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Discovering drug candidates for the modulation of metastasis is of great importance in inhibiting oral cancer malignancy. Although most pomegranate extract applications aim at the antiproliferation of cancer cells, its antimetastatic effects remain unclear, especially for oral cancer cells. The aim of this study is to evaluate the change of two main metastasis characters, migration and invasion of oral cancer cells. Further, we want to explore the molecular mechanisms of action of pomegranate extract (POMx) at low cytotoxic concentration. We found that POMx ranged from 0 to 50 μg/mL showing low cytotoxicity to oral cancer cells. In the case of oral cancer HSC-3 and Ca9-22 cells, POMx inhibits wound healing migration, transwell migration, and matrix gel invasion. Mechanistically, POMx downregulates matrix metalloproteinase (MMP)-2 and MMP-9 activities and expressions as well as epithelial-mesenchymal transition (EMT) signaling. POMx upregulates extracellular signal-regulated kinases 1/2 (ERK1/2), but not c-Jun N-terminal kinase (JNK) and p38 expression. Addition of ERK1/2 inhibitor (PD98059) significantly recovered the POMx-suppressed transwell migration and MMP-2/-9 activities in HSC-3 cells. Taken together, these findings suggest to further test low cytotoxic concentrations of POMx as a potential antimetastatic therapy against oral cancer cells.

Oral cancer is the sixth most common cancer worldwide with a high mortality rate. Biomarkers that anticipate susceptibility, prognosis, or response to treatments are much needed. Oral cancer is a polygenic disease involving complex interactions among genetic and environmental factors, which require multifaceted analyses. Here, we examined in a dataset of 103 oral cancer cases and 98 controls from Taiwan the association between oral cancer risk and the DNA repair genes X-ray repair cross-complementing group (XRCCs) 1-4, and the environmental factors of smoking, alcohol drinking, and betel quid (BQ) chewing. We employed logistic regression, multifactor dimensionality reduction (MDR), and hierarchical interaction graphs for analyzing gene-gene (G×G) and gene-environment (G×E) interactions. We identified a significantly elevated risk of the XRCC2 rs2040639 heterozygous variant among smokers [adjusted odds ratio (OR) 3.7, 95% confidence interval (CI)=1.1-12.1] and alcohol drinkers [adjusted OR=5.7, 95% CI=1.4-23.2]. The best two-factor based G×G interaction of oral cancer included the XRCC1 rs1799782 and XRCC2 rs2040639 [OR=3.13, 95% CI=1.66-6.13]. For the G×E interaction, the estimated OR of oral cancer for two (drinking-BQ chewing), three (XRCC1-XRCC2-BQ chewing), four (XRCC1-XRCC2-age-BQ chewing), and five factors (XRCC1-XRCC2-age-drinking-BQ chewing) were 32.9 [95% CI=14.1-76.9], 31.0 [95% CI=14.0-64.7], 49.8 [95% CI=21.0-117.7] and 82.9 [95% CI=31.0-221.5], respectively. Taken together, the genotypes of XRCC1 rs1799782 and XRCC2 rs2040639 DNA repair genes appear to be significantly associated with oral cancer. These were enhanced by exposure to certain environmental factors. The observations presented here warrant further research in larger study samples to examine their relevance for routine clinical care in oncology.