Identification of individuals at high risk for head and neck carcinogenesis using chromosome aneuploidy detected by fluorescence in situ hybridization

The effect of environmental chemicals on the tumor microenvironment

Potentially carcinogenic compounds may cause cancer through direct DNA damage or through indirect cellular or physiological effects. To study possible carcinogens, the fields of endocrinology, genetics, epigenetics, medicine, environmental health, toxicology, pharmacology and oncology must be considered. Disruptive chemicals may also contribute to multiple stages of tumor development through effects on the tumor microenvironment. In turn, the tumor microenvironment consists of a complex interaction among blood vessels that feed the tumor, the extracellular matrix that provides structural and biochemical support, signaling molecules that send messages and soluble factors such as cytokines. The tumor microenvironment also consists of many host cellular effectors including multipotent stromal cells/mesenchymal stem cells, fibroblasts, endothelial cell precursors, antigen-presenting cells, lymphocytes and innate immune cells. Carcinogens can influence the tumor microenvironment through effects on epithelial cells, the most common origin of cancer, as well as on stromal cells, extracellular matrix components and immune cells. Here, we review how environmental exposures can perturb the tumor microenvironment. We suggest a role for disrupting chemicals such as nickel chloride, Bisphenol A, butyltins, methylmercury and paraquat as well as more traditional carcinogens, such as radiation, and pharmaceuticals, such as diabetes medications, in the disruption of the tumor microenvironment. Further studies interrogating the role of chemicals and their mixtures in dose-dependent effects on the tumor microenvironment could have important general mechanistic implications for the etiology and prevention of tumorigenesis.

Oral field cancerization: an update on current concepts

There always exists a field with genetically altered cells with a high risk of developing premalignant and malignant lesions. It may often happen that an individual stem cell is genetically altered and can cause the formation of a clone or a patch which is likely to turn into a tumor. This explains the higher recurrence rates following tumor resections. It is essential to identify and to treat this field in order to have greater chances to prevent cancer and achieve a better outcome. This article reports concepts, theories and markers for the assessment of field cancerization.

An overview of the risk factors associated with multiple oral premalignant lesions with a case report of extensive field cancerization in a female patient

BACKGROUND

Field cancerization is a well-known and well-documented process of malignant transformation first coined by Slaughter et al. in 1953. Tobacco chewing was associated with the greatest increase in the risk of multiple oral premalignant lesions and may be the major source of field cancerization of the oral cavity in the Indian population. The field cancerization will probably help clinicians in complementing evaluation of pathologic biopsy specimens.

MATERIAL AND METHODS

We present a case report of field cancerization in a 63-year-old Indian female. She presented with an intra-oral generalized hyperkeratotic verruciform type white lesions involving right and left buccal mucosa, lower labial mucosa, upper and lower vestibule, dorsal, ventral and right lateral border of the tongue, hard and soft palate. Microscopic examination revealed features of verrucous carcinoma in one area, squamous cell carcinoma in another and carcinoma in situ in other areas. Based on the overall features in various areas of the oral cavity, the lesion was diagnosed as field cancerization.

CONCLUSION

Reviewing the literature revealed the presence of a field with genetically altered cells appear to be induced by tobacco (smoking/smokeless form). The large number of premalignant cells in the fields may increase cancer risk considerably. Thus screening and monitoring of the field may have serious implications for oral cancer prevention.

Individual karyotypes at the origins of cervical carcinomas

Background

In 1952 Papanicolaou et al. first diagnosed and graded cervical carcinomas based on individual “abnormal DNA contents” and cellular phenotypes. Surprisingly current papilloma virus and mutation theories of carcinomas do not mention these individualities. The viral theory holds that randomly integrated, defective genomes of papilloma viruses, which are often untranscribed, cause cervical carcinomas with unknown cofactors 20–50 years after infection. Virus-free carcinomas are attributed to mutations of a few tumor-suppressor genes, especially the p53 gene. But the paradox of how a few mutations or latent defective viral DNAs would generate carcinomas with endless individual DNA contents, degrees of malignancies and cellular phenotypes is unsolved. Since speciation predicts individuality, we test here the theory that cancers are autonomous species with individual clonal karyotypes and phenotypes. This theory postulates that carcinogens induce aneuploidy. By unbalancing mitosis genes aneuploidy catalyzes chain reactions of karyotypic evolutions. Most such evolutions end with non-viable karyotypes but a few become new cancer karyotypes. Despite congenitally unbalanced mitosis genes cancer karyotypes are stabilized by clonal selections for cancer-specific autonomy.

Results

To test the prediction of the speciation theory that individual carcinomas have individual clonal karyotypes and phenotypes, we have analyzed here the phenotypes and karyotypes of nine cervical carcinomas. Seven of these contained papilloma virus sequences and two did not. We determined phenotypic individuality and clonality based on the morphology and sociology of carcinoma cells in vitro. Karyotypic individuality and clonality were determined by comparing all chromosomes of 20 karyotypes of carcinomas in three-dimensional arrays. Such arrays list chromosome numbers on the x-axis, chromosome copy numbers on the y-axis and the number of karyotypes arrayed on the z-axis. We found (1) individual clonal karyotypes and phenotypes in all nine carcinomas, but no virus-specific markers, (2) 1-to-1 variations between carcinoma-specific karyotypes and phenotypes, e.g. drug-resistance and cell morphology, (3) proportionality between the copy numbers of chromosomes and the copy numbers of hundreds of over- and under-expressed mRNAs, (4) evidence that tobacco-carcinogens induce cervical carcinomas via aneuploidy, consistent with the speciation theory.

Conclusions

Since the individual clonal karyotypes of nine carcinomas correlated and co-varied 1-to-1 with complex individual transcriptomes and phenotypes, we have classical genetic and functional transcriptomic evidence to conclude that these karyotypes encode carcinomas - much like the clonal karyotypes that encode conventional species. These individual karyotypes explain the individual “DNA contents”, the endless grades of malignancies and the complex individual transcriptomes and phenotypes of carcinomas.

Oral field cancerization: current evidence and future perspectives

INTRODUCTION

Oral field cancerization implies that oral cancer does not arise as an isolated cellular phenomenon but rather as an anaplastic tendency involving many cells at once and results in the multifocal development of cancer at various rates within the entire field in response to a carcinogen especially tobacco. This concept has been frequently used to explain the occurrence of multiple primary cancers and recurrences following complete excision of oral cancer.

DISCUSSION

This review deals in detail with the origin, principle, various theories used to explain this effect and molecular, genetic, as well as cytogenetic findings related to oral field cancerization. Further, the clinical implications and future research directives are also discussed.

Mycotoxin citrinin induced cell cycle G2/M arrest and numerical chromosomal aberration associated with disruption of microtubule formation in human cells

As a nephrotoxic mycotoxin, citrinin (CTN) contaminates various foodstuffs and animal feed commodities. In the present study, the effects of CTN on cell cycle arrest and microtubule formation were investigated by applying human embryonic kidney (HEK293) cells as a model. Exposure of HEK293 cells to CTN resulted in an arrest of cell cycle G2/M in a concentration-dependent increase. Administrating CTN elevated the expression levels of p53 and p21 proteins, yet attenuated the signals of phosphorylated cell division cycle 2 (cdc2). Furthermore, treating HEK293 with CTN increased both the value of mitotic index and the population of cells recognized by antibody mitotic protein monoclonal 2, suggesting that arrest of CTN-induced cell cycle occurred mainly during the mitotic phase. With the assistance of immunocytostaining of α-tubulin, CTN was found to disrupt the stable microtubule skeleton during the interphase of cell cycle and also interfere with the mitotic spindle integrity during mitosis. Additionally, for either in vivo or in vitro assays, CTN effectively inhibited tubulin polymerization in a concentration-dependent manner. When human peripheral blood mononuclear cells were exposed to CTN, the percentage of cells with numerical chromosome changes was increased by 4.3-fold over that of vehicle-treated group. Results of this study suggest that CTN-activated G2/M arrest primarily arises from the inhibition of tubulin polymerization and associated mitotic spindle formation. Additionally, disruption of microtubule organization by CTN also contributes to the induction of numerical chromosome aberration in human cells.

Chromosomal numerical aberrations in apparently normal oral mucosa of heavy smokers affected by lung cancer

Cigarette smoke creates a field of injury in the epithelial lining of the entire respiratory tract causing an increased risk for the development of malignant lesions. It is conceivable, therefore, that early genetic alterations, can be detected in oral mucosa of heavy smokers mainly those affected by lung cancer. As aneuploidy was shown to be an early event in oral carcinogenesis, we aimed to investigate the prevalence of aneuploid cells (ACs) in samples obtained from apparently normal looking oral mucosa of heavy smokers affected by lung cancer (LC). Two brush samples were collected from the oral mucosa of 152 subjects; 31 heavy smokers with LC, 59 heavy smokers without LC and 62 never-smokers. The samples were simultaneously analyzed for morphology and fluorescent in situ hybridization (FISH) using chromosomes 2 and 8 centromeric probes. Over 2% ACs were found in 23% of heavy smokers with LC compared to 12% in heavy smokers without LC and 5% of the never-smokers group (P=0.015). A trend was also noticed when comparing the group of heavy smokers without LC with the never-smokers (P=0.198). We conclude that heavy smokers harbour detectable chromosomal numerical aberrations in oral epithelial cells of normal looking mucosa. These aberrations are more frequently found in heavy smokers affected by LC.

Spectral karyotyping detects chromosome damage in bronchial cells of smokers and patients with cancer

RATIONALE

Lung cancer is a multistep process that is preceded and often accompanied by molecular cytogenetic lesions in benign bronchial epithelium, the precise character, extent and timing of which are not well defined.

OBJECTIVES

In this study we comprehensively defined molecular cytogenetic changes in bronchial cells that may precede lung carcinoma using spectral karyotyping (SKY).

METHODS

SKY was applied to cultured benign bronchial cells from 43 high-risk smokers without carcinoma, 14 patients with concurrent lung carcinoma, and 14 never-smoker healthy volunteers.

MEASUREMENTS AND MAIN RESULTS

The proportion of cells displaying numeric or structural anomalies/total number of metaphase cells was calculated for each case and was referred to as the chromosomal abnormality index. Mean chromosomal abnormality indices were 15.8, 10.1, and 0.7% for patients with cancer, high-risk smokers, and never-smokers, respectively. Clonal abnormalities were found in 17 (40%) of the high-risk smokers without carcinoma and 7 (50%) of the patients with carcinoma, but in none of 14 (0%) never-smokers. Chromosomal gains observed by SKY were confirmed in interphase cultured cells or paraffin sections of biopsy specimens by fluorescence in situ hybridization in 11 of 13 cases for which appropriate probes were available. In 6 of 57 high-risk patients or those with carcinoma, identical clonal abnormalities were dispersed at multiple bronchial sites and were admixed with nonclonal cells.

CONCLUSIONS

Clonal and single-cell chromosomal abnormalities are frequent in benign bronchial epithelium during lung carcinogenesis, indicating that chromosomal missegregation and other chromosomal rearrangements occur before overt malignancy.

Relation of glutathione S-transferase genotypes (GSTM1 and GSTT1) to laryngeal squamous cell carcinoma risk

The purpose of the present study was to investigate GSTM1 and GSTT1 genotypes by using multiplex polymerase chain reaction (PCR) in patients with laryngeal squamous cell carcinoma (LSCC). The genotypes of 110 patients with LSCC and of 197 healthy subjects as the control group were determined by PCR analysis for GSTM1 and GSTT1 genes. Results showed that frequencies of GSTM1-null, GSTT1-null, and both GSTs-null genotypes were 51.8, 30, and 16.4%, respectively, in the patients with LSCC and 37.6, 15.7, and 5.6% in the control group. There was a significant difference between the genotype distributions of all GSTs in patients and in control groups (P < 0.05). The results support the hypothesis that null genotypes of GSTM1 and GSTT1 can reduce detoxification capacity of GSTs as members of the xenobiotic enzyme system. GSTM1-null, GSTT1-null, and both GSTs-null genotypes were more common in the patients with LSCC than in the control group. Patients with both GSTs-null genotypes had the highest risk for supraglottic LSCC in the early period, even if they were light-to-medium smokers. Investigation and determination of the genetic basis of LSCC may contribute to detection of risk groups and to prevent LSCC in the population.

Proteomic analysis reveals successive aberrations in protein expression from healthy mucosa to invasive head and neck cancer

Development of head and neck squamous cell carcinoma (HNSCC) is a multistep process and in many cases involves a phenomenon coined 'field cancerization'. In order to identify changes in protein expression occurring at different stages of tumorigenesis and field cancerization, we analysed 113 HNSCCs and 73 healthy, 99 tumor-distant and 18 tumor-adjacent squamous mucosae by SELDI-TOF-MS on IMAC30 ProteinChip Arrays. Forty-eight protein peaks were differentially expressed between healthy mucosa and HNSCC. Calgizarrin (S100A11), the Cystein proteinase inhibitor Cystatin A, Acyl-CoA-binding protein, Stratifin (14-3-3 sigma), Histone H4, alpha- and beta-Hemoglobin, a C-terminal fragment of beta-hemoglobin and the alpha-defensins 1-3 were identified by mass spectrometry. The alpha-defensins showed various alterations in expression as validated by immunohistochemistry (IHC). Supervised prediction analysis revealed excellent classification of healthy mucosa (94.5% correctly classified) and tumor samples (92.9% correctly classified). Application of this classifier to the tumor-adjacent and tumor-distant mucosa samples disclosed dramatic changes: only 59.6% of the tumor-distant biopsies were classified as normal, 27.3% were predicted as aberrant or HNSCC. Strikingly, 72% of the tumor-adjacent mucosae were predicted as aberrant. These data provide evidence for the existence of genetically altered fields with inconspicuous histology. Comparison of the protein profiles in the tumor-distant-samples with clinical outcome of 32 patients revealed a significant association between aberrant profiles with tumor relapse events (P=0.018; Fisher's exact test, two-tailed). We conclude that proteomic profiling in conjunction with protein identification greatly outperforms histopathological diagnosis and may have significant predictive power for clinical outcome and personalized risk assessment.

HER-2 and cancer antigen 125 evaluation in ovarian borderline tumors by immunohistochemistry and fluorescence in situ hybridization

The study determined the expression of cancer antigen (CA) 125 and HER-2 in 45 borderline ovarian tumors (BOTs) and investigated the correlation of these biologic markers with histologic type, clinical stage, and outcome. The level of CA 125 protein was assessed using DAKO's M-11 clone antibody in immunohistochemistry (IHC) assays (Carpinteria, CA). The HER-2 protein expression was assessed in IHC assays using the HercepTest (DAKO), and the HER-2 gene copy number per cell was investigated through fluorescence in situ hybridization (FISH) assays using VYSIS' PathVysion DNA Probe (Downers Grove, IL). Expression of the CA 125 protein was detected in 49% of the samples (22 out of 45 tumors) and significantly associated with the serous histologic type. However, CA 125 expression did not associate with clinical stage or outcome. Protein overexpression or gene amplification of HER-2 was not found. However, abnormal FISH results were detected in 16% (seven out of 45 patients) of specimens comprising extranumerary copies of HER-2 and/or chromosome 17 per cell. Abnormal FISH results were found to be independent of CA 125 expression and histologic type whereas they positively associate with advanced clinical stage. Our data show that HER-2 is not altered in BOTs, and the presence of aneusomy for chromosome 17 and HER-2 may predict tumor progression.

Analysis of chromosomes 8 and 17 aneuploidies in laryngeal squamous cell carcinoma by fluorescence in situ hybridization

OBJECTIVES/HYPOTHESIS

The objectives were to investigate chromosomes 8 and 17 numerical aberrations by using fluorescence in situ hybridization in laryngeal squamous cell carcinoma and also to determine whether there is any association between chromosomes 8 and 17 aneuploidies and TNM classification and subgroups of laryngeal squamous cell carcinomas.

STUDY DESIGN

Descriptive study.

METHODS

Tumor and control samples were taken from 23 patients with LSCC by surgical operation. Fluorescence in situ hybridization analysis with chromosomes 8- and 17-specific alpha-satellite DNA probes was performed on the interphase nuclei.

RESULTS

The percentages for chromosomes 8 and 17 aneuploidies were 33% (SD = 25.7%) (median value, 26.2%; range, 3.5%-81.8%) and 19.2% (SD = 15.8%) (median value, 9.8%; range, 3.6%-63.7%), respectively. There was a significant difference between stage 2 and stage 3 (P <.05) and between stage 2 and stage 4 for chromosome 8 aneuploidy (P <.05) but not for chromosome 17 aneuploidy (P >.05). There was also a significant difference for the T classification for chromosome 8 aneuploidy (P <.05) but not for chromosome 17 (P >.05).

CONCLUSION

Chromosome 8 aneuploidy may be related to stage and T classification of laryngeal squamous cell carcinoma and its progression.

Numerical aberrations of chromosomes 8, 9, 11, and 17 in squamous cell carcinoma of the pharynx and larynx: a fluorescence in situ hybridization and DNA flow cytometric analysis of 50 cases

Squamous cell carcinoma of the pharynx and larynx (SCCPL) is a genetically complex disease and is frequently associated with nonrandom chromosomal alterations. Fifty primary SCC of the pharynx (oropharynx, n=11): see and hypopharynx, n=11) and larynx ( n=28) were examined for numerical aberrations of chromosomes 8, 9, 11, and 17 with a panel of chromosome-specific repetitive DNA probes by fluorescence in situ hybridization (FISH). DNA ploidy analysis was also performed by flow cytometry (FCM). Aneusomic copy numbers of chromosomes 8, 9, 11, and 17 were discovered in 66%, 68%, 68% and 78% of tumors, respectively. FCM showed abnormal DNA content in 74% of cases (mean DNA index=1.69). Polysomy was the main finding in both DNA-aneuploid and DNA-diploid tumors (64.5% of cases). Numerical aberrations of chromosomes 8 and 11 correlated to DNA ploidy by FCM (P< 0.05). Aneusomy was present in 69.23% of DNA-diploid tumors. Marked intratumoral and intertumoral chromosomal heterogeneity was noted between individual tumors, suggesting a notable heterogeneity in aneuploid and diploid cell populations. Interphase FISH can be used to study important cytogenetic changes which occur during the development of SCC of the pharynx and larynx.

p53-Positive Tumor-Distant Squamous Epithelia of the Head and Neck Reveal Selective Loss of Chromosome 17

OBJECTIVES/HYPOTHESIS

The progression of clinically manifest premalignant lesions in the head and neck region to primary or second primary cancer is characterized by numerical and structural chromosomal aberrations. However, many tumors arise from histologically inconspicuous mucosal sites. The objective was to investigate whether chromosomal aberrations can be detected in tumor-distant mucosa and whether they can help predict the risk of second primary malignancy.

STUDY DESIGN

A retrospective series of 72 clinically healthy, arbitrarily taken mucosal samples from 53 patients with squamous cell carcinoma of the head and neck was studied. A previous analysis of the p53 protein status had revealed both p53-positive and p53-negative samples.

METHODS

The samples were analyzed by fluorescence in situ hybridization (FISH) using centromeric probes specific for the chromosomes 1, 10, 17, and 18.

RESULTS

Tumor-distant mucosa generally showed increased numerical chromosomal aberrations, which consisted mainly of monosomies. In the group of patients with p53-positive epithelia, all aberrations including gains of chromosomes (trisomies, tetrasomies) were more frequent. Monosomy for chromosome 17 was most significantly and selectively enhanced in this group (Wilcoxon Scores [rank sum] test, P =.0002).

CONCLUSION

Detectable chromosomal aberrations occur in clinically healthy epithelia in patients at risk for secondary head and neck cancer. Specifically, unbalanced chromosome 17 monosomy in conjunction with p53 protein overexpression may constitute a valuable biomarker for progressive "field cancerization."

Chromosomal abnormalities in non-small cell lung carcinomas and in bronchial epithelia of high-risk smokers detected by multi-target interphase fluorescence in situ hybridization

Human lung carcinogenesis is accompanied by complex chromosomal changes that may be detected in interphase cells by fluorescence in situ hybridization (FISH) assay using recently developed multitarget DNA probes. Touch preparations of 20 non-small cell lung carcinomas, sputum specimens from 3 patients with lung cancer and from 11 ex-smokers without lung cancer, and cultured benign bronchial epithelium of 42 high-risk smokers, 9 of whom had concurrent invasive carcinoma, were tested using a four-color FISH probe (LAVysion) targeting centromere 6, 5p15.2, 7p12 (EGFR), and 8q24 (MYC). Significantly high frequencies of abnormal cells were found in each of the 20 NSCLC (100%) and in the 3 sputum specimens from lung cancer patients. None of the cytologically normal sputa contained FISH abnormalities. Cultured bronchial epithelial cells from 11 of 42 patients (26%) were abnormal for at least one probe. Abnormal FISH patterns had no association with gender, presence of tumor or histology. Multicolor FISH can readily detect chromosomal abnormalities in imprints and sputa from lung carcinomas. Chromosomal aneusomy is also frequent in bronchial epithelial cells from long-term smokers. The prognostic significance of the multicolor LAVysion FISH probe set should be validated in a controlled clinical trial.

Aneuploidy and cancer

Numeric aberrations in chromosomes, referred to as aneuploidy, is commonly observed in human cancer. Whether aneuploidy is a cause or consequence of cancer has long been debated. Three lines of evidence now make a compelling case for aneuploidy being a discrete chromosome mutation event that contributes to malignant transformation and progression process. First, precise assay of chromosome aneuploidy in several primary tumors with in situ hybridization and comparative genomic hybridization techniques have revealed that specific chromosome aneusomies correlate with distinct tumor phenotypes. Second, aneuploid tumor cell lines and in vitro transformed rodent cells have been reported to display an elevated rate of chromosome instability, thereby indicating that aneuploidy is a dynamic chromosome mutation event associated with transformation of cells. Third, and most important, a number of mitotic genes regulating chromosome segregation have been found mutated in human cancer cells, implicating such mutations in induction of aneuploidy in tumors. Some of these gene mutations, possibly allowing unequal segregations of chromosomes, also cause tumorigenic transformation of cells in vitro. In this review, the recent publications investigating aneuploidy in human cancers, rate of chromosome instability in aneuploidy tumor cells, and genes implicated in regulating chromosome segregation found mutated in cancer cells are discussed.