Can flow cytometrically determined DNA ploidy and S-phase fraction predict regional metastasis in squamous cell carcinoma of the oral cavity?

Evaluation of cloned cells, animal model, and ATRA sensitivity of human testicular yolk sac tumor

The testicular yolk sac tumor (TYST) is the most common neoplasm originated from germ cells differentiated abnormally, a major part of pediatric malignant testicular tumors. The present study aimed at developing and validating the in vitro and vivo models of TYST and evaluating the sensitivity of TYST to treatments, by cloning human TYST cells and investigating the histology, ultra-structure, growth kinetics and expression of specific proteins of cloned cells. We found biological characteristics of cloned TYST cells were similar to the yolk sac tumor and differentiated from the columnar to glandular-like or goblet cells-like cells. Chromosomes for tumor identification in each passage met nature of the primary tumor. TYST cells were more sensitive to all-trans-retinoic acid which had significantly inhibitory effects on cell proliferation. Cisplatin induced apoptosis of TYST cells through the activation of p53 expression and down-regulation of Bcl- expression. Thus, we believe that cloned TYST cells and the animal model developed here are useful to understand the molecular mechanism of TYST cells and develop potential therapies for human TYST.

S-phase fraction and DNA ploidy in oral leukoplakia

BACKGROUND

The risk of malignant conversion in oral leukoplakia is well documented. Histological findings are often unreliable and it is difficult to predict on the basis of clinical and histopathological changes which leukoplakic lesion will turn malignant.

METHODS

We used the technique of flow cytometry to evaluate the ploidy status, DNA index and S-phase fraction in leukoplakia, oral cancer and normal oral mucosal biopsies and compared it with histological findings. The study was carried out on 30 patients with oral cancer, 60 with leukoplakia and 30 with normal oral mucosal biopsies.

RESULTS

The aneuploidy rate in oral cancers was 64%, for leukoplakia 20%, while all normal mucosal biopsies were diploid. Aneuploid lesions also had a greater S-phase fraction (SPF). The DNA Index (DI) of aneuploid oral cancers was 1.72 and aneuploid leukoplakias was 1.24. Leukoplakia specimens which showed histological evidence of dysplasia had aneuploidy rate of 38%, DI of 1.19 and SPF of 6.2%. The corresponding values for leukoplakia specimens without dysplasia were 14%, 1.09 and 4.1%, respectively.

CONCLUSION

The method of flow cytometry can be used to identify the subset of leukoplakia patients who are at a higher risk of malignant conversion. These patients could undergo more rigid surveillance or undergo excision biopsy of their lesions.

DNA ploidy, proliferative capacity and intratumoral heterogeneity in primary and recurrent head and neck squamous cell carcinomas (HNSCC) – Potential implications for clinical management and treatment decisions

Despite new diagnostic and therapeutic strategies (combined radiochemotherapy, EGFR antibody Cetuximab), the prognosis of head and neck squamous cell carcinoma (HNSCC) is still poor and more information regarding prognosis is essential to establish earlier and better treatment options. To elucidate the role of DNA ploidy and cellular proliferation, resected tumors of 48 patients with primary or recurrent HNSCC were analyzed by flow cytometry and in vitro-5-bromodeoxyuridine incorporation (BrdU). The results were compared with histopathological findings such as tumor size, lymph node involvement and tumor differentiation. To assess the influence of intratumoral heterogeneity of these biological parameters, multiple biopsies (>3) were analyzed by flow cytometry and BrdU-incorporation in 12 larger (>4 cm diameter) tumors. BrdU-labeling index (LI%) was significantly higher in aneuploid HNSCC and correlated significantly with poor histologic differentiation of the analyzed tumor tissues (P<0.001). Furthermore, a trend for higher LI% in nodal positive tumors was observed. Aneuploid HNSCC showed significantly more often tissue dedifferentiation (P=0.049) and in most cases an advanced tumor stage, especially in tumors with biclonal cell lines. Lymph node involvement was also seen more often in aneuploid and undifferentiated tumors. As in aneuploid tumors recurrent HNSCC showed in most cases a higher LI% and poor tissue differentiation, but as a result of the small collection of samples there was no correlation between aneuploidy and tumor recurrence. To proof the robustness of the acquired data and to estimate the influence of intratumoral heterogeneity to ploidy and LI% multiple biopsies were analyzed in larger tumors. Using a specific statistical algorithm a secure estimation of ploidy and LI% was possible by a single biopsy in these tumors. These findings indicate aneuploidy and proliferative activity as important findings for malignant progression in HNSCC. An estimation of these biological parameters may be useful for identification of patients with high risk for lymph node involvement or tumor recurrence and pre-treatment can be performed by a single biopsy. As a conclusion, these patients may benefit from more aggressive treatment.

An oncolytic mutant of herpes simplex virus type-1 in which replication is governed by a promoter/enhancer of human papillomavirus type-16

Although herpes simplex virus type-1 (HSV-1) can be used as an oncolytic virus it has the undesirable side effect of neurotoxicity. To create a virus with improved specificity for oral cancer we used a fragment of human papillomavirus type-16, which is frequently found in oral and cervical cancers, but not elsewhere. The upstream regulatory region, URR16, was shown to have a high level of transcriptional activity in three of four oral cancer cell lines but low activity in three cell lines derived from brain cancers. URR16 was therefore placed in HSV-1, replacing the promoter of the essential gene ICP4, and the resulting virus was named HSPV-1. When cells were infected with HSPV-1, ICP4 was expressed at levels that were not associated with the level of activity of URR16. The virus replicated in each type of cell to a final titer that showed a correlation with the level of expression of ICP4, but with no correlation to either the tumor of origin or the presence of HPV sequences in the cells. To find if some function of HSV-1 was affecting the activity of URR16, oral cancer cells were transfected with a URR-reporter construct and were then infected with virus. This induced transcription, which was attributed to immediate-early viral genes other than ICP4. A promoter/enhancer from a papillomavirus therefore has the potential to regulate the functions of an oncolytic strain of HSV-1, and is affected by functions of both the host cell and of HSV-1 itself.

Heterogeneity, histological features and DNA ploidy in oral carcinoma by image-based analysis

Oral squamous carcinomas appear heterogeneous on DNA ploidy analysis. However, this may be partly a result of sample dilution or the detection limit of techniques. The aim of this study was to determine whether oral squamous carcinomas are heterogeneous for ploidy status using image-based ploidy analysis and to determine whether ploidy status correlates with histological parameters. Multiple samples from 42 oral squamous carcinomas were analysed for DNA ploidy using an image-based system and scored for histological parameters. 22 were uniformly aneuploid, 1 uniformly tetraploid and 3 uniformly diploid. 16 appeared heterogeneous but only 8 appeared to be genuinely heterogeneous when minor ploidy histogram peaks were taken into account. Ploidy was closely related to nuclear pleomorphism but not differentiation. Sample variation, detection limits and diagnostic criteria account for much of the ploidy heterogeneity observed. Confident diagnosis of diploid status in an oral squamous cell carcinoma requires a minimum of 5 samples.

Prognostic relevance of cell proliferation in head and neck tumors

Cell proliferative activity has been extensively investigated in head and neck tumors. Ki67/MIB-1 immunostaining, tritiated thymidine or bromodeoxyuridine labeling indices, DNA S-phase fraction, proliferating cell nuclear antigen expression, potential doubling time and analysis of the nucleolar organizer region associated proteins (AgNORs) have shown significant correlation with prognosis in 4806 cases of tumors of the oral cavity, salivary glands, pharynx and larynx. However, this was not observed in 2968 other reported cases. Discrepancies may depend on various factors: the heterogeneity of the series, which include tumors from various anatomic sites and patients treated with different therapy, and the lack of standardization of methods for assessing cell proliferation. Furthermore, none of the methods currently applied can by themselves define the actual proliferative activity, as it depends both on the proportion of cells committed to the cycle (growth fraction) and the speed of the cell cycle. Indeed, the actual proliferative activity of a tumor could well be measured by the equation [PA = Ki67 or MIB-1 scores x AgNORs], as we did in pharyngeal carcinoma. Provided that large and homogeneous series are evaluated by standardized methods, cell proliferative activity can still be regarded as an inexpensive and reliable prognostic factor in head and neck tumors.