Calcium-binding proteins in carcinoma, neuroblastoma and glioma cell lines

Advances in Intracellular Calcium Signaling Reveal Untapped Targets for Cancer Therapy

Intracellular Ca2+ distribution is a tightly regulated process. Numerous Ca2+ chelating, storage, and transport mechanisms are required to maintain normal cellular physiology. Ca2+-binding proteins, mainly calmodulin and calbindins, sequester free intracellular Ca2+ ions and apportion or transport them to signaling hubs needing the cations. Ca2+ channels, ATP-driven pumps, and exchangers assist the binding proteins in transferring the ions to and from appropriate cellular compartments. Some, such as the endoplasmic reticulum, mitochondria, and lysosomes, act as Ca2+ repositories. Cellular Ca2+ homeostasis is inefficient without the active contribution of these organelles. Moreover, certain key cellular processes also rely on inter-organellar Ca2+ signaling. This review attempts to encapsulate the structure, function, and regulation of major intracellular Ca2+ buffers, sensors, channels, and signaling molecules before highlighting how cancer cells manipulate them to survive and thrive. The spotlight is then shifted to the slow pace of translating such research findings into anticancer therapeutics. We use the PubMed database to highlight current clinical studies that target intracellular Ca2+ signaling. Drug repurposing and improving the delivery of small molecule therapeutics are further discussed as promising strategies for speeding therapeutic development in this area.

Expression of calbindin D-28K-like immunoreactivity in human SK-N-SH and SH-SY-5Y neuroblastoma cells

Calbindin D-28K is a calcium-binding protein first isolated from avian intestines, and more recently shown to be present in a number of other vertebrate species and in other tissues, including CNS neurones. Using immunocytochemical techniques and Western blotting, we have shown that a calbindin D-28K-like protein is expressed in two related human neuroblastoma cell lines, SK-N-SH and SH-SY-5Y. To our knowledge these are the first immortal neuronal cell lines shown to express calbindin D-28K.