Ploidy analysis of field cancerization and cancer development in the hamster cheek pouch carcinogenesis model

BACKGROUND: The hamster cheek-pouch carcinogenesis model is a well-known animal system that closely mimics the development of premalignant and malignant lesions in human oral cancer. Our aim was to numerically characterize the premalignant and malignant lesions and expressions of field cancerization in this model using ploidy as the end-point. METHODS: To study the DNA content and proliferation status of the cells in this model we assessed the Feulgen reaction and the immunohistochemical reaction for 5-bromo-2-deoxiuridine (BrdU) in different histological areas of serial tissue sections of the cheek pouches of animals injected with BrdU. RESULTS: Ploidy values were higher in cancerized epithelia with no unusual microscopic features (NUMF), in preneoplastic and tumor areas than in control epithelia. The aneuploidy index was higher in NUMF areas than in control and differed significantly from control in preneoplastic areas and carcinoma. CONCLUSIONS: The unexpected alteration in DNA content observed in NUMF epithelia is of great relevance as a biomarker of field cancerized areas.     

Molecular and cellular biomarkers for field cancerization and multistep process in head and neck tumorigenesis

Summary One way to explain the development of head and neck cancer is through the theories of field cancerization, i.e., the exposure of an entire field of tissue to repeated carcinogenic insult, and multistep process, i.e., development of multiple cancers in a predisposed field through a series of recognizable states. Recent molecular genetic studies of histologically normal and prealignant epithelia of high-risk subjects and studies of malignant tumors in aerodigestive tract epithelia have identified a continuum of accumulated specific genetic alterations that possibly occur during the clonal evolution of tumors, namely, during the multistep process. Second primary or multiple primary tumors arise in the same fields as independent clones, with similar but unique molecular genetic and/or cellular alterations. Consequently, the assessment of these genetic and phenotypic alterations has been integrated into clinical chemoprevention trials in an effort to identify biomarkers that are also risk predictors and intermediate end points. This review covers candidate biomarkers of the processes of field cancerization and multistep tumor development in aerodigestive tract epithelia, including general and specific genetic markers, proliferation markers, and squamous differentiation markers.     

Carcinoma-associated fibroblasts: orchestrating the composition of malignancy

The tumor stroma is no longer seen solely as physical support for mutated epithelial cells but as an important modulator and even a driver of tumorigenicity. Within the tumor stromal milieu, heterogeneous populations of fibroblast-like cells, collectively termed carcinoma-associated fibroblasts (CAFs), are key players in the multicellular, stromal-dependent alterations that contribute to malignant initiation and progression. This review focuses on novel insights into the contributions of CAFs to disease progression, emergent events leading to the generation of CAFs, identification of CAF-specific biomarkers predictive of disease outcome, and recent therapeutic approaches aimed at blunting or reverting detrimental protumorigenic phenotypes associated with CAFs.     

Field effect in oral precancer as assessed by DNA flow cytometry and array-CGH

J Oral Pathol Med (2012) 41 : 119–123 Objective: ‘Field cancerization’ is an accepted model for oral carcinogenesis. So far, genetically altered fields have been just reported in the presence of carcinomas. This study assessed the distant mirror fields (MFs) of oral precancer by DNA high‐resolution flow cytometry (hr DNA‐FCM) and array‐Comparative Genomic Hybridization (a‐CGH). Methods: Five leukoplakias without dysplasia (OLs), seven dysplastic leukoplakias (DOLs), and 12 corresponding visually normal and non‐dysplastic MFs were analyzed. DNA aneuploidy (DNA Index, DI ≠ 1) was detected by hr DNA‐FCM on DAPI stained nuclei suspensions. The epithelial DNA aneuploid subclones were FCM‐sorted to obtain genomic DNA for a‐CGH. Results: Mirror fields, OLs, and DOLs showed increasing prevalence of DNA aneuploidy of, respectively, 8%, 20%, and 57%. The average number of chromosome aberrations (Ch‐Abs) was 2.8 in MFs, 3 in OLs, and 10.6 in DOLs. MFs relative to OLs and DOLs had average numbers of Ch‐Abs, respectively, of 1.8 and 3.6. Ch‐Abs were also observed in DNA diploid sublines, and often the same aberrations were observed in both MFs and corresponding OLs/DOLs. Conclusion: DNA aneuploidy and Ch‐Abs in MFs, the last ones being mainly gains, indicate an early onset of field effect in oral carcinogenesis.     

Surgical approach to the management of field cancerization: Own experience

The term field cancerization was proposed by Slaughter in 1953 to describe multifocal neoplastic lesions in the oral mucosa. Currently, it is well known that field cancerization can occur also in the skin. There is no one, universal and generally accepted management for the patients with multiple actinic keratosis and field cancerization. We presented two cases with large field cancerization on the face and the scalp. In both patients, we performed one stage surgery with split thickness skin graft with good final esthetic and functional result. Available literature on the role of classical surgical removal in treating field cancerization is very limited. We believe that surgery can be consider as an option for the treatment in some high risk patients with very large field cancerization, but further observation and evaluation of this method is needed.     

Outer Breast Quadrants Demonstrate Increased Levels of Genomic Instability

Background: Theory holds that the upper outer quadrant of the breast develops more malignancies because of increased tissue volume. This study evaluated genomic patterns of loss of heterozygosity (LOH) and allelic imbalance (AI) in non-neoplastic tissues from quadrants of diseased breasts following mastectomy to characterize relationships between genomic instability and the propensity for tumor development.Methods: Tissues from breast quadrants were collected from 21 patients with various stages of breast carcinoma. DNA was isolated from non-neoplastic tissues using standard methods and 26 chromosomal regions commonly deleted in breast cancer were examined to assess genomic instability.Results: Genomic instability was observed in breast quadrants from patients with ductal carcinomas in situ and advanced carcinomas. Levels of instability by quadrant were not predictive of primary tumor location (P = .363), but outer quadrants demonstrated significantly higher levels of genomic instability than did inner quadrants (P = .017). Marker D8S511 on chromosome 8p22– 21.3, one of the most frequently altered chromosomal regions in breast cancer, showed a significantly higher level of instability (P = .039) in outer compared with inner quadrants.Conclusions: Non-neoplastic breast tissues often harbor genetic changes that can be important to understanding the local breast environment within which cancer develops. Greater genomic instability in outer quadrants can partially explain the propensity for breast cancers to develop there, rather than simple volume-related concepts. Patterns of field cancerization in the breast appear to be complex and are not a simple function of distance from a developing tumor.     

DNA methylation: a marker for carcinogen exposure and cancer risk

Cancers arise as a consequence of multiple genetic and epigenetic alterations. Many genes aberrantly methylated in cancers have been identified in recent years, and their use in cancer diagnosis and therapy is currently under investigation. During our genome-wide screening for a novel tumor-suppressor gene in gastric cancers, we found that only a small amount of aberrant methylation was present, even in non-cancerous gastric mucosae. A subsequent large-scale analysis of the gastric mucosae of healthy individuals and gastric cancer patients using quantitative methylation-specific PCR (qMSP) revealed that Helicobacter pylori infection potently induced aberrant DNA methylation in non-cancerous gastric mucosae and that these high methylation levels can decrease following cessation of the H. pylori infection. Helicobacter pylori infection induced the methylation of specific genes among 48 genes that can be methylated in gastric cancer cell lines. Most importantly, the methylation levels in the gastric mucosae of individuals without H. pylori infection correlated with their risk of gastric cancer. These findings show that a field for cancerization is formed by H. pylori infection and that this field can be measured using DNA methylation as a marker. The concept of an “epigenetic field for cancerization” has been also demonstrated for colon and breast cancers, and it is possibly present for other cancers and other diseases. Applied knowledge of epigenetic changes in human diseases has now started to make an impact on the prevention, diagnostics, and therapeutics of these diseases.     

Genomic patterns of allelic imbalance in disease free tissue adjacent to primary breast carcinomas

Mammary stroma plays an important role in facilitating the neoplastic transformation of epithelial cells, modulating integrity of the extracellular matrix, and maintaining genomic stability, but molecular mechanisms by which stroma affects epithelial structure and function are not well-defined. We used laser-assisted microdissection of paraffin-embedded breast tissues from 30 patients with breast disease and a panel of 52 microsatellite markers defining 26 chromosomal regions to characterize genomic patterns of allelic imbalance (AI) in disease-free tissue adjacent to sites of breast disease and to define genomic regions that may contain genes associated with early carcinogenic processes. The mean frequency of AI in histologically normal tissue adjacent to the primary carcinomas (15.4) was significantly higher than that in distant tissue from the same breast (3.7). The pattern of AI across all chromosomal regions differed between the adjacent tissue and primary tumor in every case. Unique AI events, observed only in tumor (15 of informative markers) or only in adjacent cells (10 of informative markers), were far more common than AI events shared between tumor and adjacent cells (~ 4). Levels of AI characteristic of advanced invasive carcinomas were already present in non-invasive ductal carcinomas in situ, and appreciable levels of AI were observed in adjacent non-neoplastic tissue at all pathological stages. Chromosome 11p15.1 showed significantly higher levels of AI in adjacent cells (p < 0.01), suggesting that this region may harbor genes involved in breast cancer development and progression. Our data indicate that genomic instability may be inherently greater in disease-free tissue close to developing tumors, which may have important implications for defining surgical margins and predicting recurrence.     

茵陈蒿防癌的实验研究

目的：为研究茵陈蒿的防癌作用。方法：研究观察了茵陈蒿水煎剂对亚硝酸钠和N-甲基苄胺诱发的大鼠胃窦及食道上皮的增生性病变的影响。结果：饮用茵陈蒿水煎剂各组有病变的鼠数及病变严重程度均低于阳性对照组，胸腺指数提高，使之恢复到正常水平，且呈剂量依赖性抑制作用。结论：提示茵陈蒿对亚硝酸钠和N-甲基苄胺的诱癌作用有阻断作用，以及增强细胞免疫功能的作用。     

Telomerase activity and survival of late-stage South African esophageal carcinoma patients.

Squamous cell carcinoma of the esophagus is a cancer with a high incidence in South Africa. We have investigated the prognostic value of telomerase activity in tumors as well as nearby normal tissue. Biopsies from 98 patients (71 men and 27 women) were analyzed using an adaptation of the TRAP assay. We found all tumor biopsies to have moderate to high telomerase activity, while one third of biopsies from normal mucosa were negative. The telomerase activity level of the tumors had no prognostic value (P = 0.95) as determined by the log rank test. A P-value of 0.02 was found when the telomerase-negative and moderately positive normal biopsies were grouped together and compared to those with high activity. Our results show that telomerase activity of normal mucosa in the vicinity of the tumor can identify a population of patients with significantly worse prognosis, even in late stage patients.