Analysis of DNA ploidy using fresh frozen tissues of head and neck squamous cell carcinomas

Comparison of cisplatin sensitivity and the 18F fluoro-2-deoxy 2 glucose uptake with proliferation parameters and gene expression in squamous cell carcinoma cell lines of the head and neck

Background

The survival of patients with locally advanced head and neck cancer is still poor, with 5-year survival rates of 24–35%. The identification of prognostic and predictive markers at the molecular and cellular level could make it possible to find new therapeutic targets and provide "taylor made" treatments. Established cell lines of human squamous cell carcinoma (HNSCC) are valuable models for identifying such markers.

The aim of this study was to establish and characterize a series of cell lines and to compare the cisplatin sensitivity and 18F fluoro-2 deoxy 2 glucose (18F-FDG) uptake of these cell lines with other cellular characteristics, such as proliferation parameters and TP53 and CCND1 status.

Methods

Explant cultures of fresh tumour tissue were cultivated, and six new permanent cell lines were established from 18 HNSCC cases. Successfully grown cell lines were analysed regarding clinical parameters, histological grade, karyotype, DNA ploidy, and index and S-phase fraction (Spf). The cell lines were further characterized with regard to their uptake of 18F-FDG, their sensitivity to cisplatin, as measured by a viability test (crystal violet), and their TP53 and CCND1 status, by fluorescence in situ hybridization (FISH), polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) with DNA sequencing and, for cyclin D1, by immunohistochemistry.

Results

Patients with tumours that could be cultured in vitro had shorter disease-free periods and overall survival time than those whose tumours did not grow in vitro, when analysed with the Kaplan-Meier method and the log-rank test. Their tumours also showed more complex karyotypes than tumours from which cell lines could not be established. No correlation was found between TP53 or CCND1 status and 18F-FDG uptake or cisplatin sensitivity. However, there was an inverse correlation between tumour cell doubling time and 18F-FDG uptake.

Conclusion

In vitro growth of HNSCC cells seem to be an independent prognostic factor, with cell lines being more readily established from aggressive tumours, a phenomenon more dependent on the molecular genetic characteristics of the tumour cells than on tumour location or TNM status.

Surfing prognostic factors in head and neck cancer at the millennium

The ability to reliably predict cancer outcome could tailor therapy to the aggressiveness of the tumour to achieve the best results in terms of loco-regional control, overall survival and quality of life. Retrospective and prospective clinical trials involving large series of patients have validated some predictive clinical and pathological factors, whereas the utility of many other prognostic factors has not been established. This has led to some confusion in clinical practice. In order to clarify the significance, role and cost of these prognostic factors we carried out a Medline search of all papers published between 1993 and 1998 concerning the reliability and cost of markers with prognostic significance, in head and neck squamous cell carcinoma, and assessed the results according to a number of criteria relating to reliability and cost. Regarding reliability we classified prognostic factors into: (1) those with a proven significance based on the fact that they were unanimously reported as having an independent statistical correlation with outcome and prognosis; and (2) those for which results were not unanimous, and which significance is still controversial. Cost analysis showed a substantial difference between validated tests which are of low cost and experimental tests which are expensive. Based on these data regarding both the reliability and cost of each prognostic factor, we propose guidelines for their use in clinical practice in the year 2000.