How a cancer drug carrier's structure can help selectively target cancer cells

The main culprit in cancer is healthy cells that have gone rogue and acquire the ability to divide uncontrollably. These cells acquire growth advantages over normal cells and manipulate their environment by altering the cellular pathways involved in growth and metabolism. Over the past few decades, various altered pathways and proteins have been identified as targets for therapeutic interventions. However, what remains challenging is selectively targeting cancer cells and ensuring that the drug reaches the tumor in adequate amounts, without severely affecting normal cells. And in this regard, biocompatible delivery vehicles (which are non-toxic to normal cells) can be useful.

One such potential candidate is "porphyrins," a group of organic cyclic compounds that form the functional center of several proteins in the human body. Porphyrins are known for their "photosensitizing" effects, that is, their ability to release reactive oxygen species upon light stimulation. These reactive species are what gives porphyrins their anticancer activity. Porphyrins have another advantage: structurally, they are composed of four subunits called "pyrrole subunits," which give them specific electronic properties. These electronic properties, in combination with receptors on cancer cells, facilitate the selective accumulation of porphyrins in cancer cells, thereby serving as an effective drug delivery system. But how the steric position (atomic arrangement) of the functional groups bound to porphyrins favors maximum accumulation and distribution of porphyrin-conjugated drugs in cancer cells hasn't been well studied.

To answer this question, researchers at Tokyo University of Science, including Asst. Prof. Toshifumi Tojo, Mr. Koshi Nishida, Assoc. Prof. Takeshi Kondo, and Prof. Makoto Yuasa, dug deeper into how the structure of porphyrin derivatives can affect tumor accumulation. Their findings are published in the journal END