Photodynamic Effects of Vitamin K3 on Cervical Carcinoma Cells Activating Mitochondrial Apoptosis Pathways

Abstract

Background: Photodynamic Therapy (PDT) is a photoactivation or photosensitization process, wherein vitamin K3 (Vit K3) serves as a photosensitizer to produce Reactive Oxygen Species (ROS) against bacteria at appropriate wavelengths. In this study, we used Vit K3 treatment combined with Ultraviolet radiation A (UVA) to produce photodynamic effects on cervical cancer.

Methods: The dose-concentration relationship between Vit K3 treatment and UVA on tumor cells was analyzed through the Cell Counting Kit-8 method. Then, the morphological characteristics of apoptosis cells were observed through fluorescent staining and fluorescence microscopy. Apoptosis after treatment with Vit K3 treatment, UVA, and Vit K3 treatment plus UVA was further observed through Western blot analysis, flow cytometry, and TUNEL assay. The xenograft models from HeLa cells were established for the exploration of the photodynamic effect of Vit K3 treatment on cervical cancer in vivo.

Results: Vit K3 treatment plus UVA reduced tumor cell viability in a dose-dependent manner. Further studies indicated that Vit K3 treatment plus UVA can inhibit tumor growth and enhance the apoptosis of cervical cancer cells. In the combination group, the expression levels of cleaved caspase-3, cleaved caspase-9, B-cell lymphoma- extra large (Bcl-xl), and cytochrome c (cyt-c) increased obviously, whereas the expression level of Bcell lymphoma 2 (Bcl-2) decreased relative to the expression levels of UVA- or Vit K3-treated cells. In the in vivo experiments, tumor growth was inhibited significantly in the VitK3 treatment plus UVA group. Additionally, we demonstrated that the combination therapy mediated an increase in cleaved caspase-3 and cleaved caspase-9 expression and decrease in Bcl-2 expression in vivo.

Conclusion: Our results showed that Vit K3 treatment combined with UVA exerted photodynamic effects on cervical cancer cells by activating mitochondrial apoptosis pathways.

Keywords: Vitamin K3; apoptosis; caspase-9; cervical cancer; photodynamic therapy; photosensitizer.