Role of osteopontin in breast cancer patients

ABSTRACT Aim and background. In breast cancer, as in almost all neoplastic diseases, the prog -nosis is strictly related to the invasive capacity, local and distant, that characterizesthe growth of all tumors. Since the mechanisms that regulate replication of the neo -plastic cells, with consequent capacity to metastasize, are not completely known,identification of new markers represents the gold standard of research in the stratifi -cation of patients with such a pathology. Osteopontin, a specific phosphoglycopro -tein isolated from extracellular bone matrix and actively involved in mechanisms ofbone reabsorption, appears to play a key role in osteoclastogenesis at the level of theskeleton in some pathologic situations. It has been found that patients with metasta -tic bone lesions from breast or prostate cancer present, with respect to subjects with -out repetitive bone lesions, elevated serum levels of the protein, indicating that os -teopontin could play an important role in the development and progression of theneoplastic disease at the bone level.Methods and study design . The authors studied 26 patients with breast cancer, eval -uating as a marker also serum osteopontin levels.Resultsandconclusions. The results, although obtained on a small number of patients,showed that osteopontin evaluation in breast cancer patients can be a particularly in -teresting method of research in staging of the disease as well as in the prognosis, there -by attributing a role of a biotumoral marker also in the follow-up of the therapy.IntroductionBreast cancer is the main cause of death of women in the western world. However,owing to the possibility of an early diagnosis, in a high percentage of cases it is possi -ble to obtain good results in terms of cure and long-term survival. Unfortunately,when metastatic lesions are present, the prognosis is very poor. Extensive researchthroughout the last century has emphasized the prognostic significance of a numberof pathological factors, which include the size of the primary tumor, the histologicalgrade, and the appearance of tumor deposits in the draining lymph nodes of the pri -mary breast carcinoma. In spite of the progress observed in the study of tumorgrowth, one of the main limitations of modern oncology is the lack of knowledge onthe mechanisms that rule the kinetics of replication of neoplastic cells and particu -larly of its metastasizing capacity.Among the many studies carried out to identify the mechanisms underlying the ba -sis of tumor growth and secondary replication, interesting are those that havedemonstrated that osteopontin – a 44-kDa phosphotylated glycoprotein with theamino acid sequence Arg-Gly-Asp that elicits binding of integrin and is secreted bythe autocrine system of the cells of some aggressive multiple myeloma