Unravelling sorcin mechanism of action in multi drug resistance tumor cells

Sorcin is a calcium binding protein, mainly known for its role in muscle contraction, where it participates in the termination of the contraction and in the onset of relaxation by modulating calcium channels at the endo/sarcoplamic reticulum (Ryanodine Receptor and SERCA pump) and at the plasma membrane (Na+/Ca2+ exchanger). Since few years ago, sorcin has started to be reported as overexpressed in several different multi drug resistant tumors but little was known about its network of interaction and its behavior in the cell in different stages of the cell cycle. Sorcin overexpression and silencing alter cell morphology and cell fate and protein modifications (mainly phosphorylations) affect sorcin functions. Moreover sorcin binds directly chemotherapics (doxorubicin in particular) giving a partial explanation for the manifestation of Multi Drug Resistance in tumor cells. Sorcin is also abundant in the brain and the neuroblastoma cell line Sh-Sy5y treated with compounds mimicking stimuli that induce neurodegenative manifestations shows even an increased level of expression of sorcin raising the hypothesis that sorcin might be involved in mechanisms linked to neurodegenerative disorders.