Distinctive chromosomal instability patterns in oral verrucous and squamous cell carcinomas detected by high-resolution DNA flow cytometry

A novel comparison of Epstein-Barr virus with broad histological spectrum of oral squamous cell carcinoma

Objectives:

To evaluate the immunohistochemical expression of Epstein-Barr virus (EBV) in broad spectrum histological subtypes of oral squamous cell carcinoma (OSCC) and to determine the relationship of EBV with clinicopathological parameters of OSCC.

Methods:

This cross-sectional study included 150 clinically diagnosed OSCC cases from the outpatient of Ziauddin University Hospital from March, 2017 to October, 2018. These were confirmed on histological examination and categorized into conventional squamous cell carcinoma (SCC) and rare variants. Conventional SCC was subcategorized into keratinizing (KSCC), non-keratinizing (NKSCC), and hybrid SCC (HSCC). EBV status was compared among various histological tumor entities and clinicopathological characteristics of OSCC using immunohistochemistry. Chi-square test was used to determine the association of each histological subtype with EBV status with P-value <0.05 considered as statistically significant.

Results:

Conventional tumor was the most frequent squamous cell carcinoma (n=126; 84%). A significant statistical link of EBV infection was observed with rare histological tumors exhibiting acantholysis (P=0.01), as well as tumors involving buccal mucosa (P=0.03), and habitual smokers (P=0.001).

Conclusions:

In this study, acantholytic tumor, a rare histological subtype of OSCC, tended to be EBV related. Moreover, OSCC cases bearing EBV infection were more likely smokers favoring buccal mucosa as primary anatomical site for oral cancer.

Diagnostic Biomarkers in Oral Verrucous Carcinoma: A Systematic Review

Oral verrucous carcinoma (OVC), a low-grade variant of oral squamous cell carcinoma (OSCC), is most frequently seen in the oral cavity. No clear etiology has been found for this lesion, but human papilloma virus, chewing betel nuts, and ultraviolet radiation are suggested as probable causes. Differential diagnosis of OVC is challenging for oral pathologists. The aim of this study was to review the molecular-based approaches for differential diagnosis of OVC. An electronic search was conducted in Medline and Scopus from January 2004 to July 2015 limited to English language publications. Published papers on verrucous carcinoma (VC) were found according to the inclusion and exclusion criteria and analyzed qualitatively. Data extraction were performed according to PRISMA statement. A total of 423 articles were reviewed; out of which, 26 articles completely fulfilled the inclusion criteria. Most of the included studies investigated proliferative and apoptotic biomarkers such as p53 and Ki67. No definite conclusion was drawn for cytoskeletal biomarkers due to variability of factors and lack of significant expression. However, it seems that cytokeratin10 (CK 10) can be useful for differentiation of OVC and benign squamous lesions. Among cell surface and extracellular matrix biomarkers tissue biomarkers, matrix metalloproteinase (MMP)-2, -9, CD31 and CD68 seem to be useful for differentiation of OVC and OSCC and glucose transporter-1 (GLUT-1) can help in differentiation of OVC from oral epithelial dysplasia. Differences among OVC, OSCC and normal epithelium in expression profiles of the investigated biomarkers help in their differential diagnosis; although, clinicohistopathological similarities among verrucous hyperplasia, noninvasive OVC and invasive well-differentiated OSCC make the diagnosis difficult. Further studies are required to better differentiate these oral lesions.

Oral verrucous carcinoma: From multifactorial etiology to diverse treatment regimens (Review)

Oral verrucous carcinoma (OVC) is a verrucous variant of oral squamous cell carcinoma (OSCC), which accounts for 2-12% of all oral carcinomas with a 5-year survival rate of only approximately 50%. Enormous effort has been dedicated to this cancer, and the past decades have witnessed significant advances in relevant diagnostic and therapeutic approaches. Currently, there exist three challenges from primary sub-fields of research and clinical practice of the cancer, namely multifactorial etiology, complex molecular mechanism, and deficient treatment. This study reviews the existing literature on the cancer, encompassing its etiology, clinical manifestations and pathology, molecular mechanism, diagnosis and differential diagnosis, and treatment. For improved treatment of OVC, multifactorial etiology analysis, incorporation of effective biomarkers for mechanism illustration, and integration of multidisciplinary modalities are expounded, in an attempt to resolve the challenges and to provide a useful guide for future research in the field.

A novel genomic signature reclassifies an oral cancer subtype

Verrucous carcinoma of the oral cavity (OVC) is considered a subtype of classical oral squamous cell carcinoma (OSCC). Diagnosis is problematic, and additional biomarkers are needed to better stratify patients. To investigate their molecular signature, we performed low-coverage copy number (CN) sequencing on 57 OVC and exome and RNA sequencing on a subset of these and compared the data to the same OSCC parameters. CN results showed that OVC lacked any of the classical OSCC patterns such as gain of 3q and loss of 3p and demonstrated considerably fewer genomic rearrangements compared to the OSCC cohort. OVC and OSCC samples could be clearly differentiated. Exome sequencing showed that OVC samples lacked mutations in genes commonly associated with OSCC (TP53, NOTCH1, NOTCH2, CDKN2A and FAT1). RNA sequencing identified genes that were differentially expressed between the groups. In silico functional analysis showed that the mutated and differentially expressed genes in OVC samples were involved in cell adhesion and keratinocyte proliferation, while those in the OSCC cohort were enriched for cell death and apoptosis pathways. This is the largest and most detailed genomic and transcriptomic analysis yet performed on this tumour type, which, as an example of non-metastatic cancer, may shed light on the nature of metastases. These three independent investigations consistently show substantial differences between the cohorts. Taken together, they lead to the conclusion that OVC is not a subtype of OSCC, but should be classified as a distinct entity.

Investigation of epothilone B-induced cell death mechanisms in human epithelial cancer cells -in consideration of combined treatment with ionizing radiation

Epothilone B was shown to have promising chemo- and radiosensitizing effects on cells, but the mechanisms underlying cell death remain ambiguous. The aim of the study was to examine selected cell death pathways on the basis of FaDu and A549 cells. Western blot analyses were used for investigation of specific apoptotic markers. Immunofluorescence imaging and flow cytometry were utilized for examination of cell death mechanisms. DNA-staining was used for studying influence of epothilone B on micronucleus rate. We showed that epothilone B can initiate cell death via apoptosis and mitotic catastrophe, but induction of cell death was cell type specific.

Oral proliferative verrucous leucoplakia: are there particular features for such an ambiguous entity? A systematic review

Proliferative verrucous leucoplakia (PVL) is a distinct, particularly aggressive form of oral leucoplakia. Given the low prevalence of PVL, data are sparse and are mostly from case reports, case series and only a few case-control studies, meaning that the literature is able to provide only weak evidence. The present systematic literature review aims to collate the available evidence on the following issues: patient demographics, aetiology, lesion location(s), malignant potential, location and histopathological features of transformed lesions, disease-specific survival rates and treatment response. Electronic databases were searched for studies in the English language reporting original data from at least 10 patients with PVL on the target issues of the present review. The retrieved data were merged and a descriptive analysis performed. The 20 studies selected indicated that PVL does not seem to be correlated with the major risk factors for oral carcinoma (tobacco, alcohol and/or areca nut/betel leaf chewing). The disorder affects mainly adult/elderly women and has a very high malignant transformation rate, particular site distribution and particular location and histopathological features of transformed lesions. The present results may be limited by some articles being unintentionally excluded as they were not found during the electronic search, a lack of worldwide accepted diagnostic criteria for PVL, and overlapping data from multiple studies performed in a limited number of centres. Despite these potential drawbacks, the present results demonstrate that PVL does have particular features.

Intratumour diversity of chromosome copy numbers in neuroblastoma mediated by on-going chromosome loss from a polyploid state

Neuroblastomas (NBs) are tumours of the sympathetic nervous system accounting for 8–10% of paediatric cancers. NBs exhibit extensive intertumour genetic heterogeneity, but their extent of intratumour genetic diversity has remained unexplored. We aimed to assess intratumour genetic variation in NBs with a focus on whole chromosome changes and their underlying mechanism. Allelic ratios obtained by SNP-array data from 30 aneuploid primary NBs and NB cell lines were used to quantify the size of clones harbouring specific genomic imbalances. In 13 cases, this was supplemented by fluorescence in situ hybridisation to assess copy number diversity in detail. Computer simulations of different mitotic segregation errors, single cell cloning, analysis of mitotic figures, and time lapse imaging of dividing NB cells were used to infer the most likely mechanism behind intratumour variation in chromosome number. Combined SNP array and FISH analyses showed that all cases exhibited higher inter-cellular copy number variation than non-neoplastic control tissue, with up to 75% of tumour cells showing non-modal chromosome copy numbers. Comparisons of copy number profiles, resulting from simulations of different segregation errors to genomic profiles of 120 NBs indicated that loss of chromosomes from a tetraploid state was more likely than other mechanisms to explain numerical aberrations in NB. This was supported by a high frequency of lagging chromosomes at anaphase and polyploidisation events in growing NB cells. The dynamic nature of numerical aberrations was corroborated further by detecting substantial copy number diversity in cell populations grown from single NB cells. We conclude that aneuploid NBs typically show extensive intratumour chromosome copy number diversity, and that this phenomenon is most likely explained by continuous loss of chromosomes from a polyploid state.

Effect of epothilone B on cell cycle, metabolic activity, and apoptosis induction on human epithelial cancer cells-under special attention of combined treatment with ionizing radiation

In recent studies, epothilone B was shown to have a cytotoxic and radiosensitizing effect on cells. The aim of our investigation was to explain this impact by examining the mode of action of epothilone B on FaDu and A549 tumor cells. Flow cytometry was used for cell cycle distribution and for the evaluation of apoptosis. Metabolic activity was studied by proliferation assay. Influence on nuclei morphology was investigated by DNA-staining. We showed that epothilone B-induced G2/M accumulation is the main rationale for drug-induced radiosensitivity. The cytotoxic effect resulted in apoptotic cell death, decreased metabolic activity, and formation of multinucleated cells.

Radiosensitizing effect of epothilone B on human epithelial cancer cells

BACKGROUND

A combined modality treatment employing radiation and chemotherapy plays a central role in the management of solid tumors. In our study, we examined the cytotoxic and radiosensitive effect of the microtubule stabilizer epothilone B on two human epithelial tumor cell lines in vitro and its influence on the microtubule assembly.

METHODS

Cancer cells were treated with epothilone B in proliferation assays and in combination with radiation in colony-forming assays. For the analysis of ionizing radiation-induced DNA damage and the influence of the drug on its repair a γH2AX foci assay was used. To determine the effect of epothilone B on the microtubule assembly in cells and on purified tubulin, immunofluorescence staining and tubulin polymerization assay, respectively, were conducted.

RESULTS

Epothilone B induced a concentration- and application-dependent antiproliferative effect on the cells, with IC(50) values in the low nanomolar range. Colony forming assays showed a synergistic radiosensitive effect on both cell lines which was dependent on incubation time and applied concentration of epothilone B. The γH2AX assays demonstrated that ionizing radiation combined with the drug resulted in a concentration-dependent increase in the number of double-strand breaks and suggested a reduction in DNA repair capacity. Epothilone B produced enhanced microtubule bundling and abnormal spindle formation as revealed by immunofluorescence microscopy and caused microtubule formation from purified tubulin.

CONCLUSION

The results of this study showed that epothilone B displays cytotoxic antitumor activity at low nanomolar concentrations and also enhances the radiation response in the tumor cells tested; this may be induced by a reduced DNA repair capacity triggered by epothilone B. It was also demonstrated that epothilone B in fact targets microtubules in a more effective manner than paclitaxel.