The areca nut is a known
carcinogen that causes
oral cancer in individuals in Southeast Asia, but the molecular mechanism that leads to this
malignancy is still unclear. To mimic the habit of areca nut chewing, our laboratory has established four
oral cancer cell sublines (SAS, OECM1, K2, C9), which have been chronically exposed to areca nut extract (ANE). To elucidate the molecular basis of areca nut-induced oral
carcinogenesis, the differential
proteomes between
oral cancer cells and the ANE-treated sublines were determined using isobaric mass tag (iTRAQ) labeling and multidimensional liquid chromatography-mass spectrometry (LC-MS/MS). Over 1000
proteins were identified in four sublines, and 196
proteins were found to be differentially expressed in at least two ANE-treated sublines. A bioinformatic analysis revealed that these
proteins participate in several pathways, and one of the most prominent pathways was the regulation of epithelial to mesenchymal transition (EMT). In all, 24
proteins including Krt17 were confirmed to be differentially expressed in the ANE-treated sublines. To reveal additional information on the mechanism of ANE-induced
carcinogenesis, Krt17 was further investigated. Krt17 knockdown significantly suppressed ANE-induced cell migration and invasion and modulated the EMT process. Furthermore, in a murine model of
carcinogen-induced (
arecoline cocktail, an active compound of ANE)
oral cancer, Krt17 was significantly up-regulated in all hyperplastic tissues and in
carcinoma tissues (p < 0.001). In conclusion, we have identified a
proteome of
oral cancer cells that is associated with chronic areca nut exposure. Krt17 was demonstrated to contribute to areca nut-induced oral
malignancy. The results of this study contribute to risk assessment, disease prevention and other clinical applications associated with areca nut-induced
oral cancer.