Potential therapeutic efficacy of Photodynamic Therapy on triple negative breast cancer in hormonal microenvironment

There are seldom studies on the determination of cancer treatment efficacy related to normal hormonal tumor microenvironment on triple negative breast cancer (TNBC). This study aimed to determine Hexyl-ALA-PDT efficacy on TNBC in a simulated hormonal microenvironment. The 3D spheroids of TNBC cells (MDA-MB-231) were generated in the hormonal supplemented microenvironment. The accumulation of PpIX, phototoxicity, the ROS level and p-ULK1 expression level mediated by Hexyl-ALA-PDT were determined by confocal microscopy, MTT assay and flow cytometry. A lower Hexyl-ALA concentration was required to achieve the same lethal dose of LD50 with hormonal supplement in 3D spheroids. It was found that the ROS level was increased at lower Hexyl-ALA-PDT dose in hormonal microenvironment, which also correlated the decrease of p-ULK1 expression by PDT. Hexyl-ALA-PDT increased ROS level in TNBC in hormonal microenvironment; and with the reduced p-ULK1 expression thus indicating autophagy of cell death might be triggered.