Targeted Photodynamic Therapy: A Novel Approach to Abolition of Human Cancer Stem Cells

Abstract

Cancer is a global burden that has prompted extensive research into prevention and treatment, over many decades. Scientific studies have shown that subset of cells within a tumour, known as cancer stem cells (CSCs), are responsible for tumourigenesis, metastasis, drug resistance, and recurrences. CSCs have characteristic features of enhanced self-renewal, proliferation, and limited but multidirectional differentiation capacity. The discovery of CSCs has initiated extensive research into novel cancer treatment regimes. Evidence indicates that CSCs are resistant to conventional chemo- and radiation therapy leading to treatment failures, cancer metastasis, secondary cancer formation, and relapse. Because of the observed phenomena in the course of cancer prognosis, a need for treatment modalities targeting CSCs is important. Photodynamic therapy (PDT) is a clinically approved, minimally invasive, therapeutic procedure that can exert a selective cytotoxic activity toward cancerous cells while reducing toxicity to normal cells. It uses a photosensitizer (PS) that becomes excited when subjected to light at a specific wavelength, and the PS forms reactive oxygen species (ROS) killing malignant cells. Currently, PDT is being investigated as a target specific treatment for CSCs by the addition of carrier molecules and antibody conjugates bound to the PS. Targeted PDT (TPDT) may be able to not only eradicate the tumour mass but kill CSCs as well.

Phototoxic Potential of Different DNA Intercalators for Skin Cancer Therapy: In Vitro Screening

“…In both paths, ROS with high oxidizing power are generated, leading to cell death through damage to biomolecules [ 7 ]. DNA is among the biomolecules that can be subjected to damage and is the main target for anticancer drugs [ 8 ]. Due to the short lifetime of reactive species, they act essentially at the local level, where they were created, showing the advantage of PDT as a therapy with local action [ 9 ].…”