Alterations in Oral Cancer Gene Expression in Response to Melatonin

Aims: Melatonin (MLT) exerts oncostatic effects on numerous tumour types presumably by inhibiting
cell proliferation and promoting apoptosis. The primary aim of this study was to investigate melatonininduced
changes in gene expression patterns in two different oral squamous carcinoma cell lines
(OSCC).
Methodology: This was a prospective non-randomized experimental study design that was
conducted at Department of Biomedical Sciences at the University of Nevada, Las Vegas – School of
Dental Medicine between May 2016 and March 2017. The SCC25 and CAL27 cell lines were cultured
with and without MLT (10 ug/mL) for 72 hours, and total cellular RNA was isolated and converted to
cDNA. The expression of 92 genes associated with the molecular mechanisms of cancer and four
endogenous control genes were examined by qRT-PCR. The fold change with respect to control
levels were calculated using the comparative method or delta-delta ddCt algorithm.
Results: Gene expression was compared between the untreated and treated cells, SCC25 and
CAL27. Although 40% of the genes (n=37/92) in SCC25 cells demonstrated different expression
levels, only six were outside the relative-fold change values observed with all other genes (PTEN,
MAPK3K5, BCL2, TAGA2B, MAX, and NFKB-IA). In CAL27 cell over 70% (n=65/92) genes exhibited
different expression levels, with only two outside the relative fold-change values observed with all
other genes (MAPK3K5, FZD1).
Conclusion: MLT administration to oral cancer cells may induce substantial changes in the
expression levels of genes associated with the molecular mechanisms of cancer. However, relatively
few of these changes were outside the range of observed values. Therefore, continued analysis and
verification of these results in other oral cancers may reveal common MLT-induced changed and
provide insights into the potential mechanisms of MLT-induced oncostatic effects in oral cancers.