Dr. Stefan Bossmann's laboratory
The quintessential cancer treatment would target only the cancer cells and leave the healthy alone, minimizing the negative effects of treatment. Photodynamic Therapy (PDT) is known to target tumor tissue selectively, but classic PDT methods are dependent on the availability of oxygen. The ideal PDT agent is strictly non-toxic in the dark, and when irradiated, becomes very toxic. Furthermore, PDT often causes apoptosis (programmed cell death) rather than necrosis of the cancerous tissue. The advantage of the former is that healthy human tissue is not affected by the treatment procedure, whereas the latter is often the cause for serious complications such as inflammation and allergic shock reactions. Unfortunately, malignant and especially drug-resistant cells are often hypoxic (very low in oxygen content) and thus render PDT useless. A special class of ruthenium-complexes, which are good PDT-agents because they can cut DNA under irradiation even in the absence of oxygen, could be the answer to this PDT problem, provided they can be introduced into the cancer cells. The porins isolated from the bacterium M. smegmatis (MspA,B,C) can form pores in cell walls thus becoming a transport vehicle for the ruthenium-complexes. Once inside and irradiated, the ruthenium-complexes destroy the DNA and membranes of the cancer cell, and thus cause its death.
