Introduction: When conducting a mammogram of the breast, great importance is attached to the detection of calcifications, which may indicate a malignant process.  The study of microcalcifications in breast tissue may have a great diagnostic value in the early stages, as recent studies have identified biominerals in the tissue of invasive ductal breast cancer (IDBC) that may influence on metastasis and prognosis in such patients.

Aim: To investigate the expression level of osteopontin (OPN) in the tissue of IDBC with the presence and absence of pathological biomineralization.

Materials and methods: For the study, 30 samples of breast cancer tissue (BCT) with biomineralization (group I) and 30 samples of BCT tissue without biomineralizates (group II) were taken. Histological and immunohistochemical (IHC) studies were used in the study. Anti-Osteopontin antibody was used in the IHC study. Positively stained cells were considered to have a complete stained cytoplasm and membrane. To evaluate the statistical analysis of the obtained results, we used Microsoft Excel 2010 with the application AtteStat 12.0 (determination of the average value of OPN expression and the significance of the difference (p)). Morphometric studies of micropreparations were performed using the software “SEO Scan ISH 285 AK-F IEE1394” (Ukraine). Quantitative assessment of IHC was performed by counting immunopositive cells in the field of view with a diameter of 1000mcm. Graphical representation of data was performed in the environment of Prizm 7.0.

Results: The average expression of OPN in BCT with biomineralization (91,745 ± 3,22) is higher than in tumor tissue of the control group (76,62 ± 3,26) with a significant difference between these indicators according to Student’s test (p˂0.01). The presence of pathological biomineralization leads to the high level of OPN protein expression in the tissue of IDBC. On the other hand, samples of IDBC without calcifications have significantly lower expression level of these proteins. It is well known that OPN is an acidic phosphoprotein, which is expressed in mineralized tissues and it inhibits hydroxyapatite formation by binding to the surface of the crystals.

Conclusions: OPN overexpression may be regarded as a protective tissue response to the development of ectopic calcification.