Cell Proteins May Predict Mesothelioma Prognosis

A cell protein devoted to regulating water transport and another related to DNA replication could be important keys to improved mesothelioma prognosis.

The American Cancer Society has released the results of a study on the relationship between a protein known as Aquaporin 1 (AQP1), which regulates water movement through the cell membrane, and treatment effectiveness for patients with mesothelioma.  At the same time, an international research team has also found a correlation between mesothelioma prognosis and the expression of the protein TIF-2.

Both of these new studies represent a relatively new approach to the treatment of mesothelioma, one focused on manipulating the complex inner workings of cells.  The Australian research teams that conducted the multi-center AQP1 study examined the AQP1 levels in two groups of mesothelioma patients – 80 patients who had undergone radical mesothelioma surgery (extrapleural pneumonectomy) and 56 patients who underwent more conservative treatments.

For both groups of patients, expression of AQP1 in 50% or more of cells in the tissue sample was associated with “significantly enhanced survival.”  Among mesothelioma patients who had undergone EPP, those in the higher AQP1 category survived 30.4 months compared with 9.4 months in the lower AQP1 group.  Among the more conservatively-treated mesothelioma patients, higher AQP1 levels resulted in survival rates that were three times higher than those with lower AQP1 – 15 months as opposed to 5 months. The survival results appeared to be independent of any other traditional mesothelioma prognostic factors, including histologic subtype, pathologic stage, sex, and age at diagnosis.

The results prompted the research team to recommend that “immunohistochemical labeling for AQP1 should be included in the routine histopathologic workup” for all mesothelioma patients. They further predict that chemicals which can either promote or block the cellular expression of AQP1 “may become useful for treatment.”

In a separate international study, researchers looking at TIF-2, a protein found in the cell nucleus that is associated with DNA replication, say they are the first to confirm a correlation between TIF-2 expression and improved mesothelioma prognosis.  In the 89 mesothelioma tumor biopsies studied, those with low TIF-2 expression survived a median of 9 months, while the median survival for those with higher TIF-2 expression was 20 months. Because mesothelioma is a fast-growing cancer, the ability to predict prognosis can be especially crucial, allowing doctors to tailor treatments for better results.

Sources:

Kao, SC et al, “Aquaporin 1 is an independent prognostic factor in pleural malignant mesothelioma”, October 21, 2011, Cancer, Epub head of print.
Jennings, CJ, “Sustained Expression of Steroid Receptor Coactivator SRC-2/TIF-2 is Associated with Better Prognosis in Malignant Pleural Mesothelioma”, October 18, 2011, Journal of Thoracic Oncology, Epub ahead of print.