Special Protein May Impact Mesothelioma Outcome


Mesothelioma patients whose cells express a protein called CD9 are likely to do better and live longer than those who don’t produce this special protein.

That news comes out of a laboratory at Hiroshima University in Japan. CD9 is a cell surface glycoprotein involved in cell growth, adhesion and mobility. Its expression is associated with several other types of cancer. To measure the impact CD9 expression has on mesothelioma cells, a research team at the Institute of Biomedical and Health Sciences in Hiroshima first measured what happened to mesothelioma cells in the lab when CD9 expression was knocked down through gene manipulation. In those cell samples, knockdown of CD9 resulted in more mobility for the cancer cells.

The team then examined CD9 expression in cell samples from 112 cases of malignant pleural mesothelioma. The cells came from patients with different histopathological subtypes. Among the 71 samples of the epithelioid subtype, CD9 expression was observed in 62. The team also found CD9 expression in 13 of the 20 samples of biphasic mesothelioma. The only exception appeared to be sarcomatoid mesothelioma, in which only 1 of 20 samples was shown to express CD9.

When CD9 expression was compared to survival, the results were clear: Mesothelioma patients whose cells expressed CD9 were more likely to survive for as long as two years than those whose samples showed no CD9. Sixty-three percent of all mesothelioma patients with CD9 were still living a year after diagnosis. A quarter of them were still living at 2 years. In contrast, mesothelioma patients without CD9 expression had a 39% one-year survival rate and only an 11% two-year survival rate.

And the CD9 patients had other factors in their favor, too. These patients tended to be younger than 60, have mesothelioma that was in an earlier stage, have the epithelioid subtype, and have undergone extrapleural pneumonectomy (for which patients must be in good overall condition) or chemotherapy. The study prompted the Japanese team to conclude, “CD9 expression is an independent favorable prognostic marker of malignant mesothelioma.”


Amatya, VJ et al, “CD9 expression as a favorable prognostic marker for patients with malignant mesothelioma”, January, 2012, Oncology Reports, pp. 21-28.

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