Tag Archives: adaptor proteins

Adaptor protein Ruk/CIN85 modulates resistance to doxorubicin of murine 4T1 breast cancer cells

I. R. Horak, D. S. Gerashchenko, L. B. Drobot

Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
e-mail: iryna.horak@gmail.com

The acquisition of chemoresistance in the course of tumor progression includes activation of membrane ABC transporters, detoxification enzymes, cell cycle deceleration and activation of specific signaling pathways such as Akt/mTOR, MAPK, NF-κB. Adaptor proteins play an essential role in the assembly of supramolecular signaling complexes, maintaining and directing the intracellular signaling. One of such proteins, called Ruk/CIN85, is strongly associated with malignant transformation and metastasis. In present study we investigated the Ruk/CIN85 effect of up/down-regulation on the transforming potential and doxorubicin resistance of highly aggressive mouse breast adenocarcinoma 4T1 cells. It was demonstrated that 4T1 cells overexpressing Ruk/CIN85 possessed increased resistance to doxorubicin (in the range of concentrations 0.1–10.0 µM) while knockdown cells were the most sensitive. Also, high levels of Ruk/CIN85 in 4T1 cells positively correlated with their ability to form colonies in semi-solid agar. Ruk/CIN85-overexpressing cells formed four times more colonies in comparison with Ruk/CIN85 nockdown cells, the growth of which revealed higher resistance to doxorubicin action.

Multiple molecular forms of adaptor protein Ruk/CIN85 specifically associate with different subcellular compartments in human breast adenocarcinoma MCF-7 cells

B. O. Vynnytska-Myronovska1, Ya. P. Bobak1, G. V. Pasichnyk2,
N. I. Igumentseva1, A. A. Samoylenko2, L. B. Drobot2

1Institute of Cell Biology, National Academy of Sciences of Ukraine, Lviv;
2Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
e-mail: drobot@biochem.kiev.ua

Ruk/CIN85 is a receptor-proximal ‘signalling’ adaptor that possesses three SH3 domains, Pro- and Ser-rich regions and C-terminal coiled-coil domain. It employs distinct domains and motifs to act as a transducer platform in intracellular signalling. Based on cDNA analysis, various isoforms of Ruk/CIN85 with different combination of protein-protein interaction domains as well as additional Ruk/CIN85 forms that are the products of post-translational modifications have been demonstrated. Nevertheless, there is no precise information regarding both the subcellular distribution and the role of Ruk/CIN85 multiple molecular forms in cellular responses. Using MCF-7 human breast adenocarcinoma cells and cell fractionation technique, specific association of Ruk/CIN85 molecular forms with different subcellular compartments was demonstrated. Induction of apoptosis of MCF-7 cells by doxorubicin treatment or by serum deprivation resulted in the system changes of Ruk/CIN85 molecular forms intracellular localization as well as their ratio. The data obtained provide a new insight into potential physiological significance of Ruk/CIN85 molecular forms in the regulation of various cellular functions.