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Background/purpose 5-Aminolevulinic acid mediated photodynamic therapy (ALA-PDT) has been used for the treatment of precancerous lesions and oral cancers. Compared with traditional treatment such as surgery, ALA-PDT can selectively kill cancer cells and reduce side effects. However, some cells might survive from PDT and may be directly attributable to the limited penetration of light. Therefore, it is necessary to elucidate alterations in cellular behavior and molecular mechanisms in cancer cells that have survived from PDT. Materials and methods Human tongue squamous carcinoma cells, SCC-4 cells, and mice bearing C26 tumors were used as cancer models in vitro and in vivo . After irradiation with the LD 50 (50% lethal dose) light dose, the ability of cellular migration and metastasis related gene expression were assayed. Results Cells were rounded up and migration ability was shown to have significantly decreased under the influence of irradiation with the LD 50 light dose. Gene expression related to metastasis including matrix metalloproteinases (MMPs) and chloride intracellular channel 4 (CLIC4) was also reduced. In addition, in the animal tumor model, mRNA expression of MMP9 and CLIC4 was also noticeably decreased. Conclusion Our results indicate that PDT could reduce the expression of invasion related genes of surviving cancer cells in vitro as well as in vivo . These could be used as references for clinical PDT of oral cancer in the future.

The objective of this study is to explore the relationship between migration ability and invadosome organization in human oral squamous cancer cells. Wound healing assay, immunofluorescence, Western blotting, and matrix metalloproteinase zymogen gel assay were utilized to investigate the phenotype changes of three oral squamous cancer cells (OC3, OC3-I5, and OC3-IV2). Among these three cell lines, selective subpopulations of OC3, OC3-I5, and OC3-IV2 have high migratory ability compared to OC3 in a wound healing assay. Moreover, immunofluorescence showed that formation of actin dots and paxillin rings in OC3 was less than in OC3-I5 and OC3-IV2. Minor differences of other adhesion molecules and matrix metalloproteinase activity have also been observed. Enhanced cell migration ability and increased invadosomes have been detected in both in vitro selection cell line OC3-I5 and in vivo selection cell line OC3-IV2, suggesting that there may be a correlation between migration activity and invadosome formation in invasive oral cancer cells. Therefore, it would be interesting for us to continue discovering more invadosome components and evaluate whether they play any role in the regulation of the invasion ability of oral cancer cells.