Food with palm oil promotes more aggressive metastases

BarcelonaPalmitic acid, one of the usual suspects in unhealthy diets, has just received a new witness that further undermines its presumption of innocence. If for some years it has been accused of being responsible for increasing cholesterol levels or having a negative impact on the onset of heart disease, now it is time to assess its role in cancer. And as it was suspected four years ago, it has been found that this acid, one of the major components of palm oil, triggers a mechanism that promotes the activity of metastatic cells and, therefore, the risk of generating distant tumors. In the same way, it induces a memory effect that makes its behaviour more aggressive. The research, led by ICREA researcher Salvador Aznar-Benitah, at the Institute for Research in Biomedicine (IRB) in Barcelona, was published last Wednesday in the journal Nature.

The results of the research reveal that this phenomenon, which could be universal for all types of solid tumours, occurs in greater proportion when we consume a diet rich in palmitic acid, a saturated fatty acid of vegetable origin present in many processed foods, in addition to meat and dairy products, which makes it almost inevitable for practical purposes. "When a tumour is exposed to palmitic acid, mechanisms are activated that cause the cells that are released to have a more aggressive metastatic potential", the researcher explains. In addition, this exposure, which comes from the diet, generates in certain tumour cells the capacity to store this mechanism in their memory. "The tumour has a memory of palmitic acid, so that future exposures will trigger the metastatic process again", he adds.

In the research, focused on oral cancers and melanomas, it has been detected that this phenomenon only occurs in a small population of tumour cells. "Tumours are heterogeneous by definition, which means that many cell types coexist", says Aznar-Benitah. In this case, these are cells with positive CD36 protein expression. "We have identified them in the periphery of the tumour, and together they represent only 1% to 5% of the total". As it has been known for years, cancer cells are shed from a tumour every day. While a large majority of them are non-viable or are destroyed by the immune system, a very small part infiltrates the blood system and reaches a distant point where it will eventually take root and generate a new tumour. Logically, the first to fall off are those in the periphery. And if they are CD36 positive, they will incorporate the toolbox they need to produce metastasis.

The Aznar-Benitah team's line of research gave its first major results in 2017, when it corroborated that palmitic acid could indeed have carcinogenic effects. The new results detail the mechanism. In addition, the comparison with different types of tumours, such as breast, kidney, lung and pancreas, among others, from publicly available databases available to scientists, "suggests" that they also contain populations of CD36-positive cells that eventually lead to aggressive metastasis. The research also shows that blocking this protein reduces the risk of metastasis to almost zero. This characteristic has been translated into several patents and the launch of a biotechnology company for the development of drugs based on the inhibition of the CD36 protein. The company has raised 30 million euros in investment between 2019 and 2020.