Cienciaes.com: A more exact medicine against cancer.

2020-12-15 18:24:51

The same antitumor drug is relatively effective in treating many cases of lung cancer, but it is not effective in treating breast cancer. Now it has been discovered why.

Tumors occur due to the mutation of one or another gene involved in the control of cell reproduction. The genes whose mutations lead to this situation are called oncogenes. In many cases, these depend on the mutation of a single oncogene for their growth, which is why these tumors are said to be “addicted” to the oncogene.

The phenomenon of oncogenic addiction makes it possible to attack, through a drug, for example, the protein produced by the mutated oncogene, so that it stops working. If it is achieved, the tumor cells will stop their growth. However, once drug treatment against the oncogenic protein begins, some tumors are able to break their addiction and change the way they grow.

One of these tumors is the so-called triple negative breast cancer. This is the most aggressive type of breast cancer, precisely because it has lost three oncogenes to which it was initially addicted, yet has found a way to keep growing.

What is the way that triple negative breast cancer uses to keep growing? The answer to this question was not known. One potential suspect was the so-called epidermal growth factor receptor (REGF). This receptor is a protein in the cell membrane that under normal conditions is only activated when it detects that growth factor in the environment. However, when the receptor is mutated or produced in larger amounts than normal, it sends out its biochemical signal to stimulate cell reproduction even in the absence of growth factor. This makes it another oncogene.

There is a drug (called erlotinib) capable of blocking the activity of the REGF. This is effective in treating some types of lung cancers, which are addicted to REGF, but it is not effective in treating triple negative breast cancer. This seemed to indicate that the activation of REGF it was not the way triple negative breast cancer grew.

However, researchers from the University of Massachusetts, in the USA, in their studies, published in the journal Science Signaling, find that it is not true that triple-negative breast cancer is insensitive to the drug, but that the tumors defend themselves of its action by activating a molecular mechanism that prevents cell death by apoptosis in the presence of the drug. When it is excreted or broken down, cancer cells, which have only stopped growing but have not died, regain their reproductive capacity.

The discovery of this mechanism for slowing down oncogenic addiction in breast cancer now also makes it possible to block it by using another drug. With this mechanism blocked, cancer cells cannot pause their addiction to alcohol. REGF and the drug erlotinib is effective in killing them.
At the moment, these studies have only been carried out on cells in the laboratory. But there is hope that the research will lead to a cure for most of these types of tumors, so dangerous today.

Reference:
Cruz-Gordillo et al., Sci. Signal. 13, eabb9820 (2020) 17 November

Jorge Laborda 12-13-20

Works by Jorge Laborda.

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