cancers and has been shown to be secreted by tumor cells. We studied the presence of CSE1L in the urine of patients with bladder urothelial carcinomas. The results of our immunohistochemical analysis showed a high expression of CSE1L in bladder cancer specimens, while the normal bladder specimens only showed a very faint staining in some cells. Immunoblotting showed that CSE1L was present in urine of patients with bladder cancer. Urinary CSE1L-positive cases were detected in 95% (57/60) of patients with bladder urothelial carcinomas or the atypical/suspicious cases with urothelial atypia. No CSE1L was detected in urine of healthy controls (p<0.01). Our results suggest that urinary CSE1L deserves further evaluation for the screening of bladder cancer.

Morphologic expressions of urothelial carcinoma in situ: a detailed evaluation of its histologic patterns with emphasis on carcinoma in situ with microinvasion

The recently proposed World Health Organization/International Society of Urological Pathology (WHO/ISUP) consensus classification of flat urothelial lesions expands the definition traditionally used for urothelial (transitional cell) carcinoma in situ (CIS), basing its diagnosis predominantly on the severity of cytologic changes. Lesions now encompassed within the diagnosis of CIS exhibit an array of cytologic and architectural features, which have not been documented in detail. In this study, cases were examined with respect to histologic patterns and microinvasion (invasion into the lamina propria to a depth of less than 2 mm). Five major patterns of CIS, often occurring in the same specimen (160 patterns in 77 cases), were noted. Common to each pattern was the presence of high-grade cytologic atypia, the definitional feature. The patterns found include 1) large cell CIS with pleomorphism (57%), in which the cells had abundant cytoplasm and nuclear pleomorphism; 2) large cell CIS without nuclear pleomorphism (48%); 3) small cell CIS (14%), in which the cytoplasm was relatively scant and pleomorphism was usually minimal; 4) clinging CIS (40%), in which the urothelium was denuded with a patchy, usually single layer of atypical cells; and 5) cancerization of urothelium (16%) with either pagetoid spread (clusters or isolated single cells) or undermining or overriding of the normal urothelium. Carcinoma in situ with microinvasion into the lamina propria (13 cases: 3 of 77 CIS cases studied above and 10 additional cases) was evident as invasive cells with retraction artifact mimicking vascular invasion (77%, 10 cases); nests, irregular cords, and strands, or isolated single cells with desmoplasia (8%, 1 case); or absent stromal response (15%, 2 cases). Although the diagnostic terminology for all of these patterns, for the purposes of the surgical pathology report, should be simply urothelial CIS with no specific mention of the morphologic pattern, awareness of the histologic diversity of CIS will facilitate the diagnosis of this therapeutically and biologically critical flat lesion of the urothelium. These lesions may be associated with microinvasion, which may be clinically unsuspected and histologically subtle.

Bladder. Risk and prognostic factors--a pathologist's perspective

Morphology remains a power tool to help predict the risk of recurrence, progression, and even response to therapy in bladder cancer. Nevertheless, more work is needed to refine and standardize criteria and terminology. Novel molecular tools may reveal prognostic factors, but these techniques must be compared with standard morphologic and clinical markers by performing multivariate analysis in a prospective fashion.

Superficial bladder carcinoma. Factors affecting the natural history

The natural history of superficial bladder carcinoma has an important bearing on the outcome of response to intravesical chemotherapy or immunotherapy. It may vary in different parts of the world, but it is essential that urologists know within their own practice how tumours respond to the initial transurethral resection. Many factors influence the natural history of superficial bladder carcinoma, and some, such as poor-grade, large tumour at presentation, smoking history, poor response to initial resection, and dysplasia or carcinoma in situ, should alert the urologist to introduce intravesical therapy at an early stage.

Transitional cell neoplasms of the urinary bladder. Can biologic potential be predicted from histologic grading?

The concept that most transitional cell neoplasms of the urinary bladder exist as either nonaggressive lesions of low cytologic grade or aggressive anaplastic cancers is gradually gaining acceptance. The extent to which the biological potential of these neoplasms is revealed in their pathologic features is the subject of this article. Using guidelines developed in experimental models, a series of 400 transitional cell neoplasms selected for long-term follow-up were classified into the WHO system. The results indicate that (1) almost all transitional cell tumors can be grouped into low and high grades at initial presentation; (2) the low grade lesions (usually designated transitional cell carcinoma, Grade I) are benign and should be called papillomas rather than carcinomas; (3) the risk of progression is not a function of the number of recurrences for these noninvasive, low-grade, papillary tumors; (4) the high-grade neoplasms are aggressive whether papillary or nodular and account for greater than 93% of tumor-related deaths; (5) patients with high-grade lesions have a reduced life expectancy even if progression does not occur; (6) depth of invasion and growth pattern are limited as predictive factors compared with histologic grade; (7) histologic grading of the initial tumor tissue can be highly predictive of outcome.

Theoretical mechanisms for synthesis of carcinogen-induced embryonic proteins: XVII. Heterochromatin mechanisms

A mechanism for induced embryonic gene expression via a process of deheterochromatization using a model carcinogen has been derived. First ethionine becomes activated to S-adenosyl-L-ethionine which inhibits the methylation of nicotinamide, a resulting product of polyADP-ribose polymerase. This causes hyporibosylated nucleosome core histones which normally would base pair by virtue of the adenine moieties with thymidine-rich regions of DNA, being the precursor of heterochromatin. Thus in the anomalous state a deheterochromatized condition of embryonic genes would be created. Possibly embryonic genes are dispersed in AT-rich regions potentially capable of becoming hyperspiralized by this process. Repressable embryonic genes would not be inactivated. It was also noted that hyomethylated non-histone chromatin proteins cause an extension of the nucleosome chanins which would also favor the above situation. This mechanism explains our experimental findings of the relatively rapid reversal of ethionine induced alpha-fetoprotein levels by methionine. The process of heterochromatization is hypothesized to be induced by short (pentanucleotides) moities of poly (ADP-ribose), formed on core histones, that hydrogen bond to thymidine rich inter Nu body DNA.

Transitional cell carcinomas of the urinary bladder. Effects of preoperative irradiation on morphology

The effects of preoperative irradiation on the morphology of transitional cell carcinomas (TCCs) were evaluated by studying the pretreatment biopsy and radical cystectomy specimens from 35 patients. Twenty-six of these patients had received 2000 rad within the week preceding surgery, and nine patients had received no preoperative treatment. The frequency of bladders without residual TCC was 23% for irradiated and 22% for nonirradiated cases. Of the TCCs classified as papillary in the biopsy specimens and irradiated, 79% lacked a papillary component at cystectomy, but in no case was the invasive component eliminated or regression from muscle invasion to superficial TCC noticed. Flat carcinoma in situ (CIS) did not respond to irradiation. At cystectomy nuclear pleomorphism was greater than at biopsy in 60% of the irradiated TCCs, whereas all nonirradiated cases retained the same grade as at biopsy. In addition, irradiation induced squamous differentiation in neoplastic cells only, without affecting the nonneoplastic urothelium.

Carcinogenesis in mammalian urothelium: changes induced by non-carcinogenic substances and chronic indwelling catheters

Carcinogenesis in urinary bladders may not be represented by a continuum of pathological lesions beginning with papillary tumors or flat dysplasias/atypias. In a previous experiment, sterile water and saline continuously infused via catheters connected to ALZA mini-pumps were shown to induce papillary urothelial lesions indistinguishable from tumors considered to be carcinomas in most histological classification schemes. The animals in the initial experiment were followed for relatively brief periods which did not allow for determination of potential reversibility of the process and did not distinguish the effects of the catheters versus those of the infused substances. The present study was designed to control for these variables. Rats were divided into seven groups to examine the urothelial changes after: surgery alone, continuous infusion of the sterile water and mitomycin C, and chronic indwelling catheters with and without infusion. The results indicated that chronic irritation with indwelling catheters was a strong stimulus for the induction of urothelial neoplasms and that continuous infusion of certain substances, even sterile water, might play a small role in the process of carcinogenesis. Comparing the frequencies of papillary urothelial tumors appearing after brief exposure to sterile water and catheters in the initial experiment (75 per cent) and papillary lesions appearing long after removal of the sterile water and catheters in the current study (0 per cent) indicates that these lesions are reversible and probably not neoplastic.

Urothelial dysplasia and carcinoma in situ of the bladder

Urothelial cells were pepsin-extracted from paraffin-embedded specimens taken from human nontumorous bladder mucosa, dysplasia, and carcinoma in situ. After Feulgen staining for DNA, nuclei were measured with an integrating microdensitometer. The measurements show that normal urothelium consists mostly of diploid nuclei. Dysplasia means that there is a predominance of tetraploid DNA values, whereas carcinoma in situ is characterized by a high percentage of aneuploid cells. In both dysplasia and carcinoma in situ there is a considerable percentage of diploid nuclei. Thus, DNA cytophotometry can be used for standardization of preneoplastic and early stages of tumor development in bladder cancer.

Morphologic changes in rat urothelial cells during carcinogenesis: I. Histologic and cytologic changes

The methods of either image or flow cytometry applied to developing bladder tumors in rats requires satisfactory cell samples and a system for cell classification that is related to the lesions from which the cells are derived. Seven- to eight-week-old male Fisher 344 rats were fed 0.05% of the carcinogen N-butyl-4-N-hydroxybutylnitrosamine (BBN) in drinking water for 10 wk and then returned to tap water. Animals were killed at 14, 26, 34, 45 and 62 wk after the start of carcinogen feeding. Age-matched untreated animals were controls. Bladders were fixed, embedded, sectioned, and histologically evaluated, or were dissociated with a trypsin/EDTA solution into single cells that were Papanicolaou stained and evaluated for cytopathologic changes. Overnight urines were collected before killing; urine sediments were Papanicolaou stained and evaluated. Histologic features were hyperplasia at 14 wk, followed by slowly progressing papillary transitional cell tumors that eventually led to invasive carcinoma and were similar to those reported for this animal model. Treated animals had cytologic features of repair at 14 and 26 wk and neoplastic features at 45 and 62 wk. Both reparative and neoplastic changes were found at 34 wk. Cells were much more numerous in urines from treated rats (greater than 1,000 per sample) than in urines from controls (less than 1,000 per sample). Although exfoliated cells in urine samples were generally of poor quality, as many as 11% of cells were adequately preserved.(ABSTRACT TRUNCATED AT 250 WORDS)

Urinary cytology and bladder cancer. The cellular features of transitional cell neoplasms

Urinary cytology is increasingly accepted as a diagnostic tool in the detection and follow-up of patients with bladder cancer. Its potential value has been reduced, however, by the relative inexperience of most pathologists in the examination of urinary specimens, and by the lack of cellular criteria specifically reflecting the morphology of low-grade papillary and flat lesions of bladder epithelium. The cytologic features of urothelial lesions, including papillary transitional cell carcinomas and flat urothelial dysplasias have been studied in both experimental systems and clinical situations and their application to a selected patient population is presented. Overall, the cytohistologic correlation for patients with bladder cancer was 92%. Positive cells reflecting the morphology of the tumor occurred in 62% of patients with grade I transitional cell carcinomas, and cells suspicious for malignancy were identified in an additional 14% of these individuals. Using the criteria presented, a positive cytology can correlate with a papillary grade I bladder tumor, and should not necessarily indicate the presence of another neoplasm. Dysplastic cells in cytologic specimens are often identified in patients having urothelial dysplasia as the most serious bladder lesion, but the cytologic diagnosis of dysplasia may represent an under-interpretation of a low-grade papillary bladder tumor. The cells of urothelial neoplasms, including low-grade transitional cell carcinomas and dysplasias, differ morphologically both from normal and reactive/reparative elements, and can be detected in cytologic samples. The changes are often subtle and require experience and a cautious approach for accurate interpretation.