The Study on Chlorhexidine Digluconate in Enhancing the Cytotoxic Effect of 5-ALA Photodynamic Therapy on Oral Cancer Cells with Variant Resistance

Autor: Jan Michael Silvosa Antes, 安明克
Rok vydání: 2019
Druh dokumentu: 學位論文 ; thesis
Popis: 107
Introduction: Photodynamic therapy (PDT) is a minimally invasive treatment for oral premalignant lesions and early cancers. However, one of the drawbacks of PDT is the formation of resistant cancer cells from multiple treatments. The mechanism that provides oral cancer cells protection from the cytotoxic effects of PDT could be from the overexpression of the Bcl-2 protein that regulates the apoptosis of the cells. Objective: This paper demonstrates the acquired resistance of the cells to PDT with subsequent increase of Bcl-2 expression from multiple exposures. The use of Chlorhexidine digluconate (CHX) could alter the Bcl-2 expression resulting in sensitizing these resistant cells again to the effects of PDT. Multiple exposures of CHX to the parental oral cancer cells were also performed to further explore its effects when used in conjunction with multiple treatments of PDT in the clinical setting. Materials and Methods: Cultured PDT-resistant SAS and Ca9-22 cells were established through multiple LD50 exposures of PDT. These cells were treated with determined LD50 concentration of CHX for 30s and then were treated with PDT. MTT assay was performed to compare the cell viability of each treatment conditions (PDT-alone, CHX-alone, and Combination PDT and CHX). The ratio of Bcl-2/Bax expression was also compared between pre- and post-exposures of CHX on parental and resistant cell lines through Western blot assay. Parental cells of SAS and Ca9-22 were also exposed to multiple CHX treatments. Subsequently, the protein expression of EMT markers E-cadherin and Vimentin were detected through Western blot Assay and migration ability through transwell assay. Result: It has been shown that the combination of CHX and PDT had a synergistic effect on the killing of cancer cells and their resistant strains. The mechanism involved may be due to the inhibitory interaction of CHX to the Bcl-2 proteins. We also found out that multiple exposures to CHX could also yield resistance to the antiseptic and even induce EMT phenomenon on oral SAS cells. However, although EMT was noted, the migration rate of these post-EMT SAS cells was paradoxically decreased. Likewise, the migration ability was also observed to have decreased in multiple CHX-exposed Ca9-22 cells, though no EMT phenomenon was noted. Conclusion: The findings show the advantage of CHX that not only it could be used as an adjunct treatment to deal with PDT-resistant oral cancer lesions but also aid in the localization of the lesion and inhibition of any metastatic effect. However, further studies are needed to elucidate the CHX-induced EMT and its consequent resistance on SAS cells.
Databáze: Networked Digital Library of Theses & Dissertations
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