Transcript

NARRATOR: DNA is the complex molecule inside all living cells, shown here in a very simplified form. Like all cells, cancer cells grow by reproducing the DNA. And the assumption had to be that, somehow, cisplatin’s anticancer properties had to do with its interference in this process.

STEPHEN LIPPARD: Every time the cell divides it has to reproduce its DNA, completely and accurately. And, in order for it to function, it has to take the message that is encoded in the DNA, transcribe it into RNA and ultimately translate that into proteins. We know that platinum blocks both of these processes – replication and transcription.

NARRATOR: The vital portions of DNA are the centre groups. These are known as bases and they hold together the two strands of the double helix. The bases are adenine, thymine, cytosine and guanine. This is the chemical formula for guanine. What is important here is the nitrogen labelled as N7. It’s important because NMR was able to show that cisplatin could bond to the nitrogen at this site on the guanine base. This early work showed that most of the cisplatin formed what is called an adduct by linking to two neighbouring guanine bases on the same strand of the DNA through the N7 atom. We call this an intrastrand adduct because the bonding is all on the same strand.