Possible Mechanisms of Resistance Development to Photodynamic Therapy (PDT) In Vulvar Cancer Cells

Abstract

Photodynamic therapy (PDT) is a low-invasive treatment method that can be used to treat VIN patients. A photosensitizer (PS) applied to a patient is activated with use of the appropriate wavelength of light, which in an oxygen environment leads to the formation of a reactive oxygen species (ROS) that destroys the tumor. However, cells can protect themselves against these cytotoxic products by increasing their antioxidant mechanisms and repair capacity. Changes in the cytoskeleton may also influence resistance to PDT. Our results revealed that PDT-resistant cells changed the amount of ROS. Cells resistant to PDT A-431 exhibited a decreased ROS level and showed higher viability after oxidizing agent treatment. Resistant Cal-39 cells exhibited a decreased O2− level but increased other ROS. This provides protection from PDT but not from other oxidizing agents. Moreover, PDT leads to alterations in the cytoskeleton that may result in an epithelial-mesenchymal transition (EMT) or increased adhesion. Both EMT and cell adhesion may activate signaling pathways involved in survival. This means that resistance to PDT in vulvar cancer may be at least in part a result of changes in ROS level and alterations in the cytoskeleton.

Increased CD56 expression after photodynamic therapy indicates an increased natural killer cell count following early photodynamic therapy for cutaneous squamous cell carcinoma

“…In the present study, the patients with cSCC showed no difference in T cell number after PDT within 24 h, which seems to be a contradicting result. Studies have shown that PDT may trigger immune responses that contribute to its therapeutic effectiveness ( 26 , 27 ). PDT is linked to several important immunological effects.…”

Nanomaterial-related hemoglobin-based oxygen carriers, with emphasis on liposome and nano-capsules, for biomedical applications: current status and future perspectives

“…Photodynamic therapy (PDT), a clinically recognized and minimally invasive tumor treatment, has become an alternative to chemotherapy [ 182 , 183 ]. PDT includes a photosensitizer (PS), a light source, and sufficient O 2 .…”

Antioxidant and Cytotoxic Activity of New Polyphenolic Derivatives of Quinazolin-4(3H)-one: Synthesis and In Vitro Activities Evaluation

“…Healthy cells, thereby subjected to chronic oxidative stress, can be transformed into cancer cells, through the mechanism presented above. Tumor cell survival, proliferation, chemoresistance, radioresistance, invasion, angiogenesis and stem cell survival are caused in the same way [ 11 , 13 , 14 , 15 ].…”