Prostate-specific membrane antigen (PSMA) (also known as glutamate carboxypeptidase II) is a type II transmembrane glycoprotein that has become an increasingly prominent imaging biomarker 1. PSMA has emerged as a useful target in PET imaging of prostate cancer, especially in the evaluation of small volume lymph node and bone metastases 2.
Its structure consists of 750 amino acids (100-120 kDa), with a 19-amino acid intracellular segment, a 24-amino acid intramembrane component and a 707-amino acid extracellular domain 1. PSMA is encoded by a gene (FOLH1) located on the short arm of chromosome 11 7.
- significantly over-expressed in prostate cancer tissue 2
- expression is positively correlated with tumour grade, pathological stage and degree of disease recurrence 2
- PSMA is internalised upon binding, resulting in enhanced tumour uptake and retention 3
- ideal target for small-molecule radiopharmaceuticals 3
- 1. Israeli, R. S., Powell, C. T., Fair, W. R., & Heston, W. D. (1993). Molecular cloning of a complementary DNA encoding a prostate-specific membrane antigen. Cancer Res, 53(2), 227-230.
- 2. Hofman, M. S., & Iravani, A. (2017). Gallium-68 Prostate-Specific Membrane Antigen PET Imaging. PET Clin, 12(2), 219-234. doi:10.1016/j.cpet.2016.12.004
- 3. Eder, M., Eisenhut, M., Babich, J., & Haberkorn, U. PSMA as a target for radiolabelled small molecules. European Journal of Nuclear Medicine & Molecular Imaging, 40(6), 819-823.
- 4. Silver, D. A., Pellicer, I., Fair, W. R., Heston, W. D., & Cordon-Cardo, C. (1997). Prostate-specific membrane antigen expression in normal and malignant human tissues. Clin Cancer Res, 3(1), 81-85.
- 5. Chang, S. S., Reuter, V. E., Heston, W. D., Bander, N. H., Grauer, L. S., & Gaudin, P. B. (1999). Five different anti-prostate-specific membrane antigen (PSMA) antibodies confirm PSMA expression in tumor-associated neovasculature. Cancer Res, 59(13), 3192-3198.
- 6. Haffner, M. C., Kronberger, I. E., Ross, J. S., Sheehan, C. E., Zitt, M., Muhlmann, G., . . . Bander, N. H. (2009). Prostate-specific membrane antigen expression in the neovasculature of gastric and colorectal cancers. Hum Pathol, 40(12), 1754-1761. doi:10.1016/j.humpath.2009.06.003
- 7. Leek J, Lench N, Maraj B, Bailey A, Carr IM, Andersen S, et al. Prostate-specific membrane antigen: evidence for the existence of a second related human gene. British Journal Of Cancer. 1995;72:583.