The multidirectional role of osteopontin in cancer

Osteopontin (OPN) was described for the first time as a potential marker of neoplastic transformation by Senger et al. in 1979.Studies suggesting an important role of OPN in oncology, allergology, nephrology and cardiology have been published for many years.However, the largest number of articles pertains to the role of OPN in neoplastic transformation and will surely facilitate future determination of OPN levels in blood or cancer tissues with the purpose of disease diagnosing, staging, prognosing metastases and monitoring the treatment effectiveness.Numerous studies showed that high OPN expression levels accompany metastases formation; the protein was also confirmed to be involved in stimulation of cell proliferation and formation of new blood vessels, i.e. angiogenesis.OPN was also shown to be capable of binding the CD-44 receptors, which facilitates migration and invasion of cancer cells into the blood vessels.Correlation was also demonstrated between OPN expression and the time to disease recurrence and overall survival in patients with breast cancer, gastric cancer, hepatocellular cancer, hormone-dependent prostate cancer, kidney cancer and endometrial cancer.The exact mechanism responsible for OPN's role in neoplastic transformation remains unclear and numerous research studies are conducted in this area.