O1-4-5 - Effects and Functional Mechanisms of Photosan-Loaded Nanoparticle-Mediated Photodynamic Therapy on Ht29 Cells

Abstract

Background: Photodynamic therapy(PDT) is a non-invasive treatment modality for selective destruction of cancer and other diseases.PDT has several potential advantages over surgery and radiotherapy, It requires three elements: a photosensitizer(PS), light and oxygen, Nanoparticles are efficient means to deliver photosensitizers for photodynamic therapy. However, it is largely unknown if Photosan-II can be efficiently delivered by hollow silica nanoparticles (HSNP). We investigated the effects and functional mechanisms of photodynamic therapy (PDT) mediated by a nanocrystallized photosensitizer (Photosan-loaded hollow silica nanoparticles) on the human colon carcinoma cell line HT29.Methods: HT29 cells were treated with nanocrystallized photosensitizer-mediated PDT, and the rate of cell survival and effects on apoptosis or cell necrosis were investigated with tetrazolium (MTT) assays and flow cytometry, respectively. We quantified the variation of Bcl-2 and Bax expression in nude mice transplanted with HT29 cells before and after PDT with quantitative reverse transcription-polymerase chain reaction (qRT-PCR).Results: MTT assays revealed that cell growth was inhibited in an obvious manner, and there was a dramatic decline in the rate of survival (P < 0.05) following PDT; flow cytometry showed predominant induction of apoptosis in PDT-treated cells. qRT-PCR revealed that PDT downregulated Bcl-2 expression with concomitant upregulation of Bax expression in HT29 cells, i.e., the Bcl-2/Bax expression ratio was decreased.Conclusion: PDT mediated by Photosan-loaded hollow silica nanoparticles inhibits the growth of human colon carcinoma HT29 cells with predominant induction of apoptosis. It can also downregulate the Bcl-2/Bax expression ratio, thereby inducing apoptosis in HT29 cells.