It is important to demonstrate the influence of the microenvironment in the process of metastasis

December 20, 2007

In the work defended at the University of the Basque Country (UPV/EHU), an in vitro culture model of human colon cancer was created in order to reproduce the gene regulation that is expressed in these cancer cells during their growth as metastasis in the liver of patients. This in vitro culture model provides a simple tool for the study and identification of the origin of the factors regulating this expression, as well as a simple form of the therapeutic evaluation for new pharmaceutical drugs that block this route.

Cancer of the colon is the third most common kind of cancer in our society. And, in many cases, the first symptoms usually appear when the disease is already in quite an advanced state. Of those colon cancer patients who suffer metastasis, approximately 45 % will develop hepatic metastasis.

It is this theme that the Gipuzkoan biologist, Ms Amaya del Villar, deals with in her PhD, recently defended at the Faculty of Medicine and Odontology at the University of the Basque Country (UPV/EHU). It is research work in which colon cancer -generated hepatic metastasis is analysed, a disease which may be propitiated by genes that are regulated by the very microenvironment or environment of the liver.

The PhD entitled "Study of the genes involved in hepatic metastasis of colon cancer and which are regulated by microenvironmental factors of the liver" was led by Fernando Vidal-Vanaclocha of the Department of Cell Biology and Histology at the UPV/EHU and obtained excellent cum laude. Cooperating in drawing up the doctoral thesis was the Pharmakine company and the Hepatic Surgery Unit at the Cruces Hospital in Bilbao.

Ms Amaya del Villar Álvarez is a graduate in Biological Sciences from the University of Navarra and currently works for the Pharmakine company, continuing her research into cancer and metastasis.

This study aimed, on the one hand, to create an in vitro culture model of human colon cancer that would enable reproducing the gene regulation expressed by colon cancer cells during their growth as metastasis in the liver of patients with hepatic metastasis. On the other, it was aimed at identifying the origin of the factors regulating the expression of those genes.

An in vitro model based on crops in the presence of conditional media

The in vitro model developed in this PhD thesis differs from current models in which the cell line from the human colon cancer is cultured in the presence of conditioned media of primary cells from the liver after being stimulated with tumour cell conditioned media. With in vitro conditioned media, the aim is to imitate the environment of the tumour cell during its implantation in an organ at a distance. This would be the simplest form to see the changes and responses produced with this kind of metastasis, and subsequently being able to develop new pharmaceutical drugs or therapeutic targets to combat it.

To this end, liver cells - hepatocytes and myofibroblasts - are isolated, and both cultured separately in the presence of conditioned media of a cell line of colon cancer. In each case, the media are collected in such a way that all the segregated soluble factors of these liver cells, responding to the tumour, are in the media. On the other hand, tumoural cells from the human colon cancer cell line were cultured for 24 hours in the presence of this conditioned media, in order to see the response that these produce in each case and compare it with both the hepatocytes and myofibroblasts.

More than 44,000 genes

To check the responses of the colon cancer tumoural cells in the conditioned media, a study of the genes was carried out and the origin of the factors regulating this expression identified. Once the 24 hours in the presence of conditioned media had passed, the nucleic acid of these cells was extracted and this subsequently subjected to the microarrays technique enabling the study of more than 44,000 genes at the same time. It was observed that one group of genes is regulated in the same way by both hepatocytes and myofibroblasts, but there are other groups that are regulated in a specific manner way by either hepatocytes or myofibroblasts. That is to say, genes regulated in the presence of conditioned media are different, depending on the cells. The biologist also observed that the hepatocytes regulate a significantly greater amount of genes than do the myofibroblasts.

"This study is only at its beginnings" stated the researcher. "Although we have possibly identified certain genes, further studies have to be undertaken. And, undoubtedly this is a field which will widen. The results so far obtained have to be corroborated with much wider studies, with a much larger number of patients, and so on", she added.

"But, basically, I think it important to demonstrate the influence of the microenvironment in the process of metastasis", she argued. "When studying cancer, it is good to have a more global, overall perspective, not solely focusing on the tumour or malignant cells".

"If we manage to find out the process of regulation in the tumour cell during metastasis, we will have achieved the possibility of developing therapeutic targets in order to try and avoid, as it were, the metastasis occurring".
-end-


Elhuyar Fundazioa

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