Role of DNA aneuploidy, overexpression of p53 gene product, and cellular proliferation in the progression of gastric cancer.

DNA aneuploidy, p53 overexpression, and high cell proliferation frequently occur in gastric cancer. However, little is known about the time of their appearance throughout cancer progression. Therefore, the objective of the present study was to determine when such abnormalities occur during gastric cancer progression. We classified the gastric cancers examined into intestinal (n = 65) and diffuse (n = 34) types. DNA ploidy was examined using flow cytometry and expression of MIB-1 and p53 immunoreactivity were studied using the avidin-biotin complex method in three stages of gastric cancer (mucosal, submucosal, deeply invasive cancer, i.e., advanced cancer). The incidence of DNA aneuploidy in intestinal-type mucosal cancers (15/27, 55.6%) was lower than that of submucosal invasive cancers (14/16, 87.5%) or advanced cancers (19/22, 86.4%), while a low incidence of DNA aneuploidy was observed in each diffuse-type cancer group (mucosal, 1/12, 8.3%; submucosal invasive, 3/9, 33.3%; advanced, 8/14, 57.1%). Although overexpression of the p53 gene in intestinal-type cancer was found in early stage, that in diffuse-type cancer was observed in advanced stage. Among the intestinal-type mucosal cancers, the MIB-1 percent positive was higher in aneuploid tumors than diploid ones. DNA aneuploidy and overexpression of the p53 gene may play an important role in the early tumorigenesis of intestinal-type gastric cancer and in the late event of tumorigenesis of diffuse-type gastric cancer.     

Evaluation of heterogeneity of DNA ploidy in early gastric cancers.

DNA ploidy has been shown to be a predictive parameter for prognosis in various solid tumours. The prognostic value of DNA-ploidy in gastric cancers is still a matter of controversy. A possible explanation for the discrepant results reported in the literature could be sampling error in tumours with multiple stemlines differing in DNA-ploidy. In order to determine whether or not such heterogeneity exists in early gastric carcinoma, we have performed DNA cytophotometry on multiple samples of a group of 17 early gastric carcinomas, of which 8 were pure intramucosal and 9 were infiltrating into the submucosa. We found an aneuploid DNA-stemline in 8 (47%) early gastric cancers, more often in tumours invading into the submucosa (5/9) than in purely mucosal tumours (3/8). Multiple DNA-stemlines were found more frequently in submucosally infiltrating tumours (4/5). These results confirm the presence of DNA-aneuploid early gastric carcinoma which are frequently heterogeneous and suggest that heterogeneity occurs more frequently in tumours invading the submucosa. This heterogeneity is best detected by analysing multiple samples of tumours for DNA-ploidy.     

DNA ploidy in colorectal cancer, heterogeneity within and between tumors and relation to survival

Flow cytometry was used to study the incidence of aneuploidy and to determine the significance of multiple sampling from colorectal tumors. DNA ploidy pattern has been proposed as a supplementary prognostic marker, but discrepancies in findings are major. DNA clonal heterogeneity, defined as two or more DNA aneuploid stemlines in the same tumor, is well established. However, most studies have been based on only one biopsy from each tumor. In our study multiple biopsies were taken from 163 patients (88 males and 75 females) electively operated for colorectal cancer. Tumor cells were harvested by fine needle aspiration from fresh frozen biopsies sampled at different sites of each tumor. DNA aneuploidy was detected in tumors from 145 patients (89%), and 18 patients (11%) had a solitary DNA diploid cell population. In a 79 month follow-up period 105 patients had died. Statistical analysis showed that distinction between diploidy and aneuploidy did not predict survival. However, grouping subpopulations into DNA diploid plus near diploid (DNA index (DI) 0. 97-1.15), DNA aneuploid with all aneuploid subpopulations in the interval 1.15-2.06, and DNA aneuploid with subpopulations with DI < 0.97 and/or DI > 2.06, showed a significant difference in survival in a Cox multivariate analysis including Dukes' stage P = 0.049 comparing the second group to the first and P = 0.01 comparing the third group to the first. In 21 (13%) patients only one subpopulation was found, 57 (35%) had two, 44 (27%) had three, and 41 (25%) had four or more different subpopulations. The association of DNA ploidy to survival is shown to be dependent on the number of biopsies analysed.     

Genomic profile analysis of diffuse-type gastric cancers

Background

Stomach cancer is the third deadliest among all cancers worldwide. Although incidence of the intestinal-type gastric cancer has decreased, the incidence of diffuse-type is still increasing and its progression is notoriously aggressive. There is insufficient information on genome variations of diffuse-type gastric cancer because its cells are usually mixed with normal cells, and this low cellularity has made it difficult to analyze the genome.

Results

We analyze whole genomes and corresponding exomes of diffuse-type gastric cancer, using matched tumor and normal samples from 14 diffuse-type and five intestinal-type gastric cancer patients. Somatic variations found in the diffuse-type gastric cancer are compared to those of the intestinal-type and to previously reported variants. We determine the average exonic somatic mutation rate of the two types. We find associated candidate driver genes, and identify seven novel somatic mutations in CDH1, which is a well-known gastric cancer-associated gene. Three-dimensional structure analysis of the mutated E-cadherin protein suggests that these new somatic mutations could cause significant functional perturbations of critical calcium-binding sites in the EC1-2 junction. Chromosomal instability analysis shows that the MDM2 gene is amplified. After thorough structural analysis, a novel fusion gene TSC2-RNF216 is identified, which may simultaneously disrupt tumor-suppressive pathways and activate tumorigenesis.

Conclusions

We report the genomic profile of diffuse-type gastric cancers including new somatic variations, a novel fusion gene, and amplification and deletion of certain chromosomal regions that contain oncogenes and tumor suppressors.     

Preferential loss of 5q14-21 in intestinal-type gastric cancer with DNA aneuploidy

BACKGROUND: Little is known about the genetic changes associated with DNA ploidy in gastric cancer (GC). The aim of this study was to identify recurrent or specific chromosomal regions of DNA sequence copy number aberrations (DSCNAs) that might harbor genes associated with DNA aneuploidy in GC. METHODS: We analyzed DSCNAs with comparative genomic hybridization and DNA ploidy by laser scanning cytometry in 16 primary intestinal-type GCs. RESULTS: All GCs examined showed at least one DSCNA (loss or gain); eight were DNA diploid (DD) tumors and eight were DNA aneuploid (DA) tumors. The frequent (>30%) DSCNAs were loss of 5q14-21 and gains of 7p11-14, 8q, 20q, and Xq25-26. Recurrent amplifications (>10%) were detected at chromosomal regions 6p, 7p, and 13q. The overall number of DSCNAs was significantly greater in DA than in DD tumors (P = 0.006). Furthermore, the number of aberrations was clearly greater with 5q loss than without 5q loss (P = 0.002). Losses of 5q14-21, 9p21-pter, 16q, and 18q21-qter were preferentially detected in DA tumors. CONCLUSION: The present observations indicate that there is a close relationship between DSCNA and DNA ploidy in intestinal-type GC and that gene(s) at 5q14-21, 9p21-pter, 16q, and/or 18q21-qter may play important roles in acquisition of DNA aneuploidy.     

DNA ploidy assessment method applied to primary breast carcinoma FNA biopsies

The goal of our study was to assess suitability of FNA biopsy material as a source of samples (cell suspension) for DNA ploidy assessment in neoplastic tumors using flow cytometry. DNA ploidy is an established prognostic factor in many types of cancers. Aneuploid breast tumors are characterized by increased aggressiveness which manifests itself through rapid local progression and metastatic spread. Investigated specimens were breast cancer FNA biopsy cell suspensions. Measurements were performed using flow cytometry. Material studied comprised 143 cases analyzed in 1999-2000. We found in this group 101 carcinoma cases with aneuploid type and 42 cases of primary breast carcinoma with diploid type of cell cycle. Immunocytochemical assesssment of estrogen receptor and progesterone receptor status was performed in group of 105 cases. DNA ploidy was compared to receptor status of the investigated cells. DNA aneuploidy correlated with weak or no reaction for the presence of estrogen and progesterone receptors. Our study demonstrates the suitability of DNA ploidy assessment method applied to cytological material from FNA biopsies.     

Human papillomaviruses and DNA ploidy in anal condylomata acuminata

Previous studies have emphasized the usefulness of DNA ploidy measurement and Human Papillomavirus (HPV) detection as prognostic markers in low grade cervical lesions. We addressed the eventual relationship between HPV type, DNA profile, and p53 tumor suppressor protein expression in anal condylomata acuminata to eventually determine parameters which may be considered as predictive risk factors for the development of cancer. DNA ploidy was assessed by image cytometry after Feulgen staining of contiguous serial sections of 45 anal condylomata acuminata without atypia containing HPV detected by in situ hybridization and Polymerase Chain Reaction (PCR). p53 expression was detected by immunohistochemistry. DNA aneuploidy was found in 53.3% of these lesions, 48.9% containing non oncogenic HPV types 6 and/or 11 and 4.4% harbouring HPV types 11 and 18. The DNA diploid lesions were all associated with non oncogenic HPV types 6 and/or 11 and one case also contained HPV type 33. There was no significant correlation between the detection of DNA aneuploidy and the presence of immuno-detected p53. DNA aneuploidy was not related to the presence of oncogenic HPV in anal condylomata acuminata. The DNA aneuploid profile frequently observed, especially in lesions associated with non oncogenic HPV types, is not yet well explained and cannot be considered as a prognostic factor. In contrast, a more intensive clinical follow-up should be proposed in patients with oncogenic HPV associated to DNA aneuploidy.     

Relationship between immunoexpression of mucin peptide cores MUC1 and MUC2 and Lauren's histologic subtypes of gastric carcinomas

Laurèn's system subdivides gastric cancers into an intestinal type and a diffuse type. This histological classification mirrors histogenetic hypotheses according to which the intestinal-type cancer derives from intestinal metaplasia and dysplasia, while the diffuse-type originates directly from gastric mucosa, with or without a preceding non-metaplastic dysplasia. Studies concerning mucins expression in gastric neoplastic and preneoplastic lesions have provided contradictory data concerning such histogenetic relationships. The aim of the present study was to verify whether a correlation between mucins phenotype and Lauren's classification subsists. 40 gastric adenocarcinomas, subdivided, according to Laurèn's classification, into 27 intestinal-type, 10 diffuse-type and 3 unclassified cases, were examined for MUC1 and MUC2 immunohistochemical expression. Intestinal-type carcinomas displayed a MUC1-positive staining in 23/27 cases and a MUC2-positive immunoreaction in 10/27 cases. Diffuse-type carcinomas expressed MUC1 in 3/10 and MUC2 in 8/10 cases, respectively. According to the mucins expression pattern, three phenotypes were identified: the gastric phenotype (MUC1+/MUC2-); the gastro-intestinal phenotype (MUC1+/MUC2+) and the intestinal phenotype (MUC1-/MUC2+). The gastric phenotype was significantly higherin intestinal-type adenocarcinomas, whereas cases showing an intestinal phenotype were significantly more frequent in diffuse-type adenocarcinomas. These findings provide evidence for a lack of correlation between Lauren's classification and MUC1 and MUC2 phenotypes. In particular, the term intestinal-type tumour as referred to gland-forming gastric cancer does not seem to reflect an immunohistochemical phenotype.     

DNA ploidy and S-phase fraction in carcinoma of the gallbladder related to histopathology, number of gallstones and survival.

Gallstones are a risk factor for the development of gallbladder cancer. We studied DNA ploidy and cell cycle composition by flow cytometry in archival specimens from 52 gall bladder carcinomas in relation to histopathological grade, tumour stage, gallstone number and survival. 69% of the gallbladder carcinomas showed aneuploidy. All tumours with single stones (N=11) were aneuploid while only 61% of tumours with multiple stones (N=41) were aneuploid (p=0.002). DNA aneuploidy was related to increase in T-category (p=0.01), grade (p=0.02), and nuclear pleomorphism (p=0.0005). The distribution of DNA ploidy shifted from tetraploid in low stage towards triploid positions in high stage tumours (p=0.02) combined with higher S-phase values in triploid tumours (p=0.05). S-phase fraction increased during development from normal tissue to dysplasia, cancer in situ and cancer in diploid cases (p=0.0002), and further at the change from diploid to aneuploid (p=0.004). At a median cancer specific survival time of four months patients with diploid tumours had a better survival than those with aneuploid tumours (p=0.02). In multivariate analysis of the tumour characteristic, only T-category and tumour grade were independent prognostic factors.The shift from diploid to aneuploid and the further shift of ploidy within aneuploid tumours are in agreement with the concept of a clonal development of gallbladder cancer. These changes are combined with a stepwise increase in the fraction of S-phase cells. Low frequency of symptoms in single stone patients may be the reason for detection of malignancy at a late stage of tumour development.     

Comparison of image analysis with flow cytometry for DNA content analysis in pigmented lesions of the skin.

The DNA ploidy of 85 melanocytic skin lesions was determined by flow cytometry (FCM) and interactive image analysis (IA) using nuclear extracts of paraffin-embedded tissue. Of the 85 lesions analyzed, 43 were malignant melanomas in different stages of evolution, 15 were dysplastic nevi, 11 were Spitz nevi, and 16 were other types of nevi. Some of the last had features of congenital nevi. Within the melanoma category, there was 42% aneuploidy by FCM versus 56% by IA. Of those melanomas aneuploid by FCM, all but one were aneuploid by IA. All dysplastic nevi, 10/11 Spitz nevi and 15/16 other nevi were diploid by both methods. One of the 16 nevi from the "other types" category was tetraploid by IA but diploid by FCM. A single Spitz nevus was tetraploid by FCM but diploid by image analysis. While our results suggest that interactive IA is potentially a more sensitive method than FCM for detecting aneuploidy in cutaneous pigmented lesions, it remains to be shown whether this will translate into better prognostic assessment of the biologic behavior of melanocytic neoplasms than provided by flow cytometric ploidy analysis.     

A strategy combining flow sorting and comparative genomic hybridization for studying genetic aberrations at different stages of colorectal tumorigenesis in ulcerative colitis

BACKGROUND: DNA aneuploidy has been shown to increase the risk of developing dysplasia in ulcerative colitis (UC) and is related to tumorigenesis in the colorectum. Therefore, it is of particular interest to study genetic aberrations behind DNA aneuploidization during colorectal carcinogenesis. We wanted to elucidate further the relationship between mucosal morphology and DNA aberrations in UC. METHODS: DNA flow cytometry was applied to multiple lesions including regenerative, dysplastic, and carcinomatous mucosa from the colectomy specimen of a male patient with long-standing UC. The lesions harbored multiple DNA aneuploid stemlines that were subjected to flow sorting. We analyzed gene alterations by degenerate oligonucleotide primer (DOP; universal primers) polymerase chain reaction (PCR)-based comparative genomic hybridization (CGH) and fluorescent in situ hybridization (FISH) in diploid and aneuploid sorted cells. RESULTS: DOP-PCR-based CGH shows gains and losses that can be verified by FISH. We show that with this approach one can study genetic evolution of distinct DNA diploid and aberrant subpopulations through defined stages of colorectal tumorigenesis. This includes getting information related to tumor heterogeneity that cannot be obtained by CGH with DNA extracted from nonsorted cell populations. Genetic imbalance was also detected in diploid nondysplastic flow-sorted mucosal cells from the same bowel. CONCLUSIONS: Similar gains and losses were found in aneuploid dysplasias and carcinomas at widely separated locations in the same bowel, indicating a common selection pressure in different areas of the same bowel. The common aberrations may be of importance for progression from dysplasia to carcinoma.     

DNA ploidy and chromosomal imbalances in invasive ductal breast cancer. A comparative study of DNA image cytometry and comparative genomic hybridization (CGH).

Chromosomal imbalances were analyzed in 62 breast cancers with different DNA ploidy by CGH. The results of DNA image cytometry and CGH are consistent with peridiploid and aneuploid cases. The peritetraploid tumors harbored a high number of chromosomal imbalances, as a hint for an unfavorable prognosis. The quantitative analysis of imbalances highlighted the role of different physical constituents of the chromosome, and of chromosomal losses in different DNA ploidy groups. The peritetraploid and aneuploid tumors differed from the peridiploid tumors in losses at 8p and 18q. The peritetraploid cancers exhibited more gains at 8q, the aneuploid tumors more losses at 17p than their peridiploid counterparts. The aneuploid cases differed from the peritetraploid tumors in a higher number of losses at 11q and 14q. Combinations of imbalances provide further insights into the genetic background of DNA ploidy. Hypotheses for the progression from peridiploid to nondiploid breast cancers are given.     

DNA ploidy pattern and amplification of ERBB and ERBB2 genes in human gastric carcinomas

The DNA ploidy pattern and amplification of ERBB and ERBB2 genes were examined in paraffin-embedded tissue from gastric carcinomas using flow cytometry and a slot-blot hybridization technique. The incidence of aneuploidy in well differentiated adenocarcinomas (56%) was significantly higher (p less than 0.05) than that in poorly differentiated adenocarcinomas (21%). The DNA ploidy pattern was not remarkably different between the primary tumors and metastatic deposits in lymph nodes. Of the nine specimens having an aneuploid stem cell line in the primary tumor and/or in metastases, three showed ERBB2 gene amplification and one showed ERBB gene amplification. The incidence of epidermal growth factor (EGF) immunoreactivity in tumor cells showed no difference between diploid and aneuploid tumors. These findings indicate that aneuploidy is frequently associated with amplification of ERBB and ERBB2 genes.     

DNA ploidy and survival in breast cancer patients

Flow cytometric DNA ploidy measurements using frozen or deparaffinized tumor specimens were performed on 565 primary breast cancers from patients treated in the period 1975-1984. Twenty-nine percent of the cases were diploid, 61% had a single aneuploid stemline, and 10% were multiploid. Aneuploid tumors more often had negative estrogen receptor values than diploid tumors, but no significant correlation was found between ploidy class and TNM stage. Patients with more than ten positive axillary lymph nodes had predominantly aneuploid tumors. Overall and distant relapse-free survival were higher for patients with diploid tumors and low-aneuploid tumors. Stratification of the patients according to degree of lymph node involvement, TNM stage, and menopausal stage showed that the prognostic effect of aneuploidy was apparent predominantly in patients with locally advanced disease. Postmenopausal node-positive patients with diploid tumors had a significantly better prognosis than those with aneuploid tumors, but this difference was not found for the comparable premenopausal group. Multivariate analysis with the Cox proportional hazards model indicated that ploidy is an additional, independent prognostic factor in postmenopausal patients.     

DNA ploidy pattern and amplification of ERBB and ERBB2 genes in human gastric carcinomas

The DNA ploidy pattern and amplification of ERBB and ERBB2 genes were examined in paraffinembedded tissue from gastric carcinomas using flow cytometry and a slot-blot hybridization technique. The incidence of aneuploidy in well differentiated adenocarcinomas (56%) was significantly higher (p<0.05) than that in poorly differentiated adenocarcinomas (21%). The DNA ploidy pattern was not remarkably different between the primary tumors and metastatic deposits in lymph nodes. Of the nine specimens having an aneuploid stem cell line in the primary tumor and/or in metastases, three showed ERBB2 gene amplification and one showed ERBB gene amplification. The incidence of epidermal growth factor (EGF) immunoreactivity in tumor cells showed no difference between diploid and aneuploid tumors. These findings indicate that aneuploidy is frequently associated with amplification of ERBB and ERBB2 genes.     

Reduced level of the spindle checkpoint protein BUB1B is associated with aneuploidy in colorectal cancers

Abstract.   Objectives : The majority of solid human malignancies demonstrate DNA aneuploidy as a consequence of chromosomal instability. We wanted to investigate whether Aurora A, Aurora B, BUB1B and Mad2 were associated with the development of aneuploidy in colorectal adenocarcinomas as suggested by several in vitro studies, and if their protein levels were related to alterations at the corresponding chromosomal loci. Materials and methods : Expression levels of these spindle proteins were investigated by immunohistochemistry using tissue micro-arrays in a series of DNA aneuploid and diploid colorectal adenocarcinomas previously examined for genomic aberrations by comparative genomic hybridization. Results : All proteins were overexpressed in malignant tissues compared to controls ( P <  0.001 for all). BUB1B level was significantly reduced in aneuploid compared to diploid cancers ( P =  0.001), whereas expression of the other proteins was not associated with DNA ploidy status. High levels of Aurora A ( P =  0.049) and low levels of Aurora B ( P =  0.031) were associated with poor prognosis, but no associations were revealed between protein expression and genomic aberration. Conclusions : A significant reduction of BUB1B level was detected in aneuploid compared to diploid colorectal cancers, consistent with earlier studies showing that loss of spindle checkpoint function may be involved in development of DNA aneuploidy. Our data also show that spindle proteins are overexpressed in colorectal cancers, and that expression of the Aurora kinases is associated with prognosis in colorectal cancer.     

Different opinions on classification of DNA histograms produced from paraffin-embedded tissue

Flow cytometric DNA ploidy determination has been regarded as an objective prognostic parameter in several types of human cancer. To test whether DNA histograms are similarly interpreted, a series of flow cytometric DNA histograms was posted to six investigators working in the field for independent classification. The histograms were produced from paraffin-embedded adrenal adenomas or non-neoplastic tissue and had several different patterns. Only 44% of the histograms were similarly classified by all investigators, and 85% by five of the six participants, when DNA ploidy was evaluated. Different criteria for tetraploidy existed, and also some uncertainty in classifying peridiploid and small aneuploid peaks. It is concluded that lack of consensus on histogram classification may result in widely varying percentages of DNA aneuploid tumors found even if the data are similar. Until general agreement is reached on the definition of DNA aneuploidy and its subclasses, classification of DNA histograms is variable and subjective.     

Prospective study on prognostic significance of DNA ploidy and Ki-67 expression in colorectal cancer

The aim of the study was to correlate tumoral DNA ploidy and Ki-67 expression with therapy response, Overall Survival (OS), Disease Specific Survival (DSS) and Disease Free Survival (DFS). Three samples of colorectal cancer were collected from each patient. One sample of normal tissue was our internal control. DNA ploidy was evaluated by FACSCalibur cytometer and Ki-67 by immunohistochemistry. We studied 67 patients and we found aneuploidy in 65,7 percent of carcinoma with a Ki-67 median expression of 55 percent. After surgery and chemotherapy in 35 percent of the patients with aneuploid carcinoma and high proliferative activity (Ki-67 greater than 55 percent) there were no evidence of disease versus 100 percent of patients with DNA diploidy and low proliferative activity (Ki-67 less than 55 percent). Tumoral aneuploidy significantly correlated with lower OS, DSS and DFS (18 percent vs 86 percent at 30 months). Univariated analysis demonstrated a significant correlation between aneuploidy and develop disease progression (p=0,033, odd ratio=5.7), while the cut-off of 55 percent for Ki-67 expression did not correlate with OS, DSS and DFS. Preliminary results (the study is still in progress) seemed to suggest that DNA ploidy has a prognostic and predictive significance in colorectal carcinoma.     

Comparison of the intratumor DNA ploidy distribution pattern between differentiated and undifferentiated gastric carcinoma

OBJECTIVE: To compare the differences in intratumor DNA ploidy distribution pattern between differentiated and undifferentiated carcinoma of the stomach. STUDY DESIGN: Two hundred five cases of surgically resected gastric carcinoma were studied, comprising 125 differentiated and 80 undifferentiated carcinomas. DNA ploidy was determined by means of flow cytometry in stepwise sections of the entire tumor. The intratumor DNA ploidy distribution pattern was compared between these two histologic types. RESULTS: Differentiated carcinomas comprised 35 cases of predominantly diploid (28%) and 90 cases of predominantly aneuploid (72%) tumors, while undifferentiated carcinomas comprised 46 cases of predominantly diploid (57.5%) and 34 cases of predominantly aneuploid (42.5%) (P < .01). The frequency of cases showing predominantly aneuploidy among the differentiated carcinomas was significantly higher than among the undifferentiated carcinomas at stages IA and IIIA. The rate of cases showing heterogeneity was lower among the early-stage cases than among the advanced-stage cases in both histologic types. Among the differentiated carcinomas, there were 22 cases that had more than six DNA stemlines in each tumor, whereas among undifferentiated carcinomas, there were six such cases (P < .05). CONCLUSION: There were more cases with high malignant potential among the differentiated carcinoma cases than among the undifferentiated carcinoma cases in the present series.