Alterations in Oral Cancer Gene Expression in Response to Melatonin

Objectives: Melatonin (MLT) exerts oncostatic effects on numerous tumor types presumably by inhibiting cell proliferation and promoting apoptosis. The primary objective of this study was to investigate melatonin-induced changes in gene expression patterns in two different oral squamous carcinoma cell lines (OSCC).

Methods: The OSCC cells SCC-25 and CAL27 were cultured with and without melatonin (10 ug/ml) for 72 hours and total cellular RNA were isolated and converted into cDNA. The expression of 92 genes associated with the molecular mechanisms of cancer and 4 endogenous control genes were examined by qRT-PCR. The fold change with respect to control levels were calculated using the comparative C_T (ΔΔC_T) method.

Results: The expression levels of 92 genes associated with the molecular mechanisms of cancer were compared between the two untreated OSCC cells, SCC-25 and CAL 27. Only 40% of the genes (37/92) demonstrated different expression levels and the fold change in expression was evenly distributed between being higher in the SCC25 cells (19/37) and lower in the SCC25 cells (18/37). In SCC-25 cells, melatonin administration resulted in changes in gene expression of 57 genes (62%) with all but two genes exhibiting higher levels with melatonin treatment. In CAL27 cells, melatonin administration resulted in changes in gene expression of 65 genes (70%) with all of the genes with the exception of one demonstrating higher expression after melatonin treatment.

Conclusions: Melatonin administration to oral cancer cells substantially induces changes in the expression levels of genes associated with the molecular mechanisms of cancer. Continued analysis and verification of the results will likely reveal common melatonin-induced changes and may provide insight into the mechanism of the oncostatic effects of melatonin in oral cancer cells.