One of the most exciting developments in cancer research is the increasing knowledge we have of the biological and biochemical processes involved in tumor development. Scientists are still years away from fully mapping the structural components of tumors, but they have successfully identified a number of proteins that are overexpressed in a variety of malignancies. CD200 is one such protein. Previous studies have shown CD200 expression as a prognostic factor in acute myeloid leukemia (AML) and multiple myeloma (MM) and now, researchers from France writing in the journal Biochemical and Biophysical Research Communications have published their findings on CD200 expression in a number of other cancers. They conclude that CD200 is a viable therapeutic target for cancer treatment.

Introduction to the Study

CD200 is a transmembrane protein whose expression has been shown to have immunosuppressive effects on the body. Some of these previously identified effects include inhibition of macrophages, which are important immune-system cells that digest pathogens and other foreign bodies, as well as induction of regulatory T-cells that suppress immune system activation and the inhibition of tumor-specific T-cell immunity. CD200’s tolerigenic effect, i.e., its ability to restrict an immune system’s response to a foreign body, has also been demonstrated in mouse models. In those cases, CD200’s immunosuppressive effects were a benefit to therapy, as they led to an increased survival rate after tissue transplant. CD200 has been implicated in a number of other pathologies and malignancies as well.

To look at CD200 expression in other forms of cancer, the authors examined a number of public sources, including the Oncomine Cancer Microarray database (http://www.oncomine.org), the Amazonia database (http://amazonia.montp.inserm.fr/) and the Integrated Tumor Transcriptome Array and Clinical Data Analysis database (http://bioinfo-out.curie.fr/ittaca/).

The researchers analyzed the data in two ways:

1. Expression of CD200 in malignant tissues from a variety of cancers; and
2. In cases were expression correlated with the cancer, they looked at the relationship between expression and tumor progression/stage.

Conclusion

Regarding the overall correlation of CD200 and cancer, they found significant overexpression of CD200 in the following areas: renal carcinomas compared to normal kidneys; head and neck carcinomas compared to normal head and neck tissues; testicular cancer compared with normal testicular tissue; pleural mesothelioma compared to normal pleural tissue; and colon carcinoma compared with normal colon tissue. The authors also found a high correlation between CD200 and advanced-stage disease, especially with bladder cancer, advanced-stage lung cancer and chronic myelogenous leukemia. They postulate that CD200’s immunosuppressive effects are responsible for this latter development, as the cancer can develop or remain in the body without triggering an immune system response. More research is certainly needed on this topic, but the authors definitely conclude that CD200 is overexpressed in a number of cancers and is often associated with a bad prognosis.

Labels: cancer, mesothelioma