Curing Cancer with Salt?

Cancer is a highly emotive subject and horribly prevalent disease, so miracle cures are often the subject of considerable media coverage. The Daily Mail in particular is well-known for articles detailing the latest “cure”, or indeed reporting the newest cancer causing scare, with eagled-eyed bloggers cataloguing lists of cures and carcinogens (note the number of substances that the Mail believes both cause and prevent cancer). So with the latest headline “Salt injection ‘kills cancer cells’” published by the Daily Mail and others, is it really that simple?

The Science

The reports describe a paper from the research groups of Prof Philip Gale (University of Southampton) and Prof Jonathan Sessler (University of Texas at Austin) published in Nature Chemistry. The study aimed to induce apoptosis – automated cell death – by artificially changing the concentration of ions inside cells. The transport of ions, such as sodium, potassium and chloride, in and out of cells is regulated by ion channels, which act like gates giving access across cell membranes. Apoptosis is known to occur when intracellular ion levels become imbalanced, but cancerous cells resist this death by rendering ion channels inactive, so an artificial method to transfer ions across a cell membrane could be fatal for cancer cells.

Ion transport is tricky, as ions are small, charged and hydrophilic – salt readily dissolves in water – whereas the interiors of cell membranes are lipophilic (or fatty), so trying to force ions across a membrane is like trying to mix water and oil. Try dissolving salt crystals in some olive oil at home; it just won’t happen! Sessler and Gale report a type of molecule known as an ion transporter, which binds to a pair of sodium and chloride ions and presents a lipophilic exterior, effectively smuggling the precious ionic cargo into the cell. The result of this “salt injection” is indeed apoptosis in cultured human (lung, colon, pancreatic and prostrate) cancerous cells as a result of increased intracellular chloride levels.

The Reporting

The perceived simplicity of the potential treatment forms the basis of most media reporting, with “salt injections” being touted as a headline cure. This is obviously inaccurate, as it is the synthetic ion transporter doing the hard work here. The articles themselves are based mostly around a press release, but actually do a good job of discussing the research in an appropriate context, with quotes from the authors and a reminder to the readers of the caveat that the transporters currently do not distinguish between healthy and cancerous cells, a major drawback of many treatments. We’ve said it before – read the whole article, not just the headline – but judging by the comments on the Daily Mail website many readers have sadly come away with the opinion that salt is a wonder cancer cure.

The Future?

As with most media stories covering new cancer treatments, there is still a long way to go with this methodology, not least regarding selectivity of the ion transporter. Moving from isolated cells to actual organisms is also a big step, but this report is certainly a step in the right direction, and will no doubt lead to many further studies. Prof Sessler certainly needs no extra motivation, having fought off leukemia twice, both as an undergraduate and postgraduate student. Additionally, cystic fibrosis is caused by problems with sodium and chloride ion balancing, giving scope for further medicinal applications of synthetic ion transporters.

S.-K. Ko, S. K. Kim, A. Share, V. M. Lynch, J. Park, W. Namkung, W. V. Rossom, N. Busschaert, P. A. Gale, J. L. Sessler & I. Shin (2014). Synthetic ion transporters can induce apoptosis by facilitating chloride anion transport into cells. Nature Chemistry, advanced online article. DOI: 10.1038/nchem.2021