Melatonin-Induced Alterations of PAF Signaling Genes in Oral Cancers

Objectives: Platelet-activating factor (PAF) and PAF acetylhydrolase (PAF-AH) play an integral role in the progression and resolution of inflammation but relatively little is known concerning their role in oral squamous cell carcinomas. The primary objective of this study was to investigate the expression levels of PAF receptor (PAF-R) and PAF-AH in response to melatonin administration in three oral squamous carcinoma cell lines (OSCC).

Methods: The OSCC cells SCC-9, SCC-25, and CAL 27 were cultured with and without melatonin (10 ug/ml) for 72 hours and expression levels of PAF-R and PAF-AH were determined by qRT-PCR subsequent to the total RNA isolation and conversion into cDNA.
Results: All three cell lines expressed both PAF-R and PAF-AH, but the amount of gene expression varied between cell lines. Melatonin treatment resulted in an increase of PAF-R gene expression in SCC25 by 40% and in Cal27 by 41% as compared to their respective controls. However, SCC9 had no significant change in PAF-R expression in response to melatonin. Furthermore, melatonin treatment also increased PAF-AH gene expression in SCC25 by 44% and SCC9 by 31% over control levels, but showed no significant difference in Cal27 cells.

Conclusions: We demonstrated that the 3 OSCC cell lines examined have the capacity to respond to PAF and the ability to control PAF levels via the expression of the secreted PAF-AH. Melatonin administration induces changes in PAF signaling gene expression which may contribute to the anti-apoptotic and anti-metastatic effects of melatonin in OSCC cells.