The expression of the human Ki-67 protein is strictly associated with cell proliferation. During interphase, the antigen can be exclusively detected within the nucleus, whereas in mitosis most of the protein is relocated to the surface of the chromosomes. The fact that the Ki-67 protein is present during all active phases of the cell cycle (G(1), S, G(2), and mitosis), but is absent from resting cells (G(0)), makes it an excellent marker for determining the so-called growth fraction of a given cell population. In the first part of this study, the term proliferation marker is discussed and examples of the applications of anti-Ki-67 protein antibodies in diagnostics of human tumors are given. The fraction of Ki-67-positive tumor cells (the Ki-67 labeling index) is often correlated with the clinical course of the disease. The best-studied examples in this context are carcinomas of the prostate and the breast. For these types of tumors, the prognostic value for survival and tumor recurrence has repeatedly been proven in uni- and multivariate analysis. The preparation of new monoclonal antibodies that react with the Ki-67 equivalent protein from rodents now extends the use of the Ki-67 protein as a proliferation marker to laboratory animals that are routinely used in basic research. The second part of this review focuses on the biology of the Ki-67 protein. Our current knowledge of the Ki-67 gene and protein structure, mRNA splicing, expression, and cellular localization during the cell-division cycle is summarized and discussed. Although the Ki-67 protein is well characterized on the molecular level and extensively used as a proliferation marker, the functional significance still remains unclear. There are indications, however, that Ki-67 protein expression is an absolute requirement for progression through the cell-division cycle.

The Ki‐67 protein: From the known and the unknown

Pathology and genetics of tumours of the urinary system and male genital organs

BACKGROUND AND AIMS Controversy surrounds the risk of colorectal cancer (CRC) in ulcerative colitis (UC). Many studies have investigated this risk and reported widely varying rates. METHODS A literature search using Medline with the explosion of references identified 194 studies. Of these, 116 met our inclusion criteria from which the number of patients and cancers detected could be extracted. Overall pooled estimates, with 95% confidence intervals (CI), of cancer prevalence and incidence were obtained using a random effects model on either the log odds or log incidence scale, as appropriate. RESULTS The overall prevalence of CRC in any UC patient, based on 116 studies, was estimated to be 3.7% (95% CI 3.2–4.2%). Of the 116 studies, 41 reported colitis duration. From these the overall incidence rate was 3/1000 person years duration (pyd), (95% CI 2/1000 to 4/1000). The overall incidence rate for any child was 6/1000 pyd (95% CI 3/1000 to 13/1000). Of the 41 studies, 19 reported results stratified into 10 year intervals of disease duration. For the first 10 years the incidence rate was 2/1000 pyd (95% CI 1/1000 to 2/1000), for the second decade the incidence rate was estimated to be 7/1000 pyd (95% CI 4/1000 to 12/1000), and in the third decade the incidence rate was 12/1000 pyd (95% CI 7/1000 to 19/1000). These incidence rates corresponded to cumulative probabilities of 2% by 10 years, 8% by 20 years, and 18% by 30 years. The worldwide cancer incidence rates varied geographically, being 5/1000 pyd in the USA, 4/1000 pyd in the UK, and 2/1000 pyd in Scandinavia and other countries. Over time the cancer risk has increased since 1955 but this finding was not significant (p=0.8). CONCLUSIONS Using new meta-analysis techniques we determined the risk of CRC in UC by decade of disease and defined the risk in pancolitics and children. We found a non-significant increase in risk over time and estimated how risk varies with geography.

https://gut.bmj.com/content/gutjnl/48/4/526.full.pdf

The risk of colorectal cancer in ulcerative colitis: a meta-analysis

Neoplasms are microcosms of evolution. Within a neoplasm, a mosaic of mutant cells compete for space and resources, evade predation by the immune system and can even cooperate to disperse and colonize new organs. The evolution of neoplastic cells explains both why we get cancer and why it has been so difficult to cure. The tools of evolutionary biology and ecology are providing new insights into neoplastic progression and the clinical control of cancer.

Cancer as an evolutionary and ecological process.

The athymic (nude) mouse is a useful model for studying the biology and response to therapies of human tumors in vivo. A survey of recent literature revealed the use of 19 different formulas for determining the size of subcutaneous tumors grown as xenografts in nude mice (2 for determining tumor area, 3 for tumor diameter, and 14 for calculating tumor volume). We compared the volumes, areas, and diameters predicted by each of the 19 formulas with the actual weights of 50 tumors ranging from 0.46 to 22.0 g established in nude mice as xenografts from human cell lines. In addition to determining how well each formula predicted relative tumor size, we analyzed how well each formula estimated actual tumor mass. The ellipsoid volume formulas (π/6 x L x W x H and 1/2 x L x W x H) were best for estimating tumor mass (r=0.93), whereas measurements of diameter correlated poorly with tumor mass (r<0.66). Although determination of tumor area correlated well with tumor mass in small tumors (r=0.89), correlations of area with tumor mass for large tumors were poor (r=0.41). We conclude that determination of the ellipsoid volume from measurements of three axes consistently yields the most accurate estimations of both relative and actual tumor mass.

Determination of subcutaneous tumor size in athymic (nude) mice

A DNA Cytometry Consensus Conference was con- ducted to examine clinical applications and technical aspects of DNA ploidy analysis in patients with tran- sitional cell carcinoma of the bladder. Participant se- lection was based on expertise and published results presenting clinical follow-up. Consensus conclusions, positive or negative, were established by a critical re- view of representative publications. Some publications were excluded from review be- cause data were insufficient to permit comparative analysis.

Consensus review of the clinical utility of DNA cytometry in bladder cancer

The cellular DNA content of 81 soft tissue tumors was determined by means of flow cytometry and related to conventional histologic classification of the same tumors. Comparison of histologic and cytometric analysis showed that all 23 benign tumors were diploid (normal DNA content), whereas the malignant group included both diploid and aneuploid (abnormal DNA content) lesions. There appeared to be a relationship between tumor grade and ploidy level in that 92% of Grade II, 28% of Grade III, and 11% of Grade IV lesions were diploid. Cell distribution analysis, feasible in 51 cases, disclosed that diploid lesions had a low proportion of S and G2 + M cells and most aneuploid lesions a high proportion, indicating a relationship between ploidy level and proliferative activity. The current study shows that solid mesenchymal tumors may be analyzed by DNA flow cytometry. Regardless of histogenetic type, it appears that benign and low-grade tumors are diploid and high-grade tumors, in general, are aneuploid. As to exceptions, DNA analysis may prove to give information beyond that obtained by subjective histologic interpretation. Thus, adequate follow-up might show that high-grade lesions with a diploid DNA content are associated with a better prognosis than expected from histologic classification.

DNA flow analysis of soft tissue tumors

DNA aneuploidy in ulcerative colitis: Reproducibility, topographic distribution, and relation to dysplasia

A modification of the Hedley-method for flow cytometric DNA analysis of paraffin-embedded tissues is presented. Dewaxed and dehydrated tissue from paraffin blocks was incubated with subtilisin Carlsberg (pronase, Sigma protease XXIV) and then stained directly without washing and centrifugation. The loss of material was minimized, which was advantageous, for example, for the analysis of core-biopsies, and all measured samples showed extremely low frequencies of clumped cell nuclei. This made is easier to detect polyploid nuclei and even rare nuclei of high ploidy could be identified. S-phase analyses were more precise, since the background originating from clumped debris particles was very low. The improved method was applied to the estimation of frequencies of high-polyploid nuclei found in various diploid, tetraploid, and aneuploid human myosarcomas of the uterus.

An improved Hedley method for preparation of paraffin-embedded tissues for flow cytometric analysis of ploidy and S-phase.

The cellular DNA pattern in 66 colo-rectal adenocarcinomas was studied by means of flow-cytometric DNA analysis. The degree of ploidy and the proportion of cells in S-phase were related to the clinical stage according to Dukes' classification and to the histological differentiation. Multiple cell populations were found in about 60 per cent of the tumours but more frequently in advanced clinical stages. According to the DNA index the cell populations were bimodally distributed with one peak in the diploid-peridiploid region and one peak in the tri- to tetraploid region. In the second group there was a higher frequency of more advanced tumours as compared to the first. The proportion of cells in S-phase was higher in pure diploid tumour cell populations of all clinical stages as compared to normal mucosa but lower as compared to peridiploid and aneuploid cell populations with high DNA index. High as well as low S-phase values may occur in all clinical stages, but a significant higher mean value was found for Dukes' C compared to Dukes' B tumours. Distant metastases occur at all DNA indices and with various S-phase values. In conclusion, tumours of different clinical stages and histological differentiation may be subdivided according to DNA index, to the existence of single or multiple cell populations and to the proportion of cells in S-phase. The biological significance of this subdivision can only be evaluated by means of clinical follow-up.

Ploidy and proliferation patterns in colo-rectal adenocarcinomas related to Dukes' classification and to histopathological differentiation. A flow-cytometric DNA study.

Bernhard Tribukait

Papers

Consensus review of the clinical utility of DNA cytometry in bladder cancer

DNA flow analysis of soft tissue tumors

DNA aneuploidy in ulcerative colitis: Reproducibility, topographic distribution, and relation to dysplasia

An improved Hedley method for preparation of paraffin-embedded tissues for flow cytometric analysis of ploidy and S-phase.

Ploidy and proliferation patterns in colo-rectal adenocarcinomas related to Dukes' classification and to histopathological differentiation. A flow-cytometric DNA study.