[An in-vitro study of 99mTc sestamibi uptake by normal and neoplastic cell lines]

The hexakis (2-methoxy isobutyl isonitrile) technetium (I) (99mTc MIBI) is a representative molecule for a class of monocationic lipophile 99mTc compounds, knowing to be initially used like myocardial scintigraphic agents, and now also in oncological scintigraphy. This present study aims to compare the in vitro 99mTc MIBI cellular uptake on some normal and neoplastic cells. Three tumoral cell lines were used: M4Beu (pigmented melanoma), M3Dau (pigmented melanoma), MCF7 (breast cancer), in comparison with newborn rat cardiac myocytes and fibroblasts. Monolayers cultures cell were incubated for 1 hour with 37 kBq of 99mTc MIBI. Our results: (a) confirm a preferentially 99mTc MIBI uptake on the myocytes in comparison of the fibroblasts; (b) show that this uptake is very different on the neoplastic studied cultures cells, depending on the cell type (higher on M3Dau in comparison of the other two malignant cell lines, and also higher than the myocytes. The neoplastic cellular mechanisms to accumulate 99mTc MIBI, are only hypothetically understand; there are thought to be also in relation with the Nernst equations, applied at the plasmatic and mitochondrial membranes level, like in normal cells. A correlation with some phenotypic neoplastic cells characteristics, in relation with the malignancy tumoral potential seems possible. If there is the case, this can be a possible explanation of some in vivo imaging results, obtained with 99mTc MIBI, in oncologic scintigraphy.