EXPERIMENTAL STUDIES ON THE BIOLOGICAL POTENTIAL OF BLADDER TUMORS

Cell proliferation of human bladder tumors determined by BrdUrd and Ki-67 immunostaining

The cell proliferation of bladder tumors was assessed in situ using BrdUrd (bromodeoxyuridine) and Ki-67 immunostaining. BrdUrd is incorporated into S-phase cells, and Ki-67 monoclonal antibody recognizes a nuclear antigen present in proliferating, but not resting cells. The percentage of labeled cells was expressed as the labeling index (LI). The average BrdUrd LI obtained applying this method to normal epithelium and to transitional cell carcinoma were 4.1% and 13.1%, respectively, while the Ki-67 LI had average values of 6.2% and 17.8%, respectively. Labeled cells were distributed throughout both the basal and surface layers of transitional cell carcinoma. In general, the value of the BrdUrd LI was correlated to that of the Ki-67 LI. A relatively large fraction of labeled cells was found in high grade or invasive tumors. Bladder tumors with lymph node involvement had higher LI than those without. In addition, a high frequency of S-phase cells within tumor tissue appeared to indicate a great potential for malignancy and thus a poor prognosis. These findings indicate that immunostaining with BrdUrd and Ki-67 may be useful tools for easy and quick evaluation of proliferating cells in bladder tumors.

The kinetics of cellular proliferation in rat urinary bladder treated with N-butyl-N-(4-hydroxybutyl)nitrosamine

The cellular proliferation of the bladder epithelium was determined sequentially in rats treated with N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN). The incorporation of bromodeoxyuridine (BrdUrd) into the DNA synthesis phase was determined by an in vitro labeling technique. The percentage of labeled cells was expressed as the labeling index (LI). The average LI values in normal subjects and cancer-bearing subjects were 5.1(%) and 24.2(%) respectively. With the transition of the bladder epithelium from simple hyperplasia to cancer, the LI values of the bladder epithelium were increased. Cases of papillary or nodular (PN) hyperplasia were divided into two types according to the localization of the BrdUrd-labeled cells. The LI in PN hyperplasia was 12.4(%); the difference from cancer was significant. In another experiment, the effect of partial cystectomy on bladder tumors was examined. The group with partial cystectomy showed increases in grade and stage of cancer, and the LI of cancer was more than that in the group without partial cystectomy. The results indicate that partial cystectomy may play a role as promotor for bladder tumors. The current study may be of more practical value than is the conventional one for investigating the histogenesis and progression of human bladder cancer.

Cell proliferation of human bladder tumors

The cell proliferation of bladder tumors was assessed via an immunohistochemical technique using anti-bromodeoxyuridine (BrdUrd) antibody. The incorporation of the thymidine analogue, BrdUrd, into DNA synthesis phase was performed by an in vitro labeling technique. The percentage of labeled S-phase cells was expressed as the labeling index (LI). Discrimination between BrdUrd-labeled and unlabeled cells was easy because of the absence of background staining. The average LI obtained using this method in normal, normal epithelium bearing bladder tumors and cystitis was 5.0%, 4.0% and 5.0%, respectively. On the other hand, LI in bladder tumors was 13.0%, while the difference from non-malignant bladder epithelium was significant. As in high grade tumors, the labeled cells distributed throughout both the basal and surface layers of epithelium, compared to low grade tumors and controls. However, there was some variation in the distribution pattern within the same tumor depending on the histological site. On the other hand, the higher S-phase fraction was found in high grade or invasive bladder tumors. Bladder tumors with lymph node involvement had higher LI than those without the involvement. In patients who underwent TUR, the LI was as high as 10.0% in the recurrent group compared with 7.3% in the non-recurrent group. Moreover, in the total cystourethrectomy group, higher LI's were obtained in a patient dying of cancer (20.0%) and a patient with postoperative metastasis (21.0%) than in the non-recurrent group (14.8%). The high frequency of S-phase cells within tumor tissue appears to indicate a more malignant potential and thus a poor prognosis. Although further studies are required for its full significance, the measurement of BrdUrd labeling index by in vitro labeling method promises to afford useful information regarding the biological behavior of bladder tumors.

Correlation between in vitro autoradiographic results and histological WHO grades in human urothelial bladder tumours

253 biopsy specimens of 106 urinary bladder tumours have been examined by means of in vitro autoradiography and the results compared with the WHO grading. An increase of the average labelling index occurred parallel to increasing WHO grades. However, great inter-tumorous differences in proliferation behaviour existed particularly in papillary G2 and G3 urothelium carcinomas. Possible causes of this heterogeneity are discussed. In vitro autoradiography is a suitable method for the objective characterization of the malignancy potential of urinary bladder tumours.

Mapping of cell cycle distribution in normal human urinary bladder epithelium

A method is described by which urothelial cells from well defined areas in the urinary bladder mucosa can be obtained. At cystoscopy epithelial cells are aspirated by means of a ureteral catheter. The cells obtained by this selective sampling technique are well suited for morphology and for quantitative single cell measurements by flow cytometry (FCM). In the present study the cell cycle distribution has been measured by FCM. Twenty-five patients (13 males and 12 females) had urothelial cells collected from well defined areas in the mucosa and the DNA content measured from different sites separately. The distribution of bladder mucosa cells in the different parts of the cell cycle (G1, S-phase and G2 + M) is reported. No significant differences were found with regard to sex and age of the patients. Also, a low regional variation was found in the bladder mucosa indicating that the method should enable the discrimination of even small abnormal cell populations in tumour disease. No evidence of polyploidy in the human urothelium was found.

Cell-cycle distribution of urothelial tumour cells as measured by flow cytometry

The fraction of cells in S + G2 + mitosis from 54 urothelial tumours was calculated by flow cytometry after acridine orange (AO) staining of cells obtained by bladder irrigation or biopsy. Fluorescence signals emitted by the AO-stained DNA and RNA of each cell were separated optically and measured for 5,000 cells per specimen. The patients were classified by the histology of their tumours and clinical data into 5 diagnostic categories: NED (no evidence of disease, but history of bladder tumour), 3; papilloma, 8; non-invasive papillary carcinoma, 8; carcinoma in situ, 17 and invasive carcinoma, 18. The fraction of cells with DNA values in S + G2 + M of the cell cycle varied between 7 and 57% of the total, with a wide range within each diagnostic category, but no statistically significant differences between the groups. The proportion of cells in S + G2 + M from an individual tumour was not correlated with histologic grade or clinical behaviour. The possibility that some tumour cells with DNA values above G1 level are quiescent cells arrested at S or G2 is discussed.

Topical instillation of doxorubicin hydrochloride in the treatment of recurring superficial transitional cell carcinoma of the bladder

Thirteen patients with recurring stage A transitional cell carcinoma of the bladder were treated with monthly bladder instillations of doxorubicin hydrochloride. Follow-up at 3-month intervals has shown excellent control of tumor recurrence with complete remissions for up to 21 months in 2 patients. The median for remission in 8 of 13 patients has been 10 months. Two patients with bladder papillomatosis were treated successfully by the same method.

Prophylaxis of bladder tumor implantation. Intravesical and systemic chemotherapy

Several antitumor agents have been evaluated for their effectiveness in reducing the implantation and progressive growth of transitional cell carcinoma in an animal model. This system allows the evaluation of both the topical cytotoxic action as well as the systemic toxicity of the drugs given intravesically. Systemic cyclophosphamide and intravesical epipodophyllotoxin significantly reduced the incidence of tumor cell implantation.

Stages of transformation in the development of N-butyl-N-(4-hydroxybutyl)-nitrosamine-induced transitional cell carcinomas in the urinary bladder of rats

The histogenesis of papillary and nonpapillary transitional cell carcinomas were studied morphologically and autoradiographically in 177 female Wistar rats after oral application of N-butyl-N-(4-hydroxybutyl)-nitrosamine with varying exposure and induction times. By far the largest proportion of carcinomas developed by a malignant transformation of preexisting papillomas or their precursors, the papillary hyperplasias. The transition into a focally malignant growth did not take place abruptly, but occurred stepwise through different successive stages of transformation, each having its own distinct morphological character. The first stage consisted of a focal, sharpely defined cellular atypia. In a further stage carcinomata in situ developed out of the atypical foci and progressed finally in a last stage of transformation into a circumscript infiltrative growth. The successive development of each stage occurred independent of any further carcinogen application after transformation was initiated at the molecular level. The number of papillomas with transformation stages increased with a lengthening of the exposure and induction time. 74.4% of all the registered papillomas had been transformed. Consequently papillomas must be considered potentially highly malignant. The 3H-TdR index was 4.2 times higher in atypical urothelial areas (7.6%) and 7.5 times higher in carcinomata in situ (14.3%) than in the surrounding papillomatous structures which appeared light microscopically benign. The latter demonstrated a rather constant 3H-TdR index, whether they bordered on atypical foci (1.8%) or carcinomata in situ (1.9%). The length of exposure and induction time exercised no significant influence on the degree of proliferative activity. The development of transitional cell carcinomas from a primary carcinoma in situ (intraurothelial carcinoma) played a much less significant role.