Nuclear morphometry for improved prediction of the prognosis of human bladder carcinoma

Morphometric Analysis of Suprabasal Cell Layer in Oral Epithelial Dysplasia: A Computer-assisted Microscopic Study

Background:

Oral leukoplakia is the most common precancerous lesion. Various grading systems based on histological findings have been proposed for dysplasia. Recently, computer-assisted morphometric analysis has been established to reduce the interobserver and intraobserver variability during the histological grading of epithelial dysplasia. This study was undertaken to establish the morphometric changes in the suprabasal cell layer of different grades of oral epithelial dysplasia.

Materials and Methods:

Forty paraffin-embedded tissue sections (10 normal mucosa, 10 mild dysplasia, 10 moderate dysplasia, and 10 severe dysplasia cases) were stained using hematoxylin and eosin stain, and analyzed for cellular and nuclear morphometry using binocular microscope.

Results:

Our results showed that values of nuclear area, nuclear perimeter, nuclear volume density, and nuclear/cytoplasmic (N/C) ratio were increased gradually in dysplasia compared to control groups and the values were statistically significant (P = 0.001). Nuclear diameter and cellular area were increased in dysplasia when compared to control group (P = 0.001). Mild and moderate dysplasia showed decreased value of nuclear form factor compared to control group, whereas severe dysplasia showed highest value. A fair correlation was found when comparing histological grading and grouping based on nuclear area, nuclear perimeter, N/C ratio, and nuclear volume density.

Conclusion:

Nuclear features reflect cell behavior, and its morphometric analysis can be considered as a reliable tool for differentiating various grades of epithelial dysplasia.

Nuclear features in different grades of epithelial dysplasia in leukoplakia: A computer assisted microscopic study

Context:

Abnormalities in nuclear morphology are very frequently seen in dysplasia, such as nuclear area, diameter, shape, number of nucleoli and membrane outline. The purpose of this study was to observe and compare the nuclear features in different grades of epithelial dysplasia in leukoplakia and to evaluate the use of Feulgen stain for observing the nuclear features in oral epithelial dysplasia in leukoplakia. Seventy paraffin embedded tissue section (20 mild, 20 moderate, 20 severe dysplasia cases and 10 control specimens) were analyzed for nuclear morphology using Feulgen stain under trinocular research microscope. Statistically significant results were obtained with P > 0.001, when intergroup comparison was done except in case of nuclear area and diameter between mild and moderate dysplasia. Nuclear features reflect cell's biological potential and its morphometry was found to be a useful tool for differentiating different grades of dysplasia.

NETs and cell cycle regulation

There are many ways that the nuclear envelope can influence the cell cycle. In addition to roles of lamins in regulating the master cell cycle regulator pRb and nuclear envelope breakdown in mitosis, many other nuclear envelope proteins influence the cell cycle through regulatory or structural functions. Of particular note among these are the nuclear envelope transmembrane proteins (NETs) that appear to influence cell cycle regulation through multiple separate mechanisms. Some NETs and other nuclear envelope proteins accumulate on the mitotic spindle, suggesting functional or structural roles in the cell cycle. In interphase exogenous overexpression of some NETs promotes an increase in G1 populations, while others promote an increase in G2/M populations, sometimes associated with the induction of senescence. Intriguingly, most of the NETs linked to the cell cycle are highly restricted in their tissue expression; thus, their misregulation in cancer could contribute to the many tissue-specific types of cancer.

The nuclear envelope and cancer: a diagnostic perspective and historical overview

Cancer has been diagnosed for millennia, but its cellular nature only began to be understood in the mid-nineteenth century when advances in microscopy allowed detailed specimen observations. It was soon noted that cancer cells often possessed nuclei that were altered in size and/or shape. This became an important criterion for cancer diagnosis that continues to be used today. The mechanisms linking nuclear abnormalities and cancer only started to be understood in the second half of the twentieth century, with the discovery of nuclear lamina composition differences in cancer cells compared to normal cells. The nuclear envelope, rather than providing a mere physical barrier between the genetic material in the nucleus and the cytoplasm, is a very important functional hub for many cellular processes. In this review we give an overview of the links between cancer biology and nuclear envelope, from the early days of microscopy until the present day's understanding of some of the molecular mechanisms behind those links.

Cancer biology and the nuclear envelope: a convoluted relationship

Although its properties have long been used for both typing and prognosis of various tumors, the nuclear envelope (NE) itself and its potential roles in tumorigenesis are only beginning to be understood. Historically viewed as merely a protective barrier, the nuclear envelope is now linked to a wide range of functions. Nuclear membrane proteins connect the nucleus to the cytoskeleton on one side and to chromatin on the other. Several newly identified nuclear envelope functions associated with these connections intersect with cancer pathways. For example, the nuclear envelope could affect genome stability by tethering chromatin. Some nuclear envelope proteins affect cell cycle regulation by directly binding to the master regulator pRb, others by interacting with TGF-ß and Smad signaling cascades, and others by affecting the mitotic spindle. Finally, the NE directly affects cytoskeletal organization and can also influence cell migration in metastasis. In this review we discuss the link between the nuclear envelope and cellular defects that are common in cancer cells, and we show that NE proteins are often aberrantly expressed in tumors. The NE represents a potential reservoir of diagnostic and prognostic markers in cancer.

Nuclear roundness variance predicts prostate cancer progression, metastasis, and death: A prospective evaluation with up to 25 years of follow-up after radical prostatectomy

BACKGROUND

Nuclear structure is often altered in cancer due to spatial rearrangements of chromatin organization via activation of oncogenes and other chromatin remodeling genes. Therefore, we evaluated the prognostic value of nuclear roundness variance (NRV) for prostate cancer (PCa) progression, metastasis and PCa-specific death free survivals in a cohort of 116 men after radical prostatectomy (RP).

METHOD

NRV was calculated for each case using the variance of the nuclear roundness from approximately 150 nuclei captured at a magnification of 2,440x for each case in 1992-1993. $${\rm Nuclear}\,{\rm roundness} = {{{\rm Radius}({\rm circumference})} \over {{\rm radius}({\rm area})}} = {R \over r} = {{P/2\pi } \over {\sqrt {A/\pi } }}$$ NRV data were merged with clinical, pathologic, and follow-up data for all patients in 2009. Cox proportional hazards regression and Kaplan-Meier plots were employed to analyze the data.

RESULTS

Median follow-up time after RP for all patients was 19 years (range: 1-25 years, mean: 17 years), with approximately 92% (107/116), 71% (82/116), and 47% (55/116) patients having >or=10, 15, and 20 years of follow-up, respectively. NRV was the most significant parameter for prediction of all three outcomes and its concordance-index (C-Index) increased from progression (0.7080) to metastasis (0.7332) to PCa-specific death (0.8090) free survival predictions. Of note, NRV C-Index was significantly higher compared to Gleason Score C-Index for metastasis (0.7332 vs. 0.6046; P = 0.027) and PCa-specific death (0.8090 vs. 0.6336; P = 0.004) free survival predictions. However, the difference between NRV and Gleason Score C-Indexes was not statistically significant for progression free survival prediction (0.7080 vs. 0.6463; P = 0.106).

CONCLUSION

NRV is valuable nuclear structural feature that exceeds Gleason score to predict an aggressive phenotype of PCa.

Identification of bladder cancer patients at risk for recurrence or progression: an immunohistochemical study based on the expression of metallothionein

Despite similarities in tumor stage and grade the individual outcome of bladder cancer patients is not predictable. The ideal tool for treatment stratification has not yet been found. Metallothionein (MT) overexpression is correlated with poor tumor differentiation, resistance to chemotherapy, and impaired survival in different malignancies. The clinical relevance of MT expression for defining patients at high risk for recurrence or progression was assessed. MT was detected immunohistochemically and evaluated semiquantitively in tumor specimens of 103 male and 19 female patients (transsurethral resection: n = 94, cystectomy: n = 28). Mean age of the patients was 68 (38-87) yr. According to histopathological features, three groups were distinguished for further analysis (pTa-1G1-2, pTis/pT1G3, and muscle invasive tumors). A cutoff value of 50% immunoreactive cells was used for further analysis. The 5-yr tumor specific survival rate was significantly lower in patients with high MT expression (32 vs. 72%). Accordingly, impaired 5-yr recurrence (90 vs. 58%), and progression rates (78 vs. 54%) were associated with high MT expression. All patients suffering from pTis and pT1G3 tumors with MT expression above the cutoff value showed recurrence within less than 40 mo, whereas 26% of those patients with MT expression below the cutoff value remained long-term recurrence free. Long term progression free survival was detected in 75% of pT1G3 patients with MT expression below the cutoff value. In contrast, 68% of pT1G3 tumor patients with MT expression above the cutoff value progressed, all within the first 12 mo after initial tumor resection. A correlation between high MT expression and prognosis was demonstrated especially in pT1G3 and pTis tumors, where >50% MT expression was linked to shorter tumor-specific survival and increased recurrence/progression rates. Thus, MT expression seems to be a promising marker for further risk stratification in the clinical treatment of bladder cancer patients.

Comparison of DNA ploidy and nuclear morphometric parameters with the conventional prognostic factors in transitional cell carcinomas

Carcinomas of the bladder cause important problems of mortality and morbidity despite diagnostic and therapeutic improvements. A variety of grading systems has been developed to reflect the different biologic behavior and malignant potential of this heterogeneous neoplasm. However, these histologic grading systems are subjective and reproducibility is low. In this study, the nuclear morphometric features and DNA ploidy status of 86 cases of transitional cell bladder carcinomas have been studied using image analysis methods with different data selection methods in nucleus suspension to evaluate the relationship of these parameters with the conventional prognostic factors. The relationship between these parameters and likelihood of relapse has also been investigated. In conclusion, the mean nuclear area of the 10 largest nuclei and DNA ploidy status have been shown to be significantly correlated with conventional prognostic factors. Cytomorphometrically, a binary grading system seems more suitable for transitional cell carcinoma of the bladder. For superficial carcinomas, morphometric parameters and DNA ploidy analysis can be helpful in the separation of the patients into prognostically different groups.

An objective morphologic parameter to aid in the diagnosis of flat urothelial carcinoma in situ

The diagnosis of carcinoma in situ (CIS) lacks objective criteria and is subject to misdiagnosis. We identified 20 bladder biopsy cases each of CIS, urothelial dysplasia, and normal urothelium according to the 1998 World Health Organization/International Society of Urological Pathology consensus classification of urothelial neoplasms. Lymphocytes from 10 bladder biopsy specimens were chosen as reference cells. Using an image analysis system, we measured the following nuclear features: area, diameter, roundness, ellipticity, and optical density (maximum, minimum, mean, median, standard deviation, and quartiles). We measured a mean of 75 urothelial nuclei/case and a total of 500 lymphocytes. Roundness and ellipticity were not useful in distinguishing among the 3 groups. The best discriminators were mean nuclear area and mean nuclear area of the 25% largest nuclei (upper quartile) of urothelial cells compared with lymphocytes. The mean nuclear area relative to lymphocytes was 1.8 times (1.2 to 2.5 times) in normal urothelium, 2.4 times (1.6 to 3.0 times) in urothelial dysplasia, and 3.6 times (2.8 to 5.7 times) in CIS. The mean upper quartile nuclear area relative to lymphocytes was 2.2 times (1.4 to 2.8 times) in normal urothelium (P <.0001), 2.9 times (1.8 to 3.6 times) in urothelial dysplasia (P <.0001), and 4.9 times (4.0 to 7.6 times) in CIS (P <.0001). The difference in optical density was statistically significant between CIS and the other 2 histologic categories (P <.0001). Nuclear area is an easy and objective morphologic parameter for the evaluation of bladder biopsy specimens. Pathologists can assess the size of urothelial nuclei without using an image analysis system and compare them with the size of nuclei of lymphocytes, which are almost always present in a bladder biopsy specimen. Dysplasia, which is a somewhat ambiguous lesion, overlaps in its measurements with those of benign urothelium. The most useful morphologic parameter is the mean nuclear area of the 25% largest nuclei; CIS nuclei are approximately 5 times the size of lymphocytes, whereas normal urothelial nuclei are only 2 times the size of lymphocytes.

A morphological study of the effect of chlorambucil during the S and G2 phases of the cell cycle of synchronized HEp-2 cancer cell populations using computerized morphometry

Chlorambucil, a bisalkylating agent, used extensively in the treatment of autoimmune and neoplastic diseases, is known to affect DNA synthesis. However recent studies have revealed that it also affects the synthesis of other nuclear protein constituents, especially histones. Since histones play a major role in both the structural and functional integrity of chromatin, we have analyzed the morphological effects of this agent, using low dose conditions and synchronized populations of HEp-2 cancer cells in the S and G2 phases of the cell cycle. Analyses at the light and electron microscopy levels were undertaken using synchronous image analysis techniques. Computerized morphometry was used so as to evaluate various nuclear and cytological morphological parameters. It was found that chlorambucil affects the organization of chromatin, as well as other cellular parameters in a manner characteristic of decreased tumor aggressiveness. A finding of significance in this study was that chlorambucil exerted its influence on all these morphological parameters only when treatment was initiated at the beginning of the S phase and not during the second half of the S phase or the G2 phase.

Prognostic value of nuclear morphometry in patients with TNM stage T1 ovarian clear cell adenocarcinoma

In 40 patients with TNM stage T1 ovarian clear cell adenocarcinoma, we used nuclear morphometry to study the relations among morphometric variables, clinical prognostic factors and outcome. The presence of one or more giant nuclear cells was positively associated with death (OR = 10.6, P = 0.02) and tended to be associated with disease recurrence (OR = 5.1, P = 0.07). Nuclear irregularity (expressed in terms of the nuclear roundness factor) was positively associated with both death (OR = 8.6, P = 0.02) and disease recurrence (OR = 8.2, P = 0.02). A combination of giant nuclear cell presence or nuclear irregularity proved to be a useful prognostic indicator, with a sensitivity and specificity of 83% and 71% in the prediction of death, and 75% and 71% in the prediction of disease recurrence. Patients' age and substage were of no prognostic value. We conclude that the nuclear morphometric characteristics, especially the presence of giant nuclear cells and nuclear irregularity, may be useful in predicting outcome in patients with early stage ovarian clear cell adenocarcinoma.

Correlation of nuclear morphometry and immunostaining for p53 and proliferating cell nuclear antigen in transitional cell carcinoma of the bladder

BACKGROUND

In an attempt to determine the biological significance of nuclear morphometric findings, measurements of mean nuclear volume (MNV) and nuclear roundness factor (NRF) were compared to the immunoreactivity of p53 expression and proliferating cell nuclear antigen (PCNA) in human bladder cancer.

METHODS

MNV and NRF were measured using stereological methods. Expression of p53 and PCNA were determined by immunohistochemical staining. Specimens from 111 patients with previously untreated bladder cancer were analyzed.

RESULTS

The mean MNV was 235.8 +/- 133.6 microm3 for the 81 patients with p53-labeling index (LI) less than 10% and 337.2 +/- 141.0 microm3 for the 30 patients with p53 LI greater than 10% (P = 0.008). There was no significant correlation between NRF and expression of p53. The mean MNV was 220.1 +/- 120.5 microm3 for the 67 patients with PCNA LI less than 28% (the mean value of PCNA LI) and 328.9 +/- 149.2 microm3 in 44 patients with PCNA LI greater than 28% (P = 0.0001). The mean NRF was 80.7 +/- 4.2 for the 67 patients with PCNA LI less than 28%, and 82.3 +/- 3.4 for the 44 patients with PCNA LI more than 28% (P = 0.04).

CONCLUSION

Nuclear morphometric findings may reflect the proliferative potential of cancer cells of the bladder, as indicated by findings of immunostaining for p53 and PCNA.