Role of Proliferative Activity Estimated by Bromodeoxyuridine Labeling Index in Determining Predictive Factors of Recurrence in Superficial Intermediately Malignant Bladder Tumors

Use of the comet-FISH assay to compare DNA damage and repair in p53 and hTERT genes following ionizing radiation

The alkaline single cell gel electrophoresis (comet) assay can be combined with fluorescent in situ hybridisation (FISH) methodology in order to investigate the localisation of specific gene domains within an individual cell. The number and position of the fluorescent signal(s) provides information about the relative damage and subsequent repair that is occurring in the targeted gene domain(s). In this study, we have optimised the comet-FISH assay to detect and compare DNA damage and repair in the p53 and hTERT gene regions of bladder cancer cell-lines RT4 and RT112, normal fibroblasts and Cockayne Syndrome (CS) fibroblasts following γ-radiation. Cells were exposed to 5Gy γ-radiation and repair followed for up to 60 minutes. At each repair time-point, the number and location of p53 and hTERT hybridisation spots was recorded in addition to standard comet measurements. In bladder cancer cell-lines and normal fibroblasts, the p53 gene region was found to be rapidly repaired relative to the hTERT gene region and the overall genome, a phenomenon that appeared to be independent of hTERT transcriptional activity. However, in the CS fibroblasts, which are defective in transcription coupled repair (TCR), this rapid repair of the p53 gene region was not observed when compared to both the hTERT gene region and the overall genome, proving the assay can detect variations in DNA repair in the same gene. In conclusion, we propose that the comet-FISH assay is a sensitive and rapid method for detecting differences in DNA damage and repair between different gene regions in individual cells in response to radiation. We suggest this increases its potential for measuring radiosensitivity in cells and may therefore have value in a clinical setting.

DNA ploidy, proliferative capacity and intratumoral heterogeneity in primary and recurrent head and neck squamous cell carcinomas (HNSCC) – Potential implications for clinical management and treatment decisions

Despite new diagnostic and therapeutic strategies (combined radiochemotherapy, EGFR antibody Cetuximab), the prognosis of head and neck squamous cell carcinoma (HNSCC) is still poor and more information regarding prognosis is essential to establish earlier and better treatment options. To elucidate the role of DNA ploidy and cellular proliferation, resected tumors of 48 patients with primary or recurrent HNSCC were analyzed by flow cytometry and in vitro-5-bromodeoxyuridine incorporation (BrdU). The results were compared with histopathological findings such as tumor size, lymph node involvement and tumor differentiation. To assess the influence of intratumoral heterogeneity of these biological parameters, multiple biopsies (>3) were analyzed by flow cytometry and BrdU-incorporation in 12 larger (>4 cm diameter) tumors. BrdU-labeling index (LI%) was significantly higher in aneuploid HNSCC and correlated significantly with poor histologic differentiation of the analyzed tumor tissues (P<0.001). Furthermore, a trend for higher LI% in nodal positive tumors was observed. Aneuploid HNSCC showed significantly more often tissue dedifferentiation (P=0.049) and in most cases an advanced tumor stage, especially in tumors with biclonal cell lines. Lymph node involvement was also seen more often in aneuploid and undifferentiated tumors. As in aneuploid tumors recurrent HNSCC showed in most cases a higher LI% and poor tissue differentiation, but as a result of the small collection of samples there was no correlation between aneuploidy and tumor recurrence. To proof the robustness of the acquired data and to estimate the influence of intratumoral heterogeneity to ploidy and LI% multiple biopsies were analyzed in larger tumors. Using a specific statistical algorithm a secure estimation of ploidy and LI% was possible by a single biopsy in these tumors. These findings indicate aneuploidy and proliferative activity as important findings for malignant progression in HNSCC. An estimation of these biological parameters may be useful for identification of patients with high risk for lymph node involvement or tumor recurrence and pre-treatment can be performed by a single biopsy. As a conclusion, these patients may benefit from more aggressive treatment.

Cell production rates in human tissues and tumours and their significance. Part II: clinical data

This paper reviews the available data for cell production rates of human tissues and tumours, measured in vivo using halogenated pyrimidine labelling and laser cytometry. The technique has now been widely evaluated, and we draw general inferences from the proliferative data over a broad range of tumour and tissue types. Estimates of the S-phase duration, the time taken for DNA synthesis in cycling cells, are consistent over a narrow range with a median value of around 10 hours, notwithstanding the constraints of the experimental and statistical technique, in normal tissues and tumours. This suggests that Ts values may be a species-specific constant. The more easily measured labelled S-phase fraction, or labelling index, shows much greater intra and intertumour variation within any one tumour class. It may thus be a surrogate for time dependent measurements to a first order approximation. The cell production rate, described by the potential doubling time (Tpot), is remarkably rapid in most tumours, a median value of the order of 5 days, and much faster than clinical volume doubling times for most lesions. The rapid cell production rates in normal tissues and tumours highlight the importance of cell loss in the growth and modelling of biological structures. Cell production rate measurements do not adequately describe the biological aggressiveness of tumours. They may be used to refine adjuvant strategies for radiotherapy and chemotherapy in experimental research. Dynamic halogenated pyrimidine labelling has provided unique and valuable insights into the living biology of human tissues and tumours.

Cell production rates in human tissues and tumours and their significance. Part 1: an introduction to the techniques of measurement and their limitations

In the past two decades, the technology of laser cytometry and use of the halogenated thymidine (HP) analogues bromodeoxyuridine and iododeoxyuridine as proliferation labels, have allowed us to quantify the rate of cell turnover in tissues and tumours, in clinical samples as in laboratory models. The principal studies have used injection of bromo- or iododeoxyuridine to measure cell production rates in vivo. Flow cytometry (FCM) has been used to estimate the S phase labelling index (LI) and the S phase duration (Ts) and calculate the cell production rate, represented by the potential doubling time (Tpot). This has allowed calculation of time-dependent indices of proliferation from single biopsies of HP pulse labelled human tissues and tumours. In the first part of this two-part review, we describe the technique and its limitations as a biological assay. The second part summarizes the knowledge gained about cell production rates and the relevance that this information may have to future investigative, prognostic and treatment strategies.

Bladder tumor markers: need, nature and application. 1. Nucleus-based markers

Urothelial tumors are common: their diagnosis and long-term management represent a large part of most urologists' workload. The majority of such tumors are 'superficial' and are mostly managed by repeated cystoscopic surveillance and treatment. A smaller but significant group of patients either start with, or subsequently progress to, more invasive disease, thus requiring an alternative and more invasive treatment. Maximizing the benefit/risk ratio of the diagnosis and the various treatment options of bladder tumors requires the availability of a reliable tumor marker. The concept of tumor markers encompasses the utilization of any detectable deviation from normality that is indicative of neoplasia. For bladder cancer, most of these markers are present in urine. In this part of the review we examine, from the clinician's point of view, the literature verdict on older techniques such as cytology and cytometry, as well as the current status of new nucleus-based tests such as P53, telomerase, NMP22 and Ki67.

Association between in vivo iododeoxyuridine labeling, MIB-1 expression, malignancy grade and clinical stage in human prostate cancer

Large variability in the biological behavior of prostate cancer makes prognostic markers important. The extent of tumor cell proliferation has been suggested as an important predictor of clinical outcome. Fifty-five patients suspected of having or with previously diagnosed prostate cancer were labeled in vivo with IdUrd (a thymidine analogue incorporated into DNA in S-phase cells) by intravenous infusion before transurethral resection. IdUrd-labeled cells and MIB-1-positive cells were detected by immunohistochemistry. We found statistically significant associations between the tumor cell proliferation rates measured by in vivo IdUrd labeling and MIB-1 expression in formalin-fixed paraffin-embedded tumors. Good correlations were also found between S-phase fraction, MIB-1 expression, clinical stage and malignancy grade. These results make larger retrospective studies on archival tissue meaningful.