Anti-tumor photodynamic therapy (PDT) is a unique oxidative stress-based modality that has proven highly effective on a variety of solid malignancies.PDT is minimally invasive and generates cytotoxic oxidants such as singlet molecular oxygen (1O2).With high tumor site-specificity and limited off-target negative effects, PDT is increasingly seen as an attractive alternative or follow-up to radiotherapy or chemotherapy.Nitric oxide (NO) is a short-lived bioactive free radical molecule that is exploited by many malignant tumors to promote cell survival, proliferation, and Coil Set metastatic expansion.
Typically generated endogenously by inducible nitric oxide synthase (iNOS/NOS2), low level NO can also antagonize many therapeutic interventions, including PDT.In addition to elevating resistance, iNOS-derived NO can stimulate growth and migratory aggressiveness of tumor cells that survive a PDT challenge.Moreover, NO from PDT-targeted cells Kids Footwear in any given population is known to promote such aggressiveness in non-targeted counterparts (bystanders).Each of these negative responses to PDT and their possible underlying mechanisms will be discussed in this chapter.
Promising pharmacologic approaches for mitigating these NO-mediated responses will also be discussed.