Correlation of metallothionein expression with clinical progression of cancer in the oral cavity

Abstract

This study aimed at finding out whether the expression of metallothionein (MT), laminin, Ki-67 antigen and minichromosome maintenance-2 (Mcm-2) protein changes with growing invasiveness of the tumour. The expression of these markers in primary tumours with no metastases to lymph nodes (PT N-) was compared with the expression in primary tumours with metastases in draining lymph nodes (PT N+). The difference in marker expression was also evaluated between metastatic lymph nodes (LN+) and the corresponding primary tumours (PT N+).

Patients and methods: The studies were performed on tumour samples from 39 patients with squamous cell carcinoma of the oral cavity floor or of the oral part of the tongue. All the patients had been subjected to radical surgery, accompanied by the removal of lymph nodes. In 20 patients post-operative histopathology disclosed the presence of metastases in the draining lymph nodes (pN+), while in 19 patients the presence of such metastases was excluded (pN0).

Results: The PT N+ group was found to contain a significantly higher percentage of cells with cytoplasmic expression of MT, than the PT N- group. In turn, a significant increase in the intensity of reaction of cytoplasmic MT and an increased percentage of cancer cells demonstrating MT expression in the cell nuclei was demonstrated in the LN+ compared to the PT N+ group. The expression of the remaining parameters did not significantly differ between PT N-, PT N+ and LN+.

Conclusion: A gradual increase in MT expression (both cytoplasmic and nuclear) takes place with progression of the tumour and the increased nuclear expression of MT in LN+ cells may suggest a role of MT in metastasis development in the studied tumours.