Flow cytometric DNA ploidy in colorectal adenomas and family history of colorectal cancer

Ploidy and Proliferation Evaluated by Flow Cytometry. An Overview of Techniques and Impact in Oncology

Flow cytometric methods for the assessment of nuclear and chromosomal DNA content and of cell proliferation (including methods based on pulse-chase of bromodeoxyuridine and on monoclonal antibodies against nuclear oncoproteins and proliferation-associated antigens) are illustrated by examples and analyzed critically. The impact of most of these techniques for the study of human solid tumors, with exception of nuclear DNA content evaluation, appears still limited. In particular, new studies of cell lines and clinical material from human tumors using new proliferation markers and multiparameter flow cytometry are necessary to solve a considerable number of methodologic and scientific problems.

Genomic instability--the engine of tumorigenesis?

Human cancers harbour numerous mutations and it has been proposed that these result from some form of inherent genomic instability. Some cancers have proven genomic instability or features that are indicative of this. Inherited cancer syndromes exist that are caused by deficient DNA repair or chromosomal integrity. By contrast, theoretical analysis and experimental data from sporadic colorectal tumours provide little general evidence of genomic instability in early lesions. These apparently conflicting data raise the question of whether or not genomic instability is necessary for driving tumour growth, and whether or not it is the usual initiating event in tumorigenesis.

Colorectal cell kinetics

The assessment of cell proliferation in colorectal tissue may provide information with both prognostic and therapeutic implications. A variety of methods are available, including flow cytometric estimations of S phase fraction, immunohistochemical and autoradiographic visualization of exogenous and endogenous proliferation proteins, and morphological and stathmokinetic techniques. There is some correlation between Dukes stage and proliferation state features, and there is increased proliferative activity throughout the adenoma-carcinoma sequence. Data on cell proliferation rates are difficult to obtain. When correctly applied, the metaphase arrest technique remains the 'gold standard' of measuring proliferation, but its usefulness in clinical practice is limited. Recent studies have employed dual measurement flow cytometry and double labelling techniques to produce rate data.

K-ras-2 G-C and G-T transversions correlate with DNA aneuploidy in colorectal adenomas

BACKGROUND/AIMS

K-ras-2 mutations and DNA content heterogeneity represent early events of human colorectal tumor progression. The aim of the study was to investigate if specific K-ras-2 mutations in 58 human sporadic adenomas were correlated with DNA aneuploidization and cell proliferation.

METHODS

Multiparameter flow cytometry, based on scatter parameters and DNA content, was performed using 4,6-diamidino-2-phenilindole-2-hydrochloride-stained nuclei obtained from adenoma fragments with either mild-moderate or severe dysplasia. K-ras-2 polymerase chain reaction and spectrum analysis were performed using sorted DNA specific epithelial subclones.

RESULTS

We detected six G-A transitions, and four G-C and two G-T transversions. The DNA aneuploid subclones were 25 with DNA index values in the near diploid region (DNA index < 1.3) for the vast majority of cases (80%). DNA aneuploidy among the mutated adenomas with G-A transitions was 1 of 6 (17%) and 6 of 6 (100%) among G-C and G-T transversions. Although DNA aneuploidy and high S-phase values were also present among K-ras-2 wild-type adenomas, their statistical associations with K-ras-2 status were P < 0.005 and P < 0.05, respectively.

CONCLUSIONS

The present series of sporadic colorectal adenomas indicates that codon 12 G-C and G-T K-ras-2 transversion mutations and DNA aneuploidy are correlated. The underlying mechanisms that explain such association remain to be investigated.

The clinical and genetic manifestations of hereditary nonpolyposis colorectal carcinoma

BACKGROUND

Hereditary nonpolyposis colorectal cancer (HNPCC) is a syndrome that affects a significant percentage of the total cancer population but is not easily recognized because of a lack of a distinctive clinical marker such as multiple polyps.

DATA SOURCES

The present review discusses the clinical characteristics, pathology, genetics, management, and surveillance of HNPCC. The diagnosis of HNPCC is dependent upon family history. It is defined by the Amsterdam criteria consisting of: (1) 3 or more relatives with histologically verified colorectal carcinoma, 1 of whom is a first-degree relative of the other 2; (2) colorectal carcinoma involving at least two generations; and (3) one or more colorectal carcinoma cases diagnosed at less than 50 years of age.

CONCLUSIONS

The diagnosis of HNPCC requires the demonstration of vertical transmission of the syndrome in the family pedigree. Attention should be focused on reports of cancer of all anatomic sites and the determination of site, histology, and age at diagnosis.

Application of the crypt-isolation technique to flow-cytometric analysis of DNA content in colorectal neoplasms

BACKGROUND/AIMS

Conventional flow-cytometric analysis of colorectal tumor DNA content includes both tumor and stromal cell DNA. To improve the method, we evaluated the DNA content of purified epithelial cells using the crypt-isolation technique.

METHODS

Normal and neoplastic crypts were isolated from fresh resected colorectum nonenzymatically. Isolated crypts were digested into single nuclei suspensions and examined by flow cytometry (FCM). Internal controls from normal crypts were used to define diploidy. The neoplastic nuclei in the same individual and mixtures of both normal and neoplastic nuclei in various ratios were analyzed.

RESULTS

Tumors having both diploid and aneuploid stemlines were found more frequently than that reported using conventional FCM. Near-diploid DNA stemlines with DNA indices ranging between 0.90 and 1.10 were detectable. The cases of advanced cancer in which the DNA index was between 0.90 and 0.95 were associated significantly with Dukes' stage C.

CONCLUSIONS

This is the first reported analysis of the DNA content of "pure" neoplastic colorectal epithelia using FCM. Multiploid and near-diploid stemlines were more accurately analyzed than that using conventional FCM.

DNA mapping of colorectal neoplasms: a flow cytometric study of DNA abnormalities and proliferation

BACKGROUND

There is some evidence that neoplastic development and progression evolve through a multistep process associated with hyperproliferation and genetic alterations. Therefore, changes of proliferation and of cellular DNA content within the adenoma-carcinoma sequence were studied.

METHODS

Using a "mapping" procedure, 12 adenomas and 18 carcinomas were analyzed flow cytometrically and histologically. In addition, normal mucosa adjacent to and distant from the tumors was assessed in the same way.

RESULTS

Of 59 adenomatous fractions, 35.6% (n = 21) were aneuploid, whereas the incidence of aneuploidy was 63.5% (54/85) in the carcinomatous sites. Additional tetraploidies were identified in 5 (8.5%) and 13 (15.3%) adenomatous and carcinomatous samples, respectively. Cell proliferation, as determined by the percentage of S-phase cells, was significantly (P < 0.001) higher in the carcinomatous specimens (14.8% +/- 0.8%; mean +/- SEM) than in the adenomatous ones (8.1% +/- 0.7%). It decreased to normal mucosa adjacent to (5.1% +/- 0.5%) and distant (5.3% +/- 0.6%) from the neoplasms. DNA mapping of the tumors revealed both distinct regions and extended areas of aneuploidy and tetraploidy. There is evidence from the mapping data that aneuploid populations arise at a single focus of the adenoma and expand over large areas before a subpopulation of cells acquires the capacity of invasion.

CONCLUSIONS

These data showing consecutive DNA content abnormalities within the colorectal adenoma-carcinoma sequence provide support for genomic instability and clonal evolution as important events of tumorigenesis and progression.

DNA image cytometric analysis of macroregenerative nodules (adenomatous hyperplasia) of the liver: evidence in support of their preneoplastic nature

Twenty-eight macroregenerative nodules from 14 cirrhotic patients who underwent orthotopic liver transplantation were evaluated for DNA ploidy by means of image analysis of Feulgen-stained tissue sections. The lesions were classified as type 1 (16 cases) or type 2 (12 cases) on the basis of the absence or presence of cellular or architectural atypia in the nodules. The surrounding cirrhotic nodules were evaluated for liver cell dysplasia. Aneuploid peaks were significantly more frequent in type 2 macroregenerative nodules (58.3%) than in the cirrhotic regenerative nodules (7.1%) (p < 0.007). In addition, aneuploid peaks occurred with increased frequency in type 2 nodules (58.3%) than in type 1 macroregenerative nodules (6.2%) (p < 0.02). Only two aneuploid peaks (14.2%) were found in dysplastic cirrhotic livers. The nuclear area of aneuploid hepatocytes (71.6 microns 2 +/- 10.1%, mean +/- S.D.) differed significantly from that of diploid liver cells (45.4 microns 2 +/- 6.5%) (p < 0.0001). Tetraploid peaks occurred in three type 2 lesions (25%); they were also found in one type 1 macroregenerative nodule (6.2%), one cirrhotic liver without dysplasia (7.1%) and three cirrhotic livers with dysplasia (21.4%). These findings support the notion that macroregenerative type 2 nodules are directly implicated in hepatocarcinogenesis and that their presence should be sought as an indicator of malignant potential in cirrhotic livers.

Association of aneuploidy in index adenomas with metachronous colorectal adenoma development and a comparison

BACKGROUND

Features of index adenomas in the colorectum may be important for the prediction of metachronous adenoma development.

METHODS

Complete colonoscopic follow-up for a mean period of 10 years was achieved in 70 of 124 patients after endoscopic polypectomy of an adenoma from the colorectum. On the basis of the clinical outcome, the patients were divided into three groups: Group I, patients who had a colorectum free of adenomas and cancer; Group II, patients who had one or more metachronous adenomatous polyps; and Group III, patients who subsequently had a colorectal carcinoma. The clinical characteristics of the patients were collected, and the neoplastic specimens were re-examined with regard to pathologic parameters and flow cytometrically determined nuclear DNA content.

RESULTS

Aneuploid stemlines were found in 35% of the index adenomas. Significantly more aneuploid adenomas were found in the index adenomas of Group I patients than in the adenomas of Group II patients (r = -0.20; P = 0.05). However, in the index adenomas of Group II patients, aneuploidy was associated with villous architecture (P < 0.05) and inversely related to cellular atypia (P < 0.05). Such relations were not found in the adenomas from Group I. In addition, in the Group II adenomas, aneuploidy was found frequently in the more proximally localized adenomas in the large intestine. Remarkably, all adenocarcinomas of the Group III patients were localized in the right colon. No significant differences were found in ploidy and mean DNA index between index adenomas and metachronous adenomas of the Group II patients. However, the ploidy class of the index adenomas was found not to be related to that of the metachronous adenomas in the individual patients.

CONCLUSIONS

These results demonstrate that DNA cytometry in adenomas alone is not helpful in the prediction of the possibility of the development of a metachronous adenoma. However, aneuploidy in a villous adenoma located more proximally in the colon might indicate a higher risk for metachronous neoplasia development. Index and metachronous adenomas are similar in DNA content but show no relation with respect to ploidy class.

Long-term endoscopic and flow cytometric follow-up of colon interposition

During 1963 to 1978 colon interposition was performed on 20 children. Early and late mortality accounted for 3 patients and two transplants failed. Of the 15 long-term survivors, subjective results were obtained from 12 patients 12 to 26 years after the reconstruction. Three patients had an excellent subjective result and 9 had a good result. Nine patients underwent esophagogastroduodenoscopy 12 to 26 years after the reconstruction. The endoscopic findings included: marked tortuosity or dilatation (6), pooling of bile or yellow bezoar (3), macroscopic colitis (3), and polyps in the distal anastomosis (2). Only two patients had a straight colon tube without mucosal changes or marked retention. Specimens for histology were obtained in each endoscopy. Colitis was found in 3 patients, 1 patient had gastric metaplasia in the transplant, 1 patient had dysplasia of colonic mucosa and an inflammatory colonic polyp, and in 4 patients histology showed normal colonic mucosa. Flow cytometric samples were obtained from 8 patients. Two showed an aneuploid cell population; the other 6 had normal diploid findings. Because of frequent endoscopic and histological changes, regular endoscopic follow-up of these patients is warranted.

Quantitative study of the precancerous and malignant lesions in colorectal adenomas

150 endoscopically removed colorectal adenomas are quantitatively studied. In 90 cases dysplastic glands constituted the entire lesion (30 mild, 30 moderate, 30 severe); in 60 cases foci of adenocarcinoma were present (30 intramucosal, 30 submucosal). In each case the area, the perimeter and the integrated optical density of 100 nuclei were measured from Feulgen-stained paraffin sections. The results show a continuous neoplastic progression in the trends of the morphometric parameters as well as in the ploidy pattern. The stepwise discriminant analysis defined the morphometric features of the atypical nuclei, which were present in small numbers also in mild dysplasia; they progressively increased in number, reaching the maximum in submucosal carcinoma.

Clinical application of flow cytometry for DNA analysis of solid tumors

Recent developments of flow cytometry (FCM) technology which make multiple correlative biological measurements on normal and neoplastic cells is affecting areas of diagnostic pathology as well as research fields, and a general understanding of FCM techniques is essential for pathologists. Today, FCM DNA measurements of tumors also becomes routine in the clinical and/or pathological laboratory for aid in cancer diagnosis and cancer treatment. It can also contribute to diagnosis of tumors as a supplemental method to conventional histopathology, and DNA ploidy and the percentage of S-phase fraction are considered as complementary prognostic parameters independent of the stage of disease. This article reviews clinical applications of flow cytometry focusing on the DNA measurements of solid tumors, and related practical issues, such as the methodology for nuclear DNA measurement, interpretation of DNA histograms and the relationship of DNA ploidy and S-phase fraction to clinical and pathological features of human solid tumors.

Flow cytometric DNA index in the prognosis of colorectal cancer

The authors investigated the relationship between flow cytometric DNA index (DI, defined as the ratio of the DNA content of malignant cells to that of normal cells) and other prognostic factors (grade and stage, anatomical site, age and sex) with the survival of 115 patients with colorectal cancer. Multiple biopsy specimens from 62 patients were taken during colonoscopy before surgery. Additional samples from 53 patients were obtained from paraffin-embedded material. All patients were treated with surgery only. Fresh-frozen material gave higher incidence of DNA aneuploidy than paraffin-embedded material (79% versus 41%). The patients with DNA diploid tumors (DI = 1) had a better overall survival than those with DNA aneuploid tumors (DI = 1). Among DNA aneuploid tumors, those with DI greater than 1.2 (excluding DI = 2) were worse than those with DI = 1.2 (excluding DI = 1) and DI = 2. Cox's regression analysis showed that pathologic stage was more important for prognosis than DNA index, whereas age, sex, histologic grade, and anatomic site were removed from the analysis as not relevant for prognosis. Relative risk of death (RR), in reference to patients with DI = 1 and Stages A + B (RR = 1), were RR = 1.8 for patients with carcinomas with Stage C. RR = 2.7 for patients with carcinomas with DNA near-diploid and DNA tetraploid tumors. RR = 3.5 for those with DI greater than 1.2 (excluding DI = 2), and RR = 8.0 for those with Stage D. These data indicate that flow cytometrically evaluated DI values have a relevant independent power for predicting the clinical outcome of colorectal cancer patients.

DNA flow cytometry of hereditary and sporadic paragangliomas (glomus tumours)

Paragangliomas (glomus tumours) are benign, hypervascular tumours which in general are treated by surgical excision. The indication for treatment of these often slow-growing tumours needs additional criteria for predicting tumour progressiveness. For this reason the nuclear DNA content of 99 paragangliomas, 65 of them originating from patients with a positive family history, was analysed by flow cytometry. Unequivocal evidence of DNA aneuploidy was found in 37% of these clinically and histologically benign tumours, the average duration of follow up amounting to at least 10 years. The DNA index of the aneuploid tumours ranged from 0.90 to 2.03. No correlation was found between DNA ploidy and familiality or between DNA content and clinical criteria indicative of tumour progression, which means that DNA ploidy of these tumours cannot serve as a predictor for an expected growth pattern or familiality. DNA aneuploidy in hereditary and sporadic paragangliomas is not clinically related to malignancy, but indicates that these tumours are true neoplasias cytogenetically.

Proliferation characteristics of human colorectal carcinomas measured in vivo

The cell proliferation kinetics of 100 human colonic and rectal adenocarcinomas have been studied in vivo by bromodeoxyuridine infusion and multiparameter flow cytometry. A total of 97 patients, three with synchronous tumours, consented to receive a single bolus dose of 250 mg between 2.4 and 16 h before curative or palliative surgery. By this method, the ploidy pattern, the total and aneuploid labelling indices (LI), the S phase duration (Ts) and the potential doubling time (Tpot) can be estimated. Of the tumours 48 were diploid and 52 were aneuploid. The mean and median total LI of 100 tumours were 9.0 per cent (range 0.7-22.2 per cent). The mean aneuploid LI was 12.1 per cent (median 12.0 per cent, range 2.0-25.5 per cent), and was significantly higher than the total LI (P = 0.01). The labelling index alone is not a sufficient indicator of proliferation, because the Ts also varies within and between tumours. The intertumour range of the Ts varied from 4.0 to 28.6 h. The mean was 14.1 h and the median was 13.1 h. The mean Tpot was 5.9 days (median 3.9 days) with a range of 1.7-21.4 days. No correlation was found between any kinetic parameters and the Dukes' classification or histological classification. The correlation between proliferation and prognosis will be established in due course.

DNA measurements in chronic hepatitis, cirrhosis and hepatocellular carcinoma

It has been documented that chronic hepatitis may progress to cirrhosis and then develop hepatocellular carcinoma (HCC). To test whether abnormal cellular DNA increases along this line of development, liver tissues from 48 patients with chronic hepatitis, 17 with cirrhosis, and 8 with HCC were investigated for cellular DNA content with a scanning microdensitometer. Seven of 8 HCCs and 2 cirrhotic livers adjacent to HCC had abnormally increased cellular DNA content. Only 4 livers from patients with chronic liver diseases other than HCC had abnormal cellular DNA content. The cellular DNA content in livers not accompanying HCC was not related to the patient's age, histological diagnosis, and hepatitis inflammatory activity. The results confirmed the increase of cellular DNA content in HCC, but did not provide evidence of a progressively increasing DNA content from chronic hepatitis to liver cirrhosis. However, cirrhotic livers with abnormal hepatocytic DNA content deserve careful follow-up for the early detection of HCC.

Tumor progression by DNA flow cytometry in human colorectal cancer

We wished to better understand the role of aneuploidy during the progression of human colorectal cancer. Fresh or frozen multiple samples from 221 human colorectal adenomas, 93 carcinomas, and corresponding control mucosa were investigated using high-resolution DNA flow cytometry. A total number of 164 DNA abnormal clones were observed and characterized by a quantitative index of DNA aneuploidy (DI). In precancerous lesions the vast majority of DNA abnormal clones (almost 3/4 in adenomas with mild to moderate dysplasia) was hypo- and hyper-diploid with DI values from 0.8 to 1.2 (near-diploidy). In moderately to poorly differentiated carcinomas the vast majority of abnormal clones was near-triploid and hypotetraploid with DI values from 1.4 to 1.8 (near hypertriploidy) and only 12% were near-diploid. Adenomas with foci of carcinomas, a group of special interest since they represent a link in colorectal tumor progression, had median triploid DNA content. In addition to an increase in DI values, the carcinomas had a clear increase in the proportion of cells actively synthesizing DNA (S-phase fraction). These results are interpreted as evidence for a ploidy-evolution model according to which near-diploid clones in adenomas at early stages of dysplasia would derive from abnormal mitotic cells that divide their DNA unequally between two daughter cells. Tetrapolidization of these near-diploid cells and successive DNA loss would then lead in later stages of tumor progression to near-hypertriploid clones characterized by a balance of chromosomes bearing growth-promoting and growth-suppressing genes confering a selective proliferative advantage.

Ploidy, proliferative activity and prognosis. DNA flow cytometry of solid tumors

Flow cytometric study has been used to measure the cellular DNA content of solid tumors for the last decade, and of paraffin-embedded tumor specimens for the last 5 years. Ploidy and proliferative activity are the two properties commonly measured by DNA content flow cytometric study. The ability to study archival, paraffin-embedded tumors has hastened an appreciation of the prognostic utility of this assay. Either abnormal ploidy or elevated proliferative activity predict a worsened disease-free or overall survival in most common adult malignancies. Both abnormalities are associated with poor outcome in locoregional breast, non-small cell lung, and colorectal cancers, and in all stages of ovarian cancer. Abnormal ploidy is also a dire prognostic indicator for cancers arising from the kidney, bladder, prostate, and endometrium. Clinical management of patients with these diseases may be aided by studying their tumors for these objective markers of biological aggressiveness.

DNA flow cytometry of endoscopically examined colorectal adenocarcinomas

The purpose of the study was to evaluate the correlation of DNA-ploidy of colorectal adenocarcinomas (adk) with histological and clinical parameters including the survival of the patients. Multiple biopsies from 95 adk were taken during colonoscopy prior to surgery. The samples were used to obtain nuclei suspensions for specific staining of DNA content and high resolution flow cytometry. DNA-aneuploidy, i.e. the presence of more than one G0/G1 peak, was detected in 67/95 cases (71%). The individual-specific control mucosa was DNA-diploid in all cases. The mean fraction of S-phase cells was 7.2% in control mucosa and 13.6% in adk. DNA-ploidy did neither correlate with Dukes' stage nor with differentiation degree. Among the patients studied for the correlation of DNA ploidy with survival for a period extending to 30 months (n = 51), the DNA aneuploid group was estimated to be about 5 times as risky as the DNA diploid group with respect to the odds of dying. We conclude that DNA flow cytometry of colorectal adk may predict clinical outcome and be helpful in addition to histopathology.

DNA flow cytometry of endoscopically examined colorectal adenomas and adenocarcinomas

DNA ploidy of 64 colorectal adenomas and 49 adenocarcinomas, examined endoscopically, was studied by flow cytometry. We found DNA aneuploidy in none of the 105 normal mucosa samples (0%), in 20 adenomas (31%), and in 36 adenocarcinomas (74%). DNA ploidy of adenomas correlated with size (P = 0.02) and degree of dysplasia (P less than 0.01) but not with histologic type. Adenomas had a 45% incidence of DNA aneuploid stem lines in the DNA index range of 0.80-1.20, compared with 8% in the case of adenocarcinomas. The distribution of the DNA index values of adenocarcinomas was approximately normal, with a mean value 1.63 +/- 0.28. The mean DNA index for the three cases of "carcinoma in adenoma" with invasion of the stalk of the adenoma was 1.52 +/- 0.18. These results, using DNA flow cytometry, provide evidence for the progression of colorectal adenoma to adenocarcinoma. The classification of adenomas according to DNA ploidy may be information of considerable practical value to the clinician in predicting risk of further adenomas and/or risk of cancer.