New hope for asbestos victims

Malignant tumours caused by asbestos contamination are amongst the most aggressive types of cancer known and in most cases prove to be fatal. The latest results from studies of the protein calretinin by the research team led by Prof. Schwaller of the Department of Medicine at the University of Fribourg show promising approaches to the treatment of such malignant mesotheliomas.

Asbestos is banned in Switzerland and in the EU, but still exists in many older buildings. (Image: Thinkstock)

Diseases such as asbestosis (one of the lung diseases caused by the inhalation of dust), lung cancer or malignant tumours of the pleura or, more rarely, the peritoneum, so-called mesotheliomas, can be caused by asbestos dust. For this reason the use of asbestos has been banned in Switzerland for more than 20 years, but in spite of this, this dangerous material still exists in many older buildings. In countries like Canada, China or Russia, asbestos is still being mined and processed. The delay between being exposed to asbestos dust and the appearance of a malignant mesothelioma is quite long – 20 to 40 years – however the time a patient still has to live after diagnosis is in most cases less than a year. As yet there is no effective treatment. This is what makes this recent discovery by Professor Beat Schwaller’s research team in the Department of Medicine at the University of Fribourg so interesting.

Enemy identified

Prof. Schwaller und his Team have been researching the protein calretinin and its possible role in cells deriving from malignant mesotheliomas for about twenty years. It is known that calretinin, a so-called calcium binding protein, is overexpressed in mesotheliomas. But its exact function, in healthy cells as well as in cancerous cells, is still largely unknown. As early as 1993, calretinin antibodies were produced by Prof. Schwaller in his laboratory and were used as positive markers in the identification of mesotheliomas. These antibodies are still being used today by pathologists all over the world in the diagnosis of mesotheliomas. By applying methods used in molecular biology it has now become possible to efficiently retard the expression of calretinin in mesothelioma cells – with the surprising result that the cancerous cells die off. This is caused either by what is called apoptosis, the physiological degradation of the cell, also called programmed cell death, or by necrosis, pathological cell death.

From this the researchers were able to conclude that there is no calretinin in normal, healthy mesothelial cells, but that it does occur in malignant pleural mesotheliomas. His team was also able to show that a large proportion of malignant tumour cells die off when the calretinin in them is reduced. This new knowledge gained through basic research has enabled the calretinin protein to be identified as a new and potentially promising target in the treatment of cancer. This discovery is all the more interesting because current treatments for malignant mesotheliomas are extremely limited and new treatments are urgently required.

This research was primarily carried out by Diplomassistent Walter Blum under the direction of Prof. Schwaller and was recently published in the renowned „International Journal of Cancer“.

Link to the publication:

Walter Blum, Beat Schwaller (2013). Calretinin is essential for mesothelioma cell growth/survival in vitro: A potential new target for malignant mesothelioma therapy? International Journal of Cancer. (doi: 10.1002/ijc.28218)

Walter Blum, Diplomassistent, Department of Medicine, University of Fribourg, 0041 26 300 84 95, walter.blum@unifr.ch