Less Toxic Chemotherapy Drugs Developed

Researchers from NYU have developed and studied the biological activity of five new hybrid metal–organic, knotted molecules, termed metal–organic trefoil knots (M-TKs). These molecules can effectively deliver metals to cancer cells, demonstrating the potential to act as a new category of anti-cancer agents. In the study, published in Chemical Science, the researchers report that these nanoscale, water-soluble M-TKs showed high potency in vitro against six cancer cell lines and in vivo in zebrafish embryos.

The M-TKs were generated by metal-templated self-assembly of a simple pair of chelating ligands. They were well tolerated in vitro by non-cancer cells while also being significantly more potent than cisplatin—a common chemotherapy medication—in both human cancer cells and zebrafish embryos. In cultured cells, M-TKs introduce reactive oxygen species (ROS) that damage the mitochondria of cancer cells but not the nuclear DNA or the plasma membrane.

“The cytotoxicity and wide scope for structural variation of M-TKs indicate the potential of synthetic metal–organic knots as a new field of chemical space for pharmaceutical design and development,” says senior author Ali Trabolsi. “There is significant promise for developing new cancer therapies that can complement the existing chemotherapy options that are currently used to treat nearly half of all cancer patients undergoing chemotherapy.”

The M-TKs synthesized by the research team were found, in many cases, to have greater potency than has been previously reported in cisplatin and other metal complexes, explains first author Farah Benyettou. The main delivery routes were macropinocytosis and both caveolin- and clathrin-mediated endocytosis, which are all more active in cancer cells than in normal cells. Cisplatin and other small molecules penetrate cells by diffusion, which is less cancer-selective in vitro. The researchers hypothesize that the molecules they have developed are less toxic to healthy cells because they are internalized less.

These findings confirm the viability of studying the effects of these compounds in whole vertebrates, as the M-TKs were well tolerated by zebrafish and appeared to selectively attack dividing cells. In the next stage of developing M-TKs, research efforts will focus on the mechanism of action of the M-TKs to determine whether their ROS-mediated toxicity involves specific intracellular targets.

Image: An illustration of how these knotted metal-organic molecules are internalized by a cancer cell, triggering a biological activity that the cancer cell cannot handle and resist, causing the cancer cell to die. Image courtesy of Jumaanah Alhashemi.